Dette data, athe Pivaiant Arie Aiea tesln'® a — — a a On ebt thy eethnty0 fo Mcedes heh ny Dehn anRy a ba Pperdhi outer eteAa sta dale teed =e af n Src " é i vba ag EP Mihm ttemitre rs Aholinian ten Ant Ppa pre errata pay eepearer dear ree pike: Bec rasa a Tey TER DT AD a at S act. te Ray adap TO Re Re ors Teo: nha GP. Vania fhe ne ae et A Nth aa Nem DM ag oe ably heal Fate Doig Bente well Mny NM EK mci aleeee Sosa mash ‘ Ba age Sting 0 Atay nthe Shah Parente paca La Daten Reelin Matty icnn hye Bathe 7 nee Wm ee ea Tas ome Tae pit w? Reem eaAien Dates e ns V\4 NH ay \ \ THE N arr GHOLOGICAL MAGAZINE: oR, Monthly Journal of Geology: WITH WHICH IS INCORPORATED Try Gb OL OG lS r. NOS. CCXCY. TO CCCVI. EDITED BY HENRY WOODWARD, LL.D., F.B.S., F.GS., F.Z.S., FRMS., OF THE BRITISH MUSEUM OF NATURAL HISTORY ; VICE-PRESIDENT OF THE PALHONTOGRAPHICAL SOCIETY, MEMBER OF THE LYCEUM OF NATURAL HISTORY, NEW YORK; AND OF THE AMERICAN PHILOSOPHICAL SOCIETY, PHILADELPHIA; HONORARY MEMBER OF THE YORKSHIRE PHILOSOPHICAL SOCIETY; OF THE GEOLOGISTS’ ASSOCIATION, LONDON; OF THE GEOLOGICAL SOCIETIES OF EDINBURGH, GLASGOW, HALIFAX, LIVERPOOL, AND NOR- WICH; CORRESPONDING MEMBER OF THE GEOLOGICAL SOCIETY OF BELGIUM; OF THE IMPERIAL SOCIETY OF NATURAL HISTORY OF MOSCOW; OF THE NATURAL HISTORY SOCIETY OF MONTREAL; AND OF THE MALACOLOGICAL SOCIETY OF BELGIUM. ASSISTED BY ROBERT ETHERIDGE, F.R.S. L. & H., F.GS., F.C.S., &., OF THE BRITISH MUSEUM OF NATURAL HISTORY. WILFRID H. HUDLESTON, M.A., F.RB.S., Sec.G.S. AND GEORGE J. HINDE, Px.D., F.G.S., &c. NEW SERIES. DECADE IIt. VOL. VI. JANUARY—DECEMBER, 1889. ad ff LONDON: TRUBNER & Co., 57 ann 59, LUDGATE HILL. F. SAVY, 77, BOULEVART ST.-GERMAIN, PARIS. 1889. fh tome 7 (oe ec avai \j No a : THE ‘EOLOGICAL MAGAZINE. a , NEW SERIES. : DECADE III. VOL. VI. — a JANUARY—DECEMBER 1889. hit ro ‘ 1 ; os ~ . 5 i = : Ve 5 ¢ 0 ‘ : ; { ‘ - =; ' ys LIST OF WOODCUTS. Diagram of Section of Bethesda Quarry . . - - + + «+ «@ pacontocted’ Slate: Rocksis <6. aise ie + = ems es Protaster brisingordes, Gregory » « + + «+ + « © = Decuonpontne: MarthysiCrust, kets he < s <\< oly Reet (sel a Diagram to illustrate Mr. Harker’s paper . . . . « Section across the Valley of the Darent . 5 iPhysical’@hanges inthe Harth’s;€rust- "2 .- 5 «ays Cervical vertebra of Calamospondylus Foxi ». « « »« «© «+ Ascoceras Murchisont, Barr. » ». .« « « « -@ Map of the Geology of the Lake District Physical Changes in the Harth’s rust . . ». . . = = Secular Straining of the Earth . . . Cinseiping: Ci Siolleeaho) lay dae, Gg OO 8 ee 6 8 ge ne =i PP, . By Gh seins 0. oka o: 6 >, cole Cap lone f@EUlen a, G6 Ko Vax. GCS Vy ee 5) a) st i ie ee Diagram-section of Rocks at Rifle Range, near Ottawa nas Turrilepas Canadensis, H. Woodward Vertebra of Arctosaurus Osborni, Adams . 6. io) 6 Ichthyosaurus Paddle showing the Contour of the Integuments khinobatus Bugesiacus, Thiolliere? sp. Ceres hg.) -oolto.l) (opis Sections at right-angles to the cleavage-planes. ‘‘ Eyes” of Pyrites in Slate Outline of calices of Phillipsastrea radiata and P. tuberosa ° SW OG Jz ong, hls 6 6 6 6 6 56 0 6 5 6 0 Transverse section of Roemerta minor, Schliiter Vertical section of Roemeria minor, Schliiter Transverse section of Caliapora Battersbyi, E. & H. Transverse section of Caliapora Labechei, E. & H. Dinotherium giganteum, Kaup 6: occ cinmmmoie roa 6. 0 Mlewaitie Unggrasizisys IKI). 6 0 Llephas planifrons, Fale. & Cautl. 6, NOMNRRORERC TIO Ob 0. iG: vob Llephas primigenius, Blum. . . « « Sh ta Shcalen oC uM Mattox Tate Forms of Skulls and Skeleton of Depa ia Penge ens O06) OHO Zonal Structure in Olivine sepa let Nel See! “c) lien ol, oO OMAR R Toute tie Celonautilus cariniferus shee eye: wy ute) tah Fok MteMMe et ea Nautilus pompilius Pap At OnE .01 Os Om LircieO Ol oom mola Tooth of Carcharodon megalodon » »« »« +» «© « « «© « « Organic Remains and Mineral Bodies from Deep-sea Deposits . . .- Section of a Volcanic Cone 5 1\6 SectionotMeavas, “luttsseumicessetea ie: lc) 2 E * A . ° « one 5) l ‘ eat a y ‘* Ye | fi i I : ~ tr 7 hl ; : , : : y 7 ‘ " y | OES i 7 G 1 7 vs A ~ i j cep 4 » is 4 : : { 4 bn x ite att “he Bs fs —- Geol. Mag 1889. Decade lI. Vol VI.PLI.~ % .e8 QW ee i 3 2 RE Traquair del. E..C. Woodward lth, Wi West Newman &Coamp, | }lomosteus. 2,3 Coceosteus ‘THE GEOLOGICAL MAGAZINE. NEW SERIES. | DECADE I) VOL. VI. No. I—JANUARY, 1889. Oil E GEE NPA Nh A Fel BCE Ss —— I.—Howuosrzvs, ASMUSS, COMPARED witH CoccosTzus, AGASSIZ. By Dr. R. H. Traquair, F.R.S., F.G.S. (PLATE I.) HE creature which forms the subject of the present communica- tion is the same as that which was described as Asterolepis by Hugh Miller in his “‘ Footprints of the Creator,” and consequently its remains are at present better known to British geologists and paleontologists under that name. Why, then, alter a name which we have used so long ? is a question likely to be asked by those who have not critically studied the complicated mesh in which the Synonymy of the name “ Asterolepis”’ is entangled. The genus Asterolepis was proposed by Hichwald in 1840! for fragmentary remains of the exoskeleton of a vertebrate organism, from the Russian Devonian rocks, allied to Pterichthys, Ag. To these remains Agassiz also applied the name Chelonichthys, which he subsequently withdrew in favour of As/erolepis as having priority ; and with them he also identified generically certain large bones and plates from the Lower Old Red of Dorpat, some of which were first figured by Kutorga® as “Trionyx” and “ Ichthyosauroides,” and of which a considerable number, collected by Asmuss, were reproduced in plaster and copies sent to Agassiz. A number of these casts were figured by Agassiz,° as of bones of “ Asterolepis,” some of which are generically identical with the creature of whose bones and cranial buckler many fine specimens from Thurso, largely collected by Robert Dick, came into the possession of Hugh Miller. And thus it was that these remains came to be figured by Hugh Miller as belonging to Asterolepis, although they had no affinity to the creature to which Hichwald originally gave that name, their identi- fication with which being entirely due to a mistake of Agassiz, misled as he was by their mere external sculpture, consisting of small tubercles with stellate bases. For, that “ Asterolepis” cannot be applied to any of the remains from Dorpat represented by these casts, is unconsciously shown by * Die Thier- und Pflanzenreste den alter rothen Sandsteins und Bergkalks in Nowgorodschen Gouvernement,” Bull. Acad. Imp. St. Pétersburg, tome vii. p. 78. Beitrage zur Geognosie und Palaeontologie Dorpats, 1835-37. 3 Poiss. Foss. du vieux Grés rouge, tab, xxxii. DECADE III.—VOL. VI.—NO. I. 1 2 Dr. Rk. H. Traquair—Homosteus and Coccosteus compared. Agassiz himself, isasmuch as he figured as ‘“‘ Asterolepis ornata,” Hich- wald, a nuchal or median occipital plate of unmistakeable Pterich- thyan character,’ apparently quite unaware of the significance of its shape. Nevertheless Agassiz in some controversial remarks on the subject insisted that his Chelonichthys (= Asterolepis) had nothing to do with Pterichthys !? Now, in 1856, Asmuss published a thesis* in which he minutely described the Dorpat fossil bones, including the subjects of the aforesaid casts, and made out of them two genera, Homosteus and Heterosteus, with many species. In the former of these two, namely Homosteus, Hugh Miller’s fish, the so-called “ Asterolepis of Strom- ness,” is clearly to be recognized. Upon these facts Pander insists in his ‘“ Placodermen,” and not only did he propose to replace “‘ Asterolepis” by Homosteus in the case of Hugh Miller’s fish, but believing Asterolepis, Wichw., to be altogether identical with Pterichthys, Agassiz, as the name is un- doubtedly prior, he proceeded to cancel the latter name altogether. Naturally Pander’s views excited opposition in this country, where the names brought into use by Agassiz and Hugh Miller had become classic through the writings of these distinguished men. Sir Philip Egerton, who does not seem to me to have thoroughly understood the situation, fiercely combated the proposals of Pander in the following words: “ Having read both sides of the question with great care, my own impression is that Prof. Hichwald may perhaps have included in his genus Asterolepis some fragments which he subsequently ascertained (through the more perfect Scotch specimens sent to Russia by Dr. Hamel) to belong to the genus Pierichthys of Agassiz, and hence discarding the majority, namely, Asterolepis proper, assigns this name to the minority, to the ex- clusion of the Agassizian name. In the mean time Prof. Agassiz, then engaged upon his ‘ Poissons Fossiles du vieux Grés Rouge,’ received through Prof. Brown, from Eichwald himself, specimens of his Asterelepis, which had no reference to Pterichthys, but were identical with the genus Chelonichthys established upon specimens brought over from Russia by Sir Roderick Murchison, and of which other specimens were found in the Orkney beds. On making this discovery he at once relinquished his own name, Chelonichthys, and adopted Asterolepis of Hichwald. If now it is sought to supersede Pterichthys of Agassiz by Asterolepis of Kichwald, it is surely just that the term Chelonichthys should be retained for Hichwald’s reject- amenta, rather than Homosteus of Asmuss, a name of much later date than that of Agassiz.” 4 But whatever the specimens from the Orkney beds may have been, if any one will only compare Agassiz’s own figure of Asterolepis ornata, Hichwald (‘Old Red,” tab. 30, fig. 5), with the plate No. 10 in Pander’s restoration of the same species (‘‘ Placodermen,” tab. 6, 1 Op. cit. tab. xxx. figs, 5, 6. 2 Op. eit. appendix, p. 152. 3 Das vollkommenste Hautskelet der bisher bekannten Thierreiche, Dorpat, 1856. 4 Quart. Journ, Geol. Soc. vol. xvi. 1859, p. 122. Dy. EL Traquair—Homosteus and Ooccosteus compared. 3 fig. 1), he will see that this specimen at least, far from having “no reference to Pterichthys,” is the median occipital plate of a very closely allied form indeed. Without injustice to the memory of Sir Philip Egerton, to whom paleichthyological science is indebted for so much valuable work, it is clear that he had not sufficiently gone into this question at least, as the fact above noted was dwelt upon by Pander himself (op. cit. p. 16). On the Continent, however, the name Homosteus, Asm., has been adopted for Hugh Miller’s fish, and reasons have also been found for maintaining Pterichthys and Asterolepis as distinct genera, in a supposed difference in the articulation of the arms. In the previous volume of this Magazin! J have shown that this supposed diagnostic mark is untenable, at the same time that I have sought to establish another on the mode of articulation of the anterior median dorsal plate. But Agassiz’s work, in which he classified ‘“ Asterolepis”” among his “ Coelacanthi,” a group generally equal to the Cycliferous Crosso- pterygii of more recent times, was the means of drawing Hugh Miller into mistakes of much greater importance than mere nomen- clature. Accordingly, as Pander pointed out, Miller attributed to _his Asterolepis “the teeth of Dendrodus and the scales of Glypto- lepis,” and made a very formidable creature out of it, ten to thirteen feet in length; indeed, referring one of the large Russian plates (Heterosteus, Asmuss) to the same genus, he calculated a length of eighteen to twenty-three feet for the entire fish. And his non- recognition of the true affinities of the creature led also to other mistakes in the identification of bones, to which allusion will be made in due course. By Asmuss Homosteus and Heterosteus were placed in a family by themselves, Chelonichthyda, in a somewhat heterogeneous group of “‘ Ganoidea loricata,” the other families herein included being Spatu- larida, Acipenserida, Coccosteida, Pterichthyda, and Cephalaspida. As regards Homosteus, though, as Pander remarks, it is wonderful how, without knowledge of Hugh Miller’s drawings or description, he was able to fit together the isolated plates at his disposal, yet, unacquainted with the orbits, he supposed the cuirass to belong ex- clusively to the body, and also entirely reversed its position on the animal. Pander, however, classified Momosteus in McCoy’s group of Placodermata and rightly gave it a place immediately after Coc- costeus, interpreting as its median dorsal plate the one considered by Hugh Miller to be a ‘“‘hyoid,” and supposed by him to occupy a place between the rami of the jaws. This supposed hyoid plate was known to Hugh Miller only in an isolated form, but it fell to the lot of the late Mr. John Miller, of Thurso, to record a specimen in which it occurred in its natural position on the back behind the head, and so with absolute certainly to confirm Pander’s view of the case. Mr. Jobn Miller’s collection having some years ago passed 1 Notes on the Nomenclature of the Fishes of the Old Red Sandstone, Grou. Mae. Dee. III. Vol. V. 1888, p. 508. 4 Dr. R. H. Traquair—Homosteus and Coccosteus compared. into the possession of the Museum of Science and Art, Edinburgh, I propose to make this, the most perfect specimen of Homusieus which has ever been found, the text of the following remarks on the genus. Along with Homosteus it may, however, be as well to re-examine the structure of Coccosteus itself as a basis of comparison. The reading of the cranial buckler of Coccosteus is much com- plicated by the fact that certain superficial grooves belonging to the lateral-line system are very conspicuous and apt to be mistaken for sutures, while the true sutures are visible with difficulty, and can only be made out in exceptionally well-preserved examples. They seem, indeed, to have almost entirely escaped the observation of Agassiz, as the lines on the head indicated on his restoration of Coccosteus (“Old Red,” tab. 6, fig. 4) belong almost without exception to the lateral-line system. The figures given by Hugh Miller (Quart. Journ. Geol. Soc. 1859, p. 129, and “ Footprints,” Ist ed. fig. 11), in which he attempts to reduce the plates of the cephalic shield of Coecosteus to the same plan as that of the bones of the top of the head in the Cod, are much better, inasmuch as many of the true sutures are given ; but it is also too plain that he also looked upon the superficial grooves as indicating the real boundaries of the plates which he considered as the homologues of the cranial roof-bones in osseous fishes. Pander’s interpretation, aithough his figures give both sets of lines on the upper surface with considerable though not perfect accuracy, is correct only as regards the hinder part of the buckler, his reading of the anterior half being hopelessly wrong, and consequently his elaborate com- parison with the arrangement in Asterolepis falls to the ground. By far the most correct restoration of the cranial shield of Coccosteus is that of Huxley,’ in which he omits the superficial grooves alto- gether, and in which the only faults I can find are of omission, viz. the non-recognition of the median suture between the two central plates which he letters as “frontal,” and of the pair of premaxillary bones on each side of that median bone in front, to which he applies the name “ premaxilla.”’ In Pl. I. Fig. 2 I have given a sketch of the head of Coccosteus decipiens, Ag., the superficial grooves being given in dotted, the sutures in continuous lines, and as regards the names I have applied to the bony plates, I have thought it best to use as few as possible which might lead the reader to infer that I considered them the morphological equivalents of the cranial bones of ordinary fishes. Posteriorly we have the trapezoidal median occipital plate (m. o.), flanked on each side by the triangular external occipital (e.0.). In front of these are the two central plates (c.), external to which and forming the antero-external margin of the buckler are three plates, marginal (m.), post-orbital (pt. o.), and pre-orbital (p. o.), the two latter forming the upper margin of the orbit. The two pre-orbitals come together in the middle line posteriorly only for a very short distance, in front of which they are separated by a narrow oval 1 Dec. Geol. Survey, x. p. 30. Dr. R. H. Traquair—Homosteus and Coccosteus compared. 5 space open anteriorly, and in this space is lodged, first a small elliptical plate, the posterior ethmoidal (p. e.) and the median limb or stalk of the anterior ethmoidal (a. e.). This latter bone, the “ pre- maxilla” of Huxley, is like a nail-head with a broken off stalk attached, the head forming the anterior point of the buckler, the stalk passing back between the pre-orbitals. On each side of it in front are the small nasal openings (n.), each being bounded externally by a small separate bone, the premawilla (p. ma.). The orbit is bounded below by the “paddle-shaped” bone (ma. Fig. 3) repre- senting the mazilla, which has a sort of resemblance to that in Palgoniscus, and to the posterior extremity of which is appended a small triangular plate (j.), the jugal or post-maxillary. Turning now to Homosteus, we shall find that Hugh Miller’s comparison of its cranial plates with those of Coccosteus is not so far amiss, of course, taking into account the faults of his reading of the buckler of the latter genus. In Fig. 1 I have sketched the configuration of the specimen of Homosteus, referred to by John Miller as having the dorsal plate in situ. Much of the bony sub- stance having splintered off from the “specimen ” itself, I have had a plaster impression taken from the ‘“ counterpart,” which con- sequently reproduces the details of the original in a very much more perfect manner, and from this model the drawing has been taken. And I may add that every detail of the buckler here given is corroborated by another splendid specimen, also from the collection of John Miller, in which, however, the dorsal plate has got dis- placed to one side. We find a wonderful correspondence in the arrangement of the bony plates, the differences appearing almost entirely due to the altered position of the eyes, and the assumption by the cranial shield of an antero-posteriorly elongated, instead of a broadly hexagonal figure. The median occipital (m. o.), preserving its trapezoidal shape, has become much elongated, as have also the external occipitals (e. 0.), while the centrals (¢.) have become much smaller in proportion, and have come to take part in the inner boundary of the orbit, more, however. on the upper than on the under aspect; they are also in contact in front with the posterior ethmoidal (pt. e.), the hinder angle of which is inserted in a notch between their anterior ex- tremities. The marginal (m.), also much elongated, is easily recognized ; but it is now alongside of, instead of in front of, the external occipital, and the post-orbital (pt. 0.) and pre-orbital (p. 0.) have altered their relation to the orbit in a strange fashion. Separating internally, so as to allow the central to come into the boundary of that opening, they have thrown out processes which unite externally, and so in Homosteus the orbits come to be entirely enclosed within the buckler, instead of being outside it, as in Coccosteus. The last plate to be noticed is the anterior ethmoidal (a. e.), which occupies a position at the front of the snout exactly as in Coccosteus, but no trace is seen either of the small pre- maxillary, or of the nasal openings of that genus. 6 Dr. R. H. Traquair—Homosteus and Coccosteus compared. The lateral-line system of grooves is sparingly developed on the cranial shield of Homosteus. On each side the lateral groove passes along the external occipital and the marginal on to the post-orbital, where it divides into two branches, one of which passes outwards and forwards to the margin of the shield, while the other passes backwards and inwards to be lost near the middle of the central plate. If we compare this arrangement with that in Coccosteus (Fig. 2), we shall see that the plan is quite the same, although the extent of the groove-system is considerably diminished. The facial bones of Homosteus are extremely difficult of determi- nation, and I must frankly confess that I have come to no certain conclusions regarding them. In the specimen represented in Pl. I. Fig. 1 are three detached bones, a, B, and co, on each side of the anterior part of the cranium, by which B and ¢ are also partly con- cealed, while on the right side the bone a is seen only in longi- tudinal section, having stood on edge to the bedding of the rock. When those bones are seen in connection with examples of the buckler, they alway occur in the same order, and isolated specimens of all of them are also in the collection of the Edinburgh Museum. The bone 4 is broadest behind the middle, narrowest at each end, especially the anterior one. In the specimen here figured it is seen from the internal aspect, having apparently got turned over; but other specimens show that on the external aspect near the middle it had a patch of the usual tuberculation, with a short lateral-line system groove. This bone is figured by Hugh Miller as “ lateral cerebral plate,” but as many specimens in the collection show that its position was immediately below the edge of the antero-lateral portion of the buckler external to the orbit, the groove on its surface being a continuation of the transverse branch on the post-orbital, it is clearly the homologue of the paddle-shaped bone or mazilla in Coccosteus (Fig. 5). If this be the case then, we may assume that the bone B, following and parallel to it, is the mandible; but no traces of teeth can be found on either, or, indeed, on any bone which it is safe to refer to Homosteus. Like the Sturgeon it must have been edentulous. The bone c is figured by Hugh Miller (Footprinis, fig. 45a) as a clavical (here he meant what we now call post-clavicle) ; but, of course, such an interpretation founded on its superficial resemblance to the post-clavical of a modern Teleostean is here negatived by its position. Hugh Miller noticed the tuberculation of the outer side of one of its extremities, but in accordance with his theory of its position in the animal, he assumed this tuberculated portion to be its “head,” or anterior extremity. The present specimen shows, how- ever, that this extremity was posterior. The last and crowning point of interest in the specimen repre- sented in Pl. I. Fig. 1, is the exhibition of the dorsal cuirass in situ. Five plates are here seen, one median and two lateral, corresponding exactly to plates occupying a similar position in Coccosteus. The central dorsal plate (m. d.) is so well known as Hugh Miller’s Dr. R. H. Traquair—Homosteus and Coccosteus ‘compared. 7 supposed “hyoid,” that it requires no further description, beyond the remark that its resemblance to that of Coccosteus, except in its short broad shape and the want of the posterior elongated peak, must be evident at the first glance. It is here shown in position, its broad margin being directed forwards, and lying parallel to the posterior margin of the cranium, from which it is here separated by a narrow gap, its obtuse point being free and posterior. Its lateral margins overlap on each side two other bones, of which the anterior one (a. d. 1.) was figured by Hugh Miller as “non-descript latero-hyoidal plate,” he being well aware of its relation to the median bone, though, in accordance with his theory of the latter, he reversed its position. Its relation to the skull was, however, correctly represented by Pander (‘‘ Placodermen,” tab. 8, fig. 2a.). Jt consists of two parts, one flattened above, and applied anteriorly to the outer part of the posterior margin of the skull, by which as well as by the median plate it is overlapped, and another, narrower, forming a right angle to the flattened portion and running forwards a little way along the posterior part of the outer margin of the cranial buckler; in the angle between the two parts is a socket for articulation with a corresponding projection of the postero-external angle of the external occipital. Naturally Hugh Miller found him- self at a loss to account for the presence of this socket. Different as the two bones are in shape, it is impossible not to recognize in this bone the homologue of the anterior dorso-lateral in Coccosteus (Fig. 3), though here the socket and peg have changed their positions on the bones concerned. Behind this anterior dorso-lateral there exists in the specimen figured in Pl. I. Fig. 1, another and much smaller plate (yp. d. I.) on each side, which has not previously been noticed. It needs no reasoning to perceive at once that this is the posterior dorso-lateral of Coccosteus (p. d.1., Fig. 3). It is curious that no undoubted remains of a ventral body-carapace like that of Coccosteus have occurred in connection with Homosteus ; but, at the same time, I might mention that the plate (Footprints, fig. 37) designated “palatal plate” by Hugh Miller, looks to me as if it might well be the anterior median ventral, so far as its shape is concerned, though its great size may be considered as somewhat against the supposition. At all events there is no evidence for referring it to the palate. There are also several other bones figured by Hugh Miller and contained in the Edinburgh Museum, which from the way in which they occur, associated with other undoubted remains of Homosteus, clearly belong to the same fish, but whose position in the body I cannot speculate upon. ‘These are the “operculum” (Footprints, oth edition, fig. 39), the very curious bone (ib. fig. 43) spoken of by Hugh Miller, as “shoulder (i.e. coracoid?) plate”; his so-called “dermal bones” (ib. fig. 44). What the bones ¢ and e in fig. 46 of the “‘ Footprints ” are I am also unable to determine. But a number of the other remains figured in the “ Footprints ” as “ Asterolepis” belong not to Homosteus, but to Glyptolepis 8 Prof. Hughes—Lower Cambrian, Bethesda, N. Wales. paucidens, Ag: sp. These are the scales (figs. 26 and 27), the mandibles (figs. 82, 33, and 386), the sections of teeth (figs. 84 and 35) ; the bone d (fig. 46), which I look upon as the lower end of the clavicle; and the interspinous piece (fig. 48), which Hugh Miller figured as the “ischium of Asterolepis.” The latter is indeed a very curious bone, and it is not at all remarkable that the author of the “ Footprints” should have sought to identify it with the basal bone of a ventral fin constructed in teleostean fashion. Knowing that such a pelvic fin-element could hardly have existed in either Homosteus or Glyptolepis, the bone was long a puzzle to me, until one day I observed a very similar bone supporting the distal set of interspinous bones of the second dorsal fin in a specimen of Glyptolepis leptopterus, also in the Hugh Miller Col- lection. A similar bone supporting three smaller interspinous elements was described and figured by Sir Philip Egerton in Trists- chopterus.} As regards the species of Homosteus, which has been under con- sideration, no specific name was given to it by Hugh Miller. By Morris? it was catalogued as the ‘‘ Asterolepis Asmusii” of Agassiz, but I know not on what ground. Certainly I can find no resem- blance between the sculpture of the surface of the plates of A. Asmusit, as given in Agassiz’s figures, and that which characterizes the present fish in which the tubercles are small, sharply defined, with prominently stellate bases, and for the most part closely placed. Nor can it be identified with the species of Homosteus described by Asmuss from Dorpat, and so I would propose that for the future it be known as Homosteus Milleri. EXPLANATION OF PLATE I. (In all the figures the same letters refer to the same things.) m. 0. median occipital. e. o. external occipital. mm. marginal. c¢. central. pf. o. post-orbital. y. o. pre-orbital. pé. e. posterior ethmoidal. a. ¢. anterior ethmoidal. y. maz. premaxillary. m. nasal opening. m. d. median dorsal. a. d. 1, anterior dorso-lateral. yp. d. J. posterior dorso-lateral. a. /. anterior lateral. yp. 7. posterior lateral. 7. 7. interlateral. «@. v. /. anterior ventro- lateral. yp. v. 2. posterior ventro-lateral. mm. v. posterior median ventral. A, B, C, three facial plates lying below the margin, anteriorly of the cranial shield of Homosteus. Fie. 1. Sketch of a specimen of Homosteus Miller’, Traq., in the John Miller Col- lection, Museum of Science and Art, Edinburgh. Fre. 2. Restoration of the top of the head in Coccosteus decipiens, Ag. The dotted lines indicate the distribution of the grooves of the lateral-line system. Fic. 3, Sketch of a specimen of Coccostews minor, H. Miller, from Thurso, the vertebral column omitted. Hugh Miller Collection. IJ.—Nore on tut Lower CamBriaANn OF Betusespa, Norta WALES. By Prefessor T. McKrnny Hucues, M.A., F.G.S. NTIL quite lately no fossils had been found in the Lower Cambrian of Bethesda. Indeed we had almost given up the hope of obtaining any evidence of the life of the period represented by them, because of the great alteration in the character of the rock resulting from the severe mechanical action to which it had been _ 1 Dee. Geol. Survey, vol. x. p, 52, plate 5. | * Catalogue British Fossils, p. 318.; 5°On Plate I. in Fig. 2, for p.e. read pt.e. In Fig. 3, for e.m. read e.0. ¥ ‘ Prof. Hughes—Lower Cambrian, Bethesda, N. Wales. 9 subjected. The announcement that Mr. Robert Lloyd had discovered fossils in the uppermost slate beds of the Penrhyn Quarries was therefore received with great interest, which was increased when it was found that some of these were in a sufficiently perfect state for determination, and that they were referred by Dr. Woodward' to a new species of a well-known Lower Cambrian genus of Trilobite. I have since found fragments of another smaller species in the same beds not far below the Bronllwyd grit. The zeal of Mr. Robert Lloyd, to whom I am indebted for much valuable information, especially with reference to the subdivisions and measurements of the Penrhyn Slates, has recently been rewarded by the discovery of traces of fossils in the part of the quarry known as Sebastopol, some 1200 feet lower in the quarry than the Conocoryphe. viola zone. Unfortunately these specimens also are too obscure for determina- tion. ‘They appear to be the casts of the carapace of a Trilobite filled with radiating mineral matter, and are of somewhat the same size and outline as those of Conocoryphe viola. I have thought it might be of interest to offer a few notes on the rocks seen in a traverse from a point a little west of Bethesda across the Penrhyn Quarries over Moel Perfedd to Cwmbual on the south, with a view to fixing the position of the only fossil zones yet known in that area, and pointing out the localities where it seems most probable that fossils may yet be found. The accompanying diagram section will facilitate reference :— MOEL PERFEDD CARNEDD 2 Y FILIAST BRONLLWYD eo PENRHYN cwM aw i . ri CEUNANT POSSE QUARRIES ST. ANN’s GHAPEL | Hi h | ji li! h © DOLOWEN TAINEWYDDION Fic. I.—Diagram Section N.N.W. and §.S.E. from St. Ann’s Chapel to Moel Perfedd. Length of Section 2} miles. The cleavage is nearly vertical N.N.E. and 8.8. W. * Indicates horizons at which fossils have been found. A. The slates south of Moel Perfedd are dark grey irregularly cleaved lumpy sandy beds which at one place dip at an angle of about 40° to the north, that is, towards the felspathic rock. B. This felspathic rock behaves as an intrusive mass. It is not seen down the hill side to the bottom of the valley. é C. Black and grey slaty rock fills up the interval between Moel Perfedd and Carnedd Filiast. In this Cwm Graianog has its origin. D. The grit of Carnedd Filiast is inclined at a high angle and runs down the north side of Cwm Graianog protruding in rough bosses near Tainewyddion. Here it is split up by finer beds upon the face of which Cruziana semiplicata is abundant. 1 Quart. Journ. Geol. Soc. vol. xliv. pp. 74-78, pl. iv. 1888. 10 = Prof. Hughes—Lower Cambrian, Bethesda, N. Wales. _ In the talus under the cliff above Tainewyddion I found several specimens of Lingulella Davisiti in a grey or yellow flag similar to that which occurs subordinate to the Carnedd Filiast grit. We are here evidently in the Middle Lingula Flags, which is repre- sented chiefly by massive coarse grit. When we wander south into the district west of Arenig, there are still beds of strong grit at this horizon, but they are thin and quite subordinate to the flags and slates. The shore line was further north, and therefore in that direction we may expect to find the rocks of this age either repre- sented entirely by shore deposits or overlapped against the rising ground by the newer part of the series. . Below the Filiast grit we should search for Lower Lingula and Menevian, and we shall see that there are black slates about that horizon from which as yet no fossils have been recorded. #. Between Carnedd Filiast and Bronllwyd there is a depression which, further east, forms the head of Cwm Ceunant. This hollow is due te the occurrence here of a soft pale grey and white irregularly cleaved sandy slate. It seems to be in the line of the softer rock which runs through the gap between Hlidrfawr and the rocky hill which rises from Marchlyn Bach on the west. These slaty beds pass up into the sandstone and grit of Carnedd Filiast and down into the grit of Bronllwyd. A soft black slate is seen in this division above Pengareg ; any part of this series might be expected to yield fossils and it is here we should search for Lower Lingula Flags and Menevian. F. The grit of Bronllwyd, which comes next in descending order, and rests immediately upon the Penrhyn slate, consists chiefly of a quartz grit and conglomerate, containing fragments, generally about the size of a pea. It passes into banded grit and sandstone, with beds conspicuously mottled black and grey, the black being due to large mudpans, and included masses of shale pinched up in it, so as to occur very irregularly through what otherwise appear to be somewhat evenly lying beds. ‘This proves that a con- siderable amount of deformation often takes place even in a massive grit. The alteration of a grit by cleavage into a schistose quartz vock is well known, but this fold and fault deformation is also clearly a common phenomenon. The Bronllwyd grit is of great thickness, and rolls over rapidly to the south-east, a dip of 55° being observed in one place above the Penrhyn Quarry. G. The Penrhyn slates, which next succeed in descending order, are wonderfully uniform in character throughout, but yet a close observation of those small differences which affect the quality of the slate has called attention to slight variations of texture, as well as the more marked difference of colour, and enable us to make out the fallowing subdivisions :— a. Immediately below the Bronllwyd grit is a glossy light apple- green slate, somewhat like a hone stone in character. It is a useful slate, and was used for the roof of the new church at Bethesda. It has not been much worked, except in one quarry, known as Crimea, Prof. Hughes—Lower Cambrian, Bethesda, N. Wales. 11 a name much in people’s minds at the time it was opened. In this quarry the new Trilobite, Conocoryphe viola, Woodward, was found by Mr. Lloyd. I verified its occurrence by finding several specimens myself. I have been able to add also another smaller species of Trilobite, but my specimens are too fragmentary for determination. There is also not uncommon in these beds a rounded pear-shaped body, with a granular texture and banded structure, perhaps some form of sponge. There are hardly any indications of bedding, except the regular roof of grit and the constant but less regularly occurring purple slates below. There are a few sandy lines and bands, which, however, can rarely be followed for more than a foot or so. The fossils appear on distorted bed faces, generally lying within 5° or 10° of the cleavage planes. These beds are locally known as the Upper Green Slate, Maenty- gwyrdd uchaf, or Cerrig Ilwydion, and the estimated thickness is 120 feet. The Upper Green Slate passes down into the next subdivision. b. Purple Slate. The way in which this comes on shows that the colour does no go for much, as it occurs in a blotchy irregular manner, suggestive rather of local circumstances affecting the iron in the rock at any time subsequent to its deposition. It has often a silky texture; this character being seized upon by the workmen, who called it the Silky Vein, or Cerig Rhiwiog, as distinguishing it from the more sandy and irregular mass of slate below. It is of about the same thickness as the Upper Green Slate, viz. some 120 feet. c. A coarser and less evenly cleaved rock which is called Bastard slate, and is said to be in thickness about 850 feet. d. The old blue slate, so called first because it was one of the earliest quarried, and next because of its colour. The colour is, however, more green than what we should understand by blue when applied to a slate. This difference is lost in the Welsh name Careglas.. It is in the upper part of this band that the traces of fossils have been recently found in the working known as Sebastopol, according to Mr. Lloyd’s estimate, some 1200 feet lower than the Crimea quarry, or zone of Conocoryphe viola. e. A bed of red gritty rock, known as Gwenithfaengoch, about 16 feet in thickness, separates this slate from _ jf. The Lower Purple Slate, Cerig Cochion, which attains a thick- ness of 300 feet, and passes down through g. About 240 feet of veined slate, known as Cerig gleision gwythienog, into h. The Lower Green Slate, Gwyrdd isaf, in which there is some 300 feet of workable slate. H. Greenish sandy beds, with included fragments of older rock, are just touched at the bottom of the quarry. These are probably the top of the passage beds into the schistose fragmental rock, which is associated with K. The cleaved grit and conglomerate, seen near the bridge, south of Bethesda. 12. Prof. Hughes—Lower Cambrian, Bethesda, N. Wales. I. Below these come the slates of the Tramway cutting, to be more fully described in illustration of the chief point of this com- munication, viz. the nature of the deformations which have taken place in the Penrhyn slates, and their bearing upon the manner of occurrence of fossils in different parts of the series. . M. To the north of these the St. Anns Grit crops out. It was touched in breaking ground for the new brickworks near St. Anns, and was quarried for use in some of the buildings connected with them. It contains numerous and conspicuous grains of hyaline quartz, as well as of pink quartz and jasper, in this resembling the Cambrian grits of the Bangor-Carnarvon area. Such is the succession of rocks seen south of Bethesda. There is no proof here of a repetition by complete inversion of any large portion—though the rocks have been much crushed up in detail. One of the various difficult questions raised by the examination of this district is, What were the conditions which favoured the pre- servation of fossils only here and there in this great thickness of rock? The first and most obvious reason which suggested itself was that the great unyielding mass of the Bronllwyd Grit, imme- diately below which the fossils occurred, saved the underlying bed from the severity of the crush, and that the finer rock therefore split along bedding planes parallel to the base of the grit. An examination of the section, however, soon showed that this explana- tion would not hold: for the fine green rock is strongly cleaved tight up to the base of the grit, and the grit itself has evidently suffered much in the crush, as shown by the squeezed-up mudpans and the contortions of the finer parts. Moreover, if the occurrence of fossils 1200 feet lower down in the quarry and far from any unyielding mass of grit be verified, we must seek some other reason for the exceptional preservation of such traces. When in the quarry we endeavour to seek an explanation, we notice first that the fossils do not occur in the planes of bedding as inferred from the lie of the large consecutive masses of rock of different lithological character. Yet the fossils can never have been of such rigidity as to have been thrust into approximate coincidence with the planes of cleavage during the crush which produced it. Further we observe that there are no bands or lines suggestive of stratification running parallel to the dip inferred from the alter- nating beds of grits and slates. Any such bands and lines are irregular, interrupted, of small extent, and at all angles to the constant cleavage. Tn rocks of such a uniform character as the Penrhyn Slates the relative displacement of parts is never easy of detection. If, how- ever, we follow them to where some of the beds are picked out by differences of colour and texture, so that we can disentangle the complications, we get a clue to the processes by which the rock has been reduced to its present state, and an explanation of the irregular manner of occurrence of the fossils. In the Tramway cutting for instance, between the St. Ann’s Road and the Quarries, we see that the bands which here mark bedding are twisted, drawn out, doubled Prof. Hughes— Lower Cambrian, Bethesda, N. Wales. 13 © back, interrupted, and repeated, in every variety of fold and break— of which examples are given in the subjoined woodcut, Fig. II. Fie. IT. my \ if a i a aN d Ks ui | wi The selection shows three stages of the same class of movements, where the folds are more conspicuous in the first and the faults in the last, so that in it portions of the folds are faulted out of the field of view altogether. This is not cleavage, nor necessarily con- nected with cleavage, and on this distinction 1 would lay particular stress. Many rocks, such as the gnarled series of Anglesea and parts of the Devonian of Devonshire, show the fault and fold structure with inconspicuous cleavage. This is the action which produces schistosity in all sorts of rock, modified, of course, by its original character, whether, for instance, it is a soft rock with sub- ordinate hard beds, or a somewhat uniform mass with veins. The essential character of the fold and fault structure being that there is a relative displacement of considerable portions of the mass, pro- ducing what I have elsewhere called a universal slickenside. The essential character of cleavage being that there is no such dis- placement of considerable portions of the rock, but only a molecular rearrangement producing a tendency to split along an indefinite number of parallel planes. Cleavage may affect a rock in which the bedding planes are not 14. Prof. Hughes—Lower Cambrian, Bethesda, N. Wales. contorted, so that fossils are often found along an even line on the | edges of the cleavage planes. : Cleavage may be superinduced upon a rock already affected by fault and fold structure, especially in a rock of a fine and homo- geneous character, and this is what seems to have taken place in the case of the Penrhyn Slates. Doubts as to the nature of cleavage may often be traced to the want of a clear distinction between these two superinduced struc- tures—the molecular rearrangement due to cleavage and the kneading of the mass with fault and fold schism. Why pressure should in one case crumple up the beds and in another make them yield as a plastic body, is a separate question probably capable of receiving different correct answers in different cases. What we are aiming at now is the establishment of the fact that there is this two-fold action, and resulting different structure, and the application of it to the explanation of some stratigraphical difficulties. In these lower Penrhyn Slates the direction of displacement of well-marked beds is not even generally coincident with cleavage. We see here evidence that there is not only a thickening of homo- geneous masses by molecular movement approximately at right angles to the direction of pressure as indicated by the cleavage, but also a folding and crumpling of the beds, so that one layer is repeated three or four times in the same vertical section. Thus we get a suggestion of the reason why fossils may be found only here and there in a rock-mass which appears to be throughout of a similar character and to have been subjected to similar con- ditions. The cleavage often leaves the fossils on planes along which the rock will not split, at the same time distorting them beyond the possibility of recognition in small fragments. But when the rock has been crumpled and folded previous to or coincidently with the cleavage, some specimens here and there will lie on faces which have suffered less deformation or coincide with easy divisional planes. The great rock-masses near Bethesda roll away in great undu- lations, having a general dip to the south and east; but subordinate masses are puckered, behaving under this enormous pressure as if plastic, the greater surface extension being compensated by dimi- nished thickness and vice versd. . Ramsay! pointed out that the vertical extent of some of these beds was probably greatly in excess of their original thickness. This kind of thing is, of course, most likely to occur in such cases as that which we are considering, where the newer beds abut against an axis of older rocks which have been already squeezed and shrunk beyond the possibility of much further com- pression, just as in a crowd the man who is jammed against the wall or post gets most hurt. We further notice that along the old Archzan axes two things happen which account for a very rapid disappearance of beds which are seen to be of great thickness in a closely adjoining area. 1 Mem, Geol, Survey, vol. iti, pp. 190-196. Alfred Harker—Physics of Metamorphism. 15 There is first the accumulation in the hollows and an overlap of the later over the younger part of the same series as the successive deposits creep up the flanks of the submerged land. And, secondly, there is the exaggeration of the thickmess of the mud accumulated in the hollows when pressure supervenes and squeezes it up against the base of the cliffs and steep mountain chains of the ancient submerged land. Thus the manner of occurrence of the fossils in the Penrhyn quarry throws some additional light on the processes which have modified the older rocks even to the exaggeration of thickness. There is not such a great difference in the thickness of the lowest part of the series at Bethesda and Bangor, and even that difference can be much reduced by allowing for the increase in the apparent thickness of the Penrhyn slates by squeeze. The still greater missing series at Carnarvon may be accounted for by the overlap of higher over lower Cambrian against an important sea-bordering Archean mountain range. The lowest Cambrian beds at Carnarvon were thus a higher and newer part of the system, and being nearer the tops of the mountain ridges escaped the great crush that caught the older and deeper beds thrown down nearer the base of the ancient range. IIJ.—Nortes on tHe Puysics or MrTamorpHism. By Atrrep Harker, M.A., F.G.S., Fellow of St. John’s College, Cambridge. HE problem of the metamorphism of rock-masses is one in which increased study has not led to unanimity of opinion. The literature of the recent Geological Congress in London suffices to remind us, how widely divergent are the conclusions to which various geologists have been led by researches in the field. Since, then, the a posteriori line gives such very different results in different hands, it may be worth while to revert for a moment to the deductive method, and try to trace the consequences, in this connexion, of admitted physical principles. Since some definition of our subject is necessary, we will, for the present purpose, group together under the name metamorphism all processes which result in a partial or complete crystallization or re-crystallization of solid masses of rocks. Such changes are usually effected through chemical re-arrangements, and are often attended by the development or creation of special structural planes in the rock-masses. ‘Those processes which do not appear to demand either a high temperature or a high pressure, such as the conversion of sandstone into quartzite by deposition of interstitial quartz, although logically included here, will not be discussed. We may conveniently distinguish them as hydro-metamorphism, recognizing the important part played by water in changes of this kind. The geological manuals lay down a fundamental distinction between contact- and regional-metamorphism ; but from our present starting-point we arrive at a somewhat different division. It is 16 Alfred Harker—Physics of Metamorphism. indeed evident that what is essential to contact-metamorphism is not the proximity of an eruptive mass, but simply an elevation of temperature ; and, so far as chemical and mineralogical changes are concerned, it is immaterial whether the heat be conducted from some neighbouring source or generated in situ by mechanical or other means. It appears, again, from the writings of many geologists who invoke the operation of mechanical force in explanation of meta- morphism, that they require nothing of that agent beyond the generation of heat by the crushing of the rocks operated upon. A theory based on these lines fails to show any cause for difference between the results of dynamical and of contact-metamorphism. That differences of kind exist, is, however, generally admitted. Certain minerals, such as andalusite, tourmaline, garnet, and idocrase, are known to be especially associated with the alteration of stratified rocks at high temperatures. On the other hand, there are changes, such as the amphibolisation of pyroxene, the saussuritisation of plagioclase, the conversion of potash-felspar into white mica and quartz, and the production of sphene at the expense of titaniferous iron ores, which are characteristic of altered rocks showing clear evidence of mechanical stress. These two phases of metamorphism by no means exhaust the possibilities, but they apparently compel us at the outset to recognize as distinct from one another a thermo- and a dynamo-metamorphism, the pressure in the latter case operating not through the medium of heat generated, but immediately. In short, we must admit the direcé correlation between mechanical and chemical energy, to which experimental results unmistakably point. While allowing the potency of pressure as a factor in geological transformations, many writers seem reluctant to admit it to a rank co-ordinate with temperature, as one of the conditions governing all chemical processes. They quote the experiments of Mallet, but overlook those of Cailletet and Spring. But if the chemist can, for the most, neglect in practice the effects of variations of pressure on solid bodies, it is only because the range of pressure in his experi- ments is comparatively small: the laboratory of nature knows no such restrictions. In parts of the earth’s crust with which geological research is concerned, there must be enormous pressure, as well as extreme temperature; and these two, though often locally coinciding, must be physically independent. For rough purposes we may separate four sets of conditions, which may exist in various places, and which may be expected to govern the atomic forces in different manners, giving rise in their several provinces to different chemical combinations : (i). Low temperature and low pressure (hydro-metamorphism). (ii). High temperature and low pressure (thermo-metamorphism). (iii). Low temperature and high pressure (dynamo-metamorphism). (iv). High temperature and high pressure (p/atono-metamorphism). The first, in the widest sense, will embrace various chemical changes which go on chiefly near the surface of the earth. The second will be typically represented by ‘contact-metamorphism,’ but will also include cases in which the crushing of rocks under a Alfred Harker—Physics of Metamorphism. 17 moderate pressure gives rise to the generation of heat sufficient to produce a considerable rise of temperature. The third set of con- ’ ditions will be best exemplified when pressure acts on a rock-mass not rigid enough to offer great resistance to crushing. A good illustration of its effects is seen in satiny slates or phyllades, such as those of Fumay, and perhaps of Llanberis and Michigan. These rocks, distinguished from mere clay-slates, must in some cases be classed as highly metamorphic. ‘They appear to consist largely of authigenic minerals, and their highly-developed cleavage-structure is in fact a micro-foliation. By applying to various districts of altered rocks this distinction of thermo- and dynamo-metamorphism, that is, by considering the proximate instead of the mediate causes of the chemical trans- formations, we may possibly find a clue to some apparent anomalies. One of these is the interpolation of thermo-metamorphic rocks in the midst of a region of dynamo-metamorphism. Such are the puzzling cornéites (composed of biotite and quartz), the garnetiferous and other special rocks of the Remagne and Bastogne district in the Belgian Ardenne. Their peculiarity seems readily to connect itself with the facts that they occur in the cores of anticlinal folds, where they must have been crushed upon themselves, and that the rocks thus affected, unlike their neighbours, are hard beds which would offer resistance to the deformation, and so give rise to the generation of heat. It is not to be expected, however, that the varied mineralogical phenomena of a great metamorphic region will in general divide themselves into those due to high temperature and those due to high pressure. We have still to reckon with the case of great heat produced by the crushing of large masses of hard rocks under a pressure itself sufficient to modify materially the chemical affinities. The results produced by the superposition of thermo- and dynamo- metamorphism must be very complex: but we have no reason to suppose that these are comparable in any special way with the effects of a very high temperature and an intense pressure operating simul- taneously. Indeed we must recognize in this latter a problem to which we can bring no direct experimental knowledge. Rocks which have been subjected to such conditions may presumably assimilate in some respects to those solidified from fusion under similar circumstances, although we should expect differences of textural and structural characters between the two. Failing a better name, we may accordingly use the term plutono-metamorphism to describe the profound changes in rocks implied in the joint influence of very elevated temperature and enormous pressure. Experiments in the artificial reproduction of minerals have led geologists to lay stress on the presence of water during the trans- formation of rocks. This question does not touch the fourfold division suggested above. ‘The temperature and the pressure must in general’ completely define the conditions of the chemical pro- * The exceptions being fusion and solidification, which cannot fairly be classed with metamorphism, DECADE Iil.—VOL. VI.—NO. I. 2 18 Alfred Harker—Physics of Metamorphism. cesses involved (local solution, crystallization, etc., being included as chemical changes) : water, if present, is one of the substances in which the recombinations are induced; in other words, a part of - the rock. In pure thermo-metamorphism it is probable that the expulsion of contained water is the first effect of the rise of temper- ature, and observations show that this is true even of the liquid enclosed in the minute pores of crystals. High pressure acting ‘upon rocks containing water will, as appears from theory and ex- periment, assist solution, but retard the complementary process of crystallization from solution. An important case will be that of a heterogeneous rock-mass in which the pressure varies from point to point. Here the solution of minerals at the points of maximum pressure, and their deposition where the pressure is least, must be a factor of great potency in the transformation of the rocks. Indeed this action, first pointed out by Sorby, may have a very important application to the separation of the several constituent minerals, and their segregation into lenticular streaks, which mark a common type of crystalline schists. As is indicated by the last suggestion, the structural cannot be strictly separated from the chemical effects of pressure. Such separate consideration is to some extent possible only with comparatively soft rocks, which do not offer great resistance to deformation. In such cases it is useful to remember that a pressure in a definite direction is mathematically equivalent to a uniform pressure together with certain shearing stresses. Of these the former tends to produce a change of volume without change of shape, i.e. a uniform com- pression, the latter a change of shape without change of volume, 1.e.a Shear. Both these changes involve an expenditure of mechanical energy, but the energy expended in shearing will be small in the case of a soft rock. ‘The term shear is here used to describe a con- tinuous deformation, not a disruption. This seems a legitimate adaptation of the mathematical word, although since rocks are heterogeneous bodies, their “‘ shearing” presents only a geometrical, not a physical, analogy to the shearing of elastic and viscous sub- stances. In this useful sense the expression was introduced into geological literature by Mr. Fisher only four years ago, and it is to be regretted that it has been so soon perverted by those who apply it to discontinuous sliding or faulting. We frequently find it stated, or assumed, that when structures such as cleavage or foliation are set up in a rock-mass by shearing, they are parallel to the direction of shearing ; although, as has often been pointed out, they must really be perpendicular to the maximum linear compression. In other words, these structural planes are parallel to the chief diametral plane of the strain-ellipsoid, while the shearing-planes, if they remain constant in direction, are parallel to cyclic sections of theellipsoid. Only for a large amount of shearing will the shearing-planes and the induced structural-planes become nearly parallel. In a rock of considerable rigidity, shearing as well as compression involves the expenditure of mechanical energy, which must be Alfred Harker—Physics of Metamorphism. 19 converted into heat or chemical energy or both, and so contribute to the chemical part of the metamorphism. There is another case which must be to a certain extent realized by some rocks, and which we may picture as that of a mass consist- ing of grains individually rigid, but capable of sliding upon one another. This is the “granular medium” investigated by Professor O. Reynolds.1_ Here a pure shear is impossible, since any change of shape in the whole, effected by rearrangement among the grains, involves a change of total bulk. If such a mass has already been “packed” into a state of minimum volume (not necessarily the least possible volume), any deformation will increase its bulk, and so will be resisted by the pressure. Such a condition could be per- manently relieved only by chemical action, beginning perhaps by the solution of the grains at their points of contact. It appears too that the intercalation among more yielding materials of a granular rock, which becomes in places ‘“‘ packed” to a minimum volume, will often determine internal disruption and faulting of the mass. The relation between foliation and the banded or gneissic structure is a question which need only be referred to briefly. When the latter is produced by the same prime agent as the former, as for example in the manner described by Mr. Teall,’ the two structures will necessarily be parallel to one another. But when foliation is set up by dynamical agency in rock-masses possessing a previous banded structure, whether from stratification, or earlier metamorphism, or any other cause, the former will not of necessity be parallel to the latter, although it will tend to become so with increasing deformation. Numerous examples of foliation oblique to gneissic structure have been described and figured.* For the sake of clear- ness, it does not seem advisable to name this peculiarity ‘double foliation.” If we use the term foliation strictly with reference to the intimate structure of the rock, and not to alternations of different petrological types, a rock-mass cannot present two foliations in the same place: the second will destroy the first as a direction of true schistosity. The same is true of slaty cleavage, notwithstanding various statements to the contrary. I have examined numerous examples of the local phenomenon styled “double cleavage” in the Ardennes, and in all cases resolved the second set of structural planes into a false (or ausweichungs-)cleavage, {consisting in a succession of minute folds or faults of the kind figured by Heim, Reusch, and others. The “cross-cleavage” of Wales and the Lake District appears to be merely a fine jointing. In conclusion, it may be well to remark that the analysis of internal forces into uniform pressure and shearing stresses is quite general. Such ideas as torsion or wrench on a screw do not import 1 Phil. Mag. ser. 5, vol. xx. p. 469, 1880. 2 Grou. Mac. 1887, p. 484. 3 Q.J.G.S. vol. xliv. p. 898; 1888: Reusch, Krystallinischen Schiefer, pp. 74 and 115; 1883. 4 Mecanismus der Gebirgsbildung, plate xv. figs. 8 and 11; 1878: Krystallin- ischen Schiefer, p. 51; 1883: Bémmeloen og Karméen, p. 196; 1888: Report Brit. Assoc. for 1885, pp. 838 and 840. 20 : Prof. C. Lapworth—Ballantrae Rocks of South Scotland. anything new with respect to the conditions of rock-transformation. They express usefully theories as to the distribution of mechanical stress and its induced metamorphism, but do not give rise to any new kind of metamorphic processes. IV.—On toe BaitantraE Rocks or Sourn ScornanD AND THEIR PLACE IN THE UPLAND SEQUENCE. By Pror. Cuartes Lapwortu, LLD., F.R.S., F.G.S. Part I.—The Ballantrae Rocks. N the extreme north-west flank of the Lower Paleozoic region of the Southern Uplands of Scotland there occurs a remarkable coastal area of stratified, igneous and altered rocks, known to geologists as the ‘‘ Ballantrae Rocks,” from the little fishing town of Ballantrae, which is built upon them. They range along the shores of the Firth of Clyde for a distance of about 12 miles, and are well displayed in section in a series of rugged cliffs cut through by the picturesque coast road between Ballantrae and Girvan. The area they occupy nowhere exceeds five miles in width, and is limited inland by the smoother regions floored by the barren greywackés of the Uplands and the fossiliferous strata of the Girvan district, but this inland boundary is everywhere curiously broken and irregular. The rocks occurring within the limits of the Ballantrae district consist of—(a) conglomerates, limestones, shales, quartzose flag- stones, and volcanic grits and tuffs; (6) broad sheets of serpentine, porphyrite, and various crystalline rocks; and (c) irregular masses of gabbro, diabase, and dolerite. Of the mutual relationships and true systematic position of these rocks, very diverse views have been advocated by geologists. Some of the unaltered limestones within the Ballantrae area were proved by Mr. Carrick Moore,! as early as 1848, to contain the same fossils as the well-known lime- stones of the Stinchar valley (and consequently to be of Llandeilo- Bala age). Since that date a few additional fossils have been recorded from the rocks of the area,’ but these have all been procured from the same well-marked limestone zone. The presence of these Llandeilo-Bala fossils in the limestones of the Ballantrae district has been very naturally held by most geologists as fixing generally the geological date of the associated stratified, igneous, and altered rocks. By some this deduction has been carried out fully, and the whole of the Ballantrae rocks have been described as Bala beds in various stages of metamorphism.® By others, however, while the Ballantrae rocks were placed, as a whole, with the Stinchar Limestones at the base of the fossiliferous Girvan sequence, some of their crystalline members were regarded as of igneous and eruptive origin.* Finally, others, who were aware of the faulted and convoluted character of the region, have suggested that some of its included rocks may be even of Pre-Cambrian age.° By myself the Ballantrae rocks have been looked upon as a 1 Q.J.GS. 1849, vol. v. pp. 7-17. * Explan. Geol. Sury. Scot. Sheet vii., p. 9. 3 J. Geikie, Q.J. 'G.S. 1866, vol. xxii. p. 5138-534. a Murchison, Siluria. 5th ed. p- 145, note. 5 Hicks, Q.J.G.S. 1882, vol. viii, p- 665. Prof. OC. Lapworth—Ballantrae Rocks of South Scotland. 21 complex formed of—(a) the Stinchar limestone and conglomerate series; (b) a stratiform series of sedimentary and volcanic rocks of much earlier date ; and (c) intruded igneous masses of subsequent but unknown geological age. When the first and last of these sections had been satisfactorily eliminated, I believed that the remainder—or Ballantrae series proper—would prove to be of higher antiquity than any of the fossiliferous strata hitherto recognized in the Southern Uplands.? In my paper? upon the Girvan succession the rocks of the Ballan- trae complex are thus referred to:—‘‘ These Girvan rocks (Llandeilo- Bala to Wenlock) appear to repose at their base upon the generally older igneous and altered rocks of Ballantrae. The Ballantrae rocks have as yet been too imperfectly studied to allow us to hazard any conclusion respecting their true geological age. That many of the rocks grouped together under this title are of far greater antiquity than the basement beds of the Girvan succession may be regarded as established by the fact that fragments of the Ballantrae rocks occur in the Kirkland or Purple conglomerate at the base of the Girvan succession. These (their) Pre-Girvan traps and ashes must either represent the Arenig and Llandeilo (Lower) volcanic rocks of Wales and Cumberland, or must be of more ancient date. On the other hand, rocks which are unquestionably of true Girvan age occur at many localities within the typical Ballantrae region itself, while the patches of altered or so-called Ballantrae rocks (of that memoir) found outside that area, as at Shallock Hill, Laggan Hill, and else- where, almost certainly include some greatly altered Girvan rocks.” The time at my disposal for working out the main object of my Girvan paper—namely, the determination of the natural order of succession among the fossiliferous rocks of the Girvan district—did not admit of my devoting more attention to the rocks of the Ballan- trae complex than was sufficient to establish their inferiority as a whole to the fossiliferous Girvan series. Hence all the rocks (sedi- mentary, igneous, and altered alike), whose position and characters showed that they formed a part of the heterogeneous Ballantrae com- plex, were provisionally grouped in that paper under the title of “ Ballantrae rocks.” It was perfectly clear however that before the Girvan stratigraphy should be regarded as even fairly complete it would be absolutely necessary to—(1) study in greater detail the rocks of the altered or so-called “ Ballantrae patches” within the limits of the Girvan area, and separate off their included post-Girvan igneous intrusions and the Girvan rocks these had hardened and altered, from the truly older stratiform rocks of pre-Girvan date ; and (2), to establish on the same paleontological evidences as those relied upon in determining the systematic position of the various members of the Girvan succession, the pre-Girvan age of those members of the Ballantrae complex which were held by myself to be of higher antiquity than the basement beds of the (Upper Llandeilo) Girvan succession. 1 Compare Lapworth, Q.J.G.S. 1878, p. 341; zdid. 1882, p. 663; and Trans. Geol. Soc. Glasgow, 1878, p. 83. 2 Lapworth, Q.J.G.S. 1882, vol. xxxviii. p. 663. 22 Prof. C. Lapworth—Ballantrae Rocks of South Scotland. With these especial aims I paid a visit to the Girvan district in 1885, and was then able to satisfy myself upon the following points :— 1. The diabases, syenites, gabbros and serpentines occurring in the altered patches within the limits of the Girvan district proper are many (if not all) of post-Girvan (post-Silurian ?) age. They occasionally traverse, and usually harden and alter, such of the Lower Girvan rocks as they are locally associated with (as at Shallock Hill, Meadow- head, Byne Hill, Laggan Hill, Craighead Hill, and the slopes of the valley of the Stinchar) ; so that (exception being made of some of the strata of the last three areas named) the igneous and altered rocks of these patches have no claim to be ranked as of Ballantrae age. These post-Girvan igneous rocks have intruded themselves mainly in sheets along the many anticlinal arches into which the Girvan rocks are thrown, either between the Girvan rocks and the Ballantrae rocks proper, or among the limestones and conglomerates. etc., which make up the basal members (Barr or Stinchar Series) of the Girvan succession. 2. Similar igneous rocks (apparently of corresponding age) are met with in mass within the limits of the Ballantrae region itself, and have been equally operative in hardening and altering the enveloping strata. But in addition to these post-Girvan masses and the infolded Girvan (Stinchar) limestones and conglomerates of the region already referred to, the Ballantrae rock complex actually includes great thicknesses of stratiform rock—volcanic (contempo- raneous), sedimentary, altered and unaltered; some of the last of which are distinctly of pre-Girvan date (and consequently of higher antiquity than any fossiliferous stratum yet recognized in the Southern Uplands)—for they contain locally a well-marked Graptolitic fauna of Arenig age. The Arenig fossils occur in certain hardened black shales on the sea-shore at Bennane Head, about the centre of the Ballantrae area. These shales are associated with siliceous and felspathic grits and flagstones, purple shales, conglomerates and various igneous and altered rocks. Similar black shales occur near Lendalfoot. on the north-western slopes of Craighead Hill and elsewhere, but hitherto they have afforded no determinable fossils. The recognizable forms collected by myself from the Bennane shales include : Phyllograptus typus, Hall. Didymograptus extensus, Hall. Tetragraptus quadribrachiatus, Hall. ss bifidus, Hall. an bryonoides, Hall. Caryocaris Wrightii, Salter. * Sruticosus, Hall. Associated with forms of Dietyonema, 99 Biysbyi (caduceus) ?, Hall. Lingula and Obolella. It is almost unnecessary perhaps to point out that we have here a Scottish representative of the well-marked fauna of the middle zones of the Arenig Quebec or first Ordovician fauna of South Britain, Northern Europe, and Hastern America. Not only is the general facies of the fauna’ of the well-known Arenig Point Levis, or Skiddaw type, but the Bennane forms occur—as will be apparent from a study of the following table—always in the same association, Prof. C. Lapworth—Ballantrae Rocks of South Scotland. 23 TABLE SHOWING THE RANGE OF THE BALLANTRAE GRAPTOLITHINA. Oy & 8 wa ist -) a Ad S| 3 las|5e8|ho|ao | *, Aa el) cai ea ae alee ; ; SPECIES, Seat eliaeen | sie Ibe. te ae|u=igglee|fe|ss]| 2 s | SO |BC|SE| mal mal] 2 mo os o- ro) <_< = aS | a SS = ale| S)e4i1e |e = e| a < Ay Pa Phyllograptus typus, Hall ... x x x x x x Tetragraptus bryonoides, H. sais Ke x x x xa exe i quadribrachiatus, Hi. 5K at | Xen XS ox x x x 9 fruticosus, Hall peal eta lc x xe x x op Bigsbyi, Hall Dae iaaay 4. 09% x x x Didymograptus extensus H. aa cei aeeemmllieees i, || 25 x x x HA bifidus, H., Murchisoni, Beck.) x | x | x IK pan xx Oaryocaris Wrightii, Salt. .. ane melt x We have therefore in the foregoing facts a complete paleonto- logical demonstration of the theory that the local series of rocks to which the title of Ballantrae Series or ‘“‘ Ballantrae rocks ” has been applied, is in reality a complex of stratified, altered, and igneous rocks of very different geological ages: Arenig, Llandeilo, and post- Ordovician: the common facies of the pseudo-series being mainly the result of the common interfolding, alteration, and intrusion its rocks have undergone. The development of the natural order, inter-relationships and mode of alteration of this complex has yet to be worked out, and can only be satisfactorily accomplished by a mapping of the entire district, zone by zone, and band by band. When that work has been completed, it is by no means un- likely that fossiliferous zones of a yet higher antiquity may be detected; and that here it will be shown that, as elsewhere, the most extreme views held regarding the collective rock series may each have contained a certain proportion of the actual truth. Although the simple fact of this discovery of an Arenig fauna in the Ballantrae rocks has long been made known,® I have hitherto with- held the foregoing details, because of their vital bearing upon the general question of the true sequence of the Lower Paleozoic rocks of the Scottish Uplands. The present, however, appears to be the most natural time for their publication. The epoch-making memoir by Messrs. Peach and Horne on the structure of the N.W. High- lands in the Quarterly Journal of the Geological Society for August, 1888, p. 378, has given the finishing-stroke in Britain to the antiquated ideas of the reliability of apparent stratigraphy in areas subjected 1 Nicholson, 1872, Brit. Mon. Grapt. p. 97, etc. 2 Hopkinson and Lapworth, Q.J.G.S. 1875, p. 635. 3 Hall, Grapt. Quebec, 1865, pp. 56-57. * Coll Canadian Geol. Survey. 5 Tullberg, Skanes Grapt. pt. i. 1882, p. 22, ete. 6 Brégger, Die Silurischen Etagen 2 und 3, 1882, pp. 38-41. 7 Lapworth, Geol. Dist. Rhabdophora, 1879, p. 23. 8 Jukes-Browne, Historical Geology, 1886, p. 98. 24 J. W. Gregory—A new Protaster from Australia. to intense lateral pressure. The conscientious and detailed paper by Messrs. Marr and Nicholson! on the Stockdale Shales of the Lake District, in the November Number of the same publication, has brought home to British geologists, in an equally convincing manner, the untenability of the views of those few surviving stratigraphists who still hesitate to acknowledge the paramount value of the Grap- tolites in the elucidation of complicated questions of stratigraphy and correlation among the Lower Paleozoic rocks. In these two typical papers the zonal and detailed method of stratigraphy, as opposed to the regional and generalized method, has been consistently followed throughout, and it is to the adoption of this method I believe that they owe their reliability and their success. ‘This zonal method, which has always been employed by myself in my work among the convoluted rocks of the Scottish Uplands, has thus quietly entered upon what may be regarded as the accepted or orthodox stage. With the new interest springing up among British geologists respecting the natural sequence and the proper classification of the Lower Paleozoic rocks, it may be regarded as certain that the complicated region of the Scottish Uplands will now be studied in fuller detail by geologists acquainted with the new methods, and that such differences of opinion as still exist among geologists respecting these rocks will soon find their natural solution and harmony, as in the cases of the Lake District and the N.W. Highlands, in a careful and detailed investigation of all the actual facts. (To be concluded.) V.—On a Nuw Species or tou Genus Prorasrer (P. BRISINGOIDES), FROM THE Upper SILURIAN OF VicTroria, AUSTRALIA. By J. Watter Grecory, F.G.S8., F.ZS., of the British Museum (Natural History). S° little is as yet known of the Paleozoic Ophiuroidea, that the ) discovery of some specimens that represent a new species of Protaster in the Upper Silurian rocks of Victoria is of interest. Some of the specimens were forwarded to Dr. Woodward by Mr. Frederick McKnight, of 60, Hawke Street, West, Melbourne, Victoria, some time ago, but they were too fragmentary to be of much service; several better examples having been received from the same source, Dr. Woodward has kindly entrusted them to me for description. Protaster brisingoides, n.sp. Disk obscurely indicated: apparently of medium size and pen- tagonal in shape, each face being concave owing to the disk extend- ing slightly along the arms. It is seen only in one specimen, and in this but faintly. The arms are at least twice as long as the diameter of the disk, and probably considerably more, the full length not being known. The mouth-frames are homologous with the ambulacral ossicles of 1 Quart. Journ. Geol. Soc. (read May 9), 1888, vol. xliv. J. W. Gregory—A new Protaster from Austraha. 25 the arms; they are about three times as long as broad and some- what spindle-shaped, being more bulging in the middle than in F. leptosoma, which is the nearest ally of this species; the margins are entire and not notched as in that species. The adambulacral elements in the “oral pentagons” probably represent the jaw and jaw-plate ; the former is long and narrow, abont four times as long as broad, and slightly curved at the inner end (Fig. 3, b); the jaw-plate, which unites the jaw to that of the adjoining radius, is short and thick ; its inner surface is concave, as the two free corners extend somewhat towards the centre of the disk (Fig. 4, c). Neither buccal nor dental papille nor teeth are shown. Each arm consists of a series of pairs of ambulacral ossicles (Fig. 2, ao) and adambulacral plates (Fig. 2,1) on each side of a median ridge, seen on the abactinal surface (Fig. 2, d): the first apparently represent the unfused halves of the ambulacral or verte- bral ossicles of Ophiuroids; the second, the lateral or adambulacral shields: the nature of the median ridge is doubtful; it may possibly represent upgrowths from the ambulacral ossicles comparable to those in Brisinga, or it may have some connection with the dorsal shields, which are not otherwise indicated. Seen from the abactinal aspect, the ambulacral ossicles appear thick and bluntly oval, with the longer axis in the direction of the arm, and placed alternately im the concavities of the sinuous median ridge; they are distinctly Dima stone: — Diameter ofidisk eeMameee) ls... 0...) Heeninerenel idee tl ascralin nde cons Diameter to the extremities of the oral pentagons ... 7 mm. Width oftarmi ae emibees co, | os spnseay MRee ee Cuerpo une, Length of ambulacral ossicles ... ... ... «. s 1mm. EXPLANATION OF THE FIGURES. Fig. 1, Specimen of Protaster brisingoides, abactinal aspect; nat. size.’ Fig. 2. Part of an arm from the same specimen, that which is uppermost in Fig. 1; d. median ridge; ao ambulacral ossicle, 7. adambulacral plate: x4 diam. Fig. 8. The oral apparatus from another specimen in which the disk is not shown; 4. jaw, c. mouth-frame; x4 diam, Fig. 4. A jaw-plate and distal . ends of a pair of jaws; x8 diam. 1 The faint indication of a disk is not shown in the figure, but can be detected in one or two of the interradil. 26 J. W. Gregory—A new Protaster from Australia. alternate in the arms, but in the disk, which includes the first three pairs, they are merely subalternate. The ambulacral ossicles are much thicker than those of other species of Protaster, and they are consequently less numerous. They are separated by double concave spaces, which served for the passage of the tube feet (or of the ampulle, if, as is not improbable, the tube feet were arranged on the Asteroid type). The adambulacral plates are long and quad- rangular, running parallel to the arms, each slightly longer than the corresponding ambulacral ossicle. The actinal aspect of the arms is not well exposed in any of the Specimens; in one, however, the end faces of the adambulacral plates are seen, as at their aboral extremities they curve actinally. Neither the articular facets of the ambulacral ossicles nor the arm spines are shown. Locality and stratigraphical position—The specimens were found in the so-called ‘‘Mayhill Sandstone” of Moonee Ponds, Flemington, near Melbourne; they are Upper Silurian in age, but there seems no sufficient reason for regarding the beds from which they have been derived as in any way the equivalent of our Mayhill Sandstone. The rock is a yellowish, fine-grained, micaceous sandstone, from which all calcareous matter has been dissolved, so that the fossils occur only as casts and impressions coloured by iron oxide. Affinities of the species.—The only species of Protaster for which this could be mistaken is P. leptosoma, Salter, trom the Leintwardine Flags of Ludlow ; from this, however, it may be readily distinguished by the shape of the mouth-frames and of the ambulacral ossicles. In a list of fossils from the Upper Silurian rocks of Victoria, published by F. M‘Coy in 1874,' the MS. name of Teeniaster australis is recorded from the Upper Yarra. This may refer to the species here described, which at first sight, in specimens that do not show the disk, is not unlike a Zeniaster ; in the absence of any description of M‘Coy’s species, it is quite impossible to say whether such is the case, and as the specimens do not come from the same locality, though some of the Asteroids recorded are from Moonee Ponds, it would not be safe to adopt M‘Coy’s manuscript name. It serves, however, to remind us of the differences of opinion as to the relations of Teniaster and Protaster, which Hall? maintained were very closely allied, if not identical, attributing the supposed differ- ences between them to errors in description by Salter.® According to the original description by Billings,‘ Toeniaster differed from Protaster in the absence of a disk, in the development of the oral plates from the adambulacral plates and not from the ambulacral elements, and in that the pores pass through the spaces between the ' R. B. Smyth, Progress Reports, Geol. Survey, Victoria, No. 1, Melbourne, 1874, p. 34. 2 a) Hal 20th Regents Report, Albany, 1867, pp. 298-4 and 300-1. 3 J. W. Salter, On some new Paleozoic Starfishes, Ann. and Mag. Nat. Hist. ser. 2, vol. xx. 1857, pp. 330-2, pl. ix. figs.4 and 5; and Additiunal Notes on some new Palzozoic Starfishes, ser. 8, vol. viii. 1861, pp. 484-6, pl. xviii. figs. 9, 10, and 11. 4 Ii. Billings, On the Asteriade of the Lower Silurian Rocks of Canada, Canadian Org. Remains, dec. iii, Montreal, 1858, p. 80-1, pl. x. figs. 8 and 4. Dr. R. H. Traquair—On Tristychius and Ptychacanthus. 27 ambulacral ossicles and the two adjoining adambulacral plates, and not through the body of the ambulacral ossicle itself. Hall has claimed to have discovered traces of a disc in Billings’s type specimens of Teeniaster, and if so, this distinction falls to the ground ; but, in regard to the two other points, the collection of specimens of P. Miltoni in the British Museum Collection confirm the correctness of Salter’s views. The differences are, therefore, valid ones, and both genera must be retained, as has been done by Zittel. This new species differs from Teniaster in the presence of the disk, though, as we have seen, this distinction may possibly not hold good, and in the structure of both arms and oral pentagon. It undoubtedly differs from the other species of Protaster in many important points of structure, and herein agrees more closely with Brisinga than does any Prot- ophiuroid yet described; to mark this resemblance the specific name has been given. But the other species of Protaster differ among themselves in equally important points, and the genus is apparently constituted by a group of species which careful revision and further knowledge of their structure would probably relegate to more than two distinct genera. The necessity for such a revision has been recently urged by Sturtz,! and to this with a discussion of some questions in their anatomy and the significance of some points in the structure of P. brisingoides, I hope subsequently to return. Till such has been done, it seems advisable to include this species in the comprehensive genus Protaster. VI.—Nore on THE Genera TRisTYcHius AND PTYCHACANTHUS, AGASSIZ. By Dr. R. H. Traquatr, F.R.S., F.G.S. Se years ago,?in showing that the spines supposed by Hancock and Atthey to be dorsal spines of Gyracanthns were merely young and unworn specimens of lateral spines of the same genus, T called attention to the general fact that young examples of Selachian spines could not be expected to represent the older ones in miniature, and vice versa. For as the spine increases in size by growth at the base, the young one is consequently represented only by the distal portion of the adult. And as in the process of growth, differences in sculpture and proportions may supervene, the general characters may be so altered, that if the distal portion be lost by attrition, the old and young individuals may be with difficulty recognizable even as belonging to the same genus. Such an instance may, I think, be found in the spines named by Agassiz respectively Tristychius arcuatus and Ptychacanthus sublevis, both from the Lower Carboniferous rocks of Central Scotland. | In very young specimens of the former the surface of the exserted portion is entirely covered with longitudinal ridges and sulci, and 1B, Sturtz, Beitrag zur Kenntniss paleozoischer Seesterne, Palaeontographica, vol. xxxil. Stuttgart, 1886, p. 79. 2 Ann. and Mag. Nat. Hist. ser. 5, vol. xiii. 1884, p. 37. 28 Notices of Memoirs—Rer. G. F. Whidborne—Devonian Fossils. there is scarcely any posterior area, the two rows of marginal denticles being placed close to each other and alternating. As the spine increases in length, the ridges begin to drop off behind, so that in examples of from three to four inches in length, like Agassiz’s type,’ only the tip is ridged all round, while three ridges, one median and two lateral, persist beyond the other along the front, whence the name Tristychius. Along with this change in sculpture, the two posterior rows of denticles diverge from each other, and a well- marked area is formed between them as in Cienacanthus. In still larger spines the sulcated tips become entirely worn off, leaving only the three anterior ridges, which in turn also finally disappear in examples which have been subjected to any consider- able amount of wearing. A somewhat short, gently-curved, bluntly- pointed spine now contronts us, destitute of ridges or sulci, and with the surface covered only by very close and delicate striz. Such spines are indistinguishable from Agassiz’s description and figure of Piychacanthus sublevis,? of which the original seems unfortunately to be lost, for although Agassiz states that it belonged to Professor Jameson, I have never been able to find it in the Edinburgh Museum. Ptychacanthus sublevis then represents to my mind nothing but an adult Tristychius arcuatus, with the point broken off, and the general surface a little worn, and this view is, I consider, not only corroborated, but proved by a series of specimens of undoubted Tristychius in the Edinburgh Museum. INj@ i EC Swern Vir VE@ dees: ].—AMeBLyYprisTIs CHOPS, NOV. GEN. ET. SP., AUS DEM HocAEN Axneyprens. By Prof. Dr. W. Dames. Sitzungsb. Ges. naturf. Fr. Berlin, 1888, No. 6. HIS paper forms an interesting contribution to our knowledge of the fossil vertebrate fauna of Birket-el-Qurin, in Fajum, for which we are already indebted to Dr. Dames (Sitzungsb. konigl. Akad. Wiss. Berlin, 18838, pt. i.). The evidence of the new Saw-fish (Amblypristis Cheops) consistsin some detached rostral teeth, differing from those of the existing Pristisin their shortness and great relative breadth. One example is figured; and Dr. Hilgendorf adds a brief note on the structure of the rostral teeth of the living genus, as compared with the fossil. I].—Own some Devontan Crustacea. By Rev. G. F. Warpsorne, M.A., F.G.S.3 ESIDE species of Crustaceans already described from Woul- borough and Lummaton, several new species are found there, as the following : Phacops batracheus, which differs from P. fecundus, Barr., in the rearward position of the eye and more overhanging glabella; Proetus batillus, which has a flatter glabella than P. 1 Poiss. Foss, tome iii. tab. 1a, fig. 9-11, ? Op. cit. tome iii, tab. 5, fig. 1-3. 3 Revised abstract of paper read at the British Association. Notices of Memoirs—Rev. G. F. Whidborne—Devonian Fossils. 29 bohemicus, Barr., more anterior eyes, and longer cheek spines; P. subfrontalis, which approaches P. frontalis, Barr., but has a much squarer glabella; P. audax, which is like P. granulosus, Goldf., but has tuberculated cheeks; Cyphaspis ocellata, like OC. ceratophthalmus, Sandb., but with long sharp cheek spines ; Lichas devonianus, having a wider head than ZL. Haveri, Barr., larger eyes surrounded by tubercles, and a more arched neck; Acidaspis Robertsii, with narrower cheeks than 4. lacerata, Barr.; A. Hughesti, with a bilobed tail surrounded by a flat border bearing aciculate spines; Bronteus delicatus, having its glabella marked with transverse lines, and smaller spots than in B. flabellifer, Goldf.; B. pardalios, which is more coarsely tuberculated than B. granulatus, Goldf.; Entomis peregrina, distinguishable from H. tuberosa, Jones, by the indistinct- ness of its nodule; and Bactropus decoratus, dissimilar from B. longipes, Barr., in being much smaller and more coarsely striated. The Cheirurus of these beds is not Ch. articulatus, Minst., but a new species, C. Pengellii, differing from it in the shorter front lobe of its glabella. The true B. flabellifer, Goldf., occurs, not at Woul- borough, but at Chircombe Bridge, where it is accompanied by Dechenella setosa, u.sp., differing from D. Verneuili, Barr., in having nineteen segments on the tail. TII.—On some Drvontan CErpHALOpopS AND GasTEROPODS. By Rev. G. F. Waipsorne, M.A., F.G.S. HE following new species occur at Woulborough or Lummaton, or in the case of some of the Gasteropods at Chudleigh: Goniatites obliquus, a large shell with open umbilicus, flat sloping sides and narrow flat back; G. psittacinus, a small tumid shell with closed umbilicus, rounded whorls, slightly curved sutures; G. nuci- formis, with minute umbilicus and much broader back than the preceding; G. aratus, a flatter shell with small umbilicus, and marked with four angulated sulci; G. pentangularis, with open spire, inner whorls ribbed, and section of whorls pentagonal; G. Hughesii, large and flat with closed umbilicus, evenly rounded back and minutely striated surface; Cyrtoceras Leei, a large curved conoidal form with more irregular and dilate lamelle than C. fimbriatum, Ph. ; C. pulcherrimum, unlike C. reticulatum, Ph., in having tubercles on the shoulder instead of ribs; C. Vicarii, having a broader section, and much fewer tubercles than the last ; C. preclarum, more involute and elliptical than the last, with wider mouth and oblique ridges crossed by distant striae; C. majesticum, large and smooth, with oval mouth, narrow chambers and imperfect spire; Hercoceras inornatum, differing from H. subtuberculatum, Sandb., in being smooth ; Ortho- ceras hastatum, more conical and with fewer annule than O. tubi- einella, Ph.; O. Vicarti, differing from O. pulchellun, F. A. Rom., in being round and not oval in section; O. comatum, which is O. tubicinella, Sandb., not Ph.; Phragmoceras vasiforme, which is rather less convex than Ph. subpyriforme, Mu.; Ph. ungulatum, small and more arched than C. cornucopia, Sandb. ; Ph. Marri, conical and transversely flattened, approaching G. Conradi, Barr.; B. mundus, 30 Notices of Memoirs—Lapworth’s N. American Graptolites. with broad grooved keel, and very transverse kidney-shaped mouth ; Euomphalus fenestralis, with a depressed spire and three ridges cancel- lated by numerous rings; Pleurotomaria perversa, a large sinistral shell, unlike Pl. expansa, Ph., in having spiral striz, a deeper suture, whorls more convex; P/. victriz, which has an elevated spire, angu- lated whorls, central sinus band, and a few spiral strie; Pl. Chud- leighensis, separated from the preceding in having its spiral ridges crenulated, and the sinus band much higher; Littorina devonaic, having the general shape of Purpura lapillus, with eight spiral rows of tubercles which are largest near the suture; Monodonta archon, very large and trochiform, with flat base and sides, linear suture and oblique growth-lines; Phorus philosophus, with a low spire, wide umbilicus and convex whorls bearing fragments of broken shells ; Macrocheilus tumescens, a much more globular form than M. sub- costatus, Schlot.; Turbo Pengellii, unlike T. subangulosus, dA. and de V., in its wider flatness above the shoulder; Loxonema scala- roides, very elongate, with its convex whorls crossed by discontinuous varices ; H. duplisulcata, differing from H. tenuisulcata in possessing a series of subsidiary striz; Acroculia columbina, a wide depressed form with fine waving longitudinal markings; Metoptoma cordata, like M. pileus, Ph., but with loftier umbo and more angulated mouth; and Chiton papilio, which comes midway between Ch. corrugatus, Sandb., and Ch. sagittalis, Sandb. The above are accompanied by Orthoceras Oceani, d’Orb. (= O. cinctum, Ph.), O. tenuistriaius, Miui., O. subfusiforme, d’A. and de V., O. regularis, Mi... O. subarmularis, Mi., B. lineatus, Goldf. (= B. striatus, Ph.), P. bifida, Sandb. (=B. Woodwardii, Ph.), Hu. serpula, de Kon., Lu. planorbis, d’A. and de V., Hu. levis, d’A. and de V., Hu. rota, Sandb., Hu. decussatus, Sandb., Hu. germanus, Ph. sp., Eu. cate- nulatus (=EHu. serpens, Ph., Pal. Foss. fig. 172, f. and g. only), PI. D’ Orbigniana, @A. and de V., Pl. subclathrata, Sandb., Pl. Lonsdalit, d’A. and de V., Pl. delphinuloides, Schlot., Pl. calculiformis, Sandb., Pl. trochoides (=Pl. monilifera, Ph. Pal. Foss.), Pl. distinguenda (=PI. aspera, Ph. Pal. Foss.), N. deformis, Sow., N. piligera, Sandb., T. multispira, Sandb.? Z. purpura, dA. and de V., L. subcostata, d’A. and de V., Scalaria antiqua, Mii., M. subcostatus, Schlot. (=. arculatus, Ph., and M. elongatus, Ph.), Scoliostoma tewatum, Ph. sp., Sc. gracile, Sandb., Holopella tenuicostata, Sandb., H. tenuisuleata, Sandb., 4. piligera, Sandb., Acroculia multiplicata, Giebel, and A. progeva, Hichw. IV.—Nore on Grapronites From Drase River, B.C.' By Prof. Cuarues Lapworth, LL.D., F.R.S., F.G.S. N June, 1887, a small collection of Graptolites was obtained by Dr. G. M. Dawson on Dease River, in the extreme northern and inland portion of British Columbia, about lat. 59° 45’, long. 129°. These fossils were derived from certain dark-coloured, carbonaceous and often calcareous shales, which in association with quartzites and 1 Reprinted from the ‘‘ Canadian Record of Science.”’ Notices of Memoirs—Lapworth’s N. American Graptolites. 31 other rocks, characterize a considerable area on the lower part of the Dease, as well as on the Lizard River, above the confluence. The collection referred to was transmitted by Mr. J. F. Whiteaves to Prof. Lapworth, whose special studies on Graptolites are well known. It is believed that the following preliminary note by Prof. Lapworth will be of interest, as the occurrence of Graptolites on the Dease River extends very far to the north-westward of our previous knowledge of the occurrence of these forms in North America. In 1886 a similar small collection was obtained by Mr. BR. G. McConnell near the line of the Canadian Pacific Railway, in the Kicking Horse (Wapta) Pass. This and the new locality here described are the only ones which have yet been found to yield Graptolites in the entire western portion of the Dominion. Prof. Lapworth, under date December 13th, writes as follows :— I have, to-day, gone over the specimens of Graptolites, collected by Dr. Dawson, from the rocks of the Dease River, British Columbia. I find that they are identical with those examined by me from the rocks of the Kicking Horse Pass, some time last year. The species I notice in the Dease River collection are: Diplograptus euglyphus, Lapworth. Glossograptus ciliatus, Emmons. Climacograptus comp. antiquus, Lapw. Didymograptus comp. sagittarius, Hall. Cryptograptus tricornis, Carruthers. New form allied to Cenograptus. These Graptolite-bearing rocks are clearly of about Middle Ordovician age. They contain forms I would refer to the second or Black River Trenton period: i.e. they are newer than the Point Lévis series, and older than the Hudson and Utica groups. The association of forms is such as we find in Britain and Western Kurope, in the passage-beds between the Llandeilo and Caradoc Limestones. The rocks in Canada and New’ York, with which these Dease River beds may be best compared, are the Marsouin beds of the St. Lawrence Valley, and the Norman’s Kill beds of New York. The Dease River beds may perhaps be a little older than these. Mr. C. White described some Graptolites from beds in the mountain region of the West, several years ago, which may belong to the same horizon as the Dease River zones, though they have a somewhat more recent aspect. The specific identification of the Dease River fossils, I regard as provisional. While the species correspond broadly with those found in their eastern equivalents, they have certain peculiarities which may, after further study, or on the discovery of better and more perfect specimens, lead to their separation as distinct species or varieties. It is exceedingly interesting to find Graptolites in a region so far removed from the Atlantic basin, and also to note that the typical association of Llandeilo-Bala genera and species is still retained practically unmodified.—G. M. D. 32 Reviews—Dr. Geikie—Tertiary Volcanic Action. O59 JE se a A I.—Tur History or Voxucantc ACTION DURING THE TERTIARY Prriop 1n THE BritisH Istus. By ArcHiBaLD Gerrxiz, LL.D., F.R.S., Director-General of the Geological Survey of the United Kingdom. (Transactions of the Royal Society of Edinburgh, vol. xxxv. 1888, pp. 21-184, with 2 Maps and 53 Woodcuts. Reprinted, 4to. Edinburgh, R. Grant & Son. Price 18s.) \HE work before us, probably the most important of the original papers by the author, must be read by every one devoted to the special study of volcanic action ; at the same time it contains results of such high interest to all geologists, that in due course it will doubtless be regarded as one of the ‘ classic’ memoirs of this prolific age. ae the outset the author gives a brief sketch of the labours of previous observers. Foremost among these was Macculloch, and of his great work on the Western Islands of Scotland, Dr. Geikie says, «Few single works of descriptive geology have ever done so much to advance the progress of the science in this country.” It is pleasant to see the labours of the pioneers so fully acknowledged, and in reference to Ami Boué, who published in 1820 his Essai géologique sur l’ Ecosse, it is remarked that “the value of this work as an original contribution to the geology of the British Isles has probably never been adequately acknowledged.” From time to time during the past 30 years Dr. Geikie has pub- lished the results of his own observations on the volcanic rocks of Scotland, but it was not until 1879 that he ‘‘ appreciated for the first time the significance of Richthofen’s views regarding ‘massive’ or ‘fissure-eruptions,’ as contradistinguished from those of central volcanoes like Etna or Vesuvius;” then, however, when traversing some portions of the volcanic region of Wyoming, Montana, and Utah, he “saw how completely the structure and history of these tracts of Western America explain those of the basalt-plateaux of Britain.” In the mean time an elaborate Memoir by Prof. Judd on the Ancient Volcanoes of the Highlands was read before the Geological Society of London; and it is important to notice that the conclusions of Dr. Geikie are to a very large extent at variance with those of Prof. Judd. The latter had recognized the basal wrecks of five great central volcanoes in the Western Islands; whereas Dr. Geikie has not been able to discover evidence of any great central volcanoes, and has found the order of outflow of the successive groups of rocks to have been the reverse of what Prof. Judd believed it to be. In the present memoir Dr. Geikie commences his history of volcanic action with an account of the basic dykes, which traverse so large a part of Scotland, and extend also into the North of Ireland, the Isle of Man, and the North of England. Of these dykes, that in Cleveland is one of the best-known English examples. The author then describes the great volcanic plateaux, which, in spite of vast denudation, still survive in extensive fragments in Antrim and Reviews—Dr. Geikie—Tertiary Volcanic Action. 33° the Inner Hebrides. The eruptive bosses of basic rocks that have broken through the plateaux are next discussed, and then an account is given of the protrusions of acid rocks that mark the latest phase of eruption in the region. Finally, the leading features in the history of Tertiary volcanic action in the British Isles are summarized by Dr. Geikie, whose words we quote as far as possible in our condensed account of his views. The earliest beginnings of the volcanic disturbances may possibly go back into the Eocene period, and the final manifestations may not have ceased until Miocene times, or perhaps later. . These disturbances originated from a vast subterranean lake or sea of molten rock, which appeared beneath the volcanic region as it underwent elevation. Enormous horizontal tension arose, and a system of approximately parallel fissures opened in the terrestrial crust, having a general direction towards N.W. The majority of the fractures did not reach to the surface of the ground, though probably not a few did so. No sooner were the fissures formed than the molten lava underneath was forced upward into them for many hundred or even thousands of feet above the surface of the sub- terranean lava-sea. Solidifying between the fissure-walls, the lava formed the numerous basic dykes that constitute the widespread and distinctive feature of the volcanic region. Where the fissures reached the surface or near to it, the molten rock sought relief by egress in streams of lava, of which abundant remains are still left in the basalt- plateaux of Antrim and the Inner Hebrides. In some places, the accumulated pile of such ejections, which include layers of fine tuff, etc., even now exceeds 3000 feet. The surface over which the lava flowed seemed to have been mainly terrestrial, for here and there, between the successive sheets of basalt, the remains of land-plants and also of insects have been discovered. Subsequently there uprose at certain points, coarsely crystalline basic rocks, which solidified as dolerites, gabbros, etc. Probably long after the eruption of the gabbros, a renewed out- break of subterranean activity gave rise to the protrusion of rocks of a markedly acid type. They include varieties that range from felsites through porphyries and granophyres into granite. Around the bosses of gabbro and granophyre, the bedded basalts have undergone considerable contact-metamorphism ; and it is inte- resting to learn that the former precisely resemble rocks of similar kinds in Paleozoic and Archean formations. Ultimately another system of basic dykes was formed; dykes which cross those of earlier date, and rise through the other volcanic rocks. We have passed over the more detailed portions of this work, contenting ourselves with pointing out the leading conclusions of the author. These are indeed based on extensive microscopic in- vestigations of the rocks, as well as on the more important field- work. Further particulars, however, of the microscopic petrography are promised in a future memoir on the subject, by Dr. F. H. Hatch, whose assistance is cordially acknowledged by the author. DECADE III.—VOL. VI.—NO. I. 3 04 Reviews—C. D. Sherborne’s Bibliography of the Foraminifera. - II.—A BrerioGRAPHY OF THE FORAMINIFERA, RECENT AND FossiL, From 1565 to 1888. By C. D. Suerporny, F.G.8. 8vo. pp. vi. and 152. (London, Dulau & Co., 1888.) N the July Number, 1887, of the Grou. Mae. at p. 324, we briefly criticized a “Bibliography of the Foraminifera,” by Prof. Anthony Woodward; and we regretted to point out some of its errors and shortcomings. We can now congratulate Rhizopodists on the publication of a good catalogue of all the books and memoirs treating of Foraminifera that have appeared during more than the last three centuries. The little shelled Protozoans under notice, always either quaint or elegant in form, and offering an interminable series of varied shapes to the microscopist, and highly interesting subjects of research to the biologist, have been treated of in hundreds of works with more or less exactness, and illustrated by thousands of plates of very different values. The bibliographies hitherto given to the public, within the last forty years, have been more or less useful as clues in the finding of some desiderata; but have often disappointed the student, or left him vaguely conscious that more or better work had been done in his line of research. If really desirous of learning what others have worked out, and of comparing the results of those who have preceded him, he now has good aid in his search, and has no excuse should he ignore earlier workers. Having entered on the study of Foraminifera, and finding it necessary to master their bibliographic history, in making tables and catalogues of the multitudinous genera and species already re- corded, Mr. C. D. Sherborn evidently found existing bibliographies too imperfect for the purpose, and therefore consolidated and aug- mented the several lists, which books and friends supplied, as fully explained in his Preface. The result is this excellent Bibliography before us, which has been earnestly and conscientiously carried out, with scrupulous exactness as to dates and titles of books and memoirs, the places of publication, the life-dates of the authors (when obtainable), and a definite uniformity in quoting periodicals and transactions, which especially is as valuable as it is rare. The frequent notes relative to some rare and other publications are of great value: and the enumeration of, or remarks on, the illustra- tions seem to intimate that the author of this “ Bibliography ” could supply an index of genera and species, very many of which are notoriously synonymous, having been determined and published without due regard to previous publications. Mr. Sherborn has adopted the plan of enumerating the authors (about 700) in alphabetical order, and the works of each in order of date (about 2000), with cross-references. Of the books and papers thus mentioned only about 20 are noted as not having been seen, with such care and exactness has the work been carried out. There is a very short list of errata in the book, and scarcely any others can be found even after a considerable use of this valuable Bibliography. Strata of various ages have yielded so many Foraminifera that the geological formations are frequently mentioned in connection with them in the titles and pages of the books and memoirs here enumerated ; Reports and Proceedings—Geological Society of London. 30 hence the Geologist, as well as the Biologist, has an interest in this Bibliography, which we cordially recommend to both as highly necessary in their researches. IIJ.—Tasurar Inpex to THe Upper Cretaceous Fossits or Enc- LAND AND IRELAND, cited by Dr. Charles Barrois in his “ De- scription Géologique de la Craie de Ile de Wight,” Paris, 1875, and “ Recherches sur le Terrain Crétacé Supérieur de Angleterre et de l’Irlande,” Lille, 1876. By E. Wustiaxs, F.G.S. 4to. pp. 24 (Fordingbridge, Mitchell, 1888.) HIS tabular list gives the geological distribution in the different zones of the Cenomanian, T'uronian and Senonian divisions, of 405 species of Cretaceous fossils, referred to in the above-named works of Dr. Barrois; and also references to the localities where they occur. It appears to have been very carefully compiled, and should prove of very material assistance to all workers in the Cretaceous rocks of this and other countries. ee @ ee ae SS) ASN) Ee @ C saa INES ————= > GroLoGIcAL Society oF Lonpon. I.— November 7, 1888.—W. T. Blanford, LL.D., F.R.S8., President, in the Chair.—The following communications were read :— 1. ‘The Permian Rocks of the Leicestershire Coal-field.” By Horace T. Brown, Esq., F.G.S. The author considers that whilst rocks belonging to the Car- boniferous and Trias have been mapped as Permian, true represen- tatives of the Permian do exist in the district to a considerable extent. The Bunter conglomerates rest for the most part upon the truncated edges of Carboniferous strata; but intercalated between them and the Carboniferous, at various points, are thin beds of purple marly breccias and sandstones seldom exceeding from 30 to 40 ft., but differing in lithological character from the overlying and underlying rocks. The brecciated series rests with striking unconformity upon the Carboniferous. Moreover, the Boothorpe fault, which throws the Coal-measures 1000 ft., affects the over- lying brecciated series to an extent of not more than from 20 to 30 ft. The unconformity between the brecciated series and the Bunter is less obvious. Sections establishing the double uncon- formity were described in considerable detail. Attention was also called to other localities within the Coal-field where Permian rocks exist, the author having in many cases mapped their boundaries. He further called attention to certain beds which have been erroneously classed as Permian by the Survey. The first of these is a patch at Knowle Hills. Making extensive use of the hand- borer, he found that the greater part of the so-called Permian consists of a wedge-shaped piece of Lower Keuper let down by a trough fault. The so-called Moira grits belong to and are con- formable with the ordinary Coal-measures of the district. 36 Reports and Proceedings— The lithological characters of the Leicestershire Permians is sufficient to differentiate them from the Trias and Carboniferous. They consist of red and variegated marls, bands of breccia, and beds of fine-grained yellowish sandstone; the breccia fragments are of great variety and little waterworn. These are imbedded in a bluish-grey matrix, hard or soft, which consists of insoluble matter united by the carbonates of lime and magnesia with some hydrated ferrous oxide, which on exposure becomes oxidized. The breccias have a tendency to die out northwards. The most abundant materials are quartzo-felspathic grits with associated grey flinty slates (Older Palaeozoic), with in addition vein-quartz, voleanic ash, and igneous rocks. The Carboniferous rocks afford argillaceous limestone, Mountain Limestone, grits, and hematite. At Boothorpe nearly 90 per cent. is made up of the old Palzozoic material, whilst at Newhall Park 28-8 per cent. consists of Carboniferous grits and hematite. The quartzite fragments resemble those of the lower part of the Hartshill series, but the existence of “ strain shadows ”’ indicates a difference subsequently explained. A very few frag- ments may be referred to the Charnwood rocks. The bulk of the material has a southern origin, and the irregu- larity of the fragments proves that they cannot have come from a distance. Evidence is given of the probable existence of a ridge of older Paleozoics, from which the Carboniferous rocks had been stripped, beneath the Trias of Bosworth. (There is an actual outcrop of Stockingford shales at Elmesthorpe.) The direction of this line is parallel with the Nuneaton-Hartshill and Charnwood axes of elevation, and also with the general direction of the major folds and faults of the Leicestershire Coal-field. The northern part of this ridge, which is apparently a faulted anticlinal, is a very probable source of the angular fragments occurring in the Permian breccias 5 or 6 miles to the north-west. The author concluded that the Permian rocks of the Leicestershire Coal-field belong to the same area of deposition as those of War- wickshire and South Staffordshire, all having formed part of the detrital deposits of the Permian Lake which extended northwards from Warwickshire and Worcestershire, and which had the Pennine chain on its eastern margin. He pointed out the dissimilar nature of these deposits to those of the eastern side of the Pennine chain from Nottingham to the coast of Durham. There were proofs of the existence of a land barrier, owing to the uprising of the Carboniferous, between the district round Nottingham and the Leicestershire Coal- field. The most northerly exposure of the Leicestershire Permians is 13 miles 8.W. of those of South Notts. He indicated the probable course of the old coast-line of the western Permian Lake. Denudation had bared some of the older Paleeozoics of their overlying Coal- measures, and it is the rearranged talus from the harder portions of these older rocks which now form the brecciated bands in the Leicestershire Permian. In an Appendix some igneous rocks found in the Bosworth borings were described. Geological Society of London. 37 2. “On'the Superficial Geology of the Central Plateau of North- western Canada.” By J. B. Tyrrell, Hsq., B.A., F.G.S., Field Geologist of the Geological and Natural History Survey of Canada. The Drift-covered prairie extends from the west side of the Lake of the Woods to the region at the foot of the Rocky Mountains, rising from a height of 800 feet on the east to 4500 feet on the west, the gentle slope being broken by two sharp inclines known as the Pembina Escarpment and the Missouri Coteau, giving rise to the First, Second, and Third Prairie Steppes. The author described the older rocks of this region, referring especially to his subdivision of the Laramie Formation into an Edmonton Series of Cretaceous age, and a Pascapoo Series forming _ the base of the Eocene, and then discussed the Superficial Deposits in the following order :-— 1. Preglacial gravels occurring along the foot of the Rocky Mountains, composed of waterworn quartzite pebbles, similar to those now forming and, like them, produced by streams flowing from the mountains. 2. Boulder-clay or Till, having an average thickness of 50-100 feet, and filling up pre-existing inequalities. The clay is essentially derived from the material of the underlying rocks. The smoothed and striated boulders of the western region are largely quartzites derived from the Rocky Mountains; these gradually disappear towards the east, and are replaced by gneisses and other rocks transported from the east and north-west. Towards the north-west several driftless hills over 4000: feet high appear to have stood as islands above the sheet of ice. Some of the surface erratics of gneissose rock have doubtless been derived from the Till, whilst others are connected with moraine deposits, and others, again, appear to have been dropped from bergs floating in seas along the ice-front. The Till is sometimes divisible into a lower massive and upper rather stratified deposit, separated occasionally by 3. Interglacial Deposits of stratified material, with seams of im- pure lignite, and shells of Pisidium, Limnea, Planorbis, etc. 4. Moraines, which are intimately associated with the Boulder-clay, and represent terminal moraines of ancient glaciers which originated upon or crossed the Archean belt. One of these is the well-known Missouri Coteau. After pointing out the derivation of quartzite pebbles in the drifts of the eastern region from Miocene conglomerates, and not directly from the Rocky Mountains, the author described 5. The Kames or Asars generally occurring at the bottoms of wide valleys, and which resemble in structure those of Scandinavia. 6. Stratified Deposits and Beach-ridges which have been formed at the bottoms and along the margins of freshwater-lakes lying along the foot of the ice-sheet. The principal of these occupied the valley of the Red River, and has been called Lake Agassiz ; it had a length of 600 miles and a width of 170 miles. The author described in detail the gravel terraces formed around this lake, and showed that a slow elevation had taken place towards the north and east 38 | Reports and Proceedings— since their formation. He favoured the view that the waters of the lake were dammed by the ice towards the north. An account was given of some quartzite flakes, apparently chipped by human agency, in one of the terraces of this lake. On the recession of the ice the southern drainage-channel was abandoned, and a northerly one opened out. 7. Old Drainage-channels.—Throughout the whole region old drain- age-channels appear to have been occupied by southerly running rivers (where the present drainage is northerly), and are considered to have carried away the waters draining from the foot of the ice. Some of these valleys have been blocked by moraines in the Duck Mountains, the result of local glaciers. II.—November, 21, 1888.—W. T. Blanford, LL.D., F.R.8., Presi- dent, in the Chair. W. Whitaker, Esq., B.A., F.R.S., F.G.8., who exhibited a series of specimens from the deep boring at Streatham, made some remarks upon the results obtained, of which the following is an abstract :— After passing through 10 feet of gravel, etc., 153 of London Clay, 884 of Lower London Tertiaries, 623 of Chalk (the least thickness in any of the deep borings in and near London), 283 of Upper Greensand, and 1884 of Gault, at the depth of 10814 feet hard limestone, mostly with rather large oolitic grains, was met with. This, with alternations of a finer character, sandy and clayey, lasted for only 883 feet, being much less than the thickness of the Jurassic beds, either at Richmond or at Meux’s Boring. The general character of the cores showed a likeness to the Forest Marble, and the occurrence of Ostrea acuminata agreed therewith. At the depth of 1120 feet the tools entered a set of beds of much the same character as those that had been found beneath Jurassic beds at Richmond, and beneath Gault at Kentish Town and at Crossness. The softerand more clayey components were not brought up; the harder consist of fine-grained compact sandstones, greenish- grey, sometimes with purplish mottlings or bandings, and here and there wholly of a dull reddish tint. With these there occur hard, clayey, and somewhat sandy beds, which are not calcareous, whilst most of the sandstones are. Thin veins of calcite are sometimes to be seen, and at others small concretionary calcareous nodules ; but no trace of a fossil has been found. The bedding is shown, both by the bands of colour, and by the tendency of the stone to fracture, to vary generally trom about 20° to 80°, In the absence of evidence it is hard to say what these beds are, and the possibilities of their age seem to range from ‘Trias to De- vonian. It is to be hoped that this question may be solved, as on it depends that of the possibility of the presence of Coal-measures in the district ; and Messrs. Docwra, the contractors of the works, have with great liberality undertaken to continue the boring operations at their own expense for at least another week. Details of the section will be given in a forthcoming Geological Geological Society of London. 39 Survey Memoir, in which, moreover, the subject of the old rocks under London will be treated somewhat fully. The following communications were read :— 1. ‘Notes on the Remains and Affinities of five Genera of Meso- zoic Reptiles.” By R. Lydekker, Esq., B.A., F.G.S. This paper was divided into five sections. In the first the author described the dorsal vertebra of a small Dinosaur from the Cambridge Greensand, which he regarded as probably identical with the genus Syngonosaurus, Seeley. Reasons were then given for regarding this form as being a member of the Scelidosauride, stress being laid on the absence of a costal facet on the centrum. The second section described an axis vertebra from the Wealden of the Isle of Wight, which is evidently Dinosaurian, and may possibly belong to Megalosaurus. It is remarkable for exhibiting an inter- centrum on its anterior aspect, and also for the absence of anchylosis between its centrum and that of the atlas. In the third section the femur of a small Iguanodont from the Oxford Clay, in the possession of A. R. Leeds, Esq., was described. This specimen agrees with Hypsilophodon and Camptosaurus in its pendent inner trochanter, and it was referred to the latter genus as C. Leedsi. It is also considered to be closely allied to Iguanodon Prestwichi—the type of Cumnoria of Seeley —which is also considered to belong to the American genus. The name Camptosaurus valdensis was applied to an allied form from the Wealden; and the name Cryptodraco proposed to replace Cryptosaurus. The imperfect skeleton of a Sauropterygian from the Oxford Clay near Bedford, which formed the subject of a previous communication, was redescribed. This specimen was identified with Plesiosaurus philarchus, Seeley, which it was proposed to refer to a new genus under the name of Peloneustus. This genus was shown to be allied to Pliosaurus, and to be represented by forms in the Kimmeridge Clay which have been described as Plesiosaurus equalis and P. ste- nodirus. It was also compared with the genus Thaumatosaurus, Meyer, from which Rhomaleosaurus of Seeley was considered in- separable. Some remarks are added on other Sauropterygians; and it was proposed to adopt the name Cimoliosaurus for all the forms having a pectoral girdle of the type described under the names of Elasmosaurus and Colymbosaurus, and with single costal facets to the cervical vertebra. The paper concluded with a notice of the affinities of the Croco- dilian genus Geosaurus. This form was shown to be closely allied to Metriorhynchus, both being characterized by the absence of dermal ~ scutes and the presence of bony plates in the sclerotic. It was also shown that some of the species of Cricosaurus belong to the former genus; while there appear to be no grounds by which Dacosaurus (Plesiosuchus) can be separated from the same. 2. “Notes on the Radiolaria of the London Clay.” By W. H. Shrubsole, Esq., F.G.S. Microscopical examination of the London Clay of Sheppey and elsewhere has afforded proof of the existence of a Diatomaceous zone 40 . Reports and Proceedings— near the base of the formation. The formation of a well for the Queenborough Cement Company in 1885 was the means of furnish- ing a laminated clay with glittering patches of Diatoms from a depth of 225 feet. In this were also found fairly good pyritized specimens of Radiolaria, some of which were submitted to Prof. Ernst Hackel, who found a large number of fragments of Tertiary Radiolaria, but few well-preserved specimens appertaining to the families Sphe- roidea, Discoidea, and Cyrtoidea, and apparently identical with those described from the Tertiary Tripoli beds of Grotte. No new species occurred among the recognized forms. Sketches made by Mr. A. L. Hammond were also submitted to Prof. Hackel, who stated that these forms were not identical with any known species, recent or fossil. The author described the following new species :—Oornutella Hammondi, Spongodiscus asper, and Monosphera toliapica. — The specimens were preserved in iron-pyrites. Some Tetractinellid sponge-spicules from the washings were recognized by Prof. Sollas. 3. “ Description of a New Species of Clupea (C. vectensis) from Oligocene Strata in the Isle of Wight.” By E. T. Newton, Hsq., F.G.S. : A number of small fishes found by Mr. G. W. Colenutt, of Ryde, during his investigations of the Oligocene strata of the Isle of Wight, in beds belonging to the “Osborne Series,” were described as be- longing to a new species of Clupea. The specimens vary in length from 20 to nearly 60 millim. In all of them the head is much broken ; but the rest of the body is beautifully preserved, showing most distinctly the vertebral column, ribs, fins, tail, and ventral spines. The single dorsal fin has its front rays about midway between the tip of the snout and the base of the tail, the ventral fins being immediately under the front of the dorsal and about mid- way between the pectoral and anal fins. The anal fin commences about halfway between the ventral fins and the base of the tail, occupying about two-thirds of that distance, and the tail is deeply forked. The scales are thin and in most cases much broken; while the ventral region of the body is armed with a row of strong spines. The spinal column contains about 40 vertebra, of which 14 or 15 are caudal. 'The bones of the head are mostly broken, but those of which the outline can be traced agree with the corresponding parts of the Sprat. These fishes are referred to the genus Clupea; but although very closely allied to the Common Herring and Sprat, the relative positions of the dorsal and ventral fins, as well as the number of vertebra, prevent their being placed in any known species, either recent or fossil, and they are therefore regarded as a new form and named Clupea vectensis. I1I.—December 5, 1888. —W. T. Blanford, LL.D., F.R.S., President, in the Chair. The following communications were read :— 1. “Notes on two Traverses of the Crystalline Rocks of the Alps.” By Prof. T. G. Bonney, D.Sc., LL.D., F.R.S., F.G.S8. Geological Society of London. 41 These journeys were undertaken in the summer of 1887 in the company'of the Rev. H. Hill, F.G.S., in order to ascertain whether the apparent stratigraphical succession among the gneisses and crystalline schists which the author had observed in the more central region of the Alps, held good also in the Western and Eastern Alps. At the same time all circumstances which seemed to throw any light on the origin of the schists were carefully noted. The author examined the rocks along two lines of section :—(1) By the road of the Col du Lautaret from Grenoble to Briancon, and thence by the Mont Genévre and the Col de Sestriéres to Pinerolo, on the margin of the plain of Piedmont. (2) From Lienz, on the upper waters of the Drave, to Kitzbuhel; besides examining other parts of the central range, east of the Brenner Pass. The specimens collected have subsequently been examined microscopically. The results of the author’s investigations may be briefly sum- marized as follows :— (1) While rocks of igneous origin occur at all horizons among the crystalline series of the Alps, these, as a rule, can be distinguished ; or, at any rate, even if the crystalline schists in some cases are only modified igneous rocks, these are associated with recognizable igneous rocks of later date. (2) There are, speaking in general terms, three great rock-groups in the Alps which simulate curiously, if they do not indicate strati- graphical sequence. The lowest and oldest resemble the gneisses of the Laurentian series; the next, those rather “friable” gneisses and schists called by Dr. Sterry Hunt the Montalban series; the third and uppermost is a great group of schists, generally rather fine-grained, micaceous, chloritic, epidotic, calcareous and quartzose, passing occasionally into crystalline limestones, and (more rarely) into schistose quartzites. (3) The Pietra Verde group of Dr. Sterry Hunt, so far as the author has been able to ascertain, consists mainly of modified igneous rocks, of indeterminable date, and is at most only of local, if, indeed, it be of any classificatory value. (4) Of the above three groups the uppermost has an immense development in the Italian Alps and in the Tyrol, north and south of the central range. It can, in fact, be traced, apparently at the top of the crystalline succession, from one end of the Alpine chain to the other. (5) The middle group is not seldom either imperfectly developed or even wanting, appearing as if cut out by denudation. It was not seen in the traverse of the Franco-Italian Alps, except perhaps for a comparatively short distance on the eastern side, being probably concealed by Palaeozoic and Mesozoic rocks on the western side. It is not very completely developed in the Eastern Tyrol, and seems to prevail especially in the Lepontine Alps, and on the southern side of the watershed. (6) The lowest group is fairly well exposed, both in the French Alps and in the Central Tyrol. (7) Asa rule, the schists of the uppermost group had a sedimen- 42 Reports and Proceedings— tary origin. The schists and gneisses of the middle group very probably, in part at least, had a similar origin. In regard to the lowest group it is difficult, in the present state of our knowledge, to come to any conclusion. (8) The slates and other rocks of clastic origin in the Alps, whether of Mesozoic or of Paleozoic age, though somewhat modified by pressure, are totally distinct from the true schists above men- tioned, and it is only under very exceptional circumstances, and in very restricted areas, that there is the slightest difficulty in distin- guishing between them. The evidence of the coarser fragmental material in these Palaeozoic and later rocks indicates that the gneisses and crystalline schists of the Alps are very much more ancient than even the oldest of them. (9) The remarks made by the author in his Presidential Address, 1886, as to the existence of a ‘“cleavage-foliation ” due to pressure, and a “stratification-foliation ” of earlier date, which seemingly is the result of an original bedding, and as to the importance of dis- tinguishing these structures (generally not a difficult thing), have been most fully confirmed. He is convinced that many of the con- tradictory statements and much of the confusion in regard:to the origin and significance of foliation are due to the failure to recognize the distinctness of these two structures. In regard to them it may be admitted that sometimes “extremes meet,” and a crystalline rock pulverized in situ is very difficult to separate from a greatly squeezed fine-grained sediment; but he believes these difficulties to be very local, probably only of a temporary character, and of little value for inductive purposes. 2. “On Fulgurites from Monte Viso.” By Frank Rutley, Hsq., F.G.8., Lecturer on Mineralogy in the Royal School of Mines. The specimens described in this paper were collected by Mr. James Kecles, F.G.S., close to the summit of Monte Vise (12.680 feet above sea-level). They are fragments of a glaucophane-epidote schist, in which garnet, sphene, and occasionally diallage are present. Prof. Judd considers that the rock somewhat closely resembles the glaucophane schists and eclogites of the Ile de Groix. The fragments are bounded by joint-planes or surfaces of easy fission, which are incrusted with minute pellets and thin films of fulgurite-glass forming the walls of lightning tubes. The glass was examined under the microscope (great care being taken to insure perfect isolation of the glass from the rest of the rock), and found to be, as a rule, remarkably pure, but in places not only gas-bubbles but also globulites occur, and the latter occasionally form longulites, and more rarely margarites. Microliths also are observable in some of the sections. In one section a minute rounded grain of schist containing a fragment of a strongly depolarizing crystal, probably epidote, appears to have been taken up in the glass. Where the glass comes in contact with the rock the latter appears to have undergone no alteration beyond the development of a very narrow band of opaque white matter, which the author gave reason Geological Society of London. 43 for supposing to be due, not to the action of the lightning, but toa pre-existent segregation of sphene. The occurrence of globulites, margarites, longulites, and micro- liths in the glass would seem to indicate a less sudden cooling than is assumed to be usual in such cases ; for the glass presents no signs which would characterize a subsequent devitrification or secondary change, and the bodies just enumerated appear, unquestionably, to have been formed during the refrigeration of the fulgurite. 3. “On the Occurrence of a New Form of Tachylyte in Association with the Gabbro of Carrock Fell, in the Lake District.” By T. T. Groom, Hsq. Communicated by Prof. T. McKenny Hughes, M.A., F.G.8. In this paper the author described an ancient but well-preserved glassy rock of basic composition which he had found as a vein associated with the gabbro of Carrock Fell. The rock was described macroscopically and microscopically, and a complete chemical analysis was given. The chemical composition resembled that of the more acid basalts and the augite-andesites, and approached especially closely to some continental basalts, analyses of which were added for comparison. Examined microscopically, the rock consisted of a globulitic and crystallitic glass-basis of green colour, containing spherules of quartz, spherulitic felspars, and an interesting series of granules and granular aggregates of augite, which likewise frequently assumed a spherulitic form. The rock was rendered microporphy- ritic by the sparing development of crystals (or skeleton-crystals) of plagioclase felspar, augite and quartz. The optical characters of each of the minerals were given. Owing to the mode of develop- ment and to the variety of its constituents, the rock possessed an exceedingly complicated structure. The order of crystallization was worked out, and it was pointed out that a second generation of each of the important constituents had arisen. The second generation of felspar was of a more acid type, and that of the quartz was devoid ‘of fluid vesicles, and had crystallized out after the rest of the rock had solidified sufficiently to form cracks. Close physical and mineralogical relations with the gabbro were indicated, and the author had no doubt that the two were in actual connection with one another. The age was put down as probably Ordovician. A comparison of the rock with other basic rocks showed that it had affinities both with the glassy forms connected with the more voleanic members, and with the variolites of Durance found asso- ciated with diabase. The relation with the latter rock was espe- cially marked, but important points of difference rendered a separa- tion of the two necessary, and for the new type of rock thus recognized the name Garrockite was suggested. This rock might be looked upon as a Quartz-Gabbro-Vitrophyre. 44 Oorrespondence—Ur. R. Lyjddeker ; Prof. T. G. Bonney. CORRESPONDENCE. IOHTHYOSAURUS ACUTIROSTRIS, ZETLANDICUS, & LONGIFRONS. Sir, —On page 313 of the Grotocicat Magazine, Dee. III. Vol. V. 1888, I stated that I was “disposed to unite both Ichthyosaurus Zetlandicus and I. longifrons with I. acutirostris. Since that passage was written Prof. Karl von Zittel has been good enough to send me a figure of an entire skull of an Ichthyosaurus from the Upper Lias of Curcy, evidently belonging to I. longifrons, which I consider inseparable from J. Zetlandicus. This specimen differs, however, from I. acuti- rostvis in its perfectly straight rostrum; and we have, therefore, a character which (if not merely sexual) will afford a valid distinction between the two forms. If I. quadriscissus of Quenstedt be identical with IL. acutirostris, the name FI. Zetlandiecus, as earlier than JI. longi- Jrons, should be adopted for the straight-beaked form. November 17th, 1888. k. LypEKKER. THE SERPENTINE OF THE LIZARD. Str,—There are two slight errors in Mr. Somervail’s paper “ On a Remarkable Dyke in the Serpentine of the Lizard” (p. 558 of last volume), which may mislead readers. They are contained in one sentence, “The dyke forms a portion of the ‘granulitic group’ of Prof. Bonney, which is now known to be of igneous origin.” (1) I have never placed any of the rocks near Pentreath Beach in my ‘“‘granulitic group,” but speak of them more than once as belonging to the “hornblende schists.” (2) For ‘which is now known to be” read ‘which is now known to include some rocks.” ‘The origin of the distinctly ‘banded gneissic” portion, like that of the banded hornblende schists, cannot be said to be yet known to any one, unless Mr. Somervail has been honoured with a special revelation on the subject. Most persons who have particularly worked at questions of this kind consider the origin of these rocks a very difficult and as yet unsolved problem. ‘The speculations as to the origin and relations of the Lizard rocks, with which Mr. Somervail has favoured us, will no doubt meet with the attention which they deserve, regard being had to the wide experience of their author and his intimate knowledge of rock-structures. T. G. Bonney. THE GENUS ASCOCERAS. Sir,—The figure which Prof. Lindstrom gives in the December Number,’ of an Ascoceras from the Island of Gothland is a very instructive one—as it supplies some of the earlier septa which have hitherto been wanting and gives a final proof of their existence. It is thus completely confirmatory of the description of the genus which I gave on p. 61 of my British Fossil Cephalopoda. At the time of writing I was obliged to say “the earlier part is unknown” —which still remains partially true—since only three chambers of 1 Grou. Maa. 1888, Dec. III. Vol. V. p. 583, Woodcut. Correspondence—Prof. J. F. Blake. 45 the ordinary type are seen in the new specimen; but I had to add ‘“‘the body chamber and the last few septal chambers only [those which are distorted] being preserved in association.” This is now no longer true, but the remainder of my description was entirely based on the probability, not to say the certainty, of such a specimen being ultimately found. It runs, “The earlier septa are of the ordinary kind, with very little convexity and the siphuncle is ex- centric, in some of large size... The last few chambers are distorted and their dorsal portions are seldom seen.” These dorsal’ portions, as in the specimen figured by Barrande (Syst. Sil. de la Bohéme, vol. ii. p. 513), are well shown in the new specimen. I arrived at the same conclusion as Professor Lindstrom—that the Ascoceras ‘‘is by no means the simplest form of Cephalopod, but the most abnormal,” and included it with Poterioceras and others in the group Inflati, the genus being characterized by having its “later septa distorted.” The group is said to diverge from the Conici, i.e. the Orthocerata, etc., and to be remarkable for the loss of the early septa. It is satisfactory that in all these points the new specimens from Gothland confirm the previous observations. J. F. Buaxn. THE MONIAN SYSTEM. Sir,—I feel greatly indebted to Dr. Callaway for introducing the Monian System to the notice of your readers. It was through his advice I went to Anglesey, and he naturally takes a fatherly interest in the result. There are, however, certain points in his “‘ Notes” which call for explanation or reply. 1. I am happy to recognize that Dr. Callaway, in 1887, quite independently of my observations, came to the conclusion that the hornblende-schists were of igneous origin, notwithstanding that such a conclusion entirely overthrew his reading of the succession in the ‘“‘oneissic series.” I must even confess that he is bolder than I am, for my statement that these schists are igneous, is made in fear and trembling; for though I am forced to it by the stratigraphy, I know it would have been laughed at a few years ago. Nor can I get as far as ‘foliated felsites,” those so considered by Dr. Callaway being compressed and indurated examples of the ordinary mica-schists of the district. 2. As to Parys Mountain, there are two other writers’ opinions to consider besides Dr. Callaway’s. 38. As to the Llanfechell Grit. I acknowledge it would be of some importance if it could be shown that any large part of the upper portion of the series was made up of fragments of the lower ; but after all the Llanfechell Grits are merely subordinate bands in a long series, and there are no conglomerates in association with them, so that at best any included fragments would be poor evidence. Moreover, it seems quite common in these old rocks, for the earlier deposits to be rapidly altered and to contribute to the later. Thus the con- 46 Correspondence—Prof. J. F. Blake. glomerate of Bull Bay is made of the underlying quartz rock. The fragments in the “agglomerates” or ‘“‘ conglomerates” of Llangefni are like some of the neighbouring rocks, the Bangor beds are full of fragments of rocks very similar to other parts of the same series, and the conglomerate of Moel Tryfaen is largely composed of the immediately preceding Cambrian slates. I do not, therefore, give much weight to any argument from such a grit. J only dealt with it because it was confessedly at first the only argument for there being “two groups of Precambrian rocks in Anglesey. Ifthe rock is dis- cussed, I have to say that of course Prof. Bonney’s description is accurate. The fragments do ‘‘much resemble some of the finer- grained schists of Anglesey ;” but they resemble those parts which have been entirely re-formed; such entire re-formation occurs some- times in bands parallel to the lamination, sometimes in veins crossing it, and is not confined to the older part of the series, but affects many other parts. The veins, like the rest of the rock, have formed under a pressure that has induced an orientation of the micaceous ingredient. We cannot, therefore, identify the fragments with any definite rock. 4, The rocks near Llyn Irefwll. In this case, again, I should have said nothing except for the stress Dr. Callaway lays upon the locality. I twice failed to find the exact spot referred to, though the whole structure of the surrounding rocks seemed clear. Only by the minutest directions was I able to find a spot where some slaty-looking rock contained fragments of granite, and seems con- tinuous with the diabase which forms part of several bosses. Ail these figure as “slate” in Dr. Callaway’s paper. Several slides have been examined and prove to be diabase—hence “some of the slates of Dr. Callaway are diabase.” Where the granitic fragments are found, this diabase has become more or less hornblendic, or dioritic—or it may be that the containing rock is a distinct one. In any case, fragments of granite are contained in a slaty-looking rock which is not a slate. They must also be contained in a true slate, since such is their matrix as described by Prof. Bonney; but this slate is certainly not the diabase ridge figured as Pebidian by Dr. Callaway. It is really not worth while pursuing the question any further. 5. With regard to the areas where there is a passage between Dr. Callaway’s lower and upper groups, his observations are rather special pleading, because ‘he selects two places, nearly the only two, where the succession is confessedly broken by faults, and gives these as examples ; whereas in both these places the supposed succession is stated to be entirely made out from what is observed abundantly elsewhere. 6. As to the applicability of the Monian system to other regions, it is obvious that our first business is to thoroughly understand the development of a series of rocks in the place where the connection of one part with another is most fully displayed, and such a place is Anglesey, where the succession and stratigraphy in many places is comparatively clear. It is a later work to correlate other regions with the type, the probable result only being briefly indicated in my Correspondence—Ur. C. Davison. AT paper. The reason for correlating the Longmynd rocks with the Upper Monian are, first, that they are certainly pre-Cambrian, especially since the discovery by Prof. Lapworth of the lowest Cambrian fauna in other rocks in the immediate neighbourhood, and, secondly, that the only certain fossils recorded from the Long- mynd, Arenicolites didyma, are also recorded from the rocks of Bray Head. It is also to be noted that as the “ Uriconian”’is to a large extent volcanic, there need not be much of a gap between it and the “ Longmyndian.” By some curious effort of the imagination Dr. Callaway says “‘ Uriconian and Malvernian are lumped together as Middle Monian,” but I cannot find that I have anywhere mentioned the ‘“ Malvernian,” as I know too little of that district and the descriptions are too discordant to make it safe even to venture upon a probability. It may not be Monian at all. If Dr. Callaway has a fancy to call the different divisions of the Monian by names derived from other districts, there can be no objection, provided we first make sure of the correlation. J am perfectly satisfied with their all forming parts of a larger group or system—the Monian. I may add that as these rocks have a quite distinct character from the true Hebridean, or the general type of gneisses, I was much delighted to find that so many foreign geologists, who visited Anglesey in September last, recognized their resemblance to rocks of their several districts which occur immediately beneath their lowest fossiliferous horizons. J. F. Bras. Dec., 1888. UNIFORMITY IN SCIENTIFIC BIBLIOGRAPHY. Srr,—Having been for some time engaged in preparing a biblio- graphy of earthquake-literature, I can fully endorse the necessity of Mr. C. D. Sherborn’s plea for uniformity in the quotation of abbreviated titles of scientific journals. The increasing number and importance of works of this class render this and other unsettled points in bibliography worthy of attention and discussion; and I would venture to suggest that the British Association Committee on Zoological Nomenclature could find a useful successor in a Committee for securing Uniformity in Scientific Bibliography. May I be allowed to offer here a few remarks on this subject ? Abbreviated Titles.— Besides a mere hap-hazard choice two courses are open in the selection of abbreviated titles. (1) We may adopt that in use amongst the members of the Society issuing the journal, as “ Phil. Trans.” or “Comptes Rendus.” Familiarity in a few cases and established custom are in favour of the retention of this system, but it has the obvious disadvantage of not representing at a glance the complete title of an unknown journal, for it omits the name of the society. Moreover, contractions founded on such words as “Transactions” or ‘ Proceedings,” common to a great number of societies, are objectionable. (2) The abbreviations may be formed on a uniform plan from the full title of the journal. That adopted in the Geological Record 48 Correspondence—Rev. O. Fisher. seems to me to fail in putting to the front a word like “ Trans.,” a comparatively unimportant part of the title, and also a word common, as just pointed out, to many different Societies. A better method would, I think, be to put the most important, and at the same time least-frequently used, word first, and the others in descending order, as follows: 1. Place of meeting: 2. Name of society : 3. Name of journal: e.g. Glasgow, Geol. Soc., Trans. I may remark, in passing, that this system is used in the library of the Birmingham Philosophical Society. It possesses the advantage that the book-shelves form an alphabetical index to their contents. Obvious exceptions to the rule will occur at once, some as neces- sary, others as desirable. The British Association Reports cannot be classed under the name of any town; and it would hardly be advis- able, for instance, to subordinate the well-known Transactions of the Seismological Society of Japan under the less-known heading “Tokio.” The name of the country should clearly be used when it occupies the leading place in the title. Date of papers.—The date of a paper contributed to a society may be taken as that of its reading, or as that of the publication of the volume in which it appears: these dates often differing considerably. The latter, I believe, is the method usually adopted. But, in a case of priority, this rule would not be followed; and a paper may also become widely known by means of ‘authors’ copies” printed off before the complete volume is published. On these accounts, it seems to me desirable that the day ou which a paper is read should be accepted as its date in bibliographies. CuarLes Davison. Kine Epwarp’s Hieu Scuoor, Brrmincuam, Dec. 7, 1888. THE BEDS OF THE LONDON AREA. Srr,—In the short abstract of Mr. Whitaker’s paper on the Streat- ham boring, read before the Geological Society on the 21st November, the question is raised as to the horizon which the generally red beds met with beneath the Mesozoic in many of the deep borings around London occupy between the Trias and the Devonian. It has appeared to me that they probably belong to the former, because the rocks met with at Meux’s Brewery in Tottenham Court Road, and at Turnford, are distinctly of the Devonshire type. Now, so faras I know, the “ Devonian” does not assume the Red Sandstone type in Devon- shire. If this is so, then it offers a presumption that, where these older beds are found of the Devonshire type, as is the case under London, they are not likely to be found also of the arenaceous type, which belongs to those in the Mendip and South Wales district. In fact the two types are not likely to be found together in the same area, unless it happens to have the exceptional position of being situated where two distinct conditions of deposition succeeded one another during one and the same geological period. For these reasons I think these red beds newer than the Carboniferous. Harton, CaAmMBripGE, Dee. 11, 1888. O. FisHer. = . = Oe THE GEOLOGICAL MAGAZINE. NEW SERIES. “DECADE Wi eV@Es Vv |. No. II— FEBRUARY, 1889. Crebreaepian, /Naenidese, 1S. a J.—On some Puysican Cuaneus In THE Harrn’s Crus. (Part I.) By Cuartzs Ricxerts, M.D., F.G.S. es always appears an objection to the agencies by which mountains and hills are formed being designated by such terms as “mountain architecture,” ‘mountain building,” etc., leading to the inference that to the deposition of the materials which enter into their composition these elevated regions owe their form and structure. There certainly are mountains which have been built, and some such are at the present time in process of building; but these instances refer only to elevated masses of volcanic origin: they have been constructed as the railway engineer builds his embankments, or, with greater preciseness, as the miner forms the bank at the pit’s mouth, by tipping over the rubbish brought from below. To hills and mountains forming volcanic cones the term mountain building is quite correct; the volcano in eruption pouring over its lava, and belching forth scoriz and ashes, which fall and accumulate around its vent. The term building may also be applied to the formation of the miniature mountain-ranges which, in certain localities, fringe our coast; sand-hills and -dunes being due to the accumulations which the wind has carried landward when the sandy shores are exposed and dry. The term is likewise applicable where receding glaciers have brought down, and discharged as moraines, their burden of stones and rubbish, forming not only small mounds but hills and ridges of considerable size. With respect to elevated masses such as these, whether great or small, the process of their formation may be correctly termed building ; otherwise the formation of mountains is due to sculpture, —to erosion, disintegration, denudation,—and may be compared to the work of the quarryman, rather than that of the builder; to the art of the sculptor and not of the architect. Playfair, in his ‘Tllustrations of the Huttonian Theory of the Earth,” considered that “ mountains as they now stand may not inaptly be compared to the pillars of earth which workmen leave behind them, to afford a measure of the whole quantity of earth which they have removed.”* 1 § 113, p. 127. DECADE III.—VOL. VI.—NO. II. 4 50 Dr. C. Ricketts—Changes in the Earth’s Crust. Excepting by very few it was formerly assumed that the sculpturing of mountains, and the formation of valleys, etc., were due to the action of the sea. Again, that ‘‘ the excavation of valleys could be ascribed to no other cause than a great flood of water, which overtopped the hills from whose summits these valleys descend.” It has been considered “they are due to cracks, rents and gorges of fissure in the rock-masses, in some of which rivers flow ; that these fissures have been caused by upheaval, by ruptures, and denudation,” and “that mountain valleys lie in lines of cur- vature, dislocation and fracture.” No endeavour was made to demonstrate how any of these various causes could have excavated valleys, and it is very remarkable that there was no attempt to account for the redistribution of the materials which had been removed. It is probable that the difficulty of making the present conformation of the Harth’s surface coincide with a preconceived chronology, may have had great influence in the formation of such opinions, even by those who are justly considered fathers in geological science. We are constantly reminded how greatly this feeling is impressed on the popular mind in expressions made by persons unacquainted with geological science; with those who may be considered educated, ‘“‘I presume it is antediluvian ;” with the workman or labourer, “It was there afore th’ flood!” Walking through one of the minor gorges in the Carboniferous Limestone of North Derbyshire, and conversing with an intelligent man native to the district; on the remark being made, that some persons think these dales have been formed by the streams that run through them, the immediate and emphatic reply was, ‘No! that could never be;” and, pointing to the rivulet, ‘Why there is not water enough to drown a mouse. You may depend upon it all these places were cut out when the world was drowned.” Hutton (1795) and Playfair (1802) demonstrated that the for- mation of valleys was due to the effects of atmospheric agencies. Playfair says, ‘“‘ Water in every state from transparent vapour to solid ice, from the smallest rill to the greatest river, attacks what- ever has emerged above the level of the sea, and labours incessantly to restore it to the deep. The parts loosened and disengaged by the physical agents are carried down by the rains, and, in their descent, rub and grind the superficies of other bodies ; and, when rain descends in torrents, carrying with it sand, gravel, and fragments of rock, it may be truly said to turn the forces of the mineral kingdom against -itself. Every separation which it makes is necessarily permanent, and the parts once detached can never be united save at the bottom of the ocean.”! ‘All river channels have been cut by the waters themselves ; they have been slowly dug out by the washing and . erosion of the land.’’? A long time elapsed before this explanation was accepted, not until there occurred in the early volumes of the GroLtocicaL MaGazINE a prolonged discussion on the subject, which proved that a great 1 Playfair's Illustrations, etc., § 95, p. 111. 2 Tllustrations, § 99, p. 114. Dr. C. Ricketts—Changes in the Earth’s Crust. 51 change of opinion had taken place; very many of those who had _ been led to consider that, in the words of Hutton, “the rivers them- selves had hollowed out their valleys,” being on the staff of the Geological Survey, whose occupation affords special opportunities for determining such questions; not that they ignored the effects of the waves and tide, but did not attribute to them results which the sea could not produce, occurring where the sea had not been. The author of “ Rain and Rivers” (the late Colonel George Greenwood), was the most persistent advocate of the views of Hutton and Playfair. This dashing cavalry officer renewed the assault again and again, never failing to attack any weak point exposed by his opponents. This discussion was decisive in determining that valleys are formed by rain and rivers, and that the materials, which once filled up the excavations made, had been carried down and deposited in the sea near their mouths; but there still remained to be considered the methods by which this is accomplished. If the crust of the earth were rigid, rivers, by bringing down the disintegrated materials, would simply fill up the sea near their mouths, and, judging from the vast amount which must, during prolonged periods, have been removed in the excavation of valleys, there would be formed level | plains or deltas extending over an immense number of square miles, through which the streams would flow. At the mouths of large rivers. and where the sediment derived from the excavation of the land is brought down by them, there is evidence in all cases that the weight of these accumulations in the bed of the sea, on deltas, and in bays, presses down the crust of the earth, and thus accommo- dates the subsequent accretion of materials. This result may be considered universal and capable of demonstration in strata of all ages, from the earliest Geological epoch to the present time.’ No expression is in more frequent use than that different formations have been laid down during a period of subsidence. «« Everywhere throughout the world,” says Prof. James Geikie, “we read the same tale of subsidence and accumulation, of upheaval and denudation. It has only very lately been generally recognized that the weight of the accumulation is the cause of subsidence; at all events when, in a consideration of the subject,’ opportunity was afforded, there was no attempt to controvert this opinion. The subject is a most important one, and, with its converse, that denuda- tion, by lessening the pressure on the earth’s crust, causes the land to rise, may justly be considered the Alpha and the Omega of physical geology, for to it must be attributed the great movements and changes that take place on the earth. These areas of deposition may subsequently enter into the structure of mountain-masses and form elevated ground, but, so far as building 1 On Subsidence as the Effect of Accumulation, by C. Ricketts; Grou. Mac. Vol. [X. p. 119, 1872. 2 Mountains: their Origin, Growth, and Decay. 3 “ Nature’? for August 2nd, 1883, and subsequent numbers. In the number for August 30th, 1883, page 413, and October 4th, 1883. page 539, reference is directed to those who have taken the subject into consideration so far as known to myself. 52 IDO Ricketts—Changes in the Earth’s Crust. is concerned, the result is the formation of alluvial and marine plains, occurring about or below the level of the sea; it is only on the conditions being altogether changed they become raised, chiefly in consequence of the removal of weight, consequent on the great denudation they have undergone, and thus help to form mountains. The flanks of mountains are frequently composed of rocks whose strata have undergone disturbance and contortion, and are oftentimes affected by cleavage. These foldings have been referred to as essential features in the formation and “building” of mountains ; but they extend as frequently to low ground, and pass beneath deltas and estuaries, and form the base upon which the strata con- stituting the bed of the sea rest. Geological inquiry shows that after having been raised above the sea-level and become weathered and eroded, the valleys and channels formed may again be sub- merged, and have their weathered surfaces buried beneath sediments to a depth of several thousand feet. Contortions have been attributed to the forcing of wedge-shaped masses of metamorphic rock upwards so as to penetrate and protrude through sedimentary strata; but in a general elevation affecting a district the whole thickness of the’ earth’s crust must be lifted together, and from a depth which would render such an occurrence impossible. In no instance would it appear more probable that such has taken place than on the flanks of the Malvern Range, had not Miss Annie Phillips’ (sister to the Oxford Professor) found Silurian organisms embedded in a breccia derived from the dis- integration of the metamorphic rock. Her discovery was most important, more so than is generally recognized; proving that during the deposition of the Upper Silurians the Malvern Hills formed an Island, in all probability the summit of a former mountain, buried beneath a great accumulation of strata then in process of deposition, the margins of which consisted of fragments of the metamorphic rock which had fallen down from its sides into the Silurian sea.? The contortions in these Silurian strata, or the power that caused them, could not have given origin to the mountain, for its summit was situated above the sea-level during the time of their deposition ; on the contrary, its presence may have influenced but not caused, that action by which they are thrown into extensive folds. The rudder does not cause the ship to sail, but determines the direction of its course. Any movement by which the crust of the earth is compressed into a less lateral space must, to an extent commensurate with the size of the area effected, have a tendency to cause the strata to become bent and contorted. This may result in some degree from the weight of accumulations causing subsidence, and, by thus pressing downwards the earth’s crust, cause it also to be compressed within less lateral dimensions, but the lateral pressure thus developed can only be considered as inducing a tendency to form flexures ; its 1 Memoirs of the Geological Survey, vol. ii. p. i. p. 66. 2 Fragments derived from the hills also enter into the composition of the Holly- bush Sandstone (Lower Silurian). W. M. Hutchings— Altered Igneous Rocks, Tintagel. 53 extent being limited to the difference between the measurement of the portion of the earth’s circumference and the Chord of its Are included in any area referred to. This variation will be found comparatively so slight as to be utterly inadequate to account for the presence of such foldings as occur in many districts; though it is to such a cause they are not infrequently attributed. The impossibility of these contortions being the result of such subsidence may be best illustrated by taking two slips of wood (Fig. 1 a, 6) of equal length —say 10 feet—fastened together at one end by a hinge (c) ; one (a) being fixed so as to remain straight, the other (b) bent to represent a curve, the greatest distance (d) between the chord (a) and the curve (b) being six inches; it will be apparent that the distance between the extremities of the slips of wood will be very slightly over three-quarters of an inch (e) ; an amount too insignificant to be ae eee capable by the pressing down of the one upon the other to form foldings such as are frequently met with in geological formations. (To be continued.) IJ.—Nores on Autrerep Ienrous Rocks or Tintacen, Norra CoRNWALL. By W. Maynarp Hurcuines, Esq. hee the autumn of 1887, during a stay in North Cornwall, I paid ia hasty visit to Tintagel, and took away a few specimens of rocks, without, however, having time or opportunity to examine more than very superficially into their field-relationships. In subsequently studying sections with the microscope I found myself unable to correctly interpret some of them, notably a certain highly schistose rock consisting mainly of calcite and chlorite, with residues of triclinic felspars. Mr. Teall, who very kindly looked over several sections for me, suggested that this was a highly altered and mechanically metamorphosed igneous rock, which might prove to be derived from a certain epidiorite occurring not far from it; and made other remarks and suggestions which decided me to pay another and longer visit to Tintagel in the following year. _As a result of this visit, and the subsequent examination of a series of rock-specimens then collected, I venture to offer a few notes on the altered igneous rocks of the coast in the immediate vicinity, viz. from a point near Boscastle to the south end of Trebarwith Strand. The more or less altered ‘“Greenstones” of the coast further south have been studied and described to a considerable extent. A résumé of the work done is given and discussed in Teall’s “ British Petrography.” So far as I am aware, the corresponding rocks of 54 W. MW. Hutchings—Altered Igneous Rocks, Tintagel. the more northern part of the coast have not received a similar amount of attention. Referring to the map of the Geological Suitey of the district, we find no occurrences of “Greenstone” marked along the coast, or its immediate vicinity, from the neighbourhood of Port Isaac to that of Tintagel, where several outcrops are indicated, extending along to near Boscastle, where we pass from the Devonian to the Carboni- ferous rocks. There are, however, other prominent occurrences of greenstone around Tintagel which are not shown on the map, notably the very extensive exposure at Trebarwith Strand which is alluded to by De la Beche in his “‘ Report of the Geology of Corn- wall, Devon, and West Somerset” (1839). In this report there are several references to the igneous rocks of this special strip of the coast. Thus, on pp. 56 and 57, Beche speaks of ‘“‘schistose beds” which are intermingled with the “slates and grits which emerge from beneath the Carboniferous system,” and describes these schistose rocks as “strongly reminding us of the substance of greenstone, finely comminuted and permitted to settle in water in which calcareous matter was occasionally present.” He states that “ greenstones, some large-grained, occur near Tintagel, and the trappean schistose rock is also discovered mingled with them, particularly towards Bossiney.” He looks on the “ schistose trappean rock” as an altered ash, and considers that the two kinds, compact and schistose, have “ probably been erupted, one in the state of igneous fusion, and the other in that of ash, during the time that the mud now forming slates was deposited.” This sharp distinction made by Beche between the compact and schistose rocks of this neighbourhood, and the definite inference he draws as to their different conditions of origin, would not now, with modern methods of examination, hold good in all cases. Passages of his “large-grained” or ‘‘compact” greenstone into the most highly schistose rock may be observed which leave no doubt that the original material was one and the same for both. There are other occurrences of schistose rock whose origin we may safely say was igneous, but concerning which, in their present extremely altered condition, we could not arrive at any safe con- clusion as to whether they have been derived from massive or fragmental material. The occurrence which I will first notice is seen in the cliff at the side of a cove which is not named on the map, and of which I heard no name on the spot. It is the next little inlet sonth of Bossiney Cove, separated from it only by the neck of land off which lie the rocks called “The Sisters.” The exposure in question is at the south side of this nameless cove. There is an outcrop, at the surface above the cliff, of angular craggy blocks, and the continuation may be seen dipping steeply down towards the sea. At the outcrop the rock is coarse-grained and massive, showing no foliation at all. It is very hard ane tough, making excellent road-metal, for which purpose it is taken in quantity ‘from a similar outcrop in a field a W. M. Hutchings—Altered Igneous Rocks, Tintagel. 58 little way off. Numerous large irregular grains of hornblende are seen set in a greenish-grey speckled mass. It is doubtless an ex- ample of the “ large-grained greenstone ” alluded to by De la Beche. A little way down the cliff the rock becomes much foliated, is much altered in general appearance, and is softer; and still further down, near the water, it has become very highly schistose, tolerably soft and easily fissile, differing in appearance in every way from the rock at the outcrop. Foliation is coincident with the dip and with the cleavage of the slates, shales, etc., above and below. Specimens were taken at three points: No. 1, outerop; No. 2, a few yards down the cliff; No. 8, near the bottom, a few yards above the level of the sea. Microscopic examination of sections from these specimens shows internal changes corresponding to the outward differences in texture and general appearance. No. 1 is essentially a hornblende-plagioclase rock. The horn- blende is all green, secondary and uralitic. It is mostly pale in colour with very moderate pleochroism, but some portions are of a much deeper colour and powerful pleochroism, the contrast being often seen in contiguous parts of one individual, one portion being nearly colourless, and the other a very deep green, though they ex- tinguish together and give nearly the same colours of polarization. The felspar is nearly all very turbid, but the columnar form of many of the crystals is still perfect, and they are still fresh enough to show twinning, binary and multiple. The structure of the original rock is shown to have been markedly ophitic by the fact that many of the individuals of hornblende are penetrated by felspar crystals, in some cases being nearly bisected. Crystals of apatite are seen here and there. There is comparatively little chlorite or calcite, but epidote is abundant, both in finely granular form in the hornblende and in crystals and irregular fragments and grains all over the sections. It is all quite colourless and non-dichroic. Leucoxene is plentiful in large plates and patches surrounding varying amounts of residual ilmenite; and some granular sphene may be seen. There are grains and little patches of secondary quartz, and a very few bits of perfectly water-clear, obviously secondary felspar, without any trace of definite form or of twinning, recognized by its optic behaviour. This rock is a typical epidiorite, of which we may say with tolerable certainty that it was derived from a coarse-grained ophitic dolerite. Sections of No. 2 show that hornblende is much diminished in quantity, with a corresponding increase in chlorite. All stages may be seen of the passage of the hornblende into chlorite. Calcite is, also very much increased in amount. The felspar is largely in the state of a confused, crushed, turbid mass mixed up with chlorite, without any form or sign of twinning, but with this there are a very large number of bigger grains and patches which are water-clear and contain needles of hornblende in some cases, together with numerous grains of chlorite. But few of these water-clear bits show any twinning. Quartz has increased 56 «=W. Wl. Hutchings—Altered Igneous Rocks, We tntagel. also considerably in amount. Leucoxene and epidote remain in about the same proportions as in No. 1. But it is more the mechanical than the chemical or mineralogical change which is very striking in this part of the rock. It has become very much foliated, and sections cut across the schistosity show in a beautiful manner what a great amount of stress and internal movement it has undergone. 'The chlorite is drawn out into long, curving parallel bands and streaks, and most of the calcite and leucoxene have been squeezed out into long lenticles, tapering off into thin tails. Hornblende also is crushed into layers, but in a less degree, and much of it is now in the form of detached needles and fibres. Epidote has not been drawn out into streaks, but is more broken up and separated and more or less arranged in lines; and the irregular bits of this mineral lying in among the bands and lenticles of the other constituents which have behaved more plastically, often serve to more distinctly mark the amount of ‘ flow” which has taken place around their angles. It would be difficult, I imagine, to find anywhere a more striking example of the great alteration which may be effected in rock-structure by pressure and shearing-movement than is here given within a space of some thirty yards or less. Sections of No. 3 show that hornblende has wholly disappeared, chlorite taking its place. Calcite is more abundant than in No. 2, while epidote is nearly wholly absent. It may be stated that over a large number of sections of rocks of this district which I have examined, calcite and epidote very generally appear in’ inverse proportions. They are, of course, very liable to be originally developed in inverse proportions. They both originate from the alteration of the same calcareous silicates, and varying conditions under which this alteration is carried on may give rise to varying amounts of the two minerals in question, even in closely adjoining parts of a rock. But it seems not unlikely that epidote may be altered into calcite under some circumstances. I have seen no mention of this, nor have I detected any epidote actually under- going the change to calcite. Nevertheless, the frequent oscillation in the relative amounts of the minerals in these rocks has constantly suggested such a change, which is likely enough from a chemical point of view, as a possible explanation. The most striking change in No. 3, as compared with No. 2, is that turbid felspar has now almost entirely given way to water- clear. Much of it here shows twinning. It is more or less full of bits of chlorite, and other mineral enclosures which cannot be determined. Onente has undergone a further very decided increase. Leucoxene is still abundant, but some patches of it are seen to be very much altered to rutile in grains; and small crystals of rutile, some as sagenite, are Abnea in some parts of the chlorite. The foliation is seen to be more highly developed, the parallelism of the bands of chlorite, ete., being greater, and their course less curved and wavy, which corresponds with the much greater tendency of this part of the rock to split into flattish pieces. W. M. Hutchings—Altered Igneous Rocks, Tintagel. 57° I may here mention that it was a section of this schist which Mr. Teall saw, together with a piece of the epidiorite, though from another outcrop. His suggestion that they might prove to be directly connected in derivation was made at the time without the slightest knowledge of the actual field-relationships, but has proved to be perfectly correct. We have here, then, a very interesting case of the passage of a massive epidiorite into a perfect chlorite-schist; and doubtless a further series of specimens, taken at shorter intervals, would prove very instructive. ; This sheet is of but moderate thickness—a few feet only. It appears to be separated from a very much thicker sheet, which underlies it, by a bed of shale or slate, the contact with which is well seen at the lower part of the cliff. Concerning the question as to whether this and other sheets of igneous material to which I shall allude are intrusive or contemporaneous, it seems that De la Beche regarded them all as being the latter. So far as my own observation goes, I should incline to hold the same opinion, at least. as concerns those exposures where a considerable extent of the upper and lower contacts with the slates, etc., is plainly visible. But I would express this opinion with much diffidence, in view of the great. disturbances which have everywhere taken place in this district, and the great amount of alteration the rocks have undergone. The sheet just considered appears to follow the curve of the coast and to wind round towards Barras Nose and the Castle Cove; but much of the intervening shore is inaccessible and examination could not be made. About two-thirds of the way towards Barras Nose there is another outcrop of chloritic epidiorite, intermediate in nature between No. 1 and No. 2. In the Castle Cove is exposed a sheet of rock which I am inclined to think is very likely a continuation of the one just described, though it is not possible to trace the connection to the point of proof. The nature of the rock is here different in many respects, but nothing is more striking than the considerable and often rapid changes of character which the igneous rocks of this district show. The sheet I allude to is seen on both sides of the Cove. On the left it is inaccessible in the cliffs of “Tintagel Head,” but on the right it may be freely examined. Jt overlies a bed of black shale, with which its contact is sharply defined ;—the same bed of shale which, curving steeply upwards from the Cove, passes right under a portion of the “Mainland,” part of the Castle. So that originally this sheet of igneous rock swept up over the country inland, but is now wholly removed by denudation. As seen at the right-hand side of the cove, where the fishing-boat is hung on davits, it is a hard, grey, rather fine-grained, moderately-foliated rock. It is a good deal jointed and cracked, and all these cracks are filled with quartz. This is the only case in the district of an igneous rock being veined with quartz instead of the usual calcite. The microscope shows it to consist mainly of felspar and chlorite, without any trace of original ferro-magnesian mineral or of secondary 58 W. M. Hutchings—Altered Igneous Rocks, Tintagel. hornblende. The felspar is much the predominant constituent, and part of it is better preserved here than in any other local rock I have examined. Much of it is again in the indefinite and untwinned water-clear condition, but with this there are a great many well- twinned crystals of columnar form. Binary twinning is most prevalent. A series of measurements of maximum extinctions shows that much of the felspar belongs to the labradorite-anorthite group, though more acid felspars seem to be present, most likely of secondary metamorphic origin. Chlorite and calcite are in only moderate amount. Secondary quartz is tolerably plentiful, both in grains of good size and as a mosaic of smaller ones. Leucoxene with residual ilmenite, granular sphene, a little epidote, apatite, small flakes of biotite, and rutile in slender needles, and bunches of needles go to make up this rock. Bent and broken crystals of felspar, and strongly undulous extinctions both of felspar and quartz, bear witness to severe strain. The fact that much of the quartz shows these effects of stress goes to prove that_the rock was very much altered before this stress was applied. In the centre of the Cove, almost under the waterfall, another exposure of igneous rock is seen, quite at the bottom of the cliff. The extent of it visible is small. It makes the impression of being the upper part of a curve or fold of a sheet. If this is so, and supposing the sheets to be contemporaneous and not intrusive, this rock is older than the last described, considerable thickness of sedimentary material intervening. This rock is very schistose. it is highly altered, very little of its abundant felspar having any definite formas compared with the last. Calcite, chlorite and quartz are in large amount, there is also much ilmenite in various stages of alteration to leucoxene, and many of the large patches of chlorite are full of beautiful sagenitic rutile. Again, passing from the Castle Cove hy the path between the mainland and the so-called “island” of Tintagel Head, and de- scending to the shore below the steep west cliff of the mainland part of the Castle, we come upon a section of several sheets, or. bands, of igneous rocks of various thickness, with intervening black shale. The upper sheet is some feet in thickness, then comes a bed of shale in which are two or three sharply separated bands of igneous rock of a few inches only, and finally a lower sheet of which some four to six feet are seen. hey are only exposed for a few yards. It is not possible to make out anything with certainty, but very probably the upper portion of this exposure is connected with the rock seen near the waterfall in the Castle Cove. I have examined specimens from the upper band of the series. It is again a very schistose rock. Microscopically it is interesting because it contains a good deal of what may undoubtedly be con- sidered to be original igneous structure. The felspar, very abundant, is partly turbid and partly water-clear, and all the larger individuals are more or less full of flakes of muscovite. Crystal forms are well retained, and twinning, both binary and multiple, is very little obliterated. Tabular crystals are most numerous, but columnar Prof. O. Lapworth—Ballantrae Rocks of South Scotland. 59 shapes are also well represented. Besides the large crystals, how- ever, there are a considerable number of much smaller lath-shaped felspars. These are all water-clear, well twinned, and quite fresh as to optic qualities. They all extinguish at very small angles. There is no sign of any original ferro-magnesian mineral, which is now only represented by abundant chlorite. There is much leucoxene; but little sphene or rutile. Broken, bent, and optically strained crystals are in plenty here as in the other rocks. The two rocks of the Castle Cove may have resulted from the alteration of either massive or fragmental igneous materials; the microscopic study of them does not afford sufficient evidence for decision one way or other. But the structure of the rock just described seems plainly to show that it was a massive one, its numerous larger felspars set in a ground-mass of which the smaller lath-shaped crystals formed part. It was probably a basic rock, though much of its felspar seems now altered, by dynamic meta- morphism, to mere acid forms. The main occurrence of altered igneous rock in this district, however, is on a very much larger scale than any of those above described, and forms, indeed, one of the principal features of the coast at some parts of the parish of Tintagel. (To be concluded.) IJJ.—On tHe Batranrran Rocks or SourH ScorLanD AND THEIR Piace in THE UPnanp SEQUENCE. By Pror. Cuartes Larworrn, LL.D., F.R.S., F.G.S. (With Plate III. and a folding Table extra). (Concluded from page 24.) Part II.—The Sequence in the Southern Uplands. EXT to the metamorphic region of the Northern Highlands there is perhaps no area in Britain where the strata have been so contorted and convulsed as in the great Lower Paleozoic region of the Southern Uplands of Scotland, and it is only by the zonal method of stratigraphy that these complexities can ever be successfully unravelled. So far as the present results of the appli- cation of that method enable us to judge, it appears that, underlying all these stratigraphical complexities, there is, in reality, a broad tectonic structure of great simplicity. For, if we make exception, on the one hand, of the lowest strata (the Ballantrae or Arenig rocks), which, as we have seen, only rise to the surface within the limits of the Ballantrae district ; and on the other hand of the highest formations (Wenlock-Ludlow), which merely skirt the Upland plateau upon its north-west and south-west flanks, we find that almost the whole of the Lower Paleozoic strata of the Uplands are naturally grouped in two grand lithological terranes, viz. (I.) a Lower Terrane (Moffat Terrane), including strata ranging from the Upper Llandeilo to the Upper Llandovery ; and (II.) an Upper Ter- rane (Gala or Queensberry Terrane), embracing strata generally of Tarannon age. 60 Prof. C. Lapworth—Ballantrae Rocks of South Scotland. The rocks of the Lower or Moffat Terrane attain their maximum. development in the Ballantrae-Girvan district to the extreme north- west of the Uplands. In this district the terrane is made up of the three successive local rock-formations which have been termed by myself! (a) the Barr or Stinchar Series (of Bala-Llandeilo age), | (6) the Ardmillan Series (of Bala-Caradoc age), and (c) the New- land Series (Llandovery). Its strata are here very varied in litho- logical character, contain an abundant fauna of all the usual Lower Paleozoic life types, and have an aggregate thickness which has been estimated at about 4000 feet. Followed thence, however, as they reappear in the many antielinal forms of the Uplands towards the south-east, they diminish very rapidly in vertical extent, — until, when we reach the Moffat district (50 miles to the south-east- ward), the strata of the entire terrane are reduced to a collective thickness of 300 or 400 feet. In this district also they have lost their original varied lithological characters, and have dwindled down into a comparatively homogeneous mass of black, grey and white shales: while their diversified fauna has degenerated into one almost exclusively Graptolitic.? Nevertheless, in spite of the re- markable attenuation of the strata of the terrane, its three component formations are still recognizable as the three local divisions of the Moffat Series, (a) Glenkiln Shales, (b) Hurtfell Shales, and (e) Birk- hill Shales. Paleeontologically these answer broadly to the three Girvan divisions, the Graptolites characteristic of the lowest Moffat or Glenkiln Shales being equally characteristic of the lowest or Stinchar formation of Girvan: those Graptolites in the second or Hartfell division being found in the second or Ardmillan formation of Girvan: while those of the highest or Birkhill shales agree precisely with the forms characteristic of the third or Newland formation of Girvan. This parallelism is not only evident as respects each of the three successive subfaunas, but many of the subordinate zones in these widely separated districts admit of an equally satis- factory parallelism in sequenee and in lithology, as well as in characteristic fossils.? To the south-west of the Moffat district the rocks of the Moffat Terrane soon plunge below strata of more recent age, and are seen no more within the limits of the Scottish Uplands. They must, however, still retain their attenuated and deep-water character for many miles in their subterranean course in this direction; for when they re-emerge in the Lake district (as the Coniston Lime- stone Group and Skellgill Graptolitic Shales), their middle members (Coniston Limestone Series) have only gained a few hundreds of feet in collective extent, while the strata of their highest division (Birk- hill or Skellgill Shales) are practically unaltered in lithology, thick- ness, and in fossils.‘ Graduating upward conformably from the highest beds of the 1 Lapworth, Girvan Succession, Q.J.G.S. 1882, pp. 5387-666. 2 Ibid, Moftat Series, Q J.G.S. 1878, pp. 240-346. 3 Compare Tables Q.J.G.S. 1882, p. 660, and 1878, p. 250. * Marr and Nicholson, Q.J.G.S. 1888, pp. 706-708. Geol. Mag.1889. GEOLOGICAL SECTIONS THROUGH THE ANOLD 8 e : Be ee Se) & diag nwoigea pe | D> iN S poy PL ET & YALU NIHLIFT y S SSH NIFATY ¥ Am oN L9 PONT 7 eS K ay ee pel. a s S A Si Sa QQ s77/ 43HLMOT € j 8 iS ft OT ~-7: ‘| 8 Y — sede AS a 5 ee kn019.aygMoT 27 Se N 5 ae 8 Be gS Sree ans es -“STMVHOFIT —= y FAOWVIVY TS = = es f are é sa&20/9 = iN XQ a) R00f00 SIZ. 7 \ d UuBeydSi7 = Gor <= = 2 foe Sear Sie S eee 2) eS x . TAP??PT 1 F 7) os TN S OLD 42YMOT ET | Rp ENT OT OE Sig poy sibbar og \ eB oh : eget! Baer LNIYD fj i, Piast ie ‘ NUNGOVIT s Bos SLY PATIO WH Pere) fn TCS as gee HS “S aS sia SYIORT SOLA PNOGLE & SILI KA \ ( C ; \ SAOTHUP Cgc) CIEE NLA, S ‘ \ 4 ms) 4 on) 2) cL xs aS) SPOT * TMT If A024 PVPUAT 8 : = sniAdhingy Oey ) sno.afiUog.2 7 8 : R > MODUVHVNSA7] iY \ \\ \ Ss iG ty = aeugspuns \\W\\ = v X azy a79¢IMo7 \\ in \ LEADHILLS DISTRICT 4 LESH MAHAGON DISTRICT Western_Distr: VG INWONOT SYIO DERG ERILZ cc af 40 LOOSTHON aw se Tip NIVIN A - j , é , SS a BENNANE HEAD BALLANTRAE DIST. Yy NX S g (B Wi deresay Las, SP2L29 PELE ALE EL. SIMA OT D i> ATUVG 270 Se ~~ prayer) NVYAHID AGAFTIVA ALtYSLOE S GIRVAN DISTRICT aunspuns 0d) KK oN (ested 1 | Va Si (i aie eee : SOUAL AOYPUDS ) Ff SLO OCG NE ELM WAN i > i RESET NINE iM x i 3 bea = a | iS) & SaILaS CUT oo <) | I = we AR a us cwrsrvonong| NEY EL 88 gue sporeey OAM EY NS : hf AIA RK seg nailing TH AW SS BUOISIIUD HP f Lt At v E BL FO ALES 7 a i : See * , | é = NINES S % = | iS Sr San sS 3 ; INR | Ss ~ 8 ss NI Ls She g SSNS Ss S SNE Ss | | 8 as $i 3% BS lis ORS a Less { L Sos dee US SSS eS S = (G g |S BR | Q { . qj SSS 1 NWIMNTIS /NVIDIAOGYQ BS Deeadelll Vol VI.PLIUL. GEOLOGICAL SECTIONS Turoucw rae LoweR Parreozoic ROCKS or THE SouTHeéen UPLANDS oF SCoriano Geol Mag 1889. : ae \ = , < = 3 My * J = ze S £6 a a SITY i) a= ss es Seen a : | : se pu souoepimg + |Ih H bs S1OLBLHO"GD) AVF] FT j Wa CYT MOZLOT B25 x 3 | PDLLOIOGIB = ig Hf GY) ~ | 7 ‘ . = = MIU IT > Hold ye © 4 vg PUTT age WeoPay/ = 2 ¥ ‘GH “if nS FLORID S D7 VIO A i ee 3 = SG Mt tj = ’S dA PIO A ref 2 8 Ma ~ WIOCHTMET ye f UQRWING AT a > Hh { Q FUBIONZ UI) S 5 worry Ii & daa

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Z s SE NS « AS CUO I Wk 3S ~ wy | z iN PPD. € : MALY 2 t He VR BS , = S A y Ay VAS > eo & % 5 SY 8 2 sow 2c phony JS sb10.19 IY PRET Q S Ys } Vice aA ee CLE ie. y S MY HDNADIEY D ’ : ; ; ?, NI = a x “2 Gee \ g ome | Bee Wy 8 . pmerane, BSe 8% wiwlongea : 4 Co Nes: + "ed UPA LEE A Puss Z is afl << nue roy aS 3 % S = hinive «hee = Ne leer S q “Aa Ss y Pies el esie S 9G, S SS 10 LPRMOT FN) N y Bio1g Opy 7) >? So uy WITS EFOT WS SS 2 f GZ, y > | "I rs . * . \ ~ Y- AN 5 R Oe he as SS eg ss & BN lees 8 4 s ~ fe S 4 S 3 AMELIA SS ACLLC / 9 z= SOY, I~ » EQ & dn049 UDI 8 > aS _ | y : ae MS OG (oro + IRS RL S 5 QTY Seragenmydsnty pre 6 wu AS says) epeEs NSF = - - 3 popnenn sey dev : SB ty M9 Dy 7 [dS¢ x c YYRT © oe ¥ by \ - NR ee %S} I RS Se PI ARE 3 gree nll ect (NB SS 5 8 yg \voefwoyy | | S Poe yoounowiy \\% SG 7794149 IKE TS YN ad py NITD 3 “OSTRY LAO Tie 9 S ly Yea\ z Dy A y - | x ee Wek a &. . ee oe NE S > ug wrynotz 7 | G Sos aks > NX \ S ZLPP ANOLD ANS g x wp sbbyyp oe | 5, x op nengeiHTy KS 8 ; > 207, |~S\\ 3 propper eoamie 2 oF Sees M4 AE 5 KG 27 Aap o”g, oe SSE Wi G & br012) 204 ( ~ | } . 9 aK lg . & vy | | W aN NY aN) SS NY 2 s NOLSI/YD ~ we & = lo z FVYLNY TILT N ihe S I) ae: = 5 \ J S FO. = £Q x eas S AiLsoqgsur7)1/) 7) & \ & LLORES, is 3 Sevan si if g 2 ~ y N SS a “8 oan eal i x = LNOL) PIP AD 0 s a © >b § [J INvONOG = N | | : 8 pee ‘ tS OE Geer -2og 7 en cee ey) S S SSH NIZAT a) 8S S OP LMOLY aa ; Eo) 4 S wale Pea 2 Po "@ oy g < : a w 8 Soules WaNgrupay 'z Z| xc LO AELAH NEL K } _ Se t (ia & C8 2 gap spumplay Py’ S § a & S N drag.anmoy oq > SS % $ ao aes < DILL I? 1 Pa N x aa 5 <= N : 4h L007 7VONFT pi R> t 8 Jpsnmrse BEE S renner Re as SS De 1) : S ‘Me7 & SS YO Ses Bede d_ nS y8 < ie aa 3 SOs S714ae ; A sso. JS SS “STVHova] “vem ‘ si TI NIVENId, (.. i {RR : Ss “4 Li as gg =, Sk SAO) yy Se S syoppoumnuanyng y\- Z aie) + t RY sp 70eltoay 31 VE NS auamydeay is iW es DEES : 2 aN) Dib 0p 2) Fae) eR | - Ne Nv wouey eT Nix BIOS WE eR eee ek ny ‘i os ‘ ee & S . > S igo eie beh LO DIYPURS JF SS SER NLEMD, i 8 : 49 DO OIT CO : é 922.02, ~ Pun youu : Q epembnt ed B® S 9 poy siboa og: Ne anRepy eT ae ‘ie NE ae yes spaysniadhng | ii: = WNIT SIIMOD HE aed 7109 X& aucrspuce Il 1} } ques BHevinsiy7 PONCE AS ee Par 0 “oz Mu Le i : Lroay py.) >) ve pete & La (di Bo jl i; a : ; igoohe : SS x i 1g Nhe NUNGO YF J : SOLAS PEATE ay = le ie : Ti SS iS 8 QUPZTIUI | = g < | S 4 Ri N a = PX NSS = F ; ppafjive) 27d PLO b ATUVG 270 Ve iS : 3s ie 3 é t yo = s 2aysy Binguip ey i. x Pre? iS > RE 88 : o, Z S 3 NYAHD IOATTIIVA 5 ioe N S ay aN NYP S21) 2 P20 (RLF & Q 2i1ysihiE s = 2 asl = + WR Si 519; i $ |= at \ : = AXE aly \ & & ny => euqspuns \ sy = = SNS a Se i — [Se ~ a3y 010 YIMOT aunspine yo dy SX NYIUNTIS :NVIDIANCGNO —— tt ‘ Prof. C. Lapworth—Ballantrae Rocks of South Scotland. 61 Moffat Terrane in the Scottish Uplands we find the grand mass of more or less barren flagstones, shales, and greywackés which make up the overlying Gala or Queensberry Terrane. In the Girvan district the rocks belonging to this terrane form the local Dailly series: and are about 2500 feet in thickness, consisting mainly of repetitions of gray grits, flagstones, and red, green and purple shales. The Graptolitic fauna of the terrane is more or less transitional in character. Several forms are certainly peculiar to the Gala beds, but the older zones contain many survivors of the Moffat (Birkhill) fauna, while the higher zones yield several species which recur in the overlying Riccarton (Wenlock) rocks. The strata of the Gala Terrane grow somewhat thicker and coarser as they are followed eastward from Girvan over the Uplands, and fossils become rarer ; but even in the central parts of the plateau (Dumfriesshire and Selkirkshire) a lower (Queensberry) and a higher (Grieston) division ean still be roughly made out. Followed, however, still farther to the south-eastward, the rocks of the terrane soon imitate the example of the underlying Moffat series, becoming much finer in grain and decreasing in thickness. Finally, the whole terrane plunges in this direction (Hawick, etc.) below the Wenlock: rocks of Riccarton and Kirkeudbright, and when it re-emerges in the Lake district, it has dwindled down to an attenuated series of coloured shales and flags (Browgill or Pale Shales) with a collective thickness of less than 300 feet.2 Hven here, however, its strata are still marked by the same two transitional subfaunas as those of the great Gala Group of the Scottish Uplands. : We find, therefore, that while the South Scottish strata of the Moffat Terrane are reduced to nearly a tenth of their original thick- ness within a comparatively short distance (25 to 50 miles) of the Girvan district, the thickness of the massive Gala Terrane remains practically undiminished over most of its visible range in the Scottish Uplands, and is even augmented in the central parts of the plateau. Hence in spite of its greatly inferior systematic importance, the Gala Terrane has a collective thickness over the Upland region far in excess of that of the underlying Moffat series. It follows, as a natural consequence of this fact, that when we regard the Upland region from the structural or tectonic point of view, we find the main mass of its visible rocky floor is formed of the rocks of this great greywacké or Gala terrane. ‘This has been crushed into innumerable wrinkles and puckers; the strata of the underlying Moffat series rising to the surface only along some of the larger anticlinal forms. As in other convoluted regions, the vast majority of these folds are of the class known as overfolds or inverted folds,— the axial plane of each fold being more or less inclined to the horizon; and thus the apparent dip of the truncated strata seen in section gives no clue whatever to the natural succession of the beds. But for many years it has been acknowledged on all hands that these overfolds are broadly related in position to two main struc- 1 Q.J.G.S. 1882, p. 659. 2 Marr and Nicholson, Q.J.G.S, 1888, pp. 674-678, etc. 62 Prof. C. Lapworth—Ballantrae Rocks of South Scotland. tural lines, to which their axial planes strike more or less parallel, along which they are practically perpendicular, and from which, or to which, they slope as we pass outwards in opposite direetions. These neutral lines run longitudinally (but somewhat obliquely) through the Upland region from sea to sea. The southern line sweeps from St. Abb’s Head past Hawick and Dumfries towards the Mull of Galloway, and the northern line from Dunbar through the Lammermuir and Moorfoot Hills, past Lead Hills and Carsphairn to the sea near Port Patrick. From the opposite sides of the Southern (Hawick line) the axial planes of the parallel overfolds slope out- wards to the south-east and north-west, the axes of the two opposed sets of folds having been pushed over in opposite directions upon the neutral line. Along the opposite sides of the northern (Lead Hills) line the axes of the inverted folds usually dip inwards, the axial planes of the two opposed sets of folds sloping obliquely outwards above from off the neutral line. In this second case (Lead Hills line) we have clearly nothing more than the ordinary “fan structure ” of mountain areas. In the first case (Hawick line) we have merely the “fan struc- ture”? inverted. I have discussed elsewhere! the stratigraphic significance of these forms in mountain areas generally, and have shown that we must naturally expect to find the deepest strata in the ‘“‘fan structure” (endocline) or pseudo-synclinal form and the highest in the folds of the inverted fan structure (exoelne) or pseudo-anticlinal. These deductions are strikingly exemplified in the present instance. The whole of the Gala terrane has been swept off-for some miles on both margins of the Lead Hills pseudo-syn- clinal, and the locally thick Moffat terrane, which is there some thousands of feet in vertical extent, has been eroded almost to its base. Along the Hawick pseudo-anticlinal, on the contrary, the rocks of the Moffat terrane are wholly buried from sight, while the Gala terrane is present from base to summit, and subsides to the southward under the still higher group of the Riccarton and Balmae series (the Upland equivalents of the Wenlock and Lower Ludlow strata of Siluria). Roughly parallel with these two neutral lines (or axes of axes), to others less perfectly defined, and also to several gigantic strike- faults, the strata of the Scottish Uplands are ridged up into over- folds of all degrees of importance and complexity, from the crests of which the rocks of the Gala terrane, in many cases, have been removed, and the strata of the underlying Moffat terrane laid bare. The exposures of these pre-Gala strata usually occur in more or less connected areas, in broad boat-like patches, or in narrow dis- connected moniliform lines. These are disposed in broad geogra- phical bands or zones which range longitudinally through the district parallel with the chief axial lines. Three of these bands are especially conspicuous: (1) the 8.E. band of Wigtown, Moffat and Melrose (Moffat-Melrose band), (2) the central band of Port Patrick, Lead Hills and Lammermuirs (Lead Hills—Moorfoot band), and (8) the western zones of Ballantrae and Girvan. Tach of these bands is in 1 Lapworth, Gzon. Mac. 18838, p. 188, etc. Prof. O. Lapworth—Ballantrae Rocks of South Scotland. 68 reality the locus of a complex anticlinal form, whose component simple folds have been crushed together, overthrust, and irregularly denuded. As we pass from the Moffat area to the north-eastward, we find that each of these compound anticlinals increases in length, depth, and systematic importance. In the anticlinal forms of the first band (Moffat-Melrose) the exposures of the strata of the Moffat rocks appear as narrow inliers in the locally ended Gala terrane, — and are at the most a score or two of yards in width; while the total thickness of the pre-Gala rocks exposed (Birkhill to Glenkiln) is only from 300 to 400 feet. In the anticlinal forms of the second band (Lead Hills—Moorfoot) the exposure of the pre-Gala rocks are often more than a mile in diameter; and the strata of the locally thick Moffat Series are occasionally laid bare to a depth of at least two thousand feet, down to the calcareous strata at their base (Duntercleuch and Wrae Hill). Finally, in the most westerly anticlinal forms (those of Ballantrae and Girvan) the exposures of the pre-Gala rocks are four or five miles across; and, as we have seen, not only is the locally massive Moffat series exposed from summit to base (4000 feet), but even the underlying Ballantrae or Arenig rocks are laid bare, as far down as the horizon of the Skiddaw Slates. In the complex synclinal zones, between these complex anticlinal zones, the rocks of the Gala terrane form broader parallel bands sweeping longitudinally through the Uplands from sea to sea. The widest bands are those ranging along the exocline (Hawick line) already described, and those of Gala, Broadlaw, and Queensberry, These bands, however, are all united into a more or less continuous sheet, the Moffat exposures which locally divide them being usually of small longitudinal extent. The Gala beds, on the other hand, which occur north of the main Lead Hills anticlinal (endocline), as at N.W. Peebles, L. Doon, Girvan, ete., are usually disconnected, narrower, and of minor importance. The component formations of the underlying Moffat terrane are frequently well exhibited along the eroded crest of the intermediate anticlinal bands between the more or less continuous sheets of Gala rocks, and their gradual change in thickness, lithology, and paleon- tology can be followed, stage by stage, as we pass from place to place, and from fold to fold. Commencing with the most southerly, or Moffat-Melrose band, we find that in the typical area of the Moffat district we have merely the three Graptolitic zones of the Glenkiln, Hartfell and Birkhill, forming a comparatively homogeneous mass of grey and black shales and mudstones. Followed, however, even along the line of strike to the north-west, towards Selkirk and Melrose, the beds thicken, and bands of grit, flagstone, and conglomerate come in between the shale zones in definite and. recognizable order. But when followed at right angles to the strike from S.H. to N.W. transversely across the Uplands, the change is very much greater. The entire series thickens rapidly, and the black shale bands are replaced one by one from above by barren flagstones and shales, 64 Prof. C. Lapworth—Ballantrae Rocks of South Scotland. similar in all their lithological features to those characteristic of the overlying Gala terrane. Proceeding still farther in this north-westerly direction to the grander anticlinal forms of Carsphairn, Wenlockhead, Moorfoot Hills, ete, we find the Moffat Series represented by a great thickness of grey shales, flagstones, greywackés, and fine conglomerates, with occasional black shale zones (which are most numerous near the base of the series), the whole being intermediate in geographical position, in thickness, in lithological features, and in paleontological characters between the attenuated Moffat Series to the S.H. and the magnificent development of the same terrane in the Girvan region to the N.W. In these intermediate anticlinal forms we can rudely distinguish three main rock-groups, which are, however, so con- voluted and interfolded that their details are as yet only partly worked out, their thickness is unsettled, and their boundaries ill defined. In the cores of the main anticlinal forms of the Lammer- muir-Moorfoot area we find (1) a group of grey and black shales, with flinty bands, grits, and conglomerates (Moorfoot Group), the inner zones of which yield the Graptolites of the Glenkiln Shales, and the outer bands those more characteristic of the Lower Havrifell. Outside this group follows (2) a thick series of more or less barren grey flagstones, shales, grits (Heriot Group), which seems to answer in position and character to the barren beds of the Upper Hartfell. Finally, between these barren shales and the base of the Gala terrane, we recognize a third group (8) (Lugate Group) of grey shales, flagstones, and conglomerate (? Haggis Rocks), with rare fossil-bearing bands, yielding some of the characteristic Graptolites of the Birkhill Shales. In the anticlinal forms of the Lead Hills, Carsphairn and Shinnelhead districts to the south-west, as shown by the published Maps! and Explanations of the Geological Survey, the same geographical and geological grouping is discernible. The local Dalveen and Haggis Rock Group of that region come into the place of the Lugate Series, the Lowther Group apparently into the position of the Heriot Series, while the Leadhills Black Shales correspond in place and fossils with the Moorfoot Series. But as these south-westerly anticlinal forms are of greater diameter, and lie many miles nearer to the Girvan District, there appear, in addition, within the limits of the Leadhills Shale Group, representatives of the lowest Moffat strata of the Girvan area in the form of the Brachiopod- bearing limestones, grits, conglomerates of Wrae Hill, Duntercleuch, and Glendowran.? Finally, when we reach the most distant group of anticlinal forms —those of the Girvan-Ballantrae District itself—the lthological and paleontological modification of the typical Graptolitic Moffat Series is complete, and the terrane is represented by the three rock- formations already referred to, which are as richly varied petro- logically and zoologically as are their equivalents in the well- known districts of Wales and the West of England. ! Compare Maps 15, 9, 3, 4, etc. and the « accompanying Explanations, Geol. Survey, Scotland. * Explan. Sheet 15, p. 14, ete. Prof. C. Lapworth—Ballantrae Rocks of South Scotland. 65 Such I have long held to be the general structure and succession of strata! of the Lower Paleozoic region of the Southern Uplands, as deduced from the facts and conclusions essentially dependent upon the zonal method of stratigraphy. Upon this view the sequence, lithology and paleontology of the several recognizable zones of strata in the Upland region become mutually intelligible, and the various rock-formations and their fossils admit of satis- factory parallelism with those of the corresponding Proterozoic deposits of other districts both in Britain and abroad. See the accompanying table on page 66. It may be objected by some of those geologists who are familiar with the literature of discovery and speculation among these South Scottish rocks, that these views are opposed to those advocated by previous observers.? But I believe that this opposition is more in appearance than reality. The physical facts and phenomena upon which the earlier views of the succession were based remain unquestioned. They are here, however, supplemented by the conclusions drawn from the abundant stratigraphical and paleeon- tological discoveries of the last fifteen years, and have received the only interpretation which seems to me to be possible in the present state of our knowledge. We have to recollect that all the earlier views of the succession were based almost exclusively upon the very natural theory that the Hawick-Dumfries axis is a true anti- clinal form, and the Sanquahar-Moorfoot axis is a true synclinal, propositions upon which no one familiar with our actual knowledge of the stratigraphical phenomena of mountain regions would at the present day place the least reliance; while at the time when the very latest of these earlier schemes was published, the paramount value of the Graptolite as a geological index was unknown and unsuspected. The lithological “groups” of these earlier and local classifications fall naturally into their proper places in the present scheme, and find their simple interpretation as successive geogra- phical bands in the same great Lower Palzozoic succession as it slowly changes in thickness and lithology when followed from the shore line into deeper water: while, under this arrangement, their formerly conflicting Graptolitic faunas show the same sequence they hold over the rest of the Lower Paleozoic world. The present views have also this further recommendation that they depend upon, and necessitate, the harmony of all the ascertainable phenomena— geographical position, thickness, lithology, local sequence, and pale- ontology—and admit of being tested in each of these characters in the field at every stage, and of being confirmed, extended and corrected as discovery progresses. But although I hold that all the known facts and phenomena bearing upon the sequence of the rocks of the Southern Uplands 1 Compare Lapworth, Transactions Geol. Soc. Glasgow, 1878, pp. 78 to 84, etc. 2 Sedgwick, 1849, Rep. Brit. Assoc. p. 103; Nicol. Q.J.G.S, 1850, p. 53; Murchison, ibid. 1851, p. 187; Siluria, 4th edition, pp. 148-158; A. Geikie, Trans. Geol. Soc. Glasgow, 1867, p. 74; Explan. Sheet 3, Geol. Survey Scotland, 1873, pp. 4-18; ibid. sheet 14, p. 9, etc. DECADE III.—VOL. VI.—NO. II. 5 “NVIOIAOGAO “NVIAN TIS ‘ojo “Sine1y sOfLepUElar *2OpeIeD *AIDAOpULylT ‘mouuviey, ASEM IS) ANE)O}OEHES) *solIag IUeIIO A e[epMo110g SOLUS UPS) *dno1iy) JOoj100,, *dnoiy ou0js -oUllT WoystUOD *soTe4S TSTI94S “soleys yeypoyl 'soTeYS Ty eH ‘seregs Tid *dnoixy Joo Fy ‘dnoiy oyesnT *sdnoin s0periey pue ‘u1eydsiesy “US WPA SIFAPPo'T *syooy ovsijueyjeg ‘ANVUUAT, AVUINVIIVE “VW *So1IaS iieg Jo 1eyaury4sg ‘dnoiy) 194] MoT ‘dnoiy yoo ry SISSeTT 2 UsoaAlTeq *solIag UR[[IMpIy “Solleag Spue[Mo\y Iq ANVUUA LT zg IVaddOI “I fq ‘spog [[8mo1g ‘dnoin |Jempiy ‘dnoiy) YOIMe FT ‘dnoiy ejex) "In Artoqsusengd) "soles AyIeq ANVUALT, VIVD ‘DO *yoO[US AA pue MoO[pN'T 1aM0T ‘ojo ‘sse[q pue Sq114) 00}S1U03) ‘dnoiy seujeq *solIoG WOJIVOOIY “MO[pN'T S[PPLIN 73 teddy ‘O40 ‘Sse Too W Aqyisy *purlsug fo 3SO AA “A01U4SIC] OYe'T “spog purpjueg ‘Sped AoseyeUsaT “4q311qpnoyIr yy pue Solipuindg “YsIngxoy 28 YAL[ES ‘040 ‘ollysysinquipy ‘ojo ‘orlrysyieuey ‘oqo ‘omrysihy ANVUUAT, “UNVIINGg ‘CQ “souelioy, T Wav ['Z ON “IA “LOA “JIT Bavouq “NV]T “lomyH ‘AONTNDAG GNVTaQ S$dN0d9 MOOU GNVIdD AHL FO ANANONAS TVURNAOD AHL ONIMOHS GHG NI GOVId VIEL GNY ANYILOOG HLNOG 40 SHOOFY AVULNVIIVG AHL NO UddVg S,HLUOMAVT “OD “oud aLVULSOTTT OL] Prof. C. Lapworth—Ballantrae Rocks of South Scotland. 67 can only be harmonized upon the lines here laid down, it must be frankly admitted that, in spite of all that has been already accom- plished, our knowledge of these strata is still in its infancy. We have so recently become aware of the proper methods of attacking the many geological problems they present for solution, that the most interesting and complicated part of the work yet remains to be done; and those geological students who have made themselves familiar with the new developments of our knowledge of the older rock-formations will find this South Scottish region a fruitful field for original research. My own intermittent labours for the last twenty years in this great plateau (which covers an area of at least 5000 square miles) have been only sufficient to permit of my working out in detail the sequence in the two contracted areas of Moffat and Girvan, and of studying in much less minuteness a sufficiency of the test districts elsewhere to enable me to feel assured of the general truth of the views here developed. It remains for others, and especially for local geologists, to verify and to apply these views to the detailed mapping of the Uplands generally. In the paleontological part of this work the Graptolites must, of necessity, play the chief rdle, for they are almost the only fossils met with in the strata of this wide region. But the minor strati- graphical conclusions to which those fossils point ought not to be overstrained, but should be tested and re-tested upon every available opportunity. We cannot expect to recognize from end to end of the Uplands all the minuter “zones” of Moffat, Girvan, Skellgill or Scania; but we ought certainly to be able to identify by their means all the major stratigraphic subdivisions. Nothing more can be claimed for the Graptolites than that which is claimed by all geologists for the corresponding species of Trilobites or Ammonites. Hach formation has its characteristic Graptolitic species and varieties, and each species has a certain fairly known vertical range in the detailed sequence of the Lower Paleeozoic rocks ;' while the invari- able association of special forms in beds of corresponding systematic position affords a presumptive paleontological index of the true sys- tematic place of strata marked by the same forms elsewhere. With this we must rest content; but even here I hold we have sufficient paleontological criteria, when checked and aided by all the available local stratigraphical evidences, to enable us to map out, in time, the Lower Paleozoic rocks of the Uplands in all their main geological subdivisions. The known restriction of the entire family of the Monograptide to Silurian strata, and its absence from Ordovician rocks, affords us the means of determining the outcrop of the Upland boundary-line between the Ordovician and Silurian deposits; and the laying down of this line will give us the first useful geological map of the region. Next must follow the tracing of the less important divisional lines at the bases of the Glenkiln (Upper Llandeilo) and Hartfell (Caradoc) Groups in the Ordovician, and those at the summits of the Birkhill (Llandovery) and Gala (Tarannon) Series of the Silurian. Not 1 Lapworth, Geol. Dist. Rhabdophora, Tullberg, Skanes Graptolither, etc. 68 Prof. OC. Lapworth—Ballantrae Rocks of South Scotland. until this work has been accomplished, and the Scottish Arenig, Wenlock and Ludlow strata studied in equal detail, can we claim that our knowledge of the geological structure of the Scottish Uplands is even fairly complete. But, if the ideas expressed in this paper are well founded, the main results of future investigations, in so far as they affect the general mapping of the Upland area proper, can even now be sketched in outline. The Axial or Ardwell Group of the earlier investigators will disappear as a separate series, and will take its | place as the southerly extension of the Gala or Queensberry Group to the north. The Dalveen (and Haggis Rock) (Lugate Series) ; the Lowther Group (Heriot), and the Leadhills Black Shale and Caradoc and Carsphairn Group (Moorfoot Series) will all be found to be regional geological complexes of a thickness far inferior to that with which they have hitherto been credited: but, nevertheless, each possessing a high local value, as significant of the local peculiarities and intermediate lithological condition of the Moffat Terrane in the central districts. These three “central” groups, when worked out in detail and restricted to their natural components, will be found to follow each other in the order given above :—the Dalveen-Lugate Group answering to the Birkhill Shales, the Lowther-Heriot Group to the Hartfell (Upper, etc.), while the strata of the Lead- hills-Moorfoot Group must be re-arranged, and will fall, part into the Lower Hartfell (Caradoc), and part into the Glenkiln (Upper Llandeilo) formations. The general geological map of the Uplands will show that the rocky floor of that region is composed of strata ranging almost from the base of the Ordovician up to the summit of the Silurian. The outcrop of the main boundary-line between the strata of the two systems (which is on or about the horizon of the so-called Haggis Rock) will be found to pass obliquely across the region from the north- east margin of the Uplands near Dunbar, over the crest of the Lam- mermuirs, to the south of the Moorfoots, and north of the town of Peebles, over the valley of the Tweed near Neidpath and the Crock, into the valley of the Clyde near Elvanfoot ; and thrown next to the southward by the anticlinal of the upper reaches of the Shinnel, will be found to cross the southern part of the granitic range of the Kells towards the sea-coast south of Portpatrick. To the north and north-east of this guiding line the mass of the strata will be proved to be Ordovician; such Silurian rocks as occur forming outliers parallel with the great boundary fault. To the south-east of the divisional line the mass of the strata must be classed as Silurian; the Ordovician rocks only occurring locally as long lenticular inliers, gradually diminishing in systematic importance as they are followed across the country from north to south, and from west to east. Of the Upland “formations,” the Arenig appears to have the smallest superficial extent, its outcrops being as yet confined to the Ballantrae region (unless indeed some of the so-called Old Red Sand- stone near the boundary-line is of this age): the true Caradoe will be mapped as narrow boat-like sheets along the greater anticlinal (‘69 aSvg 22vf of) [‘souenbag purjdq ay} ut aoxjd m9y} pue puepjoog yyNoS jo syooy ovazjuLTeg oy} uo soded s,yytomdey *d ‘Jorg oyex}snIT} OL] *o40 ‘suggvad Ofte g YIM ‘(90avW “IU, Addy) GNv) SINDZUY ZAMOT “040 ‘s1gn1yIv1g21poub ‘DAJO 7, ‘sapiou “ONLY “AJA 7, YUMA “oqo ‘splaed "4S ‘supyeg ‘CT ‘aajeyS jo speq |‘szzuzyov1g71ponb DINAXY AlTaalyy |"°e-Yaz ‘susooynsf “DAjaf, ‘sapiou -0h49 ‘v44a 7, ‘sug A “On7hy Ayes "040 ‘22087049 peeelae ‘SHLVIS MVaGIuS WNC ‘supyig ‘GC ‘nrengoonjq qq “O99 ‘arta ue sSep ‘soyeys ejdind ~amo7 (x) ct ip B req: > 249 ‘WADLD) snp GvsSoztnD ‘snuni2zj1U1a) 01,9 Y YM 3 | ‘oqo ‘wrevyn Sia |sauoyspnyy Pur syiy sse[i42972 (2) -0j04g ‘vipogossoLD “aNOuy TINA (7) e | WIIM : SIISUOBSIAA “S “snap ‘4Souopy Wy ‘saag ANVOUVG (7) | pue 4q8iaqpnoyiry | |amd ‘ourqssouymng “Ni jo |‘suznuoscad ‘yy Wis ‘Saag NOLIVULS (7) dnouy AUATESNaANG *qOLISIC] UPAIID JO SATUAS ATIUVG 6 Eee endl Ban) 2/2 Sr > Zz | o a ee e ssnjosisazg ‘piuoulys ql 5 | ‘ssa Gain J —: S[Issoy |e | *guojyspues pry 314 PIO Woy spreauMop a|e Suyjenpeis ‘sereqs | pUue sOVIq_MOOVHVNSST | ‘oqo ‘TOSI “N GqgSuqpnoxry "N ‘souymng “N “3zeceT *LOrsisiqg TWUINGD ISTAL “SEINQVTIVAINOD HSILIUG HILAOS -(eexjuey[eg pus ueams) enysify *“roriisig NagISAM -HLAON “‘SLISOdad HSILLOOS HIAOS FHL JO SHdAL TYOOT GHL a0 ‘dNVILOOS JO HLOAOS AHL AO SINGTVAINOG HSIWIYd CUNY NOLLY ‘JI ‘ON “TA “TOA “IT advorq Tl WidVvtl sm00u O1OZOWIVd AAMOT Tauu00 HL XNIMOHS "69g “ANIZVOVIN TYDIDOTOAD ‘NVIOIAOGYO ‘NVIUOTIS Sey TY nicench v3 eRe REET ATES ae nom ‘ be H % ve halk x Y ; ‘ + at ; ie rin 4 i r te t j ? oe 0 j k y fi ee Wine. : : ee or ' pi 4 A . he \! a i : ee 70 Dr. F. H. Hatch—Soda-Felsites in Wicklow. phenomenon must be referred to some peculiarity in the disturbances to which the rocks have been subjected. To explain it, we must go to North Devon, a district, like North Wales and the Ardenne, deeply affected by great lateral pressures operating on the solid rocks. At various points of the coast east of Ilfracombe we find among the slates beds of limestone exhibiting a succession of swellings and constrictions analogous to those already described ; and we see that this disposition is due to the welding together of the adjacent limbs of sigmoid folds under a powerful thrust. The stages of the process are clearly exhibited. After the formation of a series of S-shaped flexures in the ordinary manner (Fig. 1), the direction of the pressure relatively to the bed has 4 ‘ 3 4 changed, and the folds have been pressed upon themselves in the fashion indicated in Figs. 2 and 3. A node corresponds to the attenuated middle limb of a fold, while a ventral segment represents the union of the complementary parts of two adjacent folds. It appears probable that the process indicated is also that by which the varying thickness of the greenstone dykes and the quartzite beds has been brought about. It is also seen in various stages in thin bands of grit in the Ilfracombe district. It is not necessary, however, to suppose that the sharp sigmoid folds must be actually formed as a preliminary stage. A series of slight undula- tions, as in Fig. 4, affected by a shearing motion in the direction shown by the arrows, might equally give rise to the alternate nodes and swellings of Fig. 3. V.—On tHE Occurrence or Sopa-Frensires (KERATOPHYRES) IN Co. Wicktow, IRELAND. By Freperick H. Harcu, Pu.D., F.G.S. (Communicated by permission of the Director-General of the Geological Survey.) N an Appendix to the Explanatory Memoir on Sheets 138 and 139 of the Map of the Geological Survey of Ireland (Dublin, 1888), I have given some notes on the petrographical characters of the igneous rocks of Co. Wicklow. One or two of the facts elicited by an examination of these rocks are sufficiently interesting to deserve a wider circulation. Associated with various types of greenstone, which will form the subject of another communication, there occur in the Lower Paleozoic strata of this district (Bala) numerous beds of felsite. These are Dr. F. H. Hatch—Soda- Felsites in Wicklow. al frequently accompanied by felspathic tuffs; and there is no doubt that they are the product of contemporaneous extrusion during the deposition of the sedimentary rocks in which they occur. Microscopical examination and chemical analysis show that these rocks consist, in part at least, of soda-felsites or keratophyres. The keratophyres (so named from their resemblance to hornstone*) were first described by Giimbel;* but it is to K. A. Lossen® that we are mainly indebted for the investigation of the characters of these peculiar rocks and the vindication of their claim to consideration as a definite rock-type. They are characterized by a remarkably high percentage of felspar, especially of soda-felspar, which in some cases appears to be soda-orthoclase or soda-microcline, in others, albite. In consequence, splinters of the rocks fuse more readily before the blow-pipe than the normal quartz-orthoclase- felsites. Normally constituted felsite, that is to say, rocks composed of a eryptocrystalline aggregate of quartz and felspar (in great part orthoclase), with or without porphyritic quartz, also occur in the Wicklow District;4 but there is little doubt that the two types graduate into one another. Some specimens, collected from a rocky eminence a quarter of a mile west of Brittas Bridge, seven and a half miles west of Rath- drum (Sheet 130), will serve to illustrate the characters of the keratophyres of this district. The rock cropping out at this place is a compact felsite, having, when weathered, a curious mottled appearance, due to the presence of numerous greyish-brown spots of about a quarter of an inch diameter. These spots are crowded closely together, being only separated by a small quantity of a dark grey interstitial substance. Where still more exposed to the action of the weather, the rock is coated with an opaque white crust. When fresh it is of a dark bluish gray to black colour and splinters readily under the hammer. Under the microscope it is seen to be composed almost entirely of felspar and quartz, the former being in excess. The few porphyritic crystals are invariably felspar, the quartz being confined entirely to the ground-mass. The texture of the latter is extremely variable. In general it is microcrystalline, consisting then of square and lath-shaped sections of felspar, between which are entangled irregular grains of quartz; in places, however, the texture sinks almost to cryptocrystalline, the individual granules becoming so small as to be scarcely distinguishable ; but even then, by the use of a higher power, the microcrystalline structure can generally be made out, and there is no evidence of the presence of any ‘‘ micro- felsitic ” (isotropic) matter. Scattered sparingly through the sections are scales of chlorite, 1 Gr. xépas, a horn. 2 Die palaolithischen Eruptivgesteine des Fichtelgebirges, Munich, 1874, p. 45. 3 Zeitsch. deutsch. Geol. Ges. xxxiv. (1882), pp. 199 and 445; xxxv. (1883), p. 215; Jahrb. k. preuss. Geol. Landesanst. fiir 1884 (1885), p. 21. 4 See Explan. Mem. on Sheets 138 and 139 of the Map of the Geol. Survey of Ireland, 1888, p. 0. 72 Dr. F. H. Hatch—Soda-Feisites in Wicklow. and isolated granules of sphene ; occasionally also a few tiny specks of iron-ore. The porphyritic structure is not well defined, there being but little difference in point of size between the “ porphyritic” felspar and the crystals of that mineral in the more evenly crystalline portions of the ground-mass. It is only the occurrence of an isolated large crystal in a eryptocrystalline part that gives the porphyritic appearance. These large felspars form broad rect- angular crystals, which are sometimes slightly rounded. In some cases they present a fine twin-lineation either on one (the albite) or two (albite and pericline) types. In other cases the crystals show no trace of twinning. Such crystals, however, are characterized by another and somewhat remarkable structure. They appear, namely, between crossed Nicols to be divided up into a number of rect- angular patches by narrow partitions, which have an extinction- angle differing slightly from that of the main portion. In other cases the central portion extinguishes uniformly, while a marginal layer goes out at a slightly different angle. The latter case can sometimes be made out without the use of the Nicols; the rim of the felspar-section being clear, while the central portion is speckled over with minute opaque particles, giving it a somewhat cloudy appearance. Have these phenomena, more especially the first- mentioned, anything in common with the “felderweise mikroper- thitische”” structure mentioned by Lossen and Rosenbusch as characteristic for the felspar of the keratophyres? The smaller felspars of the ground-mass are mostly striated. A chemical analysis of this rock gave me the following result :— $10. 500 | 000 = 77°29 IGOR G05) Ss ‘ Fe03 (a trace) be ais Ta62 CaO (a ae 30.000 Bag! do cao, Odd — MgO ... RAED) 3G) \) CORREA EH Bets wk eA y Ee 38 K 50 — "16 Na,0 Lares gc = (oo Loss on ignition ... = iT 100°62 Sp. G. = 2°64 From this analysis. the mineral composition of the rock was calculated to be the followings — JAS) CPUENAWA (465) 440°." sod’ Gageubeea) dos) ona. SS BAD) Orthoclasesi ea) teh ae ce 95 Albite... aH = 64°33 J Felspar... ... o54. 908) 1000 | con) O80 65°28 Other substances .. JA CeIMOAC coo Waodin cae eh As} 100:00 This analysis shows that the rock consists almost entirely of quartz and a soda-felspar (albite). During two visits to Counties Wicklow and Waterford in June and November of last year I collected, among other rocks, a large series of felsites. It is exceedingly probable that a petrographical P. G. Sanford—Analysis of Kentish Rag Stone. 73 examination of these specimens will demonstrate the wide distri- bution of soda-felsites in these districts. Felsites bearing a strong resemblance in age, association and mode of occurrence, to the Irish rocks occur in Wales. We may confidently expect to find keratophyres among them; indeed, Prof. Rosenbusch has already predicted their occurrence among the Welsh rocks.’ They appear also to occur in Arran. An analysis of a felsite from this island by Mr. J. A. Phillips is almost identical as regards the alkalies with the one given above.’ It is interesting to correlate with the facts given above Prof. Haughton’s researches on the Wicklow granites.? As far back as 1859 he showed that in many of these granites there is a dominant soda-felspar; and for these he introduced the name “ soda-granite.” An interesting relation has thus been established between the granites and felsites of Co. Wicklow. What bearing this has upon their mode of origin remains still to be seen. VI.—Aw Anatysis oF THE KuntisH Rae. By P. Geratp Sanrorp, F.1.C., F.C.S., Metallurgical Laboratory, Royal School of Mines, London. N May last I visited the Preston Hill Quarry, near Maidstone, tin the company of the “ Geological Field Class,” conducted by Professor Seeley, F.R.S., and took from it the specimen, the analysis of which is given below. In appearance the rock was a hard, grey, sandstone, containing fine quartz grains disseminated throughout its mass; its sp. gr. = 2°685; on the addition of an acid sulphuretted hydrogen was evolved, from the decomposition of calcium sulphide. The sample contained :— Insoluble Residue ... ... 72°190 per cent = fea ins ALOu= a lo Alumina eee eae ents oo lL ammes =9-068 Ferric Oxide ... doo”) WAI gg = 72°188 Phosphorie acid, P,03. coo OOS gn Lime, CaO. ... soo A os Magnesia, MgO. ... ... 0°054 ,, Alkalies as K.0. aaeih seu OL 22am, Carbonic acid ... sen 9984s. Sulphuric acid, S05. ... 0°647 ,, asinsoluble Ca SOx, no soluble sul- Calcium sulphide, CaSieeee Milessai [ phates. Moisture, at 100°C. ... ... 0°995 ,, 99-917 1 Die Massigen Gesteine, Stuttgart, 1887, p. 418. 2 This MAGazinE, Vol, IX. 1872, p- 540. I give the analysis for comparison :— Siog = 78°32 Al2O3 = 11°39 FeO = Oz CaO SAHIN Sides. ct AOR Re mmmEME bE 13 MgO (a trace SHGRO SAS). ' oceeh pee Rcmrieal ecr _ K, 0 ee 6 seen abo. 20 Na,0 =) G2 H.0 — 1°47 100°80 8 Trans, Roy. Irish Acad. vol. xxiv. (1859), p. 608. 74 Dr. H. J. Johnston-Lavis—Trachyte at Naples. VII.—On a RemarKasBie SoparitE TRACHYTE LATELY DISCOVERED In Napuszs, ITALY. By H. J. Jounston-Lavis, M.D., B.-és-Se., F.G.S., ete. N the last two British Association Reports of the Vesuvian Committee, I drew attention to some very large masses of trachyte traversed, at the back of Naples, by the tunnel of the Cumana Railway. ——_ GEOLOGICAL Society oF LoNnpon. _I.—December 19, 1888.—W. T. Blanford, LL.D., F.R.S., President, in the Chair. The following communications were read :— 1. “ Trigonocrinus, a New Genus of Crinoidea from the ‘ Weisser Jura’ of Bavaria, with Description of New Species, 7. liratus ; Appendix I. Sudden Deviations from Normal Symmetry in Neo- crinoidea; and Appendix II. Marsupites testudinarius, Schl., sp.” By F. A. Bather, Esq., B.A., F.G.S. This genus is proposed on the evidence of two calyces in the British Museum (Natural History), which were found among speci- 88 Reports and Proceedings— mens of Hugeniacrinus from Streitberg. The species of Hugenia- erinus, Phyllocrinus, and Trigonocrinus may be arranged in a series which is apparently one of evolution. The present genus is, there- fore, to be placed with the Hugeniacrinide, although its characters are not those of the family as heretofore defined. This is seen from the following diagnosis :— Trigonocrinus, gen. nov.—Calyx roughly triangular or trilobate in section. Basals 4, but one so atrophied as to be almost invisible ; all fused into a basal ring. First radials 4; the two on either side of the smallest basal half the size of the others, thus maintaining the triangular symmetry; all closely united, with each suture-line in a groove. Processes of radials well developed, forming spines homologous with the petals of Phyllocrinus; excepting the adjacent processes of the smaller radials, which only form a minute ridge. Articular surface of radials curved gently inwards and upwards; muscular impressions indistinct or absent; no articular ridge; no canal-aperture. Arms unknown; ? represented by fleshy appen- dages. Calycal cavity contained in first radials; with small round ventral aperture, surrounded by a rim, which is the only relic of a muscular attachment. Stem unknown. The two calyces belong to the same species, viz. T. liratus, sp. nov.—Calyx rather more elongate than in the known species of Phyllocrinus; basals ornamented with minute granules; radials ornamented with similar granules run into curved ridges, which, owing to their differing intensity, give an imbricated appearance ; spines triangular in section, with the base of the triangle directed inwards, the apex outwards, the angles often rounded. The differentiation of Trigonocrinus from the central Eugeniacrinid type has been effected on the one hand in accordance with the principles of “ Degeneration,” ‘‘ Reversion,” and ‘‘ Use and Disuse”’ ; while, on the other hand, it exemplifies certain methods of change in organic forms, which may be referred to the categories of (1) Sport, (2) Hypertrophy and Atrophy, (3) Fusion and Fission. Thus con- sidered it is of unique interest among Crinoidea. An examination of the variations in symmetry presented by the Echinodermata suggests the conclusion that the Pentamerous type was originally evolved from another system, or at least that it was selected from among other variations, that it has survived, and that it has been kept true, as being the fittest. Appendix I. Sudden deviations from normal symmetry in Neo- crinoidea. A collection of instances from previous authors, with a few addi- tions, the whole illustrating the latter portion of the paper. Appendix II. On Marsupites testudinarius, von Schlotheim, sp. A synonymy of the genus Marsupites; it contains but one known species, and all other names must yield to this one. 2. “On Archeocyathus, Billings, and on other Genera allied thereto, or associated therewith, from the Cambrian Strata of North aoe Spain, Sardinia, and Scotland.” By Dr. G. J. Hinde, Geological Society of London. 89 A revision of the type specimens of the three species included by Mr. Billings in the genus Archcocyathus shows that each of the species represents a distinct genus. Archeocyathus profundus, having been selected by Mr. Billings in 1865 as the typical species, was retained as such, and the characters of the genus, as shown in this species, were defined; Arch. atlanticus, Bill., was made the type of a new genus, Spirocyathus; and the third species, Arch. minga- nensis, which proves to be a siliceous sponge, was included in a new genus, Archeoscyphia. Including the genera allied to Archeocyathus, described by Meek and Bornemann, the following constitute the family ArcHmooyYa- THIN, proposed by this last-named author; Archeocyathus, Bill. ; Ethmophyllum, Meek; Coscinocyathus, Born. ; Anthomorpha, Born. ; Protophareta, Born. ; and Spirocyathus, g.n. The genera of this family are characterized for the most part by turbinate or subcylindrical forms with stout walls enclosing an interior tubular or cup-shaped cavity. Their skeletons are of car- bonate of lime in a minutely granular condition. The walls in the first four of the above-named genera consist of an outer and inner lamina connected by vertical and radial septa; dissepiments are generally present between the septa; save in the genus Anthomorpha, the outer lamina of the wall is regularly and minutely perforate, and the inner lamina and septa are likewise cribriform ; Ethmophyllum is particularly distinguished by oblique canals connecting the interspaces of the wall with the central cavity, Coscinocyathus by transverse, perforate tabule, and Anthomorpha by the apparently imperforate character of the surface lamine and septa. Protophareta and Spirocyathus are either non-septate, or very obscurely septate ; their skeleton consists of anastomosing lamine and fibres ; in the latter genus the lamine are remarkably thickened by successive secondary deposits of calcareous material. The Archzocyathine are regarded as a special family of the -Zoantharia sclerodermata, in some features allied to the group of perforate corals. The family is restricted, so far as is known at present, to the lowest fossiliferous zone of the Cambrian strata, that characterized by the genus Olenella, Hall, and it occurs at Anse-au- loup, Labrador; Troy, New York State; Nevada; in the Sierra Morena, Spain; and in the south-west of the Island of Sardinia. The genus Archgoscyphia, based on Archeocyathus minganensis, Bill., is shown to be a lithistid sponge, and Mipterella, g.n., based on Calathium (?) paradoxicum, Bill., belongs likewise to the same group of sponges. The genera Calathium, Bill., and Trichospongia, Bill., are also undoubted siliceous sponges. These various sponges, which were either included in Archeocyathus by Mr. Billings, or regarded as allied thereto, have no relation whatever to the genus, or to any member of the family in which it is included. They come from a higher geological horizon, the Calciferous formation of the Canadian geologists, which is probably the summit of the Cambrian. They occur in the Mingan Islands and in Newfoundland. Archao- scyphia and Calathium are present in the Durness limestones. 90 Reports and Proceedings— 3. “On the Jersey Brick Clay.” By Dr. Andrew Dunlop, F.G.S. This clay is of a dull yellow colour and somewhat sandy; in places it effervesces with acids; bedding and lamination have been noted. The lower part contains angular stones, usually with their longest diameter parallel to the surface of the underlying rock, and either derived from it or trom some other rock not far distant. The bulk of the rocks consist of granite, diorite, rhyolite, quartz-felsite, etc., but there is an argillaceous shale, locally hardened, which is largely developed over considerable areas. The clay occurs in patches, covering all kinds of rocks, and is spread over the raised beaches ; it seems more abundant on the higher grounds. A similar clay occurs in Normandy and in the other Channel Islands. The author was disposed to regard this clay as probably a fluviatile deposit laid down towards the close of the Glacial Period, when the Channel Islands were at a lower level and united to the main- land. Subsequently he conceived that it might be the result of the decomposition of shale, felspathic porphyry, etc., some sections seeming to show this process as still going on; the clay, too, seems better developed over this class of rock ; if so, it would require a moving force more energetic than ordinary rainwash. II.— Jan. 9, 1889.—H. Woodward, LL.D., F.R.S., Vice-President, in the Chair.—The following communications were read :— 1. “On the Growth of Crystals in Igneous Rocks after their Consolidation.” By Prof. J. W. Judd, F.R.S., F.G.S8. That the characteristic structures of the “ granophyric” rock were not acquired by them during the act of consolidation, but have resulted from secondary changes taking place subsequently, was suggested in a former communication to the Society. Additional evidence was now brought forward concerning the nature of the processes by which these structures — variously known as the micropegmatitic, the centric or ocellar, the pseudospherulitic, the microgranitic, and the drusy or miarolitic—which are found in the peripberal zones and the apophyses of granitic intrusions, must have been produced. That fragments of crystals in detrital rocks undergo enlargement and redevelopment has been shown by Sorby, Van Hise, Bonney, and many other authors. The fact has also been frequently recog- nized that curious outgrowths may often be detected in connection with the crystals of igneous rocks; such outgrowths have usually been regarded, however, as having been formed during the original consolidation of the rock. In a ‘“ labradorite-andesite” (labradorite of French petrographers) belonging to the older or ‘felstone” series of ejections in the Ter- tiary voleano of Mull, large crystals of a plagioclase-felspar, near to labradorite in composition, are found to exhibit large and remark- able outgrowths of very irregular forms. The distinction between these outgrowths and the original crystals is rendered very obvious from the circumstance that the original crystals have been corroded by the enveloping magma and contain enclosures of the same, and Geological Society of London. 91 that they have been much cracked, and sometimes even partially kaolinized before growth recommenced in them. In some cases the crystals have been actually broken and recemented by newly deposited felspar-material. While there is a general crystallographic continuity between the old felspar-crystals and the new outgrowths from them, the varia- tions in the position of extinction in different portions of the enlarged crystal show that, as growth went on, the composition of successively formed zones gradually and progressively changed from near the anorthite limit to close upon the albite limit. These facts prove that, under suitable conditions, felspar-crystals in solid rock-masses may grow at the expense of the unstable glass- magma by which they are surrounded. This conclusion is in com- ‘plete harmony with some other recent researches—especially those of Dr. J. Lehmann on the mode of production of the perthite- structure in felspars. In conclusion, the circumstances which have given rise to the exceptionally clear illustration of the processes described in the rock under consideration were explained, and the bearings of the principles enunciated on the theory of metamorphism are indicated. 2. “The Tertiary Volcanoes of the Western Isles of Scotland.” By Prof. J. W. Judd, F.R.S., ¥.G.S. In his recently published memoir, ‘‘ The History of Volcanic Action during the Tertiary Period in the British Isles,” Dr. A. Geikie, while adopting many of the views propounded in a communication made to this Society in 1874, “On the Ancient Volcanoes of the Highlands,” takes exception to certain of the conclusions which are maintained in that paper. Among the ideas set forth in 1874, of which Dr. Geikie now announces his acceptance, and to which, indeed, he supplies valuable support and confirmation, from his own observations and those of various members of the Geological Survey, are the following :— (1) The perfect transition between the plutonic rocks of the district (granites and gabbros) and the lavas (‘‘felstones” and basalts), and the dependenee of each variety of texture exhibited by them—from the holocrystalline to the vitreous—on the conditions under which solidification took place. (2) The presence of great masses composed of volcanic agglomer- ates, breccias and tuffs, with numerous intrusive bosses, sheets, and dykes, at five well-marked eruptive centres, namely Mull, Ardan- murchan, Rum, Skye, and St. Kilda, and the subaerial character of the ejections at these five centres. (3) The Tertiary age, not only of the lavas, but also of the gabbros and granites found associated with them at these different centres. The conclusions to which exception is taken are as follows :— (1) That the ejection of the “felstone”’ lavas and the intrusion of the granites preceded the appearance of the basalts and gabbros. (2) That the five centres of eruption mark the sites of as many great volcanic cones, now ruined and dissected by denudation. — 92 Reports and Proceedings—Geological Society of London. The view that the acid rocks were, as a whole, older than the basic ones, was originally put forward by Prof. J. D. Forbes and Dr. F. Zirkel, and is supported by the memoir of 1874. Dr. Geikie admits that, around several of the centres indicated, basalts may frequently be seen resting on more acid rocks; but the latter he regards as being, in every case, of an intrusive character; he also allows that the tuffs intercalated with the basalts often contain fragments of felsite, but he does not accept this as a proof that the felsites must have been erupted before the basalts. Much of the divergence of opinion that has arisen appears, however, to be due to the circumstance that Dr. Geikie classes as basalt many of the dark- coloured lavas (augite-andesites, etc.), which were, in the original paper, grouped under the name of “felstones.”” In these “ felstones ” the granites and gabbros alike were shown to be intrusive; and it was also admitted that there were many intrusions of acid rocks of later date than both the ‘felstones” and the basaltic lavas. With respect to the existence of great volcanoes in the district, Dr. Geikie, while confirming most of the statements which were made in 1874 as to the several centres of eruption, prefers to refer the origin of the great plateaux of basaltic lava to “ fissure- eruptions.” He maintains that the numerous basic dykes of the district mark the actual cracks through which the lavas in question rose up and welled out at the surface. In opposition to this view, it was pointed out that the numbers and dimensions of the Tertiary dykes are not such as would warrant us in inferring that they formed the conduits through which the enormous masses of lava forming the plateaux were erupted; and the absence of all proofs of contact-metamorphism at their sides, and of evidence that the majority of them ever reached the surface at all, was commented upon. In 1874 it was pointed out that some of these dykes appeared to mark the radial fissures on which sporadic cones (“‘puys”’) were thrown up, after the great central volcanoes became extinct ; and this view is supported by the circumstance of the close analogies between the materials erupted at this later period, and the rocks which constitute some of the undoubtedly Post- Mesozoic dykes. Dr. Geikie supports his view that the plateau-basalts of the Western Isles of Scotland and of Antrim were formed by “ fissure- eruptions,” by facts which he noticed in the Snake-River country, in the year 1879, while he was making an excursion to the Yellow- stone Park, and also by observations made by Captain Dutton in the Grand Canon country, in Utah, and in New Mexico. With respect to Dr. Geikie’s own observations, it was pointed out that geologists who have had more time and opportunity for the detailed study of the district in question, like Captain Reynolds, Dr. Hayden, and Mr. Clarence King, all agree that there is abundant evidence of ordinary volcanic action having occurred in the Snake- River country ; and the last-mentioned author distinctly points out the great paucity of dykes, and the absence of any evidence of the existence of fissures.such as those from which ‘ fissure-eruptions ” are supposed to have taken place. Correspondence—Mr. C. Davies Sherborn. 93 Captain Dutton, althcugh originally inclined to refer the lava- fields of the Western Territories of the United States to << fissure- eruptions,” has, since his visit to Mauna Loa, and his study of the floods of basalt that have flowed from that volcano, very candidly confessed that, in view of these later observations, he is no longer prepared to maintain his original position. If the effusive action taking place at many volcanoes be rightly understood and appreciated—and the recent very interesting re-’ searches of Prof. J. D. Dana in the Sandwich Islands have thrown much new and important light on this subject—the theory of «« fissure-eruption ” will be found to be as unnecessary as it is vague. At some volcanic centres there is a preponderance of explosive action; at others the main result consists in the extrusion of lava- currents ; while in most cases we find a combination of both kinds of action, The Tertiary volcanoes of Scotland, like the existing voleanoes of Iceland, are interesting as exhibiting evidence of both the effusive and the explosive action on the very grandest scale. CORRESPONDENCE. __ ° UNIFORMITY IN SCIENTIFIC BIBLIOGRAPHY. Sir,—Mr. Davison’s suggestion in the GroLocican MaGazine for January, that the British Association should appoint a committee for securing a uniform and intelligible system of quotation of scientific serials is a very good one. Experience, however, shows us that many compilers, from carelessness or conceit, do not trouble to use those intelligible abbreviations which are employed in Biblio- graphic lists already published, and therefore, not seeing the necessity of making their references clear to those outside their subject, they possibly may not take any notice of another list, even though it receive the authority of the British Association. Mr. Davison proposes a rearrangement of titles of serials, which is decidedly open to very serious objections. The experience of those who have had to deal with large libraries and bibliographic work finds that it is misleading and disadvantageous to alter the plan of the title or use any other than that on the title-page of the volume. If once the rearrangement of titles be permitted, individual idiosyn- _erasies would come into play, and we should have the same serial in two, three, or more disguises. Nor can we take the place of meeting as a guide for library refer- ence; but the systematist must take the place of publication, this being the method at all large libraries and in all the best catalogues. The best plan in making references is to give the title of a serial in the perfect sequence in which it is printed on the title-page of the identical volume referred to, abbreviating the necessary words only, so as to be perfectly intelligible to one unacquainted with the serial, and give the name of the place of meeting in full (or if, as is often the case, no place is mentioned, it is as well to insert it in paren- thesis), add the place of publication at the end of the quotation, and 94 Correspondence—Mr. S. 8S. Buckman. the reference will be complete. This method, followed by all who have dealt with the subject in an extensive and practical way, is found to be the only one that will work satisfactorily. C. Davins SHERBORN. UNIFORMITY IN SCIENTIFIC BIBLIOGRAPHY. Srr,—Concerning the manner of quoting works of reference, I also have to make complaint, namely, that authors sometimes quote, as if it were a complete work, a paper which may be part of some larger publication. Authors, however, are not always to blame in this matter, because it arises from the cause upon which I have another complaint, namely, that some of the Societies who issue Proceedings, ete., often fail to state on the “ Authors’ copies” anything at all concerning the fact that the papers are extracts from their publications. Some of our County Field Clubs are adepts at withholding infor- mation. Sometimes they append no date at all to their publications ; while their authors’ copies suffer, in addition to the omission men- tioned, from absence of date, absence of number of volume, and changed paging. I notice that even the Geological Society omits to give the volume number upon its “ authors’ copies.” I would suggest that the Council of the Geological Society first rectify this matter, and then issue a strongly-worded circular to every Secretary or Hditor of every scientific society in the kingdom drawing attention to these omissions, and stating what is required. Since it is the habit of some booksellers and private individuals to break up odd volumes of Proceedings into their different papers, I would suggest that it is also recommended that these data be printed at the heading of every paper in every volume of Proceedings ; at present such information is lost if one happens to buy the parts of volumes so treated. Date of papers.—I cannot agree with Mr. Davison (Geox. Mac. Dec. III. Vol. VI. No. I. p. 48) that the date of reading be taken as the date of a paper. A new species must date from the time when it is figured, and this cannot happen until the publication of the volume. If authors’ copies be printed in advance, they should be so dated, both themselves and in the volume. 8. S. Buckman. SroneHousE, Jan. 7, 1889. PROFESSOR BLAKE’S ‘‘MONIAN SYSTEM.” Srr,— Professor Blake’s reply to my ‘“ Notes” on his ‘“ Monian System ” requires a few brief comments. Prof. Blake now admits the presence of true schists as derived fragments in the Upper Archean of Anglesey ; but he attempts to neutralize their effect by alleging examples where such fragments occur in the upper part of the formation from which they are derived. He says, “The conglomerate of Bull Bay is made of the underlying quartz rock.” But he has to prove that the quartz rock was not of contemporaneous origin, if the cases are to be parallel. Correspondence—Dr. Callaway. 95. The schist in the Llanfechell Grit is not of volcanic origin tanquam schist ; it must have originated as rock, and been metamorphosed into a schist, before the orit was deposited. The metamorphism must have taken place at some depth, and there must have been a period of denudation previous to the exposure of the schist at the surface. His examples of the conglomerates of Llangefni and some of the Bangor beds are not to the point; since the fragments derived from the associated beds are volcanic, and contemporaneous denudation in volcanic rocks is common enough. That the ‘conglomerate of Moel Tryfaen is largely composed of the immediately preceding Cambrian slates” I dispute. I have seen this conglomerate on Llyn Padarn, and I followed it all along the crest of Mynydd y Cilgwyn, but not a bit of Cambrian slate did I find in it. Dr. Hicks studied it in the intermediate ground of Moel Tryfaen with- out finding slate. I therefore venture to reject all Prof. Blake’s supposed parallel cases, and I call upon him to prove that a true erystalline schist could have been included as a derived fragment in a (roughly) contemporaneous sedimentary formation. As to Llyn Trefwll, I am quite aware that a large part of the ridge close to my sections consists of basic igneous rocks; but as they had no bearing upon my work, I have not referred to them. The rock zn situ, which Prof. Blake now admits is a true slate, on the authority of Prof. Bonney, contains rounded pebbles of the adjacent granite; and Prof. Blake has no right to say either that I mistook diabase for slate, or that I sent. to Prof. Bonney certain derived fragments in mistake for rock in situ. I am sorry the two examples of a supposed passage between the ‘lower and upper groups,’ which I selected because they happened to turn up first, prove to be bad ones. Perhaps Prof. Blake would consider his succession in the northern area more satisfactory. If so, I do not think he will mend matters. He makes the Llanfechell Grit to overlie the schists of Mynydd Mechell; but there is more reason to believe that they are one and the same set of beds in different stages of alteration. Prof, Blake has disappointed me. I asked for particulars of the fauna by whose aid he correlated the Longmyndian with the Bray Head Series, and he refers me to Arenicolites didyma! 1 supposed I must have overlooked some important palzontological discovery ; but no, our familiar little friend turns up in immortal bloom! I respect Arenicolites for its antiquity, but as a time indicator it is worthless. : The “Malvernian” rocks, which I said were included by Prof. Blake in his “ Middle Monian,” are called by him “the granites and altered rocks of Primrose Hill.” I do not think any one who knows the region disputes that these masses are approximately of Malvernian age. Prof. Blake dwells upon the consequences of my acceptance of the igneous origin of the hornblende schists. I stated those consequences unreservedly in my ‘ Notes,” and I do not feel a bit ashamed that I worked on the accepted principles of our science, and was not able x 96 Correspondence—Mr. Alex. Somervail. to penetrate the “dim and distant future.” My descriptions of the older Archean rocks and their distribution are not materially affected by the theory of mechanical metamorphism; but we must of course cease to construct time-series out of them. Alas! how many a stately time-edifice goes down before the blows of those gods of the hammer, Lehmann and Lapworth ! Cu. CaLLaway. THE SERPENTINE OF THE LIZARD. Sm,— Would you kindly allow me to reply to the letter of Prof. Bonney in your January issue on the above subject Hegel y my alleged ‘two slight errors.’ 1. I think the Professor's mind has very naturally (perhaps without reference to the map) reverted to the south end of the Pentreath Beach, where the hornblende schist occurs in conjunction with the serpentine, which he has so ably and minutely described ; but the dyke in question is at the north, or Kynance end, near a large exposure of banded gneissic rocks forming the foreshore of Holestrow, similar to what occurs in many other localities described by the Professor as “granulitic,” as at Caerleon and Kennack, at the west end of which latter Cove the dykes cutting the serpentine are seen to coalesce with the “ granulitic” rocks forming the foreshore. 2. For my own part I know of no “granulitic group” in the whole area with igneous rocks involved or included in it, but a group of rocks to which the term “ granulitic”” might be applied, which every evidence seems to point at as having a common igneous origin, although differing widely from each other; neither do I know any separation between these and the hornblende schists save in the extremes of their compositions, both of which are frequently mingled together in the same dykes. I quite agree and deeply feel with Prof. Bonney the very great difficulties connected with some of these Lizard rocks, such as the explanation of the banded gneissic series which has been so philo- sophically dealt with by Mr. Teall; and it was for this very reason that I ventured my short communication on the dyke and its lessons, in the hope that it might throw some little additional light on these gneissic and other rocks, which I have always regarded as presenting very much that is problematic. ALEX. SOMERVAIL. 59, Frrrt Street, Toravay, Jan. 9th, 1889. MISCHLGLANEHOUS. ———.__—_ AppEnpA.—In the section illustrating Prof. Hughes’ paper, Guot. Mac. Jan. 1889, p. 9, the asterisk indicating the third fossil locality mentioned in the text has been omitted. The spot referred to is immediately under the Bronllwyd Grit, vertically below the Y of that word on the diagram. Decade lll LAVAL AL SBI Vo ol Mag.1882. Ue ( . EC Woodward. del et hth. Dipterus macropterus, Traguanr GEOLOGICAL MAGAZINE. NEW, SERIES! DECADE (fill... VOLE. VIL No. III.—MARCH, 1889. (Quswieuras, Aca NaS tenements. ns Na I.—On a New Specirs or Diprerus. By Dr. R. H. Traquair, F.R.S., F.G.S. (PLATE II.) ROM the Old Red Sandstone of Caithness, four species of Dipterus were originally named by Sedgwick and Murchison,} those being as follows :— 1. Dipterus brachypygopterus, anal fin short. 2. D. macropygopterus, anal fin long. 3. D. Valenciennesit, small in size, narrow in shape. 4. D. macrolepidotus, not characterized although figured. It is evident from the figures of “D. macrolepidotus” that it does not belong to the same genus, even to the same family, as the other forms. Those have circular scales, whereas in “ macrolepi- dotus,” the scales are rhombic, and the head bones are clearly seen to be very different from those of Dipterus. Nevertheless all the four “species” were reunited by Agassiz? into one, for which the name “macrolepidotus” was adopted, in the belief that the rhombic scales of that form were normal for the genus, and that their circular appearance in the others was due to wearing. McCoy, however, correctly recognized the circular contour of the . Scales in the true Dipteri, and rightly refused to recognize “ macro- lepidoius”’ as the type of the genus, or as a Dipterus at all, and in fact proposed to transfer it to Diplopterus.2 The other species proposed by Sedgwick and Murchison he restored to independence. In his “Footprints of the Creator,” Hugh Miller showed that Agassiz’s Polyphractus platycephalus was the head of a Dipterus,* and not a Placoderm, but he did not seek to identify it with any previously described species. Pander ® of course confirmed McCoy’s statement that D. macrolepi- dotus, of Sedgwick and Murchison, was not a Dipterus at all, but he reverts to Agassiz’s idea as regards the three other reputed. species. He united them again into one, for which he preferred the name * Trans. Geol. Soc. 2nd ser. vol. iii. p. 148, tab. 15-17, 1829. ” Recherches Poissons Foss. Tome i. 1835-43, p- 115. * Brit. Pal. Foss. Fase. ili. 1855, pp. 590-592. I have made “ macrolepidotus”’ the type of my new genus Thwrsius, Grou. Mac. November, 1888. 4 1861 Kdition, p. 57. ° Pander (Dr. C. H.) u. d. Ctenodipterinen d. Devonischen Syst. 1858, St. Petersburg, pp. 1-82. DECADE IlI.—VOL. VI.—NO. III. 7 98 Dr. R. H. Traquair—A New Species of Dipterus. Valenciennesii, in order that the honour which the proposers of that name wished to confer on the distinguished French ichthyologist might not thereby be lost. As he also constantly uses the name D. — “nlatycephalus,” it would appear that he considered these large crania also to constitute a distinct species. After a careful examination of a very large number of specimens, including Sedgwick and Murchison’s original types, in the Museum of the Geological Society, I have come to the same conclusion as Pander, namely, that the species, brachypygopterus, macropygopterus, and Valenciennesti are one. In the original type-specimens the apparent difference in the size of the anal fin in the first two reputed species is certainly due to the mode in which the specimens have been crushed, and as to Valenciennesii, I can only recognize in it a young example of the same common species. In the same way the adult condition of this species is to my mind represented by the large heads which have been called “ platycephalus.” If we follow, with absolute strictness, the rules of the British Association in adopting the first of the specific names given by Sedgwick and Murchison, then we shall be compelled to use the very inappropriate one of “ brachypygopterus,” as well as to deprive the name of Valenciennes of the homage which the discoverers of those fishes wished to offer toit. I hope, therefore, that the scientific world will grant an indulgence to Pander’s view, and allow the name Dipterus Valenciennesti to stand for the species in question. D. Valenciennesii is very characteristic of the Lower Old Red Sandstone of Banniskirk and Thurso, but it occurs also in the fish beds of the shores of the Moray Firth, as at Cromarty (Hugh Miller Collection) ; Lethen (Museum of Science and Art); Nairnside near Inverness (Wallace); Tynet (Collection of Rev. Mr. Kyle at Presholm, Banffshire). Another and very distinct species occurs, however, at John O’Groats, where it was discovered by the late Mr. C. W. Peach in the same beds which yielded Tristichopterus alatus, Eg., and Micro- | brachius Dickit (Peach). It is mentioned in Dr. A. Geikie’s list of Old Red Fishes,! and has been very briefly characterized by myself in a recent number of the Grotocican Macazinn, where I proposed for it the name of Dipterus macropterus.? In the present communica- tion I propose to give a somewhat more detailed description of this interesting form, accompanied by the figures on Plate II. Ordinarily at least this species does not seem to have attained any great dimensions, as the specimens in the Hdinburgh Museum average about six inches in length. In general form (Fig. 1) it resembles D. Valenciennes, and the osteology of the head appears to be similar, though I have not found the ctenodont plates preserved in any instance. In Fig. 2 the outlines of the plates of the posterior part of the cranial buckler are given, from which it appears that they are rather shorter and broader than the corresponding plates in D. Valenciennesii, and there is an absence of the small plate which in 1 Trans. Royal Soc. Edin. vol. xxviii. p. 452.. 2 Grou. Maa. for November, 1888. Prof. 0. O. Marsh—Restoration of Brontops. 99 that species is intercalated at the inner angles of the four plates in front of the median occipital. Fig. 3 represents the broad rounded operculum. The scales seem to be very thin, so much so that the internal skeleton is often seen through them, the axis being noto- chordal, and well-developed ribs being present. The leading feature of the species is seen in the form of the second dorsal fin, which has its base proportionally nearly twice as long as in D. Valenciennesit, while the shape of the fin, instead of being triangular-acuminate, is broad and oblong-rounded, the posterior rays being nearly as long as the anterior ones. Bota pectoral and ventral fins are as in D. Valenciennesti “ arehipterygian” in their conformation, the pectoral being represented in Fig. 4. The first dorsal and the anal are narrow-lanceolate, the heterocercal caudal is triangular, and not bifurcated. EXPLANATION OF PLATE II. Fig. 1. Dipterus macropterus, Traquair, natural size. From the Lower Old Red Sandstone, John O’Groats, Caithness. Fig. 2. Outline of posterior cranial plates, from another specimen. Fig. 3. Operculum. Fig. 4. Pectoral fin and shoulder girdle. IJ.—Restoration or Browtors RoBuUsTUS, FROM THE Miocene or AMERICA! By Professor O. C. Marsu, Ph.D., LL.D., F.G.S. (PLATE IV.) HE largest mammals of the American Miocene were the huge Brontotheride, which lived in great numbers on the eastern flanks of the Rocky Mountains, and were entombed in the fresh- water lakes of that region. They were larger than the Dinocerata of the Hocene, and nearly equalled in size the existing Hlephant. They constitute a distinct family of Perissodactyles, and were more nearly allied to the Rhinoceros than to any other living forms. The deposits in which their remains are found have been called by the author the Brontotherium beds. They form a well-marked horizon at the base of the Miocene. These deposits are several hundred feet in thickness, and may be separated into different sub- divisions, each marked by distinct genera or species of these gigantic mammals. The author has made extensive explorations of these Miocene lake-basins, and has secured the remains of several hundred individuals of the Brontotheride, which will be fully described in a monograph, now well advanced towards completion, to be published by the United States Geological Survey. ‘The atlas of sixty litho- graphic plates is already printed, and the author submitted a copy to the Section. The last plate of this volume is devoted to a restora- tion of Brontops robustus, one-seventh natural size, and a diagram enlarged from this plate to natural size was also exhibited.? 1 Abstract of a paper read before Section D of the British Association for the Advancement of Science, at the Bath meeting, Sept. 7th, 1888. % The present Plate (IV.), one twenty-fourth natural size, shows a reduced copy of the same restoration, 100 Prof. O. C. Marsh—Restoration of Brontops. The skeleton represented in this restoration is by far the most complete of any of the group yet discovered. It was found by the author in Dakota, in 1874, and portions of it have been exhumed _at different times since, some of the feet bones having been recovered during the past year. It is a typical example of the family, and shows well the characteristic features of the genus and species which it represents. The most striking feature of the restoration here given, aside from the great size of the animal, is the skull. This is surmounted in front by a pair of massive prominences, or horn-cores, which are situated mainly on the frontal bones. The nasals contribute some- what to their base, in front, and the maxillaries support the outer face. These elevations, or horn-cores, vary much in size and shape in the different genera and species. They are always very small in the females. The general form of the skull and lower jaw is well shown in the figure. The prominent occipital crest, the widely-expanded zygo- matic arches, and the projecting angle of the lower jaw, are all characteristic features. In general shape, the skull resembles that of Brontotherium, but may be readily distinguished from it by the dental formula, which is as follows :— Incisors 2; canines +; premolars ¢ +; molars 3. The presence of four premolars in each ramus of the lower jaw is a distinctive feature in this genus. This character, with the single, well-developed lower incisor, marks both the known species. The number of teeth varies in the different genera. » The form of the teeth, especially in the molar series, is more like \ ‘hat in Chali- cotherium and Diplacodon than in any ‘other known forms. The teeth in the allied genus Brontotherium have already been figured and described by the author. The vertebree are somewhat similar to those of the existing Rhinoceros. In the present genus, Brontops, the neural spines of the dorsal vertebrz are elevated and massive. There are four sacral vertebree in this genus, and in the known species the tail is short and slender, as in the individual here described. The ribs are strong and massive. The sternal bones are com- pressed transversely. The exact form of the first one is not known with certainty, and is here restored from the Rhinoceros. This is the only important point left undetermined in the restoration. The fore limbs are especially robust. The humerus has its tuber- osities and ridges very strongly developed, and the radius and ulna have their axes nearly parallel. There are four well-developed digits in the manus, the first being entirely wanting. The pelvis is very wide and transversely expanded, as in the Hlephant. The femur is long, and has the third trochanter rudi- mentary. The tibia and fibula are quite short. The calcaneum is very long, and the astragalus is grooved above. There are only three digits i in the pes, the first and fifth having entirely disappeared. Diplacodon of the Upper Eocene is clearly an immediate ancestor of the Brontotheride, while Palgosyops and Limnohyus of the Middle ‘ozIs [einjyeu YAnoj-AJUIM} 9UC, ‘pray Ys4ony “wjoyog Jo auasoipy ayy moLf ‘YysiMpT "QC ford Ag pasojsas ‘SaLSOaOx SdOLNOUNg fo wopajays: “6881 ‘OVI “10H “AI “Id “IA “T10A ‘JIJ 2avorq W. M. Hutchings—Altered Igneous Rocks, Tintagel. 101 Kocene are on the more remote ancestral line. The nearest related European form is the Miocene Chalicotherium. No descendants of the Brontotheride are known. Menodus, Megacerops, Brontotherium, Symborodon, Menops, Titanops, and Allops, all belong to the family Brontotheride, and their relation to the genus here described, and to each other, will be fully dis- cussed in the monograph, to which reference has already been made. II].—Norres on Aurerep Jenzous Rocks or TrintaceL, Norra CornWaALL. By W. Maynarp Hurcutnes, Esq. (Continued from page 59.) OMING along the cliffs from Boscastle towards Tintagel, at the part just seawards of the village of Trevalga, and between the outlying rocks known as “Short Island ” and “Long Island,” we see one or two limited outcrops of a schistose rock different from the surrounding slates, shales, etc. A thoroughly good sight of it is not, however, obtained till we reach the extreme north side of Bossiney Cove, a little way south of Long Island, when a very fine exposure of the sheet in question is observed, lying in among the sedimentary rocks, sharply marked off from them at contact, so that the junction- lines can be seen distinctly even from some distance. It dips seawards in the cliff, and a very little way inland it rises to the surface and ends abruptly in an escarpment facing towards Trevalga. To the north, towards Boscastle, the sheet disappears and passes away under the quarries in the cliffs opposite the Growar rock. Going southwards it is not seen anywhere in the cliffs at the back of Bossiney Cove, which has been eroded through it; but at the south side of the Cove a section of it is again seen, similar to the one at the north side, the corresponding inland escarpment, on a larger scale, facing towards the village of Bossiney. The distance across the Cove in a straight line is nearly exactly a mile. Passing through the neck of land which separates Bossiney Cove from the little cove next following it, the sheet is again exposed along the shore, here dipping steeply into the sea. The configura- tion of the land does not here lead to the formation of a prominent escarpment looking inland, but a small outcrop is seen here and there towards the village of Trevena (or Tintagel as it is called). The sheet now disappears ;—the mass of sedimentary rocks in which are the slate-quarries on the church glebe, curving seawards, covers it up in the cliffs, and there is no valley or broken ground to cause an exposure of it inland. It is thus hidden for a distance of rather over a mile and a quarter. Supposing it to be continuous, it is again seen at the north end of Trebarwith Strand, where it rises from beneath the slate-quarries and continues along in one uninter- rupted exposure in the cliffs right away to the south end, a distance of three quarters of a mile. That what is seen at Trebarwith is really a direct continuation of what is seen at Bossiney Cove seems very little open to question. The direction of strike, position with regard to the slates, mode of occurrence, thickness and general 102 W. WW. Hutchings—Altered Igneous Rocks, Tintagel. structure and composition, all appear to affirm it. In the Trebarwith cliffs it is again dipping steeply towards the sea. The upper few _yards of it only are seen, the deeper portions underlying the beach. For a great part of the distance, and indeed wherever the rocks have not been disturbed by falls of cliff and landslips, the contact with the overlying sedimentary rocks is very sharply defined. At the south end of the Strand the sheet disappears under the sedimentary rocks of Dennys Point, and so far as I am aware, it does not show again in the cliffs going southwards; certainly not for some three miles or so examined by me wherever accessible. Whether or not it has any connection with the igneous rocks near Port Isaac I do not know. Near the south end of the Strand a valley, with a road, comes down to the shore. A little way up this road good sections of the entire thickness of the sheet are obtained, near the little village of Trenow and on the opposite side of the valley. It here again forms escarpments in which its upper and lower contacts with shales are sharply defined, and is again cut off abruptly as at Bossiney. We can thus trace this sheet of rock, from north to south, for 34 miles. Its thickness may, on a rough average, vary from 70 to 100 feet. It doubtless originally continued some distance inland. De la Beche speaks of some parts of it (the northern) as connected with rocks several miles away, so that it evidently formed part of a very considerable igneous mass, which was older than any of the rocks already noticed. Considered petrologically this occurrence is very interesting. Macroscopically, the chief observable components are green chloritic minerals and calcite. At some points micas more or less replace the chlorite. Pyrites and magnetite are seen in varying amounts, and at some parts epidote crystals in plenty may be noticed with the naked eye. Foliation is highly developed throughout, always coinciding with the cleavage of the slates and shales above and below. ‘The texture of this foliation varies in every degree, from a fissility almost equal to that of a slate to a series of bands or layers of considerable thickness. Both texture and mineralogical composition vary so much at different points that it would be equally useless either to attempt to give one description that should apply to the whole of the sheet, or to give detailed accounts of all of the series of sections I have ex- amined from different parts. A better general idea will be conveyed by picking out and describing a few of the most strikingly charac- teristic examples. At several places the rock is seen to be very coarsely laminated, layers of comparatively soft chloritic or micaceous material alter- nating with others of a hard, compact, non-foliated stony substance. This is seen most strongly exemplified towards the south part of Trebarwith Strand, where the layers of the stony material are as much as 14 to 2 inches thick in some cases, the softer layers being rather less. A serrated form results from weathering at these parts of the cliffs, the soft layers wasting away and leaving the hard ones projecting. W. MM. Hutchings—Altered Igneous eee Tintagel. 103 Where this coarse lamination is most developed it would almost lead one to believe that it represented an original stratification, or bedding, of different materials; but this impression is much weakened by the fact that this coarsest structure can be traced, in a short distance, passing gradually into finer and finer foliation, and finally into rock in which the chloritic and stony materials are so closely interwoven, so to speak, as to be no longer separable by eye or lens. The material of the hard layers is of a slightly bluish-grey colour. It sometimes contains numerous crystals of magnetite, but beyond this and occasional grains of calcite no separate minerals can be made out with a lens. It effervesces so briskly with acid that this, and its appearance, might easily cause it to be set down as calcite, but its hardness and the fact that fragments do not dissolve, nor even disintegrate, in acid, show that its main component is not calcitic. Portions of contiguous, very coarse, hard and soft layers were sub- mitted to microscopic examination, and a description of them is in- teresting, not simply as bearing on this special form of occurrence, but also because, with slight modifications, a more or less intimate mixture of these two materials makes up a great part of the entire sheet of rock. . The material of the hard layers may be best described by saying that grains of calcite, and grains and more or less imperfect crystals of felspar, are set in what may for convenience be called a sort of “‘ sround-mass ” of felspar, chlorite, small grains of calcite, muscovite flakes, and quartz, with much iron ore. The larger bits of felspar are mostly of quite indefinite and rounded outlines, though a few of them show a certain amount of regular shapes. Some of them show well-developed cleavage, but twinning is so rare as to be practically absent. All are quite water- clear, but are more or less full of minute flakes of muscovite. In the “ground-mass” felspar very much predominates. Its degree of intermixture with the other materials varies, so that at some parts of a slide the whole forms a very fine-grained mosaic, while at others it is much more coarsely compounded. Grains of felspar of ample size to permit of optic tests for its discrimination from quartz are plentifully dispersed throughout. It is all brilliantly water-clear, and no sign is anywhere seen of any definite forms, nor of any twinning. The quartz is wholly secondary, and is rather irregularly dispersed, as single larger grains and as a fine-grained mosaic, either alone or in intermixture with felspar and chlorite. Flakes of muscovite abound throughout the entire mass. Sphene is very plentiful in transparent colourless grains and as rather larger, brownish, less transparent bits; and a good deal of leucoxene is seen in various stages of progress to granular aggregates of sphene. A little rutile is present, mainly in the larger bits of chlorite. Iron ores are diffused in very great abundance all over the sections. Crystals of magnetite predominate, but there is a great deal of rounded, crushed and quite indefinite form down to almost a powdery condition. Among this, small, ragged, flat, thin, plates may be seen, and some thicker tabular bits, but there is nothing 104 W. iM. Hutchings—Altered Igneous Rocks, Tintagel. which could safely be set down as ilmenite, unless it be a few ex- tremely thin flakes, faintly translucent, with brown colour, in some of which sagenitic rutile is visible. ‘These appear to be micaceous ilmenite. It may be as well to remark here that throughout all the sections examined from this sheet of rock, magnetite is the only iron ore which can be specified with certainty. Crystals of it are very abundant, and it is seen that though the greater part of it was formed prior to, or during, the foliation of the rock, much has also been formed since. Much, if not nearly all, of the rounded, flat- tened and totally crushed material is also magnetite; the deforma- tion of crystals under pressure and movement is seen in various stages. Larger plates, with or without leucoxene, which could be classified as ilmenite, are not seen anywhere. Tabular fragments of fair size occur often enough, and leucoxene is present frequently with them; but this, as Mr. Teall points out (British Petrography, p: 167), is not enough to warrant their being set down as ilmenite, because the same result might be equally obtained from titaniferous magnetite in decomposition. The presence in the rock of a notice- able amount of leucoxene, together with the abundance of sphene and rutile, make it probable that ilmenite was originally present in considerable quantity, but is now represented mainly by alteration- products. As bearing on the nature of the original material of this sheet the question as to ilmenite is, of course, of considerable im- portance, and I have looked carefully for any cases of its definite occurrence. The corresponding soft layer does not really differ essentially in nature from the hard layer. The chlorite has increased much in quantity and is in larger pieces. Muscovite also is present in larger amount and in larger flakes and crystals, and also in good-sized patches. Calcite is less in quantity, while quartz again is much increased. Jor the rest, there is the same ground-mass of felspar, chlorite, ete., only that it is not so regularly diffused. There are plenty of large grains of water-clear felspar, and several bits show more or less of twinning. There is a prevalence of very intensely undulous extinctions in the felspars and quartz grains, due to great mechanical stresses. This is more marked here than in any other part of the sheet. The same is true of the minerals of the hard layer, but not in quite so great a degree. The iron ores are very much more in a crushed condition here too. A high power shows the diffusion of minute grains and crystals of rutile all through the sections, together with other grains and microlites which are indeterminable. Microscopic study of these layers, therefore, does not bear out the idea that they are connected with any original bedding of materials of different nature. Much as they now differ in physical condition and general appearance, their constitution is mineralogically the same, and, it is an interesting question as to how this local separation into bands has taken place, and how it is that while the soft layers are highly foliated and split easily into thin pieces, the hard layers have not a trace of such foliation or cleavage. W. M. Hutchings—Altered Igneous Rocks, Tintagel. 105 From the microscopic evidence of great stress in some of the minerals of both layers, it seems safe to conclude that both have been alike subjected to the pressure and movements which caused the foliation of the entire sheet, and that their separation is thus not due to any subsequent causes. And if, as seems reasonable, the passage of these sharply-separated layers into quite close inter- foliation negatives the idea of any prior bedding, it would appear probable that this curious structure was developed concurrently with the ordinary foliation, when the earth-movements took place which have so much affected all the rocks of this district. As before stated, much of the entire sheet of rock consists of the materials of these layers just described, variously intermixed, together with one or two other minerals. At some parts chlorite and calcite increase almost to the exclusion of felspar, at others felspar again plays a more prominent part. Biotite and muscovite vary from total absence to great predominance, and epidote again, which at some parts is very abundant, disappears entirely at others. Large bits of felspar are the exception, most of it being in smaller grains and fine mosaic, and with one exception, nothing at all approaching to original felspar is seen. Specimens from one point along Trebarwith Strand show the presence of a large amount of actinolitic hornblende. It is very pale green, almost colourless, and very slightly dichroic. It occurs with chlorite, into which much of it is in course of alteration. Felspar is in rather largish bits in these sections. A large amount of epidote is present, of yellow colour and rather strong dichroism. It is all in broken crystals and large, detached, irregular fragments, which frequently, at some distance apart, show their former unity. Sections cut across the schistosity of the rock show very plainly that the movements which caused foliation broke and dragged asunder fine large crystals of epidote, and gave an approximately parallel arrangement to a portion of the fragments. This question as to the age of epidote and other minerals, relatively to the foliation of the rock, will be referred to again. In the present instance there is no doubt that epidote crystals were formed in great plenty before the movements took place, and there is no sign of any having been developed since. Hornblende was not seen in any other sections, but would doubt- less prove to be present at other parts of the sheet if more specimens were taken. At a point only a few yards away it had totally disappeared, and epidote was present only in very small amount. Specimens from both sides of Bossiney Cove are interesting owing to the very large development of mica and of epidote. Some of the rock from the south side is made up mostly of biotite, with chlorite and numerous large crystals of epidote. Much of the biotite has a greenish tinge, and is at many points more or less altered to chlorite, much of which appears to have originated in this manner. Most of the biotite is in large irregular flakes, which lie with their flat sides parallel to the schistosity and are drawn out with the chlorite into long, slightly curving lines, But there is also a good 106 W. M. Hutchings—Altered Igneous Rocks, Tintagel. deal of biotite which is not so arranged, but lies with its flat sides in various directions, mostly vertical or highly inclined to the _ foliation. It occurs as very numerous individuals with sharp outlines and boundaries of tabular crystals. It is all quite fresh and more transparent than the other form, and as it has so evidently not been in the least degree affected by the rock-movements, it appears to be younger than the irregular flakes, and to have been developed since the foliation took place. Felspar, some of it twinned, is well represented, and there is quartz as usual. Rutile is very abundant in some parts of sections, as good-sized crystals and grains. The epidote crystals are more numerous and larger than in any other specimens examined. Many may be picked out with a penknife, and their forms examined with a lens, or even with the naked eye; but smaller crystals, not perceptible without the microscope, are also plentiful. These epidotes lie, by far the greater number, with their long axes parallel tothe plane of foliation, lyingin various directions in this plane. Hence slides prepared parallel to foliation show hardly any cross-sec- tions of the crystals, while such sections predominate in slides prepared transversely. Dichroism is moderate, varying from colourless to pale yellow. The crystals are mostly very perfect. The usual elongation in the direction of the orthodiagonal is so strongly developed that the length is mostly very great in proportion to the thickness. The forms do not present anything unusual. The ends are in no cases bounded by definite planes. Cross-sections parallel to the clino- pinacoid, show mostly six-sided forms bounded by the faces 001, 100, and 101, but owing to the disappearance in some crystals of the faces 100, there are also many rhombic sections. Twinning is frequent, both as simple binary twins and as others in which several lamelle are inserted between the two main portions. It is developed not only in the larger crystals, but also in the the smaller microscopic individuals. The occurrence of twinning in small epidotes is stated to be not very frequent. In the sections of rock now under consideration the epidote has not, as a rule, been very much affected by the shearing which has developed a very high degree of “flow ” structure in mica, chlorite, calcite, iron ores, etc. There are many crystals which do not show signs of having suffered any kind of stress or disturbance at all, and which would incline one to believe that they had been formed subsequently to the foliation of the rock. But there are also others which have been broken or bent, some to even an extreme degree, though actual separation of fragments is rare; and a large number of others which have not been so severely affected still show that their internal structure is modified in harmony with the foliation of the other minerals, lines of iron ore continuing their straight or curving courses right through the epidote sections. Also the layers of mica, chlorite, etc., are sharply curved and bent over the angles of the crystals lying in their way. It is clear, therefore, that much of the epidote here was in existence before foliation took place, though there is some of it of which it would not be possible to decide W. M. Hutchings—Altered Igneous Rocks, Tintagel. 107 whether it is subsequent to foliation, or whether it is only that some crystals, for some reason, escaped all sign of stress. Some of the rock from the north side of Bossiney Cove differs from that just described in the fact that it contains a large amount of muscovite, which mineral was absent in the former case. The muscovite here exceeds the biotite in quantity and is, indeed, the main component of the rock. It occurs mainly in small flakes, lying parallel to the plane of foliation, and felted together into compact layers. Sections cut parallel to these layers show many patches in which the muscovite is almost wholly unmixed with other minerals, and which, notwithstanding the presence of many flakes which lie in transverse directions, behave between crossed Nicols as if only one larger individual were present, giving sharp and distinct optic figures in convergent light. In other patches there is more or less intermixture of chlorite, or of biotite-flakes, giving a greenish or yellowish colour and causing blurred and indistinct optic figures. It is in transverse sections that the layers in question are best recognized as being built up of countless muscovite flakes compacted together. Similar occurrences of muscovite take place at several other points in the sheet, but it was not seen anywhere else in such large amount. The biotite of this occurrence resembles in all respects that of the one last described, including the apparent formation of a younger lot of it, but the individuals of the latter are fewer, and are larger and less sharply defined. Felspar is absent in this case; quartz is rather plentiful. There is no rutile in crystals of any size, but under high power the entire rock is seen to be full of very minute crystals and grains of it. Hpidote is almost as plentiful here as in the last instance, and its arrangement in the rock is practically the same, but it is not in quite such large crystals. The sections show that here the epidote has been intensely affected by the rock-movements, not only being broken and dragged asunder, and curved and twisted in all degrees, but being in some cases squeezed into lenticular streaks of crushed material, which is, so far as my observation goes, rare in the case of epidote, and tells of very great siress indeed. So far as these special sections go, there seems no question that all the epidote was formed prior to the foliation of the rock. Lying in among the micaceous and chloritic material at the south side of Bossiney Cove I found an occurrence of rock which deserves special mention, because it differs so very much in many respects from anything else seen in this sheet. It is dark grey in colour, very hard and compact, with quite a splintery fracture. Neither macroscopically, nor microscopically, is there the least sign of any foliation. The part exposed, or at all events seen at any accessible part of the outcrop, was limited to a layer of perhaps a foot anda half in thickness and four to six feet in length, forming a projecting ledge in among the rest of the rock. It made the impression of being part of a thin bed lying more or less parallel with the foliation 108 W.M. Hutchings—Altered Igneous Rocks, Tintagel. of the sheet, but it was not possible to make sure whether this was the case, or to get any idea of its extent. The microscope shows this rock to be made up of much flea with a great deal of chlorite, some secondary quartz, a little calcite, a few flakes of biotite, and large amounts of epidote and of granular sphene. Most of the felspar is water-clear and indefinite, but there are also a good many well-defined columnar forms, of various sizes, showing twinning, binary, and multiple. In the amount of in- dividualized felspar this rock stands out quite distinct from any other specimens from the sheet, as it does also in regard to quantity of felspar present. Many of these felspar crystals are bent and broken and show curved twinning-lines, and a very large proportion of them, as well as of the water-clear bits and the quartz grains show strongly undu- lous extinctions. The epidote also is much broken up and the ends of many crystals are surrounded by quantities of small crushed fragments. But for the absence of foliation, this rock seems to have undergone quite as much stress as any other part of the sheet. Were it not so, one would be rather inclined to think it might be a later igneous matter intruded into the already altered rocks of the sheet. It appears, however, more likely, in view of the similarity of its alteration-products, both in nature and extent, to those of the other specimens examined from various parts of the sheet, that it is really a part of the same original mass, which has escaped foliation for some reason we cannot explain. Were this foliated like the rest, it would differ only from some other specimens in being more fel- spathic; and even this difference might very probably disappear, owing to development of mica and other minerals from the felspar, which there is reason to believe would be brought about during the process of foliation. A thorough study of this interesting sheet of rock would require further attention in the field, and the examination of a much larger series of sections than I have prepared. From what I have adduced above it seems reasonably certain that the entire mass is of igneous origin, but there does not seem to be any basis whatever on which to decide as to whether the original material was a massive rock, consolidated from a molten condition, or whether it was a fragmental deposit of tuff or ash. It seems likely that where such great altera- tions have taken place as are here shown, all clue to the original nature and condition of the rocks would be equally destroyed in either case. Whatever was the original nature of the material, we see from the microscopic record that even prior to the great earth-movements of the district it had undergone very complete alteration under the ordinary influence of chemical action, and doubtless much pressure from the masses of sedimentary rocks piled above it. Secondary hornblende had formed and probably mostly passed in its turn into chlorite. Calcite was everywhere abundant and much quartz had been deposited. Prof. T. G. Bonney—Picrite in Sark. 109 Epidote was plentiful at some parts, as was probably also mica of both kinds, though it is most likely that much of the muscovite now seen was formed at the time when the great crushing and shearing took place. The same may be said of the sphene which is so plenti- ful in nearly all the sections, and which probably originated from leucoxene during the same period, together with much rutile. The great pressure and movement of the mass, we may suppose, also caused the re-generation of the decayed original felspars and the formation of the water-clear material which now plays so large a part in these schists. It can be seen that since the foliation took place some chlorite and quartz, and very large amounts of calcite have been deposited. This later calcite may easily be distinguished in all the sections, and . penetrates the rocks through and through, filling up also all the joints and cracks. At some outcrops it has increased so much in amount that it makes up most of the rock, as in the sides of the valley opposite 'Trenow. TV.—On tHe Occurrence or a Variety or Picritz (ScyELitE) IN SARK. By Pror. T. G. Bonnzy, D.Sc., LL.D., F.R.S., F.G.S. AST summer IJ had the pleasure of passing a fortnight in the Channel Islands under the guidance of my friend the Rev. H. Hill, who has done so much to elucidate their geology. During our short visit to Sark we spent some hours in the beautiful little cove called Port du Moulin, examining the interesting sections of the hornblende-schist and underlying gneissic rocks. J was wandering on the beach looking at the wave-worn boulders which afford most interesting studies of the structure of this crystalline series, when my eye was attracted by one which differed much from the rest, and resembled a dark-coloured serpentine of a slightly exceptional character. With some difficulty, owing to its form, I detached a tolerable specimen, and on examining the fresher surface, felt con- vinced that I had found a rock composed chiefly of an altered olivine and a silvery talc-like mineral. At the time it recalled to my memory in some respects the scyelite described by Prof. Judd, though it did not exhibit the conspicuous porphyritic structure of that rock. The conjecture proves on microscopic examination to be accurate, and I subjoin a short description. Macroscopically the rock exhibits a compact invisible-green or nearly black ground-mass, interrupted by specks and larger grains of a pale-grey mineral with a rather silky or silvery lustre; the grains being interrupted by black spots as is common with bastite. The water-worn surface shows an irregular mottling of black and grey. On using a lens the latter part suggests the presence of two minerals, one having amore fibrous structure and silky lustre; the other a more lamellar structure and more silvery lustre. Some small fakes of a brownish mica can be distinguished, and one or two grains of fair size are distinctly green in colour, resembling 110 Prof. T. G. Bonney—Picrite in Sark. penninite. The specific gravity of the rock is 2°88.' Examined with the microscope the rock is seen to be composed mainly of the following minerals :— 1. Olivine, i in process of conversion into serpentine. The grains, in diameter from about -07” downwards, exhibit the characteristic network structure produced by ‘strings’ of serpentine, often blackened, as usual, with opacite, but give brilliant chromatic polarization in the interstices occupied by the unaltered olivine. 2. A pyroxenic mineral, often in larger grains, most of which is either colourless or of a very pale greenish-grey tint. Evidently more than one variety or species is present. Occasionally the cleavage of a hornblende may be recognized; but much, especially of the greener variety, has an acicular habit, though the needles lie parallel ; thus, though sections be taken at right angles, the characteristic cleavage of hornblende is much more rarely seen than one would expect. These acicular or possibly platy groups often have their divisional planes spotted with opacite and are traversed by thin strings of serpentine. They extinguish simul- taneously and usually at angles below 20°, but occasionally range up to 24°. Moreover, here and there grains occur with augite cleavage or augite extinction, colourless or a very light brown, some of which, with crossing Nicols, have a curious pallid ‘moribund’ aspect. These are commonly surrounded by a felted mass of a fibrous mineral, which gives brilliant tints with the polarizing apparatus. It occurs elsewhere in the slide, and sometimes almost resembles a ground-mass. I regard it as a form of actinolite. On the whole I believe that the original mineral of the rock was augite, perhaps a little variable in composition, and that, as has often been noted in picrites, we now find it in different stages of alteration into varieties of hornblende. 3. A mica-like mineral. Some of this exhibits a distinct though rather weak dichroism, changing from colourless with vibrations perpendicular to the basal plane to pale brown with vibrations parallel with it. Occasionally there is a slight ‘ edging’ of pale dull green. This mineral, when rotated from the positions of extinction (parallel with the cleavage planes), exhibits rather brilliant colours, and the peculiar mottled or ‘shot’ look so common ina mica. The remainder (and greater part) of the mineral is perfectly clear and colourless, and between the crossed Nicols only varies from black to a dull pallid grey or white. Rods or plates of opacite are frequently present between the cleavage planes. I have no doubt that the former is a magnesia-biotite. probably similar to that described by Prof. Judd? in the scyelite of Caithness, and the latter represents an alteration product of the same. I find a rather similar mineral in some of my slides of chlorite schists, and Prof. Judd’s analysis does not differ much from that of a penninite, where the percentage of magnesia is rather low. Certainly a rather large plate in one of my hand-specimens much resembles that mineral. There are also 1 Kindly determined for me by Mr. J. H. Holland in Prof. Judd’s laboratory. 2 Quart. Journ. Geol. Soc., 1888, vol. xli. pp. 401-407. Prof. T. G. Bonney—Picrite in Sark. EEL occasional elongated enclosures, shuttle-shaped in section, like those of calcite figured by Prof. Zirkel.1 These often appear to be composed of a fibrous or lamellar minera] rather similar to the micro- lithic actinolite already mentioned. The larger grains of the mica inclose small grains of olivine, and grains or crystals of this horn- blendic mineral. In some cases needles of actinolite, in length up to about :04”, pierce it obliquely, like pins, making an angle of about ' 35° with the cleavage planes. The penetrating power of acicular hornblende has often been noticed,? so I regard these as probably secondary. In other cases they lie, as above described, between the cleavage planes. 4, Grains of iron oxide (in addition to much scattered opacite and small interstitial plates or rods, especially in the mica). These are no doubt original constituents, but I think that from their peculiar outline they have in some cases received secondary augmentation. Most of these grains are perfectly black and opaque, but occasionally a deep brown tint is just discernible at the edges, and two grains are in parts fairly translucent and of a distinct dull green colour. Hence it is probable that the mineral is chromiferous, and varies from magnetite or chromite to picotite.® One would not be surprised to find some variety of rhombic pyroxene in the rock, but I have failed to identify it, and am disposed to refer all the cleared and colourless mineral to mica, rather than to bastite or bronzite. But this group of rocks is so variable that another investigator may find something which I have not noticed. Some of the grains, I may observe, which I take for altered mica or a chlorite, exhibit a remarkable twin structure—singularly like the lamellar twinning of plagioclase—one set of bands extinguishing parallel or nearly parallel with the cleavage planes, the other at an angle with it which in one case is actually 18°, though generally it is less than 10°. Beyond this it has no resemblance whatever to a felspar. It might possibly be an enstatite, but I think the reference to the mica is more probably correct. I have seen similar twinning, mimicking both the ‘albite’ and ‘pericline’ types in an undoubted altered pyroxenic mineral—probably enstatite—in a serpentine from Carn Sparnack (Lizard), and in other cases. Probably we shall not be wrong in adopting Prof. Judd’s explanation, and referring the structure to molecular strains, which might well be set up in the changes which this mass has undergone. It is evident from the microscopic examination that this rock is very closely allied to the scyelite (altered mica-hornblende picrite) described by Prof. Judd. The published analysis of the latter, as 1 Microscopic Petrography of 40th Parallel, pl. v. fig. 1. * Quart. Journ. Geol. Soc. vol. xxxiii. pp. 910, 913; Teall, British Petrography, - 162. 3 Wadsworth, Lithological Studies, p. 170, etc. * One of my slides from the Rill (Lizard) is full of small crystals of a mineral which I formerly took to be enstatite (altered), but I now see has a very close resem- blance to the bleached mica. ° Loc. cit. pp. 402, 406. 112 Prof. T. G. Bonney—Picrite in Sark. well as the microscopic study, show that the principal minerals occur approximately as follows: Hornblende, 58:5; altered olivine, 22-0; altered mica, 18-5 per cent. JI think that the proportions in the Sark rock are not very different. Hence it is the result of the alteration of a picrite (using the word in the sense in which I have been accustomed to employ it), rather than of a normal peridotite, viz. of a group transitional between the latter and the dolerites.’ So far as we could see this rock does not occur in siti in the cliffs at Port du Moulin, but during both our visits there was a rising tide, and we were not able to reach nearly to low-water mark. Moreover, we found so much of interest in the hornblende-schist and its asso- ciates, that we had no time to search thoroughly the craggy slopes - above. I have, however, little doubt that the rock occurs in siti at no great distance. The boulder—more than half a cubic yard in solid contents—is far too large to have been brought as ballast,? for — it could only have been shipped by means of a crane, and nothing larger than a fishing boat (except in case of a wreck) would be likely to touch at Port du Moulin. Besides, I do not know of any seaport at which such a rock occurs. Since our visit, Mr. Hill has called my attention to the following passage in Ansted’s Geology of the Channel Islands (p. 264): “An important vein of serpentine and steatite, with asbestos and tale, has been traced crossing the central part (of Sark) near Port du Moulin.” This vein, Mr. Hill tells me, he did not find when engaged in the work for his paper on Sark; and as the term ‘ ser- pentine’ was often used rather vaguely at the time when Ansted wrote, he did not attach much importance to it, and the matter had even escaped his memory at the time of our visit. The coast of Sark is very precipitous, and if the dyke is not well exposed, it might easily be missed, even by so careful a worker as my friend. It would now seem probable that Ansted was substantially right in his identification, and that the rock which I have described comes from his ‘ vein.’ As there is no probability of my returning to Sark for years, if ever, I publish this note in the hope that some one will trace this interesting rock to its home. No doubt it will occur as a dyke, and there is a special interest in finding it here, because the hornblende- schist of Sark is lithologically identical with much of that from the Lizard peninsula, where varieties of serpentine are also intrusive in the crystalline series. I may add that, after my return to England, Mr. Hill found a picrite in Alderney, though it is nearer to the olivine-dolerites than that which forms the subject of the present note; this wil! be described in a paper which he is preparing on the geology of that island. Tt is, I think, inconvenient to apply the term picrite both to these rocks and to members of the peridotite group, composed of olivine and augite, where the former mineral dominates. and the percentage of magnesia nearly equals that of silica ; for the latter (probably rarer) form a new name might be coined, if augite-peridotite will not suftice. * Afterwards I noticed two or three others of smaller size. Prof. Prestwich—The Mammoth in the Darent Valley. 113 YV.—On toe Recent Discovery oF THE REMAINS OF THE MamMorH IN THE VALLEY OF THE DaRENT. By Prof. J. Presrwicn, M.A., F.R.S., V.P.G.S., etc. BUNDANT as the remains of the Mammoth and its associated . group of Pleistocene Mammalia are in the adjacent valleys of the Medway and the Cray, none have been yet recorded in the valley of the Darent, to which the Mammoth no doubt commonly resorted at the same time. One reason may be that this valley is very bare of Drift, and between Dartford and Otford there is not a single pit in the little drift-gravel that is met with. Shallow and narrow sections, 3 to 8 feet deep, were, however, opened out in the drift beds last summer for the purpose of the new drainage works for the village of Shoreham. The drift was ‘there found to consist mostly of light-coloured loam, sand and chalk debris, full generally of angular and unworn flints. No organic remains were found in passing through the village, but at its north- west corner, in carrying a trench from the main road down to and under the river, the workmen came, at the depth of 34 feet, upon the tusk of a Mammoth, about 6 feet long, lying in a bed of sand and gravel. It was in an extremely friable condition, and fell to pieces in getting it out. A piece only one foot long reached me. I found. the usual loam, chalk and flint rubble here replaced by a bed of sharp sand and subangular gravel, no doubt of fluviatile origin. I succeeded, by washing some of the materials, in obtaining a few fragments of shells, which I would refer with some doubt to Pisidium, Planorbis and Helix, but they were extremely scarce and friable, and I could not obtain a single entire specimen. The gravel consisted of subangular flints, pebbles of chalk, subangular fragments of chert and ragstone from the Lower Greensand of Sevenoaks, and Tertiary flint pebbles, showing the flow of the river to have been then as now from south to north. SEcTION ACROSS THE VALLEY OF THE DarEenT BY THE PapER-MILL AT SHOREHAM :—DisTance ABbouT 1 MILE. Site of 3 Meenfield Mammoth # D ee all Hill. tusk, Q . 4 VV E =------ Paper Mill. e-- a. Alluvium. 6. Old River-drift. e. Chalk. The height of the spot where the remains were found is 30 feet above the present stream, or 202 feet above Ordnance datum. The earlier works for the main drainage had already shown that the Alluvial beds of clay in the valley were from eight to ten feet thick, with an underlying bed of gravel and chalk rubble five to six feet thick. Therefore the old river at that Quaternary time must have flowed on a bed some 380 to 40 feet higher than at its last stages. DECADE III.—VOL. VI.—NO. III. 8 114 A. Somervail—Altered Hornblende-Schist. Above the village the chalk slopes are entirely bare and without traces of a higher-level river-drift. The foregoing woodcut gives a section of the valley at this spot (see p. 113). No other remains were found here, but at HKynsford, three miles lower down the valley, the foreman informed me that they had found, at about the same depth, but only 20 feet above the river, the entire tooth of a Mammoth. At Green Street Green in the adjacent valley of the Cray remains of the Mammoth, together with those of the Woolly Rhinoceros, Musk Ox, Horse, Ox and Deer, etc., have been met with, and in the associated beds of loam I have found numbers of the small shells of Pupa marginata. VI.—On a Brecora anp an Atrerep Hornpienpe-Scuist at Housen Cove, Lizarp. _ By ALZxANDER SomMERVAIL, Esq. ‘lar rocks forming Housel Bay consist of the normal dark horn- A = blende-schists with the exception of those out of which the charming little Cove bearing the same name has been formed, which © holds nearly the central part of the Bay, facing the south-east. The Cove has three small recesses, an east and a west, and a central one, which receives a small stream flowing into it; the whole, however, a few yards seawards forming one well-defined Cove. On descending into the Cove one is immediately confronted by rocks presenting a very different aspect from the ordinary horn- blende-schists of the adjoining area. A little careful attention on the part of an observer will also lead to the detection of a breccia in the centre of the Cove, close to the stream; the best guide to it being a slickensided surface on which it will be found resting. The breccia is only a few inches in thickness, and is confined to the under surface of the rock overlying the slickenside. It is composed of numerous broken crystals of a greenish-white felspar, varying in size from mere specks up to others of nearly an inch in length, set in a reddish paste formed out of the rock by crushing. It also contains angular and semi-rounded fragments of its own mass, and what looks like small well-rounded pellets of quartz coloured red by the presence of iron. Besides these there is some extraneous like matter possibly introduced or formed during the process of its being cemented together. Altogether its origin is without doubt due to a thrust, or other movement of the one mass of rock over the other with such force as to shatter and groove their Opposing faces. The rock throughout the entire extent of the Cove (which appears to define its limits) weathers into various shades of yellowish-brown and red, and when broken up with the hammer is seen to have a very near approach to a felsite, which it also resembles in composition, being composed principally of felspar and some quartz almost to the exclusion of the hornblende. It also contains scattered throughout its mass some steatitic or serpentinous mineral of greenish colour arranged in (veins and) small concretionary forms. It is, however, evidently only an altered condition of the hornblende-schist, as it con- Dr. C. Ricketits—Changes in the Earth's Crust. 116 tains large eyes of that rock. It can be studied to much advantage — towards the east end of the Cove, where the huge eyes of the horn- blende-schist are distinctly seen gradually to pass into the felsitic rock, which in turn passes into the hornblende-schist at either extremity of the Cove, thus precluding the idea of the former rock being intrusive in the latter. In my short communication! to the Macazine for December last, I referred to the various rocks and minerals formed out of a magma cooling under different conditions, or by its mineral constituents separating during the cooling process. In the present instance we note what seems equally referable to subsequent mechanical and chemical change after the rock had passed into a consolidated state, as attested by the breccia and the highly altered condition of the hornblende-schist. This is but one among the many examples of these Lizard schists passing into each other. Such a passage may also be noted between the hornblende, the mica-diorite, the mica- schist, and other varieties. In the field we catch them, as it were, in the very act of alteration into each other, at least we can observe them in all their transition stages, and these from their decidedly squashed appearance, their frequent lenticular, irregular, and other inconstant characters, betray their dynamic and secondary origin. Still it must, I think, be conceded that however much dynamic metamorphism may have altered these Lizard rocks from their original mineral aspects, every such change in the main has been predetermined by some difference in there primary composition. VII.—On some Puysican Cuancus In THE Hartu’s Crust. (Part II.) By CHaR es Ricxerts, M.D., F.G.S. (Continued from p. 53.) UBTERRANEAN landslips differ from landslips occurring in cliffs along the coast, and in escarpments elsewhere, in that, a fissure having been formed and its sides become separated (Figs. 2 and 38 a), so that they are without support along the line of division, it may happen that by the giving way of some soft or unconsolidated stratum (b), at any depth, from a few feet only, down to the molten nucleus, wedge-shaped masses (c) extending parallel to the fissure 1 On a Remarkable Dyke in the Serpentine of the Lizard. 116 Dr. C. Ricketts—Changes in the Earth's Crust. would break off (d) and slipping down strike against the opposite wall (Fig. 3e) and thus fill up the fissure. An immediate effect of the impulse must be the occurrence of an earthquake shock, more or less intense, according to such various conditions as the size and weight of the falling mass, the space through which it falls or slips, the structure of the rocks involved, and other circumstances. If from a subsequent change this enlarged area is placed in a restricted position, the compression thus caused not only affects to a certain extent the dip of the strata, but causes the ‘fault-rock’ included within the crevice to be compressed into slabs lying parallel to the sides of the fault, forming a coarse but true slaty-cleavage. This cleavage is of very frequent occurrence in the north and south or main faults in the Triassic sandstone of the district around Liverpool. In the Presidential address to the Liverpool Geological Society for the Session 1872—1873' it was explained that the occurrence of earthquakes (not including some connected with volcanic eruptions) was due to the formation of faults, each of which must register at least one, or probably a succession of earthquake shocks. The examination of strata has as yet discovered no other cause than the formation and settling down of geological faults, capable of producing all the varied phenomena recorded as accompanying earthquakes, including that of the huge sea waves, which not infrequently are one of their most destructive accompaniments, when occurring near the coast; being probably caused by the rushing of water into the trough (Fig.3*) formed by the depression of the faulted mass, immedi- ately succeeded by the consequent rebound ; at all events these waves are not due to the shock of the earthquake, for some occurring in the near neighbourhood of the sea, as in that of Hssex (1884), and in North America, at Charleston, §. Carolina (1886), were entirely unaccompanied by such disturbances of the water. The reporter of an excursion along “ the line between the High- lands and the Lowlands,” made in 1875 by the Geological Class of Edinburgh University, under the guidance of Professor Archibald Geikie, noticed the fact that Comrie, celebrated for its earthquake shocks, lies almost directly over the great fault extending across Scotland, 170 miles in a direct line from Stonehaven to the Isle of Arran. He spoke of this as being ‘the first attempt to connect the abundance of tremors at that place with the geological structure of the ground underneath.”* Professor J. Milne, F.R.S., of the Imperial College of Engineering, Tokio, infers “that in Japan faults are still being formed, and that the earthquakes there are to us the announcement of these fractures ;”* “also that certain earthquakes and faults are closely related phenomena, the former being an im- mediate effect of the latter.’* Dr. H. J. Johnston-Lavis, F.G.S.,° and Mr. G. K. Gilbert, of U.S. Geological Survey,® refer the oc- 1 Proc. Liverpool Geological Society. An abstract of this Essay (‘‘ On Fissures, Faults, Contortion and Cleavage,”’ by Charles Ricketts) appeared in the GroLoGicaL Maeaztne, Vol. X. 18738, p. 202. 2 Nature, vol. xii. p. 98. 3 Brit. Assoc, Report, 1881, p. 201. 4 Earthquakes and other Earth Movements, by John Milne, F.G.S , 1886, p. 279. 5 Nature, vol. xxiii, 1881, p. 498. 5 Nature, vol, xxix. 1883, p. 40. Dr. O. Ricketts—Changes in the Earth's Crust. 117 currence of earthquakes to the formation of fissures described as “falling” or “slipping” ; the blow thus occasioned being felt as an earthquake. Fissures and displacements likewise occur as the effect of the shock, in unconsolidated strata or in the banks of rivers; this latter was especially evident in that of Cachar, Hast Indies, in 1869; but instances have been recorded in which an extent of land has at the time of the shock separated and changed its level under such circumstances as are indicative of the formation of these faults having originated and caused the earthquake. Several have been described by Lyell,! and also by others. On two occasions systematic attempts have been unsuccessfully made (by Mr. Robert Mallet after the Neapolitan earthquake of 1857 ;? and by Dr. Oldham with respect to that of Cachar in 1869 ; *) to discover the exact site, the cause of displacements, or the changes which originated the shocks, by tracing back the secondary effects to their source. Though in each case the near neighbourhood whence the shock originated was determined, the exact cause was not discovered. Contortions of strata, even those of great extent, have very generally been attributed to secular cooling of the earth, consequent on its crust being compressed into a less space as it followed the cooling and therefore sinking nucleus. But if subsidence has occurred from such a cause, how is it that, with an increasing loss of caloric, the areas supposed to have been depressed in this manner have been again raised, it may be to a greater height than that which they previously occupied? Sir Charles Lyell remarked that “the wide extent in North America, and in parts of Russia, of Carboniferous, Devonian, and Silurian strata, which, although upraised above the sea, continue almost as level as when the beds were first thrown down beneath the waters, clearly demonstrates the limitation of the agency, to which great foldings and contortions of stratified rocks have been due, to very confined spaces in each epoch ;’* but as these localities are to a great extent situated in regions of excessive cold, in some so intense that the ground is frozen to the depth of many hundred feet, it, I think, likewise follows that, if loss of heat can induce flexures, it must be, as in these instances, to a very limited extent. Mr. T. Mellard Reade, F.G.S., considers “there is a fallacy in the reasoning which attributes the corrugation of the earth’s surface to the contraction of the nucleus” and ‘has arrived at the conviction that the cooling of our earth has not extended to such a depth that we need consider the internal contraction as a geological cause.” ® The Rev. Osmond Fisher, F.G.S8., goes farther; he has calculated 1 Principles of Geology, vol. ii. chap. xxviii.- xxx. 2 Report of the Royal Society of London to investigate the great Neapolitan earthquake of 1857. 3 Memoirs of Geol. Survey of India; vol. xix.; also Quart. Journ. Geol. Soc. vol. xxviii. p. 255. * Quart. Journ. Geol. Soc. vol, vi. p. xlii. 5 Origin of Mountain Ranges, p. 125. 118 Dr. C. Ricketts—Changes in the Earth's Crust. what would be the effects of contraction of the globe in cooling, upon the supposition of the temperature of solidification being respectively 7000° Fahr. and 4000° Fahr. The result arrived at is, that in the former case the contraction of the radius would be six miles, and in the latter two miles only; that the miean heights of the surface-elevation formed by compression would amount in the one to 19 feet and in the other to only two feet;! that is, as I understand him, the mountains caused by this supposed contraction of the earth in cooling might, in one case, be so high as a moderate sized cottage, in the other, as that of a dog-kennel. This being so, well may Mr. Fisher exclaim, ‘‘ Nascuntwr montes, genuit quos ridiculus mus!;’? which may be translated, “The mountains are born, an insignificant mouse is their mother!” This calculation corroborates what has been previously alluded to as to the com- paratively small effect subsidence has in causing lateral pressure or a tendency to cause contortions. ‘Too much, far too much, has been accredited to the effects these movements could produce in causing lateral pressure. Certainly in many instances where there has occurred great disturbance of the strata, by their becoming contorted and folded and dipping various ways, depression to a great extent has also taken place; whereas in others, where it can be proved that there has been at least as great an amount of subsidence, the strata continue as level or nearly so as when first deposited. The difference between the conditions in the different localities is so great, that the contortions cannot be referred to vertical movements common to each. There are other flexures dependent on minor local causes not necessary to be considered at the present time. An important step towards determining the causes of foldings in strata must be to ascertain, so far as is possible, at what period they were produced. Where they exist to the greatest extent, especially in deposits formed of fine mud, cleavage has also been frequently developed, and the particles have so changed their relative position that the embedded fragments of rock lie with their longer diameter obliquely to the stratification, and the flatter sides parallel to the direction of the cleavage; included fossils are distorted, the lower portions being often pressed into their substance, whilst the upper have become elongated ; indicating that the expansion has been from below upwards. Both contortion and cleavage arise from lateral compression ; it is therefore assumed that the same power that has caused the one has at the same time also caused the other. Such changes must have taken place before the original pasty condition of the strata became so consolidated as to prevent, on the application of pressure, movement of the particles of which the mass consists amongst themselves. This might be at any period prior to these clayey rocks becoming solidified by their being raised above the sea level, and the consequent drainage of their contained water, or from other causes. Great power has been exerted in the production of these flexures ; but there is no indication of violence; their state 1 Phil. Mag. Jan. 1888; see also for Nov. 1887. R. Lydekker—A Wealden Celuroid Dinosaur. 119 coincides with a suggestion of Lyell’s, that “they have been the result of intense pressure, so moderated as to be just sufficient to overcome the resistance opposed to it; and that this motion has been as insensible as the unfolding of the petals of a flower.” ? Professor A. Favre of Geneva gives in “ La Nature” illustrations of experiments? in which layers of plastic clay were laid upon a sheet of caoutchouc, stretched one-third more than its length; on being allowed to resume its normal dimensions, the bands of clay were diminished to that extent, and became greatly contorted. The experiments were conceived for the purpose of illustrating the method of formation of the great inequalities on the earth’s surface, such as mountains, etc., by means of lateral thrust or crushing, which are considered by him to be due to the cooling of the earth. They do not appear at all applicable in explaining the cause of eminences and depressions in the contour of the land; they more nearly represent those foldings and contortions of strata which have been universally attributed, since the time of Sir James Hall, to lateral pressure ; but it is too much to conceive that from any con- traction, whether by loss of heat or otherwise, extensive areas have been compressed into a third less than their original dimensions ; as this is a condition of by no means infrequent occurrence in geological formations, the cause of the compression and consequent foldings of strata must be searched for in other directions. (To be continued.) VIII.—On a Ca@iuror Dinosaur FrRoM THE WEALDEN. By R. Lyprexxer, B.A., F.G.S., ete. ie going through the remains of Chelonia preserved in the British Museum I came across two vertebrae from the Wealden of the Isle of Wight, which had been inadvertently included in that series. These specimens (B.M. No. R. 901) formed part of the collection of the late Rev. Mr. Fox, and clearly indicate a small Dinosaur allied to the genus Celurus. Both specimens belong to the cervical region, and are precisely similar; but whereas one is almost entire, the other has lost nearly the whole of the neural arch. The former specimen is_repre- sented of two-thirds the natural size in the accompanying woodcut ; from which it will be seen that it is practically entire, with the exception of the loss of the greater part of the ribs (see p. 120). The chief characters of this specimen may be summarized as follows. The vertebra is considerably elongated, with a markedly opisthoccelous centrum, of which the terminal faces are oblique. The arch is comparatively low, with only a slight ridge to represent the neural spine. The ribs were anchylosed to the arch and centrum, and (from the contour of the basal portion) were evidently much bowed outwards. The sides of the centrum exhibit a pneu- 1 Quart. Journ. Geol. Soc. vol. vi. p. lxiii. 2 They are copied in ‘‘ Nature,’’ vol. xix. December 5, 1878, p. 103. The Rev. Osmond Fisher has reproduced one in “ Physics of the Earth’s Crust,” p. 128, but does not coincide with the deduction Prof. Favre draws from the experiments. 120 k. Lydekker—A Wealden Celuroid Dinosaur. matic foramen, and a fracture across the centrum of the imperfect specimen shows that the inner structure was completely honey- combed. The length of the centrum is 1:74 inches. Anterior and left lateral aspects of a cervical vertebra of Calamospondylus Foxi ; from the Wealden of the Isle of Wight, 3 nat. size; prz. prezygapophysis ; ptz. postzygapophysis; 7, rib (restored); f. pneumatic foramen; s. neural spine. These features show that the reptile to which these vertebre belonged was closely allied to the genus Coluwrus, Marsh;? and it remains to indicate in what manner the two forms differ. Now, in the American C. fragilis, and also in C. Daviesi? of the English Wealden, the cervicals were longer than the present specimen, and while the anterior ones were opisthoccelous, the others were amphi- ceelous.* Again, the vertebree of Coelurus have the arch placed more forwardly on the centrum, so that the prezygapophyses project more in advance of the terminal ball of the latter; while the free posterior border of the rib is extended backwards to join the postzygapophysis, and thus forms a kind of penthouse over the side of the centrum. This penthouse seems, moreover, to cause a flattening of the lateral and upper surface of the arch, which is quite wanting in the present specimens; while the ridge representing the neural spine is much more elongated antero-posteriorly in Celurus. Other minor differences can be seen by comparing the woodcut with the figures given by Prof. Marsh; but the above features are sufficient to indicate that the present form cannot be included in Celurus, if we use generic terms in the sense in which they have been generally accepted in the Theropoda, but that it clearly indicates a member of the same family. Now, putting aside the specimen on which the genus T’hecospon- dylus was based as being too imperfect to admit at present of any interpretation of its affinity ;* the only other genus which appears to have been hitherto referred to the Celuride is Tanystropheus of the Trias, which Prof. Cope considers to be allied to Celurus. In the absence of figures of the American forms referred by Prof. Cope to Tanystropheus, an exact comparison cannot be instituted between 1 Amer. Journ, Sci. ser. 3, vol. xxi, p. 341, pl. x. (1881). 2 See Lydekker, Cat. Foss. Rept. and Amphib Brit. Mus, pt. i. p. 156 (1888). 3 In the definition of the Celuride on p. 155 of the work last cited, the words in anterior region are omitted before the word opisthoccelous. 4 Prof. Seeley has proposed to refer Cel/urus Daviesi to this genus. A. H. Foord—Ascoceras Murchisoni, Barr. 121 its cervicals and the present specimens; but a marked distinction is evident by the amphiccelous character of the former. There is, however, in the Wealden the genus Aristosuchus, which appears to be allied in some respects to Celurus, and of which the type may be taken to be the sacrum.!' Now the present specimens are much too large for that sacrum, and therefore clearly indicate a distinct species; while if the dorsal vertebra” referred to Aristosuchus be rightly associated, we have evidence not only of the generic, but also of the family distinction of the present form from the latter. Seeing, therefore, that we have evidence of the generic distinction of this form from Celurus and Tanystropheus, and also of its certain specific and probable generic distinction from Aristosuchus, I have ventured provisionally to regard it as the type of a new genus and species under the name of Calamospondylus Foxit. This genus being characterized by the opisthoccelous character of such of the cervical vertebre as are known, and by the much shorter length of these vertebrze as compared with those of Celurus. TX.—Nore on tHE Dectpuous Sepra or Ascoceras Murcutsonz, BARRANDE. By Arruur H. Foorp, F.G.S. N interesting paper has lately been contributed to this Macazinz (December, 1888, p. 532), by Dr. Gustav Lindstrém, of Stock- holm, in which he announced his discovery of the earlier, or Nautilus- stage, as he termed it, in several specimens of Ascoceras from the Silurian of the Island of Gothland. I find, however, in looking over the supplementary volume of the Syst. Sil. du centre de la Boheme,? that Dr. Lindstrém’s discovery has been anticipated by M. Barrande, ' who observed and described two of the normal chambers (Nautilus- stage, of Lindstrom) attached to a specimen of Ascoceras Murchisont from the Silurian strata (Htage E) of Karlstein in Bohemia. I give here a translation of Barrande’s description, together with exact copies of the figures accompanying it, and the explanations of the same. A copy of Dr. Lindstrém’s figure is also added for compari- son with Barrande’s. “We have always assumed, especially in the original description of the genus Ascoceras,* that there existed below the body-chamber a series of deciduous air-chambers which became successively detached from the shell by normal truncation. This supposition is confirmed by the specimen which we figure on plate 491. It is quite apparent that fig. 3 on this plate [see p. 122. Fig. 1] represents a specimen which is distinguished from all those before figured upon our plate 95, by the relative length of the septate part which remains attached to the body-chamber. This septate part, when examined, 1 Lydekker, op. cit. p. 158. R. 178. 2 Ibid. R. 178, a. 3 Vol. ii. pt. i. 1877, Supplém. et Série tardive, p. 98, plate eccexci. figs. 3-7. 4 Ascoceras prototype des Nautilides, Bull. Soc. géol. de France, tome xii. p. 157, 1855. 122 A. H. Foord—Ascoceras Murchisoni, Barr. shows distinctly two air-chambers of very unequal height, and bounded by three superposed septa, in the following order :— “1. Terminal septum of the body-chamber, as seen in other ~examples of Ascoceras. «2. Septum placed below the preceding, at a distance of about 7 mm. from the body-chamber. A like distance has never been observed in any other specimen in which two septa could be recognized below the body-chamber. “3. Terminal septum, situated about 2 mm. below the preceding one, and constituting the abrupt truncation characteristic of the posterior extremity of Ascoceras. “This truncated end is very distinct and has a smooth surface. The edge of the test is seen around its external border, and from Fig. 1. Lateral view of Ascoceras Murchisoni, Barr., showing the body-chamber nearly complete, excepting the margin of the aperture. The lower part presents a longitudinal section, showing three very unequally spaced septa, abruptly truncated below. Fig. 2. Transverse section of the same specimen, following the line a—d (Fig. 1). Fig. 3. Lower extremity of the same specimen, enlarged twice, to show more clearly the three septa. Fig. 4. Surface of terminal septum (pan coupé) of the same specimen ; bordered by the edge of the test, which is here broken by natural truncation.! Fig. 5. Ascoceras, after Lindstrém. 1 Fig 7 of Barrande’s plate, an enlargement of the ornaments of the test, is omitted, as unnecessary for the present purpose. this border the test spreads over the external surface of the fossil, and exhibits the ornamentation characteristic of this species, con- sisting of a net-work of fine striae. “The phenomena just described clearly prove that, in Ascoceras, Notice of Memoirs.—J. C. Moberg—The Lias of Scania. 123. as in various genera of Nautiloid shells, the earlier part of the shell. was composed of a series of air-chambers, and that these chambers were periodically thrown off by natural truncation. “Judging by the form of the lower part of the specimen under discussion, it may be presumed that the series of deciduous septa was considerably elongated, and that truncation took place at successive periods. “The length of the specimen described is 48 mm., and its greatest breadth 18 mm. ‘ ; : “This very instructive fossil was found at Karlstein, together with numerous examples of the same species, in the limestones of band e2. It may be added that this specimen has been in our possession for many years, but it was not until the spring of 1875 that we - decided to have a longitudinal section made at its posterior extremity [see Fig. 1], which resulted in the discovery of three unequally spaced septa.” é Although, as we have seen, Barrande was the first to observe and to describe the deciduous septa of te ieee S35] Felsites god? Ee Bo pam Granite and é alion f a dist Metcunorphosed Skiddaw Slates. Seale of Miles ° 5 10 —A + It is a question which has frequently been asked, and the answers given are various. In the present communication I intend to look at it from a somewhat different point of view from that in which it has usually been approached, though the view here adopted in many respects resembles that taken by the late Mr. Hopkins. The exact On the Physical History of the English Lake District, by the Rev. J. C. Ward. Grou. Maa. Dec. II. Vol. VI. p. 58. 2 On the Elevation and Denudation of the District of the Lakes of Cumberland and Westmoreland, Q. J. G. S. vol. iv. p. 70. J. E. Marr—Drainage of the English Lakes. 151 influence which the faults have had in determining the trend of the major valleys is however of little importance to my present inquiry. § 1.—Structure of the District. The well-known general structure of the district is seen in the sketch-map, which exhibits the Lower Paleozoic rocks nearly surrounded on every side by a girdle of Carboniferous Limestone, the strike of which is always approximately parallel to the line of demarcation between the older and newer rocks, the former rising up as an irregular dome within the latter. Whereas the main axis of the older rocks within the district runs through the Skiddaw group of hills, the present watershed is marked by an east and west line running through the Scawfell group across Kirkstone, and the passes at the heads of the Kentmere and Long Sleddale valleys to Shap Wells, whence it is continued in an easterly direction over ground occupied by Carboniferous rocks, separating the head-waters of the rivers Eden and Lune. § 2.—Condition of the area at the commencement of Carboniferous times. Mr. Hopkins pointed out that the dip of the Carboniferous rocks was everywhere sufficient to carry them far above the present surface of the older rocks in the central part of the district, and he gives cogent reasons for supposing that they actually did so extend. As it is of the utmost importance that this point should be definitely settled, I propose here to give further arguments in favour of the submergence of the whole of the Lower Paleozoic area during Carboniferous times, and to show that the present drainage was certainly not impressed upon the district in pre-Carboniferous days. The very uniform plain of denudation upon which the Carboniferous rocks were laid down in the Ingleborough region is well known, but those who maintain the existence of a pre-Carboniferous ridge over the area of the present Lake District require the cessation of this plain towards the west. But MM. de Koninck and Lohest' show that the Lower Carboniferous beds of Belgium are represented by the conglomerate of the Ingleborough district, and it is probable that beds quite as low occur in the immediate proximity of the Lake District, though this point will be definitely settled when Mr. H. J. Garwood, B.A., who is now engaged in a detailed examination of the Carbonifeous zones of the region has published his researches. If the Lake District area had stood out as an elevation at this period, the equivalents of the lowest strata of Ingleborough should he absent here. Not only does the Mountain Limestone form a nearly complete ring round the lakes, but at one point where the ring is broken by the complex group of faults uniting the Craven and Pennine fractures, great masses of the limestone are let down into the dome, as at Grey Rigg and Kendal, indicating that the limestone at any rate extended thus far. Again, the folding of the Lower Paleozoic rocks would not give 1 Notice sur le Parellélisme entre le calcaire Carbonifére du nord-ouest de lAngleterre et celui de la Belgique, Bulletins de ]’Académie royale de Belgique, 3me. série, t. xi. no. 6. 152 J. EH. Marr—Drainage of the English Lakes. rise to a ridge along the present line of watershed of the Lake District, but along the centre of the anticline, though there may have been higher ridges of older rock existing to the north of the 'Skiddaw axis, which determined the trend of the pre-Carboniferous valleys, and that this was the case is indicated by an examination of the mode of occurrence of the irregular patches of the basal Carboniferous conglomerate, and a study of their included pebbles. These conglomerates, from their extremely local distribution, are generally and probably rightly supposed to have been deposited in the troughs of inequalities, though there is some doubt as to the region from which the material was brought. Mr. Clifton Ward, in the paper cited, comments upon the close similarity between the pebbles of the Mell Fell conglomerate to the rocks forming the Ludlow beds of the Kendal district, and the great rarity of local rocks in the conglomerate. I have recently detected a pebble in the same conglomerate at Roman Fell near Appleby, containing a fossil which appears to be Rhynchonella nucula, a characteristic Ludlow form. But, that these pebbles came from the south is unlikely for the reason to be noted immediately, and similar rocks occur in the southern uplands of Scotland on the south side of what probably constituted a pre-Carboniferous mountain axis, so that the drainage may well have come from this direction. Prof. Hughes has detected in the same conglomerates in the Lune Valley, pebbles of the well-known Keisley limestone of Appleby, a peculiar and easily recognizable rock, which is developed in this form in no other part of the district, and which, for reasons which cannot be here given, is unlikely to occur elsewhere. This discovery indicates a drainage on the pre-Carboniferous slopes in a southerly direction, and suggests a northern source for the pebbles of the conglomerate. Now Keisley is separated from the Lune Valley by a continuation of the main watershed of the Lake District, so that at the time of the formation of the conglomerate, if the pebbles of the Lune Valley have actually come from Keisley, the present watershed did not exist, and indeed the way in which the Carboniferous rocks rise from Tebay to Shap Wells, and then sink to the Eden Valley, proves that this elevation was post-Carboniferous. Recent discoveries, it will be seen, fully confirm Mr. Hopkins’s conclusion that the Carboniferous rocks were laid down over the area of the present Lake District upon an even horizontal surface. § 3.—Post-Carboniferous Changes. Formation of the Dome, and Determination of the Drainage. The examination of the area has shown, what would be a priori expected, that the pre-Carboniferous drainage was not determined by the more modern Lower Paleozoic rocks of the district, and these could be converted into the highest ground of the region by no other means than a further upthrust, which took place in post- Carboniferous times. Even then, the drainage would not radiate from an area of Lower Paleozoic rocks, unless these rose above the surrounding high ground caused by the accumulation of the up- J. E. Warr—Drainage of the English iakes, Kad. heaved newer sediments, and the thickness of the latter in the immediate proximity to the centre of the district forbids the sup- position that a high mountain tract over which Carboniferous rocks were never deposited arose in that centre. If we prolong the Carboniferous rocks over the present area in accordance with their various dips at the margins, we shall find that the centre of the dome composed of these rochs would coincide with the small tract from which the principal valleys radiate, viz. the region of Scawfell and Gable. The appearance of the eight principal valleys extending from this point, like the spokes of a wheel, is beautifully described by Words- worth.! They are Windermere, Coniston, Duddon, Eskdale, Wast- dale, Ennerdale, the Vale of the Cocker, and Borrowdale. Further to the east the symmetry of the dome is destroyed by its pro- -longation in an easterly direction as an anticlinal (though even here the Carboniferous beds dip eastward on the summit of the anticlinal axis, showing that the district does not merely comprise the end of an anticline), and by the proximity of the great faults of the Lune Valley. Here, also, the radial character of the valleys is noticeable. To the north of the axis are the vales of Thirlmere, Ulleswater, and Haweswater, and to the south, those of Kentmere, Long Sleddale, Crookdale, Bannisdale, and Wastdale. This radial arrangement is well exhibited in the case of the valleys containing the larger lakes, on examining the small map. The valleys do not in all cases coincide with the observed or theoretical faults shown by Mr. Hopkins upon his map, though the general direction is the same. The radiating disposition of the vales could not have been deter- mined except by a somewhat regular dome-shaped upheaval of the country, and the trend of the Lower Paleozoic rocks shows no tendency towards the formation of a dome in them before the deposition of the Carboniferous rocks, whereas, as has been above noted, the dips of the Carboniferous rocks do point to the pro- duction of a post-Carboniferous dome, whose centre coincides with the point from which the valleys diverge. The drainage system is, in fact, strikingly similar to that represented by Mr. Gilbert in the case of the Ellsworth Arch,? even to the slight irregularity which occurs at the north end of the latter, owing to the proximity of Mounts Holmes and Hillers, and at the east end of the Lake District owing to the anticline separating the Lune and Eden Valleys, and the faults of the Lune Valley. It is hard to resist the conclusion that in the Lake District, as in the Henry Mountains, we have a case of superimposed drainage, the valleys having had their direction determined by the slopes caused by the upheaval of the Carboniferous and possibly of newer rocks, though they now run in the centre of the district entirely through Lower Paleozoic rocks, the newer rocks which were the cause of their present trends having been completely removed by denudation. This seems to me the strongest argument in favour of the former ' A Complete Guide to the Lakes, third edition, page 111. * Geology of the Henry Mountains, p. 139, fig. 71. 154 J. E. Marr—Drainage of the English Lakes. extension of the Carboniferous rocks over the district, and the study of the valley-systems of other areas will probably enable us in many cases to argue concerning the former extension of beds over regions from which they have long since disappeared. The duration of the movement which caused the elevation of the dome is hard to determine. There is no doubt that elevation had taken place before the deposition of the New Red Sandstone deposits of Edenside and the Cumbrian coast, for the latter rest unconform- ably upon the Lower Paleozoic rocks in places, and the former contain fragments of Mountain Limestone, whilst the sandstones were probably derived in great part from the deuudation of the Carboni- ferous sandstones. In connexion with this point the rarity or absence of Lower Paleozoic pebbles in the New Red breccias of Edenside is noticeable, and has been commented upon by Mr. Goodchild.’ It furnishes another argument in favour of the extension of the Carboniferous rocks over the central part of the district. But that the elevation was entirely carried on during the time that elapsed between Carboniferous and New Red Sandstone times is negatived by the dip of the New Red itself, which, as observed by Mr. Hopkins and Mr. Goodchild, is sufficient to carry these deposits also over the central dome. Now, the north-east portion of the Lake District dome coincides with the western margin of the New Red basin of Edenside, and was therefore partly determined simultaneously with the latter. The New Red Sandstones were apparently deposited in a fjord- like indentation produced during the deposition of these rocks (a point which is well worth working out in detail by any one who has carefully studied the characters and distribution of these rocks). But there appears to be no important physical break between the New Red deposits of Edenside and the lowest Jurassic beds of Carlisle. The position of the latter indicates that they also were deposited during the continuance of the formation of the basin, and there is no reason why these and newer Mesozoic rocks should not have once extended over the gradually rising dome of the Lake District. If this be so, the valleys of the district need not date back to any very remote period, and may even have been commenced in Tertiary times. § 4.— Origin of the Dome. It has been observed, that although the Lake District dome is a continuation westward of an anticlinal axis, it is, nevertheless, in a certain sense distinct from this axis. Not only is this the case, but it will be noticed, on examining a geological map of England, that the dome causes a marked asymmetry in the arrangement of the Carboniferous rocks. The north and south Pennine axis, and the east and west axis separating the coal-field of Yorkshire, Derbyshire, and Nottingham- shire from that of Newcastle, and that of South Lancashire and North Staffordshire from that of Cumberland, give rise to a cruciform 1 Trans. Cumb. and West. Assoc. 1885, p. 37. W. Upham—Work of Prof. H. C. Lewis. 155 arrangement of the coal-fields, but the north-west part of the cross is interfered with by the Lake District dome, and hence the Cambrian coal-field is of small dimensions as compared with that of Newcastle. Whilst the widespread movements which caused this cruciform arrangement were proceeding, a local movement has produced the asymmetry of the north-west portion. To what is this local move- ment due? Can the comparison with the laccolitic structure be carried further, and may we suppose that a lenticle of igneous rock lies at some depth below the Lower Paleozoic rocks of the Lake District? The evidence on this point is wanting. Most of the igneous rocks which penetrate the Lake District slates appear to have been intruded before the formation of the Carboniferous deposits, and the latter are remarkably free from igneous intrusions. ‘Those which do occur are of a basic character. The existence of the Whin Till indicates the occurrence of large masses of basic rock at a lower level, and it might be com- pared with one of the outlying sheets of the Henry Mountain laccolites. But the position of the igneous masses with which it is connected are not easy to fix, and the rocks of the Lake District and the surrounding area do not exhibit the abundance of basic dykes which one would expect in the vicinity of a laccolitic mass. There are a few dykes in the Carboniferous rocks of the Whitehaven district and near Ulleswater, and another dyke pointing to the Lake District is mapped by the geological surveyors in the Carboniferous rocks of Caton Green near Lancaster. Near the centre of the dome are several radial and tangential basic dykes, as seen in the geological map of the country around Wastwater, and these dykes are newer than the numerous acid dykes which cut through the same rocks, for they displace them. We may be allowed, then, to suggest the possibility of a mass of basic rock underlying and connected with the formation of the Lake District dome, without in any way insisting upon its probability. Be this as it may, the superimposed drainage of the Lake District appears to be an actual fact, and the occurrence of this is an interesting point in the fascinating study of the physical history of this beautiful and remarkable area. TiJ.—Tue Worx or Pror. Henry Carvitt Lewis In GLACIAL GEroLoGY. By Warren Uruam, of the United States Geological Survey. \HE recent notice! of the life and work of Prof. Henry Carvill Lewis, whose lamented death occurred in Manchester, July 21st, 1888, in his thirty-fifth year, well indicates the wide range of his scientific labours. He published valuable results of investiga- tions in astronomy, mineralogy and petrology, and especially in glacial geology, the last being based on his exploration of the drift 1 This Macazinz, III. Vol. V. pp. 428-430, September, 1888. A similar but more extended notice, with portrait, appeared in the American Geologist for December, 1888. 156 W. Upham—Work of Prof. H. C. Lewis. and its terminal moraines in the United States, and later in Ireland, Wales and England. The present article reviews his contributions to our knowledge of these drift formations and of the history of the Ice Age, bringing into comparison and correlation the glacial records of America and Europe. Comprehensive as were Professor Lewis’ observations and studies in this field, he was planning yet more thorough and extensive exploration of the drift in Britain, Germany and Scandinavia, when he was taken from us. In his death the geologists of two continents mourn the loss of a most gifted and faithful fellow-worker, who indeed already had achieved a grand life-work in the few years allotted to him. Professor Lewis first became specially interested in the glacial drift and the terminal moraine of the North American ice-sheet during the later part of the year 1880, when in company with Prof. G. F. Wright he studied the remarkable osars of Andover, Mass., the gravel of Trenton, N.J., containing paleeolithic implements, the drift deposits of the vicinity of New Haven, Conn., under the guidance of Professor Dana, and finally the terminal moraine in Eastern Pennsylvania, between the Delaware and Lehigh rivers. The following year Professors Lewis and Wright traversed together the southern border of the drift through Pennsylvania, from Belvi- dere on the Delaware west-north-west more than 200 miles across the ridges of the Alleghanies to Little Valley, near Salamanca, N.Y., and thence south-westerly 130 miles to the line dividing Pennsyl- vania and Ohio, which it crosses about fifteen miles north of the Ohio river. The report of this survey of the terminal moraine was published in 1884, forming volume Z of the Reports of Progress of the Second Geological Survey of Pennsylvania. With the similar exploration of other portions of this great moraine done a few years earlier by Prof. Chamberlin in Wisconsin, Profs. Cook and Smock in New Jersey. and the present writer in Long Island, thence east- ward to Nantucket and Cape Cod, and also in Minnesota, it com- pleted the demonstration of the formation of the North American drift by the agency of land-ice. The observations of the moraine in Pennsylvania detailed in this volume are summarized by Prof. Lewis as follows:—‘The line separating the glaciated from the non-glaciated regions is defined by a remarkable accumulation of unstratified drift material and boulders, which, heaped up into irregular hills and hollows over a strip of ground nearly a mile in width. forms a continuous line of drift hills (more or less marked) extending completely across the State. These hills vary in height from a few feet up to 100 or 200 feet ; and while in some places they are marked merely by an unusual collection of large transported boulders, at other places an immense accumulation forms a noteworthy feature of the landscape. When typically de- veloped this accumulation is characterized by peculiar contours of its own,—a series of hummocks, or low conical hills, alternate short straight ridges, and inclosed shallow basin-shaped depressions, which like inverted hummocks in shape are known as kettle holes. Large boulders are scattered over the surface; and the unstratified ull W. Upham—Work of Prof. H. C. Lewis. 157 which composes the deposit is filled with glacier-scratched boulders and fragments of all sizes and shapes.” From its lowest point in Pennsylvania, where it crosses the Delaware 250 feet above the sea-level, this terminal moraine of the ice-sheet extends indiscriminately across hills, mountains and valleys, rising over 2000 feet above the sea in crossing the Alleghanies, and attaining the maximum of 2580 feet on the high table-land farther west, being there “finely shown at an elevation higher than any- where else in the United States.” Preliminary outlines of Professor Lewis's work on the glacial drift of England, Wales and Ireland are given in his papers in the Reports of the British Association for 1886 and 1887; and the first of these also appeared in the American Naturalist for November, and the American Journal of Science for December, 1886, and in this Magazine for January, 1887. Their most important new contribution to knowledge consists in the recognition of the terminal moraines formed by the British ice-sheets, which Lewis traced across Southern Treland from Tralee on the west to the Wicklow Mountains and Bray Head, south-east of Dublin; through the western, southern and south-eastern portions of Wales; northward by Manchester and along the Pennine Chain to the south-east edge of Westmoreland ; thence south-easterly to York and again northward nearly to the mouth of the Tees, and thence south-eastward along the high coast of the North Sea to Flamborough Head and the mouth of the Humber. It is a just cause for national pride that two geologists of the United States, Lewis in Great Britain in 1886, and Salisbury’ the next year in Germany, have been the first to discover the terminal moraines of the ice-sheets of Europe. Like the great moraines of the interior of the United States, those of both England and Germany lie far north of the southern limit of the drift. Another very important announcement by Professor Lewis relates to the marine shells, mostly in fragments and often worn and striated, found in morainic deposits and associated kames 1100 to 1350 feet above the sea on Three Rock Mountain near Dublin, on Moel Tryfan in Northern Wales, and near Macclesfield in Cheshire, which have been generally considered by British geologists as proof of marine submergence to the depth of at least 1350 feet. These shells and fragments of shells, as Lewis has shown, were transported to their present position by the currents of the confluent ice-sheet which flowed southward from Scotland and Northern Jreland, passing over the bottom of the Irish Sea, there ploughing up its marine deposits and shells, and carrying them upward as glacial drift to these elevations, so that they afford no testimony of the former subsidence of the land. The ample descriptions of the shelly drift of these and other localities of high level, and of the lowlands of Cheshire and Lancashire, recorded by English geologists,? agree 1 American Journal of Science, III. vol. xxxv. pp. 401-407, May, 1888. 2 Quart. Journ. Geol. Soc. vol. xxx. 1874, pp. 27-42; xxxiv. 1878, pp. 383- 397; xxxvi. 1880, pp. 3851-5; xxxvil. 1881, pp. 351-69; and xlii, 1887, pp. 73- 120; also, Grow. Mac. Dec. II. Vol. 1. 1874, pp. 193-197. 158 W. Upham—Work of Prof. H. C. Lewis. perfectly with the explanation given by Lewis, which indeed had been before suggested, so long ago as in 1874, by Belt and Good- child! This removes one of the most perplexing questions which glacialists have encountered, for nowhere else in the British Isles is there proof of any such submergence during or since the Glacial period, the maximum known being 510 feet near Airdrie in Lanark- shire, Scotland.? At the same time the submergence on the southern coast of England was only from 10 to 60 feet,? while no traces of raised beaches or of Pleistocene marine formations above the present sea-level are found in the Shetland and Orkney Islands.* The work and writings of Professor Lewis emphasize the principle that glacially transported marine shells and fragments of shells, which occur in both the till and Boulder-clay and the modified drift in various parts of Great Britain, are not to be confounded with shells imbedded where they were living or in raised beaches, for only these prove the former presence of the sea. The drift deposits of England south of the terminal moraines traced by Lewis were regarded by him as due to floating ice upon a great freshwater lake held on the north by the barrier of the ice- sheet which covered Scotland, Northern England and the area of the North Sea, and on the south-east by a land barrier where the Strait of Dover has been since eroded. Under this view he attri- buted the formation of the Chalky boulder-clay in Hast Anglia, and of the Purple and Hessle boulder-clays in Lincolnshire and much of Yorkshire, to lacustrine deposition. But shortly after the British Association meeting in 1887 his observations on Frankley Hill in Worcestershire and thence westward°® led him to accept the con- clusion, so thoroughly worked out by other glacialists both in America and Great Britain, that there were two principal epochs of glaciation, divided by an interglacial epoch when the ice-sheets were mostly melted away. There can be little doubt that the con- tinuation of Lewis’s study of the drift in England, if he had lived, would have soon convinced him of the correctness of the opinions of Searles V. Wood, jun., Mr. Skertchly, and James Geikie,® that land-ice during the earlier glacial epoch overspread all the area of the Chalky boulder-clay, extending south to the Thames. Small portions of Northern England, however, escaped glaciation both then and during the later cold epoch, when the terminal moraines mapped by Lewis were accumulated; and these tracts of the high moorlands in Hastern Yorkshire and of the eastern flank of the 1 Nature, vol. x. pp. 25, 26, May 14, 1874; Guon. Mace. Dec. II. Vol. I. pp. 496-510, Nov. 1874. 0? 0g iga> 2 |, larity in their relative posi- a : @28: = |~ tions toeach other, and appear 5 Dest (S| 5 . . . ss 8 > WeliR & : & | = imsections cut at right angles S yl, = : @ @ | to P and M rudely rectangu- me 8 £ #820 38 /+ lar. At placesgrouped round # oO So &®D Sac sH 5 a h f ] = S = 285 64/2 the vesicles in the felspar pT 4 | . occur very fine acicular — ~~ —— 5 .:e20 6: : o |S crystals, which are brown and ng 3 iS PE 0 ig & = show a decided dichroism. 5 o'r o Sas Hom Ve ee 1N. Jahrbuch, 1886, Beilage- pS cao 30 “me tOe | 5 i OS are 2 eee St ails) Band aw spool pea ae a ees nc li 2 Kiwangaine lies 130 kilometres N.W. of Kilimandscharo. Dr. C. Ricketts—Changes in the Earth’s Crust. 165 These remind the observer of breislakite, although their presence in the felspar-substance instead of lining the vesicles may appear to contradict this diagnosis. If they be not breislakite they may possibly be cossyrite,’ but their smallness does not permit of a more definite determination. V.—On some Puysicat CHANGES IN THE Harry’s Crust. (Part IIT.) By Cartes Ricxerts, M.D., F.G.S. : (Concluded from p. 119.) (—* the western flanks of the Malverns, the Upper Silurians are folded in several great anticlinals and synclinals, formed parallel to the axis of the Hill itself. To the west of Ledbury and again near Woolhope these contorted strata dip beneath the Old Red Sandstone, which, as computed by Phillips, has a maximum thickness of 8000 feet,? that of the Upper Silurians being 2690 feet. The thickness of the strata of which the Longmynd is formed has been estimated by the Government Surveyors at not less than 26,000 feet, as exposed in their highly inclined edges; the beds dipping at an average inclination of 60° to the W.N.W.® They thus appear as if they had been tilted by pressure against the more ancient rocks of the Caer Caradoc Range. In each of these instances the immense accumulations formed may have had effect in causing the great disturbance to which the strata have been subjected. Whether the ridges of the Malverns or of the Caradoc Range are recognized as having once formed the summits of ancient mountains, or the dividing ridges between valleys, there is abundant evidence that a great thickness of sediment has been laid down in their vicinity, burying the slopes on their sculptured sides; the deposit being greater at a moderate distance, where the slopes extend deeper, than near the summits. An example affording more conclusive evidence of the nature of the causes by which contortions and cleavage are produced occurs in the neighbourhood of Llangollen. At three different periods during Paleozoic times, namely, the Lower Silurian, the Upper Silurian, and the Carboniferous periods, the area around Llangollen continuously sank below the sea-level whilst deposits were accumulating. Three times they were raised above that level, and at the same time these ‘deposits underwent denudation; 7.e. previous to the deposition of the Upper Silurians, the Limestone and later Carboniferous rocks, and again as we observe at present. During each of these periods _ valleys were excavated to a depth so great, that the summits so far presented a mountainous character that they were raised 1500 feet and more above the then sea-level. Previous to the deposition of the Upper Silurian strata, a pre- Wenlock valley was excavated in those of the Bala formation to a 1 H. Forstner, “ Ueber Cossyrit, ein Mineral aus den Liparitlaven von Pantel- leria,’”’ Zeits. f. Kryst. 1881, Y 348-362. 2 Mem. Geol. Survey, vol. i. pt. i. p. 102. 3 Siluria, 1859, p. 23. 166 Dr. C. Ricketts—Changes in the Earth's Crust. depth greater than that of the present valley; and in width extend- ing from Llansantfraid Glyn Ceiriog, to the Cyrn-y-brain mountain, a distance from each other of seven miles in a direct line. Between these two points, though the strata have been deeply cut into, by the formation of the present valley of the Dee, no traces of the older rocks are discovered. Upon each side of this assumed valley, especially where the Upper Silurian strata abut against the older or Bala rocks, bendings and foldings have taken place, and slaty- cleavage has been developed, whilst at Llangollen, half-way between the two localities, the beds are seen, in the course of the river Dee, lying in a horizontal position. It has been already shown that such foldings could not have resulted from compression produced solely by subsidence to the extent indicated by the thickness of the deposit. This may be considered to be further confirmed in the same locality, where a repetition of the circumstances has so far taken place, that a deep valley, formed by the denudation of this Wenlock rock, had its bottom covered with the Red Basement beds of the Carboniferous system, and was subsequently buried underneath a deposit of 1025 feet’ of limestone, which, instead of folding, has a dip of 15° only to the N.E., passing beneath 3000 to 4000 feet? of later Carbon- iferous strata. There are essential] differences in the character of the deposits in the two periods; the Silurian, consisting of fine mud, which, long after its deposition, would remain in a plastic state and readily yield when subjected to irregular pressure, whilst the lime- stone would soon consolidate and become rigid.’ In the Ingleborough district the Lower and Upper Silurians are greatly bent and contorted, and the muddy deposits are also cleaved ;* they were greatly denuded, and formed hills and valleys, previous to the deposition upon them of the Carboniferous lime- stone, ‘the lowest beds of which,” as Playfair (§ 197) remarked, “contain in them many fragments of stone which, on comparison, resemble exactly the schistus underneath.” A thickness of lime- stone, amounting to 600 feet, rests on the basset edges of the Silurians, and this is surmounted, as seen in the mountain peaks of 1 The Carboniferous Limestone and Cefn-y-fedw Sandstone of North Wales by G. H. Morton, F.G.S., p. 21. 2 The Coal-fields of Great Britain, by Professor E. Hull, 2nd ed. p. 99. 3 | have seen at least ten instances where the Carboniferous Limestone during the period of its formation had been locally raised above the sea-level, and had thus been exposed for a time to atmospheric action and erosion. In eight of the examples thin beds of coal were formed, either resting immediately on the sculptured surtace, or on a bed of clay which covered it; the thickest amounts to about a toot, at Ingleton; others varied down to a mere film of carbonaceous matter in the clayey deposit. Subsidence taking place, the deposition of the limestone again progressed to a great extent. The methods of weathering go to prove that the limestone had become consolidated previously to its elevation and erosion ; in some cases shrinkage joints are present, and are filled with calcite, which stands out in relief on the eroded sur- face; the condition of these small joints indicates that the limestone must have become solidified before being raised above the sea-level, prior to the formation of the coaly beds. In some instances angular or weathered fragments of limestone are embedded in the clayey deposit which fills hollows in the surface of the limestone. 4 They have been described in an Essay by Professor T. McK. Hughes, *‘ On the Break between the Upper and Lower Silurians of the Lake District,’ Gro, Mac. Vol. IV. p. 346. Dr. CO. Ricketts—Changes in the Earth’s Crust. 167 Whernside, Ingleborough and Penigent, by the Yoredales and Mill- stone Grit. These also were formerly covered by a considerable thickness of Coal-measures, as is evident from the presence of the Coal-field of Ingleton on the southern or down-throw side of the Great Craven Fault; whilst the whole series rested in a position as horizontal as when first laid down, though, in order to permit the accumulation of this succession of strata, they must have sunk con- tinuously whilst deposition progressed, until their base reached a depth of 4500 feet, as calculated by Professor John Phillips. The difference in the conditions of the two series is remarkable ; for if the foldings in the more ancient strata are attributable to lateral pressure, due to subsidence, they should have occurred also, at least to some extent, in the Carboniferous rocks in which subsidence took place to the depth of nearly a mile. It is therefore necessary to search for other causes likely to effect this pressure. Sir Charles Lyell, when commenting on the presence of the “mud lumps” at one or other of the mouths of the Mississippi, attributed their formation to ‘the downward pressure of the gravel, sand and sediment, accumulated during the flood season off the various mouths of the river, upon a yielding bottom of fine mud and sand. A mass of such enormous volume and weight, thrown down on a foundation of yielding mud, may well be conceived to exert a downward pressure, capable of squeezing and forcing up laterally some parts of the adjoining bottom of the gulf, so as to give rise to new shoals and islands.” He further states “that railway engineers are familiar with the swelling of a peat moss, or the bed of a morass, on some adjoining part of which a new embankment has been constructed.? A friend who, many years ago, was engaged in superintending the erection of a fort near the mouth of the Medway, relates that the unloading of a cargo of materials to be used in its construction caused a considerable deviation from the perpendicular, and great difficulty was likewise experienced in keeping the structure erect as it progressed, on account of the muddy deposit, on which the founda- tions rested, giving way irregularly. Captain CO. KE. Dutton, of U.S. Geological Survey, states that ‘“‘wherever the load of sediment becomes heaviest, there they sink deepest, protruding the colloid magma beneath them to the adjoining areas which are less heavily weighted, forming at once both syn- clinals and anticlinals.” * Though Lyell, as has been already remarked, considered that the intense pressure by which foldings of strata have been caused, has been exerted without violence, and in the most gradual manner, he omitted to apply the phenomena, described by him as occurring at the mouth of the Mississippi, in explanation of the cause of contortions in older rocks. 1 Report on the Probability of the Occurrence of Coal in the Vicinity of Lancaster, 37 o Principles of Geology, 10th edit. vol. i. p. 453. 5 The Karth’s Physical Evolution, The Penn Monthly, 1876, p. 424; also a resumé of the same, by Rey. O. Fisher, Grou, Maga. Dec. II. Vol. III. p. 374. 168 Dr. C. Ricketts— Changes in the Earth's Crust. It is deserving of consideration whether, and to what extent, fold- ings of strata, and other concomitant phenomena, have been depen- dent on varying accumulations of material. A river brings down and deposits a greater quantity and coarser particles, in an estuary or bay, or in the sea, along the direction of its current, than at a distance, where the finer mud is spread out; when this occurs above an underlying muddy deposit, there would be a tendency for the heavier materials to sink down and, producing displacement, so cause lateral pressure similar to that to which these foldings have been ) : , ML hii cco! mma if} ] / il i } Hf} / My y Mi Y A THM MMM Yih Mii} ee d Yip y Wy pp Mary 4 Ly L L li L Tl l z | LT ATT ATMO g y Ip i | ] ao Fig. 4. C, consolidated Clay ; B, layers of Clay, originally in horizontal beds, but squeezed into folds by the vertical pressure of S, sand, extra weight being applied. attributed since the days of Sir James Hall. Effects correspondmg to these suppositions can be readily induced by taking clay dried and reduced to powder and spread in consecutive layers of different colours horizontally in a box or trough. On the access of water, through holes previously made in the bottom and sides of the box rather than by pouring it on the surface (for that would prevent the free escape of the included air) the clay becomes soft and plastic ; when fully saturated, by pouring sand on the clay at some special part and applying extra weight, which will be requisite in the experiment, this will not only cause the heavier substance to subside into the plastic mass of clay, but, whilst pressing downward, it will at the same time squeeze outward the clay-beds, causing the layers immediately underneath to be formed into films; these, however thin, are still continuous with those on the sides, which are rendered considerably thicker than in the original state of the beds, and are curved into folds, representing contortions similar to what are con- stantly met with, having been produced under circumstances analo- gous to what must frequently occur from natural causes (see Fig. 4). That the form of the contortions may be greatly influenced by the contour of the solid ground is well illustrated in the effects produced by the presence of the mound (*) of consolidated clay (C) in the figured model. (The interior of the models was displayed by cutting through them, before they became solid, by means of a piece of string, previously arranged for that purpose.) From the great thickness of certain geological strata, from the amount of deposit known by borings to occur in the Deltas of great Dr. C. Ricketts—Changes in the Earth’s Crust. 169 rivers, and what may be inferred from the contour of bays, which are the submerged continuation of valleys into which rivers flow, there must be sufficient, perhaps more than sufficient, power developed, not only to account for progressive subsidence of the Harth’s crust, but also to induce simultaneously, when circumstances are favourable, such lateral pressure, in the manner suggested, as would terminate in contortion and cleavage. However frequently such contortions may occur at the present time, opportunities of proving their existence must indeed be rare, for, formed beneath the surface of the water, if by any means they should become raised above the sea-level, the exposed surface of such easily disintegrated materials would be soon washed away by the waves. The contortions which occur in metamorphic rocks must, at least in a great measure, be dependent on other causes than those which have been considered. The abrupt bendings they have sometimes undergone ; the wavy wrinkled state into which they are at other times thrown, indicate that, to use an expression made to me by the Scotch chemist and mineralogist, Professor M. F. Heddle, M.D. of St. Andrews, “they must be due to some internal change.” Mr. T. F. Jameson, F.G.S., “supposes that the heat from the interior of the earth gradually approached the base of the sedimentary beds and, by heating, caused them to expand and thereby become wrinkled into huge folds, as a necessary consequence of a great mass of swollen matter having to find room in the space occupied by the same matter when in a cold and contracted state.1 Considered alone, this does not appear an altogether satisfactory explanation of the formation of such contortions as sometimes occur in metamorphic rocks. If the abrupt bendings alluded to are entirely the result of expansion from being subjected to excessive heat, it might be expected that in all cases foldings would result to a greater or less extent; or that, if so great expansion does take place, on the cooling and consequent con- traction of the mass, the resulting fissures should, in gneissic and granitic rocks, have their sides separate from each other to a greater extent than is the case; the average width of which does not appear to be greater than in unaltered strata. The shrinkage of basalt and lavas forms prisms, the joints of which are in close contact with each other, though the mass in which they exist has cooled from an absolutely molten state. Mr. Charles Babbage’ calculated, from the result of experiments by Mr. H, C. Bartlett, of the United States Engineers, that if a mass of granite, twenty-five miles in thickness, be heated to 1000°, expansion would take place to the extent of 637 feet only; that is, there would be an extension of its bulk equivalent to about 34, of its size in a cold state. The results of other experiments, made by Mr. A. J. Adie, and by Mr. T. Mellard Reade,’ do not greatly differ from those of Mr. Bartlett. The expansion of rocks by increase of heat has by some been con- sidered to be the cause of elevation of the land. Doctor James 1 Quart. Journ. Geol. Soe. vol. xxvii. p. 105. 2 The Ninth Bridgewater Treatise, Appendix, p. 222. 3 Origin of Mountains, p. 109. 170 Dr. C. Ricketts—Changes in the Earth’s Crust. Hutton, in his celebrated work, states that “the power of heat for the expansion of bodies is, so far as we know, unlimited; but, by the expansion of bodies placed under the strata at the bottom of the sea, the elevation of those strata may be effected; the question to be resolved regards the actual exertion of this power of expansion, how far it is to be concluded as having been employed in the production of this earth above the level of the sea. There has been exerted an extreme degree of heat below the strata formed at the bottom of the sea, and this is precisely the action of a power required for the elevation of those heated bodies into a higher place. Therefore, if there is no other way in which we may conceive this event to have been brought about, consistent with the present state of things, or what actually appears, we shall have a right to conclude that such had been the order of procedure in natural things, and that the strata formed at the bottom of the sea had been elevated, as well as con- solidated, by means of subterranean heat.” ! This coincides with the hypothesis advanced by Mr. Charles Babbage, nearly forty years subsequently, as a cause of disturbances of the earth’s crust; having been suggested to him by the changes of level, proved to have occurred within a comparatively short period, at the site of the Temple of Serapis, in the Bay of Naples.2. Mr. T. Mellard Reade considers “‘mountain ranges are ridgings up of the earth’s crust, which take place only in areas of great sedimentation. That the existing cause of the various horizontal and vertical strains, ending in the birth of a mountain-range, is the rise of the isogeotherms and consequent increase of temperature of the new sedimentaries, and that portion of the old crust they overlie. The tendency to expand horizontally is checked by the mass of the earth’s crust bounding the locally heated area, and is therefore forced to expend its energies within itself; hence arise foldings of lengthening strata, re-packing of beds, ridging up, and elevatory movements, which occur in varied forms according to the conditions present in each case.” * He thinks “ this mass of rock cannot expand laterally, for in that case it would displace the crust of the earth surrounding the affected area, nor downwards, for that would displace the foundations of the earth itself. It is only free to expand upwards.” * The expression, “if there is no other way,” indicates that Hutton felt some misgiving in supposing the elevation of the strata was due to the effect of expansion from the accession of subterranean heat, and that he suggested the theory for want of a better. With respect to this proposal, as advanced by Babbage, the Rev. O. Fisher remarks that ‘‘the heat conducted upwards into the new deposits must be abstracted from the couches beneath, so that there can be no absolute increase in the amount of the heat beneath the area in question, except such as is supplied laterally.”* It therefore follows, that there would be as great a diminution in size of the contiguous 1 Theory of the Earth, by James Hutton, M.D., F.R S.E., 1795, vol.i. p. 128. Proc. Geol. Soc. vol. ii. p. 73; Quart. Journ. Geol. Soe. vol. iii. p. 186. Origin of Mountain Ranges, by T. Mellard Reade, C.E., F.G.S., p. 326. Pave 10. I’hysies of the Earth’s Crust, p. 82. o fF WO Dw Dr. G. Baur—On Scaphognathus, Newton. 171 portion of the interior mass as would be equivalent to the increased size caused by the heat supplied to the later formed strata. In- dependently of this, the calculations deduced from the expansion of rocks by heat, as determined by the experiments of Bartlett, Adie and Mellard Reade, indicate that when exposed to high degrees of temperature, the enlargement is not sufficient to induce more than a fractional part of what is attributed to it. Hlevation of land does not eccur where the greatest amount of accumulation is in progress; on the contrary at the mouths of great rivers, where simultaneously with, or rather, as is here contended, in consequence of the immense accretion of sediments derived from the erosion of the land, and brought down and deposited, subsidence has been proved to have taken place to a very great extent, forming conditions such as it is considered by most would render the deeply buried strata liable to be exposed to an increase of heat supplied from below. It is in those areas where the greatest amount of denudation has taken place, and the land has become lightened in the process of removal, that elevation occurs. It is evident that where foldings occur, in what may be designated unaltered strata, they have been formed at the sea-level or at some moderate depth ; if in those in which extensive chemical change has produced a re-arrangement in their constituent components, they have been buried beneath a very thick covering of strata, which has enabled them to become affected by internal heat. However high they may subsequently have become elevated, this pre-supposes the removal of this immense quantity of material before the metamorphic rock became exposed at the surface, and formed a portion of the structure of mountains. From the examination of the geological structure of Britain it is seen that the erosion of these hard rocks, and their formation into hills and valleys, during a former period, though they may have sub- sequently sunk below the then sea-level, and been deeply buried beneath large accumulations of sediment, have still had a great effect in determining the present contour of the land. The flanks of buried valleys and the summits of ancient hills again become elevated and exposed by the removal of the less consolidated strata; the hardness and indestructibility which preserved them before, again enables them to stand conspicuous at a higher altitude than later deposits, and to form what has been called “the core of the mountain”; even the old valleys sometimes again serve the purpose by and for which they were originally formed; and streams run in them in the same course, often in the identical old channels. VI.—Mr. E. T. Newron on PreRosavrgia. By Dr. G. Baur, New Haven, Conn. Vee paper by Mr. E. T. Newton! “ On the Skull of Scaphognathus ” is one of the most important contributions to the morphology of 1 Newton, E. T., “‘ On the Skull, Brain, and Auditory Organ of a New Species of Pterosaurian (Seaphognathus Purdonz), from the Upper Lias near Whitby, York- shire,” Philos. Trans. Lond. 1888, vol. 179, pp. 303-687, pl. 77-78. 172 Dr. G. Baur—On Scaphognathus, Newton. the Pterosauria } which has been published. There are a few points. however, which appear to me to need correction or a fuller explanation, 1. The “prefontals,’? Newton. When Mr. Newton had the great kindness to show me the specimen, which he had worked out with so much skill, I suggested to him that the bones called by him “ prefrontals ” (loc. cié. p. 505) were probably parts of the nasals only. It seems to me quite probable that this view is correct, and I give the following reasons: 1. If the “ prefrontals,” Newton, represented these bones, they would have a position different from that in any other form of the Monocondylia, Haeckel, 1866 (Sauropsida, Huxley, 1869). They would be placed inside of the nasals. 2. They would not form a part of the orbit, a condition found in all the Monocondylia in which a prefrontal is present. As we can hardly expect such a fundamental difference between the Pterosauria and the other reptiles, this view is very improbable. But Mr. Newton remarks, if the bones called prefrontal and nasal represent a single element, there will be no distinct prefrontal bones. In fact, the prefrontal is not free in the Pterosauria, exactly as in birds. The prefrontal probably forms the anterior and outer process of the frontals, contributing to the upper anterior border of the orbit, or it may be co-ossified with the lachrymal, as stated by Dr. Ginther. The processes of the frontal, which I am inclined to consider as prefrontals, are well represented in figs. 1, 2, 3 in Mr. Newton’s memoir. The figure given by Hallmann? represents the relations very well. The bones called “nasals” and ‘“‘prefrontals” by Mr. Newton therefore represent only one pair of bones, the nasals. 2. The quadrato-jugal and jugal. The exact connection between these bones is now determined, by Mr. Newton’s studies, for the first time; but the peculiar resem- 1 T use the name Prerosauria, which was introduced by Kaup in 1834 in the form “‘ Pterosaurii” (Kaup, J. J., ‘‘ Versuch einer Kintheilung der Saugethiere in 6 Stamme und der Reptilen in 6 Ordnungen,” Isis, 1834, p. 315. In the same year Carus established the group “ Alata”’ to contain Prerodactylus (Carus, Carl Gustav: Lehrbuch der vergleichenden Zootomie, 2 Aufl. Leipzig, 1834, pt. i 25). In 1835 de Blainville called those reptiles the Pterodactylia (preoccupied by Latreille, 1825, for a ‘‘ family of Birds,” Ptercdactyli) (de Blainville, H., “ Descrip- tion de quelques espéces de Reptiles de la Californie, précédée de l’analyse du systeme général erpétologie et d’amphibiologie,’’ Nouv. Ann. du Musée, tome iv. p. 288, Paris, 1835). In the same paper the Ichthyosaurs are separated from the Plesiosaurs, under the names Ichthyosauria and Plesiosauria. These names antedate the Ichthyopterygia and Sauropteryyia of Owen by twenty-five years. Ornithosaurt was used by Fitzinger in 1837 (Ann. Wien Mus. Naturg. 1837, vol. ii. p. 184), and adopted by Bonaparte in 1838 (Nuovi Annali delle Scienze naturali, Bologna, 1838, vol. i. pp. 891-397). In 1841 Owen gave the name Pterosauria (Brit. Assoc. Rep. (1840), London, 1841). > Hallmann, Eduard, ‘‘ Die vergleichende Osteologie des Schlafenbeins ”’ (Hanover, 1837), pl. ii. fig. 4. Dr. G. Baur—On Scaphognathus, Newton. 173 blance between these elements and the corresponding bones in the Sauropoda? is not stated. In both, the jugal has two upper processes, which form the anterior and inferior part of the orbit. In Diplodocus the quadrato-jugal is connected directly with the maxillary ; a condition which seems to exist in Scaphognathus. Newton says the maxillary ‘comes below the lower angle of the jugal, and seems to meet the quadrato-jugal” (p. 505). Some of the Testudinata (Staurotypus, Aromochelys ... ) show a similar structure. The tendency of the quadrato-jugal in Scaphognathus to separate the postorbital from the jugal is very remarkable. 3. The “ supra-temporal.” « At the outer end of each paroccipital process, and forming the hindermost angles of the skull, there seems to have been a small separate bone, which occupies the position of, and probably is thie supratemporal, a bone said to be constantly present in Lizards.” (Newton, p. 507.) A supratemporal bone has not been found in any member of the group to which the Pterosauria belong. It is absent in the Phyto- sauria, Crocodilia, Dinosauria, and Aves. This makes it probable, that it did not exist as a free element in the Pterosauria. ‘The supra- temporal, Newton, may be only a part of the paroccipital or squamosal. 4. The “basipterygoid processes.” Mr. Newton suggests the possibility that these processes may be separate bones {p. 507), but on p. 509 he is inclined to consider these as elongated basipterygoid processes. It is quite evident that they cannot represent anything else.? In the Sauropoda they are developed in the same way. 5. Some notes on the synopsis of genera of the Pterosauria given by Mr. H. T. Newton. In his “ Notes on Pterodactyls” * Mr. Newton follows Lydekker in adopting his (Lydekker’s) genus Ptenodracon.* This name is a synonym of Ornithocephalus, Seeley (non Som- mering). Both Lydekker and Newton say, without apparent authority, that Zittel® had shown Seeley’s name Ornithocephalus to be inadmissible. Zittel did not admit Ornithocephalus, Seeley, 1 Marsh, O. C., “‘ Principal Characters of American Jurassic Dinosaurs, part vil. On the Diplodocide, a new family of the Sauropoda,” Amer. Journ. Sci. vol. xxvii. (Febr. 1884), pl. iil. figs. 1-3. 2 Prof. Fraas considered these parts even as ‘‘ hyoids,’’ Paleontographica, vol. XXY. 3 Newton, E. T., “ Notes on Pterodactyls,” Proc. Geologists’ Assoc, vol. x. No. 8, 1888. 4 Lydekker, Richard, ‘“‘ Catalogue of the Fossil Reptilia and Amphibia in the British Museum,’ Part i. London, 1888, p. 3. 5 Zittel, Karl. A., ‘‘ Ueber Flugsaurier aus dem lithographischen Schiefer Bayerns,”’ Paleontographica, vol. xxix. 1882, p. 80. 174 Reviews—Chev. Jervis’s Treasures of Italy. because he considered it to be the same genus as Pterodactylus, and this was his only reason for rejecting the name. Zittel’s words are: “Die Gattung Ornithocephalus (Sommering) ” wird von Seeley folgendermaassen characterisirt : ‘ Ornithocephalus. —The anterior nares are entirely separated from the middle holes of the head, both being small and the latter exceedingly small. The head is short. The neck is short. The large ischium appears to be excluded from the acetabulum, and the ilium appears to extend less far forward than in Pterodactylus.’ Diese Diagnose stiitzt sich lediglich auf die ungenaue Abbildung Sdmmering’s. Hs bedarf nur eines Blickes auf Taf. xii. fig. 8 [in Zittel’s work], sowie auf die obigen Bemerkungen um sich zu tberzeugen, dass die fur die Gattung Ornithocephalus angegebenen Merkmale theils am Original garnicht vorhanden sind, theils ihre Erklirung in dem Erhaltungs- zustand finden. Ornithocephalus, Sommering,' fallt somit, wie schon alle friheren Autoren annahmen, unter die Synonymik von Pterodac- tylus.” If “ Ornithocephalus brevirostris, Sommering,” is different from Pterodactylus, the name Ornithocephalus, restricted by Seeley to this species, has to stand, and not Péenodracon, Lydekker. The genus Ornithopterus (v. Meyer, 1838), of which Huxley says, “J am much inclined to suspect that the fossil upon which the genus Ornithopterus has been founded appertains to a true bird,” is still considered by Newton as a distinct genus of the Pterodactyls. Prof. Huxley and Newton have overlooked the fact that H. v. Meyer retracted this genus in 1860, in his great work, “‘ Reptilien aus dem lithographischen Schiefer des Jura.” H. v. Meyer,’ after the examination of the original specimen, explained that his former statement was incorrect, and that his Ornithopterus could not be distinguished from Rhamphorhyuchus, and was probably identical with Rhamphorhynchus Gemmingi. J Sy dah W/ IEE Was J.—Tue SuBTeRRANEAN TREASURES OF ItTaLy. (“I Tresori Sotter- ranei dell’ Italia,” &., per il Cavaliére Guglielmo Jervis, Con- servatore R. Mus. Indust. Ital., F.G.S., &e.) Part IV. Complete in itself. The Economic Geology of Italy. 8vo. pages xxxv1 and 516. With 62 Woodcuts and Lithographs. (EE. Loescher, Turin, Florence, and Rome, 1889.) i a fourth and last volume of Chevalier Jervis’s valuable work on the underground riches of Italy treats of the topographical distribution of the stones and marbles useful for building and decoration, for architectural ornaments and sculpture; also for making lime, cement, mortar, stucco, plaster, etc. Not only are particular localities carefully described and often illustrated, but the 1 Zittel ought to have written Ornithocephalus (Seeley). 2 Meyer, Hermann v., ‘‘ Reptilien aus dem lithographischen Schiefer des Jura in Deutschland und Frankreich.’’ Frankfurt-a. M. 1860, p. 141. Reviews—Chevr. Jervis’s Treasures of Italy. 175 geology of the district and its component rocks or strata are briefly noticed in smaller type. There are, further, short historical sketches of the uses to which the materials have been applied during the course of thirty centuries, by the Htruscans and Romans, and by the Greek, Evyptian, Phoenician, and Pelasgian colonists of Southern Italy, and their several descendants down to our own times. Hence we are here shown of what stones a very considerable number of classic temples and other edifices, monuments, tombs, votive altars, and statues were constructed. Descriptive notices also are given of catacombs, aqueducts, roads. bridges, and other public works of the ancients and moderns,—all from a geological stand- point. Thus the great antiquities of Italy have been brought forward in a novel and highly intelligent and interesting manner, far beyond the reach of existing Guide-book literature; and both tourists and others can, like true students, not merely seek to collect new facts, but study known facts better. The localities of rocks of economic value (excepting sands and clays) are indicated, that are within accessible distances from towns, roads, railways, and ports. Some of the most interesting places referred to as containing objects worthy of notice by the lithologist and geologist, as well as the antiquary, are—Volterra, Cortona, Carrara, Fivizzano, Lerravezza, Rome, Tivoli, Naples, Pozzuoli, Syracuse, and Sardinia. Our author seems to us to have succeeded in carrying out Pliny’s object, when he was striving (as he said 1800 years ago) to treat old subjects in a fresh readable light. The old Roman’s opinion is given as an epigraph to the Introduction at page xx1, and may be read as follows :—“ It is difficult to give novelty to ancient things and authority to new; brightness to obsolete and light to obscure things; pleasure to the fastidious and faith to the doubting; a naturalness indeed to everything and everything to its own nature.” This volume mainly consists of three parts. 1. The Alps (pp. 82-164, with 19 illustrations) ; 2. The Apennines and the volcanoes, both active and extinct (pp. 165-414, with 80 illustra- tions); 38. The Islands of Sardinia and Sicily (pp. 417-482, with 9 illustrations). These regions are treated in detail according to their hydrographic basins, provinces, and communes, which yield building-stone, marble, ete. A list of the Illustrations is given at pp. x1—xrv, with indications of the materials used in the several buildings shown,—as, for instance, part of a Pelasgian wall at Croton (Cortona), made of great blocks of Eocene sandstone (pietra serena) ; part of Etruscan funereal monument, in Miocene alabaster; Etruscan mortuary tomb, of Quaternary travertine; the “cloaca maxima” at Rome, con- structed of Post-phocene volcanic tuff, of travertine from Tivoli, and of Post-pliocene peperino; Roman amphitheatre at Verona, of compact Jurassic marble; the Pantheon at Rome, with granite columns; the baker’s house at Pompeii, with mill-stones of late Tertiary leucitic lava; pavement of the “ Via Appia,” of Post- pliocene basalt; pavement of the Roman mole of Puteoli (Pozzuoli), 176 Reviews— Chev. Jervis’s Treasures of Italy. of Post-pliocene trachyte of the Solfatara; triumphal arch of Augustus at Susa, the cathedral of Milan, and the front of the Palazzo Madama, Turin, of white Pre-paleozoic marble; and the Railway-station at Turin, of Pre-palzozoic syenite and gneiss. The sources of the material of these and of the numerous other pictured buildings, statues, ete., are carefully given. Besides those mentioned above there are views and sketches of the mountainous districts that yield marble, of some quarries, and the rough modes of hauling the blocks by means of cruelly used bullock-teams; also of Vesuvius, Lipari, Pompeii, cement-factories, palaces, churches, bridges, statues, catacombs, cave-dwellings of Posilippo, ancient amphitheatres and temples (Roman and Greek), and of the enigmatical pre-historic buildings (Nuraghi) of Sardinia. At page xv is a list of sixty-five authors who have described the economic stones and other such Italian materials used in construction, decoration, inlaying, ete. The Preface and an Introduction, explaining the author’s plan and intention, with a brief exposition of the bearing of Geology on the subject of his work, follow appropriately to page XXXII. At p. xxx a list of the economic rocks of Italy (eighty-nine) described in this volume is given. ‘The effects of atmospheric action on the different kinds of rock and stony materials are noted at pp. XXXIV-XXxv; and the relative composition and character of cements, mortar, and plaster, at p. XXXVI. Page 1 commences with a catalogue of the ancient and modern names of places, the economic geology of which is mentioned in the volume. At pages 2 and 8 is a provisional or tentative Table of the chief geological formations occurring in the Italian Alps, according to the writings of accredited geologists, with indications of the different economic materials found in or made from the several rocks. At pages 4 and 6 is a similar carefully-constructed Table of the rocks and strata of the Apennines and their associated volcanoes. A similar Table for Sicily is presented at pp. 6 and 7; and one for Sardinia at p. 8. A concise list of leading Fossils for each of the above-mentioned regions is given at pp. 9 and 10. Pages 11-13 are occupied by a classified and alphabetical list of the Communes and Provinces mentioned in the Volume, with the respective numbers of the paragraphs concerned. At p. 32 is a list of fifty-five modern cities where Italian marbles, or ornamental and kuilding stones have been used. Not only is this volume full of matters of general interest to the educated reader, but it is a valuable repertory of useful information for provincial and communal administrations, for capitalists, technical colleges, and geologists. Two useful and carefully compiled Indexes complete the volume. 1. An Alphabetical Index of the Communes in which the several economic materials described in the volume, and here arranged under their lithological headings, have been met with. 2. A simply Alphabetical Index of the Communes in which the said rocks have been found. Reviews—Prof. K. v. Zittel’s Palichthyology. LZ Vols. i.—iii. of Signor Jervis’s “‘Subterranean Treasures of Italy” treat of the ‘“Topovraphical Mineralogy” of that kingdom, under the three same geographical headings as are used in vol. iv. These three earlier parts (1873, 1874, 1881) constitute a work complete in itself (price 40 lire); and so does vol. iv. (price 15 lire). We have already’ recommended with pleasure some of Signor Jervis’s books on the fossil fuel, mineral waters, etc., of Italy; and now we again can only praise his long-continued efforts for thirty years (we believe), in gathering together and publishing in convenient form so many well-considered facts and so much information valuable for thinkers, workers, and capitalists, not only in his adopted country, but throughout the civilized world. This too is the more creditable to him, as he has not spared his private means, any more than his _ arduous and continuous exertions in travel and research. We hope and trust his labours will be rewarded with the honour and profit so well deserved. Jide IJ.—Pror. Dr. von Zitten on PaicHTuyoLoey. Kart A. von Zitrren, HanpBucH peek PatmontToLocizr. PaLmo- zootoctgE. Band III. Lief. J. Il. (R. Oldenbourg, Munich, 1887-88. (Continued from page 130.) Drpnotr. HE chapter on Drpnot commences with a list of the more im- portant works relating to its recent representatives, and an interesting brief discussion of the systematic relationships of the group. ‘To the Ctenodipterini are referred Dipterus, Ctenodus, Paledaphus, Holodus, and other more fragmentarily-known fossil forms; and a supplementary section includes Megapleuron, Concho- poma, and the problematical Tarrasius. Ceratodus is the only fossil genus of Sirenoidei; and Dr. Fritsch has recently suggested that this is wrongly thus placed, exhibiting no characters by which it can be separated from the Ctenodipterini.” GANOIDEI. A long introductory section to the important group of Ganoids comprises, in addition to the usual general topics, a number of valuable, and, to a large extent, novel remarks upon the various stages of development met with in the vertebral column of these fishes, illustrated by several woodcuts. Commencing with the notochordal forms, and then referring to the false appearance of vertebree in the Pycnodonts, Dr. v. Zittel proceeds as follows: ‘As a rule there first appears on the underside of the notochord an arched bony plate (hypocentrum), which in the caudal region is clasped by the inferior arches and sends upwards shorter or longer 1 Grou. Mac. Dec. II. Vol. VII. June, 1880. * Fauna der Gaskohle, vol. ii. pt. 3 (1888), p. 68. DECADE III.—VOL. VI.—NO. IV. 12 178 Reviews—Prof. K. v. Zittel’s Palichthyology. lateral processes. Sometimes also the hypocentrum consists of two pieces, which meet together beneath the notochord. Besides the hypocentrum there is seen somewhat above on both sides a keel- shaped plate (pleurocentrum), pointed below but rounded above, by which the notochord is partly, though not completely, enclosed. In the next stage both the upwardly pointed hypocentra and the downwardly pointed pleurocentra extend so far, that a zig-zag appearance is produced laterally, and as the two pleurocentra also often unite on the dorsal aspect, the vertebra is now formed of two thin horse-shoe-shaped half-rings, completely encircling the noto- chord. In such half-vertebre the upper arched pieces (pleurocentra) never partly overlap the lower pieces (hypocentra), as Heckel has erroneously stated. In the genus Hurycormus the vertebral column consists in its front half of about equally developed horse-shoe-shaped half-rings, while in the caudal region the attenuated ends of the hypocentra and pleurocentra unite dorsally and ventrally, thus forming two closely apposed delicate rings completely surrounding the notochord (‘falsche Hohlwirbel,’ Vetter). The caudal region of the recent genus Amia exhibits this stage, except that the ossifica- tion has proceeded further inwards and to a great extent constricted the notochord. In a number of Jurassic Lepidosteoids ( Aspido- rhynchus, Belonostomus, Histionotus, Ophiopsis) and Paleozoic Crossopterygians (Rhizodopsis, Megalichthys), the vertebral centrum consists of a single thin cylindrical ring with a smooth or vertically striated outer surface. That the ‘Hohlwirbel’ or ‘ Ringwirbel’ results from the lateral fusion of two half-rings, is conclusively proved, for example, by Aspidorhynchus, for here the caudal region always consists of hollow vertebrae (Hohlwirbel), while the front abdominal region mostly consists of half-vertebra, of which the hypo- and pleuro-centra form rings closed dorsally and ventrally, but remain completely separated by a suture laterally.” In the systematic description of the Ganoids, the doubtful frag- mentary remains described by Pander from the Upper Silurian of the Island of Oesel are briefly noticed; and then follow the three problematical “ orders” of Pteraspidee, Cephalaspidee, and Placodermi. Alth’s determination of the simple shield named Scaphaspis, as placed ventrally beneath the more complex shields of Pteraspis and COyathaspis, is adopted; and the restored figure of the two connected shields of Pteraspis is reproduced. These fossils are common in the Old Red, not of Scotland (as stated), but of Western England. We would also remark that Pal@aspis, Claypole, so far as defined, falls in the genus Holaspis. A very complete synopsis of the Cephalaspide is given, including references to the species ; and the histological remarks are illustrated by Huxley’s figures of microscopical sections of the shields. Both these groups have been so well treated by Ray Lankester, that it is comparatively easy to summarize our present knowledge of their various representatives ; but with the Placodermi the case is very different, and a carefully prepared digest of the existing literature of the subject shows how much revision of the typical Huropean genera is required. Such a Reviews—Prof. K. v. Zittel’s Palichthyology. WAG, revision is now in progress by Dr. R. H. Traquair, and three con- tributions to the subject have already appeared.? A few genera “‘incertee sedis” succeed the Placodermi, e.g. Menaspis, Oracanthus, Stichacanthus, etc. Of these, Oracanthus is now definitely proved to be an Elasmobranch ;” and all the associated forms, except Menaspis, will doubtless share the same fate when microscopically examined. The more typical “‘ Ganoids” are commenced with the Chondros- tei, of which only two families are recognized—the Acipenseridee and the Spatularide. Of the former, Acipenser toliapicus, Ag., is recorded from the London Clay of Sheppey, and we might add A. ornatus, Leidy, from the Miocene of Virginia? The supposed existence of the family Spatularide in the Devonian age (Macro- petalichthys) is incredible; and the recent researches of Davis‘ and Traquair® upon the Liassic Chondrosteus prove conclusively that this genus belongs to an otherwise unknown extinct family. As indicated by its generic name, Crossopholis possesses small pectinated scales, and these are worthy of note inasmuch as they necessitate the modification of one point in the stated family-definition. The Acanthodidee follow the Chondrostei, and are raised to the: rank of an order, without, however, any subdivision into families. Huxley’s conclusion is adopted. that these fishes are intermediate between Selachians and Ganoids; and the principal genera are briefly noticed. The order of Crossopterygide occupies the next: eighteen pages; and the first family is typified by Phaneropleuron, which some authors would place in the Dipnoi.. The Ccelacanthidee are treated mainly in accordance with Reis’ recent memoir;® and then follow the Devonian and Carboniferous genera included by Huxley in his families Saurodipterini and Glyptodipterini. The latter have been remarked upon lately by Dr. Traquair in the pages of this Macazine;’ and the most recent information concerning Devonian Crossopterygians will be found in this article. Polypterus naturally closes the systematic consideration of the Crossopterygian Ganoids, though no members of the Polypteride or Polypterini have hitherto been detected among fossils. Next are. placed the Paleeoniscidee and Platysomide, grouped together in an order named by the author, Heterocerci, and unaccountably removed: far from the Chondrostei, with which they are associated by Dr.: Traquair, whose elaborate detailed researches form the basis of the chapter. It is unusual, indeed, not to place the Crossopterygians before the Actinopterygians, as being referable to a lower stage of fish-evolution ; and if the definitions of ‘“‘ Chondrostei”’ and “ Hetero- ' Guou. Mac. [3] Vol. V. (1888), pp. 508-511 (General) ; ibid. Vol. VI. (1889), pp. 1-8, pl. 1. (Humostews).—Ann. Mag. Nat. Hist. [6] vol. ii. (1888), pp. 485-504, pls. xvii. xvill. (Asterolepide). ‘ Gxrou. Mae [3] Vol. V. (1888), p. 85. Rep. U.S. Geol. Surv. Territ., vol.i. pt. i. p. 350, pl. xxxii. fig. 58. Quart. Journ. Geol. Soc. vol. xliil. (1887), pp. 605-616, pl. xxiii. Geou. Mae. [8] Vol. IV. (1887), pp. 248-257, woodcuts. Paleontographica, vol. xxxv. (1888). Grou. Mae. [3] Vol. V. (1888), pp. 512-516. “arn on fF Ww w 180 Reviews—Prof. K. v. Zittel’s Palichthyology. cerci”’ had been given i uniform terms, side by side, we venture to think that the illogical nature of their separation would have become apparent. The Chondrostei are said to be destitute of scales and branchiostegal rays, while the Heterocerci are characterized by both these structures well developed ; and these are the sole differences of importance recorded. Nevertheless, Chondrosteus is termed a Chondrostean, while the fact is omitted that its numerous large branchiostegal rays were described and figured by Egerton thirty years ago; and one of the Chondrosteans mentioned (Crossopholis) has the flank-scales even more developed than those of an admitted member of the Paleoniscidse, Phanerosteon. Under such circum- stances, Dr. v. Zittel’s proposed rearrangement is far from being an emendation of Dr. Traquair’s results, and must be regarded as a decidedly retrograde step. On reaching the Order ‘ Lepidosteide,” the influence of the author’s own researches soon becomes apparent; the Paleontological Museum of Munich containing so large a series of fine Lepidosteoids from the Bavarian Lithographic Stone. Several rearrangements of species are proposed, with one or two new genera; and there are many original figures, drawn from actual specimens, giving much precision to our knowledge of osteological characters. None of the families, however, are named from the typical genera; and in the first division (Stylodontide) we observe one genus (Dictyopyge), which, if Dinkel’s original drawings are correct, contradicts one point in the ordinal definition (“‘ Trager der unpaaren Flossen ebenso zahlreich als die gegliederten Strahlen”’). The extreme forms of the Stylodontide are Geol Mag. 1889. i West,Newman&Coamp. arters paper. thered’s paper. THE GEOLOGICAL MAGAZINE. NEW SERIES. DECADE Ill. VOL. VI. No. V.—MAY, 1889. ORIGINAL ARTICLILEHS. I.—Own Fosstz Isopops, with A Description oF a New SpEcrEs. By James Carter, F.G.S, (PLATE VI. Figs. 1—7.) HE recent discovery in the Woodwardian Museum of an un- described species of Isopod from the Upper Greensand of Cambridge affords an opportunity for the revision of the entire list of that class of fossils. The total number of species which have hitherto been described as occurring in a fossil state is inconsider- able,—probably scarcely thirty—including both foreign and British. To what extent this small number expresses the variety of specific form of this tribe of Crustaceans, which actually existed during the period of deposition of the several rocks in which their remains occur, it is impossible to determine, as doubtless by far the greater proportion of the individuals perished by reason of the delicacy of their tissues—the larger and thick-shelled species only having been preserved—the small, thin-shelled kinds not admitting of recogniz- able ‘‘fossilization.” Specimens of Jurassic and Cretaceous Isopods are very rare both as to variety and individual number, and it may be inferred that this rarity of occurrence results from the more or less turbulent conditions under which these marine deposits were formed. The Tertiary estuarine and freshwater species, buried under more tranquil conditions, are much better preserved, and occur in some localities in innumerable abundance—Spheroma, Archeoniscus, ete. The succession and geological distribution of Isopods, so far as has yet been ascertained, is indicated by the following list :— One species has been obtained form the Old Red Sandstone. ? One ,, Be the Triassic rocks. Five ,, is the Jurassic _,, Three ,, a the Cretaceous ,, Highteen the Tertiary ,, 9? About three-fourths of the forms enumerated are foreign, and seven species have been recorded by Dr. Woodward as occurring in this country :— Prearcturus gigas, H. Woodw. ... ... ... Old Red Sandstone, Hereford. Archeoniscus Brodiei, Milne Edwards ... ... Purbeck Beds, Vale of Wardour. ‘D Edwardsii, H. Woodw. ‘ on Re Palega Carteri, H. Woodw. ... ... ... ... Grey Chalk, Dover. Bopyrus sp. (parasitic) ... ... ... ... ... Greensand, Cambridge. Lospheroma fiuviatile, H. Woodw.... ... ... U. Eocene, Isle of Wight. Smithii, H. Woodw.... ... ... 90 99 3? DECADE III.—VOL. VI.—NO. Y. 13 194 James Carter—On Fossil Isopods. To this list may be added Palega McCoyi, the new Cretaceous form described in this paper, thus making a total of eight species as representing the fossil Isopods in Britain. In Phillips’s Geology of Oxford and Valley of the Thames, p. 122 (1871 ed.), the genus 4iya is mentioned in a list of Liassic fossils, but no specific name, figure or description is given. In investigating a tribe of genera it is obviously desirable not only to consider each genus separately and distinctly, isolated from its allies, but also to consider it with reference to other forms, so as to determine its relationship and phylogeny, and the precise zoological position which it occupies. To do this at all completely is as difficult as it is interesting, even with reference to living organisms ; but with regard to those which occur only in a fossil, and consequently in a more or less imperfect, condition, the difficulty is increased ; and in the case of the Isopods—as indeed in that of the innumerable host of perishable organisms which doubtless existed in geological periods—it is well-nigh hopeless to attempt such an enquiry, inasmuch as the supply of material in the shape of speci- mens is so extremely limited. It may, however, be useful to give collectively a brief epitome of the publications of the few paleeonto- logists who have written upon the subject up to the present date. In 1879 Dr. H. Woodward, who is well known to have long given special attention to, and to have contributed so largely towards a knowledge of, fossil carcinology generally, made a valuable communication to the Geological Society (Q.J.G.S. vol. xxxv.), in which he has given a list of described species of Isopoda, including the seven already alluded to as being British, and seven foreign ; and has added copious notes and observations. Dr. Ludwig von Ammon, of Munich, has published an able and exhaustive paper—“ Hin Beitrag zur Kenntniss der fossilen Asseln ” (Sitzungsber. d. Math.-Phys. Classe der k. k. Akad. d. Wissensch. 1882, Heft iv.), in which he has described a new species of Palega (P. scrobiculata), and critically reviewed, with abundant bibliographical references, the contributions of various authors who have written upon Isopods. He has also compiled a_ table, systematically and stratigraphically arranged, of all the species which he regards as true Isopods, including those which Dr. Wood- ward had previously enumerated, and adding the ten following :— ‘Isopodites triassicus, Picard, Trias. (A doubtful form.) Urda rostrata, Munst. Solenhofen, >> punctata, 99 D9 Aigites Kunthi, vy. Ammon ,, Palega serobiculata, vy. Ammon, Tertiary. From the “ Unter oligocaen,” Tyrol; a large species very nearly allied to Palega Carteri, Woodw. Oniscus convexus, Koch und Berendt, Tertiary (in Amber). Trichoniscus asper, Menge, 4 Porcellio notatus, Koch und Berendt, a », granulatus, Menge, 59 », eyclophorus, Menge, 3h The five last mentioned are terrestrial Oniscidz, of small size, and nearly allied to recent forms. A new Mexican species of James Carter—On Fossil Isopods. 195 Spheroma (S. Burkartii, Bare.), is described by M. Barcena (Geological Record, 1875, p. 297). The Guotocican MaGazine for April, 1887 (Vol. IV. p. 189), contains a notice of a paper On New Neogene Isopoda,” by N. Andrussow, in which mention is made of the following :— Cymodocea Sarmatica, Andr. A marine genus of the Spheromide. Palega Anconitana, Andr. Spheroma Catullit, Zigno. at exsors, Hichw. Bull. de Moscou, 1868. Cymatoga Jazykowti, Kichw. Cretaceous, Bull. de Moscou, 1863. Lastly, let me add that Prof. K. A. von Zittel (Handbuch der Palzontologie, 1885, pp. 666—670) gives, besides the foregoing :— Arthropleura ornata, Jordan, Coal-M. Saarbriicken. Archeospheroma Frici, Novak, U. Miocene, Bohemia. Spheroma faveolatum, Costa, Post-Tertiary, Calabria. Armadillo molassicus, H. v. Meyer, U. Miocene, Oeningen in Baden. On Palega McOoyi, sp. nov. Plate VI. Figs. 1—7. The species about to be described is represented by three specimens from the Cambridge Upper Greensand, one of which exhibits the cephalon and first two segments of the pereion, another is tolerably complete except the telson, the third consists of portions of the pereion, the pleon, and the telson, with traces of the caudal appendages. As is the case with so many of the fossils from the same prolific bed, the specimens occur as phosphatic casts only, no portion of the test having been preserved: these casts are, however, so sharp as to afford characters with quite sufficient distinctness to be available for specific description. As specimens of Isopods’ occur so rarely, and are usually so imperfect, the distinction of a new species by means of mutilated examples seems justifiable. Description.—General form slender, moderately convex trans- versely ; lateral margins of pereion approximately parallel ; cephalon about three-fourths as wide as the first segment of the pereion, rather _wider than long, rounded in front, posterior border with a median condyloid prominence. Hyes large, reniform, widely separated, directed obliquely outwards and forwards; extending backwards beyond the transverse mid-line of the cephalon. The three anterior segments of the pereion rather shorter than the succeeding four ; a sharp sulcus marks off a large epimeron on each segment. The pleon is about half the length of the pereion, and rather narrower ; it consists of five equal, short segments, the last of which is lodged in the sinus of the fourth. The telson constitutes the posterior half of the pleon, and is as wide anteriorly as the segment which sup- ports it: it narrows posteriorly and kas apparently no carina. The surface of all the segments may be seen under the lens to be pitted by large, widely separated, puncta (see Pl. VI. Figs. 4&5). The matrix in which the specimen is embedded shows a sharp cast of the uropodite, the basal joint of which has the inner distal angle prolonged into a spine more than half as long as the endopodite—a character which occurs in many Aigide: the endo- and exo-podite are broken; they were probably of moderate and of equal size. 196 E. Wethered—Structure of Jurassic Pisolite. Total length from 30 to 35 millimetres; width from 8 to 9 mm. _ Upper Greensand, Cambridge; Woodwardian Museum. | To one of the specimens (Figs. 5 and 7) Prof. Seeley attached as a -MS. label Squilla McCoyi, and this name is quoted by Mr. Jukes Browne in the list of fossils contained in his paper ‘On the Cam- bridge Gault and Upper Greensand’ (Q.J.G.S. May, 1875). The subsequent occurrence of two other specimens has enabled me to determine that the fossil so named is the pleon of the Isopod now described. Palega McCoyi is quite distinct from all other described fossil Isopods, although it bears considerable resemblance to several recent forms. I have provisionally referred it to the genus Palega, established by Dr. H. Woodward (Grou. Mae. 1870, p. 495). Some characters suggest a reference to the recent genus Cirolana, but the tribe to which it really belongs cannot be determined until the details of the cephalic and abdominal appendages are known; in the absence of this knowledge it is not possible to decide whether it should be referred to the Agide proper, or to the Cymothoide. With reference to these tribes, as regards living species, a most valuable and exhaustive series of articles, illustrated by numerous plates, have been published in Naturhistorisk Tidsskrift (Copenhag.), Bad. xii. xiii. xiv. 1879-84, ‘Symbole ad Monographiam Cymotho- aru,’ by J. C. Schicedte and Fr. Meinert. These authors also pub- lish a paper in the same series, ‘De Cirolanis A/gas simulantibus commentatio brevis,’ Bd. xii. 1879-80. DESCRIPTION OF PLATE VI. Figs. 1—7. Fic. 2. Palega McCoyi, Carter. Showing the cephalon (crushed), the pereion, and the anterior segments of the pleon. nat. size. aaa sly Me Be 30 Cephalon, first, and portion of second segment of pereion. nat. size. apy shee 45 a is The same specimen as Fig. 1, but enlarged. ponliidls a AS Fs Posterior portion of pereion, the pleon and ' the telson, with impression in the matrix of uropodite, nat. size. The same specimen as Fig. 7, but enlarged. Uropodite. enlarged. Restoration of entire form. - oN ~ v . ~ . IJ.—On toe Microscopic StructurE oF THE JURASSIC PISOLITE. By E. WetuHeren, F.G.S., F.C.8., F.R.M.S. (PLATE VI. Figs. 8—11.) HE specimens of pisolite which I have examined were obtained from two horizons, namely, the Coralline Oolite and base of the Inferior Oolite near Cheltenham. The pisolites are well known and have frequently been referred to by authors as fine types of oolitic granules, and in proof of this I may quote from Mr. H. B. Woodward’s last edition of his Geology of England and Wales. Speaking of oolite granules the author says (p. 281), “ When these E. Wethered—Structure of Jurassic Pisolite. 197 particles approach the size of a pea or bean, the rock is termed Pisolite, Pisolitic Limestone, or Pea-grit.” The Coralline Pisolite. For the specimens which I have examined from the Coralline Oolite and for information descriptive of the beds, I am indebted to Mr. H. B. Woodward, F.G.S., to whom I return my cordial thanks. The first specimens sent me were collected at Osmington, near Weymouth, from a bed 1 foot thick, and oceurring 6 or 7 feet from the base of the Coralline division, named “Osmington Oolite”’ by Blake and Hudleston.! The specimens consisted of dark brown calcareous spherules about the size of peas. They were loosely em- bedded in an argillaceous matrix in which there were also oolitic granules of the ordinary size and type. The sections of the spherules show a nucleus in each, but the structure of the surrounding material can only be studied through a microscope. Viewed through a low power the nucleus is observed to be enclosed by rudely concentric layers of innumerable minute tubuli. Examined by a half-inch object glass the tubuli are clearly defined. They measure about z;'s5 of an inch in diameter, and are remarkable for the extraordinary vermiform twistings and turnings which they exhibit, Fig. 9, Pl. VI. They appear to make up the whole mass; no skeleton fibre can be made out, and what spaces there are between the tubuli are filled with crystalline calcite. The only system exhibited by the tubuli, if system it can be called, is that they appear in aggregations, having a concentric tendency around an unoccupied space in the centre of each aggregation, and that the latter seem to interlace one with the other. The other specimens sent me by Mr. Woodward were collected at Sturminster Newton, from the bed No. 6a. mentioned by Blake and Hudleston.? The horizon is the same as ‘the Osmington pisolite, and the bed is described as consisting of “loose pisolite of large flattened concre- tions, 1 foot thick.” In shape and size the spherules are similar to those from Osmington, but they are lighter in colour. The micro- scopic structure is generally well preserved and coincides with the description given of the Osmington pisolite. Pisolite, or Pea-grit, from the Inferior Oolite. Pl. VI. Fig. 8. After examining the specimens of pisolite from the Coralline Oolite I turned to the Pea-grit, so well known as occurring at the bottom of the Inferiar Oolite in the Northern Cotteswolds. The greatest development is in the neighbourhood of Cheltenham, and the strati- graphical features of these interesting beds have been frequently referred to by geologists; among whom I may mention Sir R. Murchison, Mr. Strickland, Dr. Wright, Professor Hull, Mr. Lycett, Professor Buckman, Mr. Witchell, Mr. Etheridge and Mr. Lucy. 1 Quart. Journ. Geol. Soc. vol. xxxili. p. 265. * Loc. cit. p. 276. 198 E. Wethered—Structure of Jurassic Pisolite. Dr. Wright! divided the beds as they occur at Leckhampton near Cheltenham as follows, in descending order : “A. Brown, coarse, rubbly oolite, full of flattened concretions, cemented together by a calcareous matrix. aa L2ereet ‘©B. A hard cream-coloured pisolite rock made up ‘of flattened concretions of about the thickness of those in A... soo KO) *¢C. A coarse, brown, ferruginous rock composed ‘of large oolitic grains 20 Total ee ... 42 feet’’ Commencing the microscopic examination at the beds marked C by Dr. Wright, we see a limestone made up of granules and fragments of organisms, the spaces between being filled in with crystalline calcite. The organic fragments consist of spines of Kehini, Polyzoa, Crinoids, shells of Mollusca and Foraminifera, those of the Crinoids and Hchini are by far the most numerous. All the granules show a nucleus, but in some instances the original has become converted into crystalline calcite. The nuclei vary, indeed all the fragmentary remains of organisms mentioned as occurring in the rock may be said to serve. When the nucleus is a portion of a spine, then the shape is less spherical and is somewhat elongated. The granules are of two types; first the true oolitic granule distinguished by the concentric layers; second, spherules which vary in size from that of ordinary oolitic granules to that of a pea. In this latter type of spherule the nucleus is not surrounded by concentric layers of carbonate of lime, but by vermiform tubuli averaging about 53> of an inch in diameter (Figs. 10-11), but in some instances they are larger. The tubuli may be said to be arranged in layers or bands which are concentric with the nucleus. In some instances the tubes turn and twist about in a very remark- able manner, sometimes assuming a flat spiral form. Passing to the succeeding series of beds, marked B by Dr. Wright, we find the pisolite spherules? as large as peas (Fig. 8, Plate VI.), but often flattened. The typical Pea-grit is confined to one bed which averages about 4 feet 6 inches thick, and is best studied at Cleeve Hill. It is a mass of the spherules, which are firmly cemented in the matrix. On exposure to the action of the atmosphere the matrix is removed and the spherules then stand out in relief and after a time become detached. On examining some of these with a magnifying glass a vermiform structure may be noticed In some instances. Thin sections made from this typical bed show the nucleus in the spherules to be surrounded by the same tubuli as represented in Figs. 10 and 11, but if anything they are more vermiform. Some of these spherules, however, show layers and spaces not occupied by that type of tubuli, and when these are not filled with crystal- line material, minute tubuli are seen which correspond with those in the pisolite from the Coralline Oolite. ? Quart. Journ. Geol. Soc. vol. xvi. p. 7, 1860. ' * T use the term spherule for the pisolites and granule for the ordinary oolitic orms. EE. Wethered—Structure of Jurassic Pisolite. hog INFERENCE. I now come to the inference which is to be drawn from the observations I have made. ‘The first conclusion, which cannot be disputed, is, that we can no longer regard the pisolites as a form of concretionary oolitic structure. The so-called pisolite granules are really formed by the growth of an organism around a nucleus. As to the determination of that organism the similarity to the genus Gir- vanella is at once suggested. This organism was first described by Professor A. Nicholson and Mr. R. Etheridge, jun.,' and has since been more fully referred to by Professor Nicholson.? He remarks, “This curious fossil occurs in great numbers in the lime-formation of the rock,” the Ordovician limestone, “and presents itself in the form of small rounded or irregular nodules which vary in diameter from less than a millimetre to more than a centimetre. The larger examples show a distinctly concentric structure, visible even to the naked eye, but the most powerful lens fails to show any obvious internal structure in fractured or weathered surfaces. Examined microscopically the nodules of Girvanella are seen to consist of exceedingly minute circular tubes, endlessly contorted and bent, and twisted together in loosely reticulated or vermiculate aggregations.” This description of the microscopic structure of Girvanella problematica, the one species of the genus mentioned by Professor Nicholson and Mr. Etheridge, jun., corresponds very closely with the structure of the Coralline pisolites, and with the minute tubuli in some of the Pea- grit spherules at the base of the Inferior Oolite. A comparison of actual specimens confirms the similarity, and I have no hesitation in referring the Coralline pisolites to the genus Girvanella. Nor do I find sufficient evidence to warrant me in making a new species. It is true that the majority of the tubes are smaller than those in G. problematica, and that Professor Nicholson makes no reference to a nucleus around which they congregate. Now, the first portion of a Jurassic Girvanella spherule to undergo change is the nucleus. In some specimens we find simply crystalline calcite into which the original nucleus has been converted. The Silurian rocks, in which Girvanella was first discovered, are so much older than the Jurassic Oolite that it is not surprising to find the original nucleus changed into crystalline calcite. In the specimens which I have examined of G. problematica there seems to me to be undoubted signs of a nucleus, and I therefore do not see my way to make the absence of a clearly defined nucleus in the Silurian forms the reason for proposing another species of those in the Coralline Oolite, but it is possible that at some future time evidence may be obtained which would warrant that course being taken for reasons apart from the nucleus. With some of the spherules of the Pea-grit the matter is different. The larger well-defined tubuli represented in Figs. 10 and 11 are wanting in the Coralline forms, and I therefore propose to give them the name of Girvanella pisolitica. It is a question whether 1 Mon. Sil. Foss. Girvan, pp. 22-3. pl. ix. 2 Geou. Mae. N.S. Dec. ILI. Vol. V. p. 22, 1888. 200 S. S. Buckman—On Jurassic Ammonites. two species should not be made out of the Pea-grit forms, on account of both the minute tubuli and the larger type occurring in the same spherule. For the present, however, I do not see my way clear, as it may be that the two forms are associated together in the same spherule. As to what known organisms Girvanella should he referred is a matter which seems to me to be one of considerable difficulty. Professor Nicholson and Mr. R. Etheridge, jun., referred it to the Rhizopoda and regarded it as related to the arenaceous Foraminifera. From this view Professor Nicholson, in his later communication, sees no reason to depart (loc. cit. p. 23). Girvanella pisolitica (new species), Plate VI. Figs. 10 and 11. This species occurs in the form of flattened spherules varying in size from 1 to 3%; of an inch in greatest diameter (Fig. 8, Plate VI.). In the centre of each spherule there is a nucleus which is surrounded by calcareous tubuli (Figs. 10 and 11) with well-defined walls, and averaging about ;3> of an inch in diameter, though some are smaller. In some instances, more especially in the larger spherules, the tubes bend and twist about in a truly vermiform manner, often assuming the form of a flattened coil. It differs from G. problematica inasmuch as the tubes do not occur in aggregations, and are more concentric around the nucleus. The tubes are also branching and are larger than those of G. problematica. DESCRIPTION OF PLATE VI. Figs. 8—11. Fic. 8. Spherules of Girvanella pisolitica from the Pea-grit near the base of the Inferior Oolite, Cheltenham. Natural size. ; Hae, Portion of Girvanella problematica from a Coralline Oolite spherule. x 68 iam. Fie. 10. Gérvanella pisolitica, shown in section, from near the base of the Inferior Oolite near Cheltenham. x 40 diam. (not 50 diam. as erroneously marked on the plate). Fie. 11. Another spherule of Girvanella pisolitica from the Pea-grit near Chelten- ham. x 380diam. Shows a joint of a Crinoid as a nucleus. IJI.—On Jurassic AMMONITES. By S. S. Buckman, F.G.S. AMMONITES SERPENTINUS (Reinecke), and Ammonires STRANGE WAYSI, Sowerby. N a former communication (Grou. Mag. Dee. III. Vol. IV. No. 9, p- 896, 1887), when pointing out how Reinecke’s Amm. serpen- tinus had been misunderstood, I gave as a synonym, but with a query, Sowerby’s Amm. Strangewaysit. As I have, since then, examined the type-specimen of the latter species contained in the collection of the Natural History Museum, and as Mr. E. Walford kindly forwarded me for my determination a capital specimen from Byfield, I have been able to satisfactorily settle the identity of these forms. Except being evolute carinate Ammonites, the two species have hardly a feature in common. S. S. Buckman—On Jurassic Ammonites. 201 Harpoceras STRANGEWAYSI (Sowerby). 1822. Ammonites Strangewayst, Sow. Min. Conch. pl, 254, figs. 1 and 3. 1885. Harpoceras serpentinum, Thompson (non Reinecke), Upper Lias; Journ, Northampt. Nat. Hist. Soc. vol. ii. p. 309, pl. 1, fig. 1. Discoidal, compressed, hollow-carinate. Whorls flattened, orna- mented with genuine sickle-shaped ribs, which, though less con- spicuous in size on the body-chamber, are there more distinctly bent. Ventral area marked by the prolonged forward sweep of the ribs, and surmounted by a well-marked hollow-carina. Inner margin almost upright, neither concave nor convex. Umbilicus shallow and open. Inclusion, with the body-chamber present, one-third. Termination of mouth-border partly visible, showing that it is plain, and curved like the ribbing. Aperture, oblong. The above, taken from Mr. Walford’s specimen, differs in some particulars from Sowerby’s description ; but then neither Sowerby’s figure, nor his description, agree with the original specimen. The umbilicus is drawn considerably too large; the inner margin— “oblique flattened surface which forms the inner edges of the whorls ”—which Sowerby emphasizes so particularly, is by no means slanting, but is nearly upright, and the sectional view which he _ gives is quite incorrect. The ribs, too, are not drawn with sufficient bend ; they are truly of the shape of a sickle, with the inner portion quite straight and a marked bend at the middle. The indications of suture-lines are correct enough in Sowerby’s figure, and his specimen shows that the lobes are exactly those of Harpoceras, as I described these in my former communication (p. 397). Harpoceras Strangewayst differs from Harp. faleiferum by its umbilicus being much more open—about one-fourth larger—its ribs not quite so strongly bent, and its inner margin almost upright instead of being undercut. Individual specimens of this species seem to differ in the coarseness of their ribbing. Sowerby’s example is more coarsely ribbed than his drawing would lead us to expect. Mr. Walford’s specimen came from the “ Fish-bed, Upper Lias, Byfield”; Mr. Thompson sent me a specimen from Bugbrook ; and I have a poor example from Trent near Yeovil ; Sowerby’s specimen came from Ilminster. The species seems to be unknown on the Continent. HILpocERAS SERPENTINUM (Reinecke). 1818. 5 inch, and most of the flakes are very much less, down to gy's0 inch, which seems to be the thickness of a large proportion of the fairly thin ones measured. The characteristic secondary cleavages, intersecting on the basal plane, are largely developed, though in many flakes they are con- siderably distorted, and are also frequently much masked by irregu- lar cracks and ruptures, these effects being due to the stress the 216 W. M. Hutchings—Ottrelite in North Cornwall. mineral has undergone during rock-movements. These cleavages are best studied on flakes isolated from the rock and separately mounted. The two most important of these secondary cleavages intersect on the basal plane at an angle of 120° or an approxima- _ tion to it. Many measurements give that angle exactly, while many more vary but little from it, though some diverge more markedly. Rosenbusch states that there is a third cleavage, less well developed, bisecting the obtuse angle of the other two. Cracks answering to this description may be seen in some flakes of the Cornish mineral, but they are few and not very marked. The French writers speak of a cleavage approximately vertical to one of those intersecting at 120°, and many cracks corresponding to this may also be seen in the mineral now under consideration. But it really does not seem possible to say that either is really a definite cleavage, or to be in any way certain concerning any third line of cleavage observable on the basal plane. The cleavage-cracks are nearly all quite vertical to the basal plane, and are seen on the lath-shaped cross-sections of the flakes as lines nearly always at right angles to the lateral boundaries, obliquity being rare and very slight. Most of the ottrelite flakes are intergrown with crystals of white mica, so that nearly all the narrow lath-shaped sections are seen to be united with one, or usually with two, flakes of the mica, one on each side, the individuals lying perfectly parallel, and in cases where the ottrelite is so cut that it extinguishes parallel to its length, the whole combination extinguishes together. The petrologists who have described the rocks of the Ardennes do not appear to have observed a similar intergrowth of ottrelite and mica. Gosselet considers (Htudes sur l’Origine de l’Ottrélite, Annales de la Société géologique du Nord, tome xv. p. 85) that in the rocks he studied the ottrelite was formed at a time after the phyllites were already fully developed as such. This appears to be equally the case in these Cornish slates, and it is quite evident on observation of structure and arrangement, that the white mica with which the ottrelite is intergrown was formed at the same time. It is in larger and much more definitely-bounded individuals than the main sericite of the rock. There are also crystals, apparently of the same genera- tion, but not intergrown with ottrelite. The dimensions of some of these average about 725 inch in length by half that width, in sections vertical to the base. This intergrowth with mica renders much of the optic examination of the ottrelite impossible in the slate direct. By pulverizing some of the rock moderately fine, a number of the thicker flakes may easily be detached from the mica, and are then easily separated out by means of a Sonstadt solution of sp.g. of about 3, most of the thinner flakes remaining suspended attached to mica. Material so separated is suited for optic examination, and, as above stated, for study of the cleavages, much of it being in sharply-bounded cleavage-fragments. In colour the Cornish mineral is more inclined to blue than the ottrelite of Ottrez. The characteristic pleochroism is strongly developed. The scheme is a=yellowish green, B=blue, y=pale greenish yellow. W. M. Hutchings—Ottrelite in North Cornwall. Pall Examined between crossed Nicols a large proportion of the lath- shaped cross-sections are seen to be twinned, but this twinning does not seem to be as pronounced as in some of the other occurrences of the mineral, there being mostly only two lamelle even in the thicker bits, and many flakes being quite untwinned. Many of these sections extinguish quite parallel to their length, but the greater number show an angle, which reaches as high as 20 degrees and over in some cases, though about 12 degrees is a more usual figure. The examination of selected, sufficiently thick, and untwinned fragments from the isolated material in convergent polarized light shows the emergence of a positive bisectrix on the principal cleavage-face of the mineral. The angle of optic axes is rather large. The optic-axial plain bisects the obtuse angle formed by the two best-developed secondary cleavages. As usual, the ottrelite is rich in inclosures, but is very much less crowded than in most other occurrences. The principal mineral inclosed: is rutile, in perfectly formed crystals for the most part, many being twinned both as “knees” and “hearts.” The largest crystals measure sayy inch, and they pass from this into the merest specks through all intermediate sizes. Other included matter is very small in amount, and mostly quite indeterminable in nature, with the exception of white mica which is frequent, and which is in many cases seen to occupy cracks and seams in the ottrelite. Many bits are also full of cavities of all shapes and sizes. Gosselet states that he was able to observe, around the individuals of ottrelite, zones which were very much less rich in microlites than ‘the rest of the rock. This is not the case in the Tintagel slate. The whole rock is very rich in minute rutile crystals; but though the ottrelite contains them in far greater abundance than does the sericite, there is no sign that it has impoverished the space just around it. No quantitative analysis has been made of the isolated material, but it has been tested as to its resistance to acids, and has been qualitatively analyzed, the results of these examinations confirming the optical and other evidence that the mineral is ottrelite. Specimens of the rock have been submitted to authorities in this country and on the continent, who also recognize the mineral as ottrelite. No doubt it will be found in other similar slates when search is made, as well as at Tintagel. The ilmenite of this rock is well worthy of remark. It is present in considerable amount in nearly all the phyllites examined, but is perhaps more abundant in this ottrelite-slate than in any other. It is pretty evenly diffused in little flakes and tablets. Some of it is in the form of the thinnest “‘micaceous ilmenite,” perfectly transparent, with rich brown colour, and there is every gradation of thickness and translucency, up to tablets which are perfectly opaque. The thinner and medium-thick flakes are all more or less ragged, but many of the thicker tablets show more 218 W. M. Hutchings—Ottrelite in North Cornwall. definite boundaries, and indications of crystal faces at the edges. The average diameter of the flakes is about ;45 inch, and the thickness of the opaque ones ranges between 33455 and yoyo inch. Like the ottrelite, the ilmenite lies in all directions with regard to the cleavage of the slate, but a considerable majority of the flakes are approximately parallel to it. A large part of this ilmenite is reticulated, in varying degree, with sagenitic rutile. Among the thinner transparent flakes all degrees may be seen, from such as show a wholly unbroken brown colour, to others which are so finely meshed with delicate interlacing lines of rutile, that only a high power suffices to display the structure ; and there are, finally, bits of sagenite in the network of which no trace of ilmenite is seen. Thicker plates of ilmenite also often show a. development of sagenite, while many show only a line here and there. Such of them as are still thin enough to be at all translucent frequently show indications, in strong light and under high power, that a little thinning would expose complete reticulations. Rénard has devoted considerable study to similar occurrences of ilmenite in rocks of the Ardennes. In a paper published in 1884 (Recherches sur la Composition et la Structure des Phyllades Ardennais, Bulletin du Musée Royal de Vhistoire naturelle de Belgique, tome iii. pp. 231-268) he described in detail, and figures the “phyllade 4 ilménite des Forges de Ja Commune.” The occurrence in this case is clearly of the same nature as in the Cornish slate, this being borne out by sections of the Belgian rock which I have examined; the difference being that in the latter the flakes are a good deal larger, while the amount present is very much less, as is also the proportion of it which is transparent or in which sagenite is developed. Rénard was at great pains to isolate some of the mineral and prove chemically that it is ilmenite. In the Cornish rock, in face of the large amount of transparent brown flakes, such chemical proof would scarcely be called for; but it is all the better that Rénard carried it out, inasmuch as it does not seem practicable to isolate the much smaller flakes and tablets of the Tintagel slate. No better material could be desired than these North Cornish phyllites for the study of these highly interesting microscopic sagenites and their combinations with ilmenite; and in view of the large amount of very thin, thoroughly transparent flakes so com- bined, I have been in hopes that by careful study of them some light might be thrown on the question as to how the combination ought to be regarded ; whether the sagenite is a secondary product resulting from the decomposition of the ilmenite; whether the two have been originally formed together as now seen; or whether, in any cases, the intervening ilmenite has resulted from an alteration of the rutile, the occurrence of alterations of rutile into ilmenite having been demonstrated by V. Lasaulx. The first of these alternatives is that which most readily suggests itself on first examination of the minerals; and it might seem to derive some support from Cathrein’s observation that ilmenite dis- solved in acid frequently leaves a residue of extremely minute W. M. Hutchings—Ottrelite in North Cornwall. 219 needles of rutile. In the course of an investigation of the ilmenite and leucoxene of certain schists from Wildschonau in the Tyrol (Zeitschrift fiir Krystallographie u. Mineralogie, Band 6, pp. 244— 256) he found that ilmenite, which was perfectly homogeneous and opaque under the microscope, left a considerable amount of such residue on solution. By using hydrochloric acid for this purpose, he was able to detect combinations of the most delicate needles of rutile in networks and “gratings ” of sagenite. He does not say whether he himself came to any conclusion as to the primary or secondary nature of these interpositions, which appear to correspond with what is so well seen in the thin ilmenite flakes of the Cornish slate; neither does Rénard, so far as I am aware, express any opinion on this point, nor do I know of any other authority who has done so. After long and careful examination of these forms I do not find it possible to say that there is much evidence one way or other, but consider that on the whole it appears most probable that it is a case of original inter-crystallization. The study, under high powers, of the thinnest, most transparent flakes in every degree of reticulation, seems to show that in all cases the rutile of the sagenite is so very sharply marked off from the ilmenite that the idea of a chemical change going on between the two is not easily entertained. The whole question as to the mode of origin of these ilmenite flakes is one of great interest. It seems clear, from the manner of occurrence in the rock, that like the ottrelite they were produced at some period posterior to the formation of the sericite-phyllite as such, and there is much evidence that they also have been much torn and broken up at a still later period. Calcite is present in this slate in noticeable amount in the form of grains and small patches irregularly diffused all through it. There are a few small patches of pale chlorite, of which it is to be remarked that they are quite free from the microlites of rutile, so abundant in the rest of the rock. Tourmaline in perfect hemihedral crystals is well represented, these crystals measuring in most cases soo inch in length. They appear all to lie with their long axes parallel to the plane of cleavage of the slate. This slate is so completely metamorphosed that nothing whatever can be detected which could be referred to the original clastic material out of which it has been formed, except a few crystals and rounded grains of zircon. Roofing-slates from other quarries of the district all resemble that just described in general structure and composition, though, with the exception of the fundamental basis of sericite, the amounts of the various minerals present vary a good deal. Thus ilmenite is much more abundant in some than in others, and in some cases does not show any sagenite. The latter is present in numerous and fine examples, however, in the Delabole slates. Garnets are plentiful in some slates, as at Delabole. The other phyllites, not fit for roofing-slates, show rather more 220 C. Davison—Secular Straining of the Earth. variety of composition. Chlorite is much more abundant in some of them. Ilmenite is almost universal, and in many cases is as abund- ant and as full of sagenite as is the ottrelite-slate. Garnet is very abundant in some cases, and most of all in specimens taken from “near the contact with one or other of the igneous rocks described in a recent paper. This garnet is all colourless, or very nearly so. It is in the form of. very small irregular grains with only here and there a solitary case of any crystal-form. Tourmaline is much increased in amount near the contacts, and is in some cases the main constituent after the sericite. Rutile is present in large amount in all the phyllites of the dis- trict, as minute crystals, and, in some cases, also in large grains and tablets. In none of the many specimens examined by me, have I come across any ottrelite, except in the one case described. It is hardly likely that it is limited to the one particular quarry, but I have not been so fortunate as to find it anywhere else. There are several beds of black, shaly rock in among the sericite phyllites at various points. They are almost wholly siliceous in nature, very fine-grained quartzites cemented and veined with in- filtrated silica and permeated through and through by fine carbon- aceous matter. These rocks contain but little of any other minerals, and do not present any special interest. VIII.—On tue Securar Srraintinc oF THE Harta. I.! By Cuarues Davison, M.A., Mathematical Master at King Edward’s High School, Birmingham. yh early as the times of Descartes (1668) and Newton (1681), the “settling and shrinking of the whole globe after the upper regions or surface began to be hard,”* was held a sufficient cause for the formation of mountain-chains. Following the growth of our knowledge of mountain-structure, the contraction theory has been rediscovered several times in the present century. It has been worked out in great detail by Elie de Beaumont, Prevost, Delabeche and others; but, above all, by J. D. Dana, the real founder of the theory, in an admirable series of papers extending over the last forty-two years. ' Read before the Birmingham Philosophical Society on Feb. 14, 1889. In this paper I have attempted to give an account of part of a paper ‘‘ On the Distribution of Strain in the Earth’s Crust resulting trom Secular Cooling, etc.,’’ read before the Royal Society on May 5, 1887 (Phil. Trans. 1887, A. pp. 231-242). The reasoning in ch. xi. of Mr. T. Mellard Reade’s work on ‘The Origin of Mountain Ranges”’ (1886) shows that he had previously perceived the existence of a surface of zero- strain in the earth’s crust, separating an outer region of crushing from an inner region of stretching. In his well-known paper, ‘‘On the Formation of Alpine Valleys and Alpine Lakes’? (Phil. Mag., Feb. 1863, 4th ser. vol. xxv. p. 97), Mr. John Ball arrived at the conclusion that folding by lateral pressure diminishes as the depth from the surface of the earth increases, until it becomes insensible. * Brewster’s ‘* Memoirs of Sir Isaac Newton,’’ vol. ii. Appendix 4; Nature, vol. XXXVill. p. 30. C. Davison—Secular Straining of the Earth. 221 Leaving its details out of account, the fundamental idea in the contraction theory may be stated as follows: The whole earth was originally at a high temperature throughout, its present distribution of temperature being the result of cooling since the initial epoch. The surface of the earth has now practically ceased to cool, and the interior at and below a depth of two or three hundred miles has not yet begun sensibly to lose its heat. The intermediate layer in cooling contracts, and the outermost crust, being deprived of its support, is crushed and folded by the tremendous pressures thus brought into action. The ridges and wrinkles, into which the crust is thrown, constitute our mountain-chains. It is curious that, until recently, attention has been wholly concentrated on the behaviour of the outer crust with respect to the cooling layer beneath it, and that the behaviour of the cooling layer itself with respect to the uncooled nucleus within has passed unnoticed. Taking this latter relation into account, however, it will be found that new light is thrown upon several points of the theory, and especially on the comparatively superficial nature of the mountain-making forces. I shall assume in this paper the truth of the doctrine, which recent researches agree in indicating with a high degree of proba- bility, that the earth is practically a solid body; also of Sir W. Thomson’s celebrated investigation on the secular cooling of the earth. Further, in order to simplify the problem, I shall suppose the earth to be a sphere and its surface perfectly smooth. Taking the initial temperature of the earth at 7000° F., and the average rate near the surface at which the temperature increases with the depth at 1° F. for every 51 feet, Sir W. Thomson shows that the date at which the earth solidified cannot have been less than 20 million, nor more than 400 million, years ago, that it was probably not far from 100 million years ago. In his well-known paper, he gives a curve which repre- sents the temperature at different depths, and which is reproduced in the accompanying figure. The depths from the surface are repre- sented by lengths measured from A along the line as. The tempera- ture at the depth an is represented by the length of the line np drawn at right angles to as. If lines like np be drawn from every point in aB, and if each line be made proportional in length to the temperature at the corresponding depth, the other ends will all lie on the curve apc. At the depth represented by as, about 150 miles, the temperature is very nearly the same as it must be in the entire mass below. At a subsequent date, every point, through cooling, is at a lower D B 222 C. Davison—Secular Straining of the Earth. temperature. The state of temperature may then on the same scale be represented by the curve ace. The temperature corresponding to the depth an is now represented by the line nq instead of NP, so _that the amount of heat lost in the interval is represented by the length of the line ap. If we now suppose the line nap to start from Ap and to move downwards, keeping parallel to itself, the part op, at first zero increases for a certain distance, until it becomes a maximum, and then it decreases until the line nap reaches the position BEC, where it is practically again zero. Since the rate of cooling is proportional to the amount of heat lost in a given time, it follows that this rate is zero at the surface, that it increases as the depth from the surface of the earth increases, until it is a maximum, after which it decreases, becoming insensible at a depth of two or three hundred miles. Ifthe time since the earth solidified be 100 million years, Prof. G. H. Darwin has shown! that the depth at which the rate of cooling is greatest is about 53 miles. He has shown also that this depth increases in proportion to the square root of the time, that is, at four hundred million years the depth will be twice as great as this, three times as great at nine hundred million years, and soon. At the initial epoch, it coincided with the surface of the earth. If a sphere, having the same centre as the earth, pass through the point at which the rate of cooling ceases to be sensible, it will include within it the whole mass of the earth which has not yet begun to lose its heat, the ‘uncooled nucleus,” as it has been called above. The rest of the earth, constituting the ‘“ cooling layer,” may be supposed to be divided up into a very great number of very thin shells by spherical surfaces all having the same centre as the earth. Hach shell must be imagined so thin that the rate of cooling varies by an infinitely small amount between the inner and outer surfaces of the shell. Let us now consider the consequences of the method of cooling described above; and, first, in the lowest shell of the cooling layer, that next to, and surrounding, the uncooled nucleus. In a given time, this shell loses a definite, though small, amount of heat, in consequence of which it must contract in volume. If the shell were isolated, it would also contract in radius, by an amount proportional to the loss of heat. But this is prevented by the presence of the nucleus within. The contraction can therefore be accomplished only by the shell stretching over the nucleus, at the same time diminishing in thickness. The next succeeding shell is stretched in a similar manner. If the loss of heat were the same as in the first shell, both shells would be stretched by very nearly the same amount. But it loses more heat in the same time, for the rate of cooling at first increases from the nucleus outwards. The second shell is therefore stretched more than the first. In like manner, the third is stretched more than the second; and this is the case with every shell to very nearly as far as the surface where the rate of cooling is greatest. 1 Nature, vol. xix. p. 313. C. Davison—Secular Straining of the Earth. 223 Above this surface a change takes place. In this part of the earth’s crust each shell in a given time loses less heat than the shell below it, and consequently undergoes less stretching. The stretching thus decreases gradually and continuously towards the surface of the earth ; and it may be shown that at a certain point it vanishes altogether. To do this, we must consider the shells close to the surface of the earth. The outermost shell of all is not losing any heat. The layer between it and the nucleus, by cooling and contracting, is diminished in thickness, and tends to leave the shell unsupported. But, immediately this takes place, enormous lateral pressures are developed by the attraction of all the earth’s mass within; and the outermost shell is crushed and wrinkled until it rests completely on the mass below. In the same way, the shell next below the outer- most is crushed and folded, but not to so great an extent, for it does lose a certain small amount of heat, and the contraction due to this brings it a little nearer the mass on which it is obliged to rest. In the shell below this, the loss of heat is still greater (for the rate of cooling increases from the surface downwards), and the amount of folding still less, and so on. Thus the folding and crushing of the shells gradually and continuously diminish as the depth from the surface increases. We have now the following state of things. From the surface of greatest rate of cooling, stretching gradually diminishes outwards. From the surface of the earth, crushing and folding gradually diminish inwards. At some point between the surface of the earth and the surface of greatest rate of cooling, there must be a shell which is being neither stretched nor crushed. We may call it there- fore the “surface of zero-strain.” This surface plays an important part in the physical history of the earth. If the contraction theory be true, our loftiest mountain- ranges must be formed principally, perhaps entirely, of the material in the comparatively thin layer of rock outside it. Our earthquakes and volcanic eruptions probably originate at points above the surface of zero-strain. It would therefore be an interesting and important problem to determine, if we could, the depth of the surface of zero-strain; but, in the present state of our knowledge, it is impossible to do this accurately. Assuming, however, that the coefficient of dilatation and the rate of conductivity are the same at all temperatures, that the surface of the earth is a sphere, and that the stretching or folding of any shell is uniform all over that shell, I found, by an approximate method which it is hardly necessary to describe, that the surface of zero-strain was, or more probably will be, at a depth of five miles after an interval of 174,240,000 years since the earth solidified. This depth, on account of the method of calculation employed, is too great by a fraction of a mile, but we shall probably be well within the limits of error if we put it at between four and five miles. 1 This period was adopted in order to simplify the calculations, and is well within the limits given by Sir W. Thomson. 224 R. M. Deeley—Boulder Clay in Derby. At the same time and on the same assumptions, the depth of the surface at which stretching is greatest would be about 72 miles, this surface being less than a mile below the surface of greatest rate of cooling. We may sum up the results obtained for this period as follows, assuming the surface of the earth to be smooth and spherical: Folding by lateral pressure is greatest at the surface. It diminishes as the depth increases until, at a depth between four and five miles, it vanishes. Below this depth, folding by lateral pressure gives place to stretching by lateral tension, and the stretching increases as the depth increases until it is a maximum at a depth of about 72 miles. Below this, again, the stretching begins to decrease, and it continues decreasmg, until it practically vanishes at a depth of about 200 miles. If the contraction theory be true, the most important evidence which the surface of zero-strain gives us is that relating to the extremely superficial nature of the forces which produce our mountain-ranges. Some geologists have regarded the slight depth of the surface as a strong argument against the theory. It seems to me that they are somewhat hasty in coming to this conclusion, that they do not take sufficiently into account our utter ignorance on many important points. It cannot be denied that the theory is surrounded with great and serious difficulties, but I submit that there is a difference between objections which cannot be met and difficulties which have not yet been solved; and I cannot help thinking that these difficulties, if treated as subjects for future investigation, will sooner or later be removed. The contraction theory is attractive not only from its beauty and its simple grandeur. It explains so many phenomena in the evolution of mountain-chains ; so many apparently unconnected facts are grouped together by its guidance; that the reasons must be weighty indeed which shall lead us to reject it. 1X.—An Exposure or Mippir anp Newer PLEIsTtocenE BovuLpER Cray In Dersy. By R. M. Dzetey, F.G.S. OME very interesting deposits of Pleistocene age have lately \-) been exposed on the Burton Road, Derby. The road rises on the north side of Mill Hill, and near the top, at the height of 260 feet, cuts into a mass of Boulder-clay, which is, or was, well shown in the cuttings for the new roads leading into Byron Street. Another outlier of the same clay is exposed in Littleover Lane to the south- west. The main mass of the deposit cut into on the Burton Road is ared morainic clay with boulders; apparently a subaerial moraine subsequently modified by the passage over it of land ice. Unlike the tough, silty, red and blue aqueous Boulder Clays so plentifully spread over the Midland counties, it shows little or no signs of aqueous action. Sometimes it has a banded or streaked appearance, but this seems to be due rather to a crushing or pressing-out action than to original conditions of deposition. In this respect it much R. Ml. Deeley—Boulder Clay in Derby. 295 resembles many of the morainic deposits of the Lake District and North Wales. Although the matrix is chiefly finely broken up Keuper Marl and Coal-measure rock, there are occasional beds of what appears to be torrential sand and gravel much disturbed by subsequent ice action. Large boulders of Upper Carboniferous rocks, together with quartzite pebbles, probably derived from the Bunter Pebble Beds, are abundant, but Carboniferous Limestone is rather scarce. Flints are numerous and sometimes of large size. They are scattered throughout the whole depth of the deposit, not merely intruded into the surface portions. I have elsewhere pointed out! that in the Midlands flints are absent from the thick deposits of Older Pleistocene Boulder Clay and sand, but appear in great abundance in the clays and sands of Middle Pleistocene age. Associated with the Older Pleistocene Boulder Clays there occurs a thick deposit of sand, the Quartzose Sand, the false bedding of which indicates powerful currents from the north-west and south-west. The absence of flint from these deposits has a peculiarly interesting bearing upon the question of where the flints in the clays and sands of Wales, Cheshire, and Lancashire came from, and also when they were carried to the positions they now occupy: In Older Pleistocene times, when, as we have seen, the currents were favourable for the transport of flints from Ireland, flints were certainly not brought in any quantity into the Trent Valley. At least I have only found them in deposits of this age near the surface, into which they have no doubt been subsequently introduced. In Middle Pleistocene times, when the ice-flow was from the East or N.N.E., great quantities of flint and chalk were carried into the Trent Valley; for flints form a considerable pro- portion of the Chalky Sand even in the extreme north-westerly portion of the area; indeed they may be found in the Chalky Sand where it passes through the Biddulph Pass into the Cheshire Plain ; but the nearer we approach the hypothetical Irish source, the more scarce they become. I do not mean to assert that no flints have crossed over from Ireland; but the weight of evidence points strongly to the conclusion that the vast majority of the flints in the Boulder Clays and sands of North and South Wales came from the east of England during the Middle Pleistocene epoch. The presence of flint in the Burton Road and Littleover Boulder Clay, therefore, favours the assumption that the deposit is either of Middle or Newer Pleistocene age. Fortunately a deep excavation in the road, after passing through the red morainic clay, entered a couple of feet of blue silty clay full of rounded grains and pebbles of chalk. This deposit, which was clearly typical Chalky Boulder Clay, rested directly upon Keuper Marl, and was separated by a sharp line from the red clay above. Another shaft close by passed through clean-bedded Middle Pleistocene sand. Both the litho- logical and stratigraphical evidence, therefore, points to the con- clusion that the upper clay is the Later Pennine Boulder Clay.’ 1 Q. J. G.§. Nov. 1886. 2 That Mr. A. J. Jukes-Browne has misunderstood my argument concerning the DECADE III.—VOL. VI.—NO. Y. 15 226 Notice of Memoirs—The Mineral Wealth of Queensland. As I have recorded the presence of this deposit in many places in the neighbourhood of Derby, it is very satisfactory to find it resting in considerable masses upon, and separated by a sharp line of demarcation from, the Chalky Boulder Clay. It is evident from the great quantity of flint which exists in the Newer Pleistocene Boulder Clay and River Gravels of the Derwent Valley, at and below Derby, that the small patch of Chalky Boulder Clay on the side of Mill Hill is merely a remnant of a great mass of the same deposit which once partly choked up the Derwent, Trent, and other valleys, outliers of which are to be seen at Chellaston, Doveridge, and Hanbury Wood End. 39, CaversHaAM Roap, Kentisu Town, N.W. IN(OEMCCIaS) | (ena IMrssWiOorsiss T.—Tae Mineran Wraith oF QuennstanD. By R. L. Jack, F.G.S., F.R.G.S., Government Geologist. Brisbane, 1888. 8vo. pp. 71. With Map showing position of the Mineral Fields. NHIS book, written at the request of the Hon. the Minister for | Mines and Works, gives a resumé of the mining statistics of the Colony, with an account of the mineral fields that have been or are being worked, of the geological formations in which they occur, the methods of working and of reducing them where the latter is done on the spot, as well as a list of the minerals associated with them, and a table of localities where minerals yet undeveloped are known to exist. In 1887 about 400,000 oz. of gold were raised, of which less than 25,000 were of alluvial origin, the remainder being obtained by crushing stone containing from one to two ounces to the ton. The wealthiest gold field is the Charters Towers, for which the returns given for 1887 are alluvial 317 oz., reef 151,060 oz. obtained by crushing 83,292 tons of quartz. The gold here is associated with pyrites, galena, and zinc-blende, and the yield per ton shows a slight increase at the deepest levels, the lowest of which is now 1400 ft. Gold occurs in most parts of the Colony, but as far as at present known only in paying quantities near the coast in the southern half, while in the northern or tropical divison in the interior as well. The most remarkable mine is that of Mount Morgan in the Rock- hampton District. The Mount is a dome-shaped hill 1500 ft. above sea-level and 500 above the surrounding table-land, of which the Newer Pleistocene Boulder Clays of Lincolnshire is evident from the following passage in his letter, which I quote. Referrimg to my short paper in the Gzox. MacAazine for October, 1888, he says, ‘‘ He suggests, however, that some of the clays classed by me as Newer Glacial may really be older than the Chalky Boulder Clay, and he apparently finds great difficulty in accepting the occurrence of such Newer Glacial beds at elevations approaching 400 feet.’’ My greatest difficulty, distinctly stated, was the supposed ‘‘ marine aspect of the high level, brown, Boulder Clays.” All Boulder Clays are certainly not marine, frequently not even aqueous. Reviews —Prof. A. K. von Zittel’s Palichthyology. 227 rocks belong to the Carbonifero-Permian series, and are intersected in every direction by dykes of dolerite, rhyolite, etc. “The upper portion of Mount Morgan consists of a deposit varying from red and brown hematite on the one hand to a frothy, spongy cellular siliceous sinter on the other. Fine gold is disseminated throughout the mass,” it has averaged of late 7 oz. to the ton, is absolutely free from silver. The mining operations are simply quarrying, and the gold is extracted by chlorination. The mine is estimated to be worth £16,000,000, while Messrs. Morgan Bros., the original pro- prietors, who gave their name to the Mount, are said to have sold the 640 acres it covers for less than £300. The amount of silver obtained in 1887 was over £120,000 in value, chiefly from galena, though in the Ravenswood silver-field the surface yielded lead carbonate giving as much as 300 oz. of silver to the so lower levels of galena giving 20z., while at a depth of 650 ft. “the shaft bottomed on an “antimony and copper ore some- what resembling tetrahedrite in composition, but containing from 200 to 5000 oz. silver to the ton.” The tin, produced chiefly by mining and crushing porphyry, quartzite and chlorite dykes, though a considerable quantity is obtained from alluvial deposits, was valued at over £220,000 in 1887. Copper is not worked to any great extent, though there are lodes of oxides, carbonates and sulphides, the latter containing in some eases both gold and silver in considerable quantities, “which, to quote the author, ““would be payable under favourable conditions,” meaning, we presume, proper facilities for carriage, for in one place he instances freight to England £1 per ton of ore, while the carriage to the port of shipment was £4 per ton. The other metals are mercury and cobalt, the ores of the latter are very rich, and promise to be very productive when the workings are extended. Antimony has been mined to a small extent. The Coal-fields extend over thirty thousand square miles, occur- ring in the Carbonifero-Permian and Jurassic systems. The quality is good in some of the seams, but in others the percentage of ash is high. The workings at present are few, in fact only 230,000 tons were raised in 1887. a5) Ash WW AE ae TN 2 ; I.—Pror. Dr. von Zirten on PALicHTuyoLoey. Kart A. von Zirret, HanppucH pERK PaLaontTotogizr. Papmo- zootoGigE, Band III. Lief. I. II. (R. Oldenbourg, Munich, 1887-88.) (Concluded from page 181.) TELEOSTEI. HE only modern synopsis of the Palzontology of the Teleostean fishes, previous to the publication of Dr. v. Zittel’s work, is to be found in Dr. Giinther’s “Study of Fishes” (1880); and as this is merely an outline, without details or references, the present 228 Reviews—Prof. A. K. von Zittel’s Palichthyology. “Handbuch”? supphes an important desideratum in Ichthyological literature. The description of the “ subclass” occupies pp. 252- 316, and is illustrated by 58 woodcuts. After an enumeration of the more general works upon the subject, and a preliminary definition, the six ‘‘orders” of Johannes Miller are adopted, and the extinct representatives of each noticed in succession from the Lophobranchii to the Anacanthini. The known fossil Lophobranchs are but few in number, and restricted to the Tertiaries. Of the Solenostomide an extinct repre- sentative (Solenorhynchus) occurs in the HKocene of Monte Postale ; and the common surviving pipe-fish (Syngnathus) is met with in the Oligocene of Monte Bolca and Croatia, and in the Miocene of Licata, Sicily. A Hippocampus-like fish with a caudal fin (Cala- mostoma) has also been described by Agassiz from Monte Boleca. The Plectognathi have a scarcely more satisfactory paleontological record, and only a few types, closely related to living genera, have hitherto been detected in the Tertiaries. Of the sun-fish (Orthago- riscus) Dr. v. Zittel rightly casts doubt upon Dixon’s supposed fossil jaw from the Chalk, which now proves to be the dentary bone of a turtle ;' but reference might have been made to the undoubted mandibles of Orthagoriscus discovered in the Oligocene of Belgium.” Diodon has a wide range from the Oligocene upwards, and there are some indications of closely-allied extinct genera in the Lower Tertiaries of Egypt, the Gironde, and Monte Postale. Ostracion occurs at Monte Bolca; and Balistes is supposed to be represented upon the same horizon by the extinct Protobalistum. Following Baron de Zigno, the author assigns two species to the latter genus, but Dr. Theodore Gill® has lately pointed out that a rearrangement is required, and that the so-called P. Ombonii forms the type of a very distinct genus to be henceforth termed Protacanthodes. Acan- thoderma and Acanthopleurus are the well-known Scleroderms described by Agassiz from the black slates of the Canton Glarus ; and, in default of a more certain position, the pharyngeal teeth named Ancistrodon (first determined as such by Dr. W. Dames) are pro- visionally placed as an appendix to the same group. The great order of Physostomi commences with the family of Siluride, and the earliest undoubted representatives of this remark- able division are recorded from the Hocene. One extinct genus (Bucklandium) has lately been noticed in the London Clay of the Isle of Sheppey ;* and a recent discovery of a nearly complete skull in the Barton Clay ° has confirmed the occurrence of the recent genus Arius in the English Middle and Upper Eocenes. The genera from the Pliocene of the Siwalik Hills, India, and from the Lower Tertiary of Padang, Sumatra, are also satisfactorily determined ; but the so- called Pimelodus from the Miocene of Hungary is based upon fin- 1 Proc. Geol. Assoc. vol. x. p. 276. 2 P. J. Van Beneden, Bull. Acad. roy. Belg. [8] vol. vi. (1883), p. 132. 3 Amer. Nat. 1888, pp. 446-448. 4 Grou. Mag. [3] Vol. V. p- 471; and Proc. Zool. Soc. April 2nd, 1889. © K. T. Newton, Proc. Zool. Soe. ‘April 2nd, 1889. Reviews—Prof. A. K. von Zittel’s Palichthyology. 229 rays which appear quite indeterminable, and probably do not belong even to the Siluroid family. Following the Siluride are the three typically-Cretaceous families of ‘‘Saurocephalide” (Saurodontide of Cope), Hoplopleuride, and Stratodontide. These, however, can only be regarded as pro- visionally defined, and the precise relationships even of the best- known genera are at present very doubtful. Portheus, Ichthyodectes, and Saurocephalus are typical representatives of the Saurocephalide : but, as Cope has already recognized,’ it is impossible to place Protosphyrena with these. The stated definition of the Hoplopleuride contradicts one point (“ Wirbelsiule verknochert”’) in the diagnosis of the “subclass Teleostei” on p. 252; and this contradiction is introduced to admit of the association of the early Mesozoic genera, Belonorhynchus and Saurichthys, with Dercetis and its allies of the Chalk. Such an association appears to the present writer most unnatural and unjustifiable ; for it must be remembered that in the dorsal and anal fins of Belonorhynchus the interspinous bones are very much fewer in number than the dermal rays*—a character unknown in any fishes higher than Crossopterygians and Acipen- seroids—while the maxilla of Saurichthys has lately proved to exhibit a palatal extension such as has hitherto been met with only in the Crossopterygian Polypterus.2 The Neocomian Saurorhamphus, it is true, is said to have possessed a persistent notochord, but more information is required concerning this fish. Leptotrachelus is probably a synonym of Dercetis, or at least is not separated by the usual diagnosis;* and in whatever family Hurypholis is placed, Enchodus must follow. Hurygnathus (Davis) is a synonym of the latter,° and the recent discovery of complete skulls has proved the stout bones so long described as premaxille (and thus named by Dr. v. Zittel) to be truly the palatine elements.° The amended “‘ Hypsodon” is identical with Pachyrhizodus;7 and next to Cimo- lichthys we might add Pomognathus,? removing it from p. 279. The Hsocide have few extinct representatives, so far as known, though there is much in their anatomy to suggest close alliance with some of the earlier Physostomi. The Notopteridz and Chiro- centridz also have no fossil representatives of importance ; but the enumeration of the succeeding Clupeide occupies nearly nine pages. Here Dr. v. Zittel places the typically Jurassic T’hrissops and Leptolepis, adopting a subfamily Thrissopina, and then three others—the Clupeina, Chanina, and Hlopina. A fine new figure of the head, opercular apparatus, and pectoral arch of Leptolepis is given; and there is some interesting information concerning the mandible both of this genus and of Thrissops. W.von der Marck’s wide separation of Sardinioides from Osmeroides is accepted; Scombroclupea follows 1 Bull. U.S. Geol. Surv. Territ. vol. ii. (1887), pp. 821-823. W. Deecke, Paleontogr. vol. xxxv. (1889), p. 129. Ann. and Mag. Nat. Hist. [6], vol. ii. 1889, p. 302. Proc. Geol. Assoc. vol. x. p. 319. Grou. Mae. [3], Vol. V. 1888, p. 472. Proc. Geol. Assoc. vol, x. p. 315, pl. i. figs. 5, 6. Ibid. p. 811. - 8 Ibid. p. 817. AIA a rk wD 280 Reviews—Prof. A. K. von Zittel’s Palichthyology. Olupea ; and Diplomystus is recorded, but only from the Green River Shales of Wyoming. The latter genus is now known also from the Cretaceous of Brazil! and Mount Lebanon,” besides from the Oligocene of the Isle of Wight.’ The fossil Salmonide are little known, and to the author’s account we would only add that the remarkable nodular concretions with Mallotus villosus, so well known from Greenland, are also met with in the Glacial Clays on the banks of the Ottawa River in Canada. The paleontological history of the Scopelidz and Osteoglosside is likewise scanty; and the only point of much interest in that of the Cyprinodontide is the occurrence of the now-existing tropical American genus Pecilia, in the Oeningen beds of Switzerland. Many representatives of the Cyprinide occur in freshwater Tertiary formations, but the majority are referable to existing genera; and Notogoneus, from the Green River shales of Wyoming, is the sole recognized fossil genus of Gonorhynchide (misprinted Ganorhyn- chide). The Murenide occur first in the Upper Cretaceous of Mount Lebanon ; and the Scombresocide, which conclude the Phy- sostomous order, are considered by Dr. v. Zittel to be also probably represented in the Cretaceous by Istieus and Rhinellus. The order of Pharyngognathi comprises three families with fossil representatives—the Pomacentride, Labride, and Chromide. To the first are assigned two extinct genera, Odonteus from Monte Bolea; and Priscacara from the Green River Shales of Wyoming ; and in the last are placed the Cretaceous genera Pycnosterinz, Omosoma, and doubtfully Imogaster. The Labride are represented chiefly by detached examples of the pharyngeal dentition in the Tertiaries ; and in addition to typical forms like Labrus and Nummopalatus, Dr. v. Zittel places here the remarkable Eocene Phyllodus and Eger- tonia. ‘The latter are also recorded from the Cretaceous, but Phyllo- dus cretaceus, Reuss, is not founded upon satisfactory evidence ; and Egertonia gaultina, Cornuel, from the French Gault, is very doubt- fully related to the Eocene fossils, and may perhaps be more satis- factorily compared with the palatine dentition of the Hlopine Protelops from the Turonian of Bohemia. The order Acanthopteri commences with the Berycide, having many extinct representatives. In addition to the ordinary species, Beryx includes numerous detached scales described under five or six generic names from the Plainerkalk of Saxony and Bohemia; and we would only remark that the English Chalk species mentioned (B. lewesiensis) now proves to be referable to Hoplopteryx.4 In the last-named genus must also be placed the so-called B. Zippei, of the dorsal fin of which the figure copied from Fritsch scarcely gives a correct impression.® The Lebanon fossil named Homonoius pulcher 1 E. D. Cope, Proc. Amer. Phil. Soc. vol. xxiii. (1886), p. 3. 2 Ann. and Mag. Nat. Hist. [6] vol. ii. (1888), p. 184. 3 Clupea vectensis, KE. T, Newton, Quart. Journ. Geol. Soc. vol. xly. (1889), pp. 112-117, pl. iv. * Proc. Geol. Assoc. vol. x. p. 327. > Of. L, Agassiz, Poiss. Foss. vol. iv. pl. xv. fig. 2. Reviews—Prof. K. A. von Zitiel’s Palichthyology. 231 is probably a Pycnosterina ;' and Platycormus appears to have more affinity with the Squamipinnes than with the Berycidz. Like the last family, the Percidz are also represented by many extinct species and a few extinct genera, but these appear to be restricted to Tertiary formations. The Glarus fossil, Acanus, is placed here as the result of Wettstein’s researches; and the recent genus Serranus ranges downwards to the Eocene of Monte Bolca. Of freshwater genera, the common Perca has a wide range in the European Tertiaries; and Smerdis is a common extinct form in the Eocene and Miocene. The Pristipomatide are separated from the Percid, and the London Clay Scignurus is assigned a place in this family. . Dr. v. Zittel’s account of the Sparidee is an interesting palzonto- logical lesson ; for the variation in the teeth of these fishes has led to the publication of innumerable names, which the ichthyologist soon recognizes as worthless and arising from ignorance of recent genera. Capitodus, Minster, is shown to be partly founded upon the anterior teeth of Chrysophrys, and partly upon the pharyngeal teeth of Cyprinoid fishes; most of the crushing teeth of Chrysophrys have been named Spherodus and Sparoides by fossil collectors ; and Trigonodon, Sismonda, is shown to be a synonym of Sargus. A new genus, Stephanodus, is founded upon broad cutting teeth with denti- culated edges, from the Upper Chalk of the Sahara; and associated with these fossils are round crushing teeth, which seem to demon- strate the Sparoid affinities of the original fish. The Squamipinnes, Scorpenide, and Teuthidide, are not of much paleontological interest; and, as Dr. v. Zittel remarks, the published information concerning the fossil Xiphiides is somewhat doubtful.? The Palzo- rhynchide form an entirely extinct family of older Tertiary age, and the author considers that Hemirhynchus is a synonym of Palgo- rhynchus, being originally founded upon an imperfect specimen. It is satisfactory, at last, to find no mention of Enchodus in a paleontological account of the Trichiuride; and Wettstein’s deter- mination of the identity of Anenchelum with Lepidopus is adopted, thus extending the range of this recent genus to the horizon of the Swiss Glarus slates. Of the Acronuridee the recent genera Acanthurus and Naseus are determined from Monte Bolca; and the little Calamostoma (Stein- dachner) from the same horizon requires a new name, not being the Calamostoma of Agassiz (p. 256). The Carangide are represented by extinct species of the principal recent genera in the Tertiaries; and a few (e.g. Platax) also occur in the uppermost Cretaceous. Of the Cyttide, Zeus has been found in the Miocene of Licata, Sicily, and there is an extinct genus, Cyttoides (Wettstein), in the Glarus slates. A good figure of the well-known Mene (Gasteronemus) rhombeus is given under the Corypheenide ; and the succeeding list of Scombride and Trachinide does not present much of interest, except the occurrence of the specialized 1 Proc. Geol. Assoc. vol. x. p. 329. 2 See Proc. Geol. Assoc. vol. x. p. 321. 232 Reviews—C. E. Beecher—On the Brachiospongide. Echeneis in the Glarus slates, as discovered by Wettstein. The Pediculati or Lophiide are still only known, among fossils, in the Eocene of Monte Bolca; and the Cottide, Cataphracti, Gobiide, and Blenniide, are soon enumerated, the only striking forms being the problematical Petalopteryx and Cheirothriz from Mount Lebanon. Among the Mugiliformes, the so-called Sphyrena Amici, of Mount Lebanon, is rightly omitted; but it may be added that both Calamo- pleurus and Cladocyclus are well known from the English Chalk,’ and Dictyodus does not pertain to this family, but to the Scombridee.? There is also some doubt concerning Apsopelix, Cope, for it is men- tioned both here and in the Stratodontide (p. 269). The Blochiide, with the single remarkable extinct genus, Blochius, from Monte Bolca, follow the Mugiliformes ; and the Aulostomi close the Acan- thopteran series. Of the important modern order Anacanthini, so few extinct forms are known that less than two pages suffice for their consideration. Both the Gadide and Pleuronectide range from the Hocene upwards, but much yet remains to be discovered concerning their ancestry and precise relationships. In conclusion, Dr. v. Zittel devotes twenty pages to a general ” summary of our knowledge of the distribution of fossil fishes in space and time; and this unique work of reference is thus made available for the Stratigraphical Geologist equally with the systematic Ichthy ologist. A. Surra Woopwarp. TI.—Bracuiosponcipm: A Memoir on a Group oF SILURIAN SPONGES. With Six Plates. By Cuartes Emerson Bexcuer. Memorrs or THE Prasopy Musrum or Yate Universiry, Vol. i. pt. 1. (New Haven, Conn., 1889. Imp. 4to. 28 pp.) ie peculiar sponges to which Prof. O. C. Marsh gave the name of Brachiospongia have been described and figured since 1838, but hitherto their structural characters have been unknown. Mr. Beecher has carefully studied the specimens obtained by Prof. Marsh, and, aided by this gentleman’s liberality, has brought out the present beautifully illustrated Memoir, in which the real nature of these sponges is satisfactorily shown. 'The sponges themselves— which sometimes reach to a foot in diameter—consist of an open cup-shaped, central body, from which a number of curved, tubular finger-like processes project. The sponge-wall is built up of spicules of the hexactinellid type, which do not appear to be cemented together, with the exception of those forming the dermal layer, which are apparently fused into an irregular quadrate mesh. There is considerable variety in the outer form and the number of the pro- jecting arms in different specimens, but Mr. Beecher has done wisely in regarding them as belonging to a single species, B. digitata, D. D. Owen, sp. Another hexactinellid sponge having a peculiar lobate or tuberous form and a stout wisp or rope of anchoring spicules is placed in a new genus Strobilospongia. These sponges have been 1 Proc. Geol. Assoc. vol. x. pp. 324, 325. 2 Dollo and Storms, Zool. Anzeiger, No. 279 (1888). Reports and Proceedings—Geological Society of London. 233 for the most part obtained in Kentucky and Tennessee, in passage- beds between the Trenton and Hudson River formations, apparently on the horizon of the Utica Shale, which in these States is not dis- tinctively developed as a bituminous shale, the same as in New York and Canada. There is a definite horizon in Franklin County, Kentucky, in which they are associated with beds of cherty limestone, the chert being restricted to the bands in which the sponges occur. Their condition of preservation is as a rule un- favourable, and much credit is due to Mr. Beecher for having finally determined their structural characters. ISIS OissyS) CNANb) J 1 VOCs (eis. —+>—_ GroLtocicaL Socitrry or Lonpon. T.—March 6, 1889.—W. T. Blanford, LL.D., F.R.S., President, im the Chair.—The following communications were read :— 1. “On the Subdivisions of the Speeton Clay.” By G. W. Lamplugh, Esq. Communicated by Clement Reid, Hsq., F.G.S. This paper gave the results of a long series of observations made during favourable opportunities at the cliff-foot and on the beach at Speeton from 1880 to 1889. The chief points brought forward by the author were as follows :— The sandy blue shales now seen in the cliff near Filey are not in place, but are erratics in the Drift, and most, if not all, of them are derived from the Lias. The bituminous shales with Belemnites Owenii, classified as Upper Kimeridge, extend upwards to the Coprolite-bed and the beds described as Portlandian by Prof. Judd, having been wrongly placed in this part of the section. No unconformity is traceable at the Coprolite-bed, or at any other horizon, between the Jurassic and Cretaceous portions of the clays. The clays may be most conveniently divided into zones by refer- ence to the Belemnites, as follows :— Marly shales below the Red Chalk = zone of B. minimus and allies. Upper division of the “ Neocomian,” including the ‘“Cement- beds,” and part of the Middle Neocomian of Judd =zone of B. semicanaliculatus and allies. Lower division of the Neocomian from the top of the Pecten cinctus zone down to the base of the supposed Lower Neocomian zone of Ammonites noricus = zone of B. jaculum. From the base of the noricus-zone to the Coprolite-bed = zone of B. lateralis (zone of Amm. Astierianus of Judd). The bituminous shales below the Coprolite-bed = zone of B. Owenii and varieties. The clays of the zone of Bel. lateralis have strongly marked Jurassic affinities, and it is from this zone that the coronated Am- monites were obtained, these being the beds supposed by Leckenby to be of Portlandian age. A very well-marked band of nodules, 234 Reports and Proceedings— with some scattered coprolitic pebbles, caps the lateralis-beds, and this band constituted the ‘Coprolite-bed ” of Leckenby. The thickness of the clays above the coprolites has been over- estimated ; it is probably not more than 300 feet. The ranges which have been assigned to some of the characteristic fossils, especially Ammonites Astierianus, Amm. speetonensis, and Toxaster complanatus, need to be revised and altered. The term “ Middle Neocomian,” as applied in the Speeton section, is unnecessary and misleading, seeing that a ‘Lower Neocomian ” fauna occurs both above and below the beds with Middle Neocomian types ; and, as stated by Meyer, marly shales exist between the Red Chalk and the Neocomian clays, strongly suggestive of a passage from the one to the other, and these beds contain many Gault forms. Thus there is probably at Speeton a continuous series of clays from the Jurassic to the Upper Cretaceous, and the deposition of these beds appears to have gone on contemporaneously with the erosion of the beds inland. 2. “Notes on the Geology of Madagascar.” By the Rev. R. Baron. Communicated by the Director-General of the Geological Survey. With an Appendix on some Fossils from Madagascar, by R. Bullen Newton, Esq., F.G.S. The central highlands of Madagascar consist of gneiss and other crystalline rocks, the general strike of which is parallel with the main axis of the island, and also, roughly, with that of the crystal- line rocks of the mainland. The gneiss 1s frequently hornblendic ; its orthoclase is often pink; triclinic felspar also occurs in places; biotite is the most common mica, but muscovite is not uncommon ; magnetite is generally present, often in considerable quantities. The gneiss is often decayed to great depths, forming a red soil, and the loosened rock is deeply eaten into by streams. The harder masses of gneiss, having resisted decay, stand out in blocks, and have been mistaken for travelled boulders of glacial origin. Other more or less crystalline rocks are mica-schists, chlorite-schists, crystalline limestone, quartzite (with which graphite is often asso- ciated), and clay-slate. Bosses of intrusive granite rise through the gneiss. That east of the capital contains porphyritic crystals of felspar which near the northern edge of the granite are arranged roughly in a linear direc- tion; here also the granite contains angular fragments of gneiss. For the most part the granite of Madagascar is clearly intrusive, but this may not always be the case. The volcanic rocks are of much interest. The highest mountains, those lying to the S.W. of the capital, consist in their higher parts, of a mass of lava, for the most part basaltic, but with some sanidine- trachyte. The lava-streams are sometimes 25 miles long, and suc- cessive flows, up to 500 feet in thickness, are exposed by the valleys, From the great denudation which this area has undergone, and from the fact that no cones now remain, we may assume that this volcanic series is of some antiquity. Of the newer volcanic series there are numerous very perfect cones, dotting the surface of the gneiss in Geological Society of London. — 235 many places. No active volcano now exists in the island, but the occasional emission of carbonic-acid gas, the occurrence of numerous hot springs and deposits of siliceous sinter, and the frequency of small earthquake-shocks, seem to show that volcanic forces are only dormant and not entirely extinct. The ashes generally lie most thickly on the side of the cone between north and west; this is accounted for by the prevalence of the south-east trade-winds. The volcanic areas are ranged roughly in a linear direction, corresponding with the longer axis of the island. Sedimentary rocks occur mainly on the western and southern sides of the island. The relations of these to each other have not yet been determined; but from the fossils (referred to the European standard) it seems that the following formations are represented :— Hocene, Upper Cretaceous, Neocomian, Oxfordian, Lower Oolites, Lias. Possibly some of the slaty beds may turn out to be Silurian or Cambrian. The crystalline schists, etc., are probably, for the most part at least, Archean. Recent deposits fringe the coasts and are largely developed on the southern part of the island. Hast of the central line of watershed there is a long depression containing a wide alluvial deposit, probably an old lake-bed. Ter- races fringe its sides in many places. The lagoons of the eastern coast are due to alluvial deposits. The paper concluded with some remarks on the geological an- tiquity of the island, its separation dating from early Pliocene times, if not earlier. This is the conclusion arrived at by Wallace from its fauna; the author’s detailed researches into its flora, recently described before the Linnean Society, show that while about five- sixths of its genera of plants are also found elsewhere, chiefly in tropical countries, at least four-fifths of its species are peculiar to Madagascar. The Appendix, drawn up by Mr. R. Bullen Newton, F.G.S., con- sisted of Notes upon the fossils collected by the author, with tables, and descriptions of two new species, namely, Astarte (?) Baroni and Sphera madagascariensis, both from deposits of Lower-Oolitic age. 3. “Notes on the Petrographical Characters of some Rocks col- lected in Madagascar by the Rev. R. Baron.” By F. H. Hatch, Ph.D., F.G.S. This paper was divided into two parts, the first treating of the petrographical characters of the older crystalline rocks of the eastern and mountainous part of the island, the second of the nature of the lavas that have been erupted from volcanic vents situated mainly in the same portion of the island. i. The Older Crystalline Rocks are represented in Mr. Baron’s collection partly by foliated specimens, partly by rocks showing no parallel structure in the hand-specimen. The foliated specimens have, with few exceptions, the structure and composition of gneiss. The author subdivided them into an acid and a basic series. The acid series, which embraces rocks com- posed of abundant quartz with orthoclase as the dominant felspar, 236 Reports and Proceedings— he terms granitite-gneiss ; the basic series, which consists of rocks containing little quartz and much plagioclase felspar, tonalite-gneiss. The unfoliated specimens comprise granite, gabbro or noriie, pyroxene-granulite, and pyroxenite. The majority of the granites are of the granitite-type—t.e. they are granites with one mica; but granites with two micas are also represented. The remainder of the rocks are of a basic type. They are in- teresting, in the first place, on account of the striking combinations of fresh and beautiful minerals they present, as for example :— plagioclase, hypersthene, olivine, brown hornblende and green spinel, in an olivine-norite; or, plagioclase, green pyroxene (omphacite or diallage), hypersthene, hornblende, garnet and iron-ore, in pyroxene- granulite; or, again, diallage and hypersthene in pyromentte. But of greater interest is the fact that these basic types, which are so well known in other territories of old crystalline rocks— Saxony, Brittany, Scandinavia, Scotland, the Hudson River, etc.— constitute in Madagascar, as they do at Kilima-njaro on the adjacent mainland, a large part of the ancient platform on the submerged portions of which the sedimentary rocks have accumulated, and through which the volcanic lavas were erupted. il. The Volcanic Rocks.—In composition these are acid, inter- mediate and basic, mainly the latter. The acid and intermediate types are described are sanidine-trachyte and hornblende-augite-andesite. The basic rocks consist of various types of basalt. They vary with respect to the presence or absence of corroded quartz-grains, olivine, porphyritic hornblende, and biotite. In one interesting type the hornblende appears in small idiomorphic crystals as a constituent of the ground-mass. A felspar-free variety, or magma-basalt, is also represented. This rock contains only a small quantity of olivine, and is therefore intermediate between Rosenbusch’s Limburgite and Dolter’s augitite. IIJ.—March 20, 1889.—W. T. Blanford, LL.D., F.R.S., President, in the Chair.—The following communications were read : 1. “Supplementary Note to a Paper on the Rocks of the Atlantic Coast of Canada.” By Sir J. W. Dawson, K.C.M.G., F.B.S., ¥.G.8. In a paper in the “Journal” for November, 1888, the author referred to the Olenellus-fauna as characterizing the Middle Cam- brian. The fauna, he has no doubt, from the recently published observations of Walcott and Matthew, should be regarded as charac- teristic of the Upper Member of the Lower Cambrian. From this arises a new view of the physical geography of the period, namely, that the Lower Cambrian was, in America, a period of continental depression, and the Middle Cambrian a period of continental elevation, leading to the important conclusion that a time of elevation inter- vened between the Huronian and the early Cambrian, which may represent the apparent gap between these systems in LHastern America. He thinks that this new view deserves a special mention Geological Society of London. 237 in connection with the probability that the Huronian and Kewenian beds are of littoral origin. 2. “The Occurrence of Colloid Silica in the Lower Chalk of Berkshire and Wiltshire.” By W. Hill, Esq., F.G.S., and A. J. Jukes-Browne, Hsq., F.G.S. In the Lower Chalk of Berks and Wilts are beds which contain a large amount of disseminated colloid silica; these are comparable in general structure to the Malmstones of the Upper Greensand. Dr. Hinde’s study of the latter led him to believe that the globular colloid silica which they contain was directiy derived from the remains of siliceous sponges, and the authors’ studies of the Chalk specimens have confirmed this conclusion by adding several im- portant pieces of evidence. They found that the amount of free disseminated silica increases in proportion to the number of spicules and calcite-casts of spicules which occur in the rock, and observed that the great similarity be- tween the siliceous chalk and the Malmstone was heightened by the occurrence of similar siliceous concretions in both rocks, the material of which might be described as siliceous chalk, indurated by a cement of chalcedonic silica. ‘The conditions in which the silica was found in the Lower Chalk were described, in examples varying from those containing least to those which held most silica; in the latter the amount of colloid silica was estimated at 12°61 per cent. by weight. After noticing the vast amount of silica present in rocks with a maximum thickness of 70-80 feet, the authors discussed the diffi- culty of accounting for this, and drew attention to Prof. Sollas’s statement that many living siliceous sponges constantly shed some of their spicules. A further question arose as to whether the formation and accu- mulation of globular silica went on contemporaneously with the deposition of the calcareous material upon the sea-floor, or whether the conversion of the spicules into such silica took place after the consolidation of the rock, and the authors gave reasons for sup- posing that the latter was the case, the change having occurred when the rock was in a sufficiently oozy condition to admit of easy molecular distribution. Reasons were given for supposing that the disseminated colloid silica had not been derived directly from the disintegration of spicules in which a globular structure had been previously developed, but that the globular silica was precipitated from solution whilst the beds were still permeated by sea-water. The precipitation of the chalcedonic silica was regarded by the authors as a secondary and subsequent operation. ‘They were dis- posed to regard all nodular concretions resembling flints and phos- phatic nodules as growths, which were more or less contemporaneous with the deposition of the materials of the enclosing rock, and in conclusion they offered some comments upon the problem of the formation of flints. 3. “Note on the Pelvis of Ornithopsis.” By Prof. H. G. Seeley, F.R.S., F.G.S. The remains preserved in Mr. Leeds’s collection at Hyebury, and 238 Reports and Proceedings— described by Mr. Hulke, are the largest and most perfect pelvic bones of a Saurischian known in this country. An examination showed that the bones of the right and left sides were united in the median line almost throughout their length by a median suture, and that they formed a saddle-shaped surface internally from front to back. After giving a detailed description of the pubis and ischium, the author stated that he was not aware that this type of pelvis had been previously observed. He noted that the antero-posterior concavity between the anterior symphysis of the pubic bones and the posterior symphysis of the ischia was a well-marked charac- teristic of Saurischian reptiles, but that it remained to be determined to what extent the median union of the pubic bones was developed in the group. It was impossible to judge of the form of the ilium from the imperfect fragment preserved, but it did not make any recognizable approximation to the bone in those American genera which offered the closest resemblance of form to the pubis and ischium. There were several minor differences of proportion between the bones from the Oxford Clay and those from the Wealden of the Isle of Wight, and the former differed in ways pointed out from Morosaurus, Diplodocus, and Brontosaurus, though there were re- semblances. I1I.—April 3, 1889.—W. T. Blanford, LL.D., F.R.S., President, in the Chair. The President announced that according to a circular lately re- ceived from the “Sociéte Géologique de France,” that Society pro- posed to hold its Extraordinary Meeting this year in Paris, the date being fixed for the 18th August next. Meetings will be held in Paris, the collections in that city will be visited, and there will be a series of excursions to places of interest within easy reach of Paris, on successive days of the week devoted to the Meeting. These are specified on the circular; and in the week following the Meeting, excursions will be-made to more distant localities, of which the Auvergne and Brittany are particularly mentioned, that to the former district under the guidance of M. Michel-Lévy, and that to Brittany conducted by M. C. Barrois. Arrangements will be made with the railway authorities for a reduction of 50 per cent. upon the fares; but in order to secure this advantage the names of persons intending to attend must be sent to the Secretaries of the Society before the Ist July, 1889. British Geologists, and especially Fellows of the Society, are cordially invited to be present. The following communications were read :— 1. «The Elvans and Volcanic Rocks of Dartmoor.” By R. N. Worth, Esq., F.G.8. The object of this paper was to give reasons for the belief that the present granite of Dartmoor passed upward into felsitic and volcanic rocks, remnants of which are to be found in the Triassic conglome- rate of Devon, in the detritus of the bottom lands of the moor itself. on the beaches of the channel, and in ancient river-gravels and pebble-beds ; to indicate the wide range of character taken by the Geological Society of London. 239 felsites of the Dartmoor district; and to point out some of the evidence which exists in the in-siéw elvans for the development of the most varied of these forms from a common magma. Special opportunities for the study of two of the elvanite dykes in the neighbourhood of Tavistock have lately presented themselves. The Shillamill elvan exhibits a centre composed of quartzose felspar- porphyry graduating laterally through numerous varieties into “claystone porphyry’; whilst the Grenofen elvan retains the same structure in breadth, but changes in length from a rock containing so little felsitic matter that it is essentially a fine-grained porphyritic granite, to one with a compact semivitreous ground-mass, in which felspars, quartz, mica are porphyritically developed. As evidence afforded of the existence of distinctly volcanic rocks, mention is made of a deposit of water-borne and water-worn detritus, indicating a Dartmoor origin for a large portion of its constituents, along with rolled flints and pebbles of Carboniferous, Liassic, and Cretaceous limestone, with which were associated typical andesites and specimens of voleanic grit such as arise from denudation of voleanic cones. This occurs on the limestone at Cattedown near Plymouth, and bears testimony to a very ancient denudation. 2. The “Basals of Hugeniacrinide.” By F. A. Bather, Hsq., B.A., F.G.S. Although Professors Beyrich and v. Zittel had alluded to certain specimens of Hugeniacrinus as proving, by the course of the axial canals, that in this genus the basals had passed up into the radials, yet the two chief authorities who subsequently discussed the subject practically ignored this argument. M. de Loriol contented himself with denying any trace of basals, while Dr. P. H. Carpenter main- tained that the top stem-joint represented a fused basal ring. In a previous paper the author had argued in favour of Prof. v. Zittel’s view without convincing Dr. Carpenter of its correctness. Such scepticism was, no doubt, warranted by the lack of detailed descrip- tion and of figures. ‘The object of the present note was to set the matter at rest by describing and figuring certain dorsal cups of Hug. caryophyllatus kindly lent to the author by Prof. von Zittel. Owing to the mode of fossilization the canal system is plainly seen. ‘The axial canal passes up into the radial circlet and gradually widens; at a short distance below the floor of the calycal cavity it gives off five interradial branches; these soon bifurcate, and the adjacent radial branches converge. Before they meet, each radial branch gives off a very short branch; this connects the radial branch with the ring-canal that contained the interradial and intra-- radial commissures. The evidence of all other Crinoids that have these canals shows that the basals always contain the interradial branches. And in Bugeniacrinus, since the interradial branches have their origin in the middle of the radials, the basals must have passed up in between the radials, 8. “On some Polyzoa from the Inferior Oolite of Shipton Gorge, Dorset.” By H. A. Walford, Esq , F.G.S. 240 Reports— Geological Sorreny of London. The author referred to the little attention the Jurassic Polyzoa have received in England, a few scattered papers comprising the whole of the literature of the subject. This may be accounted for, in part, by the rare occurrence of conditions favourable to the pre- servation of the delicate features necessary for their true study, and in part, also, by the difficulties into which the classification has drifted. The series dealt with has been collected from the Inferior Oolite, zone of Ammonites Parkinsoni, at Shipton Gorge, Dorset, and the number of forms from the single horizon and locality was stated to be equal to the whole of those described by Jules Haime from the Lias to the Kimeridge Clay. Associated with the Polyzoa are Crania Moorei, and sp., Thecidea, sp., Rhynchonella senticosa, Tere- bratula Phillipsii, Ammonites Martinsii, some Hchinoderms, and a large series of sponges. ‘The tranquil conditions prevailing during the deposition of the beds are indicated by the presence of many slender and arborescent forms of Polyzoa, and the little abrasion they have suffered, as well as by the presence of numerous sponges. The author, in briefly reviewing the Cyclostomata, adopts the simple divisions of Mr. Waters, the Parallelata and Rectangulata, based upon the Hincksian system. The disregard of zoarial growth, in any great degree, as a means of classification, would lead to con- fusion under the present modes of grouping; neither, however, can any great constancy be found in the form of the zocecia or in the shape of the aperture. In the group Stomatopora six species are recognized, of which two are new. Amongst the Proboscing is a species described in that stage of growth as Proboscina spatiosa, which passes into both Tubuliporoid and Diastoporoid forms, and also in the latter phase throws off erect Entalophoroid branches. The author has used the same specific name for each form, though describing them under different generic names. Considerable variation in size and shape of cell occurs in each stage. The Idmonee are represented by two new species and two new varieties; Lisidmonea by one form only. Though the latter has much the appearance of Hntalophora, the character of the ovicell is so definitely that of the associated Idmonea as to decide its relationship, and it has also the cell-type of Idmonea. In the group Entalophora d’Orbigny'’s Cretaceous species Hnéalo- phora raripora and £. subgracilis are quoted, the latter, however, under a varietal form. EH. anomala, Manz., EL. richmondiensis, Vine, and one new species, H. magnipora, complete the list so far. MISCHIDANHOUS. Western Avstratia.—From Reports received, it appears that the Gold-fields of this Colony are likely to prove as rich as those of Eastern Australia. But we are still more glad to learn that the Coal-seams on the Irwin River, noticed by Gregory in 1863, are now being successfully worked, and promise excellent results. Western Australia has already 450 miles of railroad, and if coal can be obtained close to the northern terminus at Geraldton, it will be of the highest value. nMoweby STLETNSUe sny{OUCTASTT “Yat a9 [ep Keprsepy 9 ne 2 laa ‘dur ,o7 UeuIman 8e\\ O ® D) ro TIA TA IATA TH Pe eO°d ‘e@QQT Sep Joe) THE GEOLOGICAL MAGAZINE. NEW. SERIES:, .DBGADE Ill.,.VOL.. VI. No. VI.—JUNE, 1889. @ie a GIN PAS ae ee ao Cae So J.—Ow a New Specimen or Hisrionorus anGuLaris, Egerton. By J. C. Mansuu-Preypewn, F.L.S., F.G.S. (PLATE VIL.) ESTION OTUS ANGULARIS, was first described and figured by the late Sir Philip de M. Grey Egerton, Bart. F.R.S., in Decade viii. of the Memoirs of the Geological Survey, 1853. The uninterrupted dorsal fin, extending from near the occiput to the tail, suggested the generic name of HWistionotus,' and in this feature it re- resembles Ophiopsis. It has the characters also of other genera, for instance, Pholidophorus in its scales, Semionotus in the shape of its body, and Lepidotus in the shape of its head. Sir Philip Egerton, misled by the imperfect preservation of the posterior end of his specimen, thought the caudal-fin to be also similar to that of Lepidotus. By a singular coincidence, a fine specimen of Lepidotus minor lies side by side on the same slab with the subject of this note (PI. VII.), and the caudal fin of each is well exposed, showing that of Zepidotus to be comparatively short and truncate, while that of Histionotus is deeply forked. In its crushed condition, the upper lobe in Histionotus is longer and larger than the lower lobe; but this is proved to be a deceptive appearance by another example of the genus I have since met with from the same quarry which displays the symmetry of the tail-fin, the lobes being beautifully shown of equal length. The outline of the upper portion of the body is triangular, rising abruptly from the snout to a distance of 20 millim. beyond the base of the occiput along the dorsal ridge, and then descending by a less abrupt gradient from this culminating point to the base of the caudal fin, a distance of 85 millim. The depth of the body at the most elevated part of the dorsal ridge to the pectoral fin is 65 mm., to the shoulder-girdle 83 mm. The anterior margin of the first ray of the dorsal fin, which is stouter than the others, is furnished with a series of fulcral rays. The remaining rays, of which there are more than twenty, bifurcate about half-way from the base, and the distal halves are again bifurcated and cleft. The pectoral fin consists of seven rays, of which the first is the longest and stoutest, and all are bifurcate 1 forios, a sail, yaros, a back. DECADE III.—vVOL. VI.—NO. VI. 16 242 = JS. C. Mansel-Pleydeli—On Histionotus, a Purbeck fish. and split. Each ventral fin, which is 20 mm. long, has only four rays, the first exceedingly stout and furnished with a series of large marginal fulcra; and all the rays are transversely articulated or jointed beyond the point of bifurcation. The anal fin has four rays also, and is the smallest of all; the length of the largest ray being 15 mm. The caudal fin consists of eight rays in each lobe, the upper lobe appearing 40 mm. long, whereas the lower is only 25mm. The margins of the upper ray of the larger lobe and of the lower ray of the smaller are furnished with a series of large fulcra which probably increased the locomotive power of the tail. The depth of the shoulder-girdle is 25 mm., and the breadth of the post-clavicular plates (p. cl.) 5mm. The opercular apparatus is well preserved, showing distinctly the operculum (op.), sub- operculum (s. op.), interoperculum (7. op.), and preoperculum (p. op.), besides a few branchiostegal rays (br.). These, like the post-clavicular plates of the shoulder-girdle, are all enamelled. The bones of the head are much crushed. The maxille, although perfect, are displaced; and a portion of the right premaxilla is preserved, showing seven teeth, with part of the eighth. These teeth are styliform, slender, straight, and smooth, and appear to decrease in size from front to back. The largest is 2 mm. in length. The vomerine bones are hidden, which unfortunately prevents our ascertaining whether or not the roof of the mouth is armed with teeth. The orbit is obliterated by the intrusion of the underlying skull-bones. The scales of the body are small as compared with those of Tepidotus, and are not so lustrous. Those of the flank measure 6 mm. in depth and 2 mm. in breadth. They are rhomboidal in shape, finely pectinated on the posterior exposed margin, arranged obliquely in rows from the dorsal to the ventral region, twelve in a series. The lateral line from head to tail extends along the middle of the flank. Between the last ray of the dorsal fin and the base of the caudal, are three double-cone-shaped lustrous ridge-scales, which may have served to strengthen this attenuated part of the body, enabling it to resist the strain upon it when the caudal fin was in action. Length of body beh, (ame 1:80 m. fs tail, upper lobe Poi Leoni see aceerey mane s: USO) Wi, Be sie) MG WEEIODSWN ce). ssiu ee meme wescr pcset Tce aeNO man A head 500). Hae 0:46 m. Breadth of head 0:40 m. EXPLANATION OF PLATE VII. Histionotus angularis, Egerton; right lateral aspect of fish, nat. size- Middle Purbeck Beds, Swanage, Dorsetshire. dr. branchiostegal rays. 7%. op. interoper- culum. op. operculum. yp. cl. post-clavicular plates. yp. op. preoperculum, s. op. suboperculum. : The specimen from which the above description is taken, and which is figured in the accompanying plate, was procured by me from a quarry at Herston, near Swanage, Middle Purbeck. It is now preserved in the Dorset County Museum, Dorchester. WHATCOMBE, BLANDFORD, DoRSETSHIRE. Prof. J. W. Judd—Statical & Dynamical Metamorphism. 248 IL.—On Srarican anp DynamicaL MrramMorPHisM. By Prof. Joun W. Jupp, F.R.S. T has long been recognized by geologists that rock-masses which have undergone movement, and have thereby been subjected to internal stresses, exhibit, as the consequence of the action upon them of such mechanical forces, unmistakeable evidences of having been greatly modified, alike in their mineralogical and in their structural characters. That the most complete and striking examples of such changes are to be found in the rock-masses which constitute mountain-chains—rock-masses which have actually been made to “flow,” and in so doing have been subjected to shearing movements of the most intense character—was clearly pointed out by Scrope, Darwin, Sharpe, Naumann, and Dana; all of whom referred the foliated structure exhibited by such rock-masses to this cause. The careful study, in recent years, of the actual processes involved in bringing about such changes, has rendered necessary the adoption of certain terms, to define the nature of the action in particular cases. In 1869, Lossen proposed to call the changes produced during rock-movements “ dislocation-metamorphism ”’ (dislocationsmetamorphismus) ;' while four year later Baltzer invented the term ‘‘ mechanical metamorphism” (mechanischer metamorphismus) ;* in 1884 Gosselet suggested the term “ friction- metamorphism” (métamorphisme par friction);* and in the following year Giimbel employed the name ‘“ compression-meta- morphism” (stauungsmetamorphose) ;* while in 1886 Bonney pro- posed to use the term ‘“ pressure-metamorphism.” ° Rosenbusch, in the same year, seeking to bring clearly into view the consideration that the special kind of metamorphism referred to is only produced when the mechanical forces effect movement, and thus do work, suggested the term Dynamical meta- morphism or dynamometamorphism ;° and this term, if not absolutely free from objections, is so convenient that it bids fair to be generally adopted. There is perhaps at the present time a tendency to exaggerate the results of this particular agency of dynamical metamorphism, and to overlook or minimize the importance of other contributory causes to the alteration of rock-masses. I desire in this note to call especial attention to the remarkable effects which result from the chemical and crystallizing processes which certainly go on at great depths, and under enormous pressures, even when the rock-masses do not yield to the pressures and thus become subjected to the movements which 1 Zeitschr. d. d. geol. Gesellsch. Bd. xxi. pp. 282-340. 2 Der Glarnisch (1873), p. 58. ‘3 Ann, Soc. Géol. du Nord, xi. (1884), p. 188. 4 Geol. von Bayern, i. p. 379. ® Ann. Address Geol. Soc. Q J.G.S. vol. xlii. (1886), p. 62. 5 Der Massige Gesteime, 2nd ed. 1886. 244 Prof. J. W. Judd—Statical & Dynamical Metamorphism. result in dynamometamorphiec action. Such changes, resulting from pressures that do not effect movements in the rock-masses, may be — appropriately called “ statical metamorphism.” The researches of modern physicists are beginning to enable us to realize what are the chief factors in these processes which go on at great depths within the earth’s crust. The striking experiments of Guthrie have shown that there is a perfect gradation between the states of fusion and solution, and have enabled us to realise the im- portant part played by even small quantities of water or other liquids held under great pressure in the deeper and highly heated masses of the earth’s interior.’ The researches of Spring, van’t Hoff, Reicher, and others have shown the effects of pressure in bringing the mole- cules of solid bodies sufficiently close to one another for chemical affinity to operate between them; and especially significant to the geologist is a recent conclusion arrived at by the first-mentioned physicist, that when the particles of a solid are brought into juxta- position by the action of mechanical force, the chemical processes may go on even after the pressure is removed. ‘Time, it is thus shown, may become an important factor in such changes.” And, lastly, Van der Waals in his remarkable essay on “The Continuity of the Gaseous and Fluid States” has shown that “all bodies can mix with one another when the pressure exceeds a certain value.” * That at great depths and under the enormous pressures within the earth’s crust, the whole substance of solid rocks—crystallized minerals and glassy groundmass alike—may be traversed by various liquids and gases, I think it is impossible to doubt. In various papers in which I have endeavoured to establish and illustrate the theory of ‘«Schillerization,” * I have shown that rocks, which at any point of their history have been deep-seated, have undergone very remarkable changes—their minerals having been metamorphosed and trans- formed, and their original structure sometimes completely altered ; these changes, which have taken place quite independently of any movement that the rock-masses may have been subjected to, can there- fore be spoken of as statical metamorphism. A striking illustration of the truth of the conclusions arrived at by Van der Waals is afforded by the fact, that in the interior of rock-forming crystals, we find cavities (indisputably formed by solvent action long subsequently to the formation of the minerals themselves), containing at the same time, various supersaturated aqueous solutions and also carbon-dioxide retained in the liquid condition by pressure. It may be of interest at the present time to draw a comparison 1 The bearings of Dr. Guthrie’s researches on geological problems have been already pointed out. See this Macazinz, Dec. III. Vol. V. p. 1, 1888. 2 Amer. Journ. Sc. 3rd ser. vol. xxxvi. (1888), p. 288. 3 I am indebted to my colleague Prof. Riicker, F.R.S., for calling my attention to the valuable researches of Van der Waals,which have had such an important influence on the views of physicists. His essay, which was translated from the original Dutch into German in 1881, is now about to be issued in English form by the Physical Society. ° Gare Journ. Geol. Soe, vol. xli. (1885), pp. 374-389 ; Mineralogical Magazine, vol. vii. (1886), p. 81. Prof. J. W. Judd—Statical & Dynamical Metamorphism. 245 between the effects of Eee and dynamical metamorphism respectively. Setting aside the more purely mechanical effects which may precede or accompany dynamical metamorphism—such as cleavage, jointing, the crushing or deformation of included fragments, the stretching of rocks, and the production of “mylonitic” bands—the results of this agency may be classified as follows :— First.—The inducement of metamorphoses in the constituent minerals of a rock. That minerals are capable, without losing their identity, of undergoing remarkable metamorphoses, whereby their chemical, crystallographical, optical and other physical properties may be modified within certain—though often indeed very wide—limits, is now beginning to be recognized by both mineralogists and geologists. The production of twin-lamellation in many minerals by internal and external stresses, and the defor- mation of crystals by these means, so that they assume not only the external angles, but the internal structure and the optical properties of complex twins belonging to a system of lower symmetry than their own, are now well-recognized facts. An admirable illustration of this action is afforded by the production of microcline from orthoclase. The beautiful experiments of Des Cloizeaux, Dufet and Bucking on this same mineral species, orthoclase, have shown that both by heating and by pressure the position of the optic-axial plane, and the angle between the axes may undergo temporary changes; while, if the temperature or pressure pass beyond a certain limit, these changes become permanent. The study of the minerals of the enstatite-group has shown that as certain chemical changes go on within their crystals, these, while retaining their orthorhombic symmetry, may undergo the most remarkable modifications, not only in their colour, pleochroism, and absorption, but also in their index of refraction, in the sign and intensity of their double refraction, in the position of their optic-axial plane and in the angle between their axes; and further, that, changes in specific gravity, in hardness and in fusibility may accompany these several modifications. That the form and position of the ellipsoid of elasticity in a crystal may be altered temporarily and even permanently by the action of heat, pressure, or chemical agencies, is a phenomenon for which we ought to be fully prepared; and it is upon the form and position of this ellipsoid that the so-called optical “constants” of a mineral depend. That the metamorphoses which have been more or less fully investigated in the case of a few species, like orthoclase, enstatite, pelenite, etc., are not confined to those species must be alent to all who have been in the habit of studying the so-called “ optical anomalies” of minerals; and such “anomalies” are especially fre- quent in the case of the common rock-forming species. When we remember the nature of the forces to which the constituent minerals of rocks must have necessarily been subjected in many cases, we shall cease to wonder at this result. Secondly. As there must be, in every case, a limit beyond which a 246 Prof. J. W. Judd—Statical & Dynamical Metamorphism. mineral cannot change without losing its identity, the final result of the internal stresses set up in a rock-mass is that the constituent minerals are gradually transformed into totally different ones. This transformation may take place in two different ways sa) isi), paramorphic, or change into a new mineral species crystallizing in the same or a different system, but having the same chemical composition; or secondly, metachemic (to use Dana’s convenient term)’ when, in consequence of the addition or subtraction of materials, or of both of those processes combined, the chemical composition as well as the crystallographical characters of the substance undergoes complete alteration. Thirdly.—This change in the mineralogical constitution of a rock may be accompanied by a modification, more or less complete, in its structure. The structures which usually result from the action of dynamical metamorphism are the granulitic, and the foliated or schistose. It must be remembered that while these changes in struc- ture may undoubtedly take place in rock-masses which have long since acquired the solid condition, they are also liable to arise in masses which are still in a plastic or viscous condition, and as the result of a primary rather than of a secondary crystallization when the mass is under the influence of internal stresses and movements. I have shown how completely the granulitic structure may be developed on the sides of great intrusive masses of gabbro; and General McMahon has well illustrated the production of foliation in intrusive granite-veins. Hven in hypocrystalline rocks, like the more acid lavas, as Scrope and Darwin so admirably proved, the shearing movements in a slowly moving, viscous mass give rise to phenomena having the most striking resemblance to the foliation of the crystalline schists. Let us now direct our attention to the class of changes which take place in rocks which are subjected to great pressure, but in which this pressure has not produced differential movement resulting in shearing. In these cases the most potent agency by which change is effected consists in the penetration of the whole mass of the rock by various liquid or gaseous solvents. It is for the whole group of such changes—of which “schillerization” is a conspicuous example —that I propose to employ the term statical metamorphism. Such statical metamorphism can often be shown to have taken place in the same rock-masses which have undergone dynamical metamorphism —the statical metamorphism either preceding or following the dynamical metamorphism. The effects of statical metamorphism may be conveniently classed under the same three headings which we have employed in consider- ing the results which are produced by dynamical metamorphism. First.—The metamorphoses of the constituent minerals in a rock. We cannot perhaps better illustrate the nature and variety of the changes which take place in minerals subjected to great pressures 1 Amer. Journ, Sci. (1886), vol. xxxii. p. 69-71. Prof. J. W. Judd—Statical & Dynamical Metamorphism. 247 than by referring again to the very widely distributed species ortho- clase. This mineral, according as it has been formed near the surface or at great depths, assumes the special crystallographic habit, the lustre, density and other properties which characterize sanidine and adularia respectively. But, subsequently to their formation, the crystals may have their optical characters completely altered either by heat or pressure, so that the position of the optic-axial plane and the angle between the axes change to those of anomalous orthoclase (orthose deformé). On the other hand, the great mechanical stresses, to which rock-forming orthoclases have in some cases been sub- jected, has frequently caused them to assume the external angles, the internal structure and the optical properties characteristic of microcline. But there are a number of other changes that orthoclase-crystals are subject to, which, though they have certainly been produced only in crystals that have existed in deep-seated rock-masses, yet cannot be referred to any process of dynamic metamorphism. Almost universally, the crystals of orthoclase in such deep-seated rock-masses are found to have lost their transparency and vitreous lustre, and to have acquired the opacity and pearly lustre, often with the red, pink, grey or green tints distinctive of common orthoelase. Sometimes the separation by chemical agencies of minute particles in the transparent mass has gone on in such a manner as to give rise to the scattering of light which results in “opalescence.” We have thus produced the opalescent orthoclase, some forms of which are known as “ moonstone.” If the change results in the formation and infilling by foreign deposits of negative crystals lying in their solution planes, then the result is an avanturine or schiller orthoclase, to which some of the so-called ‘“ sunstones ” must be referred. If the structures developed in the crystals by these agencies be of ultramicroscopical dimensions, we may have the beautiful interference phenomena produced, which are characteristic of iridescent orthoclase. The important researches of Stokes and Madan, and especially those recently undertaken by Lord Rayleigh, upon the artificially formed iridescent crystals of chlorate of potash, promise to throw much new light upon the obscure question of the theory of such a play of colours as exhibited by certain minerals. The chemical changes which take place along certain definite planes within a crystal of orthoclase may result, not only in developing a particular lustre along these planes, but also in giving rise to a tendency to division along them (pseudo-cleavage), and we thus get the beautiful variety known as Murchisonite. Lastly, the crystal after having undergone any or all of the changes above indicated, may, in consequence probably of changes of temperature, break up more or less regularly along certain planes (‘‘contraction-rifts”’) ; and, in the clefts thus produced, secondary deposits of albite or some other form of felspar may be deposited giving rise to the varieties known as Perthite and Microperthite. Similar series of changes may be traced in the case of many— 248 Prof. J. W. Judd—Statical & Dynamical Metamorphism. perhaps of all—the rock-forming minerals, which have been subjected to deep-seated chemical action within the earth’s crust. Secondly.—The mineral (often greatly altered in its chemical constitution by one or other of the processes above described) may undergo complete transformation—either paramorphic or meta- chemic. Thus orthoclase, according to the nature of the solvents and the conditions under which they operate, may be converted wholly or in part into a zeolite, into muscovite or some hydrous mica, into epidote, into a kaolinite, or into some other type of mineral. It may be interesting to illustrate in a tabular form the chief metamorphoses to which the species orthoclase appears to be subject, and the complete transformations of which it is ultimately susceptible : A. Forms dependent upon the conditions wnder which the crystals were originally produced. 3 Adularia. Sanidine. B. Forms resulting from physical or chemical changes, induced by statical or dynamical metamorphism. Anomalous Orthoclase Common Orthoclase. (Othose deformé). Opalescent Orthoclase. Microcline, Avanturine Orthoclase. Iridescent Orthoclase. Murchisonite. Perthite. C. New minerals resulting from the further alteration of Orthoclase. Zeolites. Micas. Epidotes, etc. Kaolinites, etc. Thirdly.—Statical metamorphism, by giving rise to the development of new minerals in a rock or to the growth of old ones, may lead to a complete change in the structure of a rock. Holocrystalline rocks are those in which the whole of the materials have acquired the crystal- line character without interruption, the time before their complete solidification having been sufficient for the prevention of any im- perfectly crystallized residue being left. Such rocks may be regarded as being in the most stable condition. But with the hypocrystalline rocks the case is otherwise. We have a stable portion produced by the uninterrupted action, up to a certain point, of crystallization, and an unstable portion produced during the more sudden solidifi- cation of the residue. In such a rock, when subjected to the process of statical metamorphism, the stable crystals may grow at the expense of their unstable surroundings, and, as I have recently shown, many new and remarkable rock-structures may result from this process.! It is very difficult to define any limits to the processes of statical metamorphism. The effects of such operations can be best studied in the case of igneous rocks—especially those belonging to a late period in the earth’s history—that have been situated near volcanic centres and afterwards exposed to our study through denudation. In such cases the phenomena which have to be investigated are less liable 1 Quart. Journ. Geol. Soc. vol. xlv. pp. 175-186 (1889). Prof. J. W. Judd—Statical & Dynamical Metamorphism. 249 to be complicated and obscured by the results of other processes of change, than in older rock-masses of similar origin. Around volcanic centres, too, the rate of the rise of the temperature with descent is probably more rapid, and the solvent agents are more abundant than elsewhere; and it is also more easy to trace the effects of these agents upon the definite minerals making up the plutonic rocks, than in other cases. But all rocks at great depths must be subjected to high temperatures, to enormous pressures, and to some solvent agents ; and it may well be that at such depths a condition approaching to fusion or to solution may be reached, which permits of perfect re- crystallization of the rock materials; such a state of things would seem to be advocated by Dr. A. C. Lawson and Dr. G. Dawson, as having probably occurred in the case of the rocks which cover so _ large an area in Canada. I cannot perhaps better illustrate the complicated results of the joint action of statical and dynamical metamorphism than by ~ referring, as briefly as possible, to the cycle of changes which can be shown to have occurred in the case of a particular rock. The so-called Apatit-bringer of Oedegarden, near Bamle, in Norway, is a rock consisting essentially of hornblende and scapolite, which, as shown by the beautiful experiments of Fouqué and Michel Lévy, can, by fusion and slow cooling, be converted into an aggregate — pyroxene and felspar. That the rock was originally a pyroxene- felspar-rock which has been metamorphosed into a hornblende- scapolite one, the observations of Sjogren and others sufficiently indicate, and we are now able to show the exact series of processes by which the transformation has been effected.t In certain specimens the pyroxene (an enstatite) may be seen ‘to have acquired, through a process of statical metamorphism, the peculiar characters of bronzite; and, by the same means, layers of cavities are developed along the twin-planes of the felspars, which cavities are filled with supersaturated solutions of sodic chloride. Statical metamorphism having carried the change thus far, dynamt- cal metamorphism has next come into play, and the bronzite has been converted into hornblende and the mixture of felspar and sodic chloride into scapolite; the former by a paramorphic, the latter by a metachemic transformation. At the same time the structure of the rock has been changed from a granitic to a granulitic one. This particular case is one of more than ordinary interest from our being able to study all the stages in the complete cycle of change, from a pyroxene-felspar rock to a hornblende-scapolite one, and back again to the former. But there are many other instances in which careful study may enable us to follow many of the succes- sive steps by which very similar changes have been gradually effected. 1 Mineralogical Magazine, vol. vili. p. 186. 250 Capt. Marshall Hall—Swiss Geological Excursion. IIJ.—A Weex’s Grotocicatn Excurston to tHe Swiss ALPS. By Capt. Marsnart Hatt, F.G.S8., F.C.S., ete. Wee following notes were drawn up by the writer some years since as a sketch for an excursion by members of the Geologists’ Association to the Alps, and it may perhaps still prove acceptable to geologists who this year intend to visit Switzerland for the first time. Leaving London any morning and proceeding onwards by the night-train from Paris, we may breakfast at Lausanne railway- station on the following morning. Take steamer from Lausanne (Ouchy) for Villeneuve, where we have a good example of an anticlinal valley—that of la Tiniére. Thence by rail to Vernayaz, where sleep. I need hardly summarize the geology round Lake Leman; in the train from Villeneuve remark the wave-crest form characteristic of the Jura seen from north, and the rock-fall at Roche ; on the right the great one near Vouvry. The Triassic rocks are all interesting ; and on the left after leaving Aigle are the fine marble quarries of St. Triphon. As you approach Bex you will observe the monticule called le Montet, which is principally a mass of gypsum. Bex with its salt mines would be well worth half a day’s exploration. Between that and St. Maurice we are in the Cretaceous formation. At the Baths of Lavey (left hand) we enter the Carboniferous region, consisting here of metamorphic schists. Remark any number of “roches moutonnées” and glacier-worn rocks. Of the picturesque nature of our route I say nothing—is it not recorded in many excellent guide-books ? Next morning visit the Gorges du Trient, and thence the Pissevache, whence a rough zigzag leads over schists and by slate quarries to a point half-way up the carriage road to Salvan. This road winds up an interesting gorge, with a repetition on each side of slates at the bottom, Carboniferous grits, anthracitic and mica-schists and metamorphic schists, and grits. The heights above are gneiss. Salvan is an hour and a quarter’s fair walk from Vernayaz, up a good char road, but with a pitiless series of, I think, fifty-two zigzags, and, once fairly out of them, a gentle hill. Some ten minutes before reaching Salvan and five minutes off the road to the south-east are some very remarkable “ marmites des Géants,” i.e. the ancient pot-holes of glacial times, worn by water falling through “moulins.” 'They show the pestle and mortar action, their centres rising in the form of cones. On the opposite side of the valley of the Rhone the Dents de Morcles rising more than 10,000 feet have been growing more and more grand, and the replications of the strata, of which a sketch after that by Professor E. Renevier is given (see Pl. VIII. p. 251, opposite), are very specially remarkable, and, even at that distance, quite evident. The geological map of the “Alpes Vaudoises,” by the same geologist, marks “ Poudingues de Valorsine” at Salvan. One charming walk, scarcely known to the Cockney tourist, is a GEOL. MAG. 1889. DECADE III. VOL. VI. IPL, VIII. Ei E 3 N.W. Ag R a S.E. OD ae g E TX 7 Y D . 8 a ee a a s oe se ne me B 4 ieee 8 SES Sy} Sy Se a . A H G8 ad H 2) 0 é g KN ae | Z g =) Ke) 2aSS UD IULOICA No > i a = ea s a R ge a e a4 He O Gy Z } E: Md 3 a + Boe NI a a. LD ice oe SS fod 5 NY ss rae 7 7 ka 2 9 <= SY we f a [ONE ns . 3} i ~ ry é ae | N, i al ) % ? SS 0 3S a ZA Se ee noo ee Sra pas ee a 55) 5 Bay oe << ; ie ( é : pa oa Guise of te Lioite, 3 8 4 a 8 5 Kore. v 3 ay a pe hore 8 g § : a oH EI iq 2 5 i o 2 8 a 4 5. u = SG 3 Sea devel. Ca) Ke = A Pa Pa EN seadeued 4 = Se Au Sea Ceved. Geological Section of the Dents de Morcles, by Prof. E. Renevier. (Scale 1°50,000 for distances and altitudes.) [Two sections combined and re-drawn from the originals by G. C. Crick, F.G.S.] 252 Capt. Marshall Hali—Swiss Geological Excursion. couple of hours up to La Creuse, whence is a splendid view of Mont Blane. And I think the approach to the valley of Chamounix by this side of the valley far more interesting than that by the Téte Noire. The upper portions are gneiss. M. Renevier maps them as ‘“schistes et grés metamorphiques,” differing in this from the late Professor Studer, as the latter mentioned to me in several conversations. The traveller should return to Vernayaz, or go on to Martigny, by the south-east side of the Trient, by the bridge of La Taillat and the hamlet of Guéroz. Thence he will take rail to Visp. The geological interest of the Valais increases, and its scenery is much under-appreciated. ‘The Jurassic crags, peaks and precipices on the north side after reaching Saxon, are very grand and wild. The tendency of the Jurassic rocks to slope up like a heavy swell at sea, from the north, and, so to speak, break like the crests of waves in stormy weather on the south, is well exemplified. On the south side at the base of the mountains we have a different series, lowest are anthracitic schists, then a long strip of dolomite, extending to beyond Sierre, then banks of quartzite, and high up micaceous and other schists. The flat valley, filled with old and recent alluvium, with the old Castles at Sion perched upon their craggy islands, the old moraines, especially about Sierre, would be excuse enough for the geologist to delay his journey at many points. On arriving at Visp we start at right angles to the Rhone valley, ascending through the Schistes lustrés of Triassic age ; then through some quartzite, and subsequently an occurrence of dolomite, then serpentine, which on the west side forms a not inconsiderable height. We then come upon mica and some chlorite schists, and, crossing a highly picturesque bridge, reach Stalden in less than two hours from Visp. Here we pass the night, well above the flies, queer odours, and generally doubtfully salubrious air of the Valais plain. Near Stalden are some notable stone-capped pillars and glacial detritus, resembling the well-known earth-columns of Botzen. Leaving the valley of §. Niklaus to the right, next morning we begin to mount the actual Saas-Thal, to the south-east. Mark the blocks of gneiss perched on the hill-side, and study the water- worn gorge, with its wooden bridges and torrent roaring at great depths. We come toa level with the bed of the stream, and find therein a considerable variety of pebbles of schists, gneiss, serpentine, gabbros, ete. In four hours we reach Saas-im-Grund, and again come, in the valley sides, upon a bank of dolomite, between the older metamorphic schists and the gneiss of the central mountain mass. J have seen sections well showing the contact metamorphisms of this dolomite. I should be much obliged if any geologist having the time would kindly examine the relations of these occurrences of dolomite to the other rocks. Saas-im-Grund itself is upon the edge of schists and gneiss just mentioned, and it is worth while to spend the rest of the day in this field-work, and in walking forty minutes up the west side of the valley to Saas-Fée (where there is a good Capt. Marshall Hall—Swiss Geological Excursion. 253 hotel), for the sake of the grand views of the Fletschorn and other noble peaks to the east, and of the great Fée glacier and surround- ing heights behind the village. In such case, and with a competent guide, it is not difficult to substitute a very interesting glacier walk for what I am about to describe as the next day’s work, by making across the Fée glacier towards the Allalinhorn, and working one’s way to Point 3150 métres on the map, and so down to the Mattmark inn. But if pressed for time, the traveller should walk or ride another three hours. In the bed of the torrents are beautiful specimens of the rocks of the country, in profusion. The rocks are schistose and gneissic on each side the valley. But on the west the Egginerhorn is of serpentine. Near Almagel is a gorge with waterfalls of great ‘picturesqueness. As we advance, the forests become more and more scanty, and the scene grows wilder. The path, near a small road- side chapel, brings you almost within reach of the end of the Allalin glacier. J remember that in the year 1848 or 1849, the ice was far over the existing track, and the old path was above the present one in consequence. The plain has scanty herbage, moraine gravel and streams wandering where I remember the Mattmark-see (now an insignificant sheet), which could then boast the dignity of a small lake. Blocks of serpentine become more and more abundant, close to the Mattmark inn is one which I roughly guessed to weigh some 5000 tons or more, called the Blauen-Stein. This characteristic upper valley, surrounded with precipices and glaciers, with a frowning desolate aspect, will much strike the traveller. The rough inn, with its ingeniously varied dinners out of scanty resources, and warm welcome, is at a height of 7000 feet above the Mediter- ranean, and well placed for mountaineering and field-work. It is also only some couple of hours or so from the Col of Monte Moro, and as horses or mules can be taken all the way from the railroad at Visp to Thaliboden, that is, one hour from the top, one of the sublimest views in all Europe is attainable without difficulty or fatigue. I know nothing in the range of the Alps, after some forty years of devotion to them, which in its way is more imposing, grander or more instructive than the view which bursts upon the traveller, of the cirque of precipices and glaciers of the Monte Rosa chain—to say nothing of blue Italy. But a very early arrival is generally necessary to enjoy this in completeness. Professor Bonney has written so much and well upon the Western Alps that I will not dwell upon their structure. But I will mention an exceedingly interesting day, or more, of work best done from the Mattmark inn. Although it is not actually in the considerable districts of serpentine which lie principally to the 8.H. and 8.W., the neighbouring heights are outliers of this mass. Also a rock of euphotide gabbro occurs within a morning’s walk, which has I think supplied most of the erratic stones of this rock which occur on the north side of Lake Leman, and at the junction of the Rhone and Arve, below the town of Geneva, whilst, as regards the gabbros found on the south side of Lake Leman, as, for instance, about Hvian, 254 Capt. Marshall Hali—Swiss Geological Excursion. I take it the mountains at the head of the Val d’Herens were their source, the widening Rhone glacier of old having spread out as it advanced. I come to these conclusions from microscopical examina- tion of rocks, erratic and not in situ. If we leave the inn betimes on a fine morning, we shall find the torrent at its lowest, and, crossing it by a wooden bridge of the roughest construction, we traverse a meadow, and at once begin to ascend a steepish zigzag up a ridge partly of rock, partly of old moraine. Chalets some 1000 feet above the valley would give shelter at a pinch, and milk when inhabited. An hour more up the Schwartzberg brings us to the Aeusser Thurm, which, as also the Inner Thurm a little further on, overhangs the Schwartzenberg Glacier on the S.E. side, and on the N.W. joins the Névé of the Allalin Glacier. We cross the latter, but, as it is in this part treacherous (owing to concealed crevasses), though not steep, we must either be three in number, roped, and experienced, or have a guide (and always a rope). In half an hour we shall reach the foot of a rock marked in the Swiss map 3150 métres (10,883 feet), and this is our mountain of euphotide. A climb without difficulty, but requiring caution, will in half an hour place us on its summit, and amongst its innumerable detached blocks we shall have found a ‘quantum sufficit’ of gabbros. Chloritic schists and serpen- tines characterize its surroundings, and the mass itself is far from being altogether euphotide. Now a geologist having started early and exploring the adjacent ridge, which leads up to the Allalinhorn, would fulfil the errand which took me there, but which I was unable to carry out from the rocks being concealed by an unusual quantity of snow in 1880. I was especially desirous to ascertain the exact relations of the presumably intrusive euphotide with the serpentine and other rocks surrounding it, and also to observe the effects of its contact with its neighbours. I failed ignominiously, though in other respects my scramble was delightful and its results satisfactory. There is another point—in the large Swiss map, a rock in the middle of the Allalin Glacier is marked 3368 métres. In that snowy year I think it must have been covered, or the glacier itself have previously increased in volume, for I could see nothing of it—the whole seemed névé. Now I much wish to know its nature, and should be grateful for specimens of it, and of the ridges leading up to the Allalinhorn and from the Inner Thurm to the Strahlhorn. Let the geologist be cautious as to falling stones, and bear in mind that serpentine, though a good solid rock, is perfectly awful to slip upon. In this skeleton of a tour the only occasions upon which a guide is at all necessary—though an intelligent mountaineer is always a useful and agreeable companion—is the scramble just described, and its alternative route from Fée. For these, and all walks in big mountains, a guide is a matter of prudence. I have now climbed for forty years, and still hold this mountaineering dogma. 1 Vide Mineralogical Magazine, June, 1883. C. Davison— Creeping of Soil-cap by Frost. 259 I have now briefly indicated a few of the innumerable matters of interest most prominent during a course up part of the great Rhone valley and across the various schists and other formations to the centre of the Western Alpine mass. I could go on, could keep my unfortunate geologist hard at work, week after week, over this hastily surveyed ground. But I should be writing a book! With regard to fossil remains. Switzerland is so bad a hunting ground that, unless a specialist: wishing for details of a particular formation, the paleontologist will grow discontented. But for the history of mountain formation, and—pace Heim—metamorphism, not a spot in this wonderful country but tells its story of one or other. And now I basely desert my traveller! If a scrambler, I advise him either to take the Weiss-Thor pass and sleep at the Riffel Hotel, or descend by the new Weiss-Thor pass which I first found in 1849, to Macugnaga. Whence, should the proposed excursion of the Geologists’ Association to Naples take place, he might join those who may have crossed the Simplon at Vogogna. If no mountaineer, he must even ride or walk down to Stalden by the way he came. Somehow or other he will I trust get home after much enjoyment. The geologist will find excellent official geological maps with memoirs and a large scale ordinary map (Siegfried) =5455 at Mon. Rouge’s, a leading bookseller in Lausanne. But it would avoid possible delay to bespeak them. TV.—On THE CREEPING OF THE SorILcAP THROUGH THE ACTION or Frost. By Cuartes Davison, M.A., Mathematical Master at King Edward’s High School, Birmingham. 1. The object of this paper is to show how the soilcap, or its upper portion, may creep down an inclined surface through the action of frost. The subject has also been discussed by Mr. W. C. Kerr in a valuable memoir, ‘On the action of frost in the arrange- ment of superficial earthy material,” ! published in May, 1881. I Fig. reproduce here one of the figures given by Mr. Kerr, as I cannot better describe the nature of the phenomenon which it is the aim of _ this paper to consider. “ During the Centennial Exhibition [at Philadelphia], Market Street was extended westward ..... and a hill of some twenty t American Journal of Science, 3rd ser. vol, xxi. pp. 845-358. 256 ©. Davison—Creeping of Soil-cap by Frost. feet was brought to grade in the process...... The rock is gneiss and mica-schist with hornblendic and chloritic strata, inclined at a high angle, and decomposed, for the most part, the entire depth of the cut [not more than three to four feet in the portion sketched], presenting a banded section of variously-coloured earths. The most striking and novel peculiarity of this section is shown in the sketch (Fig. 1, ante, p. 255), viz. the gradual drawing out,—attenuation of these coloured bands, as the parts of them in succession were moved down the slope” (p. 358). After remarking on the great depth of frozen soil in Canada and Labrador during their present winters, and on the still greater depth to which it must have penetrated during the Glacial period, Mr. Kerr says: ‘The alternate freezing and thawing of the saturated mass of decayed rocks . . . . would of necessity produce just the movement and settling which are described above. That is, this freezing and thawing would give rise to precisely the same move- ments of the mass, and of the particles inter se, as are seen to occur in the true glacier, differing only in amount. In other words, these masses were earth glaciers, and these deposits may be denominated frost drift, as distinguished from proper glacial drift” (p. 352). The majority of these deposits Mr. Kerr refers to glacial age; but, con- sidering the small thickness of that illustrated in Fig. 1, he remarks that “the probability is strong that it is of recent (present) origin, the existing climate of Philadelphia being equal to the production of such effects” (p. 353). It is not clear from this description how Mr. Kerr supposes the freezing and thawing to have acted in producing this movement of the soilcap. My first impression after reading his paper was that the water in freezing would, by its expansion, force the mass of loose earth bodily down the slope. This may be the case in certain parts of the-mass, but that the explanation cannot be generally true will, I think, be evident after I have described the way in which I believe the movement must as a rule take place, together with some of the experiments made to test the theory. 2. Imagine a layer of damp earth resting on an inclined surface, and exposed to the action of frost. The water in the interstitial pores will be frozen to a depth depending on the intensity and duration of the frost. If the particles of soil be not closely packed, the water will, in freezing, expand into the spaces between them, and the relative position of the particles may not be altered in consequence. But this cannot often be the case, for freshly-turned earth is soon rendered close and compact by a few showers of rain. The distances between the separate particles will thus as a rule be increased when the water between them is frozen. Now, the soil being compact and, except near the edges of the mass, continuous, the only direction in which expansion can readily take place is out- wards and perpendicular to the surface. Every particle of soil in the frozen layer will therefore be displaced from its original position along the line of the normal (or perpendicular) to the surface of the soil; and, if the water be equally diffused through- out, the amount of the displacement will be proportional to the C. Davison—Creeping of Soil-cap by Frost. 207 distance of the particle from the surface to which freezing extends. The more intense and lasting the frost, the thicker will be the frozen layer, and the greater the displacement of the surface particles. On the recurrence of warmer weather, the interstitial ice will be melted, and in melting will contract, and the particles will return, not, as they came, along the normal to the surface, but in a direction nearly vertically downwards owing to their weight; not quite vertically, however, because the adherence of each particle to its neighbours, by reason of the water between them, tends to bring it back towards its old position. The particles will thus after every frost and thaw occupy a lower position down the slope than they did before; and the whole outer layer of the soilcap will in this way creep slightly downwards, the creeping being greatest at the surface, and diminishing downwards to zero at the greatest depth to which freezing extended. 3. If all the particles descend vertically during the thaw, or at any rate in the same direction, it may be shown that a series of particles lying in a straight line will, after a single frost and thaw, continue to lie in a straight line, inclined, however, at a different angle to the horizon. Let a 3B (Fig. 2) represent the surface of the soil, cp the surface to which freezing extends. Let p be any particle of soil on the straight line qr. Its normal displacement, and therefore also its creep, PP’, will be proportional to the distance of pe from cD, and therefore to pr. Hence, the series of particles originally lying along the straight line qr, will, after the frost and thaw, lie along the straight line Q’k; and the effect of the creeping will be to bend the line qR 58 into the form QRS. 4, But, since during any winter or series of winters, there must be numerous frosts of different degrees of intensity and duration, and therefore penetrating to different depths, and since the surface layers of soil are affected by every frost, however slight, and in any one frost are more displaced than those below them, it follows that after any given time (including many changes of temperature across the freezing-point), particles lying originally on a straight line will in the end lie on a curved line with its concavity facing downwards. DECADE III.—VOL. VI.—NO. VI. 17 208 C. Davison—Creeping of Soil-cap by Frost. If the different frosts be of different degrees of intensity and duration, the resulting line will be curved throughout its whole length, down to the lowest depth to which freezing has extended. But if, as in colder countries than ours, the frost last through nearly the whole winter, and in different winters do not vary greatly in its depth of penetration, then the resulting line will exhibit a more or less sharp bend at the average depth to which the frosts are felt, and above the bend they will be fairly straight. Mr. Kerr’s section (Fig. 1) seems to me to agree remarkably with this latter deduction ; and it will be observed also that the bends are all at nearly the same depth, which ought to be the case when the surface is not very uneven. 5. The experimental evidence that I have been able to obtain, though less varied and complete than it might have been made in a colder country, is decidedly confirmatory of the above theory. The experiments were made in boxes inclined to the horizon, and in this respect the conditions were not quite natural, for the sides and bottom of the boxes, as well as the surface of the soil, were exposed to the cold. But the movements of the surface-particles near the middle of the boxes would not be affected by this. The method adopted, moreover, possesses several advantages, not the least being that the effects are more marked than they would be naturally, owing to the greater depth of frozen soil. — Two boxes, differing in form, were filled with damp, fairly compact, soil. The first (A) is, internally, 24; inches wide, 2% inches deep, and, at the surface, 13 inches long; the lower end is horizontal, the upper vertical; and the inclination of the bottom of the box and the surface of the soil is 32°. A straight bar of wood is firmly screwed to upright supports at either end of the box, so that its lower edge is parallel to the surface of the soil and at a distance of 14 inches from it. The other box (B), rectangular in form, is, internally, 15+ inches long, six inches wide, and 63 inches deep; and is inclined at an angle of 27°. A straight bar of wood is also fixed to the box, with its lower edge parallel to the surface of the soil and one inch from it. Fine pencil-lines are ruled on both bars in several places, perpendicular and parallel to the lower edges; and serve as reference-lines for the measurement of the dis- placements. I will now give an example of the experiments made with each box. 6. Experiment 1—(Box A). The index used to register the motion of the soil consists of a slab of sheet-lead, Zinch square, on two opposite sides of which are arms, one inch long and + inch wide. These are bent towards the centre of the slab, and, when they meet, bent again so as to be perpendicular to the slab. Part of a stout needle, 152; inches long, is bound tightly with strong silk between the projecting arms. The whole index weighs a little over three-fifths of an ounce. The index was placed so that the surface of the soil was level with the upper surface of the slab, and the soil was pressed closely all round it, so that there was no gap between the soil and the edges C. Davison—Creeping of Soil-cap by Frost. 209 of the slab. It was then left some days, and afterwards placed outside on the window-sill of an unused room, on the evening of January 3, 1889; and the distances of the needle-point from the lower edge of the bar and one of the lines perpendicular to it were carefully measured with the aid of a pair of bow-compasses.* The minimum temperature during the following night was 27° F. and the soil was evidently frozen through by the next morning. The needle-point had risen 14 mm. in a line almost exactly per- pendicular to the surface of the soil; and it remained in this position until the night of Jan. 7-8, when a thaw set in, by which the ice in the soil was entirely melted in about twelve hours. During this interval the position of the index was recorded several times ; and the displacements measured, though very small, showed that the -needle-point descended in practically a straight line, so as to end at the same distance from the lower edge of the bar as at starting, but 2 mm. further down the slope. The direction of descent was therefore not quite vertical, but approximately bisected the angle between the vertical and the normal to the surface of the soil. Also, the normal rise of the surface-particles was about 33; of the depth of the frozen soil, and their creep downwards about z$z of the same depth. At first sight, it seems possible that this creep may have been only apparent, and due to the weight of the index, which is of course much greater than that of an equal volume of soil. But I noticed carefully that, after the thaw, there was no gap between the lead slab and the surrounding soil; and this could hardly have been the case if the movement of the surface-particles had been very different from that of the index. The following experiment, however, appears to me to remove this objection, if it be one. 7. Experiment 2.—(Box B). An index, similar to that used in the preceding experiment, was placed on the surface of the soil, in order to measure its normal rise. Two fine grains, half a milli- metre in diameter, of very hard red drawing-chalk were also inserted into very small holes made in the soil to receive them. One of these was exactly in a line with the edge of a long pin (a lady’s hat-pin) fixed at right angles to the bar, and penetrating the soil. The other was just underneath the point of a similar pin constrained to slide in a straight groove perpendicular to the lower edge of the bar. Before the soil was frozen, the point of the pin was drawn up a short distance, and brought close down to the soil at the end of the frost and again after the thaw. . The box was put outside on February 9th, and by the 12th inst. the soil was frozen through. The needle point of the index had risen normally 32 mm., and the two red grains had also risen normally, and probably the same distance. Later on Feb. 12th the thaw began, and the interstitial ice was quite melted the next day. After the thaw, the needle-point of the index was found at ¢ mm. above its original distance from the lower edge of the bar, and 1 mm. 1 The measurements thus made are probably correct to one-eighth of a millimetre. 260 C. Davison—Creeping of Soil-cap by Frost. further down the slope. One of the red grains had crept # mm., and the other 1 mm. down the slope. The soil particles must therefore have descended along a line inclined at an angle of about 17° to the normal to the surface of the soil. The normal rise of the surface particles was about #5 of the depth of the frozen soil, and their creep about +45 of the same depth. 8. Now, if the creeping of the soileap through the action of frost were due to the expansive force of the freezing water urging the mass down the slope, it is clear that the downward movement should take place during the frost and not during the thaw ; but the experi- ments just described show that this is not the case, unless it be along the edges of the mass of frozen earth. Again, if this explanation were the correct one, the whole frozen layer at any point would be ‘displaced equally throughout its depth, and there would be a rupture of continuity between the frozen and unfrozen parts of the soileap. Hence, any line inclined to the surface would, after a succession of frosts of different degrees of intensity and duration, exhibit a series of breaks forming miniature faults parallel to the surface of the ground. And, if the principal frosts of every season penetrated to approximately the same depth, then, at that depth, the fault-displace- ment would be greatest. It need hardly be said that this inference is not supported by Mr. Kerr’s section given in Fig. 1. Both reason- ing and experiment are in favour of the view that creeping takes place by a normal rise during the frost and a more or less vertical descent during the thaw. 9. It would be interesting to determine, if we could, the length of time required for the production of the effects illustrated in Fig. 1, but the data are too imperfect to enable us to form more than a very rough estimate. Judging from the figure, the creep near the surface is on an average about three times the depth of the bends. If the amount of creeping of the surface particles be the mean of the values given by the experiments recorded above, namely, +7 of the depth of frozen soil, and if there be only one important frost and thaw eyery winter, then the time required may have been about 531 years. But the assumptions involved in making this estimate are too great to allow us to place any reliance whatever upon its accuracy. It is just possible, however, that it may indicate the order of magnitude of the real interval of time. 10. Lastly, the conditions which are most effective in producing the creeping here considered are neither those of a temperate climate, in which there may be many alternations of frost and thaw in one winter, nor those of an arctic or glacial climate; though probably nearer those of the latter than of the former. Other conditions being the same, the amount of creeping (measured by the product of the volume of soil moved into the average displacement down the slope) varies as the square of the depth to which the frost penetrates. Thus, if in one place, the soil be frozen to a depth of one foot, and, in another, to a depth of three feet, the creeping of the surface- particles in the latter will be three times as great as in the former, and the volume of soil affected also three times as great: hence the Dr. F. H. Hatch—The Wicklow Greenstones. 261 amount of creeping in the second place will be nine times that in the first. And it seems hardly possible that there should in any country be nine separate frosts in one winter each penetrating to the depth of one foot. On the other hand, in arctic countries, the soil is permanently frozen at acertain depth, and the amount of creeping then depends on the depth to which the soil is thawed during a comparatively short summer. We may conclude, therefore, that the amount of creeping will be greatest in that place in which the soil frozen in winter, and also thawed in the following summer, attains its maximum depth. V.—Nores on THe WickLow GREENSTONES. : By Frepericx H. Haron, Px.D., F.G.8. (Communicated by permission of the Director-General of the Geological Survey.) HE Wicklow greenstones occur in sheets and dykes intrusive in the Lower Silurian slates (the equivalent of the Bala beds of Wales) that lie to the east of the main chain of the Leinster granite. Like the Welsh greenstones, they are associated with acid lavas (felsites and keratophyres) and felspathic tuffs, although of slightly later origin than these. In a petrographical appendix to the memoir on Sheets 188 and 139 of the Map of the Irish Geological Survey, I have given some notes on the microscopical characters of the more important types. ‘These notes were based on sections made from rocks collected in June of last year. In November and December I had another Opportunity of visiting the ground, in company with my colleagues Messrs. Cruise and Clark ; and this visit threw fresh light on certain points not cleared up on the first occasion, especially with regard to the mechanically deformed greenstones, and also furnished me with an additional supply of material for microscopical investigation. As the publication of the memoir could not be delayed until this fresh material had been thoroughly worked out, perhaps I may be per- mitted to communicate in this place my results, coupled with a brief abstract of what has already appeared in the memoir. The Wicklow greenstones have this advantage over those of many other areas, that they present a greater variety in structure and com- position. Offering this attraction it is somewhat surprising that they have received such scant attention at the hands of the micro- scopist. The literature on the subject is indeed meagre, and may be disposed of in a very few lines.! Prof. von. Lasaulx,’ during a short visit to Ireland in 1876, collected some specimens which he described as diabase, diorite, and mica-diorite. ‘The Allport collec- tion in the British Museum contains a few sections of Wicklow greenstones. These have been described by Mr. Teall in his British Petrography.? 1 Professor Haughton gaye a brief description, with two analyses, of the West- aston greenstone as early as 1859 (Trans. Roy. Irish Acad. vol. xxii. p. 619); but I am referring to microscopical work. 2 «¢ Petrographische Skizzen aus Irland,” Tschermak’s Min. u. Pet. Mitth. vol. i. 1878, p. 441. 3 1888, pp. 249 and 266. 262 Dr. F. H. Hatch—The Wicklow Greenstones. In the notes appended to the memoir referred to above, the greenstones there described are arranged in the following cate- gories :—a. Quartz - mica -diorite; 6. Quartz -diorite and diorite ; c. Augite-diorite; d. Dolerite (diabase) ; e. Epidiorite (passing into hornblende-schist) ; and f. Serpentine. (a) Quartz-mica-diorite (the Tonalite of vom Rath).—A fine example of this rock occurs as an irregular boss, extending from Carrigmore to Westaston, 4 miles HE. of Rathdrum (Sheet 1380). The central portion of the mass is traversed by the road going from Rathdrum to Kilboy Bridge. The rock is remarkable for its granitoid appearance, the grain being moderately coarse and the colour light. Some parts of the mass are spangled over with lustrous six-sided plates of dark mica; while in others the mica is replaced by chlorite. At Carrigmore the mica occurs in thin bronze-coloured films, covering irregular patches of the rock’s surface. Under the microscope these patches appear as ophitic plates of a bright reddish brown colour. The component minerals of the rock are quartz, felspar (mostly plagioclase, but with a small quantity of orthoclase), biotite, a pale green hornblende, a few grains of colourless augite (malacolite), chlorite, and apatite. The quartz is abundant. It was evidently the last mineral to separate, since it fills the interspaces between the idiomorphic crystals of the earlier-formed minerals. Apatite is also present in considerable quantity ; and its six-sided acicular microlites are found penetrating all the remaining minerals. The chlorite has resulted from the alteration of the mica, the plates of which are sometimes surrounded by a border of chlorite, sometimes altered almost com- pletely into that mineral. (6) Quartz-diorite and diorite—An excellent example of quartz- - diorite occurs at Bologh Lower, three miles E. of Rathdrum. The rock is a medium-grained granitic aggregate mainly of felspar and quartz, but with some green hornblende and chlorite. Both mono- clinic and triclinic felspar are present, the former being fresher than the latter. The interspaces between the felspar-crystals are filled by clear quartz. Green hornblende occurs, sometimes in idiomorphic erystals that are evidently original, sometimes in granules and needles, imbedded in patches of chlorite, and then perhaps of secondary origin. In structure and composition the rock much resembles a horn- blende-granitite ; but mode of occurrence and association show that it belongs to the greenstone rather than the granite family. Similar rocks, but with less abundant quartz, occur near Cummer Place, six miles E. of Shillelagh. These-are true diorites. In all of them the effects of dynamic metamorphism are occasion- ally met with, in the shape of finely-granulated patches — the so-called “ quartz-felspar-mosaic” — resulting from a molecular rearrangement of the original felspar. ‘ (c.) Augite-diorite—This type is very common among the Wicklow greenstones. It consists essentially of plagioclase felspar Dr. F. H. Hatch—The Wicklow Greenstones. 263 and a pale variety of augite (salite or malacolite). Interstitial quartz is sometimes present; and there is a complete absence of ophitic structure, the augite occurring in isolated and often well- contoured crystals: both, points of distinction from dolerite. The felspar occurs in crystals giving lath-shaped sections and exhibiting the twin-striation characteristic of plagioclase. It is sometimes enveloped by patches of clear quartz, somewhat in the same way that felspar-lathes are enveloped by augite in the dolerites. Rocks of this character occur abundantly in the neighbourhood of Kilpatrick House, N. of Arklow. The exact localities are given in the memoir. (d.) Dolerite (diabase of the Germans).—The rocks considered under this head are composed essentially of plagioclase and augite, with a well-marked ophitic structure. The Wicklow type is entirely free from olivine, and passes by the addition of quartz, accompanied by a change in the nature and structure of the augite, into augite- diorite, to which it is naturally closely allied. The best representatives of this group occur in the neighbourhood of Arklow Head, where they are quarried for road-metal by Mr. Parnell. The dolerites pass readily into epidiorite; and even when the rock, examined under the microscope, appears, at first sight, to be quite unaltered, a narrow zone of secondary hornblende will, on nearer examination, sometimes be found fringing the augite-patches. But the more detailed discussion of these changes is reserved for the next section. . (e.) Epidiorite.—The rocks embraced under this head are dolerites that have undergone alteration under the influence of dynamic meta- morphism. Originally they were plagioclase-augite rocks; but, as a result of the metamorphism, the augite has been more or less com- pletely converted to hornblende. This mineral occurs in ragged patches, which in most cases still present the ophitic structure of the augite which it has replaced. Other new-formed minerals are chlorite, epidote, leucoxene, sphene and calcite. The leucoxene often presents elongated streaky forms, suggesting linear extension. Further evidence of mechanical metamorphism is to be found in the cata- clastic structure frequently presented by the felspar; in such cases the mineral loses its homogeneity and appears as a minutely granular mass, giving aggregate-polarization (‘felspar-quariz- mosaic”). In places where the movements have been great, the rock assumes a highly schistose character, and in such places a con- siderable proportion of the hornblende is often replaced by chlorite. All degrees in the mechanical metamorphism of a greenstone can be well studied in the Aughrim Valley, between Woodenbridge and Coatsbridge (Sheet 139). The altered rocks occur here in sheets, intercalated between the Lower Silurian beds, and are correctly represented on the Survey Map as a series of lenticular bands, striking N.E. and S.W. At the time when this ground was surveyed, however, the effects of dynamic metamorphism had not yet been recognized, consequently the schistose character of these 264. Dr. F. H. Hatch—The Wicklow Greenstones. rocks caused them not unnaturally to be regarded and mapped as tuffs (“ greenstone-ash”’).! In the smaller sheets the foliation is very striking, the whole of the rock being converted into schist; the thicker bands, however, are foliated only at the margin, i.e. near the junction with the slates. About one mile and a half west of Woodenbridge one of these larger bands has been well opened out by a quarry ; and the suc- cessive stages of alteration admit there of easy study. The central portion of the sheet is not foliated. It is composed of a granular ageregate mainly of plagioclase, and hornblende, secondary after augite. The hornblende is the ordinary green variety (actinolite), and shows pleochroism in bluish-green and yellowish-green tints. Ji occurs in patches, which, though often compact towards the centre, are usually bordered by a fibrous fringe. These patches are pene- trated by needles and prisms of turbid felspar, thus indicating the ophitic structure of the original augite. In rare instances a nucleus of augite still remains, thus removing all doubt as to the secondary nature of the hornblende. The presence of isolated patches of chlorite shows that hornblende does not represent the final stage of alteration ; for the chlorite appears to be derived from the hornblende, and thus to bear only a tertiary relation to the augite. Other secondary minerals are epidote, in granular aggregates, leucoxene, in white turbid grains after ilmenite, and calcite. The epidote is derived mainly from the felspar, the original crystals of which are replaced by a mosaic of minute granules of secondary felspar, doubtless a variety less rich in lime—such as albite, or oligoclase. A fibrous asbestos is developed between the slickensided joint- faces. Near the junction with the slates the rock assumes a marked foliated character. In thin sections made from this portion of the rock the hornblende appears in narrow fibrous bands, alternating with layers of a cryptocrystalline aggregate of felspar together with grains of original felspar. Secondary quartz is associated with the new-formed felspar, and chlorite with the hornblende. The chlorite increases in proportion to the amount of alteration, until finally we get a highly fissile lustrous schist, in which chlorite greatly pre- dominates.’ Some specimens of these highly altered schistose rocks, for instance one from a band two miles west of Woodenbridge, contain abundant grains of sphene, and it seems probable that this mineral has been produced by a molecular reconstruction of the turbid leucoxene derived from ilmenite. Some of the greenstone-bands that cross the Aughrim Valley are 1 According to Mr, W. M. Hutchings (this Macaztnz for February, 1889, p. 53) the same error has been committed in Cornwall, De la Beche having held certain ‘«schistose trappean rocks,’’ which Mr. Hutchings has proved to be mechanically metamorphosed greenstones,’’ for altered ash. * Similar alterations are described by Mr. Hutchings in the Tintagel rock (/oc. cit.), and by Mr, Teall in a greenstone occurring at Garth near Portmadoe (Brit. Petrog. p- 216). Miss C. A. Raisin—Greenstones & Schists of S. Devon. 265 prolonged in a south-westerly direction towards Croghan Kinshelagh. A specimen, collected from a spot one mile north of the summit of this mountain, proved, on examination with the microscope, to be a typical epidiorite. The rock forming the summit itself has under- gone more alteration. It has a marked foliated character, and consists mainly of chlorite and “felspar-mosaic.” Sphene is also present in abundant grains. . Specimens of epidiorite were also collected about a mile N. of Wicklow, on the §.W. side of Croghan Kinshelagh, and from a small atch of greenstone two miles east of Kilcavan House, to the east of Shillelagh (Sheet 1388). (f.)—In only one case was the occurrence of a serpentinous green- stone noted. My attention was drawn to this rock by Mr. Kinahan. A small patch of it occurs about half a mile west of the patch of epidiorite referred to above, two miles east of Kilcavan House, near Shillelagh. Unfortunately I was prevented by lack of time from visiting the locality myself, and the specimen examined was collected by Mr. Clark. The rock is of a variable green colour, and has the characteristically soapy “feel”? of a serpentinous rock. A microscopic section discloses the serpentine in colourless layers, associated with grains of opaque iron-ore and a finely granular substance resembling calcite or dolomite. The powdered rock, treated with hydrochloric acid, effervesces only on warming; it contains, therefore, as we should expect, the magnesian carbonate. The texture of the serpentine is well brought out between crossed nicols. It has rather the “netted” or “bladed” structure of serpentine derived from augite than the “lattice ”-structure peculiar to that mineral when produced by the alteration of horn- blende. Whatever may be the nature of the alteration, there can be little doubt that we have here the final product of the alteration of a greenstone (dolerite). As we have seen above, the usual course of the metamorphism of the Wicklow dolerites is, first, the formation of a hornblendic rock (epidiorite, hornblende-schist) and, finally, a chlorite-schist; but the case in point indicates that there are exceptions to this rule. 28, Jermyn Street, 8.W. VI.—Devontan GrReEnstones AND CHLOoRITE ScHists oF SovurTH DEVoN. By Miss C. A. Ratstn, B.Se. ie a paper published in the Devonshire Transactions for 1888 (p. 215), Mr. Somervail suggests the identity of the chlorite schists of South Devon with certain rocks to the northward. As this hypothesis (could it be established) would have a most important bearing on subjects of controversy, I took the opportunity in a few days this winter, to visit and collect from these localities, including the dyke nearest to Torcross. I was not rewarded by finding any striking similarity to the metamorphic rocks of the south. In that 266 Miss C. A. Raisin—Greenstones & Schists of S. Devon. series, the chlorite schists consist of clear and definite crystalline grains, among which I find felspar to be rare and have not yet certainly identified augite—while these northern greenstones are full of broken crystals of both minerals, together with viridite, dust resulting from the crushing, and a small amount of minute secondary hornblende and sericite (?), chlorite being generally rare, and often absent. The one rock is a true schist, the other nothing more than a schalstein. If Mr. Somervail ascribes the marked difference in character to more intense pressure, a very obvious difficulty would have to be met. As pointed out by Prof. Bonney, the chlorite schist exhibits at places not only a well-defined mineral banding, but also a cleavage cutting transversely across it, which appears to be in close relation with the general cleavage of Devonshire.! If, therefore, pressure metamorphism be invoked to account for the origin of the chlorite schist and its banding, the force must be relegated to an earlier period, and thus the rocks affected by it, even if originally igneous, cannot be of Devonian age. : Of themselves, however, these schistose rocks afford interesting study, as in the case of other west-country greenstones.? One type*® (from the coast near Redlap, and also from a quarry for road metal N.W. of Stoke Fleming), is clearly an ophitic dolerite,‘ but exhibits changes which have resulted from the crushing of the rock. Much of the augite is still very fresh and clear, but it seems to have been brittle, and to have broken along cleavage planes, forming fragments with sharp straight boundaries. Often there is a border of a horn- blendic mineral, partly an alteration product, although some is not unlike the serrate fringe of ‘secondary enlargement’ described by Van Hise,® having cleavage planes continuous with those of the original crystal. A fibrous hornblende, which is probably asbesti- form, also seems to have formed at places, where a fragment of augite has been drawn out in the shearing of the rock. Elsewhere, as Professor Bonney suggested to me, strands of a very pale viridite seem to be connected with remnants of augite crystals,’ and, in some cases, the viridite encloses small pieces, fragmental in outline, now con- verted into fibrous actinolite, which very probably have resulted from the crushing of a crystal of the pyroxene. Professor Bonney sug- 1 Q.J.G.S. 1884, vol. xl. p. 8, fig. 4, p. 22. ‘ 2 Q.J.G.S. 1876, vol. xxxii. p. 407, S. Allport. Q.J.G.S. 1876, vol. xxxii. p. 155, and 1878, vol. xxiv. p. 471, J. A. Phillips. Q.J.G.S. 1880, vol. xxxvi. p. 285, and 1886, vol. xlii. p. 392, F. Rutley. Brit. Petroer. J. J. H. Teall, p. 228. * Somewhat like the Carlion rock (No. 7) of Mr. Rutley, Q.J.G.S. 1886, p. 397. The augite resembles that of fig. 2, p. 898. + Cf. Mr. Allport, Q.J.G.S. 1876, p. 419. ° As, for example, in the Lizard gabbro and basalt. Q.J.G.S. 1877, vol. xxxiii. pp- 904, 907, Prof. Bonney, “On the Serpentine and Associated Rocks of the lizard.’ See also Q.J.G.S. 1885, vol. xi. p- 520, ‘On the so-called Diorite of Little Knott,’’? and Q.J.G.S. 1888, vol. xxxix. p. 256, ‘‘On Hornblende Picrite from Anglesey,”” Prof. Bonney. Also Q.J.G.S. 1878, p. 493, J. A. Phillips. ‘* Perimorphic’’ hornblende of Mr. Harker, Q.J.G.S. 1888, vol. xliy. p. 452. ° Amer. Journ. Science, 1887, vol. xxiii. p. 388, fig. 8; also U.S. Geol. Survey, 5th Rep. 1883-4. 1 Cf. Brit. Petrogr. J. J. H. Teall, pp. 216, 230. Miss CO. A. Raisin—Greenstones & Schists of S. Devon. 267 gested that this difference, in the results of the transformed augite, might be due to an admixture of the constituents of felspar obtained in the crushing, either from ophitic plates or from the surrounding mass. The felspar in the slide has been completely decomposed, and the ophitic plates can be identified mainly by their sharp out- lines, preserved within the surrounding augite. Rarely a granular crystalline aggregation seems to mark a former felspar now replaced. Thus this rock is actually in a condition of transformation, and seems to point out what may result from the crushing of an ophitic dolerite. Planes of schistosity have been formed, characterized by streaks of viridite, probably derived mainly from the pyroxenic constituent, and the larger films may mark the loci of what were once augite crystals. Secondary hornblende has formed by re- crystallization, along the exterior of original crystals, or from the shearing, possibly of an unmixed augite. A dusty and granular ground-mass, partly kaolinitic, has resulted from the powdering up of other constituents, including the greater part of the felspar. A slide from rock of a second type is crowded with plagioclase felspars, exceptionally well preserved, although they have been much broken and snapped by strains acting on the mass. Crystals of iron oxide are abundant, some being clearly ilmenite. The structure of this rock is difficult to interpret, but the felspars seem to have occurred as porphyritic crystals, and not to be pyroclastic. Professor Bonney has suggested to me, that the ground-mass might be that of a crushed glassy rock, possibly andesitic, and that the greenish mineral, which is abundant in it, might perhaps be best classed as a variety of palagonite. Mr. Rutley describes and figures certain rocks from Cant Hill, near St. Minver, which he believes have been derived from what was once a rather basic glass, and this slide from Redlap seems to have a ground-mass something like that of fig. 1—with broken felspar similar to that of fig. 3.’ I have not, however, recognized in these Devonshire specimens the vesicular structure, which the other rocks exhibited. In a third type of rock, the ground-mass seems to have been felspathic, sometimes crowded with well-defined felspars, which are now altered to a filmy mineral (? sericite). Porphyritic crystals can be traced, which have undergone an aggregate replacement. Other groups in the slide, consisting possibly of an intergrowth of quartz and felspar, with some calcite, might represent a similar porphyritic mineral, or they are possibly amygdaloidal, like that figured by Mr. Phillips.?, Sometimes associated with these, but distorted in form, are certain viridite or serpentinous strands, which may be examples of the crushed amygdaloids noted by Mr. Rutley, or possibly only the infilling of secondary cracks. They form the green films, which may be noticed on many of the schistose surfaces near Redlap, and in my specimens from that locality I searched in vain for any of the well-defined chlorite of the southern schists, with which mineral 1886, vol. xlii. p. 393, pl. xii. figs. 1, 3. eGase J.G.8. 1878, vol. xxxiv. p. 483, pl. xx. fig. 2. 268 Miss C. A. Raisin—Greenstones & Schists of S. Devon. the rocks are said to be charged.1_ Mr. Somervail may, however, allude to some other specimens from these cliffs (since I did not attempt to make an exhaustive examination of the place). But, even if chlorite occurs, as it does, although not to a large extent, in the dyke further south, its presence is a rather slender argument for the identification of the schist and the diabase, since it is one of the commonest secondary products in basic igneous rocks of any age or locality. I examined the associated sedimentary rocks at Redlap, and they are genuine phyllites of the ordimary Devonian character, with only the usual crystalline development of minute films along the lamin- ation.” If the greenstones were the equivalents of the chlorite rock of the south, it would be strange, that these associated phyllites should present such wide and well-marked differences from the mica schists. They exhibit effects of pressure metamorphism, even more strongly than the phyllites just north of the fault, which bounds the crystalline series, and yet they are totally unlike the mica schists in that series. In one of the phyllites near Redlap, the laminz are puckered up into undulations, across which at places extends a suc- cession of small brown films. These appear to have formed from a ferruginous infiltration, inserting itself and accumulating between the laminze, along the steeper slope of the waves. Just at this part, rupture has often taken place, thus forming an incipient strain- slip cleavage, marked only by a darker staining. The steeper slope of the undulations is almost universally in the same relative position —doubtless on that side towards which the thrust of the rocks was directed. F I must thank Mr. Somervail, for calling my attention to the deserted quarry of chlorite schist to the north of the Hall Sands streamlet, in consequence of which the boundary-line must be marked at that part of the valley as north of the stream.’ It is to be regretted, however, that Mr. Somervail does not withdraw his former untenable assertion, but attempts to renew it, by confusing together the correct indication of the boundary given by Professor Bonney on the coast, and any slight modification which I have to make in the direction I traced inland. The position on the coast would not be affected by the occurrence of the chlorite schist south of the valley, nor by this chlorite schist north of the valley. The hypothesis of a straight east-to-west line for the fault is quite gratuitous, since no 1 Trans. Devon Assoc. 1888, p. 224. ® Thus these rocks in the direction of their micaceous constituent would agree with the phyllites described by Professor Bonney from near Morlaix, Q.J.G.S. 1888, vol. xliv. p. 13, and would differ from those near Torcross, Q.J.G.S. 1884, vol. xl. pe La 3 See map Q.J.G.S. 1887, vol. xliii. p. 715. The dotted line marking the junction of phyllites and metamorphic rocks should probably cross the stream about east of the ¢ of Muckwell, before bending south-eastward or E.S.E. to the coast. This alteration does not, however, disprove the possibility that the fault may have determined the lower course of the valley, since there are no exposures which we can trust along the 400 yards between the quarry and the beach ; and also in a continued erosion along a fault, a portion of one rock may often be left adhering at some spot to the mass against which it was faulted. _ Prof. T. Rupert Jones—Ostracoda from Nova Scotia. 269 one attempts to draw such—how could the line in that case reach on the Salcombe estuary a position, which is considerably to the north of a line drawn due west from Hall Sands? In connection, also, with the suggestion, that the chloritic rock near the fault-line was a “ buffer, checking the northward spread of metamorphism,” ! I should like to ask, why was this duty neglected by the much larger and more extensive mass near Prawle Point, and that overlooking The Barr?—to the northward of which, in both cases, lie well-marked mica-schists. I might take exception to many other statements, but I should not be justified in thus occupying space, for they are matters of detail, compared with the suggested identification of the two series of rocks. These may have some resemblance to each other—though I should have thought it so superficial as not to mislead any practised observer; but even if there be a vague resemblance, due to their having had the same origin, they cannot, as I have shown, have been manufactured at the same epoch. VII.—On some OsrracopA FRoM THE Maxpou Coat-FIELD, INVERNESS Co., Care Breton (Nova Scotia). By Prof. T. Rupzrt Jonzs, F.R.S., and J. W. Kirxsy, Hsq. HIRTEEN specimens of black shale, crowded with Ostracoda, besides fish-scales, Anthracomye (?), and other small fossils, were sent in 1886 by Mr. J. F. Whiteaves, F.G.S8., Paleeontologist of the Geological Survey of Canada, for examination. They had been collected by Mr. A. H. Foord, F.G.S., of that Survey, in 1881. In these coal-shales the Ostracoda are very numerous as indi- viduals, but belong apparently to very few species of one genus. They are in a great degree similar to those mentioned in the Gxot. Mag. Dee. II. Vol. VIII. 1881, p. 95, and Dec. III. Vol. I. 1884, p. 308, etc., as occurring in the black coal-shales of the South Joggins, Nova Scotia. In the Mabou coal-fields we find :— 1. Carbonia fabulina, J. and K., very abundant. It is of rather smaller size than the Scottish forms figured and described in the Ann. Mag. Nat. Hist. ser. 5, vol. iv. (1879), p. 81, pl. 2, figs. 1-10. The innumerable minute Ostracoda imbedded throughout the shale seem to be small individuals of C. fabulina. 2. Among the foregoing is a variety larger than the Scotch speci- mens referred to, rather more oblong in outline, and with stronger marginal overlap, and a somewhat coarser punctation of the surface. It may be termed var. altilis (well-nourished). 3. Carbonia (?) bairdioides, J. and K., also occurs, but far less abundantly than C. fabulina. The specimens more closely resemble fig. 24, pl. 3, “A. M. N. H.” ser. 5, vol. iv. p. 38, than fig. 8, pl. 12 of the Gro. Mae., Dec. III. Vol. I. p. 359. Carbonia fabulina is abundant in the Upper and the Lower Carbon- iferous formations of Britain, wherever the conditions had been 1 Trans. Dev. Assoc. 1888, vol. xx. p. 217. 270 Prof. T. Rupert Jones—Ostracoda from Nova Scotia. favourable for the formation of Coal-shales,’ especially in the Lower Carboniferous series of Scotland. C. bairdioides occurs more rarely, but in strata similar to the above, in Scotland and Staffordshire. They both occur at the Joggins, on the shore of the Cumberland Basin, Cumberland Co., Nova Scotia, as noticed above. The geological features of Inverness County (Cape Breton), Nova Scotia, and the relationships of the strata are described in detail in the Geological and Natural-History Survey of Canada: Report of Progress, 1885 ; and Reports and Maps of Investigations and Sur- veys, 1882-83-84 ; including Report (H) on the Geology of Northern Cape-Breton, by Hugh Fletcher, 1884. Fies. 1-4. Carbonia fabulina, J. & K. Var. altelis, nov. Fig. 1. Carapace, showing the left valve, overlapped by the other valve at the margin. x 26. Fic. 2. Inside of the right valve. x 26. Fic. 3. Dorsal view of the carapace. Not set quite upright, but sloping a little. x 26. Fic. 4. Punctation of the surface; highly magnified. The Inverness Coal-field is treated of at p. 53H; and the Mabou Coal-basin at p. 61H. This is referred to as belonging to the «Lower Carboniferous” series at p. 53 H and on the Map (No. 14, 1884), accompanying Mr. Fletcher’s Report. At p.6 of the Report H, however, it is referred to the “‘ Middle Carboniferous,”’ which consists of ‘Conglomerate and Coal-measures”’ in that locality. The strata containing the specimens under notice are indicated in Mr. Fletcher’s Map (No. 14) as at the place where Mr. Foord collected fossils in 1881, on the shore about one mile and a half south of Cape Mabou,’ and about one mile north of the spot marked “Mabou Coal-mines ” on the same map. The “ Black Shales” of the Mabou Coal-measures are mentioned in the list of strata at p. 70 H, thus— «©12. Dark-bluish-grey, thin-bedded, calcareo-bituminous shale ; 1 See Quart. Journ. Geol. Soc. vol. xxxv. 1879, pp. 30 and 38; and Grou. Mae. Dee. III. Vol. I. 1884, p. 360. 2 The post-town called “Cape Mabou’’ is three miles east (inland) of Cape Mabou. Dr. H. Woodward—Turrilepas in Canada. 271 fish scales, teeth, coprolites, and spines, Cythere, Naiadites, Spirorbis. —2 feet. “13. Dark-bluish-grey, flaggy, concretionary, calcareous rock, with the same fossils.—2 ft. 6 inches.” There follow (14-29) other shales and shaley beds, more or less bituminous. At p. 71.H it is stated—'The black shales are those from which an interesting collection of fossils was made by Mr. Foord, of the Geological Survey, in the summer of 1881. In this collection the following forms have been determined by Mr. Whiteaves :—Naiadites (Anthra- coptera) carbonaria, Dawson; N. (Anthracomya) elongata, Dawson ; Entomostraca; Rhizodus lancifer, Newberry (scales); Cclacanthus (jugular plates) ; scales of two genera of Ganoid Fishes; also jaws and teeth of Fishes undetermined.” VIII.—On tue Discovery or TurRILEPAS IN THE Utica FORMATION (Orpovicran) oF Orrawa, CaNnaDa. By Henry Woopwarp, LL.D., F.R.S., F.G.S. R. AMTS interesting discovery has already been announced in a letter addressed to Mr. A. H. Foord, F.G.S., published in this Magazine (October, 1888). Mr. Ami now supplies a “Note” on the precise geological position of the beds in which the Turrilepas was found. Want of space, however, precludes us from giving the whole of his detailed observations, which are accompanied by a sketch section, here reproduced :— The following is a summary of Mr. Ami’s “ Note.” The Turrilepas was found in a band - of bituminous limestone cropping out on the right bank of the Rideau River, at the Rifle Range, near Ottawa. The pre- cise position of the beds (Lower Utica = about the lower part of the Bala Series),’ was ascertained by means of their fossil contents, which include an interesting Brachiopod—Siphonotreta Scotica, identi- fied and named by the late Dr. T. David- son, F.R.S. The calcareous and shaly measures characterizing the Lower Utica in this district, as exposed on the Rideau River, have a south-by-west dip of about 4°, and exhibit a portion of the south-western limb of a low, denuded anticlinal, which, however, affects the physical aspect of the country to a very small extent. The accompanying sketch is a diagram para aeaese= section of the rocks cropping out at the pisoram-section of rocks at Rifle Range rapids. The depth of section Rifle Range near Ottawa. is about 22 feet. 1 Mr. Ami regards them as equivalent to the Llandeilo of Craighead, Ayrshire. eT LeBel etl spend Lael ae yaar 272 Dr. H. Woodward—Turrilepas in Canada. (pp.) There are resting unconformably upon the Utica beds between 1 and 2 feet of Post-Tertiary sands and gravels, débris from the glacial clays or “till,” the “Leda clay,” and overlying sands of the Rideau Valley, a valley of denudation. (a.) These upper measures consist of thin-bedded, soft, at times hardened, black or dark brown, bituminous shales, holding crinoidal fragments associated with Lingula progne, Orthis testudinaria, Trocholites ammonius, Endoceras proteiforme, Triarthrus Becki, Asaphus Canadensis, etc. (0.) Thin Conularia-band, consisting of dark grey impure lime- stone, with Orthis testudinaria, Leptena sericea, Conularia Trenton- ensis, etc. (c.) Zone of Siphonotreta scotiea, Davidson. Band of black bituminous limestone, often shaly in character, and containing numerous fossils, including Lingula elongata, Discina Pelopea, Lep- tena sericea, Zygospira Headi, Conularia Trentonensis, Calymene senaria, Beyrichia oculifera, and Turrilepas Canadensis. (d, e, f, g-) Thin bands of black, grey, or dark brown calcareous — and bituminous shales, highly fossiliferous, except (g), which is “apparently destitute of fossils.” (h.) Light yellowish, grey weathering, argillaceous limestone bands, with shaly partings between the divisional planes of strati- fication, distinctly nodular in character and structure, disintegrating rapidly under atmospheric influence. Fossils :—Monticuliporide, Brachiopoda, Orthocerata, Bucania eapansa. 5 feet 5 inches. (i, k, l.) Thin bands of bituminous limestones and shales, from 3 to 10 inches in thickness, the last (1) holding Orthis testudinaria, Leptena sericea, Calymene senaria. (m.) Dark grey, bituminous, crinoidal limestone band with Lep- tana sericea, etc. This stratum dips north and south, being on the axis of the anticlinal referred to above. Thickness varying from 4 to 6 inches. (n.) Thin shaly parting, with Asaphus Canadensis. — (o.) Hard, compact, light-weathering, dark grey limestone band, holding Orthis testudinaria, Leptena sericea, Calymene senaria, Asa- phus Canadensis, Conularia Trentonensis. (p.) Compact, dark grey, impure limestone, bituminous and fossiliferous, holding Asaphus, sp. indt., crinoidal fragments, etc., preserved in a light, yellowish-brown, ferruginous matrix. Thick- ness, 8 inches. At a meeting of the Geological Society of London on June 7th, 1865, I described a new genus of Cirripedia from the Wenlock Limestone and Shale of Dudley, which I named Turrilepas (see Quart. Journ. Geol. Soc. vol. xxi. pp. 486-489, pl. xiv. figs. la—I). This Cirripede (or part of a Cirripede) had as many as four rows of asymmetrical plates, with more than eight plates in each row: the surface of each plate had a uniform sculpturing of fine, slightly waving, delicate, raised lines similar to those seen on the opercular valves of Balanus or of Pollicipes. As many as three or four different Dr. H. Woodward—Turrilepas in Canada. 273 forms of plates are known, these are arranged in linear series of similar plates, each series being strongly imbricate from below upwards, and so disposed that the edges of the contiguous series are alternate in position, and partially cover one another laterally. In the Supplement to vol. i. of Barrande’s great work “Systeme Silurien du Centre de la Bohéme,” part i. 1872, p. 565, the author describes a similar form under the generic name Plumulites, of which he records ten species, based on detached plates from beds in various localities in Bohemia, from D 1=Lingula Flags, to EH 2=Wenlock Limestone. Several of these plates closely resemble those from the Wenlock Limestone of Dudley ; the others, whilst agreeing in their orna- mentation, have the apex of the plates obtuse, and the ornamental lines near the summit circular and fenestrated. These may possibly have been terminal or opercular plates, the more pointed forms being the peduncular plates (see Q. J. G. 5. 1865, p. 488). In their “‘ Monograph of the Silurian Fossils of the Girvan District in Ayrshire,” etc., H. A. Nicholson, and Robert Etheridge, jun. (vol. i. 1880, fase. ii. pl. xiv. fies. 22-27, pp. 2138-215, and fase. iii. pp. 299-802, pl. xx. figs. 8-10) describe two new species of Turrilepas, namely, 7. Peachii, Hth. and Nich., and Z. Scotica, Rh. E., jun., from the Silurian of Girvan, Ayrshire. In their observations on Turrilepas one of these authors writes (p. 218) as follows:—“ The genus Turrilepas was established by Dr. H. Woodward for certain peculiar ovate-triangular plates from the Dudley Limestone, previously known under the name of Chiton Wrightianus, de Koninck. Dr. Woodward satisfactorily showed that these plates were more properly referable to a form of Cirripede allied to Loricula (and for which he proposed the name Turrilepas) than to Chiton, or to any other Mollusc. “Priority is claimed by M. Barrande for his term (Plumulites) on the plea of previous publication. For my own part, I hardly think the facts support M. Barrande’s claim. Dr. Woodward’s name was both proposed and published in 1865; and although the genus was certainly not defined in so many words, it was nevertheless founded on a well-known and perfectly defined fossil, and, what is more, was copiously illustrated. I take this to be satisfactory publication. it appears that M. Barrande had discovered similar plates in the Silurian rocks of Bohemia, and applied to them the name Plumulites, —a fact which was communicated (orally) by Prof. Reuss to the Imperial Academy of Science of Vienna, 18th February, 1864, and the name was published in a paper of the latter,’ but unaccompanied either by description or figure. So far as I understand the question, no description or figure was furnished by Barrande until the appear- ance in 1872 of the supplement to the first volume of his magnificent work on the Silurian System of Bohemia (already quoted). “T think, under these circumstances, that strict impartiality requires the adoption of Dr. Woodward’s name Turrilepas. Again, Messrs. Hall and Whitfield adopt Plumulites in preference to | Sitz. Berichte d. k. k. Akad, Wissensch. vol. xlix. p. 219. DECADE IlI.— VOL. VI.—NO. VI. 18 274 Dr. H. Woodward—Turrilepas in Canada. Turrilepas, on the ground that the latter was never characterized ; but my previous remarks equally apply in this case.’ (Nicholson and Htheridge, Girvan District, p. 214.) In Messrs. James Hall and John M. Clarke’s Geological Survey of the State of New York, Paleontology, Albany, N.Y. 1888 (4to. pp. 215-220, pl. xxxvi. figs. 1-19), the authors give figures and descrip- tions of eight species of Turrilepas from the Upper Helderberg and Hamilton groups= Devonian, Ontario and Ohio. One or two of these plates resemble somewhat Barrande’s Bohemian species and also plates figured by the writer from the Wenlock Shale, Dudley, but they are apparently all specifically distinct from the European forms, but with the same persistent ornamentation in which they all agree.’ The discovery by Mr. Ami of a new specimen of Turrilepas in so low an horizon as the Utica series, equivalent to our Llandeilo Flags, is particularly interesting, as the species recorded by Messrs. Hall and Clarke in Ontario are all from the much later Devonian formation. Turrilepas Canadensis, sp. nov., discovered by Mr. Ami in the Lower Utica series = Llandeilo, right bank of the Rideau River, Rifle Range, near Ottawa, Canada. Description of the Ottawa specimen :— Valve roughly triangular, right-hand border very broadly-rounded, but contracting inwards towards the apex; lower border sinuous in outline ; left-hand margin nearly straight, curving slightly towards the apex, which is deflected a little towards the right side ; the strie, which are slightly raised, are about 30 in number, very delicate and regular, and all follow the undulations of the lower border ; ihe carina dividing the right and left sides of the valve is very much nearer to the left-hand margin, with which it is also parallel nearly to the apex, the left side being only about one-third as wide as the right side; at about a third of the distance between the carina and the right-hand border of the valve and parallel to the carina is another apparent ridge (marked in the woodcut by a line of shading) ; this is really a flexure in the lines of growth and ornamentation, which is further emphasized by a fracture in the matrix containing the specimen exactly on this line. The valve of Turrilepas Canadensis measures six millimetres in height and five millimetres in breadth. In general form the Ottawa specimen agrees somewhat closely with 1 This ornamentation, as I have pointed out (see Grot. Mac. 1880, Dec. II, Vol. VII. p. 197) occurs also on the body-plates of the anomalous Cystidean, Ateleocystites, which is found in the same Wenlock Limestone of Dudley, and in the Trenton Limestone of Ottawa. Rev. O. Fisher—Secular Straining of the Earth. 275 one of those figured by the writer in 1865 (see Quart. Journ. Geol. Soc. vol. xxi. pl. xiv. fig. 17) ; but the Wenlock specimen is broader in proportion to its length, and the keel of the valve is straighter, and the general outline more angular than is the case with the Ottawa specimen. ; I propose for this new form the trivial name of Canadensis, and trust that before long, through the researches of Mr. Ami, we may become aquainted with many more examples of the valves of this very interesting and widely-distributed fossil. TX.—Remarxs on Mr. Davison’s Parer on Sucunar STRAINING oF THE HARTH. By ,Rzev. O. Fisuer, M.A., F.G.S. VERY important discovery was made independently by Mr. Davison, and somewhat earlier by Mr. T. Mellard Reade, when they demonstrated that, on the hypothesis of the earth having cooled as a solid body, there is within it a certain level, which is called by Mr. Davison the “ surface of zero-strain,” and for which Mr. Reade has adopted the term ‘level of no strain.” At this level compression ceases, and for a certain distance beneath it extension, or stretching of the layers of the globe, takes the place of compression. There are one or two points in Mr. Davison’s paper which invite remark, because they have an important bearing upon the geological aspect of the subject. He states that he has come to the conclusion that, after an interval of 174,240,000 years since the earth solidified, the depth of the surface, or level, of no strain ‘‘was or more probably will be” five miles. But for geological purposes what we want to know is, what the depth of this level may be at the present time. Now, on the assumption that the earth has cooled as a solid, this is easily calculated, without the need of any knowledge either of the length of time since solidification, or of the conductivity of the materials of which the crust of the earth is composed. The formula which gives the depth of the level of no strain within a few hundred feet is simple. It is: 6 temperature of ae es 3°1416\ temperature gradient ry eee Depth of level of no strain = The temperature gradient at present is known to be +; of a degree Fahr. per foot. The only quantity to be guessed at is the temperature of solidification, which Mr. Davison, following Sir Wm. Thomson, puts at 7000° Fahr. The radius of the earth in feet is 20,900,800. Working out the sum we then find that the depth of the level of no strain, on this hypothesis respecting the temperature, is at the present time 11,645 feet, or 2-2 miles. But 7000° Fahr. seems to be an excessive temperature for solidi- fication; and if we put it at 4000°, which seems more probable, the depth of this level at the present time would only be a little over half a mile. It must be remembered that the depth of this level 276 Memoirs—C. Barrois—Fauna of the Erbray Limestone. increases as time goes on, so that it is deeper down now than ever it has been before. It is obvious that the amount of compression which can be got out of a superficial shell certainly not more than two miles thick, and probably much less, the compression gradually diminishing and coming to an end at that depth, can have produced scarcely any appreciable folding. We must therefore look in some other direction for the cause of rock folding, thrust planes, and other phenomena of that nature. The probability is that the theory of the earth being solid throughout is incorrect. NOTICES Of MEHMOLES.- I—Rxcorps or tHe Grotocica, Survey or New Sovurm Wats. Vol. I. Part I. Department of Mines, Naser 1889. 8vo. 31 pp. and Plates i.—iv. S a significant indication of the increasing interest in geological science in New South Wales, it gives us pleasure to call attention to the first part of a new periodical, issued under the auspices of the Geological Survey of that colony, in which it is intended to record the discoveries and observations in the geology, palzontology and the mineral deposits of the country. The part just issued contains seven papers on a great variety of subjects, amongst which may be noticed ‘Notes on the Geology of the Barrier Ranges District and Mount Browne and Tibooburra Goldfields, by C. 8. Wilkinson, F.G.S., Geological Surveyor in charge’; ‘ Report on the Discovery of Human Remains in the Sand and Pumice Bed at Long Bay, near Botany,’ by T. E. David, F.G.S., and Robt. Etheridge, jun., and ‘On a Coral intermediate in structure between the Genera Lonsdaleia and Spongophyllum, etc.,’ by R. Etheridge, jun. Gadegrle I].—Faune pu Catcarre D’Erpray (Lorre InFirinure). Par Cuyarues Barrois. Contribution & Vétude du Terrain Dévonien de ’Ouest de la France. Extrait des Mémoires de la Société géologique du Nord, tome iii. Avril, 1889. pp. 884, pls. i.—xvii. ROM the beds of limestone quarried near the small town of Erbray (Loire inférieure) a comparatively rich fauna was obtained by M. Cailliaud in 1861, who compared it with that of the Bohemian étage F., the so-called third Silurian Fauna of Barrande, and it has since been regarded as the sole representative of this particular division in France. This conclusion is now called in question by Dr. C. Barrois, who has made an exhaustive study of the fossils from these rocks, and described and illustrated them very fully in the present memoir. The limestones yielding the fossils occur as discontinuous lenticular masses in a series of fine argil- laceous schists, which are unfossiliferous and estimated to be from 800 to 1000 metres in thickness. Dr. Barrois recognizes three distinct levels in the limestones, each marked by particular litho- aia ce cv peace Pa. 3 Reviews—A. Blytt—Displacement of Beach-lines. ie logical characters, corresponding to as many paleontological zones. Some of the beds are largely crinoidal; the fauna on the whole is very varied, and the number of species described is about 200, of which 57 are considered as new. Amongst the corals simple forms of Cyathophyllum, Zauphrentis and Amplexus predominate. A new genus, Briantia, is proposed for simple corals allied to Cyathophyl- lum, but with a solid external zone of considerable width. New species of Striatopora, Ccnites, and | 2 oRee Pvelaialeea) Cree) Nias Onaiosiardsasncns SS cgouse 1:2 OW sceee 17 Ohi coadseacsaesee WHOS. anaon Sine Fe -- Ke Oh a insarmie. cred ver Sty Was DOO) | snaoee 2°32 iia Oe eae ek traceny ny sssac ey deen — CAO ese sdancnesces TOV naMAp ees 36.5) lueeeee "15 Migs ON Bae Buteeedeegs ON) Soe hee ears CUB at ‘otacon 1:46 H,0 (by ignition) NBHID = poosae 1279 SPR eewses 9°86 100-07 100°64 99-84 No. 1, Residual clay resulting from the subaérial decay of trap rock from Wadesborough, N.C. No. 2, Residual clay resulting from the subaérial decay of Trenton limestone, from Lexington, Va. No. 3, Residual clay resulting from the subaérial decay of Knox Dolomite, from Morrisville, Ala. 1 From U. 8. Geol. Surv. Bulletins, No. 52. (To be concluded in our next Number.) 296 MM. Wilson and Crick—The Lias Maristone of Tilton. IJ.—Tue Lras Martstrone or Tirron, LeIcEsTERsHIre. By E. Witson, F.G.8., and W. D. Crick, With Palzontological Notes by E. Witson,, F.G.S. (PLATE IX.) HEN the new railway from Nottingham to Market Harborough was made, several instructive sections in the Upper and Middle Lias series were opened cut between the latter place and Tilton. Most of these are now covered up and grass-grown, but one of the best is still partially laid bare in the deep cutting at Tilton Station. This Tilton section has become one of considerable interest to the geologists of the Midland district, from the complete and characteristic exposure which it gives of the Marlstone Rock of Leicestershire in its fully developed and unweathered form, and also on account of the rich fauna which that rock, and in particular its top or ‘Transition Bed,’ has here yielded. The main purpose of this note is to present a list of these fossils with a detailed description of a few of them which are either new to the British Lias, or which have not hitherto received an adequate description. Before entering upon this part of our task, a very brief account of the stratigraphy of the district referred to will be desirable. A little to the south of Tilton Station the following section is exposed :— Upper Lias Suatzs: concealed in grass-grown slopes of the cutting, Ft. in. yielding a few fossils, e.g. Harpoceras serpentinum, Stephanocera “8 crassum, Turbo Theodort, Trochus Northamptonensis, Leda ovum, and Belemnites ... Aer =a ae 350 ... about 30 0 Mipptxz Lras: Marlstone Rock. ‘Transition Bed’? (Middle to Upper Lias); flaggy limestone, con- taining Harpoceras acutum, Amaltheus spinatus, Stephanoceras commune, St. annulatum, etc., Nautilus truncatus, Belemnites elongatus, B. paxil- losus, etc., Lima pectinoides, Pecten aquivalvis, etc., many Gasteropods, Pleurotomaria rustica, Cryptenia expansa, Trochus lineatus, Tr. ariel, Cerithium (?) confusum, C. ferreum, etc. Rhynchonella tetrahedra vay. Northampionensis, Terebratula punctata, and fragments of fossil wood 09to0 6 Bluish-green ferruginous limestone, finely oolitic ; "Han -poceras acutum, Ste- phanoceras commune, Pecten equivalvis, P. lunularis, Terebratula pune- tata, and Belemnites, in two blocks as dye) Bluish-green finely oolitic ferruginous limestone with irregular s seams of encrinital fragments; Pecten equivalvis, P. lunularis, and ” Belemnites, in three blocks ... 4 2 Bluish-green rock, becoming locally. a “jack?” ; 1 Pecten aequivalvis, Rh. tetrahedra, T. punctata and Belemnites .... 36 Greenish arenaceous rock with a ‘‘jack’’ in upper portion and nodular below; Rh. tetrahedra, T. punctata and Belemnites Bee 4 6 Greenish arenaceous rock with “ jack’’ in upper half, and nodular below ; ; Amaltheus margaritatus, Gresslya lunulata, G. intermedia, Pleuromya sp., Rh. tetrahedra, and T. punctata ... 200 636 500 Poe oy cls) 18 Ox Mippiz Lias SuHates with bands of sandstone and scattered limestone nodules, etc., Am. margaritatus, Protocardium truncatum, Monotis cygnipes, Avicula inequivalvis and Leda complanata, ete. son louis} (0) 18 feet exposed, increasing, as the beds rise, to the north. —— 1 ««Jack,’’ a quarryman’s term for a bed of marlstone made up of an agglomera- tion of the shells of Ethynehonella tetrahedra and Terebratula punctata. Decade III.Vol.VI.PI1.IX. . West,Newman imp. opoda. A,.3.Foord del. et lith. lias Marlstone Rock, Transition Bed & Upper Lias Gaster Tilton, Leicestershire +3 UMM. Wilson and Crick—The Lias Marlstone of Tilton. 297 The Marlstone Rock in the Tilton railway-cutting, lying beneath a thick capping of Upper Lias Shales, is a hard massively-bedded grey ferruginous limestone, in appearance something like the Marl- stone Ironstone of the Cleveland district of Yorkshire, but more finely- grained and duller looking, and containing also a much less per- centage of iron. The rock is traversed by numerous joints, and along these and also along the bedding-planes to the depth of a few inches on either side the carbonate of iron has been changed, under the influence of percolating waters, into the hydrated ferric oxide. Coincidently with this chemical change the greenish-grey stone has assumed a rusty-brown colour, so that, when first opened out, the face of the rock presented a very prettily checked appearance. A few years’ exposure to the atmosphere, however, has gone far towards toning down this variegation and covering the whole face of the Marlstone Rock with a uniform dull brown tint. So far as the Leicestershire area is concerned, the ‘Transition Bed,” at the top of the Marlstone Rock, appears to be confined to this single locality. This bed is remarkable for the numerous and varied organisms which it contains. Of these Harpoceras acutum is especially abundant, and characteristic of this horizon. Several Ammonites usually confined to the Upper Lias are here found asso- ciated with other forms characteristic of the Middle Lias, so that palzontologically the “ Transition Bed” must be considered as really transitional between those two series, notwithstanding that it pos- sesses the mineral characters of, and is welded to the Marlstone Rock. We have not therefore hesitated to apply to this bed the name given by Mr. H. A. Walford! and Mr. B. Thompson’ to a similar bed which lies at the top of the Marlstone Rock in Oxford and Northamptonshire. It is mainly, if not solely, from this thin stratum that the Ammonites, as well as the Gasteropods, which are so numerous at Tilton, have been obtained. The “Transition Bed ” may be examined in situ on a narrow ledge which projects a little from beneath the Upper Lias shales on the west side of the railway- cutting, and the best way to work it is to turn over and break up the slabs with a pick in wet weather, when the stone is softer and works much more readily. A small dip—about 1° §.E.—carries this bed and the Marlstone Rock beneath the line towards the south end of the cutting. The material taken from the Tilton cutting has been used to construct the embankment at East Norton, about three miles to the south. Here blocks of the Tilton Marlstone lie about in great num- bers. Under the action of the weather during the ten or twelve years which have elapsed since the line was made, the hard grey Marlstone Rock has been changed superficially into a comparatively soft brownish arenaceous ironstone, a change of the same kind, if not carried to the same degree, as that which, in the course of ages, 1 “On some Middle and Upper Lias Beds in the Neighbourhood of Banbury,” by Edwin A. Walford, F.G.S., Proc. Warwick Nat. and Arch. Field Club, 1878. 2 “Notes on Local Geology,”’ by B. Thompson, F.G.S., part x. ‘* The Junction Beds of the Middle and Upper Lias,” Journal Northants. Nat. Hist. Soc. vol. ui, p. 239, 1883. 298 MM. Wilson and Crick—The-Lias Maristone of Tilton. has converted this dense grey ferruginous limestone into a porous and friable rusty brown ironstone over such large areas, where it forms the surface rock, in Leicestershire and Rutland.! This soften- ing process has made it possible to extract a large number of fossils in a fairly complete state of preservation. The list of Tilton fossils here given is in large measure founded upon specimens thus obtained. It is therefore in many cases im-— possible to say with absolute certainty from what part of the Tilton section these fossils came; but as we find that the chief repository for the cephalous mollusea, at any rate, at Tilton, is the top or “Transition Bed,” we shall probably be pretty safe in assuming that most if not all of the similar organisms found in the Marlstone blocks of the Hast Norton embankment have been derived from that horizon. ; Going south from Tilton, the Marlstone Rock rapidly dies away. In the railway-cutting near Hast Norton Station it can still be traced as a concretionary bed two or three feet in thickness, whilst between Keythorpe and Hallaton it is less than one foot thick; and nearing Market Harborough, it locally disappears altogether. In the Hast Norton railway-cutting the grey clays of the “Com- munis zone” of the Upper Lias are exposed, and have yielded the following characteristic Upper Lias fossils :— Stephanoceras commune, Sow. Inoceramus dubius, Sow. ‘i crassum, Y. & B. Nucula Hammeri, Defrance. Harpoceras bifrons, Brug. », elaviformis, Sow. Belemnites subtenuis, Simpson. Serpula tricristata, Goldfuss. Nortonia (Purpurina) Patroclus, d’Orb. Paleontological Notes, by E. Wilson, F.G.S. Although it has fallen to my lot to undertake the critical paleon- tology connected with the subject, I have to acknowledge very considerable assistance from my colleague in this department of our joint work. Mr. Crick has not only collected the great majority of the fossils mentioned in the Appendix, but he has also identified the whole of them, with the exception of the Gasteropoda and the species which I have described. The success attending Mr. Crick’s re- searches in the neighbourhood of Tilton will be understood when I mention the fact that five years ago the total number of species which had been derived from the Marlstone Rock of the Leicester- shire district, including Rutland and 8.W. Leicestershire, did not exceed sixty, and that it is chiefly through his labours that this total has been increased to one hundred and ten.” Seeing that scarcely anything has been found in the Leicestershire district which has not also been found at Tilton, the Marlstone fauna of this single locality may be considered to fully represent that of the larger area referred to. 1 As an illustration of the effect of atmospheric action in producing this change, it may be mentioned, that under the railway bridges where the Marlstone ballast has been protected from the rain, the rock remains in practically the same hard state as that in which it was first quarried. * We are indebted to Mr. B. Thompson, F.G.S, of Northampton, for the privilege of inspecting his collection, and also for the loan of some of the most interesting of the fossils here described. MM. Wilson and Crick—The Lias Marlstone of Tilton. 299 Without further preface I proceed to the consideration of certain of these fossils which are either new to science, or to the British Lias, or which call for more complete description or revised nomen- clature. These fossils have all been derived from the Marlstone Rock of Tilton, Leicestershire, with the exception of the remarkable form first noticed, which is from the Upper Lias of East Norton, Rutland, and the peculiar interest of which must be my apology for noticing it in an essay not strictly dealing with Upper Lias paleontology. Norronta (Purpurina) Parroctus, D’Orbigny, 1847, Plate IX. Figs. la, 1b. 1847. Turbo Patroclus, d’Orbigny, Prodrome de Paléontologie, vol. i. 248 p. 248. Syn. 1850. Purpurina Patroclus, @Orb., Pal. Frang. Terr. Jur. vol. ii. Gast. pl. 329, fs. 9-11. P 5 Purpurina Philiasus, d’Orb., Pal. Frang. Terr. Jur. vol. ii. Gast. pl. 329, fs. 12-14, as Turbo Philiasus in the Prodrome, vol. i. p. 248. ; 1856. Littorina Patroclus, d’Orb. sp. Piette, Bull. Soc. Géol. France, 2nd ser. vol. xiii. p. 587. 1860. Hucyclus Patroclus, d Orb. sp. Eudes Desl. Bull. Soc. Linn. Norm. vol. v. p. 138. Ibid. Hug. Desl. op. cit. p. 135. non Purpurina subangulata, Mu. sp. Oppel, ‘‘ Der Jura,’ p. 386.' nec Turbo subangulatus, Munster, Goldtuss, Petref. Germ. vol. iil. p. 98, pl. 124, f. 5. Description.—Shell thin, elongate, conical, apex acute; whorls 9, angular, screw-like, with a very prominent acute and crenulated keel, situated about two-fifths of the breadth of the whorl from the anterior suture; the whorls slightly concave and gently sloping from the keel to the posterior suture, more deeply excavated and steeply inclined inwards to the anterior suture; the sutures are bounded posteriorly by a raised simple spiral, anteriorly by a finely granulated one; the base is convex and faitly inflated, bearing five equidis- tant raised granulated spirals, between the middle three of which are two simple ones; the whole surface of the shell is covered with very fine spirals; the posterior border of the last whorl rises near its termination at the aperture, so as to slightly embrace the penultimate whorl: aperture ovate, a little oblique, the outer lip has its inner border considerably expanded, and its outer edge is thickened by a very narrow rim, and digitated by the keel and basal spirals ; columellar border with a thin shelly deposit, columella outwardly twisted anteriorly; a narrow umbilical slit; anterior canal a broad shallow groove directed obliquely outwards, and effuse in front; posterior canal a narrow groove concealed beneath the over- lapping portion of the last whorl. Length, 16mm. Greatest diameter, 9mm. Spiral angle, 87° Sutural angle, 125°. Proportion of last whorl to whole shell, 7 to 16.? 1 Oppel was evidently mistaken in considering Turbo Patroclus, d’Orb., as the equivalent of Turbo subangulatus, Mu. * Figs. la, 1b, accurately represent this form, except that in Fig. 1a the shelly callus on the inner lip should have been shown to continue as far as the end of the posterior canal, 300 = MM. Wilson and Crick—The Lias Maristone of Tilton. Affinities.—D’Orbigny, in his Prodrome, gives a short diagnosis of a fossil, which appears to be rather widely distributed in the Upper Lias (étage Toarcien) of the centre and east of France, under the name Turbo Patroclus, and the same form appears in the “ Paléonto- logie Francaise” as Purpurina Patroclus. Although no description is given in the latter work of this or indeed of any other Purpurina, it is obvious, from the illustrations in the atlas, that we have here our Rutland fossil. Yet the figure in the “ Pal. Frang.” is remark- able in this, that with the identical form and ornamentation of the English fossil, it presents apertural characters which are very different. Instead of the contracted aperture, thickened outer lip, and anterior and posterior canaliculation, possessed by our shell, we see depicted a large oval aperture with rounded margins and without the trace of a groove or canal. Evidently whilst the body of the shell of Purpurina Patr oclus, D’Orb., is correctly delineated, the aperture is a beautiful but imaginary restoration; and the same observation will probably apply to Purpurina Philiasus, D’Orb., which is prob- ably only a more highly ornate variety of P. Patroclus. It is true | there are other Jurassic Gasteropods which have a spire and orna- mentation extremely like P. Patroclus, and which nevertheless belong to different groups, eg. Alaria and Pseudalaria; but the points of agreement between the fossil here figured and the _ illustration in the Pal. France. are, I hold, too precise to leave the above identification in doubt. It is to be noted also, that the name Purpurina given by D’Orbigny, implies that he considered these shells siphonostomatous, and this is expressed also in the original diagnosis of the genus, by that author in his “Cours élémentaire de paléontolgie,”—‘‘Ouverture pourvue en avant d’un tres étroit sillon qui remplace Vechancrure des Purpura.” It will not be necessary to give, at this point, the history of Purpurina, the more so as this subject was not very long ago treated in some detail by my esteemed friend Mr. W. H. Hudleston, F.R.S., in the pages of the GronogicaL Magazine,’ and still more recently in the first part of his valuable Monograph on the Inferior Oolite Gasteropoda.? It is sufficient for my purpose to point out that, whilst Jurassic paleontologists have rightly followed Deslongcbamps and Piette in restricting the genus Purpurina to forms possessing the general characters of Purpurina bellona, D’Orb., continental authors have been generally misled in their identification of P. Patroclus, D’Orb. as one of the Littorinide (an Eucyclus= Amberleya, or a Littorina), by the inaccurate figures in the Paléontologie Frangaise. What then are the true affinities of the shell under consideration? In the aggregate of its characters—the rather elongate spire, the aperture with an expanded outer lip, slightly enveloping last whorl, out- wardly twisted columella and clearly defined anterior and posterior canaliculation—this peculiar form seems to fall under the Cerithiidee. It will scarcely, however, come within the genus Cerithium or any other established genus of that family. In certain details of form and 1 Grot. Mac. Dec. II. Vol. IX. (1882), p. 11. 2 Pal. Soc. British Jurass. Gast. pt. 1. p. 8, and p. 83. MM. Wilson and Crick—The Lias Marlstone of Tilton. 301 ornamentation Purpurina Patroclus, D’Orb., is remarkably like, and is probably related to, the type of Mr. Hudleston’s new Jurassic genus Pseudalaria (Alaria) Etheridgi, Tawney, but the characters of the aperture are sufficiently different in these two shells to bring them under distinct generic groups. I believe it will be best to found a new genus for the reception of this remarkable Rutland fossil. I therefore, suggest for it the name Nortonia, in reference to the only British locality, Hast Norton, where it has at present been found. Nortonia might be briefly defined as a Cerithium with a very shallow anterior canal, and with eucycloid spire and ornamentation.’ Nortonia Patroclus is perhaps one of those “common forms” which serve to link together several very diverse genera, such for example as Cerithium and Pseudalaria on the one hand, and Amberleya and Purpurina on the other. I am indebted to Mr. Beeby Thompson, F.G.8., of Northampton, for the opportunity of examining this extremely interesting fossil. Geological Horizon and Locality.n—Upper Lias Shales, Railway- cutting, Hast Norton, Rutland. Crrituium (CERITHINELLA?) conFusum, Tate, 1875. Plate IX. Figs. 2, 2a. 1875. Cerithium confuswm, Tate, Gzou. Maa. Dee. II. Vol. II. p. 2065. I have several specimens of a highly elongate conical shell from East Norton, which answers to the description given by Tate of the above type. The state of preservation of these fossils is not suffi- ciently good to indicate with certainty their generic position. No figure accompanied the original description. I therefore give illus- trations from our Leicestershire specimens. Marlstone Rock, Tilton (Hast Norton embankment). CrERITHIUM FERREUM, Tate, 1875. Plate IX. Figs. 3a, 3b, 3e. 1875. Cerithiwm ferreum, Tate, Grou. Mac. Dec. II. Vol. II. p. 205. A number of shells have been obtained from the Marlstone Tran- sition-bed of Tilton, and from the East Norton embankment, which correspond with Tate’s type. No figures of this form having yet been published, I give illustrations from Tilton specimens to supple- ment the original description in the GronocicaAL MaGazInE. Marlstone Rock, Tilton (Hast Norton embankment and Tilton). CrriTHiumM costunatumM? Desl. 1842. Plate IX. Figs. 4, 4a. 1842. Cerithiwm costulatum, Desl. Mém. Soc. Linn. Norm. vol. vii. p. 199, pl. xi. figs. 12, 13. There is a single imperfect specimen from Hast Norton, of an elongate conical shell, which appears to represent the above type of As a general principle, no doubt, it is not safe to found a genus or even a species on a single specimen, and this prevents my giving a more precise diagnosis of Nortonia. In justification of the aboye genus-making however, it may be said, that the characters of N. Patroclus are exceedingly well defined, that our solitary specimen is apparently an adult shell, and is exceptionally well preserved, and that there is evidence of its maintaining its characters constant over a wide geographical area. 302 MM. Wilson and Crick—The Lias Marlstone of Tilton. Deslongchamps. The original illustrations are far from satisfactory : but the figured shell has a spire which is identical in its form and proportions, and apparently also in its ornamentation, with the above type, and I therefore make this identification with some con- fidence in its accuracy. Marlstone Rock, Tilton (Hast Norton embankment). CeritHium I~mMinstERENsIs, Moore, 1866. Plate IX. Figs. 5a, 56, 5c. 1865-6. C. Ilminsterensis, Moore, Proc. Somerset Arch. and Nat. Hist. Soc. vol. xi. p. 200, pl. iv. s. 12, 12a. There are a number of specimens of a shell which agrees in its general characters with Moore’s type. These shells are twice the length of the type, with the same number of whorls, and also differ from C. Ilminsterensis, Moore, agreeing with C. Dayii, Tate, in having four rows of subspinous encircling costule instead of three in each whorl. These small points of difference do not, however, seem to me to be characters of specific value. Marlstone Rock, Tilton (Hast Norton embankment). PsEUDOMELANIA (CHEMNITZIA) Brannoviensis, Dumortier, 1869. Plate IX. Figs. 6, 7. 1869. Chemnitzia Brannoviensis, Dumort. Etudes Pal. sur les Dépdts Jurass, du Bassin du Rhone, pt. iil. p. 218, pl. 27, f. 11. The Marlstone blocks on the Hast Norton embankment have yielded us a number of shells which, although of much smaller dimensions, seem to agree with this type of Dumortier’s. Seeing that this fossil has not hitherto been recorded from the British Lias, the following description and the illustrations here given may be of interest to the students of the English Jura. I adopt the generic designation of Pictet and Campiche as applicable to this form. Description :—‘ Shell conical, short, imperforate: spiral angle regu- lar; whorls eight, flat or very slightly convex, covered with trans- verse lines of growth, forming thick irregular obscure plice, which give origin close to the suture posteriorly, to a series of nodules, slightly scalariform. Aperture high, oval, very oblique, without callosity over the columella. The last whorl occupies nearly half the total height. Length to width 82: 17. Spiral angle 438°.” Hast Norton specimens give: Height 22 mm.; Diameter 11 mm.; Spiral angle 42°. Marlstone Rock, Tilton (Hast Norton embankment). PsEUDOMELANIA (PHASIANELLA) TURBINATA, Stoliczka, 1861. : Plate IX. Figs. 8, 9. 1861.- Phasianella turbinata, Stol., Gast. und Aceph. der Hierlatz-Schichten, Jahrbuch der k. k, Reichsanstalt (Wien), vol. xliii. p. 177, pl. iii. fs. 1. 2. Like Ps. Brannoviensis, this is fairly common at Tilton. The genus Pseudomelania is suggested as a more fitting generic appella- tion for this form also. Marlstone Rock, Tilton (Hast Norton embankment). MM. Wilson and Crick—The Lias Marlstone of Tilton. 303 Turgo rucirera, Moore, 1867. Plate IX. Figs. 10a, 108, 11. 1867. Turbo rugifera, Moore, Middle and Upper Lias, Proc. Somerset Arch. and Nat. Hist. Soc. vol. xiii. p. 209, pl. vi. figs. 23, 24. Syn. ,, Turbo coronatus, Moore, Ibid. p. 209, pl. vi. figs. 21, 22, 22*. Syn. ,, Pleurotomaria costulatum, Moore, Ibid. p. 208, pl. v. figs. 12, 13. Fresh description.—Shell turbinated, conical, umbilicated, apex acute; whorls 6-7, convex, narrow, with a broad flattened area bounding the sutures anteriorly, ornamented by sharply raised spiral lines, of which there are six or seven on the penultimate whorl, crossed by numerous fine, regular, close-set oblique radial lines, which raise the spirals into neat granulations at their decussations; base very slightly convex, umbilicus deep and generally large, with a squarely angulated and crenulated edge; aperture nearly round and nearly free from the last whorl; outer lip thin, inner lip with a lunate shelly expansion anteriorly. A few fine spirals may mark the circumference of the base, and very faint concentric striz are sometimes discernible between these and the centre of the base, over which the fine radial lines are continued in flexuous curves. Height 9 mm.; Diameter 8 mm. to 9 mm.; Spiral angle 60° to 92°. Note.—There is evidently considerable variation within the limits of this species, and different appearances are presented by different individuals according as the spire is more raised or depressed, and according as the varying relative strength of the spirals gives a rounded or an angulated appearance to the whorls. It is not there- fore surprising that the late Charles Moore made three species out of the three variable specimens of Turbo rugifera which he obtained from the Middle Lias Marlstone of Ilminster. The specimens collected by Mr. Crick at East Norton serve to link these three forms together, and indicate that Turbo rugifera is the true type. Having carefully examined the type of Pleurotomaria costulatum, Moore, in Bath Museum, I see no reason for considering that shell a Pleurotomaria. It shows no trace of a sinus-band, and appears to be only a highly granular and somewhat squarely-keeled example of Turbo rugifera, Moore. Turbo coronatus also is only a more fully grown shell of the same type, with the difference that the greater prominence and coarseness of one of the spirals gives its whorls a coronated aspect. Marlstone Rock, Tilton (Hast Norton embankment). TROcHUS ROTULUS, Stoliczka, 1861. Plate IX. Figs. 12a, 120, 12c. 1861. TZrochus rotulus, Stol., Gast. und Aceph. der Hierlatz-Schichten, Jahrbuch. der k. k. Reichsanstalt (Wien), vol. xliii. p. 178, pl. i. f. 7. In the Journal of the Northampton Natural History Society for 18831 Mr. EH. A. Walford, F.G.S., quotes this fossil from the Marl- stone Transition-bed of Aston-le-Wall and Appletree, and gives an illustration (loc. cit. fig. 5), which can however hardly be con- sidered a satisfactory representation of this very elegant little shell. I trust the figures here given may be more successful. Trochus 1 Journ. Northants Nat. Hist. Soc. vol. ii. (1883) p. 296, pl. fig. 5. 304. MM. Wilson and Crick—The Lias Marlstone of Tilton. rotulus, Stol., must not be confounded with Trochus ta Moore, from which it 1s quite distinct. Marlstone Rock, Tilton (Hast Norton embankment). PLEUROTOMARIA HELICINOIDES, Roemer, 1836. Plate IX. Figs. 13a, 130. 1836. Trochus helicinoides, Roemer, Die Verstein. des Ool.-Gebirges, p. 150. pl. x1. f. 13. Syn. 1867. TZrochus carinatus, Moore, ‘“ Middle and Upper Lias of the South- West of England,’ Proc. Somerset Arch. and Nat. Hist. Soc. vol. xiii p. 207, pl. 4, fs. 24, 25, non Turbo canalis, Minster, nec Plewrotomaria helicinatdes. Roemer, of Tate. Whilst agreeing with Mr. Ralph Tate, F.G.S.,* that Trochus carinatus, Moore, is a Pleurotomaria, and (in all probability) identical with Trochus (not Turbo) helicinoides, Roemer, I cannot go so far as to admit that these are the same as Turbo canalis, Minster—a Pleurotomaria truly, but a different species I maintain, to the above. The figure entitled Pleurotomaria helicinoides in the Yorkshire Lias is, I consider, an illustration of ‘ Zurbo’ canalis, Mi., and not of ‘Trochus’ helicinoides, Roemer. The following descriptions and the accompanying figures of Tilton specimens will indicate the chief points of difference between these two forms. Pleurotomaria helicinoides, Roemer (assuming this to be the equivalent of Trochus carinatus, Moore), is a smooth and even polished shell, with very clean cut and angular sculpturing; the whorls have an acute keel anterior to the middle line; on this keel is placed the sinus-band, which is bounded by a single rather widely-spaced raised line on each side; from the sinus-band the whorl! falls verti- cally in front to the anterior suture, and slopes gently back in a single concave sweep to a raised line or faint keel close to the posterior suture; the last whorl bears a third angulated keel ante- riorly, bounding the broad vertical area below (i.e. anteriorly) ; the shell is covered with very fine curved lines of growth; the base is only slightly convex, smooth, but bearing a few very fine acute concentric lines either limited to the outer part or continuous to the centre; there is a very small umbilicus; the aperture is transversely ovate, a ill-defined columella. Height, 8 mm. ; ereatest diameter T mm.; Spiral angle convex, about 70°. Marlstone Rock, Tilton (East Norton embankment). Prievrotomarta (TurBo) cAnatts, Minster, 1848. Plate IX. Fig. 14. 1848. Turbo canalis, Pe. gous, Petref. Germ. vol. ii. p. 95, pl. 198, figs. 12a, 0. Syn. 1878. Plewrotomaria helicinoides, Roem. sp. Tate, non Roemer, ‘‘ The York- 1 shire Lias,’’ p. 338, pl. x. figs. 7a, 70. Whilst possessing the same general form of Pl. helicinoides, as above described, this shell presents rounded instead of angular contours, is far from smooth, and differs in its proportions as well as in its ornamentation. In Pl. canalis the keel bearing the sinus- band is situated posteriorly rather than anteriorly to the middle line, 1 “The Yorkshire Lias,’’ by Tate & Blake, p, 338, pl. x. fs. 7, 7a. H. H. Howorth—Circumpolar Lands. 305 and is less angular, and the sinus-band is bounded by two much more closely set lines than in Pl. helicinoides. There is indeed a similar broad vertical and nearly smooth area below (anterior to) the sinus-band ; but, excepting this, the whole shell from the apex of the spire to the centre of the base is covered with regular and prominent rounded spiral lines; two of these spirals situated in the middle of the sloping posterior portion of the whorls are more raised than the rest, and make the whorls appear more convex; the periphery of the last whorl also is rounded. Very slender curved radial lines may be discerned throughout the shell with the aid of a lens; but these are fainter than in Pl. helicinoides, and almost con- cealed by the spirals. The base is slightly convex; a very small, if any umbilicus; columella indistinct, and the aperture generally very like that of Pl. helicinoides. Height 85 mm.; width, 7 mm. ; Spiral angle convex, about 75°. Marlstone Rock, Tilton (Hast Norton embankment). EXPLANATION OF PLATE IX. Fic. 1. Nortonia Patroclus, @ Orb., Upper Lias, Railway cutting, East Norton, Rutland. a. Front view; 0. back view. Enlarged twice. », 2. Cerithium (Cerithinella ?) confuswm, Tate, Marlstone Rock, Tilton (Kast Norton Embankment). Enlarged one and a half times. a, Whorl further magnified. », 98. Cerithium ferreum, Tate, Marlstone Rock, Tilton. a. Front view; 6. back view. Enlarged one and a half times. c¢. Whorl further magnified. », 4. Cerithium costulatum ? Desl., Marlstone Rock, Tilton (Kast Norton em- bankment). Enlarged one anda half times. @. Whorl further magnified. » 0. Cerithium Llminsterensis, Moore, Marlstone Rock Tilton (Kast Norton Embankment). «@. Front view; 6. back view. Enlarged one a halt times ; ¢. Whorl further magnified. » 6. Pseudomelania Brannoviensis, Dumort., Marlstone Rock, Tilton (Hast Norton embankment). Front view. Enlarged one and a half times. », 1. Lbid. From another specimen. Back view, similarly enlarged. 8. Pseudomelania turbinata, Stol., Marlstone Rock, Tilton (Kast Norton Em- bankment). Front view. Enlarged one and a half times. », 9. Ibid. From another specimen. Back view, similarly enlarged. », 10. Turbo rugifera, Moore, Marlstone Rock, Tilton (Kast Norton Embankment. a, Front view; 0. back view. Enlarged twice. », ll. Ibid. Base, from another specimen, with an exceptionally large umbilicus. Similarly enlarged. », 12. Trochus rotulus, Stol., Marlstone Rock, Tilton (Kast Norton Embankment). a. Front view; 8. back view. nlarged twice. c. Whorl further en- larged. ng Be pana helicinoides, Roemer, Marlstone Rock, Tilton (East Norton Embankment). a. Front view; 4. back view. Enlarged four times. », 14. Pleurotomaria canalis, Munster, Marlstone Rock, Tilton (East Norton Embankment). Enlarged three times. (Lo be continued.) II].—Was THERE Aan Arctic OcEAN IN THE MammotH Periop ? By H. H. Howorrn, Esq., M.P., etc., etc. HE convergence of opinion is now so strong that the climate of Siberia in the Mammoth age was sufficiently temperate to enable trees to grow where only the bare tundra is at present found (if it does not necessitate our extending the forest zone at least as far north as the Liachof Islands), that it becomes at once interesting DECADE III.—VOL. VI.—NO. VII. 20 306 H. H, Howorth— Circumpolar Lands. and important to consider under what conditions such a result would be forthcoming. The fauna of the polar lands is so uniform in all longitudes that they constitute one of the best-defined zoological provinces; a province to which the name Circumpolar or Panarctic has been given. So far as our evidence goes, the solidarity and identity of forms which now mark the circumpolar lands was shared in the Mammoth age by a considerable zone south of this area, a zone now constituting the greater part of the Palearctic and Nearctic provinces of Mr. Sclater. If we are to judge by the remains which we can examine of the Mammoth and its contemporaries the Musk Sheep, the Bison, the Horse, the Elk, the Red Deer, the Reindeer, ete., etc., from the Old and the New World, there were not in the Mammoth age the distinctions which now mark off the mammals of North America from those of Northern Asia, and the panarctic and nearctic regions were then condensed into a fairly homogeneous zoological province. This means of course that there must have existed in the Mam- moth age a bridge over which the mammals at least could travel between the Old and the New World and vice versdé. Such a bridge would enable the animals to intermingle, and prevent isolation, which is the recognized causa causans of divergence of forms. If this be granted, and I cannot see how it can be contested, we have next to discover where this bridge was situated. In my work on the Mam- moth J have followed in the footsteps of Mr. A. Murray, and en- larged his reasons for believing that it is quite impossible to suppose that this intermigration took place across the ice of Bering’s Straits. Tn addition to the arguments there adduced, I would remark that if Bering’s Straits were frozen over, it could only be under climatic conditions, when the Mammoth and its companions would find it impossible to exist on the land on either side of that water-way ; and if we postulate (as the facts compel us to do) a comparatively mild winter climate in the Tchukchi peninsula and Alaska when the Mammoth lived, then we cannot also postulate that Bering’s Straits were at the same time closed by thick ice such as would alone afford a highway for the animals to travel over. The notion that the intermigration took place over the ice of Bering’s Straits is in fact an immature and very superficial one. Putting aside a highway of ice across Bering’s Straits, we are bound to postulate a land communication between Asia and America at this period, and the question is, where this bridge was planted. It is quite clear that, wherever placed, it must have connected the Mammoth area on the one continent with the Mammoth area on the other, and since, the Mammoth, so far as we know, did not live in Japan, but was there replaced by another species of Hlephant, this communication must have been north of Japan. Inasmuch as neither the Tichorhine Rhinoceros, nor the Hyena, nor the Great Ox (Bos primigenius), Whose remains are all found along the latitude of Central Siberia (the Rhinoceros occurring as far north as the river Wilui), have ever been found in America, and, so far as we know, H. H. Howorth— Circumpolar Lands. 307 they never reached that continent, it is prima facie almost certain that the connection required must be found further north than these latitudes ; and this is confirmed when we compare the living mam- mals and birds of Japan with those of America. This makes it probable that the required bridge was in fact situated at a high latitude, where we must suppose that the con- ditions, although compatible with forest growth and consistent with the Mammoth, the Hlk, the Red Deer, and other forest- frequenting animals finding food, etc., were too severe for the Rhinoceros, the Hyzena, and the Great Ox to find congenial quarters. That it was situated here is further proved by the very close re- semblance, if not identity, of the living Rocky Mountain Sheep with that of Kamschatka. Turning to another class of evidence. I have elsewhere adduced arguments to show that the mammal remains found in the New Siberian Islands and in the Bear Islands (the former 250 miles away from the Siberian mainland) are the remains of animals which actually lived where these remains occur. These islands and the opposite coast are at this moment rising from the sea, and laying bare new sand banks containing heaps of Mammoth and other bones, which are so fresh and sharp and unweathered, that it is clear they have been lying where the animals died. All this makes it exceed- ingly probable, if not certain, that when the Mammoth lived the Siberian Islands, the Bear Islands, and probably also the small islands discovered in the Jeannette Expedition, on which semi-fossil bones were found, formed part of the mainland, and that the more or less temperate conditions which I have postulated of Northern Siberia then extended at least as far as these islands. This is very interesting, because, if we postulate so much, we have no difficulty in going further. The deepest soundings found by Nordenskiéld and other explorers between the Siberian Islands and the mainland are about 22 or 25 fathoms. This, again, is the greatest depth which has been sounded in the northern part of Bering’s Straits between America and Asia; so that, if the movement of elevation which united the New Siberian Islands to the mainland was as general and widespread as the present elevatory movement in the Arctic regions is, then it follows that the uniting of the Siberian Islands with the mainland was accompanied by the bridging over of the space between North-Eastern Asia and Northern Alaska; thus forming an isthmus between the two continents. We may perhaps go even further, and say that, inasmuch as the present elevatory movement over the whole Arctic basin is general and wide- spread (as I ventured to show many years ago in a paper read before the Geographical Society, which was reprinted in the Arctic Manual), and inasmuch also as the general evidence goes to show that the portion of the Arctic basin east of Nova Zembla is shallow, it follows as very probable that a large portion of what is now occupied by that sea was in the Mammoth age dry land, and not only dry land, but land upon which trees would grow, and therefore within the climatic zone marked by forests. 308 J. G. Goodchild—Formation of Coal-seams. This conclusion is largely supported by the fact that Maclure and other Arctic explorers actually found remains of some fossilized trees of species still living in North America in some of the islands of the Arctic Sea east of the River Mackenzie. These trees were rooted in the ground and in sité, and grew therefore very far to the north of the present range of trees in the New World. The reasoning I have ventured to adduce is based upon empirical evidence. If, as it seems to me, it is well founded, then it follows that the circulation of ocean currents in the Northern Hemisphere must have been entirely different from what it is now, since there was a barrier preventing the outgoing Arctic current from passing through Bering’s Straits. Such a change must have materially altered the climate. Secondly, the climate must have been very largely modified over the whole of Northern Asia in another and more direct way ; for the north winds which are now so keen and killing, since they come straight from the great northern reservoir of ice which is never at a higher temperature than 82°, would then come from a land of grass and trees, and be correspondingly softened. This would have a very great effect upon the Siberian climate in the direction of making it consistent with the Mammoth, the Horse, and the Bison finding food and shelter in the area between Alaska and Northern Asia. Pro tanto this is a solution of the question of how to account for a mild climate in these high latitudes. It does not, however, exhaust the preblem, and other causes remain, which perhaps you will let me discuss on another occasion. TV.—On some Mops oF Formation oF Coat-SEAMs. By J. G. Goopcnirp, F.G.8., H.M. Geol. Survey. (Based upon a paper read before the Royal Physical Society, Edinburgh, on the 17th April, 1889.) HE commonly-received theory that most coal-seams represent _ vegetable matter that has grown and has been entombed on the spot has never been received by all geologists with quite that measure of satisfaction that has been accorded to other theories of the same general nature. It has been felt again and again that the explanation referred to might be true enough for certain cases; but that in others it failed to account satisfactorily for all the pheno- mena. It involved too many complications—too nice an adjustment of the rate of growth of the vegetation to the rate of subsidence and of sedimentation—too much straining of the theory in question generally—to be accepted unhesitatingly by those accustomed to judge of such facts for themselves. That certain beds of coal have been formed by the growth of vegetation on the spot no reasonable person can doubt: the only question is whether that is true of every coal-seam. Many competent observers have thought it is not; and the number of those who are dissatisfied with the view set forth in most text-books is certainly on the increase. Mr. W. 8. Gresley, and several other geologists, have lately advanced good arguments in favour of other views, which many are disposed to accept as correct. J. G. Canc ereematian of Coail-seams. 309 Perhaps the truth in this case, as in many others, may be that similar results have been attained in a variety of ways, and that, instead of there having been but one mode of formation of coal- seams, there have probably been many. We might briefly consider some of these at this point. The formation of coal simply requires that a certain quantity of pure vegetable matter should be left at any given spot under conditions that insure its conversion before its chief constituents shall have passed into the inorganic condition. These results may be brought about in a variety of ways. Inland, for example, coal or its repre- sentative, lignite, may be formed through the burial of peat beneath the alluvium of lakes or of rivers. In marine areas it may arise through the sedimentation of inland peat whose constituents have been re-sorted and drifted out to sea. The submergence and sub- sequent burial of maritime beds of peat in sit may, under suitable conditions, give rise in another way to beds of coal. The entomb- ment of masses of drift-timber that have floated seawards must, again, largely contribute to the same result. Marine vegetation must occasionally play an important part in the formation of deposits of carbonaceous matter on the sea-bottom.’ Then there is the im- portant factor of the growth, decay, and entombment on the spot, of lagoon vegetation, originating in an area where deltas are subsiding intermittently, and with minor oscillations of level. Lastly, coal may be formed, as an ordinary sedimentary deposit, by the slow accumulation, in quiet water, of deciduous, or other, vegetable matter, floated seawards from riparian forests. Hach of these modes of formation of coal must have played important parts in the forma- tion of coal-seams, at every period of the earth’s history, from the dawn of vegetation down to the present day. The exclusive advocacy of any one mode is therefore as illogical as it is unnecessary. It seems to me that the last mode referred to has not received quite as much consideration as its importance deserves, and I propose there- fore, while attaching equal importance to the other modes, which are already well understood, to consider this particular one in some little detail. Before proceeding to do so it may be as well to review some of the facts connected with the mode of occurrence of coal- seams in general, with a view of arriving at a clearer idea of their various histories. It is now admitted on all hands that the principal constituents of nearly every coal-seam represent so much carbon that has at one time existed in the form of carbonic acid in the atmosphere, whence it has been extracted by the vital forces of growing vegetation. Subsequent pressure accompanied by certain chemical changes, well understood, have converted this fixed carbon into coal. The precise nature of the vegetable matter forming the coal varies within wide limits, not only on account of the varied ages, or the geographical position, of the seams themselves; but even within the coal-seams belonging to any one geological period and situated at the same part of the earth’s surface. There is, further, much diversity in the 1 I know of no evidence that marine vegetation (i.e. Aly) is capable of conversion into coal.—Epir. G.M. 310 J. G. Goodchild—Formation of Coal-seams. proportion that the different parts of the plants bear to each other in different seams. As a rule, tree trunks form but a small part of any coal-seam; and in the rare cases where they do so occur, they are not found in the position of growth, or extending upwards through the seam, but are prostrate, and lie parallel to the bounding surface of the coal. The coarser portions of the organic constituents of coals present a mixture, in variable proportions, of the more solid parts of the vegetation in a fragmentary state, together with portions of the cellular and the vascular tissues of the plants. Even such constituents as these are commonly in the minority. Fronds, leaves, and small stems occur rather more plentifully. But the greater part of the recognizable organic constituents of most coal-seams consist of a varied assortment of finely-divided vegetable tissue, together with spores, spore-cases, and bodies of that general nature. Some parts of nearly every coal-seam commonly fail to show any definite structure at all. The relative proportions of these varied constituents differ considerably in different coals; but the peculiar constitution of each coal-seam as a whole remains tolerably uniform over large areas. Not only do the constituents of each coal-seam as a whole differ from those of the seams associated with it, but the component layers of each seam differ amongst themselves. Every coal-seam is seen, on a very cursory examination, to be simply an aggregate of carbonaceous lamine, which are ordinarily thin, and are occasionally of almost microscopic proportions. A close examin- ation of these laminze shows that they differ each from the other to a much greater extent than a cursory examination would lead one to suppose. More than that. The structural characters of each of the lamina, whatever its thickness, remain constant to such an extent as to enable one to identify that particular lamina over a large area. Practical coal-miners are well aware of this fact, although they may not always be able to point to the precise nature of the distinction in each case. One lamina may contain nothing but spores and spore-cases ; a second next it, above or below, may consist of leafy matter alone; a third may be characterized by the constant presence of mineral charcoal, representing the vascular tissues of the old vegetation ; a fourth may be devoid of any evident traces of organic structure; or another lamina of the same coal-seam may contain, along with its organic constituents, a variable amount of impurities of organic origin. And yet, however, the several lamine may differ among themselves, they are found to retain their own special charac- teristics throughout the whole of a large coal-field. Hven where the coal happens to be changeable, as it often is near old irregularities of the floor upon which it lies, the rate of change is far from being rapid, except, of course, where the coal is splitting up through interlaminations or partings of inorganic matter. Some coal-seams pass into shales, by a progressive increase in argillaceous impurities; but they rarely, perhaps almost never, graduate into sandstones; although some irregular and lenticular deposits, which clearly represent drifted vegetation, may often do so. Coal not uncommonly graduates into carbonaceous clay ironstone. Jd. G. Goodchild—Formation of Coal-seams. - ‘3éll In rarer cases still the change can be traced through this last into impure limestone. Of this more presently. Sedimentary formations of nearly every geological period contain coal-seams in one part of the earth’s surface or another; and under every variety of geological or of geographical circumstances they present much the same features; and—allowance being made for the changes the containing rock may have undergone—their composition also is in nearly all cases practically constant. It would seem, therefore, that the formation of coal does not require any very exceptional conditions, such as an excess of carbonic acid in the atmosphere, or other abnormalities. There is often a curious (and significant) relation between the nature of the rocks associated with coal and that of the vegetable “matter entombed therein. In the Carboniferous series proper the sedimentary strata associated with the coals are usually shales; fireclays, and beds of sandstone of various degrees of coarseness also occur. In certain areas limestones and calcareo-siliceous beds (‘“‘cherts”) are also found. Vegetable. remains commonly occur dispersed throughout all of these, though the proportion varies much with the nature of the rock. It is in the coarse, drifted, material forming the sandstones, that tree trunks, if they occur at all, are most commonly found. And it is here that they are so often found embedded stem upward and root downward, reminding one so forcibly of the “snags” that are common in the sandy deposits of tropical rivers. (It should be noted, in passing, that the centre of gravity of most of the trees of the Carboniferous period must have lain close above the roots; so that in floating, they must have travelled root downwards, and as the decay of the soft interior proceeded, they must have tended invariably to sink to the bottom in nearly the position of growth.) The shales associated with coals rarely contain trees (I have not come across any proof that they ever do so); but fronds and leaves occur in plenty, and, more rarely, stems and small boughs may occur as well. ‘The fireclays (which are commonly regarded as old soils that have been exhausted of their alkalies and iron by the growth thereon of vegetation) often, but by no means invariably, contain roots—the well-known Stigmaria—in addition to the vegetable constituents found in the shales. Some sandstones show these Stigmaria roots as well, whether the rock is directly associated with coal or not. If limestones occur with the coals, these rarely contain traces of coal, except as lenticular masses, which are clearly due to the entombment of vegetable matter that has been drifted. A fine and well-known example of this kind is seen in the Mountain Limestone of Ingleton in North Yorkshire. A careful consideration of these facts relating to coal will make it clear that, whatever be its precise mode of origin in any given case, coal presents all the characters of a stratified deposit. It resembles most closely, in many of its characters, those strata that have slowly and quietly accumulated in nearly-still water. The resemblance to a stratified deposit is certainly not delusive and to be attributed to the effect of subsequent compression, because, as we have seen, the 312 J. G. Goodchild—Formation of Coal-seams. component laminz have each structural characters of their own, marking them off from those above and below, ou remaining con- stant over wide areas. Much stress has been laid upon the aaa association that is said to exist between seams of coal and beds of fireclay. But every practical mining engineer must be well aware of the fact that the two kinds of rock are by no means universally associated. Thick beds of fireclay occur in the Argill Coal-field near Kirkby Stephen, Westmorland,’ without a trace of coal near. One such bed is thirty feet in thickness. On the other hand, in certain rich coal-fields such a rock as fireclay (or as gannister) is conspicuous by its absence. Having glanced at an outline of the facts, we may pass on to consider one of the various modes of formation of coal—the others referred to are so obvious that no one can well have any doubt as to their validity in the present connection. As an illustration of what takes place, we may consider the sequence of events that must obtain in the case of any large river that is carrying seawards the spoils of a riparian forest region. Such a river transports vast quantities of inorganic materials; as well as more or less floating animal matter, which is partly terrestrial, partly fluviatile, partly estuarine ; there is, in addition, variable quantities of vegetable matter of all kinds— big tree trunks, boughs, stems, leaves, fronds, spores and spore- cases, and all the miscellaneous deciduous vegetable matter that may be derived from every part of the forest region above. The river does not transport its heterogeneous burden at a uniform rate of motion, nor does it drop it all at the same place. Far from that. The coarser mineral sediment drifts seawards along the bottom for a time, but finally comes to rest at no great distance from the land. Some of the tree trunks that have travelled so far as to become water-logged at this point sink here; and, obeying the laws of gravity, they sink with their heavier ends downward and are eventually buried root downward in the coarse sediment. Most of the animal matter, which decomposes quickly, also sinks near, and may be buried along with the trees. The finer inorganic matter drifts in suspension farther out to sea, where it subsides in crescentic zones on the seaward side of the coarser material, and entombs such of the vegetable matter as may have become water-logged at that part. Farther out to sea, or where the submarine currents have lost most of their transporting power, the finest sediment, after rolling about in clouds for a time, gradually subsides to the bottom, and there entombs also such of the vegetable matter whose constitution has enabled it to travel so far. Seaward of the zone where this happens quiet and still water prevails on the sea-bed. Here the littoral forms of marine life do not commonly reach ; and here also, it is commonly assumed that little or no organic matter transported from the land ever reaches. Most of the animal remains that may have floated down the river have probably all sunk, and been 1 <_< GroLtocicaL Society or Lonpon. I.—May 8, 1889.—W. T. Blanford, LL.D., F.R.S., President, in the Chair.—The following communications were read :— 1. “The Rocks of Alderney and the Casqueis.” By the Rev. Edwin Hill, M.A., F.G.S. The author in this paper described Alderney, Burhou, with its surrounding reefs, and the remoter cluster of the Casquets, all included within an area about 10 miles long. Alderney itself consists in most part of crystalline igneous rocks, hornblendic granites of varying constitution which resemble some Guernsey rocks, but seem more nearly connected with those of B02 Reports and Proceedings— Herm and fark. These are pierced by various dykes, and among them by an intrusion containing olivine, which may be placed with © the group of picrites. ‘There is also in the island a dyke of mica- trap. The eastern part only of Alderney, but the whole of Burhou, the Casquets and their neighbouring reefs, consist of stratified rocks. These contain rare beds of fine mudstone, but are generally false- bedded sandstones, and grits, sometimes with pebbles, often rather coarse and angular, occasionally becoming typical arkoses. At a point on the southern cliffs of Alderney they may be seen to rest on the crystalline igneous mass. - A series identical in constitution and aspect occurs at Omonville, on the mainland, a few miles east of Cap la Hague (as had also been noticed a few months earlier by M. Bigot). These have been correlated with others near Cherbourg, and described as underlying the “ grés Armoricain.” The Alderney erits therefore form part of a series which can be traced over 30 miles, and which belongs to the Upper Cambrian (of Lapworth). Remarks were made on the Jersey conglomerates (Ansted’s con- jectural identification of these with the Alderney grits being approved), on the resulting evidence that the Jersey rhyolites are not Permian, but Cambrian at the latest, on the still earlier age of the Guernsey syenites and diorites, and on the antiquity of the Guernsey gneisses. 2. “On the Ashprington Volcanic Series of South Devon.” By the late Arthur Champernowne, Esq., M.A., F.G.S. Communicated by Dr. A. Geikie, F.R.S., F.G.S. The author described the general characters of the volcanic rocks that occupy a considerable area of the country around Ashprington, near Totnes. They comprise tuffs and lavas, the latter being some- times amygdaloidal and sometimes flaggy and aphanitic. The aphanitic rocks approach in character the porphyritic “schalsteins” of Nassau. Some of the rocks are much altered; the felspars are blurred, as if changing to saussurite, like the felspars in the Lizard gabbros. In other cases greenish aphanitic rocks have, by the de- composition of magnetite or ilmenite, become raddled and earthy in appearance, so as to resemble tuffs. The beds are clearly inter- calated in the Devonian group of rocks, and the term Ashprington Series is applied to them by the author. Although this series probably oontains some detrital beds, there are no true grits in it. Stratigraphically the series appears to come between the Great Devon Limestone and the Cockington Beds, the evidence being discussed by the author, however, not so fully as he had intended, as the paper was not completed. II.—May 22, 1889.—W. T. Blanford, LL.D., F.R.S., President, in the Chair.—The following communications were read :— 1. “Notes on the Hornblende Schists and Banded Crystalline Rocks of the Lizard.” By Major-Gen. C. A. McMahon, F.G.S. The Lizard district has been visited by the author on three occasions during the years 1887-8-9, and the specimens of the Geological Society of London. 338 rocks collected were subjected to microscopic examination. After summarizing the work of previous writers, the author proceeded to consider the hornblende schists. He described these rocks and gave a table showing their constituent minerals. He noted the absence of quartz, the presence of pyroxene, and the fact that the minerals present are those commonly met with in volcanic rocks either as original minerals or as secondary products, and he considers that the microscopic study of the schists confirms the opinion of some previous writers that the schists had a volcanic origin and consisted principally of ash-beds. The absence of free quartz militates strongly against the supposition that they were originally sedi- mentary rocks of an ordinary character, whilst the fact of their being bedded shows that they are not plutonic. The author has _ found no evidence that the foliation of these rocks is due to dynamic deformation, and gives reasons for supposing that such was not the case. ‘The rock seems to have been originally homogeneous, and its banding produced at a later stage by the segregation of the horn- blende in planes parallel to the bedding. The rocks furnish abundant evidence of the action of water, as shown by the presence of calcite, chlorite, steatite, and other pro- ducts of aqueous action, as well as by channels fringed with magne- tite, ferrite, or limonite. The action of water in converting augite into hornblende may be distinctly traced when the slices still contain pyroxene. The production of periodical currents of water through the water-bearing strata adjoining the roots of a volcano was com- mented on, and the author suggested that the banding of the horn- blende schists was produced by such water leeching out unstable minerals, such as pyroxene, from the spaces between the planes of lamination, and the formation of comparatively stable minerals, such as hornblende, along those planes. The Lizard rocks contain good examples of the formation of hornblende in the wet way, that mineral having been deposited in cracks in such a way as to join together the ends of hornblende crystals severed by these cracks. The “granulitic” group, of which the author gave a table showing the constituent minerals, was then described. Judged by their mineralogical contents the dark bands consist of diorite and the white bands of granite. The author considers that portions of this group consist, like the hornblende schists, of converted ash-beds, but that other portions are composed of intrusive diorites of later date, the quasi-bedded appearance of both being due to the injection of granite. He pointed out that the quasi-banding is very irregular in its character, that the bands inosculate, bifurcate, aud entangle them- selves in complicated meshes inconsistent with the idea of regular banding, and that they are deflected by the blocks of serpentine imbedded in the dioritic portions of the granulitic rocks as well as by the porphyritic crystals of felspar contained in the latter. In certain places, as on the foreshore at Kennack Cove, the intrusive character of the granitic veins is undoubted, as they cut through the diorite in all directions, but they graduate into bands of normal 334 Reports and Proceedings—Geological Society of London. character. The author considers that the process of injection was aided by the plasticity of the “granulitic” beds induced by the neighbourhood of igneous masses; also in the case of sub-marine ash-beds by the planes of sedimentation ; and in the case of intruded sheets of diorite, by the foliation parallel to the bedding, the intrusion of the granite being subsequent to that of the diorite. At Pen Voose a foliated granite, the author pointed out, occurs in association with a non-foliated gabbro and diorite, a fact indicating in his opinion that the foliation of the granite was produced before its perfect consolidation. The granite was the last to appear in the order of time, and had the foliation of the granite been produced by pressure after cooling, the gabbro and diorite would also have been foliated. 2. “The Upper Jurassic Clays of Lincolnshire.” By Thomas Roberts, Esq., M.A., F.G.S. In Lincolnshire it has generally been considered that the Oxford and Kimeridge Clays come in direct sequence, and that the Corallian group of rocks is not represented. The author, however, endeavoured to show that there is between the Oxford and Kimeridge a zone of clay which is of Corallian age. Six paleontological zones were recognized in the Oxford Clay. The clays which come between the Oxford and Upper Kimeridge the author divided into the following zones :— (1) Black selenitiferous clays. (2) Dark clays crowded with Ostrea deltoidea. (3) Clays with Ammonites alternans; and (4) clays in which this fossil is absent. The black selenitiferous Clays (1) are regarded as Corallian, because (a) They come between the Oxford Clay and the basement bed of the Kimeridge. (b) Out of the 28 species of fossils collected from this zone 22 are Corallian. (c) Ostrea deltoidea and Gryphea dilatata occur together in these clays, and also in the Corallian, but in no other formation. The zones 2, 38, and 4 are of Lower Kimeridge Clay age. The lowest zone (2) is very persistent in character, and is met with in Yorkshire, Cambridgeshire, Oxfordshire, and the South of England. The remaining zones (8 and 4) are local in their development. 3. “Origin of Movements in the Harth’s Crust.” By James R. Kilroe, Esq. Communicated by A. B. Wynne, Esq., F.G.S. The author is convinced that a very important factor has been omitted from the usual explanation offered in accounting for the vast movements which have obtained in the earth’s crust. His acknowledgments are due to Mr. Fisher for the extensive use made of his valuable work. He also refers frequently to the views and publications of other writers on terrestrial physics. From a somewhat conflicting mass of figures he concludes that about 20 miles would remain to represent the amount of radial contraction due to cooling during the period from Archean to Recent times, corresponding to a circumferential contraction of 120 miles. This will have to be distributed over widely separate periods, at each of which there is abundant evidence of lateral compression. But be considers that this shrinkage alone will not account for Correspondence—Dr. C. Callaway. 300 al] the plication or distortion of strata which constitute so important a factor in mountain-making, and he is disposed to supplement it in the way to which allusion has already been made by Mr. Wynne in a recent Presidential Address, viz. by considering the effects of the attenuation of strata under superincumbent pressure from deposition in subsiding areas, which involves the thickening, puckering, redu- plication, and piling up of strata in regions where pressure has been lessened. It should be noted that, until disturbance of “cosmical equilibrium” takes place, mere pressure does not produce meta- morphism. The extent of these lateral movements is described, and it is asserted that the theories hitherto adopted to account for plica- tion, etc., are inadequate. The origin of the horizontal movements is further discussed on _the hypothesis that solids can flow after the manner of liquids, when they are subjected to sufficient pressure. He considers that the displacement in N.W. Scotland may have been initiated by the force due to contraction and accumulating in the crust throughout the periods marked by the deposition of Torridon Sandstone and Silurian stata, the elements of movement finding an exit at the ancient Silurian surface. In this case the pile of Silurian strata formerly covering the region now occupied by the North Sea and part of the Atlantic forced the lowest strata to move laterally, the protuberances of the underlying pre-Silurian rocks being also involved in the shearing process. Similar results occur in other mountain areas. The strata compressed have been greatly attenuated, and extended in proportion ; in this way we may account for the piling up of strata by contortion in certain regions. The connexion of this interpretation with Malet’s theory of volcanoes is also indicated, and the author concludes by applying these views to other branches of terrestrial physics. CORRESPONDENCE. ——_ FOLIATION IN THE MALVERN HILLS. Str,—I ask permission to make a brief explanation in reference to the debate on General Macmahon’s memoir read before the Geo- logical Society on May 22nd. The published summary of the dis- cussion attributes to Mr. J. J. H. Teall the statement that, in a paper read at a previous meeting, “foliation was actually taken as evidence of deformation.” The paper’ here referred to was one read by me on April 17th. Taken without qualification, Mr. Teall’s remark does not accurately express my views. Nothing is more certain than that foliation has been produced in more ways than one, and this I have repeatedly said and printed. In the Malvern Hills, however, I hold that foliation is always the result of deforma- tion. This conclusion is not assumed, but is based upon the fact that, wherever the rock lying between an igneous mass and a schist is exposed, a gradation. between the two can be traced, and the pro- 1 See summary of it in Gxonr. Mac. for June, p. 285. The discussion of papers, is omitted from the Reports given in the Macazine from want of space.— Epit. G. M. \ 336 _ Obituary—Mr, Robert Damon. gressive deformation can be shown under the microscope. I have a right to say ‘‘ wherever,” because I do not think there is a single exposure of any magnitude in the entire chain which I have failed to examine, and the most critical sections I have visited repeatedly. My paper of April 17th treated, not so much of the origin of the schists in question, as of the production of some of the constituent minerals. The evidence offered under the former head was accord- ingly very incomplete, and a great part of the debate seemed to me rather premature. I hope my critics will visit the Malvern region, and will favour me with their opinion when I read my paper on the main question. Cu. CaLLaway. WELLINGTON, June 11th, 1889. @rS sO Aee an ROBERT DAMON, F.G.S. Born, 1814; Diep, 1889, WE regret to record the death of Mr. Ropert Damon, F.G.S., of No. 4, Pulteney, Weymouth, Dorset, the well-known Geologist and Naturalist, which occurred suddenly from heart-disease, on Saturday the 4th May. He was the author of an excellent work on “The Geology of Weymouth, and the Isle of Portland,” and was a most extensive traveller and an assiduous collector. He procured a marvellous series of Cretaceous fossil Fishes from the Lebanon, Syria, now in the British Museum (Nat. Hist.), also the most com- plete example of the skeleton of that rare extinct Sirenian “ Steller’s Sea-cow,” from Behring Island. Although in his 75th year, he con- templated an expedition to Siberia in order to obtain an entire Mammoth’s skeleton for the National Museum. Mr. Damon fre- quently visited Moscow and St. Petersburg, and was a Corresponding Member of the Imperial Society of Natural History, Moscow, and of other learned bodies in various parts of the world. Only a few years since he took passage from Nijni Novgorod down the Volga to Astrakhan, where he made the first collection of the fishes of the Caspian Sea yet brought to this country. He lately purchased the celebrated collections forming the “Museum Godeffroy” in Hamburg, together with the published catalogues of that museum prepared by various eminent naturalists. In his native town of Weymouth, Mr. Damon exercised great influence for good amongst his fellow-townsmen, by whom he was greatly honoured and valued for the integrity and uprightness of his character, and his large-hearted sympathy with all cases of distress. His charities were performed without ostentation, and only the recipients ever knew the kind friend who helped them in their time of need. His loss will long be felt by a very wide circle of friends, in all parts of the world, by whom he was warmly esteemed and greatly respected. His son, Mr. R. F. Damon, now carries on his father’s extensive Natural History Agency in Weymouth. Henry Wiiiram Bristow, F.R.S., F.G.S., late Director of the Geological Survey of England.—We have to announce the death ori the 14th of June, of this eminent geologist, at the age of 72. Mr. Bristow had for some time past been an invalid, We hope to publish a notice of his scientific labours in the August number, Geol. Mag mtsfatos met Decade IILVol.VLPl Be _ Pe. ; TULA, SLZE A.S. Foord del. et lith. West Newman imp. lias Marlstone Rock and Transition Bed Fossils. Tultor, Leicestershare THE GEOLOGICAL MAGAZINE. NEW SERIES. DECADE Ill. VOL. VI. No. VIII.—AUGUST, 1889. ORIGINAL ARTICLIEHS. AUN Ee St I.—Tue Lias Martusrone or Titron, LeicestersHIRe. By E. Wizson, F.G.S., and W. D. Cricx, With Paleontological Notes by E. Wiuson, F.G.S. (PLATE X.) (Concluded from the July Number, p. 305.) Carpinia Sutatteri1, Walford, 1878. Plate X. Figs. 1, 2. 1878. Isocardia? Slatteri, Walford, ‘‘On some Middle and Upper Lias Beds in the Neighbourhood of Banbury,’’ Proce. Warwick Nat. and Arch. Field Club, 1878, p. 49. 1879. Jsocardia, sp. in reprint of same paper, pp. 16, 20, fig. 5 in plate. Description.—Shell trigonal, thick ; umbones large, angulated and terminal, ending in acute points, which curve downwards, forwards, and a little outwards; the sides of the shell, triangular in form, slightly excavated and highly inclined to the areas, are bounded by prominent carinz, an acute carina separating the side from the slightly concave triangular area in front, and a more rounded carina separating it from the slightly convex triangular area behind. The valves are marked with strongly defined and somewhat sinuous sub- imbricating lines of growth at wide and fairly regular intervals, between which may be discerned numerous fine lines of growth. Lunule small and deep. Cardinal tooth elongated, oblique and pro- minent in the right valve, small and triangular in the left. Anterior lateral tooth of right valve obtusely conical and very prominent, received into a deep socket in the corresponding valve, immediately above the impression of the anterior adductor muscle; posterior lateral tooth in left valve elongated, longitudinally grooved and attenuated towards the umbo; muscular impressions deeply sunk into the substance of the shell, the anterior triangularly ovate, the posterior oval-oblong; pallial line not discernible in specimens examined ; ligament external, groove for its insertion elongated, shallow and curved concentrically with the dorsal margin of the shell. Height of shell, 18 to 25 mm.; breadth, 21 to 29 mm. Note.—This shell has somewhat the form of an Opis, and is very like Opis Ferryi, Dumortier (Dépdts Jurassiques, pt. 3, p. 264, pl. xxx. fs. 4-6) ; but it differs from that shell by its more strongly curved outlines, absence of longitudinal ribs, and larger size. Possibly that form, as well as certain other trigonal bicarinated shells having imbricating growth layers—and the hinge characters DECADE III.—VOL. VI.—NO. VIII. 22 338 MY. Wilson and Crick—The Lias Maristone of Tilton. of which have not been noticed—may eventually be found to fall under the genus Cardinia. This fossil was first discovered by Mr. HE. A. Walford, F.G.S., in the Marlstone and Middle Lias Transition-bed of Aston-le-Wall and Appletree, Northamptonshire, and referred to in this author’s paper above cited, and figured but not described in the reprint of same, under the name Isocardia Slattert, Walford. At that time the hinge characters had not been made out, and consequently the generic identification was made with some diffidence. Mr. Crick has since found an almost perfect left valve of this shell on the Hast Norton embankment, and Mr. Walford has kindly lent me a right valve, in which also, now that the matrix has been cleaned out, the hinge characters are clearly displayed (see Pl. X. Fig. 2). These hinge characters are essentially those of a Cardinia, as also is the mode of growth, and to that genus I therefore without hesitation refer this shell, and in this view Mr. Walford concurs. Marlstone Rock, Tilton (Hast Norton embankment). Pinna TriLTonensis, sp. nov. Plate X. Fig. 3. Shell elongated, lanceolate, anterior and posterior borders with nearly straight edges, but slightly convex ; with concentric longitu- dinal plice, which towards the umbo become broken up and mamuillated; the posterior half of each valve is ornamented with slender radial coste, which are regular and equally spaced except the two lower or median ones, which are more slender and wider apart; about half only of the radial costee reach the ventral border of the shell; these radial striz, where they cross the plice of growth, form a neat meshwork, and are as a series interrupted at intervals, where they take an oblique direction for a short distance so as to present a distorted appearance. We have two examples of this shell; both are incomplete, and the best-preserved specimen which is figured is very much compressed ; hence the materials for founding a species are not the most satisfactory, and the above name must be considered therefore as provisional. Marlstone Rock, Tilton (Hast Norton embankment). INOcERAMUS, sp. Plate X. Figs. 4, 4a. Shell markedly inequivalve, moderately inflated, longer than broad, broadly flattened posteriorly in the left valve, acuminated towards the umbones, which are prominent, pointed, approaching and recurved ; the valves are marked with irregular longitudinal ridges and furrows, and finer concentric lines of growth, and by rather ill- defined and irregular radial striz, which at their intersections give an irregularly mammillated and pitted aspect to portions of the shell. This shell differs in its form and markings from all the Jurassic Tnocerami with which I am acquainted; but having only a single and incomplete specimen, I hesitate to impose a new name. Should it eventually appear that we have here a new species, the name Inoceramus Tiltonensis might be given to it. Marlstone Rock, Tilton (Kast Norton embankment). \ UMM. Wilson and Crick—The Des Maristone of Tilton. 3839 HoDIADEMA GRANULATA. The beautiful specimens of this Middle Lias Echinoid belong to a new genus, the description of which will be found in “A Revision of the Genera (Fossil and Recent) of the Hchinoidea,” Journ. Linn. Soc. vol. xxiii. 1889, by Prof. P. Martin Duncan, F.R.S., etc. The following is the diagnosis. Genus Hodiadema, Dunc. 1889. Test small, thin, circular in tumid marginal outline, sub-conical dorsally, tumid and reentering actinally, broader than high. Apical system moderate in size, ovoid or elliptical in outline at the peri- proct: five large basal plates, four in contact, but the fifth or posterior separated from the others on either side by radial plates, which thus enter the ring. Ambulacra narrow, straight, wider than the inter- radia at the peristomial margin, narrower elsewhere; poriferous zones narrow, pairs of pores numerous, in single, simple, vertical series, barely any crowding near the peristome; plates all low broad primaries; interporiferous areas rather broad, crowded with blunt granules dorsally, some larger granules near the poriferous zones, and giving place at the ambitus to some very small crenulate perforated tubercles, which diminish actinally. Interradia broad, plates not numerous, broader than high; two vertical rows of per- forate, crenulate and scrobiculate tubercles in each area, a few large at the ambitus, and all becoming rapidly small and almost obsolete dorsally, or replaced there by granulation, diminishing also actinally. Scrobicules of the ambital tubercles large, usually coalescing. A large blunt granulation occurs beyond the scrobicular circles, except on angular median spaces contiguous with the basal plates where there are no granules. Peristome decagonal, sunken, small, with well-marked branchial incisions. The position of this genus is in the family Diadematide and in the sub-family Orthopsine. HopIADEMA GRANULATA, sp. nov. Plate X. Figs. 5, 5a, 5b, 5c. Test small, sub-conical above the tumid ambitus, circular in ambital outline. Apical system with granulated basal plates, with large perforations ; the posterior radial plates large, separating the fifth basal plate and entering the periprocteal ring ; the others smaller, triangular and excluded. A raised rim around the periproct. Poriferous zones somewhat sunken; all plates simple primaries ; tubercles very small in two vertical rows. Dorsal surface of interradia, except in the median lines down to varying distances towards the ambitus, very boldly granulate; in the triangular spaces, from the basal plates along the median lines there is but slight granulation or it may be absent. About five large primary tubercles in each inter- radium at the ambitus, perforate, crenulate, and with coalescing scrobicules. Peristome reentering; with branchial incisions limited by raised lines. Height, 6mm.; breadth, 12mm. Marlstone Rock, Tilton (Hast Norton embankment). 1 The otherwise faithful drawing, Fig. 5a, should have fewer granules upon the interradial plates close to the basal plates. 3840 MM. Wilson & Crick—The Lias Marlstone of Tilton. OnyouiTzs, sp. Plate X. Fig. 6. Two of the peculiar bodies known by this name were obtained by Mr. B. Thompson, F.G.8., from the East Norton-embankment. The specimen here figured may be described as follows: Cylin- drical curved hollow body tapering to a point at each end, somewhat constricted in the middle (8 mm. in diameter) and expanded towards the ends (4 to 5 mm. in diameter), and flattened and with acute edges towards one end; this body is bow-shaped, the points curving towards the same side, but in planes considerably inclined to each other ; the pointed ends are about 4:5 centimetres apart; the shelly covering is thin, smooth and apparently structureless, but under a high-power lens its external surface appears to be finely punctated; the shell is separated from the surrounding matrix by a uniformly narrow hollow space about -5 mm. broad, indicating apparently the former presence of a soft investing organic layer, which has disappeared in the process of fossilization. At first sight these hollow cylindrical bodies look as if they might have belonged to tubicolar Annelids; but it is to be observed that their tubes are closed at both ends, ane that, as we have just seen, there are indica- tions of their having been internal and not external structures. Thirty years ago, Quenstedt described several of these curious bodies in “Der Jura.”! At one time it appears they were taken for ‘compressed crabs-claws”’! Dr. Fraas considered them to be the acetabular hooks of Cephalopods, referring them to Onychoteuthis, and. in this view Quenstedt concurred. Messrs. Tate and Blake state in ‘The Yorkshire Lias’*? that they met with these pointed organisms in the ‘Jamesoni beds’ at Peak, agreeing with the Onychites numismalis, of Quenstedt, but they avoided any speculation as to their true nature. I am inclined to accept the explanation suggested by Fraas and Quenstedt. Marlstone Rock, Tilton (Hast Norton embankment). EXPLANATION OF PLATE X. Fic. 1. Cardinia Slatteri, Walford. Marlstone Rock, Tilton (East Norton embankment). Left valve, exterior. Nat. size. a Nes Ibid. Marlstone Rock, Transition-bed, Appletree. Right valve, interior. Nat. size. sot kos Pinna Tiltonensis, sp. nov. Marlstone Rock, Tilton (East Norton em- bankment). Nat. size. 5» 4, 4a. Inoceramus, sp. Marlstone Rock, Tilton (Hast Norton embankment). Right and left valves. Half nat. size. », 5. Hodiadema granulata, sp. nov. Marlstone Rock, ‘Tilton (East Norton embankment). Side view, enlarged twice. OL Tbid. Apical system. Same locality. “Enlarged six times. 59, OO Ibid. Mouth opening. From another specimen, enlarged three times. ap BS Ibid. Ambulacrum and interambulacrum, enlarged six times. Os Onychites, sp. Marlstone Rock, Tilton (East Norton embankment). 1 « Der Jura,” p. 201, pl. 24, fs. 59-62, and pp. 246-7, pl. 34, fs. 2-6. 2 «© The Yorkshire Lias,’’ p. 448. ~ MM, Wilson & Crick—The Lias Maristone of Tilton. 34] APPENDIX. List oF Fosstus From THE LiaAs Maristone (including the ‘‘ Transition Bed’’) of Tilton, Leicestershire. REPTILIA. | Lchthyosaurus, sp. vertebree. CEPHALOPODA. Amaltheus margaritatus, De Montf. », spinatus, Brug. flarpoceras acutum, Tate. >, oQvatum, Young and Bird. », serpentinum, Rein. Stephanoceras annulatum, Sow. >, commune, Sow. >» semicelatum, Simpson. Lelemnites apicicurvatus, Blainv. » oreviformis, Voltz. », Clavellatus, Bean. », paxillosus, Schloth. Nautilus truncatus, Sow. GASTEROPODA. Acteonina fragilis, Dunker. >, Jerrea, Wilson. », Llminsterensis, Moore. 5, Simemurzensis, Martin. Amberleya( Trochus) Gaudryana, d’Orb. ” 29 ”? a var. Cerithium confusum, Tate. », costulatum ? Des). », Jerreum, Tate. , Llminsterensis ? Moore. >, “4assicum, Moore. », veliculatum ? Desi. Chemnitzia (2?) Periniana, d’Orb. s », (?) (Lurritella\ undulata, Benz. Cryptoenta expansa, Sow. ,, votelleformis, Dunker. >, solarioides, Sow. Cylindrites egualis, Wilson. Monodonta bullata, Moore. Pseudomelania (Chemnitzia) Branno- viensis, Dumort. » (Phasianella) turbinata, Stol. 99 Sp. Pleurotomaria (Turbo) canalis, Mi. », (Zvrochus) helicinoides, Roemer. 5, vustica, Desl. », similis (=anglica), Sow. Trochus ariel, Dumort. », Lidia, d’Orb. », 4neatus, Moore. », Lethertonensis, Moore. », votulus, Stol. Turbo cyclostoma, Benz. », rugifera, Moore= T. coronatus, Moore = /Y. costulatum, Moore. », latilabrus, Stol. LAMELLIBRANCHIATA, Anomia numismalis, Quenst. Astarte striato-sulcata, Roemer. Cardinia concinna, Sow. », (Lsocardia) Slatteri, Walford. Ceromya bombax, Quenst. Goniomya heteropleura, Ag. Gresslya intermedia, Simpson. 5, lunulata, Tate. fiinnites abjectus, Phillips. », wvelatus, Minster. Lnoceramus, sp. Lima eucharis, d’Orb. », Hermannt, Voltz. », pectinoides, Sow. Limea acuticosta, Munster. », juliana, Dumort. Macrodon Buckmanni, Buckm. Modiola numismalis, Oppel. 5, ornata, Moore. », scalprum, Sow. Monotis ineguivaleis, Sow, Ostrea (Gryphea) cymbium, var. depressa, Lam. » submargaritacea, Brauns. Pecten acutiradiatus, Goldfuss. », @eguvalvis, Sow. », calvus, Goldfuss. », dentatus, Sow. », lunularis, Romer. », priscus, Schloth. », textorius, Schloth. Pinna Tiltonensis, n.sp. Piicatula spinosa, Sow. Protocardium truncatum, Sow. Tellina gracilis, Dumott. Unicardium subglobosum, Tate. BRACHIOPODA. Discina reflexa, Sow. Rhynchonella acuta, Sow. var. bidens, Phill. >, Amalthec, Quenst. », Jodinals, Tate. », cetrahedra, Sow. Be », var. LVorthamptonensis, Walker. Spiriferina rostrata, Schloth. Lerebratula punctata, Sow. a5 », var. Hdwardsit, Dav. 58 », var. Havesfieldensis, av. », Punctata, var. Radstockensis, Dav. », Walford, Dav. Waldheimia indentata, Sow. », mumismalis, Lam. », vesupinata, Sow. >, sub-numismalis, Dav. 342 I. C. Russell—Subaérial Deposits of North America. BRYOZOA. Diastopora oolitica, Vine. 99 stomatoporoides ? Vine. ECHINODERMATA. Lodiadema granulata, n.sp. Pentacrinus levis, Miller. ANNELIDA. Ditrupa capitata, Phil. », etalenszs, Piette. », guinguesulcata, Munster. Serpula tetragona, Desl. », ¢ricristata, Goldfuss. ACTINOZOA. Thecocyathus, sp. INCERTA SEDIS. Onychites, sp. II.—SusabriaL Deposits or tHe Arip ReGion or Nort AMERICA. By Isrart C. Russext, of the United States Geological Survey; Washington D.C., U.S.A. Part II. (Concluded from p. 295.) COMPARISON of adobe with the loess of China forms the con- cluding part of this paper; but as no analyses of the Chinese deposit are known to me, a few analyses of the loess of the Missis- sippi Valley are inserted, not with the assumption, however, that the deposits bearing the same name in these two regions are identical. A comparison of this table with the one showing the composition of adobe is instructive, as it indicates that these two yellow earths have a very similar composition. There are other respects in which they bear a close resemblance to each other; but as my acquaintance with the loess of the Mississippi Valley is limited, this comparison will not be carried further. ANALYSES OF THE Logss oF THE MisstssiPpPI VALLEY.! Constituents. No. 1. No. 2 No. 3. No. 4. SOs er ereeern ss TOEOS > ocaose Gele@l — oscoae (ASA Gee 60°69 INO Ey Ghee aaceanes NPROR! Badoso VOKG4. 1 Seo. LQs26) waeeeen 7:95 1RG AO) dccosnddeses SHS. 9 saoade DG so séo0se BPD Ssonoc 2°61 He Or neaye ence 0 Gen eine Oye eee TD) «sce 67 AMO sy escbacee ness Sito Meee oe 2A 0) arsRivece SP4AA yh eeee 52 Te) Gacaaenenen SD Ome eke: ANB - sadsac OO" a hsass 13 Mn Ops Se: “06 “(Sane ODM ee “12 CaO) 2a roe. SOURS ee GH Sb oace 156 9 Bae ans 8:96 MgO SOONERS ESR Bit Seite ent ane OLOO lem eecae 1 ae a 4°56 INiais OMe eaten ISG BN set ek ICSU Mecca 4 Si oases 1:17 TEGO se ee Wa eek B22 1,33). bea 2°06" ees I SBiaee ee 1-08 TOM ca eee BLOOM ee See 220 Olas PIO see 80 al-14 CODER ea OBO) i aA Gustine RS se a 9-63 SO Rw) eeeiee ate OE} A a STA menses (0X9 Soosen 12 Cyaacteeee CON aa anar SOM peaeeee “Lon meeee “19 100-21 99-99 99°78 99-54 a Contains H of organic matter, dried at 100° C. Organic Remains.—The fossils occurring in adobe, so far as I have been able to ascertain, are confined almost entirely to two classes, namely, land-shells and the bones of land-animals. Freshwater- ' From “The Driftless Area of the Upper Mississippi Valley,’? by T. C. Cham- berlin and R. D. Salisbury, Sixth Ann. Rep. U.S. Geol. Surv. 1884-1885, p. 282. I. C. Russell—Subaérial Deposits of North America. 348 shells are frequently present, but their number, so far as observed, is always small in comparison with the associated land-shells. Samples of adobe collected near Fort Wingate, N.M., contained the following fossils, as has been kindly determined for me by William H. Dall, who states that they all belong to living species and occur from Alaska to Mexico. Lanp-SHELLS. FRESHWATER- SHELLS. Succinea salleana ?, Pfr. Bythinella tenwipes, Couper. Hyalina (Conulus) chersina, Say. Limnea desidosa? sei Hyalina conspecta, Bland. Pisidium virginicum ? Bourg. Hyalina arborea, Say. Planorbis ae Say. Pupilla fallax, Say. Anodonta? (in small fragments). Vertigo ovata, Say. CRUSTACEAN CASES. Pupa muscorum, Linn. Cypris. Near Caiion City, Col., I saw detached bones, apparently of the Bison, which were obtained at a depth of twenty feet in adobe. Other similar finds are reported in the same region, but the bones obtained have not been preserved. In one instance, near the same locality, a tooth of an Elephant was obtained at a depth of forty feet in the adobe deposit. These bones are always detached, and are true fossils belonging to the deposit in which they occur. The only marine shells found in the adobe are fossils that have been derived from older rocks. An instance of this came under my notice near Caiion City, where fragments of an Inoceramus were found in this deposit, which could be readily traced to Cretaceous outcrops near at hand. These fossils should be considered merely as pebbles so far as they relate to the character and origin of the adobe. Mode of Formation.—That adobe is a subaérial deposit derived from the waste of surrounding mountain slopes, does not seem open to question. Its accumulation is now in process and may be studied in all its details at thousands of localities; the most instructive being the drainless and lakeless valleys of Utah, Nevada and neigh- bouring areas. The action of ephemeral streams and of the general surface wash in transporting debris from the uplands to the valleys may be observed in such basins at any time when rain falls. The thousands of little streams and rills, born in the hills of the Arid Region from the waters of passing showers, flow rapidly down the steep slopes, loaded with coarse sediment and turbid with fine yellow silt. On leaving the mouths of the rocky gorges, and entering one or more of the channels that lead from them down the alluvial slopes, the coarse material is deposited, and when the showers are transient, the water disappears by evaporation and by percolation through the material of the alluvial cones. During this process fine silt is deposited in the interspaces of the alluvial cones, and serves to make them more and more impervious. When the rain is copious, the streams may continue to the plain where the waters spread out in’ sheets among the desert shrubs, and deposit their silt. The particles of silt deposited by the ephemeral streams absorb the precipitates which are thrown down when the evaporation of 3844 =I. C. Russell—Subaérial Deposits of North America. the water that transported them takes place. During the long hot summers the water absorbed by the material filling enclosed basins’ is drawn to the surface by capillary attraction and evaporated. In this manner additional mineral matter is precipitated among the sedimentary deposits. It is evident, therefore, that the fine yellow earths filling enclosed basins owe their accumulation to both mechanical transportation and chemical precipitation. It may be suggested in this connection that the coherency of adobe, which enables it to stand in vertical escarpments for a long series of years, may be due to the partial cementation of its particles by the precipitation of mineral matter, principally calcium carbonate, among them. An examination of the fine silt in alluvial cones shows that it is identical with the silt forming the plains in the lower portions of the valleys in which they occur, except that it is not so evenly assorted, and in general is coarser. In both situations it is usually light yellow in colour, seemingly without reference to the character of the rocks from which it was derived. In addition to the material swept into the enclosed basins by ephemeral streams, there is another source of supply through aérial transportation. Dust is blown from the mountains overlooking the areas of accumulation and from neighbouring valleys, but the amount thus contributed is very small in comparison with the vast quantities of both coarse and fine material transported by water in the manner described above. This subject is again referred to on page 349. The fine dust blown into the air by volcanoes has also con- tributed to the filling of the valleys of the Arid Region. The total quantity of fine particles thus deposited must be very great, but it has only been observed near recent volcanoes in the neighbourhood of Mono Lake, Cal., and in Southern Utah. Interstratified with lacustrine sediments in the basin of Lake Lahontan’ there are deposits of white volcanic dust aggregating a thickness of perhaps six or eight feet, which was derived from the Mono craters two hundred miles away. ‘This indicates that very many of the drain- less valleys of Nevada and California must have received important contributions from the same source. Relation of Adobe to Playa Deposits——When an inclosed basin receives sufficient precipitation to form a lake, a portion of the fine debris swept down from neighbouring hills will be carried into it and deposited. In the Arid Region transient water bodies of this nature termed playa lakes are formed during every storm. These lakes are of all sizes up to hundreds of square miles in area, but are always extremely shallow, a depth of more than a few inches being rare. They usually disappear as quickly as they came, when the storms which supplied them pass away. On evaporating they leave a smooth plain or playa of light yellow mud, which is of almost impalpable fineness, and shows only very obscure, if any, lines of stratification. The last statement is based on a number of excavations which have been made in such deposits to a depth of six or eight 1 Monograph No. 11, U.S. Geol. Sury., 1885, p. 146. I. C. Russell—Subaérial Deposits of North America. . 345 feet; but, as natural sections are wanting, the thickness of these deposits as well as their internal structure is not well known. The lack of stratification in playa deposits may perhaps be due to the peculiar conditions under which they accumulate. The material composing them is fine throughout, but the waters continue turbid so long as they remain unevaporated, and the last addition made to the filling of the basin, in part a chemical precipitate, is of exceed- ing fineness. When the basins are refilled, this mud is quickly saturated, and may be again taken in suspension and in part redis- solved. ‘The deposits of various rainy periods may in this way be mingled so intimately that no lines of stratification would appear. Playa lakes are sometimes alkaline and saline, and on evaporating deposit salts of various kinds. Commonly, however, especially in the smaller basins, no salt appears at the surface, but the playas present a smooth, even expanse of cream-coloured mud, which becomes hard and divided into a net-work of shrinkage cracks when it dries. The fine sediment carried down the sides of an inclosed basin holding a playa lake is deposited in part before reaching the lake, and in part, as we have seen, in the lake itself. In both instances the accumulation is a yellow, finely divided earth, practically with- out stratification. In both instances the fine silt may have worn or angular pebbles and stones mingled with it, but in large valleys the accumulations, whether subaérial or subaqueous, are entirely of homogeneous yellow earth. The only marked difference in these - deposits is that the playa are much more saline than the subaérial earths. The sediments of playa lakes are sometimes obscurely vesicular, as if small gas bubbles had been formed in them. In subaérial deposits this has not been observed. The subaérial deposits, on the other hand, are traversed, at least in a number of instances, by small vertical tubes that branch downward; in the playa deposits these are not present. Relation to Stream Deposits.—Wherever the streams of the Arid Region overflow during high water and submerge their flood plains, a fine deposit is thrown down which in many instances is to all appearance identical with the adobe formed in drainless valleys. The deposit made by a stream in its immediate channel, at least in the vicinity of mountains, is coarse, and is frequently composed of well-worn boulders and gravel. As the stream sways from side to side of its general course during a succession of years, a sheet of gravel is spread out as a flooring over an entire valley. The material deposited on the flood-plain however, and superimposed on the gravelly stream-bed previously laid down, is usually a fine silt, which in many instances does not show lines of stratification. Along the streams of the Arid Region the flood plain deposits are frequently composed of fine, grey adobe, which breaks in vertical walls when undermined, and is without stratification. In some instances it is penetrated by vertical tubes apparently made by rootlets. In all these characteristics the stream deposit agrees with the subaérial deposit. 3846 86. OC. Russell— Subaérial Deposits of North America. That the flood-plain deposits of an arid country should be of the same character as the adobe deposited on gentle slopes and in inclosed valleys by ephemeral streams, is not surprising, since the process in each instance is essentially the same and the material handled is identical. The ephemeral streams spread out their waters on reaching gentle slopes, and deposit their sediment quietly among the scanty desert vegetation. In the case of perennial streams which overflow their banks the process is similar, that is, they form sheets of comparatively still water along their borders, and deposit silt about the vegetation which obstructs their flow. In both instances it is to be expected that casts of the roots of plants would remain in the soil. Evaporation takes place in both instances, thus contributing precipitated mineral matter to the deposits, but occurs most rapidly in the case of the ephemeral streams. In flood-plain deposits the shells of the freshwater molluscs occur, while land-shells may or may not be present. In the deposits of ephemeral streams the shells of land molluscs predominate, not to the exclusion of freshwater-shells, however, since the deposits are laid down by streams which in their upper course may survive throughout the summer and be inhabited by molluscs. The bones of land-mammals may be buried during either mode of accumulation. The geological interest of adobe and allied deposits centres not only in the manner in which they are formed, but also in their extent and depth when accumulated under favourable conditions. It is evident that the subaérial filling of an inclosed basin with fine material might continue in the manner described, until the depression was filled or the source of supply exhausted, so long as the climate conditions remain favourable. A decrease in precipitation would retard the filling or perhaps check it altogether, while an increase would favour the extension of playa lakes, or transform them into permanent water bodies. Should the increase be sufficient, the per- manent lakes would overflow and cut down their channels of dis- charge until their basins were drained to the bottom. It appears, therefore, that the maximum thickness which subaérial deposits may attain in an arid region is very great, especially in the case of fault valleys, which may have their borders raised at the same time that their bottoms are being filled. The thickness which playa lake deposits may attain is also very great; for, like the subaérial deposits just considered, they depend for their accumulation, the supply continuing, on a combination of climatic and topographic conditions which may remain favourable for a long period of time. Of the three methods described above, by which fine silt deposits may be accumulated in arid regions, the least important in a geological point of view is the one dependent on the overflow of streams. In the formation of flood-plains the conditions favouring accumulation depend not only on climatic and topographic con- ditions, but more definitely than in the other instances on the supply of suitable material The supply of sediment not only determines whether a stream shall deposit or not, but whether the I. O. Russell—Subaérial Deposits of North America. 347 deposits once laid down shall remain. In the formation of adobe and playa deposits, however, there is substantially no waste. While adobe and playa deposits depend on aridity of climate for their formation, the flood-plain deposits are not so limited, but may go on apparently with the same results in an arid as in a humid climate, provided a periodic variation in the volume of the streams takes place, sufficient to cause them to overflow their banks during the flood stage. There seems to be no reason to suppose that the character of flood-plain deposits in arid and in humid regions should be distinct, unless it be that the fine material washed into streams in dry countries is largely supplied from subaérial deposits which have already been assorted, and perhaps have a different chemical character from the surface debris of humid regions. It is beyond the scope of the present paper to discuss the processes by which flood-plain deposits are formed, especially as accumulations of this character are comparatively inconspicuous in the Arid Region, and also because the constructive power of streams has been exten- sively studied elsewhere. The accumulation of adobe and of eolian and volcanic dust in the central portions of the valleys of the Arid Region, together with the formation of talus slopes and alluvial cones about their borders, promotes the levelling of the hills and the filling of the intervening depressions. The tendency of this twofold process is to reduce the country to a plain, but not to bring it to sea-level. An exception here exists to the nearly universal law of base-level erosion, an exception, however, that is transient when considered in the way that geologists are forced to reckon time. A long continuation of existing climatic conditions, together with an absence of orographic movements, in the Great Basin portion of the Arid Region, would result in the formation of a broad high-level plain with rocky crests projecting here and there to mark the sites of buried mountain- ranges. A change to more humid conditions after this process was far advanced would initiate drainage systems which would make rapid changes in the configuration of the region. One of the first results of an increased rainfall would be the cutting of deep canons, especially in the unconsolidated adobe and playa deposits, thus exhibiting sections of these peculiar formations and revealing their great thickness. In connection with a description of the occurrence of adobe it is proper to state that nothing similar to the red soils formed by the residual clays of the South Atlantic States, or the red earth of Bermuda and the West Indies, or the terra rossa of Southern Hurope, or the laterite of India, is to be seen anywhere in the Arid Region. Rock disintegration is there active, but rock decomposition is retarded. The absence of residual clays from the comparatively rainless portion of this country is of interest as tending to show that such deposits are formed in humid and not in arid countries." 1 The subaérial deposits of humid regions have been discussed at some length by the present writer in Bulletin No. 52 of the U.S. Geological Survey (1889), to which this paper may be considered as a supplement. 048 =I. C. Russell—Subaérial Deposits of North America. IJ.—Comparison OF THE ADOBE WITH THE LOESS OF CHINA. It is of interest to compare the adobe of the Arid Region wit similar accumulations elsewhere, and especially with the loess of China, which has been very fully described by F. Von Richthofen.! In China there are many basins comparable with those in the more arid portion of the United States, which are deeply filled with a yellow marly-clay of impalpable fineness termed Loess, which is without stratification, breaks most readily in a vertical direction, and stands in perpendicular escarpments for many years. It is traversed by vertical tubes of small dimensions which bifurcate downward; is charged with land-shells, and contains the bones of land-mammals. In all of these particulars the loess of China agrees with the adobe of the Arid Region. The loess is described as being uniformly yellow in colour, and, as we have previously stated, this is the characteristic colour of the vast subaérial deposit of the Arid Region, except when charged with organic matter. In China certain peculiar concretions occur in the loess, figures of which are given by Richthofen ;? these, so far as known, are not represented in the adobe. A portion of the loess of China, termed “lake loess,” has been described as being a stratified deposit formed in saline lakes. These beds are practically identical with the playa deposits of the Arid Region, except that a more marked stratification has been observed in them. In each country these deposits are composed of fine, light yellow earth, more or less saline, and sometimes carry salts of various kinds in sufficient quantities to be of commercial value. The loess of China has been shown by Richthofen to have a thickness of fully 2000-2500 feet. There is a lack of accurate data by which to determine the thickness of the similar deposits in America, but observations based on the contours of valleys and on the records of the few wells that have been bored, indicate, as already stated, that in many instances it is fully as thick as the loess. In China the peculiar property of the loess, which admits of its standing in vertical escarpments, is utilized by the inhabitants, who excavate houses in the faces of the bluffs. In America the same property in the adobe admits of the formation of sun-dried bricks, which have been used in the construction of thousands of houses, and in many instances of entire towns. In each country the deposits mentioned form exceedingly rich agricultural lands. The loess is described as being porous, so that rain falling on it is rapidly absorbed. This property is shared in part by the adobe, but is not a characteristic feature of the deposit in general. On the alluvial cones and in the higher portions of the adobe-filled basins of the Arid Region, the rain-water rapidly disappears by percolation, but in other instances, and especially in the playas, the earth is extremely impervious. Only a foot or two beneath the playa lakes 1 China, Berlin, 1877, vol. i. pp. 56-189. See also abstract in Am. Jour. Sci. 8rd series, 1877, vol. xiv. pp. 487-491. * China, vol. i. p. 58. I. 0. Russeli—Subaérial Deposits of North America. 349 the yellow earth is always dry and powdery. These lakes are frequently called “sinks,” as the “sink of the Carson River” for example; but a more complete misnomer could scarcely be cited, as the water escapes from them solely by evaporation. There is one remarkable peculiarity in which the loess region of China differs from the Arid Region, that is, it has been deeply dissected by stream erosion, so that the vast thickness of its super- ficial deposits is fully exposed. In this country the valleys of the Arid Region are still being filled, and dissection has not com- menced. In China a recent climatic change, perhaps very moderate in its character, seems to have occurred, which has allowed of the formation of streams in a previously drainless region, and the streams have sunk their channels in the loess in the wonderful manner described by travellers. The similarity between the loess of China and the adobe of America is such as to warrant the conclusion that they were deposited under essentially the same conditions. That they are both mainly subaérial deposits, it seems to me, must be acknow- ledged by every one who is familiar with the geological processes now active in arid regions. Richthofen! refers the origin of the loess of China to three processes: “The first is rain water, which flows down from the upper to the lower parts, and washes away the solids which have become loosened by the decomposition of the rocks of neighbouring mountains. The second is the wind, whose extraordinary aid in accumulating dust-like divided solid material, one has frequent opportunity to notice in the regions occupied by the loess. The third agent lies in the mineral ingredients, which the roots of . grasses, by the diffusion of mineral fluids drawn up from below, assimilate, and on their decay leave behind. All these finely divided ingredients are held fast by the vegetable covering, and thence afterwards carried away only in small quantities by the wind.” The second and third of these processes are held by Richthofen to be most important; and of these two by far the greater promin- ence is given to the second, that is, to the action of the wind in transporting dust. My own studies in the arid portions of this country failed to sustain this explanation, but lead me to refer the accumulation of both the coarse and the fine deposits now accumu- lating in the drainless valleys of that region to the first hypothesis mentioned above; that is, to the transportation and deposition of fine material by ephemeral streams. That eolian transportation is an element in the process by which inclosed valleys are filled with fine debris must be acknowledged ; but that it is the principal, or even an important element, does not appear to be warranted by a study of the processes by which such deposits are now being formed. Richthofen has shown so clearly that the loess of China was not accumulated in freshwater lakes or in the ocean, that the hypotheses 1 China, vol. i. p. 78. 3850 3=Dr. G. M. Dawson— Glaciation of British Columbia. advanced by various writers who have referred its origin to ordinary sedimentation need not be considered farther. In reference to the accumulation of loess through the vital action of vegetation as advocated by Richthofen, it is perhaps sufficient to suggest, as has been done by T. W. Kingsmill,! “that plants could furnish to the mineral accumulations only what they took from it, and hence could add nothing.” Apparently no exception can be taken to this argument, unless it be that plants may add carbon derived from the carbonic acid of the atmosphere, to the soils in which they grow. The similarity between the loess of China and the adobe of the Arid Region is so close that they might properly be designated by the same name; but, as confusion has apparently already arisen from the too general use of the former name, it has been thought best to use a new term instead. Wasuineton, D.C., Noy. 27, 1888. II].—Guactation or Hic Points 1n tHe SoutHern INTERIOR OF British CoLumBiA. By Grorce M. Dawson, D.Sc., F.G.S. ; Assistant-Director of the Geological Survey of Canada. N an article published in the Grotocican Magazine for August, 1888, an outline was presented of some facts resulting from recent investigations on the glaciation of British Columbia and adjacent regions, bearing more particularly on the flow of ice in a northerly direction brought to light by explorations in the Yukon district, but touching also on the south-eastern extension of the great western glacier-mass of the continent, which I have proposed to name the Cordilleran glacier. Field-work carried out by me during the summer of 1888 has resulted in the accumulation of many new facts relating to the southern part of the area, which was at one time covered by the Cordilleran glacier, from which it would appear that it may ultimately be possible not only to trace the various stages in the recession of the main front of the great confluent glacier beneath which the interior or plateau region of British Columbia was buried, but even to follow the later stages of its decline as it became broken up into numerous local glaciers confined to the valleys of the several mountain ranges which limit the plateau. As, however, work is to be continued in the same southern part of British Columbia during the present summer, it is not at present intended to discuss these general features, but merely to call attention to the noteworthy heights at which glaciation has now been found to occur on some of the higher parts of the Interior Plateau and its mountains, and to the great mass thereby indicated for the southern part of the Cordilleran glacier. The highest point on which I had previously noted the marks of 1 Quart. Journ. Geol. Soc. London, 1878, vol. xxvii. p. 380. Dr. G. M. Dawson— Glaciation of British Columbia. 3051 glacier ice in this region was Iron Mountain, at the junction of the Nicola and Coldwater rivers, the summit of which is 3500 feet above the neighbouring river valleys, or 5280 feet above the sea.’ Evidence of the same kind—all implying the movement of a great elacier-mass entirely independent of the local features of the country —has now been discovered on several still higher points, the most elevated being Tod Mountain, situated 25 miles north-east of Kamloops, and rising 7200 feet above the sea. The actual summit of this mountain is, however, but lightly glaciated, and in this circumstance and the apparent influence which local irregularities of rock-surface have had upon the direction of striation, evidence seems to be afforded that the summit was never deeply covered by the great glacier. This conclusion is further borne out by the fact _ that a few hundred feet only lower down the same mountain, the glaciation is much stronger, and fluted rock-surfaces and other easily recognized marks of heavy glacier ice are observed. Tod Mountain is the culminating point of a region surrounded on three sides by the wide and important valleys of the North and South Thompson Rivers and Adams Lake, the nearest points comparable in elevation to it being in the Gold Range, at a distance of over 25 miles in a north-easterly direction, or nearly at right angles to the direction of the glaciation. There can be no question as to the fact that the glaciation met with at this place is due to the general or Cordilleran glacier, and it is thus evident that at one period the glacier ice must have attained a thickness of about 6000 feet in the valleys above named, while it covered even the higher portions of the irregular plateau of this part of the interior of British Columbia to a depth of at least 2000 to 38000 feet. When it is taken into consideration that evidence has already been obtained of the south-easterly motion of this part of the Cordilleran glacier for a distance of at least 300 miles to the north-west of Tod Mountain, it is apparent that the mass of névé-ice accumulated over the country north of the 55th parallel of latitude from which the southerly- and northerly-flowing extensions of the great glacier were fed must have been enormous. As previously stated by me, the condition of this part of the Cordilleran region, at the period of its maximum glaciation, must have been clearly analogous to that of Greenland at the present day, save that in the case of British Columbia it has been impossible for any large proportion of the ice to escape to the eastward or to the westward because of the bordering mountain ranges. Some of the principal new localities at which distinct evidence of the passage of the Cordilleran glacier over the southern part of British Columbia were observed during the summer of 1888, with the approximate position and height of each and the direction of motion indicated, are given below. The variation in direction found in comparing even the highest stations is generally explicable on consideration of the influence of adjacent important orographic features. A number of observations made at points somewhat lower than these here quoted show, as might be anticipated, an increasing 1 Quart. Journ. Geol. Soc. vol. xxxiy. p. 272. 302 R. Lydekker—WNotes on Dinosaurian Remains. degree of influence of the same kind dependent on the subordinate relief of the country passed over. PRG Approximate Approximate Height Direction ° Latitude. Longitude. in feet. (true bearings). High Plateau between N. Thompson and Bonaparte | IRIE Ley ehh RAIN? Biey 4340 § 20° Rivers. ean became Pe se a me a 51° 4’ | 120° 45’ 5100 § 34° E i ab 35 51° 9’ | 120° 26" 5430 S37°E * 50° 59’ 120° 25’ 5440 S 35° E Tod Mountain ais 50° 56’ 119° 55’ 7200 S 44° H High Plateau between Ndaras ay olan ° ci Secs } 51° 1’ | 119° 41 6100 S 27° E Cinder Mountain. ... ... 50° 34’ NOW By 5180 S 50° E Loadstone Peak... ... ... 49° 25’ 120° 50’ 6280 8 15° E IV.—Norsrs on New AnD oTHER DINOSAURIAN REMAINS. By R. Lyprexxer, B.A., F.G.S8., F.Z.S., ete. N the present communication I call attention to a Reptilian vertebra which does not appear to have received the notice it deserves, and also give a preliminary diagnosis of certain forms which I hope to describe more fully later on. 1. Arctosaurus Ossorni, Adams. In the year 1875 the late Professor Leith Adams described and ficured in the “ Proceedings of the Royal Irish Academy” (ser. 2, vol. ii. p. 177) an imperfect Saurian vertebra which had been ob- tained many years previously from Arctic America during the voyage of Captain Sherrard Osborn, which is now preserved in the Museum of Science and Art, Dublin. The specimen was obtained from beds of unknown but doubtless Mesozoic age at Rendezvous Mountain, which is situated at the north end of Bathurst Island in 70° 36’ north latitude. By the courtesy of Prof. V. Ball, Director of the Science and Art Museum, Dublin, I have recently had an opportunity of examining this interesting specimen, of which, by permission of the Royal Irish Academy, I am able to reproduce the original figure. In his original description of the specimen, which has suffered by lateral crushing and is otherwise imperfect, Prof. Adams considered that it indi- cated a cervical vertebra, which had lost the neural spine, the costal articulations, and the right prezygapophysis. And he then proceeds to give his reasons for regarding it as more nearly allied to Lizards than any other reptiles. My own observations confirm the conclusion that this vertebra belongs to the cervical region; but it appears that its affinities are certainly Dinosaurian. The centrum is compressed and amphiccelous, with a sharp hemal carina; and it is evident that there were free cervical ribs and a well-developed neural spine. The highly curved ventral profile and the length of the centrum indicate that the ws R. Lydekker— Notes on Dinosaurian Remains. 353 owner of this vertebra had an arched and comparatively elongated neck ; the whole facies of the specimen being essentially Dinosaurian. Moreover, in the deep median incisions between the pre- and post- zygapophyses the specimen resembles the cervicals of many of the Theropoda; while a longitudinal fissure on the right side of the centrum is highly suggestive of the crushing in of an internal cavity. That the specimen does not belong to the Celuride is quite clear ; and I am inclined to regard it as indicating a Dinosaur more or less closely allied to the Anchisauride, although, in the absence of figures of the typical American forms, it is at present impossible to institute any exact comparison. ‘The especial interest of this specimen is the evidence which it affords as to the path by which the generic types of Dinosaurs common to the old and new worlds may have passed from the one hemisphere to the other. Arctosaurus Osborni. Right lateral (A), neural (B), posterior (C), and anterior (D) aspects of an imperfect cervical vertebra ; from Bathurst Island. Nat. size. (From the Proc. R. Irish Academy.) 2. ORINOSAURUS CAPENSIS, 0. Sp. In describing certain Dinosaurian remains from the Karoo System of the Cape in 1867, Prof. Huxley (Quart. Journ. Geol Soc. vol. xxiii. p. 5) applied the name Orosaurus to a large bone which he regarded as the distal extremity of a femur, and considered to be generically distinct from the other specimens described in the same paper under the name of Huscelesaurus. This bone has been recent presented by its describer to the British Museum (No. R. 1626), and after careful examination I am convinced that it is really the DECADE I1I.—VOL. VI.—NO. VIII. 23 304 R. Lydekker—Notes on Dinosaurian Remains. proximal extremity of a left tibia. It agrees very closely, both in size and characters, with the tibia of Iguanodon Mantelli, but appears to have been solid throughout. The great expansion of the head and cnemial crest distinguishes it from the tibia of Huscele- saurus, which appears to have had a bony union with the fibula, as in Stegosaurus, and it therefore appears that the generic distinctness of Orosaurus is justified. Unfortunately, however, this term is preoccupied by the more correctly formed Oreosaurus, Peters,’ and I accordingly propose to replace it by the name Orinosaurus.? Since, moreover, no specific name was proposed by Prof. Huxley for this Dinosaur, I would suggest that it should be known as O. capensis. If I am right in regarding this tibia as solid throughout, the speci- men is of considerable interest as apparently showing a connection between the Stegosauride and Iguanodontide, and thereby serving to confirm Dr. Baur in his conclusion that these two families should be included in a single suborder. 3. IquaANoDON Frrront, n. sp. Among a series of specimens from the Wadhurst Clay near Hastings, recently collected by Mr. C. Dawson, F.G.8., for the British Museum, are an apparently associated left ilium, part of a pubis, and the imperfect sacrum (B.M. No. R. 1685), which appear to indicate a distinct species. The specimens were obtained at the village of Shornden, and although the sacrum was found at a distance of some fifty yards from the ilium, Mr. Dawson has no doubt that both specimens belonged to the same individual. The ilium, which I take as the type of this form, indicates a somewhat smaller animal than the ilium from a somewhat lower horizon which forms one of the types of I. Dawsoni.. Moreover, it differs from that ilium in that the preacetabular process merely forms a thin vertical plate, and entirely wants the horizontal inner extension found on the lower border of the latter. Again, while in I. Dawsoni the postacetabular portion forms a deep plate with a rounded termination, the corresponding portion of the present speci- men has its lateral surface terminating in a point, while the inferior border is bent inwardly to form a shelf-like projection on that side. The portion of the ilium immediately above the acetabulum is rela- tively deeper, and the acetabulum itself less well defined than in I. Dawsoni. The associated sacrum has laterally-compressed and anchylosed vertebree like those of I. Mantelli, from which species the present form is at once distinguished by the greater height of the ilium and the inflection of the lower border of the postacetabular portion. The only other named form to which this specimen could possibly belong is Sphenospondylus gracilis of the Upper Wealden, but the ilium appears to be proportionately much too large for the vertebrae, and the sacrum is different from the one which J have suggested may belong to that genus. I propose to designate this apparently new form as J. Fittoni in 1 Abh. Ak. Berlin, 1862, p. 201. 2 From the adjectival épeds, 3 See ‘Cat. Foss. Rept. and Amphib. in Brit. Mus.’ pt. i. pp. 197-199. 1% Lydekker — Notes on Dinosaurian Remains. 355, honour of the late Dr. Fitton, so well known for his labours in con- nection with the Lower Cretaceous of England. The ilium of this species, so far as its posterior portion is concerned, makes a remark- able approach to the type species of the American Camptosaurus, from which, however, this form is widely distinguished by the structure of the sacrum. 4, IGUANODON HOLLINGTONIENSIS, 0.sp. Specimens from the Wadhurst Clay of Hollington, near Hastings, appear to indicate a third species from these deposits which I propose to distinguish, at least provisionally, as I. hollingtoniensis. Some of these remains I have previously referred in the work cited to JL. Dawsoni, while others I have suggested might belong either to that species or to immature examples of I. bernissartensis. I take as the type the specimens in the British Museum numbered R. 11481 together with others belonging to the same individual numbered R. 1629, and also certain vertebree numbered R. 16382, which are also believed to have belonged to the same individual. The femur (R. 1148) agrees approximately in size with that of I. Mantelli, but is at once distinguished by its curved shaft and pendant inner trochanter, in which respects it resembles the corre- sponding bone of Camptosaurus. It is smaller and of different contour from another femur, which, from the evidence of the asso- ciated ilium, belongs to I. Dawson. The sacral vertebrae (R. 1632) are of the type of those (B.M. No. R. 811) I have previously referred to the latter species,” having flattened heemal surfaces to the centra, which were not anchylosed together. An ilium (No. R. 8116) associated with the sacrum and ischia No. R. 811, although very imperfect, shows that the preacetabular process was of the thin type of I. Fittoni, and therefore different from that of I. Dawsoni, while this ilium is decidedly different from that of I. Fitton. Finally, the dorsal vertebrze associated with Nos. R. 811 (B. M. No. R. 604) and with R. 1148, are smaller and more compressed than those of I. Dawsont. That the present form is distinct from I. Mantelli is shown by the femur; from I. Dawsoni it is distinguished by the size of the femur, and of the dorsal vertebra, as well as by the size and contour of the ilium which is apparently referable to it. The sacral vertebra, No. R. 1632, which is believed to have been associated with the type specimen, distinguishes this species from I. Fittoni ; this being confirmed by the sacrum No. R. 811, which is now known to have been associated with vertebree and an ilium which are clearly not referable to I. Dawsoni, and still less to I. Fittoni. Iguanodon hollingtoniensis approximates in the structure of its femur, ischia, and sacrum to Camptosaurus, but is distinguished by the peculiar pollex of Iguanodon, on which account I include it in the latter genus. I am at present unable to say definitely whether the unnamed imperfect skeleton in the British Museum from Hollington numbered 1 ‘Cat. Rept. etc.,’ op. cit. p. 217. o Ops His a NOR 3856 A. J. Jukes-Browne—Granite in a Boring at Bletchley. R. 331 belongs to I. Fitioni or I. hollingtoniensis, although, as J have remarked in the work cited, it is certainly distinct from I. Mantelli. I may add that the bone in that skeleton catalogued as a fragment of an ilium proves to be the glenoidal portion of the right coracoid. V.—Tue OccurRENcE or GRANITE IN A Borine at BLETCHLEY. By A. J. Juxus-Browns, B.A., F.G.S. N the winter of 1886-7 a boring was made at Bletchley Junction for the London and North-Western Railway Company, and acquired importance from the report that, after passing through the Oxford Clay, it had entered a mass of granitic rock.? Probably many readers of this MacazinE wondered why no detailed account of the boring was published after this announcement; but the reason was, that when inquiries came to be made, some uncertainty was found to exist as to the position and mode of occurrence of the granitic rock. My attention was recently called to the boring by learning that the water obtained from it was salt. I then ob- tained all the information I could with regard to the rocks passed through, and think the results are of sufficient importance for pub- lication. The interest naturally centres in the supposed occurrence of granitic rock at a depth of less than 400 feet from the surface, and it seems desirable that the facts with regard to this should be placed on record. The boring was made by Mr. Ebenezer Timmins, of Runcorn, under the superintendence of Mr. F. W. Webb, the Engineer of the L.N.W.R. Company. The work was personally directed by Mr. Arthur Timmins, to whom I am indebted for the particulars given below; Mr. A. Timmins tells me he had the first handling of all samples which were brought up, and that he took some trouble to ascertain the nature of the rocks through which the boring was carried, making analyses of several of the specimens himself. All this information he has generously placed at my disposal, and the following is his account of the boring. Old well 148 feet deep. Boring commenced from bottom of well. Level of surface about 260ft. O.D. :— Thickness. Depth. ft. in. fis 1 Depthyottold wells eee ssececs — 148 0 De LBS InN sedoodnobsoscucoacosqees 8 0 156 0 See BIMENC ayAmsn eects awatermcmeancness 9 0 165 0 AN BlAaCkKSHaleaeiake vs decease tees eee ee 1 0 166 0 5, allan: CAN) Gugsbseaacoossnedaasbone6C 2 6 168 6 Go Leieonvatt, Clan? SSsandnbooddeecrcocaaudanade Wf) 186 90 (ee Bluenlimestonesascccesecesscecneee ee 1 0 187 0 Slo TBRONWid ClEly GobposusbaocdababeanosHoode 5 0 192 0 Oe Blwewimestonemecssseneseeeetectencete 12 0 204 0 MOM MBlie\ clayey sus haces seeenaceeeeetes 8 0 212 0 ILS Joly IWS KONE Kaspsconascosbcsoncunce | OY) Deh) IPAS TERN EN ERY Gogancdcobercseascoosesandesee 6 3 224 0 oe BlueMimestoner ewe ieee nce ane 1 0 225 0 1 Op. cit. p. 226. * See Prof. Hull’s letter, Grot, Maa. Dec. III. Vol. LY. p. 189 (1887). A. J. Jukes-Browne—Granite in a Boring at Bletchley. 357 (ifs auily "atte. // alle 14. Blue clay with septaria ............ 36 0 261 0 vl5a Bluevlimestone suc eceeeeaseacescassce'« 1 0 262 0 16. Blue clay with septaria ............ 40 0 302 0 ey Bile? limestome see ccceececens successes 3 3 805 6 18. Blue clay ............. Netteacesatacne 4 6 310 0 19. Blue limestone .............e0cceeeeees 1 0 dll 0 P40), 1S CNY, | Sdhoc-cenecbenecogsosdeceoore 45 0 3856 0 91. Indurated bluish limestone......... Day 8) 378 5 Ti. Grain AKO Lecanoaceteouseoseeoneen Pi 7 400 0 Dem Olaye ans ae MEE Me dha Teh) ADIL ga, QAM Greate TOCKM pateener cubed ene sels Gie2) 407 2 MBs (CIENT toceecdcecanobecoobactob ooo ncoRo.oc 2 10 410 0 The following observations are chiefly by Mr. A. Timmins, with a few remarks of my own on the samples which he sent me, and which are now in the possession of Prof. A. H. Green at Oxford. No. 3 was a very hard blue clay. No. 4. A bituminous shale containing iron pyrites. No. 9. Sample preserved, a dark grey limestone, with well-marked oolitic structure, several Echinoderm spines, and some shell fragments. No. 11. Samples preserved probably from this bed are of a grey shelly and partially oolitic limestone. No. 13. Sample preserved from 224 feet, a light grey crystalline limestone, very hard, with glistening surfaces of calcite, possibly parts of Echinoderm tests and spines. No. 14. A very hard clay full of septaria and pyrites. No. 16. The same as No. 14. Samples of the septaria preserved and analysis made by Mr. Timmins with following result :— Insoluble siliceous matter ............cc0.c0 ceseeeee 9°800 HeOn(orisinallypHeCOsereresscceseescresiasececseese) O4G41O He> Oy ions Neronid Ogee cn semecths odes selsst-eesh caceeees 33425 PAN TIMMINN Baye iy cite ecanwe sak arc dae ste tcawedeumendacmeas 3°392 Callciumicarbonatciyesssiereccetavsancere aces 17-050 IMG o Mesum CATO ON atCssesHeadeeatectnesaescsoess 2-294 100°374 Nos. 18, 19, and 20. These beds were full of fossils, but all the larger specimens were broken up by the chisels; those preserved are chiefly fragments of the stems and arms of small Crinoids, with several pieces of small Belemnites and fragments of bivalve shells. They are just such fossils as would occur near the base of the Oxford Clay. No. 21. No sample preserved, but described by Mr. Timmins as a “ very hard limestone.” At about 360 feet it contained hard nodules or boulders of stone of a dark buff colour and having cracks filled up with calcite; they were calcareous and ferruginous, with only 15 per cent. of insoluble matter. A sample from 3870 feet had the following composition :— Amsolmblexmattenymaadsaccmeeeasece cena ee ee aaeecee 53-48 Oxidexon ironyandeal mina eee eee eee eae 20°40 Calciummcanbonatemensseeeecce eeeeeee eee ae 26:06 99-94. My colleague, Mr. A. G. Cameron, has sent me a piece of Kellaway rock, from Kempton, near Bedford, which is a very hard, compact, 308 A. d. Jukes-Browne—Granite in a Boring at Bletchley. greyish-brown ferruginous and siliceous limestone; the general character of this rock is such as to suggest a chemical composition similar to that of the above analysis of the ‘‘indurated limestone” in the boring, and it has cracks filled with calcite. — Mr. Timmins says that from the foreman borer’s account it would appear that this bed gradually got harder and harder till they came on to the “ granitic rock” at 378’ 5”, and that the depth of colour also increased to a rusty brown. No. 22. The following are Mr. Timmins’ notes on this rock :— ‘“‘The boring of this bed proved a very tedious operation, averaging about five inches a day, and owing to this incessant grinding of débris, large particles of rock were not to be expected: what samples there are were found after sifting the whole débris through a sieve of 1225 meshes to the square inch. The analysis of a bulked sample between 378’ 5” and 390 feet is as follows: INMSONMIGIE WHEE sonondnasosococaacneoanbencennseeboe 80°106 Oxide of iron and alumina...................00.0000+ 11°514 Calexum\carbonatem eee 3838 Magnesium carbonate .....-......2---+e.0sse+rcsr2= 640 Alkalies, ete., not determined ..............sseeces 3°902 100:000 Before analyzing this sample, all particles of steel and iron from the boring tools and casing tubes were extracted as well as possible with a magnet; but it is possible that some of the 114 per cent. of iron is derived from the mechanical appliances in use.” Samples of this material are preserved in bottles, the larger fragments are undoubtedly pieces of a granitic rock; the finer material which has passed through the sieve is of a brownish colour, and has the appearance of a pounded, fine-grained ferruginous sandstone. More will be said of this in the sequel. Bed 24 was similar to bed 22, but was not so hard and compact, so that more rapid progress was made through it. Beds 23 and 25 were clays with a blue colour when first brought into daylight, but after a few days in the air the colour began to fade, and through gradual gradations it arrived at a light brownish tint ; this is probably due to the oxidation of the iron. An analysis of one of these clays gave the following results : Insoluble siliceous matter ..........cce.eseeeee-eeees 79°807 Oxides of iron and alumina ................0eeeeee. 13°778 Calcrmmiicarbomate om -tee-eereeeeeeceeceer ence 2-997 Midomesiumy carl onate wancecn-ecsecseecutesseeseeon 1-718 98-300 Mr. Timmins remarks that it had somewhat the aspect and com- position of a fire-clay. As the sample sent to me had rather a powdery felspathic look about it, I forwarded it to Prof. Bonney, who reported that it appeared to be an ordinary clay, “such as might well occur in the Jurassic series”; and that it was not a decomposed igneous rock or felspar rolled in situ, and had certainly not been baked by contact with igneous rock, as it must have been if the beds of “ granitic rock” were intrusive sheets. A. J. Jukes-Browne—Granite in a Boring at Bletchley. 359 To complete the record of the boring, it may here be mentioned that water was found at the depth of 390 feet 9 inches in the first bed of “granitic rock,” and again in the lowest clay at 410 feet, or more probably from a bed immediately underlying this clay, but not pierced. In both cases the water was very salt and unfit for use, so that the boring was abandoned and a coffee-house is now built over the site. We may now revert to the so-called “granitic rock.” It has already been stated that fragments of such a rock do certainly occur among the samples, and there seems no reason to doubt that these fragments were brought up from the depths named. As evidence on this point I quote a letter from Mr. A. Timmins to Mr. Cameron, dated November 19, 1886 :—“‘I enclose a sample of the strata from present depth (390ft.) ... I make it out as hornblendic granite, _ and have had suspicions for some time. A few weeks ago my father brought home a piece of stone similar to the sample, and said that he was told by the foreman that it had come up the boring. Ever since I have sieved the samples sent to me, and Saturday was the first time, since that above mentioned, that I was able to get any larger pieces. My suspicions were at once confirmed, and I] make out that we have bored through 10 feet of this granitic rock.” | With this evidence we may I think take it for granted that pieces of a granitic rock did come up from the depths stated in the account of the boring. Next as to the nature of the rock: two small fragments were sent to Prof. Bonney, who was kind enough to examine them and reported as follows: “The fragments which you have sent me are of a rock closely allied to granite. As far as I can see with a strong lens they are likely to belong to the microgranulite of Fouqué and Lévy—that is, a rock with felspar quartz and mica or hornblende (probably the latter in this case) in a sort of fine mosaic; the in- dividual grains not being very definite in form unless showing a micrographic structure. It is not a true granite, and yet itis rather too crystalline for a normal quartz-felsite ... I never saw one like it among the Midland Paleozoics, but it has a general resem- blance to the rocks of the Narborough district.” There is no proof however that the whole of the thickness given to ‘“ granitic rock” in Mr. Timmins’ account of the boring consisted of the rock above described ; there is indeed strong evidence for the belief that it did not. In the first place I am informed by Mr. Cameron that he went over to Bletchley at the time they were boring through this rock, and selected small samples out of the foreman’s box from depths of 391 feet and 393 to 396 feet. These he has kindly sent to me, pointing out that they are simply sandstones, without any trace of granitic fragments or minerals. The first is a light-coloured and fine-grained sandstone composed of small quartz grains with ferru- ginous staining; the second is a dark brown ferruginous sandstone. Both are such rocks as occur in the Kellaways Beds at the base of the Oxford Clay, and the only way of reconciling their existence with the recorded occurrence of granitic rock at about the same depth 360 which was regarded as allied both to the true Cryptodira and to the Pleurodira. 3. “On the Relation of the Western Beds or Pebbly Sands of Suffolk to those of Norfolk, and on their Extension inland ; with some Observations on the Period of the final Elevation and Denuda- tion of the Weald and of the Thames Valley.” By Prof. Joseph Prestwich, M.A., D.C.L., F.R.8., F.G.S. Part I. The author in this, the first part of his paper, described the Westleton beds of the Hast Anglian coast. He commenced with a review of the work of previous writers, especially Messrs. Wood and Harmer, and the members of H.M. Geological Survey, including Messrs. H. B. Woodward, Whitaker, and Clement Reid. In dis- cussing this work, particular attention was paid to the Bure-valley beds, which were considered as a local fossiliferous condition of the Pebbly Sands; but the term is not so applicable to these sands as 378 Reports and Procecdings— that of the “ Westleton and Mundesley Beds,” which the author proposed in 1881. The Westleton Beds were carefully described, as seen in coast- sections in Hast Anglia, proceeding from south to north, and the following classification was adopted :— (1. Laminated clays, sand, and shingle with plant-remains The Westleton and freshwater shells (the Arctic forest-bed of Reid). and Mundesley 2. Sand and quartzose shingle with marine shells (the series 4 Leda myalis bed of King and Reid). (the Mundesley 3. Carbonaceous clay and sands with flint-gravel and section of it). pebbles of clay, drift-wood, land and lacustrine shells and seeds (the Upper freshwater bed of Reid). 4, A greenish clay, sandy and laminated in places, con- g Ni yj P taining abundant mammalian remains, and drift-wood, ee | with stumps of trees standing on its surface (the (exclusive ae Nae 4 forest- and elephant-bed of authors; the estuarine division, in part, of Reid). 5. Ferruginous clay, peat, and freshwater remains and ( gravel (the Lower freshwater bed of Reid). The Westleton Beds were found to rest with discordance on various underlying beds; in places on the Forest series, elsewhere on the Chillesford Clay, whilst occasionally the latter had been partly or entirely eroded before the deposition of the Westleton Beds. In the north, where the present. series dies out, they come in contact with the so-called Weybourn Crag, which the author supposed to be the equivalent of the Norwich Crag. A similar discordance has been noted between the Westleton Beds and the overlying glacial beds, so that the former mark a distinct period, characterized by a definite fauna, and by particular physical con- ditions. The Westleton Beds being marine, and the Mundesley Beds estuarine and freshwater, the author proposed to use the double term to indicate the two facies, as has been done in the case of other deposits. But these facies were found to be local, and the most persistent feature of the beds is the presence of a shingle of precisely the same character over a very wide area. By means of this the Westleton Beds can be identified far beyond Hast Anglia, and where there is no fossil evidence, and they throw considerable light on important physiographical changes. The author described the composition of the shingle, which, unlike the glacial deposits, contained pebbles of southern origin. The paper concluded with a list of fossils, excluding those of the Forest-bed (the stumps of which, the author considered, were frequently in the position of growth). Should the Forest-bed eventually prove to be newer than the Chillesford beds, it was maintained that the former must be included in the Westleton series, and its flora and fauna added to the list, whilst if, on the contrary, the Forest-bed should be proved synchronous with the Chillesford Beds, it must be relegated to the Crag. The second part of the paper will treat of the extension of these beds into and beyond the Thames Valley, and on some points con- nected with the physical history of the Weald. of above). ees Sty Geological Society of London. ovo II.—June 19, 1889. —Prof. J. W. Judd, F.R.S., Vice-President, in the Chair.—The following communications were read :— 1. “On Tachylyte from Victoria Park, Whiteinch, near Glasgow.” By Frank Rutley, Esq., F.G.S. This paper dealt with the microscopic characters of certain thin tachylytic selvages occurring on the margins of white-whin (basalt) veins which traverse Carboniferous shales in Victoria Park, and which have already been described in some detail by Messrs. John Young and D. Corse Glen. The white-whin veins, which sometimes are not more than an inch in breadth, are found to become gradually more vitreous in passing from the middle to the sides of the veins. Near the margin they become densely spherulitic, the spherulitic band on either side of the vein being followed by a less spherulitic and more glassy band, the vitreous matter of which appears nearly or quite colourless. A sharp but irregular boundary-line follows, beyond which lies a band of a more or less deep brown or coffee- coloured glass, which the author considers to have resulted from the fusion of the shale, two narrow vitreous bands of different origin being thus developed side by side on each side of the vein, the colourless bands representing the chilled margins of the vein, the brown bands the fused surfaces of the walls of shale. The author only suggested this as a plausible explanation of the microscopic phenomena. An analysis of portion of one of these whin veins with its adherent tachylyte, made by Mr. Philip Holland, was appended to the paper. 2. “The Descent of Sonninia and of Hammatoceras.” By 8. 8. Buckman, Esq., F'.G.S. The author reviewed the history and literature of the genus Sonninia, Bayle, which was founded to receive the Ammonites of the Sowerbyi-group, formerly classed, together with those of the Insignis- group, in the genus Hammatoceras. The reasons why the genus Sonninta is not descended from Hammatoceras, or from Haugia (Variabilis-group), were set forth. Then, proceeding to trace out the life-history of Plewroceras, Amal- theus, and Sonninia, as shown by their inner whorls, the author arrived at the conclusion that these three genera were descended from a common source, and that they form three branches from one stem. The development of the genus Hammatoceras, sensu stricto, was then traced out, and its descent shown to be from the genus Deroceras, . which is in accordance with the general ideas upon the subject. The difference in the descent of Sonninia and Hammatoceras was taken to justify the separation of the former from the latter. The genus Sonninia would be correctly placed in the family Amaltheide ; while the genus Hammatoceras would be placed in the same family as Stephanoceras. Of the numerous new species belonging to the genera Sonninia and Hammatoceras, certain forms, necessary to elaborate the ideas set forth above, were described and definitely separated. The paper also touched upon certain other facts connected with Hammatoceras, Sonninia, and cognate genera. 3880 Reports and Proceedings—Geological Society of London. 3. “Notes on the Bagshot Beds and their Stratigraphy.” By H. G. Lyons, Esq., R.E., F.G.S. The author deplored the necessity of quitting the area which he had studied before completing his observations, and wished to place his results at the disposal of other workers. In a previous paper he had discussed the beds at their southern outcrop, over a small area, and showed that there the Bagshot and London Clay strata remained of constant thickness, and dipped northwards at an angle of about 21°. He had since examined the country between Aldershot and Ascot over an area of about fifteen miles square, and attempted by contouring the surface of the Middle Bagshot beds (which showed a nearly constant thickness of 60 feet over the area), to give the form into which the beds had been pushed by the different slight flexures which might occur. After giving details of the heights at which this surface was found, he concluded that an anticlinal of which the axis pointed upon Windsor Castle, appeared to pass through the Swinley and Wellington College area, and probably to Hazeley Heath ; and that a synclinal started by Minley and Hawley, and ran by the Royal Albert Asylum, Gordon Boys’ Home, upon Ongar and Row Hills, and Woburn Hills ; and that another anticline ran to St. George’s Hill, Weybridge. The author had attempted to map the southern and eastern limits of the Upper Bagshot beds, and claimed a much greater extent for these beds in those directions than had been assigned by the members of the Geological Survey. The outcrop of the beds was described in some detail, and the occurrence of outliers on Knaphill Common, by Donkey Town, on Chobham Common, and on Staples Hill, was noted. 4, “Description of some New Species of Carboniferous Gastero- poda.” By Miss J. Donald. Communicated by J. G. Goodchild, Esq. The Gasteropoda described in this paper have, with one exception, been collected by Mr. John Young from the Upper Limestone Series of Scotland. After discussing the characters of the genus Orthonema, Meek and Worthen, the following forms were described: Orthonema pygmea, n. sp.; O.?, n. sp.; Murchisonia turriewlata, de Kon. (Yore- dale Shales, Askrigg, Yorkshire) ; M. turriculata, var. scotica; and M. compacta, n. sp. d. “ Cystechinus crassus, a New Species from the Radiolarian Marls of Barbadoes; and the evidence it affords to the Age and Origin of those Deposits.” By J. W. Gregory, Esq., F.G.S. In this paper the discovery of a species of Cystechinus from the Radiolarian earth of Barbadoes was recorded. The specimen is now preserved in the National Collection, South Kensington. The form was described and distinguished from the three modern species which were found during the ‘Challenger’ Expedition. The latter have shown that the bathymetrical range of the genus is from 1050 to 2225 fathoms. The author gave proofs that the specimen really came from the Radiolarian marl, and not from the overlying Coralline Limestone, and after discussing the age of the marl, as inferred by Prof. H. Obituary—Ur. Henry William Bristow. 381 Forbes, from an examination of the Mollusca, and by Prof. Haeckel after studying the Radiolaria, gave his reasons for supposing that it is in reality more modern than these authors supposed, and may be referred to the Pliocene or Pleistocene. Though Cystechinus crassus possessed plates of greater thickness than those of the previously described species, the ambulacra were apetaloid, and the author concluded that though an inhabitant of seas of less depth than those in which the modern forms occur, it may be fairly considered to have been a dweller in deep seas, and to indicate that the Radiolarian deposit is a true deep-sea ooze. C@E ea Sa @ aN sen Ni @ sane ARS a A PALAONTOLOGICAL RECORD. Str,—Now that Paleontology has become so complex a science, and new species are from day to day described in various parts of the world, is it not desirable that some International Record of them should be published at stated intervals? We would suggest that the matter be taken up by the Inter- national Geological Congress; and if this be adopted, every one who describes a new species of fossil should send in the name and full references to the work in which it was published and figured, with accounts of the locality, geological horizon and biological order of the species. In this way we should have an authentic register of new species, that would be of great value to all students of Paleontology; and, in short, “facilitate the preparation of that general list of all described fossils which is at present one of the greatest desiderata in geological science.” ! RupoiF ScHAFER. Horace B. Woopwarp. @rS seo PAS Eas HENRY WILLIAM BRISTOW, F.R.S., F.G.S., Late Director of the Geological Survey of England and Wales. Born, May 17, 1817. Diep, June 14, 1889. HE name of H. W. Bristow will always be associated with the history of the Geological Survey, on which he served for a period of forty-six years. During the first few years of the official existence of the Survey, De la Beche had to depend to a large extent on voluntary or temporary assistance, but gradually he gathered around him a permanent staff of field-geologists and of others occupied in museum-work. Among those attached to the Survey in these early days were John Phillips, Ramsay and Aveline. In 1842 Mr. Bristow, then nearly twenty-five years of age, was appointed an Assistant Geologist, and during the next few years [Sir Warington | Smyth, Baily, Edward Forbes, Jukes, Selwyn and others joined the staff, whose headquarters were then situated in Craig’s Court. 1 See Address to the Geol. Soc, 1889, by W. T. Blanford. 382 Obituary—Ur. Henry Wiliam Bristow. Mr. Bristow was born on May 17th, 1817, and was educated at King’s College, London, where, in 1840-41, he obtained certificates of honour in the departments of civil engineering and applied science. His father, Major-General H. Bristow, belonged to an old Wiltshire family, and had served in the Peninsular War. Commencing Geological Survey work in the neighbourhood of Radnor, on the Old Red Sandstone and Silurian rocks, Mr. Bristow was shortly afterwards transferred to the Jurassic regions of Glouces- tershire and Somerset, mapping portions of the Cotteswold Hills near Wotton-under-Edge and Chipping Sodbury, and of the Oolitic district near Bath. In these areas he received guidance from John Phillips and William Lonsdale. Still later he proceeded to the south coast, and working eastwards of Lyme Regis, he personally surveyed the greater portions of Dorsetshire, and eventually much of Wiltshire, Hampshire, and the Isle of Wight, and parts of Berkshire, Sussex, the Wealden area, and eastern Hssex.! In the course of this extensive survey all the subdivisions of the Jurassic, Cretaceous, and Lower Tertiary strata came under notice ; and students who have subsequently paid attention to the structure of these tracts, whether along the fine cliff-sections of the Dorsetshire coast or inland over the Isle of Purbeck, the Ridgway, or Bridport, have borne testimony to the care and accuracy with which Mr. Bristow has depicted the geology. For it must be remembered that, excepting the small geological maps of Buckland and De la Beche, of Webster, Fitton, and Mauntell, the detailed structure of the district had all to be unravelled. Nor was this a simple and easy task, considering the unconformable overlaps (or oversteps), and the effects produced by anticlinal disturbances and faults. In fact, no one, without actual experience of the process of geological mapping, can fully realize the amount of physical toil and mental labour in- volved in tracing the geological boundaries and faults in a region where so many subdivisions occur, and where they appear often in irregular and unexpected juxtaposition. It is Mr. Bristow’s field-work which will remain as a lasting memorial of his devotion to geological science. If his literary work on the Survey appears small, it must be remembered that in the early days of the Survey, the geologists were moved rapidly on from place to place, so that unfortunately little time was allowed for making detailed notes of the strata, and still less for observing the mode of occurrence of the organic remains. Mr. Bristow’s intimate knowledge of the lithology of the stratified rocks is shown in the portions he contributed to the Descriptive Catalogue of the Rock Specimens in the Museum of Practical Geology. The preparation of the Survey maps, however, was supplemented by numerous sections, longitudinal and vertical, which Mr. Bristow constructed with much skill and neatness to illustrate and explain the geology of the regions he had surveyed. The Purbeck Beds were especially illustrated in this way, and while the paleontology 1 The Sheets of the Geological Survey Map on which Mr. Bristow was principally engaged, are Nos. 1, 5, 7, 9, 10; 11, 12, 14, 15, 16, 17, 18, 19, 35, 36, and 56. ee Obituary—Ur. Henry William Bristow. 385 of these beds was studied by Edward Forbes, the strata themselves were measured in great detail by Mr. Bristow, partly in conjunction with the Rev. Osmond Fisher, and partly with the aid of Mr. Whitaker. In like manner sections of the Tertiary strata in the Isle of Wight were prepared, while the paleontology was worked out by Forbes. The results of this work were published by Forbes, while the geology of the whole island was afterwards described by Mr. Bristow. The task of his later years had been to prepare a new edition of his Geology of the Isle of Wight; and this is now nearly ready for publication, having been revised and considerably augmented by Messrs. C. Reid and A. Strahan, who have lately re-surveyed the island on the scale of six inches to a mile. In later years other areas surveyed by Mr. Bristow were illus- trated by Memoirs. In conjunction with Mr. Whitaker, parts of Berkshire and Hampshire were described, and Mr. Bristow also contributed notes to the Memoirs on the Geology of the London Basin, the Weald, and East Somerset. Considerable attention was given to the Rhetic Beds by Mr. Bristow, and in company with Mr. Etheridge, he visited the principal sections in the south of England and Wales, measuring the beds in detail, and eventually publishing the records. At the suggestion of Sir Roderick Murchison, in 1864, Mr. Bristow recommended that the name Penarth Beds be applied to the British representatives of the Rheetic Beds. He subsequently was occupied for several years in mapping these strata in parts of Glamorgan- shire, Gloucestershire, and Somerset, at the same time revising the geological maps over the regions visited. Notwithstanding his arduous out-door occupation Mr. Bristow utilized his leisure hours in the preparation of a ‘Glossary of Mineralogy,” which was published in 1861. This book was at once well received, proving to be an exceedingly useful work of reference, from its convenient arrangement, and the accurate and concise information given. The author had made considerable progress towards a new edition of the work. Other works of a more popular nature likewise engaged his attention. In 1869 a translation by him of L. Simonin’s “ La Vie Souterraine”’ was published, under the title of ‘“ Underground Life ; or Mines and Miners,” a work which was adapted to the then present state of British mining. Three years later (1872), he produced a translation of Louis Figuier’s ‘“‘ World before the Deluge,” contributing a fresh chapter on the Rhetic or Penarth Beds. In previous years Mr. Bristow had also written mineral- ogical articles for Brande’s Dictionary of Science, and Ure’s Dictionary of Arts, Manufactures, and Mines. He also largely assisted the late Mr. Damon in his Geology of Weymouth, con- tributing much general information and some sections of the strata. It only remains to be mentioned that after five years’ service on the Geological Survey, Mr. Bristow was in 1847 promoted to the rank of Geologist. Twenty years later (1867) he was appointed District Surveyor, taking charge of the southern counties. In 1872 he was made Director for England and Wales, during the tenure 384 Obituary—Mr. Henry William Bristow. of which office he saw the completion of the Geological Survey of the country on the one-inch scale. Retiring in July, 1888, he enjoyed but for a brief period his well-earned repose. A sudden stroke of paralysis was the immediate cause of his passing away, after a lingering illness, on June 14th, in his seventy-second year. Mr. Bristow was elected a Fellow of the Geological Society in 1845, and of the Royal Society in 1862. Unfortunately afflicted with partial deafness, he was unable to hold free intercourse with his brother geologists; hence he seldom took part in the meetings of the Geological Society, although he served on the Council for a short time. He received a Diploma from the Imperial Geological Institute of Vienna, and from the King of Italy the Diploma and Insignia of an officer of the Order of SS. Maurice and Lazarus. For several years, and until the close of his life, he was Hxaminer in Geoteey, for the Science and Art Department. LIST OF PAPERS AND GEOLOGICAL WORKS BY H. W. BRISTOW. 1842,.—1. A Descriptive Catalogue of the Minerals in the Museum of King’s College, London. 8vo. pp. 64. London. 1859.—2. Explanations of Sections (Horizontal and Vertical) of the Strata in the Isle of Wight. Geol. Survey. 8vo. London. 1861.—8. A Glossary of Mineralogy. 8vo. pp. xlvii. 420. London. 1862.—4. The Geology of the Isle of Wight. Geol. Survey Memoir. 8vo. London. 5. Notes on the Auriferous Mines and Deposits of the Spanish and Portu- guese Estremaduras. Mining and Smelting Mag. vol. iil. pp. 97-100, 1382-185. 1864.—6. On the Rheetic or Penarth Beds of the Neighbourhood of Bristol and the South-west of England. Groz. Mac. Vol. I. pp. 236-239; Rep. Brit. Assoc. for 1864, Sections, p. 50 (1865). 1866.—7. Note on Supposed Remains of the Crag on the North Downs, near Folkestone. Quart. Journ. Geol. Soc. vol. xxii. p. 553. 1867.—8. On the Lower Lias or Lias-Conglomerate of a Part of Glamorganshire. Quart. Journ. Geol. Soc. vol. xxii. pp. 199-207. 1871.—9. Evidence given in 1869 before the Coal Commission ; and Table showing the ‘Thickness of the Secondary Strata in the Southern Counties of England. Rep. Coal Commission, vol. 11. pp. 445-462. 1872.—10. Table of British Sedimentary and SHlaccilterons Strata. The Description of Life Groups and Distribution. By R. Etheridge. London. 18738.—11. Table of British Strata showing their Order of Superposition and Relative Thickness. London. 12. Hunstanton ‘‘ Red Chalk.” Guroz. Maa. Vol. X. pp. 189, 190. 13. Notes on his Survey of the [Brixham] Cave. Phil. Trans. vol. elxiii. pp. 496-497. 1875.—14. Deep Boring in Prussia. Gurot. Mac. Dec. II. Vol. IT. pp. 95, 96, 140. 1880.—15. Geological Map of England and Wales (founded on the Map published by the | Society for the Diffusion of Useful Know lege) Part 4 of Letts’s Popular Atlas. London. JOINT WORKS BY H. W. BRISTOW AND OTHERS. 1858.—16. A.C. Ramsay, H. W. Bristow, and H. Bauerman, Descriptive Catalogue of the Rock Specimens in the Museum of Practical Geology. 8vo. London. Edit. 2, 1859, and Edit. 3, 1862 (with part by A. Geikie). 1862.—17. H. W. Bristow and W. Whitaker, The Geology of Parts of Berkshire and Hampshire. Geol. Survey Memoir. 8vo. London. 1869.—18. H. W. Bristow and W. Whitaker, On the Formation of the Chesil Bank. Grot. Mac. Vol. VI. pp. 433-438, 574, 575. 1871.—19. H. W. Bristow and H. B. Woodward, Remarks on the Prospects of Coal to the South of the Mendips. Gnrox. Maa. Vol. VIII. pp. 500-505. Bone Geol Mas 1889. GeoWest & Sone del. lith et imp. DEVONIAN ENTOMOSTRACA THE GEOLOGICAL MAGAZ ZINE. NEW SERIES. DECADE III. VOL. VI. No. IX.—SEPTEMBER, 1889. ORIGINAL ARTICLIHS. I.—On some nEw Devonian Fossits. By Prof. T. Rurert Jonzs, F.R.S., and Dr. H. Woopwarp, F.R.S. (PLATE XI.) J. Ecutnocarts Wurippornei. Plate XI. Fig. 1. | N this specimen one valve (the left) and a part of the dorsal region of the other, remain visible; the rest of the right valve being bent down, broken, and imbedded in the matrix. ‘This is a finely micaceous, non-calcareous, grey mudstone, weathering fer- ruginous towards one edge, which pully abutted on a crack open to water and atmosphere. The fossil, in the grey portion is darker than the matrix, and fairly represents the test of half of the carapace, with only a very thin’ lamina wanting, a broken edge of which is traceable (with a lens) near the ventral margin. This left valve measures 9:2 by 7-4 mm. Jt is subcircular, more boldly curved on the ventral than on the posterior margin, whilst the front margin is somewhat truncate,’ having a nearly straight edge from above downwards before it bends round into the ventral curve. The dorsal border was probably straight along two-thirds of its length, but has been crushed against the other valve and somewhat distorted. A distinct, narrow, mar- ginal rim is present,—thickened and raised on the front margin, and flatter on the ventral and hinder margins. The convexity of the surface is interrupted by several elevations and depressions. In the antero-dorsal region are five unequal swellings; one, large and pyriform, is most noticeable, and a small subtriangular swelling in front of it fills the antero-dorsal angle ; behind these a triangular space is occupied by three other unequal prominences; and altogether these represent the locality of the important cephalic (buccal or gastric) organs, and their muscular attachments. Behind the swellings are two ridges on the valve; one along its median line, and the other, parallel, but somewhat curved, on the ventral region. The swellings are each ornamented with a few small tubercles, somewhat wide apart. The ridges also bear such little tubercles ; the upper (straight) ridge having about nine, and the lower (curved) ridge has six. This fossil belongs ‘evidently to Echinocaris,’ Whitfield (1880) ; 1 For the latest account of this genus and the several species here mentioned, see Geol. Surv. State of New York, Paleontology, by Prot. James Hall and J. M. Clarke. vol. vil. 1888, pp. 166-181, plates 28-30. See also our Sixth Report (for 1888), Rep. Brit. Assoc. 1889, p. 180. DECADE IIIL—vVOL. VI.—NO. TX. 25 886 Prof. T. R. Jones and Dr. Woodward—Devonian Fossils. but it differs from E. punctata, Hall (fig. 2, after Beecher, about two-thirds of the natural size), in being rounder behind, and truncate in front,—in the arrangement of the cephalic prominences, —and particularly in having two parallel ridges, instead of one - sigmoidal ridge. So also it differs from E. sublevis, Whitfield, H. condylepis, Clarke, E. multinodosa, Whitfield, and E. Whitfieldi, Clarke. H. pustulosa, Clarke, has only one tuberculate ridge. E. socialis, Beecher, has the two parallel ridges, and the valve is slightly pustulose here and there; but it is smaller and more ovate than the specimen under notice ; and the cephalic swellings, though analogous, are not identical. As it is evidently a new species we propose to name this unique fossil from Devonshire Ecuinocaris WHIDBORNEI, after the Rev. G. F. Whidborne, F.G.S., who drew our attention to the specimen, and first recognized its true affinities. Mr. J. E. Marr, Sec.G.S., informs us that this rare fossil was found by Mr. Dufton in the leaden-blue shales of the Lingula- squamiformis beds in a quarry near Sloly, close to the three-milestone on the Barnstaple and Ilfracombe road. The shales (he adds), which are here interstratified with very micaceous frilled sandstones, belong to the Cucullza-zone of the Marwood Beds. The specimen is preserved in the Woodwardian Museum, Cambridge, and has been kindly lent to us by Prof. T. McKenny Hughes for examination and description. II. Beyrtcnta Drvontca, sp. nov. Pl. XI. Figs. 3-5. Figs. 8, 4, 5 show internal casts of some large Beyrichie from the Devonian strata near Torquay, in Devonshire, in different states of preservation. Nine or ten other such specimens were sent to us for examination by Thos. Roberts, Esq., F.G.S. They are all preserved in the Woodwardian Museum, Cambridge, and are imbedded in a finely micaceous, purplish-grey, schistose mudstone, weathering red, from the New Cut, above Meadfoot, Torquay. The fossils occur, sometimes on a cleavage-plane, more frequently on the bed-planes, compressed and distorted by pressure; and therefore rarely (as Fig. 3) escape some such modification. The test of the valves has gone, and the casts and moulds are both coated with ruddle, which in some cases seems to represent the test. Figs. 8a—e. This is the internal cast of a simple three-lobed Beyrichia (4 mm. long, by 2 high), having, in the curved ventral junction of the two hinder lobes, some analogy to both B. Buchiana, Jones, and B. Kledeni, var. antiquata, Jones,—which are of Upper Silurian age. In the shape and size of the valve, however, and the proportions of the lobes, it differs from both. Another good cast (6 xX 2:5 mm.) differs slightly from Fig. 8, appearing sharper in front and blunter behind, if looked at on edge,—that is, the anterior lobe is rather further from the front margin, and the posterior lobe nearer to the hinder margin. The impression from out of which some of these and other casts have come indicate no other characters of the surface except what Prof. T. R. Jones and Dr. Woodward—Devonian Fossils. 387 the casts show ; in some cases, however, the marginal rim is more distinct. : Figs. 4 a—d. These show the cast of a very large and much squeezed carapace (7-5 mm. long; the hollow mould is 8 mm., having more marginal rim behind). The valves have been lengthened and compressed (Figs. 4 6, c), the lobes stretched obliquely, and the curved ventral junction obliterated (Fig. 4a). The results of pressure and the lower scale of magnifying give this specimen an appearance very different from that of Fig. 3. Figs. 5 a, b, show a neat and smaller cast (3 mm. long) of the same species, but modified by pressure (from above downwards and obliquely), so that the length of the valve has been increased, the height lessened, the lobes thrown into an oblique position (as also seen in Fig. 4a), the ventral curve almost obliterated, and by a longitudinal wrinkle or small fold (not well shown in Fig. 5a) the large pyriform lobe is puckered all along its postero-ventral region. The result of these changes is that the modified valve looks almost like a variety of B. Kledeni, M‘Coy; but the evident effects of pressure are all that separate it from the more typical forms, such as Fig. 3. As a new species we propose to call this form Buryricuta DEvontca. As is well known, Prof. Dr. Ferdinand Roemer some years ago noticed a large Beyrichia (about 4 mm. long) from the Devonian rocks of the Bosphorus. See his ‘‘Geognost. Bemerk. auf einer Reise nach Constantinopel,” etc. “« Neues Jahrb.” 1863, p. 521, pl. 5, figs. 8a, b. At p. 509 F. Roemer referred these fossiliferous rocks to the Middle and Upper Devonian; but M. de Verneuil (Bullet. Soe. Géol. France, 2 sér. vol. xxi. (1864), pp. 147-155) regarded them as of Lower Devonian age. In the Grou. Mac. Vol. VIII. (1870), p- 466, Prof. Dr. Ferd. von Hochstetter is cited as referring? them palzontologically to the horizon of the Lower Devonian beds of Western Europe, noting also that they contain some few Upper Silurian fossils. Roemer’s two little figures unfortunately do not allow us to offer an opinion as to the specific characters of his Beyrichia from the Bosphorus. It may or may not be related to our species from Torquay. The new Beyrichia from Devonshire has been alluded to in the Ann. Mag. Nat. Hist. ser. 6, vol. ii. 1888, p. 299, by the Rev. G. F. Whidborne, F.G.S., and is there said to have been found by Mr. T. Roberts, Mr. Solly, and other members of Professor T. McKenny Hughes’s Cambridge party during their visit to Torquay in the ! The Turkish Beyrichie above mentioned are briefly noticed also by Mr. W. R. Swan, in the Quart. Journ. Geol. Soc. vol. xx. (1864), p. 116. * In his Geological Conditions of the Eastern Part of European Turkey, Jahrb. der K.K. geol. Reichsanstalt, vol. xx. 1870. 3 This specimen, collected by M. A. Dumont, was sent to Dr. Ferd. Roemer by M. G. Dewalque, who, having the care of the Museum of the Liége University, has allowed us to see the specimen. It is closely allied to, if not the same as our B. Devonica. 388 R. Lydekker—An Ichthyosaurus paddle. spring of 1888, in the red beds of the “New Cut” or “ Lincombe- Hill Drive,” from which the late Mr. Champernowne obtained his Homalonotus some years ago.' These beds lie high upon the slope of the Ilsham Valley, some hundred yards to the North of Meadfoot Bay. They are considered by Prof. Hughes to be the same as, or, more probably, slightly lower than the Pleurodictyum-beds of Kil- morie; and he has obtained Pleurodictyum and other fossils from beds in their immediate neighbourhood. EXPLANATION OF PLATE XI. Fie. 1. Eehinocaris Whidbornei, sp. nov. Fig. 2. Lchinocaris punctata, Hall; after Beecher, about 2rds.; shown for comparison, and to indicate the form of the whole animal. Fies. 38-5. Beyrichia Devonica. ]].—On an IcurHyosaurian PappLE SHOowING THE CONTOUR OF THE INTEGUMENTS. By R. Lyprxxer, B.A., F.G.S., F.Z.S., ete. N the year 1841 Sir R. Owen described and figured? a slab ot rock from the Lower Lias of Barrow-on-Soar which showed the impressions of the bones and integuments of a pelvic paddle of an Ichthyosaurus, probably referable to the typical I. communis. In this specimen ® it appears that the integuments were produced to a greater extent on the posterior than on the anterior side of the bony framework; and that. while the anterior margin of the soft parts showed evidence of squamation, the larger posterior flap was marked by oblique striz extending from the bones to the periphery which appeared to have been caused by parallel bundles of muscular fibres. The distal extremity of the soft fin terminated in a sharp point far below the distal bones. ’ This specimen appears to be the only English example hitherto described showing the form of the integuments of the paddles. In 1888, however, Dr. E. Fraas published a paper on the integuments of the paddles of Ichthyosaurus,* in which he described two specimens belonging to the Longipinnate®’ group of the genus, which may apparently be referred either to I. acutirostris or the allied I. Zetlandicus. One of these specimens showed both the pectoral and pelvic paddles, while the second only exhibited the pectoral paddle, which is figured in the plate accompanying the memoir. These Specimens confirmed the inferences drawn from the English example, but showed that in the Longipinnate group the integumentary portion of the paddles was relatively wider, and terminated in a blunt lower extremity, which extended but a short distance beyond the distal 1 Grou. Mac. 1888, pp. 487-491, Pl. XIIT.; 1882, pp. 157-8, Pl. IV. Fig. 3. ? Trans. Geol. Soc. ser. 2, vol. vi. pt. i. p. 199, pl. xx. See also Liassic Reptilia (Mon. Pal. Soc.) pt. i. pl. xxviii. fig. 3. 3 British Museum, No. 29672. + Jahresh. Ver. Nat. Wiirttemberg, 1888, pp. 280-303, pl. vii. ° See the writer’s Catalogue of Fossil Reptilia and Amphibia in British Museum, pt. i. p. 69 (1889). R. Lydekker—An Ichthyosaurus paddle. 389 bones. They also showed that the pectoral limb had a broad flap of integument in the axillary region. Oblique striz, like those of the English specimen, were observed on the posterior flap of integu- ment, and were likewise held to be probably formed by muscular bundles; while the squamation of the anterior border of the fin was shown to be of a very minute and fine structure. So far as I know, the above is all the original literature which has appeared on this subject, and I proceed to notice the specimen on which the present communication is based. The specimen in question was kindly sent to me by Mr. Montagu Browne, of the Leicester Museum, who obtained it some time ago from the Lower Liassic quarries at Barrow-on-Soar. It consists of a split slab showing the imperfect thoracic region of a small Ichthyosaur clearly Ventral aspect of the imperfect left pectoral paddle of Ichthyosaurus intermedius ; from the Lower Lias of Barrow-on-Soar. Half nat. size. Aw. humerus; r. radius; «. ulna; 7”. radiale; 7. intermedium ; uw. ulnare; c.c’. centralia. referable to the Latipinnate group of the genus, and apparently belonging to I. intermedius. A large portion of the left pectoral limb is well preserved, the bones having been split in a plane parallel to the dorsal and ventral surfaces; although’ the distal extremity is unfortunately wanting. The half of the slab which best exhibits the paddle is the one in which, if the specimen were not split, we should look upon its ventral aspect; this view being represented in the accompanying woodcut. An inspection of this figure shows that the lateral flaps of integument are clearly marked on the slab, and that their general arrangement is the same as in the specimens previously described. On the narrow anterior flap a minute squamation can be detected with the aid of the 390 Charles Davison — Stone-Rivers, Falkland Islands. lens; while the wider posterior flap shows the oblique lines described by Messrs. Owen and Fraas. These lines are formed by whitish films lying on the rock, which are distinctly striated, and are at first sight very suggestive of fin-rays, although it is on the whole more probable that they really indicate parallel muscular bundles. The axillary region was evidently produced into a well-marked flap, or prominence. In proportion te the bony framework the posterior flap of integument is much narrower than in the specimen figured by Fraas; and since our specimen agrees in this respect with the pelvic paddle figured by Owen, it may be assumed that the distal extremity of the soft part was produced and pointed as in the latter. We have, therefore, now good evidence that while the integuments of the paddles of the two primary groups into which the genus Ichthyosaurus is divided were of the same general type of structure, yet that they differed so markedly in detail as to afford another important point of distinction between the two groups. I may add that Mr. Montagu Browne has been good enough to present the figured half of this interesting specimen to the British Museum. Ji].—On tue Origin or tHe Stone-Rivers oF THE FALKLAND ISLANDS. By Cuartzes Davison, M.A., Mathematical Master at King Edward’s High School, Birmingham. HE stone-rivers of the Falkland Islands have been described by Mr. Darwin, Sir Wyville Thomson, Dr. Coppinger, and other naturalists who have visited those regions.! The accounts given by the two first-named are well-known and easily accessible, and render a full description here unnecessary. But it may not be out of place to summarise the principal features of the stone-rivers, which must find an explanation in any satisfactory theory of their origin. They consist of angular blocks of quartzite, “arranged,” according to Pernéty, ‘‘as if they had been accumulated carelessly to fill the ravines.” The blocks are from two to twenty feet long, and rest “irregularly one upon the other, supported in all positions by the angles and edges of those beneath” (Thomson). At the same time, “they are not thrown together into irregular piles, but are spread out into level sheets or great streams ” (Darwin), the surface of one visited by Dr. Coppinger being “tolerably flat,” and not indicating ‘Ca process of accumulation by flow from either side.” The streams vary in width from a few hundred feet to a mile or more. Their depth is unknown, but, according to Darwin, is probably great: though “far down below, under the stones,” says Sir Wyville Thomson, ‘‘one can hear the stream of water gurgling which 1 A. J. Pernéty, Histoire d’un Voyage aux Isles Malouires, etc. (nouy. éd., 1770, Paris), vol. ii. pp. 1-6; C. Darwin, Journal of Researches, ete. (1879), pp. 196-199; Sir C. Wyv. Thomson, The Movement of the Soileap; Nature (Feb. 22, 1877), vol. xv. pp. 849-360; also, Voyage of the ‘Challenger,’ vol. il. pp. 245-249 ; and the Ene. Brit., art. on the Falkland Islands; Dr. R. W. Coppinger, Cruise of the ‘ Alert’ (1885), pp. 32 33. Charles Davison—Stone- Rivers, Falkland Islands. 391 occupies the axis of the valley; and here and there, where a space between the blocks is unusually large and clear, a quivering reflection is sent back from a stray sunbeam.” The inclination of the surface of the stone-rivers is very small, and this is their most remarkable feature. ‘On the hillsides,” says Darwin, “I have seen them sloping at an angle of ten degrees with the horizon, but in some of the level, broad-bottomed valleys, the inclination is only just sufficient to be clearly perceived.” The actual movement of the blocks does not seem to have been noticed. ‘As far as I can ascertain,” Dr. Coppinger remarks, ‘“‘no attempt has ever been made to estimate the rate of movement (if any) of these ‘runs,’ and there is no evidence whatever of their motion during the present century.” The origin of the blocks themselves has been clearly pointed out by Sir Wyville Thomson. ‘The beds of quartzite are of very different hardness: some are soft, passing into a crumbling sand- stone; while others are so hard as to yield but little to ordinary weathering.” Being worn away unequally, the harder bands project, and at last the joint-formed blocks fall over. The difficulty, however, is to account for their present position and arrangement, and, for this purpose, the following theories have been proposed :— 1. The action of earthquakes, hurling the blocks down the slopes, and then levelling them out into continuous sheets (C. Darwin, A. J. Pernéty). 2. The movement of the soilcap enclosing the stones, the soil being afterwards washed away by the streamlets in the valleys (Sir C. Wyv. Thomson). 3. The former movement of “earth-glaciers,’ which, owing to a change of climate, became desiccated, the earth being afterwards washed away by rain and streams (J. Geikie).’ 4. The action of frost and snow, the alternate freezing and thawing of rain (Sir J. D. Hooker).? 5. The action of glaciers. ‘I believe it will not be difficult to explain their origin in the light of the glacial theory, and I fancy they may turn out to be ground moraines similar to the ‘horse- backs’ of Maine” (J. R. L. Agassiz). 6. The alternate expansion and contraction of the blocks under changes of temperature taking place mainly down the slopes, being assisted by gravity in that direction (C. Davison).* It is not my purpose to discuss these suggestions here; but I may remark that, according to Thomson, ‘ice had no hand whatever in the production of these grand ‘moraines’ of the Falkland Islands.” The second theory has been criticised adversely by Prof. J. Geikie 1 The Movement of the Soilcap: Nature (March 8, 1877), vol. xv. pp. 397-398. * Himalayan Journals (1854), vol. ii. p. 179 (footnote). % Louis Agassiz: His Life and Correspondence, edited by E. C. Agassiz, vol. ii. pp- 694-695. Extract from a letter to Prof. B. Peirce, dated Feb 20,1871. It should be noted that Agassiz’s intention of visiting the Falkland Islands was never carried out. 4 Note on the Movement of Scree-material: Quart. Journ. Geol. Soc. (1888) vol. xliv. pp. 232-237. 392 Charles Davison—Stone-Rivers, Falkland Islands. and Dr. Coppinger with, I believe, conclusive force. With regard to the sixth, though slight movements of this nature must undouht- edly be taking place, they must in this case be unusually small, for the climate of the Falkland Islands is dull and the sky almost continually overcast. Now, in all of the above-mentioned theories, the transport of the quartzite blocks over considerable distances is taken for granted, and the object of the theories is really to account for this transport over a rough and irregular surface, inclined generally at a very small angle to the horizon. But is it not possible that this assumption is unnecessary ; that the blocks, though they have doubtless undergone some movement, still remain in the immediate neighbourhood of the places they occupied before the valleys were formed; that the stone- rivers are, in fact, but an extreme case of the inability of a stream to remove the debris in its course ? On the summits of many of our mountains, we have a phenomenon not unlike the stone-rivers in appearance, and perhaps similar to them in origin. The so-called “blocky structure,” so conspicuous, for example, on Scawfell Pike, occurs in many, if not in most, cases where alternate bands of hard and soft rock crop out at the summit. The softer layers, being more easily weathered, are gradually removed by wind and rain; and, in course of time, the joint-formed blocks of the harder projecting bands fall over in various directions, giving rise to that confused, tumultuous appearance, which seems at first sight to suggest the action of an overwhelming force. The blocks remain almost as they fall, for the forces in action on the mountain-summits are insufficient to displace them greatly. Now, in the Falkland Islands, we have, as we have seen, some- what similar conditions; bands of hard quartzite separated by seams of soft and crumbling sandstone. When streams began to flow over the primitive surface of the country, they bore away, I imagine, the loosened debris of the softer bands, but the resulting blocks of quartzite were too heavy to be moved by them and hard enough to resist atmospheric disintegration. The streams then flowed between and below the blocks, and continued to remove the softer bands beneath, working their way from side to side of the valleys. The quartzite blocks thus gradually subsided vertically all over the valleys, most along the axis and in the lower regions, least at the sides and in the upper parts, forming on the whole a gently sloping surface,” but rough and irregular in its details owing to the different 1 «The temperature is very equable, the average of the two midsummer months being about 47° Fahr., and that of the two winter months 37° Fahr. ‘The sky is almost constantly overcast, and rain falls, mostly in a drizzle and in frequent showers, on about 250 days in the year. The rainfall is not great, only about 20 inches.” Enc. Brit., art. on the Falkland Islands. * It should be noted that the quartzite bands are often much crumpled and distorted, but the surface of the stone-rivers would be fairly smooth in any part, if the total thickness of the quartzite bands formerly above that part were approximately the same all over it. Sir Wyville Thomson states, however, that ‘the general colouring [of the islands] is dark brownish-green, relieved along the strike of the hills by veins of white quartzite denuded by the wearing away of softer rocks on both sides, and left projecting on the mountain-slopes like dilapidated stone dykes” (Ene. Brit.). A. Smith- Woodward—On Rhinobatus Bugesiacus. 393 sizes of the blocks and the various directions of their fall. The surface of the stone-rivers might thus be continuous with the slopes of the surrounding country; there would not necessarily, although there might, be bounding cliffs’ In the “blocky structure” of mountain-summits, a limit in depth must soon be reached, beyond which wind and frost and rain can have but little effect in weather- ing and removing the softer rock. But, in the stone-rivers of the Falklands, the process may be carried very much further: as long as streams are able to find their way among the blocks and can remove the sand between them. This theory seems to me to account satisfactorily for the features of the stone-rivers, so far as they are given in the published narratives. It accounts also for another fact which is not referred to in the theories mentioned above, namely, the proportion of the volume of the quartzite blocks to the volume of the rock that must originally have occupied the valleys. From the slight slope of the surface, and the certainly not small depth, of the stone-rivers, we must infer that this proportion is not inconsiderable. If the for- mation of the stone-rivers, then, began some time after the com- mencement of denudation in the islands, not only must the quartzite blocks resulting from previous erosion in some way have been removed, but the valleys must also have greatly increased in width in order to provide the material for the stone-rivers: a large amount of the softer rock must have been carried away: and, therefore, in part, at least, a cause like that suggested in this paper must have been in action. But if we suppose that the formation of the stone- rivers has all along taken place concurrently with the excavation of the valleys, we can, I think, account for the origin of the former without having to call in the aid of any non-existing agencies to explain the transport of the blocks. 1V.—Nortse on Ra#INOBATUS BUGESIACUS—A SELACHIAN FISH FROM THE LITHOGRAPHIC STONE. By A. SmitH Woopwarp, F.G.S., F.Z.S. INCE 1857,’ the occurrence of a gigantic species of the Selachian family Rhinobatide in the Lithographic Stone of Bavaria has been well known, and three fine specimens are exhibited in the Munich Museum. No figure, however, appeared until 1887, when Dr. K. A. von Zittel published* the illustration he has kindly allowed to be reproduced here; and the only detailed description is that of Wagner,! written about thirty years ago. Quite recently, the British Museum has acquired the counterpart of one of the fossils in the Munich collection—a female individual in a remarkable 1 « Why,’’ asks Dr. Coppinger, ‘‘do they [the stone-rivers} exhibit a margin so sharp and well-defined, yet without the elevated rounded appearance of a river- bank ?’’ 2 A. Wagner, Gelehrte Anz. bay. Akad. Wiss. vol. xliv. (1857), p. 292. 3 Handb. Paleont. vol. i. p. 103, fig. 117. 4 Abh. k. bay. Akad. Wiss. Math.-phys. Cl. vol. ix. (1861), p. 313. 394 A. Smith-Woodward—On Rhinobatus Bugesiacus. Rhinobatus Bugesiacus (Thiolliére ? sp.). Lithographic stone, Eichstatt, Bavaria (after Zittel). (One-twelfth nat. size.) A. Smith- Woodward— On Rhinobatus Bugesiacus. 390, state of preservation; and this is now exhibited in the form of a slab upon the west wall of the Gallery of Fossil Fishes. The specimen in question is complete in all important respects, only the proximal portion of the left pectoral fin and non-essential parts of the median fins being wanting ; but the vertebral column, except towards the extremity of the tail, is shown as fragments or merely in impression, and the jaws are unfortunately buried in the matrix. The fish is exposed from the dorsal aspect, measuring 1:50 m. (about 5 ft.) in total length; and in general form it agrees with the male individual represented in the accompanying figure. The snout is remarkably produced, and on the outer side of each nasal capsule is a long slender forwardly-directed cartilage, evidently to be regarded as prepalatine. The basal pterygia of the right pectoral fin are more clearly shown than those of the Munich fossil, as here figured, the mesopterygium being large and broad, the pro- pterygium long, slender, and segmented distally, and the metaptery- gium somewhat stouter than the latter; the large, very broad cartilaginous fin-rays are also all distinct. The dorsal fins are rela- tively larger than indicated by the outlines in the figure; and the caudal fin has a slightly greater expanse, though this may be due to difference in crushing during fossilization. Coarse rounded sha- green-granules cover the dorsal aspect of the cranium, the pectoral arch, and the longitudinal middle line of the back; but there are no large tubercles or spinous defences. So long ago as 1836, Count Miinster! briefly noticed the caudal extremity of a large Selachian from the Lithographic Stone of Kelheim under the name of Aellopos elongatus; and in 1848, Agassiz? recorded the occurrence of a very large pectoral fin with the pro- visional name of Huryarthra Muensterii. Both these fossils probably pertain to the fish now under discussion, as already suggested by v. Zittel, and, to a certain extent, also by Wagner; but they were not sufficiently described for recognition before 1854, when Thiolliére® gave detailed notes and figures of specimens from the Lithographic Stone of Cirin, Ain, France, identical in every respect, except size, with the Bavarian species. The name proposed by Thiolli¢re— Spathobatis Bugesiacus—is thus applicable to this species; and as there is no significant difference between ‘“ Spathobatis” and the recent Rhinobatus, we prefer to regard the former generic name merely as a synonym of the latter. When studying the Bavarian “ Spathobatis,” Wagner himself distinctly perceived its identity with the French species described by Thiolliére ; but owing to the fact, that the former attained twice the size of the latter, he considered a distinct specific name justifiable, and suggested that of S. mirabilis. According to modern ideas of nomenclature, however, this name must become a synonym; and an examination of the type-specimen of S. morinicus, Sauvage,* from 99 1 Neues Jahrb. 1836, p. 581. 2 Rech. Poiss. Foss. vol. iii. p. 382. 5 Poiss. Foss. Bugey, pt. i. p. 7, pls. i. il. 4 Bull. Soc. Académique Boulogne-sur-Mer, 1873, p. 94. 396 Alfred Harker— Eyes”? of Pyrites in Slate. the Portlandian of the Boulonnais, has convinced the present writer that the last-mentioned name must also share the same fate. Rhinobatus Bugesiacus thus occurs in the Lower Kimmeridgian of Bavaria and §.E. France and in the Lower Portlandian of N.E. France: in the first and last localities it attains its maximum dimen- sions, while in the second it is comparatively dwarfed. The same species may also perhaps be met with in the English Kimmeridgian, but as only detached vertebre have hitherto been discovered, it is at present impossible to arrive at a specific determination. Woopwarpian Muszum Nores. V.—On “Eyres” or Pyrites anp orHerR Minerans IN Snare. By Atrrep Harker, M.A., F.G.S. eee instances of the bodily deformation of rocks by lateral pressure, the case of the phyllade aimantifére of Monthermé is well known. By its strong cleavage this rock gives evidence of considerable lateral compression. Professor Renard? has shown _ that prior to this compression the magnetite crystals already existed in the rock, and were surrounded by a coating of chlorite. The crystals yielded to the pressure much less readily than their matrix, and the latter, having already a firm consistence, became separated from the crystals, carrying the chlorite with it, and was displaced along the planes which are now cleavage-planes, that is, in a direc- tion at right angles to that of the pressure. My object is to show that similar phenomena are not uncommon among cleaved rocks in our own country. Some years ago I obtained from the Penrhyn quarry a specimen of slate with cubes of pyrites, in which the displacement of the matrix around the imbedded crystals is well exhibited. As in ihe French phyllade, the vacant spaces left have been subsequently filled by infiltered quartz, which grew roughly perpendicular to the faces of the crystals. The arrangement is represented in figure 1 (p. 8397). As the “eyes ” are from half an inch to an inch in length, the pyrites, quartz, and chloritic mineral can be easily distinguished with the naked eye, while a thin section makes a pretty object under the microscope (No. 501). In the phyllade aimantifére the magnetite crystals are only 0:2 to 0:8 mm. in length (No. 502). M. Reusch® has noticed a precisely similar disposition of quartz and chlorite around dodeca- hedra of pyrites in a schistose diabase dyke: here too the crystals appear to be only about one-hundredth of an inch in diameter. The phenomenon is probably one of wide occurrence. It is seen in sericitic slates at Blaenau Ffestiniog and at other places in North and South Wales; also in the very pyritiferous slates of Balla- chulish near Oban, The “eyes” are always flattened parallel to ’ Catal. Foss. Fishes, Brit. Mus. pt. 1, p. 83. * Bull. Mus. Roy. Hist. Nat. Belg. vol. ii. p. 134, and plate vi. 1883. See also Gosselet’s “ L’Ardenne,’’ p. 61 and fig. 17, 1888. * Bémmeléen og Karméen, pp. 69, 70, 1888. Alfred Harker—“ Eyes” of Pyrites in Slate. 397 the cleavage-planes and drawn out along the line of cleavage-dip (lonyrain of the French). It indicates that in those cases the pyrites is of very early origin, and that it became coated at an early stage with a chloritic envelope; further, that the rock became thoroughly compacted before it was subjected to the lateral thrust, so that in yielding it was able to leave vacant spaces, which were filled at a later date by crystalline quartz. This last point is proved by the manner in which the quartz has been formed with its crystals perpendicular to the faces of the pyrites. There are, how- ever, other cases in which the quartz has a fibrous structure, the fibres being set parallel to the longrain, that is, to the direction of movement, as diagrammatically shown in fig. 2. This is presum- Sections at right-angles to the cleavage-planes. P=pyrites; Q=quartz; C =chloritic mineral. ably due to the quartz having been deposited concurrently with the process of deformation, so that no vacant space was actually formed. The examples cited by Loretz' from the Thuringerwald must be referred to this kind of action. In these the pyrites has been sub- sequently converted into limonite. Another variety of ‘“‘eye” is found in the Llandeilo slates of Whitesand Bay near St. David’s. Here the whole external surface of the “eyes,” which are about an inch and a half to two inches long, has a strongly fibrous, slickensided aspect. On making a section, it is seen that the pyrites cubes have their angles and quoins rounded off, and little fragments of pyrites are detached and enveloped in the quartz which occupies the corners of the “eyes.” It should be noted that these lenticular or eye-shaped masses are essentially characteristic of discontinuous sliding movement, in which actual disruption has taken place between substances capable of different degrees of yielding, such as the hard pyrites and the less hard rock surrounding it. The same rocks often exhibit the ellip- soidal green spots (distorted spheres) first noticed by Dr. Sorby, which indicate continuous deformation without abrupt slipping. 1 Jahrb. d. kénigl. preuss. geolog. Landes. for 1881, pp. 283-289. 398 Dr. R. Schafer—On Phillipsastreea, @’ Orb. VI.—On PuitiipsastRz4, D’ORB., witH EsprctaL REFERENCE TO PHILLIPSASTREA RADIATA, S.- WOODWARD SP., AND PHILLIPSASTRZA TUBEROSA, M‘Coy, sp. : By Rupotpu ScuArer, Pu.D. (PLATE XII.) NHE genera Phillipsastrea and Smithia have long been a source of trouble to paleontologists, and since the establishment of the latter genus in 1851, it has been very doubtful in which of the two genera certain species of Corals should be placed. The more extended our acquaintance with the species belonging to both genera became, the more probable it seemed that the distinctions between them were in reality unimportant and insufficient to justify a division into two different genera. It was in fact proposed by Kunth as early as 1870 that both genera should be united under the earlier name Phillipsastrea. It has been stated that Phillipsastrea possesses a columella, while Smithia has none; upon the truth of this statement the retention of the two genera depends. Kunth has denied the existence of such a difference. Nevertheless both genera are still retained. From a careful study of the specimens in the British Museum (Natural History) and in the Woodwardian Museum at Cambridge, I have come to the conclusion that Kunth’s opinion is well founded; and in the following remarks I shall further attempt to show that certain species which are still sometimes described as having a true columella do not really possess one. I am indebted to Dr. Henry Woodward, F.R.S., the Keeper of the Geological Department in the British Museum (Natural History), for granting me facilities for the study of the specimens of Phillipsastreea and Smithia under his care, and also for the privilege of having sections made from them, without which their characters could not have been determined. I also owe Professor T. McKenny Hughes my best thanks for his kindness in allowing me to examine the specimens in the Woodwardian Museum at Cambridge. Before giving a description of the specimens in question, a few short notes on the history of both genera might not be without interest. History of the genera.—In the year 1849 d’Orbigny established the genus Phillipsastrea, of which he gave the following diagnosis?: ‘¢ Phillipsastrea, d’Orb., 1847.2 Ce sont des Siderastrea, dont la columelle, au lieu d’étre styliform saillante, est large et divisce en cloisons rayonnantes, comme chez les Columnastrea.” He gives two species :—Phillipsastrea parallela, VOrb., 1847=Astrea parallela, I. A. Roemer, Verst. d. Harzgeb. 1843, p. 5, pl. 3, fig. 1.—Phallip- sastrea Hennahii, dOrb. 1847=Astrea Hennahii, Phillips, 1841. Pal. foss. pl. 6, fig. 16. 1 A. d@Orbigny, Prodrome de Paléontologie, ete. vol. i. p. 107, Paris, 1849. 2 This date is not correct, because though d’Orbigny’s manuscript was ready for publication in the year 1847, as he states in the preface, yet the book was not published until 1849. Dr. R. Schifer—On Phillipsastreea, d Orb. 399 In the year 1850 Messrs. Edwards and Haime’ mentioned the genus Phillipsastrea; the genus Smithia was not established at that date. Their diagnosis of Phillipsastrea contains the words: ‘The centre of the tabule presenting a columellarian tubercle.” As the type species they mention Phillipsastrea Hennahii, Lonsd. (= Astrea — Hennahii, Lonsd., in Geol. Trans., 2nd ser. vol. v. pl. 58, fig. 3). This is of importance, as in the following year this very species became the type of the genus Smithia. In the year 1851 Messrs. Edwards and Haime established the genus Smithia:* “‘ Smithia. Polypier ayant la méme structure que les Acervularia, mais manquant de murailles extérieures distinctes et présentant des rayons septo-costaux plus ou moins confluents,” and (loc. cit. p. 421): ‘“ Pas de columelle.” Type species: Smithia Hennahii (= Astrea Hennahii, Lonsd.), the same species which in 1851 was the type of Phillipsastrea. The following species of Smithia are given: Smithia Hennahii, Lonsd., Smithia Pengellyi, E. & H., Smithia Boloniensis, E. & H., and Smithia Bowerbankii, HK. & H. In the diagnosis of the genus Phillipsastrea we read (Mon. des Polyp. Foss. p. 173): ‘‘ Phillipsastrea. Polypier présentant la méme structure que les Smithia, mais ayant une columelle styliforme,” and (loc. cit. p. 447): “Les Phillipsastrées different des Smithies par la présence de leur columelle.” Type species: Phillipsastrea radiata, S. Woodw. The following additional species are mentioned : Phillipsastrea Vernewili, H. & H., and Phillipsastrea tuberosa, M‘Coy. In the diagnosis of the type species Phillipsastrea radiata (loc. cit. p. 448) we read: “columelle mince et comprimée, en général peu distincte;” the figure (Brit. Foss. Cor. tab. 37, fig. 2) shows no columella. In the description of Phillipsastrea tuberosa, (loc. cit. p. 449) Messrs. Edwards and Haime do not mention any columella, neither does M‘Coy.? Further, the figures given by M‘Coy* do not present, either in the transverse section or on the surface, any indication of a columella. In the diagnosis of Phillips- astraa Verneuili (loc. cit. p. 448) Messrs. Edwards and Haime say: “columelle saillante”; the figure (Mon. des Polyp. Foss. tab. x. fig. 5) shows the same clearly, but only on the surface, since a transverse section is not given. Kunth® has already explained all that has been mentioned so far. He has also given (loc. cit. p. 30, and tab. i. fig. 4) an exact description of Phillipsastrea Hennahit, Lonsd. ( = Smithia ' H. Milne Edwards and J. Haime, A Monograph of the British Fossil Corals, part i. Introduction, p. lxx. Paleontographical Society, vol. ii. London, 1850. 2 H. Milne Edwards et J. Haime, Monographie des Polypiers Fossils des Terrains Paléozoiques, etc., Archives du Muséum d’Histoire Naturelle, tome y. p. 171, Paris, 1851. 3 F. M‘Coy, On some Genera and Species of Paleozoic Corals and Foraminifera, Ann. Mag. Nat. Hist. 2nd ser. vol. 11. p. 124, London, 1849. 4 A Synopsis of the Classification of the British Palzeozoic Rocks, by A. Sedgwick ; with a Systematic Description of the British Paleozoic Fossils in the Geological Museum of the University, Cambridge, by F. M‘Coy, pl. 20, fig. 8, 82. 5 A. Kunth, Beitrage zur Kenntniss fossiler Korallen, Zeitschrift der Deutschen geologischen Gesellschaft, vol. xxii. p. 30, Berlin, 1870. 400 Dr. R. Schifer—On Phillipsastrea, d’ Orb. Hennahii), which contains’ many valuable remarks; especially in- reference to the microscopical structure. In this species the calyx shows ‘a false columella (‘“columellarian tubercle,” as he himself — adds in parenthesis), but the sections show no columella. Kunth, therefore, doubts the correctness of making the presence of a columella a. distinction between the genera Phillipsastrea and Smithia ; moreover, according to Messrs. Edwards and’ Haime, Smithia also has on the tabule a columellarian tubercle, and a Smithia Hennahii and Smithia Bowerbarki they mention “lobes paliformes,” such as might produce a similar ‘structure in the ue to that shown in the fisure of Phillipsastrea Verneuili. Kunth, therefore, arrived at the following conclusion: There is no generic distinction between Phillipsastrea and Smithia so far as ther presence or absence of a columella is concerned; a columella might perhaps be present in Phillipsastrea Verneuili, but in this case it would have to be shown in a section. Consequently the four species separated under the name Smithia by Messrs. Kdwards and Haime must be referred back to Phillipsosires and the name Smithia must be abandoned. In the year 1876 Rominger’ gave a description of Phillipsastrea Verneuili, in which he says: “The centre of the calyx bottom is raised into a columellar knot, and in vertical sections of calcified specimens a central string of greater density can be observed, but it is not a solid axal column; in some species no indication of a columella is perceptible.” Thus it was clearly shown in a section, that the only species about which doubt still existed—Phillips- astrea Vernewli — did not possess a columella. Therefore, Rominger also united the genus Smithia with Phillipsasirga. In the generic diagnosis of Phillipsastrea he says (loc. cit. p. 128): “The longer lamelle unite in the centre and form a pseudo- columellar, nodular protuberance, but do not connect te a con- tinuous vertical axis.’ Since this time, therefore, Lindstrém, C. Ferd. Romer, v. Zittel, and others have united the genera. Mr. James Thomson,’ however who in 1883 desorbed certain species of Phillipsastrea from the Carboniferous rocks of Scotland, - remarks that the species in question possesses a columella. Of Phillipsastrea radiata he says (loc. cit. p. 895): ‘there is a central compressed prominent columella in some coralets,” and further, “ina longitudinal section the tabula [sic] are irregular; some are rect- angular, but the great proportion are bent upwards and meet in the centre and form a more or less discontinuous columella.” His figures, however (loc. cit. pl. iv. fig. 1, 1a, 1b), show no columella, only in one single corallite (pl. iv. fig. 1) four septa are seen to meet. Neither does the longitudinal section show any columella. Of 1 C. Rominger, Geological Survey of Michigan, Lower Peninsula, vol. iii.; part ii. Paleontology, Corals, p. 128, pl. 23, fig. 2, New York, 1876. 2 J. Thomson, On the Development. and Generic Relations of the Corals of the Carboniferous System of Scotland, Proc. Phil. Soc. Glasgow, vol. xiv. p. 394, Glasgow, 1883. fess Geol. Mag 1689. Decadelll VoIVIPLX1. Berjeau & Highley.lith West Newman & Co.imp Philipsastraea radiata. S.Woodw. sp. Dr. R. Schifer—On Phillipsastrea, @ Orb. 401 Phillipsastrea tuberosa he says (loc. cit. p. 896) “the corallum is mammillated, and there is a stout laterally-pressed columella.” It is evident that, if Mr. Thomson were correct in stating that Phillipsastrea radiata and Phillipsastrea tuberosa really possessed a columella, then the union of Phillipsastrea and Smithia, as proposed by Kunth and accepted by subsequent writers, would be incorrect ; on the contrary, both genera would have to be maintained in the sense in which they were proposed by Messrs. Edwards and Haime. It therefore appeared to me desirable to re-examine the original specimens of M‘Coy and of Messrs. Edwards and Haime, which are contained in the Woodwardian Museum at Cambridge, as also the specimens in the British Museum (Nat. Hist.), to ascertain whether they possessed a columella or no. Below I give a short description of the specimens, together with the results of the observations I was - able to make. PHILLIPSASTRHA RADIATA, 8. Woodw. sp. (Tubipora radiata, S. Woodw., Syn. Table of Brit. Organic Remains, p. 5, 1830). Spec. Char.—Corallum massive, composite, forming irregular broad astreiform masses. Distance from centre to centre of the calices from 5mm. to 12mm. Diameter of the calicular axial fossa from 2mm. to 38mm. ‘The circumference of the calicular fossa raised in a slightly prominent rim. The inclination of the inner surface of this calicular fossa almost perpendicular. Depth of the calicular fossa about Imm. Septa thin, 22-30, and confluent with those of the neighbouring calices. Septa alternately longer and shorter; of the longer septa two or more opposite ones meet and thus form in the calicular fossa a transverse ridge, which sometimes is joined by other septa. The shorter septa reach only a very short way into the calicular fossa. Vesicular tissue is plenti- fully developed between the septa. It consists of hollow, semi- cylindrical vesicles, the concave side downwards, axis of the semi- cylinders perpendicular to the septa. In close proximity to the calicular fossa the vesicles are somewhat smaller, more closely set, and the concave side is here turned downwards and outwards. In the inner part of the corallite tabule are developed; these are mostly horizontal, still they occasionally bend upwards in the middle and thus assume the form of an obtuse cone with its apex uppermost. Observations and Remarks.—It is known that this species was proposed by Messrs. Hdwards and Haime for certain Corals, described by M‘Coy partly as Sarcinula placenta, partly as Sarcinula Phillipsi. The specimens in the Cambridge Museum were the type specimens of Edwards and Haime, these being also the original specimens of M‘Coy. During my visit to Cambridge I had the opportunity of studying them. They agree in so many points that Edwards and Haime appear to have had very good ground for classing them as one species. The specimen described and figured by M‘Coy as Sarcinula placenta shows somewhat smaller dimensions than that which he describes as Sarcinula Phillipsi. Moreover, when M‘Coy states that in. Sarcinula placenta the tabule are more horizontal, DECADE III.—VOL. VI.—NO. IX, 26 402 Dr. R. Schifer—On Phillipsastrea, a’ Orb. ; whilst those in Sarcinula Phillipsi are cone-shaped and bent upwards, he is perfectly correct. To this question I shall recur later on, but I would here remark that no distinction of species can be based on this difference of tabule, since the two species are connected by individuals showing numerous intermediate gradations. Arrangement of the septa.—As already mentioned two or more opposite septa in each calyx meet and form a kind. of ridge, which other septa join. In this way are produced configurations in the calicular fossa, which, it must be admitted, sometimes closely resemble a columella. This resemblance however is merely super- ficial; closer observation with the lens shows that the septa only meet. On p. 403, Figs. 1-8 I give enlarged figures of the middle parts of some corallites from one of the type specimens of Phillips- astrea radiata, HK. & H. (type of Sarcinula Phiilipsi, M‘Coy), which I was able to prepare at the Museum in Cambridge. The type specimen of M‘Coy’s Sarcinula placenta does not show on the surface that septa join inside the calicular fossa; but this I believe is only owing to the imperfect state of preservation. There are however in the British Museum (Nat. Hist.), as also in the Cambridge Museum, other specimens, some of which do actually show configu- rations which appear to be columelle. But this is not always the case, as I have already pointed out, and neither the figure given by Phillips,’ nor that given by M‘Coy,” to which Edwards and Haime refer in their description of the species, nor that which they them- selves give,? shows a columella. Thomson’s fig. 1, pl. iv. shows only in one single corallite a junction of four septa. The question, however, whether Phillipsastrea radiata has or has not a true columella can only be decided by sections. The only three sections, which have hitherto been figured * show nothing conclusive. New sections were prepared. It was impossible to make sections of the — typical specimens in the Museum at Cambridge without destroying those parts figured by M‘Coy. Accordingly, sections of unfigured specimens in the British Museum and in my own collection were prepared. ‘The said specimens exactly corresponded in all essential characteristics with the type specimens. In consequence of this I was able to examine four horizontal and six vertical sections of four different specimens which were found in the Carboniferous Limestone at Haford-y-Calch near Corwen, North Wales, and in the Avon section, near Bristol. In horizontal section the calices show the same phenomenon as is sometimes observed, although not so clearly, on the surface of the corallum. I was not able to identify in the specimens before me that bilaterally-symmetrical arrangement of the septa, which ac- cording to Kunth’s researches forms so distinctive a characteristic of 1 J. Phillips, Paleozoic Fossils of Cornwall, Devon and West Somerset, pl. vii. fig. 15p, London, 1841. 2 M‘Coy, Brit. Pal. Foss. pl. iii.n, figs. 9, 9a, 94. 3 Milne Edwards and J. Haime, Brit. Foss. Cor. pl. 37, fig. 2. 4 M‘Coy, Brit. Pal. Foss. pl. 38, figs. 9¢, 94.—M. Edwards and J, Haime, Brit. Foss. Cor. pl. 37, fig. 22.—J. Thomson, loc. cit. pl. iv. figs. 1, la, Fics. 1, 2, 3. Outline of calices of type-specimen of Phillipsastrea radiata, S. Woodw. sp. (= Sarcenula Phillipsi, McCoy). Fics. 4, 5, 6. Type of Phillipsastrea tuberosa, McCoy (= Sarcinula tuberosa, McCoy). 404 Dr. R. Schafer—On Phillipsastrea, d’ Orb. the Zetracorallia. The reason of this may be that the arrangement above mentioned is shown usually only in young Corals. Kunth* himself could not distinguish the bilaterally-symmetrical arrangement of the septa in the genus Phillipsastrea, but could distinguish it clearly enough in the closely-related genus Acervularia. Under these circumstances I must refrain from indulging in any speculation as to the position of the “ Haupiseptum,” the “ Gegenseptum” and the «« Nebensepta,” and confine myself solely to giving a description of those relations which I really observed. All the corallites in the sections show two kinds of septa; when regularly and normally developed, 12 longer septa and 12 shorter alternating seemed to be the number. Such regularity in the development I could not, however, observe in every case; in most cases more than 24 septa were present, and here and there two of the shorter septa came between two of the longer, and often some of the longer septa were shortened and could hardly be distinguished from the shorter. The sections (see Pl. XII. Figs. 3-7) show clearly that in most cases two or more opposite septa unite and form a con- tinuous line, which traverses the whole corallite. In the central part this line is often somewhat thicker ; it isin some cases joined by others of the longer septa. No columella is seen in any of the corallites, either in the horizontal or in the vertical sections. The vertical section of two neighbouring corallites of the hest preserved specimen, Pl. XII. Fig. 4, cuts exactly the vertical axis of the latter, only the upper part of the section (owing to an accident of growth) is slightly excentric, that is to say, intersects the imaginary axis of the corallite at a very acute angle. Accordingly the upper part of the figure shows the section of two neighbouring septa, but further down, where the section runs through the central axis, it intersects the point where two neighbouring septa join, and the lower part of the figure shows but one septum line; here these two septa are joined together. The four other vertical sections which I examined agree with this in every particular of importance— a columella is nowhere to be observed. Wall.—On the upper surface of the coral no wall can be perceived, but the distal ends of the septa of the neighbouring corallites appear to run into one another. Nevertheless some indication of a wall may be perceived here and there in that the septa in some places are not altogether confluent, but the line of apparent junction is broken, and so suggests the place where a wall might be. Neither is any wall perceptible in the horizontal sections of Phillipsastrea radiata. When more highly magnified however, one often sees that the septa of neighbouring corallites are not really confluent, but that they overlap each other and are separated by a small space. Sometimes indeed, but very rarely, the septa do run together in a continuous line. It is worthy of notice that a so-called interior wall unquestionably does not exist. It was formerly generally supposed that in all 1 A. Kunth, Das Wachsthumsgesetz der Zoantharia rugosa, etc., Zeitschrift der Deutschen geologischen Gesellschaft, vol. xxi, p. 659, Berlin, 1869. Dr. R. Schifer—On Phillipsastrea, d’ Orb. 405 species of Phillipsastrea the proper wall was wanting, but that an interior mural investment existed, the presence of which was looked upon as a generic character. This view, however, certainly does not hold good in the case of those species examined by me. Only in very rare cases, in single corallites, could I perceive near the outer part of the central cavity anything that would suggest the rudiments of a wall between the septa. These rudiments show in horizontal sections the same arrangement as the vesicles, but differ from the latter in that they have the same structure as the septa. These rudiments of an interior wall are only of very limited extent, they comprise at the most only one-eighth of the circumference of the calicular fossa, and are besides so seldom met with, that they appear to be unimportant for purposes of classification, and I consider them rather as abnormal structure. PI. XII. Fig. 7 shows a corallite in which such rudiments occur. In the same way Schliiter and Barrois have disproved the existence of an interior wall in certain species of Acervularia. Endothecal sclerenchyma.—The endothecal sclerenchyma which fills up the interseptal loculi consists of semicylindrical vesicles with their concave side turned downwards, which lie above one another in alternating rows. This arrangement is substantially the same as that of Phillipsastrea Hennahii, the internal structure of which has been described by Kunth. To illustrate the structure he has very aptly likened the arrangement of the vesicular tissue to that of “semicircular drain-tiles.”’ The figure which he gives (loe. cit. p. 33) will also facilitate the comprehension of the structure of Phillipsastrea radiata. In the inner part of the calyx, where the vesicles surround the central cavity, they are closer and more perpendicularly arranged, whilst in the outer parts of the calyx the vesicles are coarser and flatter (Pl. XII. Fig. 4). Itis nevertheless difficult to see whether the different forms of vesicles really represent a different structure, or whether it is merely due to the difference of angle at which the section cuts the axis of the semicylinder. a3 crispus. Prof. G. H. Stone—Stones of the Salt Range. 415 In short all our graptolitic zones except the insignificant and probably local zone of Monograptus argenteus occur here. Before finally quitting the representatives of the Stockdale Shales, a word concerning the Nereites beds is necessary. These have been referred to the Diewenhany, and possibly forms like Nereites occur in the Devonian beds, but the specimens which Herr Glass collected at Bad Steben are so exactly like the Gala ones, both with reference to the lithological character of the containing rock, and the nature of the fossils, that I cannot help believing that they are of that age. The Wenlock shales with Cyrtograptus Murchisoni are represented in Herr Glass’s collection by specimens from Hinzelnhofen, with Monograptus vomerinus, Cyrtograptus, sp., Cyrto.? spiralis, and in the Dresden Museum by a specimen from Linda with Monograptus priodon, M. vomerinus, Cyrtograptus, sp., C.? spiralis, Retiolites Geinitzianus. Above these shales lies the Ockerkalk with Cardiola interrupta, etc., and like the Cardiola beds of Sweden and the Lower Coldwell beds of Westmorland separating the Cyrtograptus beds from the beds with Monograptus colonus. The latter are found at Gunzenberg near Plauen with Monograptus Remeri, and at Grafenwarth near Schleiz with Monograptus colonus and M bohemicus. Lastly, the Tentaculiten-knollenkalk with Pterniea subfalcata, P. retroflexa, etc., appears to represent the Upper Ludlow beds of Britain, and the limestone of H. 2 in Bohemia. Beds of higher age, such as the Styliola beds and Goniatite lime- stones are probably comparable with higher stages of the Bohemian basin, which they altogether resemble, thus yielding additional evidence of the accuracy of Prof. Kayser’s view as to the age of stages FT, G, and H. As I understand that Herr Frech has visited the Hof district in order to examine these Devonian rocks, further discussion is rendered unnecessary. The result of the cursory examination of the area has been to show that the difference hetween the Bohemian and Bavarian beds is by no means great, where beds of the same age can be compared, and that even our British deposits are in many cases represented by many similar strata in Bavaria, and the Thiiringerwald; that this is specially the case with the graptolite-bearing shales and adds one more instance to those which have been adduced to prove the value of these forms in marking stratigraphical horizons. IX.—On tHe ScratcHep AnD Facrettep Stones or THE Sat Ranee, Inpta. By Professor Grorcre H. Stonz. T the Meeting of the British Association in 1886, a facetted and striated pebble from the Salt Range, Punjab, was exhibited and described, by A. B. Wynne, F.G.S. Another and larger one was presented by Dr. W. T. Blanford, F.R.8." 1 Grou. Mag, 1886, Dec. III. Vol. III. pp. 492, 494, and p. 574. 416 Prof. G. H. Stone—Stones of the Salt Range. During the discussion that ensued, the question was considered whether the stones had received their shapes from the action of wind- blown sand. Having made a special study of sand-carving in a favourable region, the writer became interested in the subject, and with a view to compare the Punjab stones with the sand-facetted rock- fragments so common in various parts of America, wrote to Dr. Blan- ford in order to obtain specimens of the stones in question. By the kindness of Dr. Blanford and Mr. Wynne, plaster casts of both the specimens described by them have been sent to me. Dr. Blanford also put me into communication with Dr. Henry Warth, who has kindly sent me three of the scratched stones which he had found in the field. It is the object of the present paper not to enter upon the large question of a Glacial period in Paleozoic or Mesozoic time, but briefly to consider the testimony of the specimens about to be described as to their own origin. Most of the conclusions arrived at have been anticipated by those who have discussed the origin of the shapes of these particular specimens.’ Yet conclusions drawn from observations made in widely removed regions have a comparative value; therefore, at the risk of repeating what has been observed elsewhere, the facts are here recorded which, observed in Colorado and Maine, throw light on the origin of the markings on the stones in question. The existence of a Glacial period can only be proved by the whole mass of field evidence, and this can only be worked out by the geologists on the ground. In solving the general problem it will be necessary first of all to deter- mine the manner in which the stones and boulders were facetted and scratched. Afterwards comes the question how they were brought to their present positions in the midst of clay or sand. LHvidently a study of the markings on the stones can afford little direct evidence except on the first of these questions. The specimens in my possession are the following. No. 1. This is a plaster cast of the stone exhibited before the British Association by Mr. Wynne. The form is not that which would be caused by the wind. No. 2. A plaster cast of the stone described by Dr. Blanford. The cast, Dr. Blanford informs me by letter, does not show the scratches as plainly as the original. Yet the scratches on the facets are so readily distinguished that a friend, a mining engineer, who happened to be present when the cast was received, at once exclaimed: “« Why it looks as if it had been in a Mexican arastra.”’ The scratches are not such as could be produced by blowing sand or gravel. No. 3. Forwarded to me from Stuttgart by direction of Dr. Warth. It is composed of a dark red felsitic ground-mass, containing many crystals and grains of a lighter red felspar, with some free quartz and small quantities of one or more accessory minerals. All fracture surfaces of the stone are quite uneven. On breaking off a portion 1 Including in addition to the original articles of Dr. Blanford and Mr. Wynne, communications by Mr. R. D. Oldham, Grou. Mae. Jan. 1887, and from Rev. A. Irving, Grou. Mac. April, 1887. Similar specimens are discussed by Dr. H. Warth, Records Geol. Survey of India, vol. xxi, pt. 1, 1888. Prof. G. H. Stone—Stones of the Salt Range. 417 of the stone the fresh surface was seen to be of a lighter and more rosy colour than the original surface. The felspar grains and crystals of the surface are perceptibly roughened. The stone is thus proved to be weathered, though the discoloured layer is quite thin. The composition and structure of the porphyry indicate that it is a very enduring rock. The striated surfaces, even at the bottom of the broader scratches, are apparently as much weathered as the rest of the stone. There are four principal planed facets, and their sides are nearly parallel like those of the faces of a prism. One face is nearly plane, the others have a curved or broken-curved cross- section. The facets have been reduced to an even surface and afford a marked contrast to the rough fracture surfaces. The scratches are quite straight and distinct, though their sides are not so sharply defined as is usual on recently facetted stones. The whole outer surface has received a fine polish, such that the apices of the larger projections have been rounded and the smaller ones nearly erased. The stone is three inches and three-quarters in length, and its greatest transverse diameter is two inches and three-quarters. The angles between the facets are not sharp, partly in consequence of the fine polish before described, and partly because the planed surfaces do not in general meet, but are separated by a narrow strip of unplaned surface retaining the uneven form due to fracture, except as it has been modified by the fine polish before mentioned. No. 4. Sent to me direct from India by courtesy of a returning missionary. Diameters, two inches and an eighth to three inches and a half. It is composed of a light red porphyry. Most of the larger grains and imperfect crystals of felspar which are exposed on the planed facets have weathered so as to be quite rough. There are a number of small irregular depressions on the planed faces caused by the partial weathering of the less resistant grains. The smooth facets are arranged about an axis roughly after the manner of the faces of a prism, and one end of the imperfect prism thus formed is also planed. The remainder of the surface is uneven, and is simply a fracture-surface modified by a fine polish, which has removed the apices of the angles and the smallest of the projecting points. Some of the faces do not show distinct scratches, though planed to a flat and even surface. The surface of this specimen has been more modified by weathering than No. 8. The weathering involves the bottom of the scratches as well as the unscratched surfaces, and there is little, if any, difference in the depth of the weathering in different parts of the stone. No. 5. Also sent direct from India. It is about three inches long. It is a fragment recently broken off from a water-rounded cobble that was probably about six inches in diameter. It is composed of compact, fine-grained quartzite, which here and there contains microscopic grains of felspar. One portion of the cobble has been distinctly planed and scratched. At least one quarter of an inch has been ground away from the stone, if we estimate its original shape from the curves of the rounded portion of the stone adjacent to the planed facet. The scratched surface presents gentle undulations DECADE III.—VOL. VI.—NO. IX. 27 418 Prof. G. H. Stone—Stones of the Salt Range. both parallel to the scratches and transverse to them. Particular scratches or grooves can be traced for two or three inches across the whole facet, though in general the smaller scratches are not so distinct as those on the porphyry, and they often become confluent. On the planed facet some of the felspar grains preserve their polish, except at the edges ; others are weathered so as to be uneven, as also are those on the rounded portion of the stone. This specimen shows less weathering than Numbers 3 and 4. CAUSE OF THE STRIATION AND F'ACETTING. _ First.—Al1I who have seen the stones agree that they have a genuine and ancient look. They have either been weathered since they were scratched, or the surface has been treated with corrosive acids not found in the field. The number of places where they have been found is inconsistent with such an accident. Most of the scratches are too straight and parallel, also too broad and deep to have been made by the unassisted hand. The scratches on No. 5 might perhaps have been made in such a machine as the arastra. The facets on the others might be produced on a grindstone if the stones were held very firmly. The stones resemble no stone implement, and are not. fashioned for use. If ground by man, it must have been for purposes of deception or for grinding something else. In either case it could not have been the act of a Paleolithic man, but of one furnished with modern machinery. The evidence of the stones points to their having been ground and striated a very long time ago. Their testimony thus unites with the field evidence as to the distribution: of the stones over wide areas, their situations on the tops of moun- tains, often remote from places likely to have been inhabited, their being found independently by several different observers, their being associated with the outcrops of certain boulder-beds, etc., to prove that the stones were not the work of man. Second.—Some, perhaps all, of the specimens have been subjected to a limited amount of polishing since they were facetted. The larger inequalities of the fracture-surfaces remain, yet the surface of both the projections and the shallower hollows has been distinctly smoothed. ‘This is of the same sort as would result from a very limited amount of water-wear, also that resulting from soilcap movement. For instance, in the Rocky Mountains the miners’ “float rock”? is often found from one-fourth of a mile up to one mile or more from the parent vein. Reference is made not to the stones transported by running water, but to those of the talus or angular gravel which covers the slopes of a large portion of the mountains. This mass of disintegrated rock is a sort of mineral glacier slowly sliding down the mountains, and even the hard vein quartz is usually perceptibly smoothed by the attrition of the earth and stones with which it has come in contact during its journey. The same sort of polish is not seldom found on the harder fragments situated on the talus at the base of a scarp of erosion of sedimentary rock. During the disintegration of the boulder-bed of the Olive group such friction would have helped to smooth the stones in ques- Prof. G. H. Stone—Stones of the Salt Range. 419 tion, as has been suggested by several of the writers on this subject. Here in the Rocky Mountains there are fine facilities for studying soilcap movement, and without exception the instances of it observed by me show only a limited amount of polishing, the apices of the. angles being rounded and the surface smoothed without being reduced to a plane like the facets of the Punjab specimens. The soileap polish is substantially like that which the facetted stones have received since they were facetted. But I have never found, on any piece of float-rock, scratching that in kind or degree resembled the planed and striated facets of the stones under discussion. There is a satisfactory reason for this. The slowness of soilcap movement gives time for the stones to accommodate themselves partially to each other’s movements. If the friction were to become great enough to produce such wide and deep scratches as appear on the planed facets of the stones in question, they would partly roll past each other rather than slide. It seems to be certain that the “olaciated’’ stones have been polished since they were scratched, and this fine polish could be caused by soileap movement or by a limited amount of water- wear, Third.—The formation of distinct scratches constitutes a problem distinct from that of the planing to an even surface. Could the scratches have been formed by wind-blown sand or gravel ? Scratches may be made, first, by a point rubbing against a surface and being held in the same relative position towards it; second, by a rolling body crushing its way into a softer or more brittle surface ; third, both these processes may combine to produce the scratches. It is evident that grinding by the use of loose powders involves the second and third of these processes, while planing and the use of grindstones involve the first, and produce scratches having an even and sharply-defined margin. Grains of sand and gravel stones when impelled by the wind or by moving water have a rolling as well as a sliding motion. This I know to be the fact from observation, though it is easy to prove that this must be the natural mechanical result of friction applied to one side of a moving solid that is surrounded by a liquid or a gas. As a body of irregular shape, like grains of sand and gravel stones, rolls, or partly rolls, partly slides upon another body, new points of the moving body are continually brought into contact with the stationary body, and since the shape is irregular, the new point of contact will usually be situated to one side of the original point, and the track of the grain will necessarily be crooked. If an irregular grain be impelled in a straight line, it cannot often preserve its direction in the same vertical plane after rebounding, for the friction will be applied to one side of the vertical plane in which is situated the centre of gravity of the body, and the grain will be thrown obliquely sideways. So, too, air and water are constantly being thrown into vortices by the inequalities of the surfaces over which they move. For these reasons it must seldom, if ever, happen that wind or water can impel sand or gravel with the steady motion required in order to produce long straight scratches. The larger stones often produce 420 Prof. G. H. Stone—Stones of the Salt Range. scratches that can be distinguished by the unassisted eye, but they are seldom more than a small fraction of an inch in length. Here, in the Rocky Mountains, the finer dust broadens these larger scratches more . than it deepens them, so that they are soon obliterated or changed to shallow grooves. Stones one-fourth to half an inch in diameter are frequently transported by the winter winds, and the flying gravel is sometimes so painful that hcrses cannot be made to face it, and I know of a blue eye-shade that was broken by gravel while the wearer was facing a Chinook wind in Colorado. Now the scratches of these Salt Range stones have sharply-defined borders, and they are two inches or somewhat less in length, and most of them very straight. The graving tools that produced them moved with a very steady motion, and the depth is such, that a considerable force was required. The hypothesis that under any conditions blowing sand or gravel could produce such scratches may once for all be confidently rejected. Fourth.—Assuming that the scratching could not be caused by wind action, could the facetting be so caused ? We may classify with sufficient accuracy for our present purpose the conditions under which facetting is done by the wind as follows. First, where the upper surface of a stone only a few inches in diameter lies nearly on the same level as the surface of the soil or of other stones around it. The small stone often has its upper surface ground away to near the level of the adjacent earth, and often has its form determined by the shape of the adjoining bodies. It is surprising how flat many of these small facets are, especially when the stone is homogeneous in composition. Examina- tion of many facets shows a tendency to form a gently undulating surface, the crests of the low undulations more often being transverse to the direction of the wind and an inch or more apart. In the class under consideration the stone is so small, and is so far protected by the adjacent bodies, that a large part of the carving is done by flying grains as they first strike the stone. at which time their motion had been in great measure determined by the adjacent land surface. If in any way one of these small stones becomes overturned, a new facet may be formed in the same manner. A somewhat different case is presented when a stone or boulder projects considerably above the ground, or has a large and nearly horizontal surface near the ground. In this case a much larger proportion of the grinding is done after the blowing stones have once rebounded from the fixed stone. The rhythmical friction of the wind against the fixed stone and the repeated reboundings in this case determine the character of the carving more than the direction of original impact. The sand-carved surface under these circumstances is usually covered by shallow grooves parallel with the direction of the prevailing wind. This form of carving appears to be related to the oblique reboundings of the grains sidewise. The grooves are an inch or less in breadth and seldom more than the sixteenth of an inch in depth. The difference between the two Prof. G. H. Stone—Stones of the Salt Range. 421 forms of sand-carving may be illustrated by sea-waves and true water undulations. In the undulations the crests are convex above, in the wind waves they are bounded by two concave surfaces meeting in a somewhat blunt angle. But the undulations of the sand-carved surfaces are more often transverse to the wind like ripple-marks, while the concave grooves are parallel to it. The two forms are often superposed, so that a large number of the concave grooves can not seldom be traced up and over a long transverse undulation, or they give rise to a large number of conchoidal depressions. Where the stones project considerably above the ground, several faces are usually being polished simultaneously or as the wind changes. At the base of the Rockies the plains are strewn with multitudes of granite-drift boulders from the mountains. One can hardly go a hundred feet on these plains without finding boulders presenting polished facets in all positions with respect to both vertical and horizontal planes. A single boulder may have a dozen or more facets, just as if one could polish up the Matterhorn, leaving its arrétes as so many facet-angles extending downward and outward in all directions. The angles between adjacent facets are terminated by rather short convex curves, so that they are somewhat rounded, not true mineralogical angles. The grooves often have different directions on different faces; but in places where the wind can only act when blowing in a certain direction, they are parallel. They can often be traced up to a facet angle and around on to the next facet, especially when the angle is quite obtuse. Grooves can be found at all angles to facet edges, both parallel and transverse to them. The positions of the facets of a given stone are evidently determined partly by the original shape of the stone and partly by the accidents of the grinding process. The facts in Colorado abundantly prove that several facets can be formed contemporaneously, and that it is not necessary in all cases to premise a change of position of the stone when more than one facet is found. These observations, especially those relating to the angles which the conchoidal grooves make with the facet edges, differ from those of Mr. Oldham. This perhaps may be due to the wind being more constant in direction in India than in Colorado. Here the prevailing direction of the grooves is north-west, but sand and gravel are transported by winds from the north, west, and sometimes from the south or south-west. The conclusion follows that the facetting of the Punjab specimens might be simulated by wind action, but not the flat, almost plane surfaces of the facets. Fifth. Were the scratching and facetting done by glacier-ice ? This is the opinion of Messrs. Blanford, Oldham, and Wynne ; but the Rev. A. Irving objects (loc. cit.) that during extensive observations in the Alps, he has not seen stones facetted like these. The writer has carefully examined the moraines of the local glaciers of the White Mountains in New Hampshire, also those of the Rocky Mountains, and never has found stones facetted im so many planes as the stones in question. In this respect my obser- vations exactly accord with those of Mr. Irving. But in the lower 429 LYOF: G. H. Stone—Stones of the Salt Range. portion of the till of Maine there are literally multitudes of stones glaciated on all sides and often in flat facets like the specimens under discussion. American geologists are now nearly unanimously in accord with the Swedish geologists Torell and Holst that the _ lower part of the till of New England was a ground moraine beneath an ice-sheet, while much morainal matter was distributed through the lower part of the ice. The stones under this deep sheet of ice were much more intensely glaciated than in the case of the shallower valley glaciers. It is not needful now to go into the discussion of the molecular physics of glaciers. If it be affirmed that glacier ice is too fluid (or plastic) to hold stones long enough and firmly enough to permit them to be facetted and violently scratched, the matter can be decided by an appeal to the ground moraine of the New England ice-sheet. The only way to escape the conclusion that land-ice can scratch and facet stones like the Punjab specimens is by denying that New England was covered with land-ice. But the hypothesis of the glacier origin of the till of New England was never more strongly entrenched than at present. Every year since the days of Agassiz has brought new confirmation. The terminal moraines, the osar marking, the courses of the long glacier rivers, and all the other marks of land-ice, constitute over- whelming proofs of the reality of that ice-sheet. I conclude that both the facetting and the striation of the speci- mens under review are of the same kind that in geological time past have been wrought by glacier-ice of considerable thickness. Sixth.—Could the scratching and facetting have been produced during a landslip? No observations of stones being planed during a landslip have been recorded in America so far as I know. Yet it is extremely improbable that a landslip could occur without attrition of the stones involved. The flames seen at the great slip at Goldau indicate an evolution of molecular heat that could only be caused by great friction resulting in a large amount of crushed rock. During the land-slip the motion is so rapid that the stones would not have much time to roll into new positions ; yet where so much work is being done, it is difficult to place a limit to the kind of work we can admit as probable. While, then, no evidence is offered to the effect that direct observation shows that stones such as the Salt Range specimens have been scratched and ground to flat facets during land- slips, yet when we consider the forces involved and the great energy of action, it appears highly probable that landslips might produce such a kind of work. The scratching has plainly not been produced by a modern landslip, unless in the case of specimen No. 5. The weathered condition of the facets proves that the scratching was done before the deposition of the specimens in the boulder-bed, or simultaneously with it. On the whole I see no cause afforded by the facts now known sufficient to warrant denying that such forms as those under dis- cussion might be produced during landslips of large masses for a considerable distance. Seventh.—Could the scratchings be produced by fault-movements ? Prof. G. H. Stone— Stones of the Salt Range. 423. In several cases I have found in the fault-breccia stones that had been scratched, though none of them were facetted in so many planes as these. In the movements of faulted rocks we certainly have an agency capable of a steady motion and powerful enough to plane the hardest rocks. The facets of these specimens are not so smooth as ordinary slickensides on large masses of rock. Most of these scratches were made by graving tools not yet dulled by long friction. No. 5 may have been produced by a recent fault, the others must have been striated before deposition. The hypothesis that these stones were once a part of the fault-breecia would postulate faults occurring before the deposition of the boulder-bed, a portion of the breccia becoming in time exposed on the surface by the decay of the rock on each side of the fault, and the stones subsequently being carried by some means into the boulder-bed. There is much here _ that is unknown, yet every hypothesis that alleges a cause sufficient for the required work is entitled to a hearing and a fair decision according to the whole evidence. Eighth.—Were the markings caused by floating-ice? Mr. Oldham (loc. cit.) well sets forth the uncertainties regarding the work of ice- floes or bergs upon the stones contained within them. No one seems to have seen shore-ice or any other form of floating-ice facetting stones like the Salt Range specimens. The writer has visited several places on the coast of Maine where ice-floes had been driven ashore with such force as to pile up blocks of ice to the depth of ten to twenty feet. The shore was left strewn with stones and even large boulders four to six feet in diameter. The scratches on the stones were very irregular, in no way resembling those of the stones under discussion. The shore-ice during the rise and fall of the tides produces on the coast of Maine no such markings and planing. Bergs and thick floes would be less easily broken into blocks and might have greater power to facet stones than the shore-ice of Maine. In the present state of the argument floating-ice must be regarded as one of the possible agencies for facetting stones, yet one concerning which little is positively known. River-ice, especially at the time of the breaking of an ice gorge, is here included under the term floating-ice. The expansion of lake and river-ice produces scratches on the stones of the beach, but no such regular striation and facetting as that under consideration, and large stones driven swiftly along by water can be scratched, but not in a way like these. The only natural agencies that seem to be adequate to produce such straight scratches and such flat facets as those of the Salt Range stones that have occurred to me are glacier- and floating-ice, land- slips, and fault-movements; and concerning three of these agencies but little is known by direct observation. They must, however, be adequately considered before the theory of glacier-ice can be regarded as fully established, though the glacial hypothesis is not inconsistent with our supposing that part of the stones were formed in some other way than by glacier-ice. In the absence of direct observation of the stones involved in landslips, fault- 424 Prof. G. H. Stone—Stones of the Salt Range. movements and floating-ice, no test can be named whereby to dis- tinguish stones scratched in these ways from those of the glacier. In other words, in the present state of the argument, the scratching and facetting of the stones do not reveal their origin with certainty. Until proper tests are devised, we must rely on the general field evidence. Some progress can, however, be reported, for the facts certainly prove that the Salt Range specimens are not due to wind or water action. This narrows the field of future research some- what. It is desirable that observations of the stones involved in the other processes named should be studied as carefully as those of the glacier have been. It will be noted that the above stated conclusions are based solely on the nature of the markings on the specimens. These specimens are all the material I have for an inductive argument. The general argument in several ways will enable us to distinguish to some extent between the agencies above named as possible causes of the striation, but the matter is for the present lett to those who have studied the phenomena in the field. Four of the specimens described were not much, if in any way, worn by water. They were not, therefore, transported to their position in the midst of clay or sand by running water acting upon them under ordinary conditions. The writer has seen boulders four feet in diameter transported by the rush of water during a cloud-burst in Colorado, and left in the midst of mud and fine sand. If the boulder-bed were formed subaerially, and in a region of severe and sudden storms, the smaller boulders might possibly be accounted for as due to the rush of rapid waters over a soil deposited by rains of ordinary kind. Such a soil if subsequently eroded by the sea or a lake would become stratified and would contain the boulders previously strewn over the region, they being little, if at all, rounded during the erosion of the mud and soil. Still another method can be named for transporting the scratched stones and boulders to their present positions in the midst of clay or sand. A water-logged stratum of clay or shale is more likely to cause a landslip than any other kind of rock. Suppose such a mass of sedimentary clay to have been deposited over crystalline por- phyries previously shattered into boulders of decomposition. If afterwards the region is elevated so as to become part of a mountain range adjacent to the sea or a lake, subaerial erosion would begin to lay bare the underlying rocks, and the waves would form a zone of shingle along the beach. If, subsequently, landslips should occur along the mountain-sides, the clay would carry with it into the sea or lake many of the underlying boulders of decomposition and portions of the beach gravels. Many of the stones might be facetted and striated during the landslip, and we should now find them scattered through the clay or sand involved in the slip. And if this clay or sand were subsequently eroded by the lake or sea-waves, the larger stones would still be left in the midst of the fine material, being but little worn or polished during the process. The hypothesis of the stones and boulders found in the midst of A. Somervail—The Lizard Greenstone. 495 the fine sediments having been dropped by floating-ice also well accounts for the deposition of the boulders without much water-wear. This was the theory suggested by Dr. Blanford many years ago, and on the whole is the most probable of any of the theories suggested. It may be that these boulders were not all transported in the same manner. The clays and sands that were formed off the shore of the sea in Maine during the “Champlain” elevation of the sea are strewn with erratic boulders up to twenty feet in diameter. The clays are fossiliferous and must have been formed in the open sea. The boulders were dropped from floes of shore-ice or small bergs. Every winter the shore-ice becomes attached to boulders, and in the spring these boulders are carried out to sea and along the coast when the ice becomes detached from the shore. This hypothesis therefore _ postulates a process that is known by actual observation to be an efficient one. It is not the writer’s purpose, however, to enter on the general question. The character of the specimens imperatively demands some method of transportation that did not involve much water-wear and permitted the preservation of the scratches on the surface. But the specimens afford little evidence as to the exact manner of their transportation. Cotorapo CoLLeGE, Cotorapo Sprines, U.S.A. X.—On THE GREENSTONE aND AssocraTED Rocks oF THE MANACLE Point, Lizarp. By ALEXANDER SOMERYVAIL. N De La Beche’s Geological Survey Map of Cornwall are three colours representing the associated rocks at, and on each side of the Manacle Point. The Point itself and for a considerable distance south of it is represented as a greenstone. Partially encased in the greenstone and to the south of it is gabbro, which forms the main mass of this rock in the Lizard district. On the north side of the greenstone which forms the extreme south wall of Porthonstock Cove is hornblende-schist, which with some serpentine and other rocks terminates against the killas, or slates near Porthalla. Several observers with seeming good reason have drawn attention to the fact that the greenstone as represented on the map is made to cover much too large an area to the south, and that any one walking from this direction, or the reverse, finds gabbro where the former rock was expected to occur. That this is the case, there is absolutely no doubt, but, De La Beche may have had his own reasons for this, although perhaps not distinctly stated in the text of his accom- panying memoir. Not only does this seeming discrepancy exist with regard to the relative extent of these rocks, but one also soon seems to get involved in another with regard to their relative ages. It has been taken for granted somehow or other that the green- stone is the newer rock, as it seems to cut the gabbro; but at Porthonstock this is entirely reversed, the gabbro in several instances traversing the greenstone. 426 A. Somervail— The Lizard Greenstone. From the commencement of the greenstone on the south side of Porthonstock Cove, as indicated on the map, there is little more than a repetition of alternate greenstone and gabbro for a considerable distance to the south. At first the greenstone is the predominating rock for a short distance, then both almost in equal proportions. The gabbro in its turn, however, soon preponderates, yet still having a number of bands or veins of the greenstone, these becoming fewer — as the central mass of the gabbro is reached. These bands and veins of greenstone differ considerably from each other seemingly in proportion to their width and in their relations from the more central mass of the gabbro. Some of them are like dolerites, others like diorites, and both are frequently porphyritic, and not to be distinguished from similar rocks much further south associated with the granulitic group which cuts the serpentine. These veins, where I first saw them near the southern limit of the greenstone on the map, firmly impressed me with the conviction that they were due to segregation. During a moderate falling rain I was able to examine them to much advantage, the wet on the rock brings out the very decided way in which the veins shaded into the matrix of the gabbro. Repeated examples bore out the same con- clusion, and the broader bands pass in a similar way into the mass of the gabbro, without the slightest sign of intrusion, or of any force having been exerted, or the margins of either having been altered in the very least degree by contact. The example already referred to of the Porthonstock gabbro traversing the greenstone, so apparently contradictory, is also, I believe, due to segregation from the more extensive mass of the greenstone occurring at this point; so that on the ground of segre- gation, anomalies and difficulties at once disappear. I have no doubt that it was from the successive bands of both rocks at Por- thonstock Point, that De La Beche was induced to colour so much of this area as greenstone, if not from the very reason just given. There can be no doubt but that the greenstone and gabbro are por- tions of one and the same magma, the gabbro on its northern margin passing into the former, and as we shall presently see, the horn- blende schists immediately north of the greenstone are formed out of this latter rock,’ so that all three—gabbro, greenstone, and horn- blende-schist—are but the modifications chemically and mechanically of one mass, although represented by the three colours alluded to. From south to north, as already stated, there is a gradually growing disposition on the part of the gabbro to become more split up by the segregated greenstone veins and bands, until these become the dominant rock at and north of Porthonstock, resulting in what is now represented by the hornblende-schists north of that locality. The greenstone of Porthonstock is not by any means a rock that has undergone any very great amount of secondary alteration. Immediately north of it, however, there is evidence of a plane of great disturbance which has much more completely altered its original constituents, especially its augite into hornblende, and pro- ' This opinion is expressed in Prof. Sedgwick’s paper, Trans. Cambridge Phil. Soc. vol. i. p. 18. } Notices of Memoirs—A Head of Hybodus. — 427 duced a highly schistose structure. Its various mineral constituents are much crushed, flattened and broken up into fine fragments, the long axes of which conform more or less to the planes of cleavage produced by the great mechanical pressure the rock has here undergone. The original porphyritic structure, though much crushed, is “yet distinctly traceable, and further north, where the rock is less cleaved or schistose, as towards Porthkerris Cove, and Point, the porphyritic structure much abounds. There is another point with regard to the Porthonstock greenstone which must not be overlooked, that is, the tendency of the rock in parts to assume the granulitic structure, which, although on a small scale here, is yet the same type of rock as met’ with in the southern -areas. This also is, I contend, but a portion separated from the greenstone by segregation, so that from the parent mass of the gabbro has been evolved the. granulitic and the greenstone, which latter by subsequent dynamical movements has “been converted into horn- blende-schist. This explanation I am inclined to regard as no mere speculation, but as a fair and just inference based on what we can observe in many localities at the Lizard. In some of these localities all three rocks, gabbro, granulitic, and hornblende, are more or less inter- changeable, and a distinct passage can be traced between them all. In certain areas large tracts of the latter rock, which seems to have formed the upper or outer margin of the gabbro, have been cleaved into what now form the schists, while the more granulitic portions, although closely adjoining, have from their coarse and granular nature been much less affected. It will, I think, be ultimately found that segregation has played a most important part among all the rocks of the Lizard district. The bands of hornblende so frequently occurring in the serpentine in various localities are due, J think, to this cause. The dykes in the outer rocks off the Lizard Mende mapped with such care, and not without danger, by Mr. Howard Fox, F.G.S.,’ are, I believe, true segregation dykes. The banded structure in the hornblende- schists and associated gneissic rocks is also in my opinion due to this same cause, a subject I hope to deal with very shortly. If the present suggestion is correct, in reducing the triple division of the rocks at the Manacle Point to mere varieties of one original magma, it seems to go a long way towards simplifying the seology of the rest of this most interesting district. iO ae bC i S51 Oi Iver VE} ees 1. “On a Heap or Arzopus DrtaBecHrI, ASSOCIATED WITH DorsaL HIN-SPINES, FROM THE Lower Lias or Lyme Recis, Dorser- suire.” By A. Smrra Woopwarp. Ann. Report Yorksh. — Soc. 1888, pp. 58-61, pl. i. HROUGH the generosity of Mr. William Reed, F.G.S., the Mode shire Philosophical Society is enabled to publish, in its recently- issued Report for 1888, a fine quarto plate (drawn by Miss G. M. 1 On the Gneissic Rocks off the Lizard, Q.J.G.S. May, 1888, p. 309. 428 Reviews—Beeby Thompson's M. Lias, Northampton. Woodward) of the most perfectly preserved head of the Liassic Shark, Hybodus Delabechei, hitherto discovered. The specimen is contained in the Reed Collection of the York Museum and exhibits, for the first time, the precise arrangement and relative proportions of the teeth, in addition to some of the characters of the cranial cartilage. The mandibular teeth are disposed upon each ramus of the jaw in ten or eleven transverse series, being thus more numerous than in Acrodus; and there is no azygous series of symphysial teeth. The dorsal covering of shagreen is sparse, and the absence of barbed, lateral head-spines is somewhat remarkable. 2. Fis Remains From THE Lower Coat Mrastres or LANCASHIRE. By Herzsert Botron. Trans. Manchester Geol. Soc. vol. xx. pt. viii. 1889. HE author records the occurrence of fossil fish remains in shale overlying the Upper Foot, or Bullion Mine Coal, in Rossendale, and publishes brief notes upon the specimens. A large Hlonichthys appears to be referable to Z#. semistriatus, Traq.; a head of Celacan- thus is shown to differ in some respects from that of the common C. lepturus ; and other less satisfactory fragments do not permit of any tolerably precise determination. 3. “ UEBER ZWEI Fiscoe aus DEN ANGULATUSKALKEN DES UNTER- Eusass.” By W. Descxe. Mittheil. Commission geol. Landes- Untersuch. Elsass-Lothringen, vol. i. 1888. 11 pp. 1 pl. i eo author describes a new species of Heterolepidotus and another of Dapedius from the Angulatus-beds of Alsace, and claims these to be the oldest Liassic fish-remains hitherto discovered. Heterolepidotus angulati is founded upon the well-preserved trunk of a typical member of the genus, closely related to 7. serrulatus, but differing in the smoothness of the scales. Of Dapedius cycloides, a complete fish forms the type-specimen, and this seems to differ from the well-known D. orbis of Barrow-on-Soar, merely in the prominent sculpturing of the scales upon the foremost half of the trunk. Of the Heterolepidotus a description alone is given ; but of the Dapedius there is a good photograph, with explanatory lettering upon a traced outline of the fossil. SEC Es OV) EES VE SS J.—Tse Mippir Lis or NortHampronsHire. By Beesy Tuomeson, F.G.S., F.C.S. (London, Simpkin, Marshall, & Co.) 8vo. pp. 150. Price 3s. 6d. INCE the days when Samuel Sharp laboured so successfully among the Oolites of Northamptonshire, no one has studied more assiduously the county geology than the author of the present work. Confining his attention mainly to the country accessible from the town of Northampton, he has added largely to our knowledge of the Upper Lias, in papers published in the Journal of the North- amptonshire Natural History Society; and he now gives us the ” ‘ B L- Reviews—Beeby Thompson’s M. Lias, Northampton. 429 results of his observations on the Middle Lias. The work itself has appeared in serial form in the ‘‘ Midland Naturalist,” but the author has done well to reprint his papers in a neat and handy volume, and so save them from the oblivion which too often befalls many ex- cellent articles. Two main subjects are treated of and discussed: 1, the Middle Lias, stratigraphically and paleontologically ; and 2, the Strata in their connection with Water-supply, etc. In the first portion we are given detailed notes of many sections, and, what is of most importance, records of fossils obtained from each minor division of the strata. When we learn that these divisions amount to thirteen in all, we may confidently assert that the position of each assemblage of fossils in the Middle Lias has been worked out much -more minutely than in any other area in this country. In saying so much, we do not attach undue importance to these minor or perhaps local divisions ; but inasmuch as the author founds his work on the stratigraphical sequence of the beds, his facts and conclusions will be of great value to other workers, who are endeavouring to trace out the biological history of the species. Some forms are for the first time recorded from the strata in this country ; while others altogether new, obtained by the author, and by another zealous worker, Mr. W. D. Crick, have been recently described by Mr. EH. Wilson in the pages of this Macazinu. The so-called “'Transition-bed” between the Middle and Upper Lias, a bed previously discovered and worked out on the borders of Oxfordshire and Northamptonshire by Mr. T. Beesley and Mr. E. A. Walford, is described as fully as possible. Stratigraphically it is a very insignificant bed, but a few inches in thickness, so that whether it be regarded as Middle or Upper Lias is a question in no ways calculated to disturb the mind of the geological surveyor. It has yielded a fauna of upwards of 90 species—about three-fourths of which belong to the Middle Lias and one-fourth to the Upper Lias. The Ammonites are essentially Upper Lias types, and these include the characteristic Ammonites acutus. The Gasteropods are of Middle Lias character and suggest that the bed is approximately ‘on the same horizon as the ‘Pleurotomaria-bed’ (of Mr. E. ©. H. Day) on the Dorsetshire coast. Mr. Thompson includes in his Middle Lias only the zones of Ammonites spinatus and A. margaritatus; thus putting the beds with A. capricornus, A. Henleyi, etc., in the Lower Lias—a grouping adopted by the Geological Survey. All the evidence, however, goes to show that the larger as well as the smaller divisions are intimately linked, and the Upper Lias beds in Northamptonshire appear in places to be closely connected with the Northampton Sands, as pointed out elsewhere by the author. Passing on to the second portion of this work, we find a notice of the Economic products, and then a general account of the Springs in the Gravels and Oolites. The latter portion of this subject is but introductory to a special account of the water-bearing beds of the Middle Lias. 430 Reviews—Beeby Thompson’s M. Lias, Northampton. Owing to the increased amount of water needed for the town of Northampton, and partly owing to improved systems of agricultural drainage, the water derived from the deep wells in the Middle Lias was found to be insufficient, Still deeper wells were made in the hopes of reaching water- -bearing: Triassic rocks; but these were failures. Mr. Thompson has for some years past advocated that a system of dumb-wells be constructed—about 100 feet in depth on the average. “These dumb-wells would all be situated in the valleys, and would generally require to be cut through a little alluvium and river gravel, and through the Upper and Middle Lias. The wells might be lined with brick, and then filled up with coarse gravel, broken brick, or any good porous material to within 36 ft. or 40 ft. of the top, the material to get finer towards the top, in imitation of the filter beds of the London water companies. The depth of 38 ft. to 40 ft. not filled with gravel is given to enable the water running in from the river gravel, as well as that from the surface, where such water is desirable, to have a good fall, whereby it may be effectually aerated before entering the chief filter bed.” The author would take advantage of the river gravel as a primary reservoir and filter-bed, whence the water would be conveyed into the Marlstone. He mentions that at the present time water obtained from the river gravel is clear, and free from suspended impurities, and would still be so if his plan were adopted, so that, in his opinion, there would be little or no silting up of the dumb-wells. Additional supplies of water might also be obtained from the river by means of pipes when the water was sufficiently high for it to be well spared, and this would tend to prevent the injuries that arise to the banks from overflowing. The author, therefore, contends that his scheme, of which he gives full details, would improve a large district now injured by floods; it would furnish an abundant water supply in a natural reservoir (the Middle Lias); and the water would be very pure, because it would be filtered before entering the well, and filtered again in the well before entering the most effectual filter the Marlstone itself, while it would be well aerated by its fall. Various objections have been raised against this scheme, and these are fully discussed by Mr. Thompson. Perhaps the most serious objection is that a scheme of this nature has not been tried before in this country, and that it must necessarily be an experiment. Such an objection might have been urged against some of our deep borings! Another question is whether the water would go away through the dumb-wells. Water obtained from old wells was of an artesian nature rising formerly at one place 90 feet above the water- bearing rock. This, however, was before the water-level had been reduced by the large supplies procured, and so long as large supplies are pumped up, there would be no danger of overflow from the dumb-wells. The dip of the beds is considered too slight to offer any obstacles to the scheme. The Upper Lias is 170 to 190 feet thick, and the author calculates that there could be a head of water of 110 feet at Northampton, before the dumb-wells would cease to act or occasion loss. Reviews—Dr. C. F. Major’s Fossils of Samos. 431 The scheme, however, was not adopted by the Town Council of Northampton—as it was considered too theoretical by the “practical” men; moreover it was deemed necessary to procure a supply without loss of time, and an artificial reservoir to hold 400 millions of gallons of water has been constructed near Ravensthorpe. Mr. Thompson claims that his plan, if successful, would have saved the town at least £75,000; hence it seems a pity that it was not given a trial by the construction of one or more experimental dumb-wells, for we feel confident that the plan could not have been proposed under geological conditions more likely to prove favourable to its success. _ Those occupied in the subject of water-supply will, however, find in this carefully-prepared work much matter of interest and instruction; and the author need not feel that his labour has been unproductive of good, even if he has not been considered as a “ prophet” in his own country. Il.—Dr. C. ForsyrH-Masor’s Pat#ontoLtoGicaAL D1IscovERIEsS IN THE IsLE OF SAMOS. A Sur un Gisement p’Ossements Fosstnes pans L’[tm pr Samos, CONTEMPORAINS DE LAGE DE Pixermi. Par M. Foxrsyra Magor. Comptes Rendus, vol. evii. pp. 1178-1181 (1888). HIS paper contains a preliminary notice of a collection of Vertebrate remains of Lower Pliocene age obtained by the author during the year 1887 in the island of Samos in the Turkish Archipelago. Among these are a large number of forms specifically identical with the mammals from the equivalent deposits of Pikermi in Attica, Baltavar in Hungary, and Maragha in Persia; but there are also some new types, which are of interest either from a distribu- tional or a purely zoological point of view. Among these new forms is a species of Ant-bear (Orycteropus), which is the only representative of that genus yet known beyond the Ethiopian region. A large Pangolin, which is estimated to have been nearly three times the size of the West African Manis gigantea, is made the type of the new genus Palgomanis; and is of interest as showing how the African Pangolins may have been connected. with those of India. Perhaps the most striking new type is a large ruminant referred by the author to the Giraffide, and stated to connect Helladotherium and the Giraffe with some of the aberrant Antelopes of Pikermi. Finally a large Ostrich is especially noteworthy from a distributional point of view, since we now have remains of this genus from Samos, the Thracian Chersonese, and Northern India. R. 1: Notr.—We learn that Dr. H. Woodward has just returned (20 August) from Florence, having secured Dr. C. Forsyth-Major’s valuable collection from Samos for the British Museum (Natural History), Cromwell Road, to which it will doubtless prove a most important addition. 432 Miscellaneous—H. P. Woodward. MIiSCHUiLANHOVUsS. Coat anD Trin Discoveries IN WESTERN AUSTRALIA. Mr. Harry P. Woopwarp, F.G.S8., Government Geologist for Western Australia, sends some interesting particulars of both coal and tin discoveries in that colony. He writes :— ‘‘ From Vasse I made for the Lower Blackwood River Bridge, over the foot of the Darling Range, and so on to the Donelly River. On the south coast, where a small stream flows out, called the Fly Brook, coal has been found of a very good quality, but there is no port nearer than Albany or Vasse, and this latter is not a good one. There seems to be a line of coal-bearing country between the coast- range, which runs north and south from Cape Leeuwin to Cape Naturalist, and the main highlands, the southern continuation of the Darling Range, covered with sand and swamps at the surface, but under these I believe we shall find Coal-measures which may in fact extend west beneath Perth to the Irwin River, but this can only be tested by deep-borings. “There was nothing to be seen of the coal or rocks, as they are boring with a ‘jumping-drill,’ which reduces everything to mud, but there is one 5ft. seam and several smaller, averaging 17ft. of coal in 200 feet of rock. ‘There are two or three outcrops in the bed of the Creek of a much weathered but good coal, some of which is highly bituminous. From Bridgetown I went to Albany, and thence east 200 miles to the Phillips River, and saw the Fitzgerald Coal- field. This is only brown-coal or lignite of no value, but there is some good-looking gold-bearing country near it.” 'l'in-onE.—In reference to the Tin-discoveries Mr. H. P. Woodward writes :— “From Bunbury I went towards the Upper Blackwood, to a place called Bridge-town, where tin has been met with : little work has been done yet, but, as far as 1 am able to judge, it seems to indicate the biggest thing of the kind that has ever been found. One shaft 18ft. deep will ‘ wash’ all the way down at about four or five lbs. to the pan, and they have not got to the bottom of it yet. The richest works in other Colonies are rarely more than two or three feet deep. Tin has been found at the surface, in the sand, over an area of about 100 square miles; but no sinking, except the one shaft, has yet been made; and as the surface is covered, either with sand or clay-iron- stone, the formation cannot be seen at all. The late Mr. Hdward T. Hardman, F.G.S., suggested that tin would be found here. The shaft shows a few inches of soil or alluvium with gravel containing tin, where it was first found, resting on hard masses of clayey ferruginous sandstone, about one foot thick, then coarse quartz-grit with stream-tin and tourmalines and a few ‘colours’ of gold. 17ft. not gone through yet, as there was too much water: about % in weight being tin-ore.” Errarum.—In the first part of Messrs. Wilson and Crick’s paper on the ‘‘ Lias Marlstone of Tilton,” in the July Number, pp. 296-305, Hast Norton was by mistake stated to be in the county of Rutland instead of Leicester. a | Geol Mag 1889. = oh al nian TTS MaAGNetic Cu oF JAPAN, eee RVES. aes ae Geol Mag 1889. | (= See | | a ee — ct i TECTONIC MAP| or JAPAN, ae be KNQTTS MAGneTic Curves. = = ae | | / > ~~ HORIZONTAL | ° | val || a 3 4 Yah La i af ft Gane (351) ta\> (Menian Fisbu INTERRUPTED, -~ | net Af eo | | Tl ine SAE 177 By Se HORIZONTAL cS \INTENSITY 2 | hah \ | el / | 56 = Te i i oD > | Li, Ee | 1 lh | -7 | - alles esl Hird -_ | a Vzaka \ 4 | ae | | ce RAL $ | a | aii | | | | aS | %, | bs | | | | { a} | | _—— 1 | | a i I ! 1 } il 4] ! i ee eg | = i) 136 [ti LESS) ae ERE It) Woat, Newman lith. lanns Memoir. Geol.Mag 1889. ee D i MP SEKINOS ano D* K + | | = OG NOTTS JAPAN. - Saas fo) MAGNE } 7 +. i Mr. Sekinos awl Dr. Knotes shown this = wove = ee _ Decade II!.Vol VIP) XVIII To illustr BIE D? Naumann’s Memoir. ‘ = Geol. Mag.1889. Decade Ill Vol.VI.PLXIX. A = NX co = -- > Decade IIVeL V1 PL XV. . Geol. Mag MSS). LOCKE'S MAGNETIC SECTIONS. § > = S PATTERSON.N.d. 8 = : a) PALISADES OF THE HUDSON. 8 iS AS 75° 106 4 | iS Bleep aici | ile 1,30 40 1Q5¢ vs ~ 20 | IQ 74° Sa 20 0 73° ioc Pee Of } | e z ori ty) eG g COLTS GAR To iHustrate D? Naumann’'s Memoir on Terrestrial Magnetism. | West, Newman) ith. co LCST O24 ee KUNE NIL yy A ii 5S TH os MN Ni “aren: er ”y 425" 2a EZ . AN Mey | = oat i UL < 4 ain ay, 2! Nye, é TNE ANN ANT, “hy ir. i HSA ewer nyn AOL Ap zs UE : He Hi iW Cin RING Hie 7 TNA ee To illastrate D" Naumann's Memoir on Terrestrial Magnetism. THE ; GEOLOGICAL MAGAZINE. NEW SERIES. DECADE III. VOL. VI. No. X.—OCTOBER, 1889. Oi Gam ASE,) ANE eG aaa. ——_—___ T.—On tur RELATIONS BETWEEN THE GENERA Syrive@ozires, Hinde, AND Rorvert4, Epwarps anp HaimE, AND ON THE GENUS Cati4pord, SCHLUTER. By H. Atteyne Nicuotson, M.D., D.Sc., F.G.S., Regius Professor of Natural History in the University of Aberdeen. N a recent publication (‘ Anthozoen des rheinischen Mittel-devon,” 1889) Professor Schliiter has put forward the conclusion that the genus Syringolites, Hinde, is identical with the much older genus Roemeria, Edwards & Haime, the former name thus becoming a mere synonym. From this conclusion I feel obliged to dissent, and I propose to show in the following brief communication that Roemeria and Syringolites are distinguished by important morphological characters, and that the latter is fully entitled to generic rank. The genus Syringolites was founded by Dr. Hinde (Gzon. Mac. Dee. II. Vol. VI. p. 244, 1879) for the reception of a beautiful and interesting coral from the Niagara Limestone of Canada, to which the name of S. Huronensis was given by its describer. The same species has subsequently been recognized as occurring in the Wenlock Limestone of Gotland. The corallum in S. Huronensis (Fig. 1) is composite and has the form of a flattened expansion, furnished with a basal epitheca, and closely similar in general aspect to specimens of the massive forms of Favosites, such as Ff’. Gothlandica. The corallites resemble those of Favosites proper in being prismatic, Fic. 1.—a, A fragment of a colony of Syringolites Huronensis, Hinde, of the natural size; B, A single calice of the same, enlarged eight times, showing the central tube, and radiating lines of septal tubercles; c, Part of a corallite of the same, split open, and enlarged six times, showing the composition of the central tube out of invaginated tabule; p, Part of a corallite of the same, viewed from the exterior and enlarged six times, showing the mural pores. Niagara Limestone, Manitoulin Island, Ontario. DECADE III.—VOL. VI.—NO. X. 28 434 Prof. H. A. Nicholson—On Syringolites, Roemeria, etc. thin-walled, closely contiguous, and furnished with one or more rows of small mural pores on each prismatic face. The corallites are intersected by numerous annular tabule, which are invaginated centrally so as to give rise to a median cylindrical tube, which occupies the centre of each visceral chamber, and is furnished with imperforate walls. The upper surfaces of the tabule show well- marked septal ridges (primarily twelve in number), which are covered with minute tubercles or spines, two to four rows of such tubercles apparently corresponding with a single septal fold. Increase of the corallum takes place by intercalicinal gemmation. The essential characters of Syringolites Huronensis, as above briefly described, are that the prismatic corallites are thin-walled, and are furnished with numerous regularly-distributed mural pores, while the septal system is fairly represented by radiating tuberculated ridges, which are primarily twelve in number in each corallite. The only corals which have been recognized as belonging to the genus Roemeria, H. & H., are the R. (Calamopora) infundibulifera of Goldfuss, and the R. minor of Schltiter, both of which occur in the Middle Devonian of Germany. I have had the opportunity of examining the original specimens of the former of these, which are preserved in the University Museum in Bonn; but, so far as ] am aware, no complete microscopic examination of these has ever been carried out. There is, however, no doubt that R. minor, Schliiter, is congeneric with RB. infundibulifera, Goldf., and through the kindness of Professor Schliiter, I have been enabled to make a thorough microscopic investigation of the former, which I shall therefore take as the type of the genus Roemeria. The corallum in Roemeria minor forms small flattened expansions, composed of erect, polygonal, and contiguous corallites. Thin sections, both transverse and longitudinal (Figs. 2 and 38), show that the corallites are bounded by a thin and well-developed primor- dial wall, which is enormously thickened by a dense deposit of secondary sclerenchyma (‘stereoplasma”), the visceral chamber being thus greatly constricted. The visceral chamber of the corallites, thus restricted, is traversed by a succession of infundi- buliform tabulae, which are invaginated one into another, but can hardly be said to give rise to a definite median tube. The septa are practically undeveloped, though one may occasionally observe blunt vertical ridges, which are possibly of a septal nature. The mural pores are of very large size, and comparatively few in number, and are quite irregular in their distribution; while owing to the enor- mous thickening of the walls of the corallites, they present them- selves as elongated canals joining the visceral chambers of contiguous tubes. Increase of the corallum takes place by means of intermural gemmation. From the above short description of the structure of Roemeria minor, as illustrated by the accompanying figures of thin transverse and vertical sections, it will be obvious that Syringolites, Hinde, differs in characters of fundamental importance from Roemeria, H. & H. This will be sufficiently evident from the following summary : Prof. H. A. Nicholson—On Syringolites, Roemeria, etc. 435 (1) The corallites in Roemeria are enormously thickened by a secondary deposit of stereoplasma; whereas those of Syringolites are thin-walled, and resemble those of Favosites proper. (2) The mural pores of Roemeria are of large size, are few in number, and are irregularly distributed; whereas those of Syringo- lites resemble the pores of Favosites proper in being of small size, numerous, and regularly distributed. Fic. 2.—Transverse section of Roemeria minor, Schliiter, from the Middle Devonian rocks of Dahlem, in the Eifel, enlarged about six times. p. Mural pore. Fic. 3.—Vertical section of Roemeria minor, Schliiter, from the same locality, similarly enlarged. pp. Mural pores. \ (3) The septal system in Roemeria is rudimentary or absent ; whereas in Syringolites each corallite is provided with well developed septal ridges, the number of these structures in each tube appearing 436 Prof. H. A. Nicholson—On Syringolites, Roemeria, ete. to be primarily twelve, as is the case in Heliolites, Halysites, Syringopora, ete. Upon the whole, therefore, it cannot be doubted that Syringolites, Hinde, is generically distinct from Roemeria, EH. & H.; and it is not even clear that the two are very nearly related. If the septal system of Roemeria had been developed, the genus might be regarded as occupying to Syringolites a position analogous to that held by Pachypora with regard to Favosites proper; and, possibly, this view may be found ultimately to express the real relationships ‘of the two. Both genera afford transitional links between the Fuvositide and the Syringoporide; but their precise relationships must in the meanwhile remain more or less a matter of conjecture. Genus Caxiapora, Schliiter. The genus Caliapora has been proposed by Professor Schliiter for the reception of the well-known Alveolites Battersbyi, E. & H., from the Devonian rocks of Britain and Germany. I have long been of opinion that the peculiarities of A. Battersbyi are such that it is worthy of separation from Alveolites proper, as a distinct genus or Fic. 4.—A. Tranverse section of Caliapora Battersbyi, E. & H., sp. enlarged seven times. B. Vertical section of the same. From the Middle Devonian of Dartington, South Devon. i subgenus; and J am therefore able to cordially concur in the course which Professor Schliter has taken. At the same time I interpret the structure of A. Battersbyi in a somewhat different manner, and I consider that the familiar Alveolites Labechei of the Wenlock Limestone must find a place along with A. Batiersbyi. I cannot, therefore, accept Professor Schltiter’s: definition of Caliapora as altogether sufficient; and I shall endeavour here to indicate what, in my opinion, are the essential characters of the genus. In both C. Battersbyi and C. Labechei the corallum has all the general characters of that of Alveolites generally, and there is there- fore no external feature which distinguishes the genus Caliapora. In C. Battersbyi, as pointed out by Schliiter, the corallites are sub- polygonal and irregular in shape (Fig. 4); but this character is Prof. H. A. Nicholson—On Syringolites, Roemeria, etc. 437 not a vital one, since in C. Labechet the tubes have commonly the compressed form and alternating arrangement which is characteristic of the typical forms of Alveolites. Again, little importance can be attached to the mode of distribution of the mural pores, since in C. Labechei these structures seem to be confined to the short ends of the compressed corallites, whereas in C. Battersbyi they are asserted by Schliiter to occur indifferently- on all the faces of the corallites. Of still less importance is the supposed absence of tabule, since this rests upon a misconception. Not only are tabule largely present in C. Labechei, but, in all the specimens of C. Battersbyi which I have examined, I have found these structures to be fairly well developed, though they are often comparatively few in number (Fig. 4,8). Some of the tabula of C. Battersbyt have the ordinary form of complete transverse plates; but this species is furnished in addition with numerous imperfect, cup-like tabulee, which project but a short way into the visceral chamber of the corallites, and which have been compared by Professor Schliiter with swallows’-nests attached to the wall of a house. In C. Labechei all the tabula seem to be complete, and there are none of the peculiar incomplete or squamous tabulee which occur in C. Battersbyi. Fic. 5.—A. Transverse section of Caliapora Labechei, K. & H., sp. enlarged six times. B. Vertical section of the same, similarly enlarged. From the Wenlock Limestone of Much Wenlock. The most characteristic feature of the genus Caliapora, as com- pared with Alveolites, is to be found in the fact that the corallites are provided with numerous strong ascending tooth-like processes, which must be regarded as of the nature of septa (Figs. 4 and 5). The existence of these strong tooth-like spines in Caliapora Bat- tersbyi is recognized by Schliiter, but they are regarded as being due to the intersection of the cup-like squamous tabulz above spoken of. In this view of their nature I am unable to agree, and I regard them as structures having an independent existence. This is clearly the case in C. Labechei (Fig. 5), where their septal nature is quite in- disputable. If this view be correct, then the essential feature which distinguishes Caliapora from Alwveolites is the possession by thie former of strong tooth-like septal spines, which are developed in 438 Prof. E. D. Cope—On the Proboscidea. a cycle within each corallite in C. Labechei, but are fewer in number in C. Battersbyi. Finally, it may be pointed out that in typical examples of C. Bat- tersbyi there appears to be the peculiar feature that the walls of certain of the corallites seem to be specially thickened, thus giving rise to strong vertical spines, which constitute a conspicuous feature in vertical sections. J have had no opportunity of observing the termination of these spine-like thickenings on the surface, and I am not clear as to their real nature. IJ.—Pror. E. D. Corn, on THE PROBOSCIDEA. (PLATE XIII.) HE following account of the Proboscidea, by Prof. H. D. Cope, appeared in a recent number of the “American Naturalist,”* and is so interesting, that we venture to give the more important part in full, and some few of the illustrations.—Hpir. Grou. Mac. “The Proboscidea are Ungulata, in which the second row of carpal bones has not moved inwards, so as to alternate with the first, and in which the second row of tarsal bones alternates with the first by the navicular extending over part of the proximal face of the cuboid. The teeth are modifications of the quadri-tubercular type, and canines are absent. To these general characters are added numerous subordinate peculiarities in the known genera and species, which make them among the most remarkable of living beings. These peculiarities are the result of a long period of development. It is one of the most curious facts of paleontology that the order does not make its appearance until the middle of the Miocene system, and the greater number of forms do not appear until the upper Miocene. That it existed earlier cannot be doubted, and that it originated from some Hocene Condylarthran is evident ; but the intermediate forms are entirely lost to us as yet; and the phylogeny of the order is absolutely unknown. This is the more extraordinary, since the earliest known genus (Dinotherium) embraces only species of colossal size, and its immediate ancestors could not have been insignificant. We may regard Phenacodus as the first form we know of earlier than Dinotherium, but what a hiatus is expressed in this statement. It is to be anticipated that the gap will be filled by discoveries in Asia, or the Southern Hemisphere. South America may be probably excluded from this prospect, since the extensive researches made there by Burmeister, Ameghino, and Moreno, have not resulted in the discovery of any Proboscidea earlier than the Pliocene. Asiatic investigations have revealed nothing, as the proper formations have not been found, and the same is true of Africa. So we shall have to wait until the paleontology of the present home of the order is exposed to view, before we shall know of the steps which lead from Phenacodus to these mighty monarchs of the animal kingdom. The absence of primitive Proboscidea from North and South America and Europe, impels us to believe that the representatives of the order known to us from those regions are the descendants of immigrants from Asia and Africa. 1 No, 268, April 1889, pp. 191-211, pl. ix.-xvi. and nine woodcuts. Prof, E. D. Cope—On the Proboscidea. 439 - But two families of Proboscidea are known. ‘They are defined as follows : Adult dentition embracing premolars and molars; no superior Incisors—Dinotheriida. Adult dentition embracing one or two true molars only ; superior incisors—LHlephantida. The family of the Dinotheriide embraces one genus and four species, though a fifth species, D. sindiense, Lyd., from India, may belong, according to Lydekker, to another genus. The Dinotherium indicum, Falc., is known from a few teeth, which exceed in size those of the other species. The D. giganteum, Kaup, is found in several Fig. 1.—Dinotherium gigantewm, Kaup, from the Middle Miocene of Samaran (Gers), France. (After Gaudry.) ‘The left upper cheek-dentition ({ nat. size). a@ 1, 2, 3, true molars, p. 8, 4, premolars. Miocene deposits of HKurope. It was one of the largest of Mammalia, its femur exceeding in dimensions that of any other land mammal. The inferior incisors were robust, and cylindric in form. With the symphysis of the lower jaw they are decurved so as to form a most effective instrument for the tearing up of trees by the roots, or the pulling down of their branches. ‘The temporal fossa is lateral, and the top of the head flat. The premaxillary region, though toothless, is prominent, and the nasal bones do not project. There is supposed to have been a short trunk. The skull measures three feet eight inches in length. Two smaller species are known, the D. bavaricum, from European, and D. pentapotamia, from Indian, Miocene beds. In Dinotherium all the molars and premolars have two transverse crests, excepting the first (posterior) premolar, and its deciduous predecessor, which have three cross-crests. The genera of the Hlephantide are the following : I, Inferior incisors and premolars present. Superior incisors with enamel band— Tetrabelodon, Cope. II. Premolars, but normally no inferior incisors ; intermediate molars isomerous ; superior incisors with enamel-band — Dibelodon, Cope. Intermediate molars isomerous ; superior incisors without enamel band—Mas- todon, Cuv. Intermediate molars heteromerous; superior incisors without enamel band— Emmenodon, Cope.} III. No premolars, nor inferior incisors. Intermediate molars heteromerous. Superior incisors without enamel band— Hlephas, Linn. 1 Gen. noy. type, Hlephas Cliftii, Fale. & Cautl. (Mastodon elephantoides, Clift). 440 Prof. E. D. Cope—On the Proboscidea. The characters assigned to the above genera are sufficient to separate them, but they have not come into general use for two reasons. One is the difficulty of verifying some of them, especially the presence of premolars, owing to the difficulty of obtaining specimens of young individuals. The other is the indisposition of naturalists to abandon the system of Falconer. As is well known, this able paleeontologist distinguished the genera by the number and depth of the transverse crests of the molar teeth, and the extent to which their interspaces are filled with cementum. This arrangement is insufficient, since it neglects the equally important characters above mentioned ; and as observed by Lydekker? it fails to furnish clear definitions. He remarks, under the head of the genus Elephas :— “There is no character by which the present genus can be dis- tinguished from Mastodon; and the division can be therefore only regarded as a matter of convenience.” The characters presented in the above table are on the other hand very distinctive, and can be applied in all cases where we have the necessary information. This has not yet been obtained as regards all the species, and I have placed some of them in their respective genera provisionally. Such species are marked with an 7, when the condition of the incisors is unknown and with a p, when the same is true of the premolars. The species of the family described thus far are as follows: ?— Mastodon (Tetrabelodon) brevidens,® Cope, sp. nov.. N. America, i.p. vs . turicensis, Schinz. Kurope. +3 rp angustidens, Cuy. , Kurope. Ae Dein - paleindicus, Lyd. India. Ap a A proevus, Cope, N. America. 6 a productus, Cope. N. America, ? Mexico. ie is . euhypodon, Cope. N. America, p. or A pandionis, Falc. Cautl. . India. is re pentelict, Gaudry.* Europe, p. Ge a3 campester, Cope. N. America, p. an a longirostris, Kaup. Europe. HS P serridens, Cope. Texas, ? Mexico, ? Florida,® z.p. Fe (Dibelodon) shepardi, Leidy. California, Mexico, p. “p A cordillerarum,® Desm. S. America. an Mt tropicus, Cope. S. America and Mexico, p. “) humboldti, Cuv. S. America. Mastodon americanus, Cuv.’’ N. America. ii borsoni, Hays. Europe, p. ye faleonert, Lydd. India, p. + mirificus, Leidy. N. America, zp. a sivalensis,® Cautley. India, p. 1 Catalogue of Fossil Mammalia in the Brit. Mus., pt. iv. p. 72. * In compiling this list I have been greatly aided by the Memoirs of Lydekker in the “ Paleontologia Indica ’’ and the Catalogue of the British Museum. 3 M. proevus, Cope, 1884, not 18738. 4 According to Lydekker no premolars have been seen in this species. > M? floridanus, Leidy. 6 M. andiwm, Cuv. According to the recent researches of Burmeister, this species does not possess mandibular tusks (Sitzungsb. Kén. Preuss. Akad. Wiss., Berlin, 1888, p. 717). Hence the specimen from Mexico with such tusks, reported by Falconer, must be assigned elsewhere, 7 This species is said by Lydekker not to possess premolars. Leidy, Report U.S. Geol. Surv. Terrs. Pl., figures a tooth as a premolar, and similar specimens are not uncommon, ® According to Lydekker, premolars have not been observed. DECADE III. Vou. VI. Pu. XIII. GEoL. Mac. 1889. Forms oF ProposcipEan Mo.nars. To illustrate Professor E. D. Cope’s paper on the Proboscidea. Prof. E. D. Cope—On the Proboscidea. 44] Mastodon arvernensis, C. & J. Europe. ? pumjabiensis, Lyd. India, p. ne latidens, Clift, India. Emmenodon elephantoides,! Clift= Elephas, Cuiftii. India to Japan. (Zi.) os planifrons, Fale. & Cautl. India. ; Elephas bombifrons, Fale. & Cautl. India, ? China. ganesa, Fale. & Cautl. India. é insignis, Fale. & Cautl. India to Japan. _[N. Africa. meridionalis, Nesti. Middle and South Europe, and hysudricus, Fale. & Cautl. India. antiquus, Fale. Europe. ? W. Africa. mnaidriensis, Leith-Adams. ‘Malta. melitensis, Fale. Malta. namadicus, Fale. & Cautl. India to Japan. primigenius columbi, Fale. N.W. America and Mexico. primigenius, Blum. Northern Hemisphere. americanus, De Kay. N.E. America. 99 a9 99 %” 99 Fic. 2.—Wastodon longirostris, Kaup, Upper Miocene, Eppelsheim, Hessen- Darmstadt. (After Gaudry) the left milk-molars (nat. size). To these we must add the two existing species Hlephas africanus and H. indicus. Several species are not sufficiently known for refer- ence to their proper genus. Such are Mastodon perimensis, Falc., Cautl., India; M. atticus, Wagn., 8. Europe; M. serridens, Cope, Texas; M. cautleyi, Lyd., India; and M. obscurus, Leidy, N. America. In these the characters of both the incisor and the pre- molar teeth are unknown. In some of the species referred above to Mastodon, mandibular tusks are present in the young, and occasion- | ally one is retained to maturity, as sometimes seen in M. Americanus. But such individuals are exceptional among their species. In some other species, while the males possess them, they are wanting in the females. The specific character is in this case derived from the male. The molar dentition in this family possesses a number of pecu- | liarities which have been worked out mainly by Falconer, Owen, and Lydekker. There are probably deciduous molars in all the species, and they are generally three in number; the posterior of these has the same number of cross-crests as the posterior premolar, which immediately succeeds it. The number of crests diminishes to the first of the series. There are two or three premolars in most 1 Mastodon, Clift.; Stegodon, Fale.; Elephas, Lyd. 449 Prof. LE. D. Cope—On the Proboscidea. forms of the family, but in the genus Hlephas they have disappeared. In all the species they are shed early in life in order to make way for the true molars. As the latter teeth are very large, and the fore and aft extent of the jaw is small, there is only space for one or two of them at a time. In most of the species the last molar so much exceeds the others in size, that it occupies the entire jaw, and the other molars are shed in order to accommodate it. In the genera Tetrabelodon, Dibelodon and Mastodon, the last premolar, and the first and second true molars are isomerous, i.e. have the same number of cross-crests. In Emmenodon and Elephas they are hetero- merous; that is, the number of cross-crests successively increases from front to rear. Thus in the three genera named the ridge formula is: P.M. 2-2-8; M, 3-8-4 and P.M. ?-?—4; M. 4-4-5 or 4-5-6. In Hmmenodon the ridge formula is P.M. ?-?-?-5; M. 6—~7—6—7-8; and P.M. ?—6-7; M. 7—8-9—10-12. In Elephas the formula extends from M. 6—6—7—8-9, to M. 9-15—14-16—18-27. Hach genus then has a certain range of variation in the number of molar crests, extending from a smaller to a larger number. This successive increase in complexity has been regarded by Falconer as the index to the successive evolution of the species, and rightly so. As already remarked, however, other measures of the same succes- sion cannot be overlooked, especially as the ridge formula changes in so gradual a manner as to render it unavailable as a basis of exact divisions, as has been remarked already by Lydekker. It is evident that the primitive Proboscidea had incisor teeth in both jaws, and that these had more or less of the usual enamel investment. The gradual modifications of these features is therefore another indication of the line of descent of these animals. The primitive Proboscidea had likewise four premolars, as is now seen in Dinotherium. The successive loss of these teeth is no less an index of the evolution of the modern types of the order, than the other modifications referred to. In general, then, the phylogeny of the order may be represented thus : Elephas Emmenodon | Mastodon Dibelodon Tetrabelodon Dinotherium Primitive Proboscidea. Within each genus certain parallel modifications of the composi- tion of the crowns of the molar teeth may be observed. ‘The cross- crests may be single, or they may be divided up into tubercles. The valleys between them may be open, (1) or they may be blocked by (2) a system of single intermediate tubercles ; (3) by numerous intermediate tubercles; or (4) by the thickening of the primary tubercles. I arrange the species according to these characters. v: b, scat aia alga | Prof. E. D. Cope—On the Proboscidea. 443 TETRABELODON. : DiIBELODON. Mastopon. 1. ZT. ? brevidens. M. americanus. T. turicensis. M. borsoni. M. latidens. 2. T. angustidens. D. shepardi. M. ? cautleyr. T. productus. D. cordillerarum. MM. falconeri. T. serridens. D. tropicus. T. euhypodon. M. arvernensis. T. longirostris. 3. TZ. campester. D. humboldtii. M. sivalensis. T. pandionis. M. punjabiensis. i M. mirificus. 2M. atticus. Parallels between the species of Emmenodon and Elephas also exist. As but two species of the former genus are known, we must look for future discoveries to increase the number of correspondences. The species of both genera which approach nearest to Mastodon have a smaller number of cross-crests, which are of lesser elevation, Fic. 3.—Elephas planifrons, Fale. & Cautl. Pliocene, Siwalik Hills, India. Vertical longitudinal section of 2nd upper true molar (3 natural size). a, cement; 6, enamel ; ¢, dentine. and whose intervening valleys are occupied -by but a shallow deposit of cementum. These are the Stegodons of Falconer; (1). In the other group (2) the crests are numerous and elevated, and their interspaces are filled with cementum. EMMENODON. : SHLEPHAS. 1. £. elephantoides. . bombifrons. ganesa. . msignis. . meridionalis. . hysudricus. . antiquus, ete. It is observable that each type of molar teeth of the three genera first compared has representatives in the regions where their species occur: North America, Europe, and India. The North American species of this family are distinguished by the following characters of the molar teeth.” 1 From the American Naturalist, 1884, p. 524. 2. LE. planifrons (see Fig. 3). by by by by By by 444 Prof. EF. D. Cope—On the Proboscidea. I. Intermediate molars with not more than three crests (trilophodont). — a. Crests acute, transverse. 8. Valleys uninterrupted. Last superior molar with three crests and a heel; crests low, not serrated.—T. brevidens. Last superior molar with four crests and a heel; crests elevated, not serrated.— IM. Americanus. BB. Valleys interrupted. Edge of crest tuberculate.— 7. serridens. aa. Crests transverse, composed of conic lobes. B. Valleys little interrupted. Last inferior molar narrow, with four crests ; an accessory tubercle in each valley. D. shepard. B. Valleys interrupted. Last inferior molar with four crests and a heel ; symphysis short, M. 150; smaller size.— 7. euhypodon. : Last inferior molar with four crests and a cingulum, symphysis longer, M. 280. Size medium.— 7. productus. : Last inferior molar with five crests and a heel, symphysis very long, M. 450. Size largest.—T. angustidens. ‘aaa. Crests broken into conic lobes ; those of opposite sides alternating. Last inferior molar narrow, supporting four crests and a heel.—T7. obscwrus.’ II. Intermediate molars with four transverse crests (tetralophodont). A long symphysis ; crests well separated, tubercular, with accessory lobes inter- rupting valleys.—T7. campester. Symphysis very short; crests thick, closing valleys by contact; no accessory cusps (Leidy).—W. mirificus. III. Intermediate molars with 9-16 crests. B. Valleys filled with cementum. Last molar with 18-27 cross-crests.— Elephas primigenius. The stratigraphical position of these species is as follows :— Pleistocene. Mastodon americanus, Elephas primigenius (less abundant). Pliocene. Elephas primigenius (more abundant.) Tetrabelodon serridens (horizon probable). Dibelodon shepardi Upper Miocene (Loup Fork). Tetrabelodon euhypodon. 55 productus. 3 angustidens. 50 campester. Mastodon mirificus. Ticholeptus bed. Tetrabelodon brevidens.”’ Prof. Cope then proceeds to give an account of the American species, M. (Tetrabelodon) obscurus, Leidy, M. (Dibelodon) Shepardi, Leidy; the latter of which is from the Pliocene of the valley of Mexico. M. (Tetrabelodon) brevidens, Cope, is the oldest North American species, and presents a very simple type of molar: it is from the Ticholeptus bed of Montana. M. Tetrabelodon angustidens, Cuv., occurs in the Loup Fork beds of Kansas, Nebraska, and Dakota. The molar teeth exceed in size those of the typical European form. “It may become necessary,” says Prof. Cope, ‘to distinguish this form as a species under the name of Teérabelodon proavus.” ‘The author adds that, ‘ Probably this species has been Prof. E. D. Cope—On the Proboscidea. 445 recorded by Whitfield from the Phosphate beds of South Carolina, and compared with M. obscurus.” A figure of the European form is given on p. 447, Fig. 6. M. (Tetrabelodon) euhypodon, Cope, is also from the Loup Fork beds of Kansas, and is known by a nearly perfect left mandibular ramus, with last molar tooth and tusk, and an entire palate with both last molar teeth and tusks. “The superior tusks,” says Cope, ‘‘are compressed distally, and the inferior tusks are large and have an enamel band; they are cylindric.” M. (Tetrabelodon) productus, Cope, is abundant in the Loup Fork beds of New Mexico; it is the only species in which three upper pre- molars have been demonstrated ; other species having generally two. M. Tetrabelodon campester, Cope, is a rather large species, with a very long symphysis of the lower jaw and a low ramus. It is in some measure allied to M. (T.) longirostris of Europe, but the symphysis is longer and the teeth more complex. ‘This species is also from the Loup Fork beds of Kansas and Nebraska. M. (Dibelo- don) Shepardi, Leidy, was founded on an inferior sixth molar from California. Cope subsequently described other specimens from the Pliocene of Mexico, where it is abundant. IM. (Tetrabelodon) serri- dens, Cope, was founded on a first or second true molar from Texas. It is peculiar among American species in its acute, elevated, entire crests with tuberculo-serrate edges. Mastodon mirificus, Leidy, is known from a left ramus of a lower jaw which supports the last molar. Its symphysis is short and acute. “ Mastodon Americanus, Cuv., is the best known and latest in time of the American elephants. It is one of the largest species, and, after T. brevidens, possesses the simplest molar dentition. The symphysis of the lower jaw is short and decurved. The skull is wider and less elevated than that of the Mammoth, and the tusks are shorter and less recurved. It was very abundant during the Pleistocene age throughout North America, from ocean to ocean, and as far south as Mexico; but it has not been found in the latter country. Its remains are usually found in swamps, in company with recent species of Mammalia, and with Equus fraternus and Bos latifrons, 'The carbonaceous remains of its vegetable food have been found between its ribs, showing that, like the Mammoth, it lived on the twigs and leaves of trees. It is at first sight curious that this, the simplest of the family of Elephants in the characters of its molar teeth, appears latest in time on this continent. But it must be regarded as an immigrant from the Old World, where an appropriate genealogy may be traced. Its nearest ally, Mastodon borsonii, existed just anterior to it, during the Middle and Upper Pliocene, and this species was preceded in turn in the Middle and Upper Miocene by the T. turicensis, which possesses the same simplicity of the molar teeth. In its mandibular tusks the latter possesses another primitive character which was nearly lost by its North American descendant.” — “ Hlephas primigenius, Blumenbach, ‘the Mammoth,’ was at one time distributed throughout North America, as far south as the valley of Mexico inclusive. Its remains are found in the Upper a a 446 Prof. E. D. Cope—On the Proboscidea. Pliocene of Oregon, and in the Pliocene of Mexico, unaccompanied by the Mastodon americanus, which had not appeared by that time. In the Eastern States its remains occur with those of the Mastodon = = Zs Fig. 4 —Elephas primigenius, Blum., the third left upper true molar; dredged off the Dogger Bank, North Sea (one-third nat. size). ‘The lower border of the figure is the inner border of the specimen. Original in British Museum (Nat. Hist.). americanus at the Big Bone Lick, in Kentucky. It was not found in the Port Kennedy, Pennsylvania, Bone-fissure, although the Mastodon was there. This absence may be accidental. Leidy says,’ The animal (Klephas primigenius americanus) was probably of earlier origin, and became earlier extinct than the Mastodon, an opinion which my own observations confirm. Since no earlier species of Hlephant proper is known from North or South America, we must regard this one as an immigrant from Asia, where, indeed, its remains abound. It remained longer in Siberia than in North America, since whole carcasses have been discovered imprisoned in the ice, near the mouth of the river Lena. These specimens had a covering of long hair, with an under layer of close wool. Leidy and Falconer have observed that the teeth of the Elephants from eastern North America can be easily distinguished from those of the Mammoth by the greater alternation of the enamel plates. Leidy also observes that the lower jaw is more acuminate in the former. He proposed, therefore, to distinguish it as a species, using Dekay’s name &. americanus. ‘Teeth from Escholtz Bay, Alaska, he regards as belonging to the true Z. primigenius. Falconer regarded the true Elephant of Texas as a distinct species, which he named &. columbi. He distinguished it by the coarse plates of the enamel, and by the wide lower jaw, with curved rami, and short symphysis. So far as the dentition goes, I have specimens of this type from Colorado and from Oregon. The Oregon specimen presents the same type of lower jaw as does one from Texas, in my possession. Specimens from the valley of Mexico are abundant in the museums of the city of Mexico, and their characters do not differ from those from Texas. I have in my museum an entire skull, lacking the lower jaw, from the ‘ orange sand’ of the city of Dallas, in north-eastern Texas, which only differs in form from that of the LE. primigenius, as figured by Blumenbach and Cuvier, in the shorter and wider premaxillary region. This is one-half wider than long (from the molar alveolus), while in the Ilford Mammoth in the 1 Extinct Mammalia of Dakota and Nebraska, p. 398. Ls Prof. E. D. Cope—On the Proboscidea. AAT Forms or SKULLS AND SKELETON oF PRoBoscIpDEA. 448 A. S. Woodward—British Jurassic Fishes. British Museum, figured by Leith Adams;,! the length of this region equals the width. The skull agrees with those of HE. primigenius, and differs from those of H. indicus in the narrow proportions of the posterior part of the cranium. The teeth are of the coarse- plated HE. columbi type. The individual is not very large, though old. The diameter of the tusks at the alveolus is 110mm. Ina fragment of a huge specimen from south-western Texas, the diameter of the tusk at the base is 210 mm. As a result it is not clear that the two American forms can be distinguished as yet from the Hlephas primigenius, or from each _ other, except as probable sub-species, H. p. columbi, and E. p. ameri- canus. But more perfect material than we now possess may yet enable us to distinguish one or both of these more satisfactorily. No American species of the family exceeded this one in general dimensions, especially the form E. p. columbi.” EXPLANATION OF PLATE XIII, Forms or PrososcipEan Monars. Fic. 1.—Hlephas (Emmenodon) Cliftii, Falconer & Cautley. ‘The first (?) left upper true molar in an early stage of wear; from the Siwaliks of Burma (4 nat. size). The lower border of the figure is the inner border of the specimen. (The original preserved in the Museum of the Geological Society of London.) Fic. 2.—Elephas antiquus, Falconer. The first left upper true molar in a half worn condition; from the Pleistocene of Grays, Essex (# nat. size). The lower border of the figure is the inner border of the specimen. (Original preserved in the British Museum, Natural History.) Fie. 3.—Wastodon latidens, Clift. The third left upper true molar of a small individual in a partially-worn condition: from the Pliocene of Borneo (2 nat. size). The lower border of the figure is the inner border of the specimen. EXPLANATION oF FicurES upon PacE 447. Forms of Skulls and Skeleton of Proboscidea. Fie. 5.—Elephas ganesa, Falconer & Cautley. Profile of the skull; from the Siwalik Hills (ss nat. size). [After Gaudry.] The original preserved in the British Museum (Natural History). Fie. 6.—WMastodon (Tetrabelodon) angustidens, Cuvier. [After Gaudry.] Middle Miocene, Sansan (Gers), France. The entire skeleton restored and greatly reduced. Fic. 7.—Elephas planifrons, Fale. & Cautl. Profile of skull restored ; from the Pliocene of the Siwalik Hills (45 nat. size). [After Gandry. ] Fie. 8.—Wastodon sivalensis, Cautley. Profile of skull restored ; from the Pliocene of the Siwalik Hills (5 nat. size). [After Gaudry. ] Tl].—Pretiminary Nores on some NEW AND LITTLE-KNOWN BriTIsH JuRASSIC FisHEs.? By A. Smirx Woopwarp, F.G.S., F.Z.S., Of the British Museum (Natural History). INCE the works of Agassiz and Egerton, few contributions have been made to the knowledge of British Jurassic ‘‘ Ganoid” and “‘Teleostean” Fishes, and a considerable amount of undescribed material has thus accumulated in various collections. Much more progress has been made upon the Continent, where the Lithographic 1 Mon. Pal. Soc. 1879, Brit. Foss. Elephants, p. 69, pl. vi. and vii. 2 Read betore Section C (Geology), British Association, Newcastle, Sept. 1889. A.S. Woodesaid=2 British Jurassic Fishes. 449 Stones of Bavaria, Wirtemberg, and Ain, especially, yield a rich assemblage of forms in a remarkable state of preservation; and it is now an interesting study to compare the British Jurassic fossils with their well-known continental allies. Such an undertaking is facilitated by the recent appearance of Prof. Dr. K. A. von Zittel’s admirable critical summary of the extinct Mesozoic fishes;* and it is the object of the present notice to offer some preliminary remarks upon a few of the more prominent types observed by the author in English collections. 1. Eurycormus grandis, sp. nov. In 1863, A. Wagner” described a genus of fishes from the Litho- graphic Stone of Hichstaidt, Bavaria, under the name of Hurycormus, making known a single species, EH. speciosus; and in 1887, Prof. v. Zittel added some supplementary information to the original diagnosis, while publishing detailed figures of the vertebrae. No precise particulars, however, concerning the cranial osteology and dentition have hitherto been forthcoming; and the recent discovery by Mr. Henry Keeping, in the Kimmeridge Clay of Ely, of a fine head of Hurycormus, not only makes known the occurrence of a new species of the genus in England, but reveals structural features of considerable taxonomic significance. ‘The specimen is preserved in the Woodwardian Museum, Cambridge, and the author is indebted to the kindness of Prof. McKenny Hughes, F.R.S., for the oppor- tunity of undertaking a detailed study of its characters. The skull, jaws, and opercular apparatus agree precisely in general form and proportions with the corresponding parts figured in Wagner’s typical species, while two anterior vertebra exhibit the characters assigned to them by v. Zittel. The Ely species, however, is nearly three times as large as the Bavarian form, and differs (according to Wagner’s description) in the superficial tuberculation of several of the head-bones ; it may therefore receive the distinct specific name of Hurycormus grandis. 'The maxilla is narrow, and its arched margin is provided with a single close series of small slender teeth ; the vomerine or palatine bones (or both) bear a cluster of similar teeth of larger size; and the inner side of the mandible seems to be constituted by the splenial element, provided with at least one series of small teeth, while for a short space near the anterior end of each dentary are observed the sockets of about nine large teeth. Hach dentary bone is deep and plate-like, and, though much crushed, doubtless inclined inwards in its inferior half; and a very large elongated azygous jugular plate extends between the rami as far back as the suture between the dentary and angular elements. The hyomandibular bone is more lamelliform than in Pachycormus, etc., thus more nearly resembling the same bone in Caturus, the Lepto- lepide, and modern Teleosteans. 1 “ Handbuch der Palzontologie,” vol. iii., pts. i. ii. (1887-88). * A. Wagner, ‘‘ Monographie der fossilen Fische aus den lithographischen Schiefern Bayerns,”’ Abh. k, bay. Akad. Wiss., cl, ii. vol. ix. (1868), p. 707, pl. iv. DECADE IlI.—VOL. VI.—NO. X. 29 450 A. 8. Woodward—British Jurassic Fishes. 2. Strobilodus suchoides, Owen, sp. An examination of the type-specimen of Strobilodus giganteus, Wagner,’ in the Munich Museum, has convinced the present writer of its generic identity with the so-called Thlattodus suchoides, Owen,? as already suggested with hesitation by v. Zittel (loc. cit. p. 229). One more Bavarian type is thus added to the fish-fauna of the English Kimmeridge Clay ; and, as will shortly be pointed out else- where, there is evidence of still another British species of the same genus ranging as far upwards as the Purbeck Beds (Brit. Mus. 46,911). 3. Hypsocormus Leedsi, sp. nov. The genus Hypsocormus was founded by Wagner in 1863,? and, as remarked by v. Zittel, only two species are yet recognized, these being apparently confined to the Bavarian Lithographic Stone. Characteristic portions of the jaws of two other species, however, have been discovered in the Oxford Clay of Peterborough, by Mr. Alfred N. Leeds, of Eyebury, who has kindly entrusted them to the present writer for elucidation; and although the dentition of the genus has not hitherto been described in detail, the recent acquisition by the British Museum of a fine example of Hypsocormus macrodon from Solenhofen, renders a direct comparison of actual specimens possible. The larger species from Peterborough, which may be appropriately named H. Leedsi, is represented by the anterior extremity of the snout associated with two fragments of the skull (No. 39, Leeds Coll.), indicating as large a fish as H. macrodon. The snout is obviously a compound bone, but the discussion of the homologies of its parts may be deferred. As in the Solenhofen species just mentioned, it is obtusely pointed, the two sides meeting approximately in a right angle at its anterior termination ; and the external surface is finely granulated. As in H. macrodon, also, there is a pair of large tusk-like teeth, rounded in section, arising from sockets in the middle of the bone; but, whereas in the species just referred to, these ‘‘ tusks” are directed vertically downwards, in H. Leeds they are much inclined forwards, and, if perfect, would doubtless project beyond the front of the supporting bone. An irregular cluster of small, stout, conical teeth occurs on each side of the central pair, and two of these outer teeth, larger than the others, are placed directly in front. The abraded anterior extremity of a large right mandibular ramus of Hypsocormus in Mr. Leeds’ collection (No. 388) also probably pertains to H. Leedsi, corresponding to the above-described snout in size ; and this fossil is interesting as exhibiting the form and pro- portions of the splenial element. The dentary constitutes the outer 1 A. Wagner, ‘‘ Beitr. Kennt. lith. Schief. Fische,’’ Abh. k. bay. Akad. Wiss., cl. ii. vol. vi. (1851), p. 75, pl. i. * R. Owen, ‘‘ On a Genus and Species of Sauroid Fish (Zhlattodus suchoides, Ow ) from the Kimmeridge Clay of Norfolk,’? Grou. Mac. Vol. III. (1866), pp. 55-57, Tels JOO 3 A. Wagner, doc. cit. (1863), p. 677. A. 8. Woodward—British Jurassic Fishes. 451 side of the jaw and exhibits the abraded remains of a series of teeth, of moderate size, firmly implanted in sockets; while the splenial is a short, stout, lenticular bone, perhaps entering somewhat into the symphysis, but having its thickest portion immediately behind, supporting two great rounded tusks, in sockets, accompanied in front and behind by an irregular cluster of relatively minute stout conical teeth. 4. Hypsocormus tenuirostris, sp. nov. The second species of Hypsocormus in Mr. Leeds’ collection is represented by an imperfect snout, associated with a right maxilla and portions of splenial and dentary bones (No. 40). The original fish must have attained only about half the size of the typical speci- men of H. Leedsi; and it is readily distinguished by the narrow, somewhat elongated, and acutely pointed form of the snout, which, however, exhibits the characteristic superficial granulations. The pair of tusk-like teeth is placed relatively further backwards than in H. macrodon and H. Leedsi, and seems to have been directed more nearly vertically than in the latter species; so far as can be ascertained, a single irregular series of teeth of small size also occupies the margin of either side, being accompanied only by few minute teeth. The maxilla is very slender, externally tuberculated, and provided with a single series of teeth of moderate size, well- spaced and nearly uniform, and flanked externally by a few minute teeth; the anterior end of the bone terminates in a stout, smooth projection, slightly directed inwards. The portions of dentary bones are somewhat broken, but this element is stouter and larger than the maxilla, provided with a single spaced series of much larger teeth, irregular in size, the most powerful being situated in the front portion of the posterior half of the bone; a cluster of minute teeth also occupies the whole of the external margin. As in the other species of Hypsocormus, all the teeth are oval or round in section, not keeled, though more or less vertically striated ; and the enamelled apex often occupies less than half of the exserted portion. So far as can be ascertained from the foregoing specimens, there is a singular resemblance between the dentition of Hypsocormus and that of the long-snouted Protosphyrena of the Upper Cretaceous. In the last-named genus there are two great upper teeth at the base of the snout,’ while two equally large teeth occur on either side of the lower jaw near its anterior extremity; the latter, moreover, are similarly fixed in a short stout, lenticular splenial bone immediately behind the mandibular symphysis.’ It may be added that the genus Hypsocormus also occurs in the Kimmeridge Clay of Weymouth, portions of jaws being preserved in the British Museum (No. 42,368). 5. Leedsichthys problematicus, gen. et sp. nov. For some years Mr. Alfred N. Leeds, of Eyebury, has obtained 1 W. Davies, Gzor. Mac. Dec. II. Vol. V. (1878), Pl. VIII. Fig. 3. 2 F. Dixon, ‘Geol. and Foss, Sussex’? (1850), pl. xxxi. fig. 12. 452 A. S. Wooduward—British Jurassic Fishes. from the Oxford Clay of the neighbourhood of Peterborough a number of large bones of fibrous texture, and often of indefinite form, pertaining to some hitherto unknown extinct vertebrate. The _ flatter bones were considered by Mr. Hulke, in 1887, as not improbably referable to the dermal armature of a Dinosaur ;1 but, on visiting the collection in 1888, Prof. Marsh expressed the opinion that the remains were piscine, being unlike any of the numerous types of Dinosaurian dermal armour met with in America. At the beginning of the present year,? the writer of this note mentioned the possibility of these fossils indicating the presence of a large Acipen- seroid fish in the Upper Jurassic rocks; and it is proposed in the following pages briefly to discuss the few facts already available for consideration. One set of bones undoubtedly pertains to a single individual, and is thus of great value; but many of the fragments are scattered, and, if the interpretations now to be suggested prove correct, the axial skeleton of the trunk still remains to be dis- covered. No known specimens exhibit any traces of superficial ornamentation, and, though often massive, all the elements have the characteristic fibrous texture of fish-bone. The associated series of bones just mentioned was spread over an area of probably not less than twelve square yards, and the principal specimens may be enumerated and determined as follows: 1. A large, oblong, flattened bone, of the kind already described by Mr. Hulke. It measures 2 ft. (0°61 m.) in length by 1 ft. din. (0°38 m.) in maximum breadth, is of a squamous character, thinning at each margin, and consists of two thin hard layers separated by a middle layer of soft diploé. In form and characters the bone is very suggestive of a frontal element. 2. An elongated bone, 1 ft. 8in. (0°58m.) in length, somewhat broader at one extremity than at the other. One long margin is thickened and rounded, while the other is a thin edge; and the broader extremity is thicker than the narrower. This may perhaps be identified as angular. 8. An elongated bone, 1 ft. 3in. (0°38 m.) in length, and the broader extremity of the corresponding element of the opposite side. This is probably the hyomandibular. The supposed upper extremity is somewhat expanded, and near this end on the posterior outer margin is a small facette, evidently for the operculum. For two- thirds of its width the bone is thick, but the anterior third is thin, as is also the inferior extremity. 4. Portions of four long narrow bones, the largest being 2 ft. din. (0-785 m.) in length, and not more than 384in. (0-09 m.) in maximum width. Each bone is comparatively hard, irregularly ~<-shaped in transverse section, and seems most nearly paralleled by the ossifications of the branchial arches in Teleosteans. 5. A very large number of small, narrow, elongated bones of peculiar shape, probably to be regarded as giil-rakers. The largest 1 J. W. Hulke, ‘‘Note on some Dinosaurian Remains in the Collection of A. Leeds, Esq.,” Quart. Journ. Geol. Soc., vol. xliii. (1887), p. 702. * Smith Woodward, ‘‘On the Paleontology of Sturgeons,’’? Proc. Geol. Assoc., vol. xi. (1889), p. 81. A. 8. Woodward—British Jurassic Fishes. 453 of these are about 3in. (0-075 m.) in length, and 4in. (0-010m.) in width. Hach is laterally compressed, slightly expanded at one extremity, and rarely straight, but irregularly bent or contorted. The surface is coarsely rugose, and one long border is rounded, while the other is cleft by a longitudinal median furrow. The rounded border is comparatively smooth, but the furrowed edge is coarsely serrated, a series of short oblique ridges terminating in points on each side. 6. Portion of a large squamous bone, longer (deeper) than broad, with one long margin thickened, rounded, and concavely arched. A nearly complete example of the same element, doubtfully forming part of the series, measures 2ft. 9in. (0°838m.) in length, and suggests that it may be identified either with the preoperculum or clavicle. 7. Portions of eleven very dense, large, rib-shaped bones, only superficially ossified at the broader extremity, but terminating in a well-formed point at the distal end. These bones are rounded or irregularly quadrangular in section, are more or less arched, and vary considerably in relative width or thickness. The broadest and stoutest specimen is much arched, 1 ft. 5in. (0°48 m.) in length; and a nearly perfect detached example of the same bone shows that this wants a length of at least Sin (0:23m.) at the pointed extremity. The largest bone measures 2ft. 4in. (0°712m.) in length, and is straightened ; while the smaller examples are more curved and more rounded in section. These bones were evidently arranged in not less than six pairs, and Mr. Leeds’ suggestion seems most plausible, that they are the branchiostegal rays of the fish. 8. The fin-rays are most remarkable, and, judging from the position in which they were discovered, the known specimens may all probably be assigned to the pectoral fin. They consist of fibrous bone, and appear as if composed of numerous long, tapering bony splints, incompletely fused together. 'The two halves of each ray remain separate, and in some cases they have been proved to attain a length of not less than 5ft. (1:525m.). There are no transverse joints, but all the rays exhibit numerous bifurcations, and Mr. Leeds estimates that the distal extremity of each of the largest becomes divided into at least thirty-two small branches. Smaller more slender fin-rays, probably of the same type of fish, have also been discovered in the Oxford Clay of the same locality. These are gently rounded and transversely articulated, thus suggest- ing that the specimens just noticed are characteristic only of a powerful pectoral. As already mentioned, many other detached bones, undoubtedly of the same genus and species, occur in Mr. Leeds’ collection; but, of the elements not described above, the form is so indefinite as to render their determination very uncertain. If, however, the few suggestions here propounded are eventually confirmed, it is obvious that many hard parts of the fish still remain to be discovered. No known fish with ossifications of the branchial arches and branchi- ostegal membrane of the kind here described is destitute of at least some ossifications in the axial skeleton of the trunk; and it will be strange, indeed, if a monster with such powerful pectoral fins does 454 A. S, Woodward—British Jurassic Fishes. ; not prove to have been possessed of a formidable dentition. It is satisfactory to know that there is good reason to hope for the dis- covery of much more of the skeleton of the individual discnssed above, as soon as the bed where it occurs is worked again; and Mr. Leeds is fortunately acquainted with the precise stratum where the specimen occurs. The characters of the gill-rakers, branchiostegal rays, and pectoral fin-rays, taken together, justify the definite separation of the fish in question from all known generic types; and it is proposed to apply to it the name of Leedsichthys in honour of its discoverer. The Peterborough species may be provisionally termed Leedsichthys problematicus, and it is probably the most gigantic Jurassic fish hitherto described. A group of the characteristic gill-rakers, of equally large size, has also been obtained from the Oxford Clay of Vaches Noires (Brit. Mus. No. 32,581), thus indicating the occurrence of the genus in the Upper Jurassic of the North of France. 6. Mesodon. The genus Pycnodus, as now defined, is restricted to the Eocene formations, and all the British Mesozoic fossils originally described under that name are to be distributed among the more precisely defined genera determined on the continent. This is a difficult task, so far as the Jurassic species are concerned, for little more than detached examples of jaws and teeth are known, and there is appar- ently considerable variation in these parts. The so-called Pycnodus pagoda, Blake,' fiom the Portlandian, is evidently a vomer of Micro- don; but nearly all the other described British Jurassic “ species ” of Pycnodus pertain to Mesodon. Fricke, v. Zittel, and others, have already pointed out that to this genus may be referred the Agassizian species P. Buckland, P. ovalis, and P. rugulosus, and to the synonymy of the first we would add P. didymus, Ag., P. obtusus, Ag., and Gyrodus perlatus, Ag. The latter name is given to some detached scales from the Stonesfield Slate, ornamented by tubercles instead of rugosities or pits, thus being truly referable to Mesodon, and agreeing sufficiently in size with the associated jaws of M. Bucklandi to be provisionally ascribed to that form. To M. rugulosus we would also assign the undescribed Pycnodus parvus, Ag., of which a specimen marked as “type” is in the Egerton Collection. Some so-called species of Gyrodus, e.g. G. trigonus, Ag., are also most probably referable to the same genus; and the Liassic Pycnodus liassicus, Kgert., was long ago placed in Mesodon by Heckel. 7. Thrissops. Since the researches of Agassiz, Miinster, Wagner, and Thiolliére, so many Jurassic examples of the genus Thrissops have been acquired by various Museums. that it would be interesting to study the characters of the specific types already determined in the light of the new material before making any further additions to the 1 J. F. Blake, “On the Portland Rocks of England,’’ Quart. Journ. Geol. Soc., vol, xxxvi. (1880), p. 228, pl. x. fig. 10. P. G. Sanford—Analysis of Fullers Earth. 455 nomenclature of the group. In recording the occurrence of the genus in the English Jurassic, it must therefore suffice to remark that the British Museum possesses characteristic remains of a species as large as T. Heckeli, Thioll.,! from the Kimmeridge Clay of Dorsetshire (B.M. Nos. P. 922, P. 3686, P. 6031); while a nearly complete example of a much smaller species has been obtained from the Portland Stone of the Isle of Portland (B.M. No. P. 5538). 8. Browneichthys ornatus, gen. et sp. nov. In the series of vertebrate fossils from the Lower Lias of Barrow-on-Soar, recently obtained for the Leicester Museum by Mr. Montagu Browne, F.Z.S., is an interesting small fish, apparently of a new generic type, which the present writer has been favoured with the privilege of examining. The specimen is only about 0:06 in length, displaying portions of the head and trunk; but, notwithstanding its imperfections, it seems worthy of brief notice as being so different from anything hitherto known. The fish must have been originally elongated in form; and the hinder portion of the head, preserved as far forwards as the front margin of the orbit, suggests the attenuation of the snout. The space occupied by the notochord is vacant, indicating its persistence, but the neural and heemal arches are well ossified superficially, and there is no evidence of elongated, well-developed ribs. The bones of the head are invested with ganoine, and ornamented with large tuberculations ; and at least the front portion of the trunk is covered with thin, deeply-overlapping scales, oval or round in shape, with prominent concentric lines of growth, and externally ornamented with large ganoine tubercles. Three or four relatively large, narrow, pointed ridge-scales, above and below, also indicate a partial or continuous armature of the dorsal and ventral margins. Of the dentition and the fins, nothing can be ascertained from the fossil now described ; and although a series of eight slender bones shortly behind the occiput may possibly be the interspinous bones of a dorsal fin, it will be well to await the discovery of other specimens before attempting their interpretation. So far as can be determined, the new Barrow fossil thus most nearly approaches the early Mesozoic Ganoids, Belonorhynchus and Saurichthys. From these, however, and from other types with a persistent notochord, it is generically distinguished by the squama- tion; and employing the discoverer’s name, the new form may be termed Browneichthys. The type-species may be known as J. ornatus. IV.—An Awnatysts oF THe Futuers Harta or NutFieLp. By P. Greraup Sanrorp, F.I.C., F.C.S., Royal School of Mines, London. URING June last I visited the Fullers Earth Pits at Nutfield, near Redhill, Surrey, with the London Geological Field Class, when Professor Seeley suggested to me that I should make an 1 VY. Thiolliére, ‘‘ Poiss, Foss. Bugey,”’ pt. i. (1854), p. 27, pl. x. fig. 1. 456 =P. G. Sanford—Analysis of Gault and Greensand. analysis of the deposit. This I have been enabled to do throngh the kindness of the manager (A. Sheridan, Esq.), who was good enough to send me a series of samples of the earth, and the various products prepared from it. The Nutfield Fullers Earth is a heavy blue or yellow clay, with a greasy feel and an earthy fracture. The sample No. 1 contained 27-47 per cent. and No. 2, 29:56 per cent. of water before drying. No. 1. Buue Earrs. Dried at 100° C Insoluble Residue. Insoluble Residue = 59°96 per cent.= (SiO, = 452-81 per cent. Tron (Fe203) = | Dente) INGO A = PEGs A Alumina (Al,03) =—oitG \Fe,0; = 1:30 ,, Lime, CaO Sy CaO — 7 coo mmeny Magnesia, MgO = 1-41 (Ngo = O88, Phosphoric acid, P20, = 0°27 \ Soluble os Sulphuric acid, SO; = 0-°04/ im acid, 59-96 Sodic chloride, NaCl = 0:05 Alkalies, K.0 — 0-74 Combined water = 14:27 No. 2. YreLtow Earra. : Dried at 100° C Insoluble Residue. Insoluble Residue = 76:18 per cent.= {Silica = 59°37 per cent. Tron, Fe203 Soke AlO, = 10°05 ,, Alumina es alsyr7 Fe.03 = 3°86 ,, Lime, CaO = 4:31 CaO elt OMe Magnesia, MgO = 1:05 MeO = teres BOZ = 0°14\{ Soluble —- S03 = 0-°07/ in acid. 76°18 Salt, NaCl = 0-14 Alkalies, K,O = (Oss Combined water =P sag 100-05 V.—ANALYSIS OF THE GAULT AND GREENSAND. By P. Geraxtp Sanrorp, F.I.C., F.C.S., Metallurgical Laboratory, Royal School of Mines. HE sample of Gault, of which the analysis is given below, was obtained from the Clay Pits at Dunton Green, which I visited with the “London Geological Field Class” during June last. At this place the Gault rests upon a bed of reddish yellow sand (Lower Greensand), which is mixed in certain proportions with the Gault clay to form bricks. This sand, of which I also give an analysis, is very moist when first taken from the bed, but very rapidly becomes dry, upon exposure to the air, so that it afterwards loses very little more water at 100°C. The Gault, as taken from the pit, contained 26:68 per cent of moisture, but upon ignition of the dried substance, in a muffle furnace, it becomes so hard that it will scratch glass easily. Notices of Memoirs—D. Stur—On British Ooal-plants. 457 ANALYSIS OF GAULT. Dried at 100°C, Insoluble Residue. Insoluble Residue = 65°01 per cent = (Silica, SiO, = 46°43 per. cent. Ferric oxide, Fe,O3 = 7°92 Fe.03 = 2°05 55 Alumina, Al,03 0 seAD Al,0, ieee ee Maganese oxide, MnO. = trace CaO = 0°88 8 Lime, CaO = 5°90 MgO = 0:24 Als Magnesia, MgO = 0°75 = Sodium chloride = 0°05 + Soluble 65°01 Phosphoric acid, P20, = 0-11 | im acid. == Sulphuric acid, SOs = 0:19 Carbonic acid, CO, = 6:09 K20, ‘and Nas,O = 0:07 Combined water = 10-48 99-97 ANALYSIS OF GREENSAND. Dried at 100°C. \ Silica, SiO. ... 98°80 per cent. Fe,03 + Al,03 0°47 Lime, CaO Magnesia, MgO 0°05 - Soluble in acid. inno S S ite) Sulphuric acid,SO3;= trace Combined water 0°42 99°83 INFCwBstOeS) (Ose Mirai @ab eS - D. Stur on British Coat-Puants. T.—Momentaner STANDPUNKT MEINER KENNTNISS UBER DIE STEINKOHLENFORMATION HENnGuanps. Von D. Srur. Jahrbuch der k. k. Geolog. Reichsanstalt, 1889, Ba. xxxix. [uy 2) Heft: pp. 1-20. ERR D. STUR, the Director of the Geological Survey of Austria, took advantage of his visit to the International Geological Congress last year, to study in the field and in some of the principal museums, the flora of the British Carboniferous strata, and the present paper contains in a condensed form the results of his observations and his views of the relative age of our different coal- fields, as compared with the beds on the Continent, and more particularly with those of the Moravian-Bohemian-Silesian area. The following are the conclusions arrived at by the author :— I. In Britain, the first or oldest Culm-flora of the Culm-roofing shales, specially occurs in the great Scotch basin, in the Burdie- House limestones, in the Carboniferous shale of Slateford, and in the Calciferous sandstone. In Devonshire, on the other hand, the Culmdackschiefer is represented by the “ Lower Culm- measures ’ near Bideford, whilst the “ Upper Culm-measures” belong to the Lower Carboniferous, and are identical with the Schatzlarer beds. II. The second Culm-flora, or that of the Ostrauer beds, is probably quite absent in England, and not a single characteristic species was 458 Notices of Wemoirs—D. Stur—On British Coal-plants. met with. It is probable that the great band of the Millstone-grit, which in the Pennystone and Barnsley district is beneath the horizon of the Schatzlarer beds, may represent the Ostrauer deposits, and in this case the second Culm-flora might be looked for in the thin Coal- seams occasionally occurring in the Millstone-grit. It is further possible that the Coal-measures of the Scotch basin may correspond with the Silesian Ostrauer beds. III. The greater part of the coals obtained in England are from the horizon of the Schatzlarer beds. To this horizon belong the Coal-areas of Newecastle-on-Tyne, Leeds, Pontefract, Barnsley, Sheffield, Derby, Leicester, Dudley, Coalbrook-Dale, Newcastle- under-Lyme, Manchester, Oldham, Lancaster, and of Whitehaven and Wigton. IV. The Upper Carboniferous horizon of the Bohemian Rossitzer beds occurs in England in the area of the Bristol Channel, near Bristol and Radstock, and in the vicinity of Merthyr Tydvil, over Swansea to Caermarthen; and more to the north the Coal-fields of the Forest of Dean, the Forest of Wyre and near Wigan, belong to this same Upper Carboniferous horizon. V. It is remarkable that up to the present no trace of the presence of this Upper Carboniferous horizon has been met with to the east of the great band of Millstone-grit, and in this respect there is a striking correspondence with the Coal-fields of Westphalia, Belgium and Northern France, which belong to the Schatzlarer horizon, and in which the Upper Carboniferous Rossitzer beds are not represented. VI. The Upper Carboniferous, on the other hand, occurs in Central France, Bohemia and Saxony, also in Banate, and frequently unconformably on much older strata. Thus, also in the line from Swansea, Bristol, Forest of Dean to Shrewsbury the Upper Carbon- iferous beds are in places unconformably deposited on older strata. VII. Further, there is in England no trace of the horizon of the Schwadowitzer beds of north-eastern Bohemia, of the Saxon beds of Oberhohndorf near Zwickau, nor of the Radnitzer and Zemech beds. These horizons may probably be looked for where the beds of Schatzlarer approach those of the Upper Carboniferous, as at Wigan and at Coalbrook- Dale. VIII. It may be concluded from the absence of particular beds in the Carboniferous series of England, France, Belgium and West- phalia, that great changes in the configuration of the land took place during the deposition of the Coal and its associated beds ; that they were by no means continuously laid down; and that the changes in the flora of the individual horizons indicate enormously prolonged intervals of time for their production. The author further adds short critical notices of the more important species of fossil plants in the Hutton Collection, now preserved in the Museum at Newcastle-on-Tyne. Reviews—Dr. W. Dames—The Triassic Ganoids. 459 IJ.—Tur Grotocy or Lonpon AND oF Part oF THE THAMES VALLEY. By Witiram Wuitaker, F.R.S. [peace the above title there has just been published a Geological Survey Memoir (in two volumes), which gives a very full and detailed account of the geology of the district. Vol. i. Descriptive Geology, pp. xii. 556, folding table, price 6s.; and vol. ii. Appen- dices (well-sections, etc.), pp. iv. 852, price 5s. We hope in a future number, after H.M. Government has presented us with a review- copy, to give some account of this important work, which, to say the least of it, offers a large amount of material for study and for reference at an unusually low (official) price. Ee, 2Ey) Vie sea Vi = Tue Ganorps oF THE German MuscHELKALK. “Dik GANOIDEN DES DEUTSCHEN MuscuetKauks.” By Prof. Dr. W. Damss. Paleontologische Abhandlungen, Band IV. Heft 2 (1888), pp. 133-180, pls. xi—xvia. O any one accustomed to the writings of Agassiz, Count von Minster, H. von Meyer, and others, upon the fossil fish remains of the Muschelkalk, Prof. Dames’ memoir will come as a pleasant surprise. Instead of a series of scattered teeth and scales, the Pro- fessor has brought together from various museums a number of valuable specimens affording some real insight into the characters of the Mid-Triassic Ganoids ; and the detailed descriptions and discussion of these fossils are illustrated by seven fine plates. The specimens were almost exclusively obtained from the extra-Alpine Muschelkalk, and are referable to the genera Gyrolepis, Agassiz ; Colobodus, Agassiz; Crenilepis, Dames; and Serrolepis, Quenstedt. The reference of Gyrolepis to the Paleeoniscide is confirmed by several fine fossils, and a definition of the genus can at last be attempted. The mandibular suspensorium is very oblique, and the operculum extremely elongated vertically ; the teeth are long, slender, and conical; the dorsal fin is smaller than the anal, and situated opposite or in advance of this; there are small fulcra upon each of the fins; most of the pectoral fin-rays are not articulated; and the two infraclaviculars are fused together. This genus is the only Paleoniscid yet described from the European Trias, and Prof. Dames recognizes four species, as follows: G. Agassizii (Minster), and G. ornatus (Giebel), from the Lower Muschelkalk, G. Albertii, Agassiz, from the Upper Muschelkalk, and G. Quenstedti, Dames, from the Lettenkohle. Gyrolepis Agassizit has until now been assigned either to Ambly- pterus or Rhebdolepis; but a comparison of the well-preserved type- specimen with more recently discovered examples of Gyrolepis proper definitely decides its generic position, and the characters of the scale- ornament determine its specific distinctness. G. ornatus has also been hitherto referred to Amblypterus, and the type-specimen, now figured for the first time, remains unique. G. Alberti is no longer 460 Reviews—Dr. W. Dames—The Triassic Ganoids. known merely from detached scales, but is represented by the anterior portion of a fish and two examples of the head; and Dr. Dames points out that some of the scales have been named G. maximus, Ag., and G. tennistriatus, Ag. G. Quenstedti is a new species, founded upon the hinder portion of a fish, remarkable for the great length of the anal fin and the comparatively remote situation of the dorsal. The genus Colobodus proves to be a Lepidosteoid Ganoid related to Lepidotus, and having no connection with the Pycnodonts, to which it is commonly assigned. It differs from Lepidotus, so far as known, in the presence of an apical tubercle upon the rounded teeth, in the prominence of the scale-ornament, and in the depressed form of the head. Considerable variation, however, is exhibited in the five recognized species; and while relegating Ductylolepis, Nephrotus, ani Asterodon to the synonymy, Dr. Dames suspects that future discoveries may possibly justify the retention of the two first-mentioned names for the peculiar species to which they were originally applied. The fins and the precise form of the trunk are still unknown in all the species: but tolerably complete specimens of the squamation and dentition are described, and these lead to a considerable reduction in the number of “species” based upon isolated scales and teeth. A new genus and species, Crenilepis Sandbergeri, is founded upon a well-preserved portion of the squamation of a large fish from the Upper Muschelkalk of Krainberg, evidently related to the earlier Lepidosteoids, and distinguished by the form and ornamen- tation of the scales. In the anterior part of the flank, the scales are very much deeper than broad; and those of all parts are externally sculptured with a number of delicate branching furrows. The type- “species of the genus Serrolepis, Quenstedt, from the Lettenkohle, is now named S. suevicus; but only scattered scales are known, and Dames doubtfully associates with this fish a frag- ment of jaw, with stout styliform teeth, discovered upon the same slab of stone. On the whole, the genus seems most probably allied to Dapedius. In conclusion, Dr. Dames discusses an interesting problematical fish from the Upper Muschelkalk of Brunswick, not yet determinable, but in some respects suggestive of close relationship with the Semionotide. A summary of results then follows, and it is in- teresting to note how the distribution of species of Ganoids in the Muschelkalk agrees well with that of the Crinoids and the Cephalo- pods, the Lower, Middle, and Upper divisions being distinctly separated, and also the overlying Lettenkohle. A brief appendix records the occurrence of other well-preserved Ganoids in the same formation, including probably a new Paleoniscid genus, a new species of Gyrolepie, and a fish allied to Pholidophorus. These, and any other materials with which the author may be favoured, will form the subject of a second memoir to which we look forward with considerable interest. AS We _ “4 me ey try. Reports and Proceedings—British Association. 461 REPORTS AND PROCHHDINGS. perse. beth i Firty-ninta Annuat Meetine oF THE British ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. NeEwcastLE-upon-Tynz, 1889. ADDRESS TO THE GEOLOGICAL SECTION OF THE British Assocra- T10oN. By Professor James Gurxis, LL.D., F.R.SS. L. & E., F.G.S., President of the Section, September 12th, 1889. FTER some introductory remarks, Prof. James Geikie said: Perhaps there is no department of geological inquiry that has given rise to more controversy than that of Glacial Geology, which I have selected for the subject of this address. Hardly a single step in advance has been taken without veliement opposition. But the din of contending sides is not so loud now—the dust of the conflict has to some extent cleared away, and the positions which have been lost or maintained, as the case may be, can be readily discerned. The glacialist who can look back over the last twenty-five years of wordy conflict has every reason to be jubilant and hopeful. Many of those who formerly opposed him have come over to his side. It is true he has not had everything his own way. Some extreme views have been abandoned in the struggle; that of a great polar ice-sheet, for example, as conceived by Agassiz. I am not aware, however, that many serious students of Glacial Geology ever adopted that view. But it was quite an excusable hypothesis, and has been abundantly suggestive. Had Agassiz lived to see the detailed work of these later days, he would doubtless have modified his notion, and come to accept the view of large continental glaciers which has taken its place. The results obtained by geologists, who have been studying the peripheral areas of the drift-covered regions of our continent, are such as to satisfy us that the drifts of those regions are not iceberg- droppings, as we used to suppose, but true morainic matter and fluvio-glacial detritus. Geologists have not jumped to this conclu- sion—they have only accepted it after laborious investigation of — the evidence, Since Dr. Otto Torell, in 1875, first stated his belief that the “diluvium” of North Germany was of glacial origin a great literature on the subject has sprung up, a perusal of which will show that with our German friends Glacial Geology has passed through much the same succession of phases as with us. At first icebergs are appealed to as explaining everything—next we meet with sundry ingenious attempts at a compromise between floating- ice and a continuous ice-sheet. As observations multiply, however, the element of floating-ice is gradually eliminated, and all the phe- nomena are explained by means of land-ice and ‘‘schmelz-wasser ” alone. It is a remarkable fact that the iceberg hypothesis has always been most strenuously upheld by geologists whose labours have been largely confined to the peripheral areas of drift-covered countries. In the upland and mountainous tracts, on the other hand, 462 Reports and Proceedings—British Association— that hypothesis has never been able to survive a moderate amount of accurate observation. Hven in Switzerland—the land of glaciers —geologists at one time were of opinicen that the Boulder-clays of the low grounds had a different origin from those which occur in the mountain-valleys. Thus it was supposed that at the close of the Pleistocene period the Alps were surrounded by great lakes or gulfs of some inland sea, into which the glaciers of the high valleys flowed and calved their icebergs—these latter scattering erratics and earthy débris over the drowned areas. Sartorius von Waltershausen ! set forth this view in an elaborate and well-illustrated paper. Un- fortunately for his hypothesis, no trace of the supposed great lakes or inland sea has ever been detected—on the contrary, the character of the morainic accumulations, and the symmetrical grouping and radiation of the erratics and perched blocks over the tfoot-hills and low grounds, show that these last have been invaded and overflowed by the glaciers themselves. Even the most strenuous upholders of the efficacy of icebergs as originators of some Boulder-clays admit that the Boulder-clay or till, of what we may call the inner or central region of a glaciated tract, is the product of land-ice. Under this category comes the Boulder-clay of Norway, Sweden, and Finland, and of the Alpine lands of Central Europe, not to speak of the hilly parts of our own islands. When we come to study the drifts of the peripheral areas it is not difficult to see why these should be considered to have had a different origin. They present certain features which, although not absent from the glacial deposits of the inner region, are not nearly so characteristic of such upland tracts. I refer especially to the frequent interstratification of Boulder-clays with well-bedded deposits of clay, sand, and gravel; and to the fact that these Boulder-clays are often less compressed than those of the inner region, and have even occasionally a somewhat silt-like character. Such appearances do seem at first to be readily explained on the assumption that the deposits have been accumulated in water opposite the margin of a continental glacier or ice-sheet—and this was the view which several able investigators in Germany were for some time inclined to adopt. But when the phenomena came to be studied in greater detail, and over a wider area—this preliminary hypothesis did not prove satisfactory. It was discovered, for example, that ‘ giants’ kettles”? were more or less commonly distributed under the glacial deposits, and such “kettles” could only have originated at the bottom of a glacier. Again it was found that pre-Glacial accumulations were plentifully developed in certain places below the drift, and were often involved with the latter in a remarkable way. ‘The “ brown- coal-formation” in like manner was violently disturbed and displaced, to such a degree that frequently the Boulder-clay is found to underlie 1 Untersuchungen tiber die Klimate der Gegenwart und der Vorwelt, etc. Natuurkundige Verhandelingen vy. d. Holland, Maatsch. d. Wetensch. te Haarlem, 1866 2 These appear to have been first detected by Professor Berendt and Professor E. Geinitz. Prof. James Geikie’s Address. 463 it. Similar phenomena were encountered in regions where the drift underlies the Chalk—the latter presenting the appearance of having been smashed and shattered —the fragments having often been dragged some distance, so as to form a kind of friction-breccia under- lying the drift, while large masses are often included in the clay itself. All the facts pointed to the conclusion that these disturbances were due to tangential thrusting or crushing, and were not the result of vertical displacements, such as are produced by normal. faulting, for the disturbances in question die out from above downwards. Evidence of similar thrusting or crushing is seen in the remarkable faults and contortions that so often characterize the clays and sands that occur in the Boulder-clay itself. The only agent that could produce the appearances now briefly referred to is land-ice, and we must therefore agree with German geologists that glacier-ice has overflowed all the drift-covered regions of the peripheral area. No evidence of marine action in the formation of the stony clays is forthcoming—not a trace of any sea-beach has been detected. And yet, if these clays had been laid down in the sea during the retreat of the ice-sheet from Germany, surely such evidence as I have indicated ought to be met with. To the best of my knowledge the only particular facts which have been appealed to, as proofs of marine action, are the appearance of bedded deposits in the Boulder- clays, and the occasional occurrence in the clays themselves of a sea-shell. But other organic remains are also met with now and again in similar positions, such as mammalian bones and fresh-water shells. All these, however, have been shown to be derivative in their origin—they are just as much erratics as the stones and boulders with which they are associated. The only phenomena, therefore, that the glacialist has to account for are the bedded deposits which occur so frequently in the Boulder-clays of the peripheral regions, and the occasional silty and uncompressed character of the clays themselves. The intercalated beds are, after all, not hard to explain. If we consider for a moment the geographical distribution of the Boulder- clays, and their associated aqueous deposits, we shall find a clue to their origin. Speaking in general terms the stony clays thicken out as they are followed from the mountainous and high-lying tracts to the low ground. Thus they are of inconsiderable thickness in Norway, the higher parts of Sweden, and in Finland, just as we find is the case in Scotland, Northern England, Wales, and the hilly parts of Ireland. Traced south from the uplands of Scandinavia and Finland, they gradually thicken out as the low grounds are approached. Thus in Southern Sweden they reach a thickness of 48 metres or thereabout, and of 80 metres in the northern parts of Prussia, while over the wide low-lying regions to the south they attain a much greater thickness—reaching in Holstein, Mecklenburg, Pomerania, and West Prussia a depth of 120 to 140 metres, and still greater depths in Hanover, Mark Brandenburg, and Saxony. In those regions, however, a considerable portion of the ‘“ diluvium ” consists, as we Shall see presently, of water-formed beds. 464 Reports and Proceedings—British Association— The geographical distribution of the aqueous deposits which are associated with the stony clays is somewhat similar. They are very sparingly developed in districts where the Boulder-clays are thin. Thus they are either wanting, or only occur sporadically in thin irregular beds, in the high grounds of Northern Europe generally. Further south, however, they gradually acquire more importance until in the peripheral regions of the drift-covered tracts they come to equal and eventually to surpass the Boulder-clays in prominence. These latter, in fact, at last cease to appear, and the whole bulk of the “diluvium ” along the southern margin of the drift area appears to consist of aqueous accumulations alone. The explanations of these facts advanced by German geologists are quite in accordance with the views which have long been held by glacialists elsewhere, and have been tersely summed up by Dr. Jentzsch.' The northern regions, he says, were the feeding-grounds of the inland ice. In those regions melting was at a minimum, while the grinding action of the ice was most effective. Here, therefore, erosion reached its maximum—ground-moraine or Boulder-clay being unable to accumulate to any thickness. Further south melting greatly increased, while ground-moraine at the same time tended to accumulate—the conjoint action of glacier-ice and sub-Glacial water resulting in the complex drifts of the peripheral area. In the disposition and appearance of the aqueous deposits of the “ diluvium ” we have evidence of an extensive sub-Glacial water-circulation— glacier-mills that gave rise to ‘giants’ kettles’”’—chains of sub- glacial lakes in which fine clays gathered—streams and rivers that flowed in tunnels under the ice, and whose courses were paved with sand and gravel. Nowhere do German geologists find any evidence of marine action. On the contrary, the dove-tailing and interosculation of Boulder-clay with aqueous deposits are explained by the relation of the ice to the surface over which it flowed. Throughout the peripheral area it did not rest so continuously upon the ground as was the case in the inner region of maximum erosion. In many places it was tunnelled by rapid streams and rivers, and here and there it arched over sub-Glacial lakes, so that accumulation of ground- moraine proceeded side by side with the formation of aqueous sedi- ments. Much of that ground-moraine is of the usual tough and hard-pressed character, but here and there it is somewhat less coherent and even silt-like. Now a study of the ground-moraines of modern glaciers affords us a reasonable explanation of such differences. Dr. Briickner? has shown that in many places the ground-moraine of Alpine glaciers is included in the bottom of the ice itself. The ground-moraine, he says, frequently appears as an ice-stratum abundantly impregnated with silt and rock-fragments— it is like a conglomerate or breccia which has ice for its binding material. When this ground-moraine melts out of the ice—no running water being present—it forms a layer of unstratified silt or 1 Jahrb. d. kénigl. preuss. geologischen Landesanstalt fiir 1884, p. 438. 2 Die Vergletscherung des Salzachgebietes, etc.: Geographische Abhandlungen herausgegeben y. A. Penck, band i. hett 1. _ Prof. James Geikie’s Address. 465 clay, with stones scattered irregularly through it. Such being the ease in modern glaciers, we can hardly doubt that over the peripheral areas occupied by the old northern ice-sheet Boulder-clay must frequently have been accumulated in the same way. Nay, when the ground-moraine melted out and dropped here and there into quietly- flowing water, it might even acquire in part a bedded character. The limits reached by the inland ice during its greatest extensions are becoming more and more clearly defined, although its southern margin will probably never be so accurately determined as that of the latest epoch of general glaciation. The reasons for this are obvious. When the inland ice flowed south to the Harz and the hills of Saxony it formed no great terminal moraines. Doubtless many erratics and much rock-rubbish were showered upon the surface of the ice from the higher mountains of Scandinavia, but owing to fanning-out of the ice on its southward march such superficial debris was necessarily spread over a constantly widening area. It may well be doubted, therefore, whether it ever reached the terminal front of the ice-sheet in sufficient bulk to form conspicuous moraines. It seems most probable that the terminal moraines of the great inland ice would consist of low banks of Boulder-clay and aqueous materials —the latter, perhaps, strongly predominating, and containing here and there larger and smaller angular erratics which had travelled on the surface of the ice. However that may be, it is certain that the whole region in question has been considerably modified by sub- sequent denudation, and to a large extent is now concealed under deposits belonging to later stages of the Pleistocene period. The extreme limits reached by the ice are determined rather by the occasional presence of rock strie and roches moutonnées, of Boulder- clay and northern erratics, than by recognizable terminal moraines. The southern limits reached by the old inland ice appear in this way to have been tolerably well ascertained over a considerable portion of Central Europe. Some years ago I published a small sketch-map ! showing the extent of surface formerly covered by ice. On this map I did not venture to draw the southern margin of the ice-sheet in Belgium further south than Antwerp, where northern erratics were known to occur; but the more recent researches of Belgian geologists show that the ice probably flowed south for some little distance beyond Brussels.? Here and there in other parts of the Continent the southern limits reached by the northern drift have also been more accurately determined, but so far as I know, none of these later observations involves any serious modifications of the sketch-map referred to. I have now said enough, however, to show that the notion of a general ice-sheet having covered so large a part of Europe, which a few years ago was looked upon as a wild dream, has been amply justified by the labours of those who are so assiduously investigating the peripheral areas of the ‘‘ great northern drift.” And perhaps I may be allowed to express my own belief that the drifts of Middle and 1 Prehistoric Europe, 1881. 2 See a paper by M. E. Delvaux, Ann. de la Soc. géol. de Belg. t. xiii. p. 158. DECADE I1I.—VOL. VI.—NO. X. 30 466 Reports and Proceedings—British Association— Southern England, which exhibit the same complexity as the “ lower diluvium ” of the Continent, will eventually be generally acknow- ledged to have had a similar origin. I have often thought that whilst politically we are happy in having the sea all round us, geologically we should have gained perhaps by its greater distance. At all events we should have been less ready to invoke its assistance to explain every puzzling appearance presented by our glacial accumulations. J now pass on to review some of the general results obtained by continental geologists as to the extent of area occupied by inland ice during the last great extension of glacier-ice in Europe. It is well known that this latest ice-sheet did not overflow nearly so wide a region as that underneath which the lowest Boulder-clay was accumulated. This is shown not only by the geographical dis- tribution of the youngest Boulder-clay, but by the direction of rock-striz, the trend of erratics, and the position of well-marked moraines. Gerard de Geer has given a summary! of the general results obtained by himself and his fellow-workers in Sweden and Norway; and these have been supplemented by the labours of Berendt, Geinitz, Hunchecorne, Keilhack, Klockmann, Schréder, Wahnschaffe, and others in Germany, and by Sederholm in Finland.? From them we learn that the end-moraines of the ice circle round the southern coasts of Norway. from whence they sweep south-east by east across the province of Gottland in Sweden, passing through the lower ends of Lakes Wener and Wetter, while similar moraines mark out for us the terminal front of the inland ice in Finland—at least two parallel frontal moraines passing inland from Hango Head on the Gulf of Finland through the southern part of that province to the north of Lake Ladoga. Further north-east than this they have not been traced; but, from some observations by Helmersen, Sederholm thinks it probable that the terminal ice-front extended north-east by the north of Lake Onega to the eastern shores of the White Sea. Between Sweden and Finland lies the basin of the Baltic, which at the period in question was, filled with ice, forming a great Baltic glacier, which overflowed the Aland Islands, Gottland, and Oland, and which, fanning out as it passed towards the south- west, invaded, on the south side, the Baltic provinces of Germany, while, on the north, it crossed the southern part of Scania in Sweden and the Danish islands to enter upon Jutland. The Upper Boulder-clay of those regions is now recognized as the ground-moraine of this latest ice-sheet. In many places it is separated from the older Boulder-clay by inter-Glacial deposits, some of which are marine, while others are of fresh-water and terrestrial origin. During inter-Glacial times the sea that overflowed a considerable portion of North Germany was evidently continuous 1 Zeitschrift d. deutsch. geolog. Ges. Bd. xxvii. p. 177. ® For papers by Berendt and his associates see especially the Jahrbuch d. k. preuss. geol. Landesanstalt, and the Zeitschr. d. deutsch. geol. Ges. for the past few years. Geinitz, Forsch. z. d. Landes- u. Volkskunde, i. 5; Leopoldina, xxii. p. 37 ; I. Beitrag z. Geologie Mecklenburgs, 1880, p. 46,56; Sederholm, Fennia, i. No. 7. eee Prof. James Geikie’s Address. 467 with the North Sea, as is shown not only by the geographical dis- tribution of the inter-Glacial marine deposits, but by their North Sea fauna. German geologists generally group all the inter-Glacial deposits together, as if they belonged to one and the same inter- Glacial epoch. This perhaps we must look upon as only a provisional arrangement. Certain it is that the fresh-water and terrestrial beds which frequently occur on the same or a lower level and at no great distance from the marine deposits, cannot in all cases be contem- poraneous with the latter. Possibly, however, such discordances inay be accounted for by oscillations in the level of the inter-Glacial sea—land and water having alternately prevailed over the same area. ‘T'wo Boulder-clays, as we have seen, have been recognized over a wide region in North Germany. In some places, however, three or more such Boulder-clays have been observed overlying one another throughout considerable areas, and these clays are described as being distinctly separate and distinguishable the one from the other.!. Whether they with their intercalated aqueous deposits indicate great oscillations of one and the same ice-sheet—now advancing, now retreating—or whether the stony clays may not be the ground- moraines of so many different ice-sheets, separated the one from the other by true inter-Glacial conditions, future investigations must be left to decide. The general conclusions arrived at by those who are at present investigating the glacial accumulations of Northern Europe may be summarized as follows : 1. Before the invasion of Northern Germany by the inland ice the low grounds bordering on the Baltic were overflowed by a sea which contained a boreal and arctic fauna. These marine conditions are indicated by the presence under the Lower Boulder-clay of more or less well-bedded fossiliferous deposits. On the same horizon occur also beds of sand, containing fresh-water shells, and now and again mammalian remains, some of which imply cold and others temperate climatic conditions. Obviously all these deposits may pertain to one and the same period, or more properly to different stages of the same period--some dating back to a time when the climate was still temperate, while others clearly indicate the prevalence of cold conditions, and are therefore probably somewhat younger. 2. The next geological horizon in ascending order is that which is marked by the ‘ Lower Diluvium ”—the Glacial and fluvio-Glacial detritus of the great ice-sheet which flowed south to the foot of the © Harz Mountains. The Boulder-clay on this horizon now and again contains marine, fresh-water, and terrestrial organic remains, derived undoubtedly from the so-called pre-Glacial beds already referred to. These latter, it would appear, were ploughed up and largely incor- porated with the ground-moraine. 3. The inter-Glacial beds which next succeed contain remains of a well-marked temperate fauna and flora, which point to something more than a mere partial or local retreat of the inland ice. ‘he geographical distribution of the beds and the presence in these of 1 HH. Schréder, Jahrb. d. k. preuss. geol. Landesanstalt fur 1887, p. 360. 468 Reports and Proceedings— British Association— such forms as Elephas antiquus, Cervus elephas, C. megaceros, and a flora comparable to that now existing in Northern Germany, justify geologists in concluding that the inter-Glacial epoch was one of long duration, and characterized in Germany by climatic conditions ap- parently not less temperate than those that now obtain. One of the phases of that inter-Glacial epoch, as we have seen, was the over- flowing of the Baltic provinces by the waters of the North Sea. 4. To this well-marked inter-Glacial epoch succeeded another epoch of aretic conditions, when the Scandinavian inland ice once more invaded Germany, ploughing through the inter-Glacial deposits, and working these up in its ground-moraine. So far as I can learn, the prevalent belief among geologists in North Germany is that there was only one inter-Glacial epoch ; but, as already stated, doubt has been expressed whether all the facts can be thus accounted for. There must always be great difficulty in the correlation of widely- separated inter-Glacial deposits, and the time does not seem to me to have yet come when we can definitely assert that all those inter- Glacial beds belong to one and the same geological horizon. I have dwelt upon the recent work of geologists in the peripheral areas of the drift-covered regions of Northern Hurope, because I think the results obtained are of great interest to glacialists in this country. And for the same reason I wish next to call attention to what has been done of late years in elucidating the Glacial Geology of the Alpine lands of Central Europe—and more particularly of the low grounds that stretch out from the foot of the mountains. Any observations that tend to throw light upon the history of the com- plex drifts of our own peripheral areas cannot but be of service. It is quite impossible to do justice in this brief sketch to the labours of the many enthusiastic geologists who within recent years have increased our knowledge of the glaciation of the Alpine lands. At present, however, Iam not so much concerned with the proofs of - general glaciation as with the evidence that goes to show how the Alpine ground-moraines have been formed, and with the facts which have led certain observers to conclude that the Alps have endured several distinct glaciations within Pleistocene times. Swiss geolo- gists are agreed that the ground-moraines which clothe the bottoms of the great Alpine valleys, and extend outwards sometimes for many miles upon the low grounds beyond are of true glacial origin. Now these ground-moraines are closely similar to the Boulder-clays of this country and Northern Europe. Like them, they are frequently tough and hard-pressed, but now and again somewhat looser and less firmly coherent. Frequently also they contain lenticular beds, and more or less thick sheets of aqueous deposits—in some places the stony clays even exhibiting a kind of stratification—and ever and anon such water-assorted materials are commingled with stony clay in the most complex manner. These latter appearances are, how- ever, upon the whole best developed upon the low grounds that sweep out from the base of the Alps. The only question concerning the ground-moraines that has recently given rise to much discussion is the origin of the materials themselves. It is obvious that there Prof. James Geikie’s Address. 469 are only three possible modes in which those materials could have _ been introduced into the ground-moraine : either they consist of super- ficial morainic débris which has found its way down to the bottom of the old glaciers by crevasses; or they may be made up of the rock-rubbish, shingle, gravel, etc., which doubtless strewed the — valleys before these were occupied by ice; or, lastly, they may have been derived in chief measure from the underlying rocks themselves by the action of the ice that overflowed them. The investigations of Penck, Blaas, Bohm, and Briickner appear to me to have demon- strated that the ground-moraines are composed mostly of materials which have been detached from the underlying rocks by the erosive action of the glaciers themselves. Their observations show that the regions studied by them in great detail were almost completely buried under ice, so that the accumulation of superficial moraines was for the most part impossible; and they advance a number of facts which prove positively that the ground-moraines were formed and accumulated under ice. I cannot here recapitulate the evidence, but must content myself by a reference to the papers in which this is fully discussed. These geologists do not deny that some of the material may occasionally have come from above, nor do they doubt that pre-existing masses of rock-rubbish and alluvial accumulations may have been incorporated with the ground-moraines; but the enormous extent of the latter, and the direction of transport and distribution of the erratics which they contain cannot be thus ac- counted for, while all the facts are readily explained by the action of the ice itself, which used its sub-Glacial débris as tools with which to carry on the work of erosion. Professor Heim and others have frequently asserted that glaciers have little or no eroding power, since at the lower ends of existing glaciers we find no evidence of such erosion being in operation. But the chief work of a glacier cannot be carried on at its lower end, where motion is reduced to a minimum, and where the ice is per- forated by sub-Glacial tunnels and arches, underneath which no glacial erosion can possibly take place; and yet it is upon observa- tions made in just such places that the principal arguments against the erosive action of glaciers have been based. If all that we could ever know of glacial action were confined to what we can learn from peering into the grottoes at the terminal fronts of existing glaciers we should indeed come to the conclusion that glaciers do not erode their rocky beds to any appreciable extent. But as we do not look for the strongest evidence of fluviatile erosion at the mouth of a river, but in its valley- and mountain-tracks, so if we wish to learn what glacier-ice can accomplish, we must study in detail some wide region from which the ice has completely disappeared. When this plan has been followed, it has happened that some of the strongest opponents of glacial erosion have been compelled by the force of the evidence to go over to the other camp. Dr. Blaas, for 1 Penck: Die Vergletscherung der deutschen Alpen. Blaas: Zeitsch. d. Fer- dinandeums, 1885. Bohm: Jahrb. d. k. k. geol. Reichsanstalt, 1885. bd. xxxv. Heft 3. Briickner: Die Vergletscherung d. Salzachgebietes, etc., 1886. * 470 Reports and Proceedings—Biitish Association— example, has been led by his observations on the glacial formations of the Inn Valley to recant his former views, and to become a formidable advocate of the very theory which he formerly opposed. To his work and the memoirs by Penck, Briickner, and Bohm already cited, and especially to the admirable chapter on glacier- erosion by the last-named author, I would refer those who may be anxious to know the last word on this much-debated question. The evidence of inter-Glacial conditions within the Alpine lands continues to increase. These are represented by alluvial deposits of silt, sand, gravel, conglomerate, breccia, and lignites. Penck, Bohm, and Brickner find evidence of two inter-Glacial epochs, and maintain that there have been three distinct and separate epochs of glaciation in the Alps. No mere temporary retreat and re-advance of the glaciers, according to them, will account for the phenomena presented by the inter-Glacial deposits and associated morainic accu- mulations. During inter-Glacial times the glaciers disappeared from the lower valleys of the Alps—the climate was temperate, and probably the snow-fields and glaciers approximated in extent to those of the present day. All the evidence conspires to show that an inter-Glacial epoch was of prolonged duration. Dr. Briickner has observed that the moraines of the last. Glacial epoch rest here and there upon léss, and he confirms Penck’s observations in South Bavaria that this remarkable formation never overlies the morainic accumulations of the latest Glacial epoch. According to Penck and Brickner, therefore, the léss is of inter-Glacial age. There can be little doubt, however, that léss does not belong to any one particular horizon. Wahnschaffe! and others have shown that throughout wide areas in North Germany it is the equivalent in age of the ‘Upper Diluvium,’ while Schumacher ® points out that in the Rhine valley it occurs on two separate and distinct horizons. Prof. Andrez has likewise shown ° that there is an upper and lower loss in Alsace, each characterized by its own special fauna. There is still considerable difference of opinion as to the mode of formation of this remarkable accumulation. By many it is considered to be an aqueous deposit ; others, following Richthofen, are of opinion that it is a wind-blown accumulation; while some incline to the belief that it is partly one and partly the other. Nor do the upholders of these various hypotheses agree amongst themselves as to the precise manner in which water or wind has worked to produce the observed results. Thus, amongst the supporters of the aqueous origin of the léss, we find this attributed to the action of heavy rains washing over and rearranging the material of the Boulder-clays.* Many, again, have held it probable that loss is simply the finest loam distributed over the low grounds by the flood-waters that escaped 1 Abhandl. z. geol. Specialkarte v. Preussen, etc., bd. vii. heft 1 ; Zeitschr. d. deutsch, geol. Gesellsch., 1885, p. 204; 18%6, p. 367. 2 Hygienische Topographie von Strassburg i. F., 1885. 3 Abhandl. z. geol. Specialkarte v. Elsass-Lothringen, bd. vii., heft 2. 4 Laspeyres : Erlauterungen z. geol. Specialkarte y. Preussen, etc., Blatt Grobzig, Zorbig, und, Petersberg. Prof. James Geikie’s Address. , 471. from the northern inland ice and the mers de glace of the Alpine lands of Central Hurope. Another suggestion is that much of the material of the loss may have been derived from the denudation of the Boulder-clays by flood-water, during the closing stages of the last cold period. It is pointed out that in some regions at least the léss is underlaid by a layer of erratics, which are believed to be the residue of the denuded Boulder-clay. We are reminded by Klockmann! and Wahnschaffe*® that the inland ice must have acted as a great dam, and that wide areas in Germany, etc., would be flooded, partly by water derived from the melting inland ice, and partly by waters flowing north from the hilly tracts of Middle Germany. In the great basins thus formed there would be a com- mingling of fine silt-material derived from north and south, which _ would necessarily come to form a deposit having much the same character throughout. From what I have myself seen of the léss in various parts of Germany, and from all that I have gathered from reading and in conversation with those who have worked over ldss-covered regions, I incline to the opinion that loss is for the most part of aqueous origin. In many cases this can be demonstrated, as by the occurrence of bedding and the intercalation of layers of stones, sand, gravel, ete., in the deposit; again, by the not infrequent appearance of fresh- water shells; but, perhaps, chiefly by the remarkable uniformity of character which the léss itself displays. It seems to me reasonable also to believe that the flood-waters of Glacial times must needs have been highly charged with finely-divided sediment, and that such sediment would be spread over wide regions in the low grounds— in the slack-waters of the great rivers and in the innumerable temporary lakes which occupied, or partly occupied, many of the valleys and depressions of the land. There are different kinds of loss or léss-like deposits, however, and all need not have been formed in the same way. Probably some may have been derived, as Wahn- schaffe has suggested, from the denudation of Boulder-clay. Possibly, also, some léss may owe its origin to the action of rain upon the stony clays, producing what we in this country would call “ rain- wash.” There are other accumulations, however, which no aqueous theory will satisfactorily explain. Under this category comes much of the so-called Bergléss, with its. abundant land-shells, and its generally unstratified character. It seems likely that such loss is simply the result of subaerial action, and owes its origin to rain, frost, and wind acting upon the superficial formations, and rearranging their finer-grained constituents. And it is quite possible that the upper portion of much of the loss of the lower grounds may have been reworked in the same way. But I confess I cannot yet find in the facts adduced by German geologists any evidence of a dry-as- dust epoch having obtained in Hurope during any stage of the Pleistocene period. The geographical position of our continent seems to me to forbid the possibility of such climatic conditions, 1 Klockmann: Jahrb. d. k. preuss, geol. Landesanstalt fiir 1883, p. 262. * Wahnschaffe : up. cit. and Zeitschr. d, deutsch, geol. Ges, 1886, p. 367. 472 Reports and Proceedings—British Association— while all the positive evidence we have points rather to humidity than dryness as the prevalent feature of Pleistocene climates. It is obvious, however, that after the flood-waters had disappeared from the low grounds of the Continent, subaerial action would come into play over the wide regions covered by Glacial and fluvio-Glacial deposits. Thus, in the course of time, these deposits would become modified,—just as similar accumulations in these islands have been top-dressed, as it were, and to some extent even rearranged. I am strengthened in these views by the conclusions arrived at by M. Falsan, the eminent French glacialist. Covering the plateaux of the Doubs, and widely spread throughout the valleys of the Rhone, the Ain, the Isére, etc., in France, there is a deposit of léss, he says, which has been derived from the washing of the ancient moraines. At the foot of the Alps, where black schists are largely developed, the loss is dark grey; but west of the secondary chain the same deposit is yellowish, and composed almost entirely of siliceous materials, with only a very little carbonate of lime. This /imon or loss, however, is very generally modified towards the top by the chemical action of rain, the yellow léss acquiring a red colour. Sometimes it is crowded with calcareous concretions; at other times it has been deprived of its calcareous element and converted into a kind of pulverulent silica or quartz. This, the true léss, is distin- guished from another lehm, which Falsan recognizes as the product of atmospheric action—formed, in fact, in place from the disintegration and decomposition of the subjacent rocks. Even this lehm has been modified by running water—dispersed or accumulated locally, as the case may be.! All that we know of the loss and its fossils compels us to include this accumulation as a product of the Pleistocene period. It is not of post-Glacial age—even much of what one may call the ‘“‘ remodified loss” being of Late Glacial or Pleistocene age. I cannot attempt to give here a summary of what has been learned within recent years as to the fauna of the loss. The researches of Nehring and Liebe have familiarized us with the fact that at some particular stage in the Pleistocene period a fauna like that of the alpine steppe-lands of Western Asia was indigenous to Middle Europe, and the recent investigations of Woldrich have increased our knowledge of this fauna. At what horizon, then, does this steppe-fauna make its appearance ? At Thiede Dr. Nehring discovered in so-called léss three successive horizons, each characterized by a special fauna. ‘The lowest of these faunas was decidedly Arctic in type; above that came a steppe-fauna, which last was succeeded by a fauna comprising such forms as Mammoth, woolly Rhinoceros, Bos, Cervus, Horse, Hyena, and Lion. Now, if we compare this last fauna with the forms which have been obtained from true post-Glacial deposits— those deposits, namely, which overlie the younger Boulder-clays and flood-accumulations of the latest Glacial epoch, we find little in common. The Lion, the Mammoth, and the Rhinoceros are con- spicuous by their absence from the post-Glacial beds of Hurope. 1 Falsan : La Période glaciaire, p. 81. Prof. James Geikie’s Address. 473 In place of them we meet with a more or less Arctic fauna, and a high-Alpine and Arctic flora, which, as we all know, eventually gave place to the flora and fauna with which Neolithic man was contempo- raneous. ‘As this is the case throughout North-Western and Central Europe, we seem justified in assigning the Thiede beds to the Pleistocene period, and to that inter-Glacial stage which preceded and gradually merged into the last Glacial epoch. That the steppe- fauna indicates relatively drier conditions of climate than obtained when perennial snow and ice covered wide areas of the low ground goes without saying; but I am unable to agree with those who maintain that it implies a dry-as-dust climate, like that of some of the steppe-regions of our own day. The remarkable commingling of Arctic and steppe-faunas discovered by Woldrich in the Bohmer- - wald! shows, I think, that the Jerboas, Marmots, and Hamster-rats were not incapable of living in the same regions contemporaneously with Lemmings, Arctic Hares, Siberian Social Voles, ete. But when a cold epoch was passing away the steppe-forms probably gradually replaced their Arctic congeners, as these migrated northwards during the continuous amelioration of the climate. If the student of the Pleistocene faunas has certain advantages in the fact that he has to deal with forms many of which are still living, he labours at the same time under disadvantages which are unknown to his colleagues who are engaged in the study of the life of far older periods. The Pleistocene period was distinguished above all things by its great oscillations of climate—the successive changes being repeated, and producing correlative migrations of floras and faunas. We know that Arctic and temperate faunas and floras flourished during inter-Glacial times, and a like succession of life- forms followed the final disappearance of Glacial conditions. A study of the organic remains met with in any particular deposit will not necessarily, therefore, enable us to assign these to their proper horizon. The geographical position of the deposit, and its relation — to Pleistocene accumulations elsewhere, must clearly be taken into account. Already, however, much has been done in this direction, and it is probable that ere long we shall be able to arrive at a fair knowledge of the various modifications which the Pleistocene floras and faunas experienced during that protracted period of climatic changes of which I have been speaking. We shall even possibly learn how often the Arctic, steppe-, prairie-, and forest-faunas, as they have been defined by Woldrich, replaced each other. Even now some approximation to this better knowledge has been made. Dr. Pohlig,” for example, has compared the remains of the Pleistucene faunas obtained at many different places in Europe, and has presented. us with a classification which, although confessedly incomplete, yet 1 Woldrich : Sitzungsb. d. kais. Akad. d. W. math. nat. Cl., 1880, p. 7; 1881, p- 177; 1883, p. 978. 2 Pohlig: Sitzungsb. d, Niederrheinischen Gesellschaft zu Bonn, 1884; Zeitschr. d. deutsch. geolog. Ges., 1887, p. 798. For a very full account of the diluvial European and Northern Asiatic mammalian faunas by Woldrich, see Mém. de l’Acad. des sciences de St. Pétersbourg, viie. sér, t. xxxv. 1887. 474 Reports and Proceedings—British Association— serves to show the direction in which we must look for further advances in this department of inquiry. During the last twenty years the evidence of inter-Glacial conditions both in EHurope and America has so increased that geologists generally no longer doubt that the Pleistocene period was characterized by great changes of climate. The occurrence at many different localities on the Continent of beds of lignite and fresh-water alluvia, contain- ing remains of Pleistocene mammalia, intercalated between separate and distinct Boulder-clays, has left us no alternative. The inter- Glacial beds of the Alpine lands of Central Europe are paralleled by similar deposits in Britain, Scandinavia, Germany, and France. But opinions differ as to the number of Glacial and inter-Glacial epochs —many holding that we have evidence of only two cold stages and one general inter-Glacial stage. This, as I have said, is the view entertained by most geologists who are at work on the Glacial accumulations of Scandinavia and North Germany. On the other hand, Dr. Penck and others, from a study of the drifts of the German Alpine lands, believe that they have met with evidence of three dis- tinct epochs of glaciation, and two epochs of inter-Glacial conditions. In France, while some observers are of opinion that there have been only two epochs of general glaciation, others, as, for example, M. Tardy, find what they consider to be evidence of several such epochs. Others again, as M. Falsan, do not believe in the existence of any inter-Glacial stages, although they readily admit that there were great advances and retreats of the ice during the Glacial period. M. Falsan, in short, believes in oscillations, but is of opinion that these were not so extensive as others have maintained. It is, therefore, simply a question of degree, and whether we speak of oscillations or of epochs, we must needs admit the fact that throughout all the glaciated tracts of Kurope, fossiliferous deposits occur intercalated among glacial accumulations. ‘The successive advance and retreat of the ice, therefore, was not a local phenomenon, but characterized all the glaciated areas. And the evidence shows that the oscillations referred to were on a gigantic scale. The relation borne to the glacial accumulations by the old river alluvia which contains relics of Paleolithic man early attracted attention. From the fact that these alluvia in some places overlie glacial deposits, the general opinion (still held by some) was that Paleolithic man must needs be of post-Glacial age. But since we have learned that all Boulder-clay does not belong to one and the same geological horizon—that, in short, there have been at least two, and probably more, epochs of glaciation—it is obvious that the mere occurrence of glacial deposits under Paleolithic gravels does not ‘prove these latter to be post-Glacial. All that we are entitled in such a case to say is simply that the implement-bearing beds are younger than the glacial accumulations upon which they rest. Their horizon must be determined by first ascertaining the relative position in the Glacial series of the underlying deposits. Now, it is a remarkable fact that the Boulder-clays which underlie such old alluvia belong, without exception, to the earlier stages of the Glacial Prof. James Geikie’s Address. — ATS period. This has been proved again and again, not only for this country but for Hurope generally. I am sorry to reflect that some twenty years have now elapsed since I was led to suspect that the Paleolithic gravels and cave-deposits were not of post-Glacial, but of Glacial and inter-Glacial age. In 1871-72 I published a series of papers in the Geotoercan Magazine in which I set forth the views I had come to form upon this interesting question. In these papers it was maintained that the alluvia and cave deposits could not be of post-Glacial age, but must be assigned to pre-Glacial and inter- Glacial times, and in chief measure to the latter. Evidence was led to show that the latest great development of glacier-ice in Hurope took place after the southern Pachyderms and Paleolithic man had vacated England—that during this last stage of the Glacial period man lived contemporaneously with a northern and Alpine fauna in such regions as Southern France—and lastly, that Paleolithic man and the Southern Mammalia never revisited North-Western Hurope after extreme glacial conditions had disappeared. These conclusions were arrived at after a somewhat detailed examination of all the evidence then available—the remarkable distribution of the Paleo- lithic and ossiferous alluvia having, as I have said, particularly impressed me. I coloured a map to show at once the areas covered by the glacial and fluvio-Glacial deposits of the last Glacial epoch, and the regions in which the implement-bearing and ossiferous alluvia had been met with, when it became apparent that the latter never occurred at the surface within the regions occupied by the former. It ossiferous alluvia did here and there appear within the recently glaciated areas it was always either in caves, or as infra- or inter-Glacial deposits. Since the date of these researches our knowledge of the geographical distribution of Pleistocene deposits has greatly increased, and implements and other relics of Palzolithic man have been recorded from many new localities throughout Europe. But none of this fresh evidence contradicts the conclusions I had previously arrived at; on the contrary, it has greatly strength- ened my general argument. Professor Penck was, I think, the first on the Continent to adopt the views referred to. He was among the earliest to recognize the evidence of inter-Glacial conditions in the drift-covered regions of Northern Germany, and it was the reflections which those remark- able inter-Glacial beds were so well calculated to suggest that led him into the same path as myself. Dr. Penck has published a map * showing the areas covered by the earlier and later glacial deposits in Northern Europe and the Alpine lands, and indicating at the same time the various localities where Paleolithic finds have occurred. And in not a single case do any of the latter appear within the areas covered by the accumulations of the last Glacial epoch. A glance at the papers which have been published in Germany within the last few years will show how greatly students of the Pleistocene ossiferous beds have been influenced by what is now known of the inter-Glacial deposits and their organic remains. 1 Archiv fiir Anthropologie, bd, xv. heft 3, 1884. 476 Reports and Proceedings—British Association— Professors Rothpletz! and Andree,? Dr. Pohlig® and others, do not now hesitate to correlate with those beds the old ossiferous and implement-bearing alluvia which lie altogether outside of glaciated regions. The relation of the Pleistocene alluvia of France to the glacial deposits of that and other countries has been especially canvassed. Roihpletz, in the paper cited below, includes these alluvia amongst the inter-Glacial deposits; and in the present year we have an interesting essay on the same subject by the accomplished secretary of the Anthropological and Archeological Congress, which met last month in Paris. M. Boule correlates* the Paleolithic eave- and river-deposits of France with those of other countries, and shows that they must be of inter-Glacial age. His classification, I am gratified to find, does not materially differ from that given by myself a number of years ago. He is satisfied that in France there is evidence of three Glacial epochs and two well-marked inter- Glacial horizons. The oldest of the Paleolithic stages of Mortillet (CHELLEENNE) culminated according to Boule during the last inter- Glacial epoch, while the more recent Paleolithic stages (MousrErt- ENNE, SOLUTREENNE, and MagpaLénieNNE) coincided with the last great development of glacier-ice. ‘The Paleolithic age, so far as Europe is concerned, came to a close during this last cold phase of the Glacial period. There are many other points relating to Glacial Geology which have of late years been canvassed by continental workers, but these I cannot discuss here. I have purposely, indeed, restricted my remarks to such parts of a wide subject as I thought might have interest for glacialists in this country, some of whom may not have had their attention directed to the results which have recently been attained by their fellow-labourers in other lands. Had time permitted I should gladly have dwelt upon the noteworthy advances made by our American brethren in the same department of inquiry. Especially should I have wished to direct attention to the remarkable evidence adduced in favour of the periodicity of glacial action. Thus Messrs. Chamberlin and Salisbury, after a general review of that evidence, maintain that the Ice Age was interrupted by one chief inter-Glacial epoch, and by three inter-Glacial sub-epochs or episodes of deglaciation. The same authors discuss at some length the origin of the loss, and come to the general conclusion that while deposits of this character may have been formed at different stages of the Glacial period, and under different conditions, yet that upon the whole they are best explained by aqueous action. Indeed a perusal of the recent geo- logical literature of America shows a elose accord between the theoretical opinions of many transatlantic and European geologists. Thus as years advance the picture of Pleistocene times becomes ' Rothpletz : Denkschrift d. schweizer. Ges. fiir d. gesammt. Nat., bd. xxviii. 1881. * Andrew ; Abhandl. z. geolog. Specialkarte v. Elsass-Lothringen, bd. iv. heft 2, 1884. 3 Pohlig : op. cit. 4 Boule: Revue d’ Anthropologie, 1889, t. i. Prof. James Geikie’s Adilress. — 477 more and more clearly developed. The conditions under which our old Paleolithic predecessors lived—the climatic and geographical changes of which they were the witnesses—are gradually being re- vealed with a precision that only a few years ago might well have seemed impossible. This of itself is extremely interesting, but I feel sure that I speak the conviction of many workers in this field of labour when I say that the clearing up of the history of Pleistocene times is not the only end which they have in view. One can hardly doubt that when the conditions of that period and the causes which gave rise to these have been more fully and definitely ascertained, we shall have advanced some way towards the better understanding of the climatic conditions of still earlier periods. For it cannot be denied that our knowledge of Paleozoic, Mesozoic, and even early _ Cainozoic climates is unsatisfactory. But we may look forward to the time when much of this uncertainty will disappear. Meteoro- logists are every day acquiring a clearer conception of the distribution of atmospheric pressure and temperature, and the causes by which that distribution is determined, and the day is coming when we shall be better able than we are now to apply this extended meteorological knowledge to the explanation of the climates of former periods in the world’s history. One of the chief factors in the present dis. tribution of atmospheric temperature and pressure is doubtless the relative position of the great land and water areas; and if this be true of the present, it must be true also of the past. It would almost seem then as if all one had to do to ascertain the climatic condition of any particular period was to prepare a map, depicting with some approach to accuracy the former relative position of land and sea. With such a map could our meteorologists infer what the climatic conditions must have been? Yes, provided we could assure them that in other respects the physical conditions did not differ from the present. Now there is no period in the past history of our globe the geographical conditions of which are better known than the Pleistocene. And yet, when we have indicated these upon a map, we find that they do not give the results which we might have expected. The climatic conditions which they seem to imply are not such as we know did actually obtain. It is obvious, therefore, that some additional and perhaps exceptional factor was at work to produce the recognized results. What was this disturbing element, and have we any evidence of its interference with the operation of the normal agents of climatic change in earlier periods of the world’s history? We all know that various answers have been given to such questions. Whether amongst these the correct solution of the enigma is to be found time will show. Meanwhile, as all hypothesis and theory must starve without facts to feed on, it behoves us as working geologists to do our best to add to the supply. The success with which other problems have been attacked by geologists forbids us to doubt that ere long we shall have done much to dispel some of the mystery which still envelopes the question of geological climates. 478 Reports and Proceedings— British Association— BririsH ASSocriaATION FOR THE ADVANCEMENT OF SCIENCE. SEPTEMBER 127H to 187TH, 1889. List of Titles of Papers read in Section (C) Geology. Professor James Guixize, D.C.L., LL.D., F.R.S., F.G.S., President. The President’s Address. (See page 461.) Prof. J. Milne.—Report on the Earthquake and Volcanic Phenomena of Japan. Prof. G. Michie Smith—The Bandaisan Eruption, Japan, July, 1888. Dr. E. Naumann.—Terrestrial Magnetism as modified by the Struc- ture of the Harth’s Crust; and Proposals concerning a Magnetic Survey of the Globe. T. P. Barkas.—Notes on numerous newly discovered Fossil Foot- prints on the Lower Carboniferous Sandstone of Northumberland, near Otterburn. T. Mellard Reade.—The Physiography of the Lower Trias. Dr. A. Geikie.—Origin and Age of the Crystalline Schists of Norway. J. H. Marr.—Dynamic Metamorphism of Skiddaw Slates. Dr. F. H. Hatch.—On the Lower Silurian Felsites of the South- Fast of Ireland. A. R. Hunt.—The Age of the Granites of Dartmoor and the English Channel. R. Swan.—The Island of Paros, in the Cyclades, and its Marble Quarries. Prof. T. G. Bonney.—Preliminary Note on the alleged Occurrence of Fossils in the Crystalline Schists of the Lepontine Alps. W. W. Watts.—To exhibit Specimens of Belemnites from Lukmanier. Prof. T. G. Bonney.—Effects of Pressure on Crystalline Limestone. J. J. H. Teall.The Amygdaloids of the Tynemouth Dyke. Dr. F. Nansen.— Greenland. Prof. C. Williamson.— Report on Coal Plants; on the Present State of Inquiry into the Microscopic Features of the Coals of the World, and into the Organization of the Fossil Plants of the Coal-Measures. Prof. T. Rupert Jones.—Report upon the Fossil Phyllopoda of the Paleozoic Rocks. Dr. H. J. Johnston-Lavis.—Report on the Volcanic Phenomena of Vesuvius. Prof. E. Hull.—To exhibit Specimens of supposed Coral Structures from Culdaff in Donegal, and to invite opinions thereon. Prof. HE. Hull.—TYo exhibit a small block of magnetically polar diorite. A. C. G. Cameron.—Note on the recent exposures of Kellaway’s Rock at Bedford. G. R. Vine-—Polyzoa of the Red Chalk. W. A. #. Ussher.—The Devonian Rocks of Great Britain. John Marley and Professor G. A. Lebour.—Sketch of the Rise and Progress of the Cleveland and South Durham Salt Industry, and on the Extension of the Durham Coal-field. C. EH. De Rance.—Report of the Committee on the Circulation of Underground Waters. - List of Papers read on Geology, 1889. 479 Dr. D Embleton.—On the Spinal Column of Lozomma Allmanni from the Northumberland Coal-field. Dr. R. Laing.—The Bone Caves of Cresswell, with the recent dis- covery of an Extinct Feline (Felis brevirostris) new to Great Britain. Dr. Rk. H. Traquair—On the Devonian Fishes of Canada. A. Smith Woodward.—On the Occurrence of the Devonian Ganoid Onychodus in Spitzbergen. A. Smith Woodward.—Notes on some new and little-known British Jurassic Fishes. (See page 448.) Prof. A. W. Riicker and Prof. T. E. Thorpe-—On the Relation between the Geological Constitution and the Magnetic State of the United Kingdom. Prof. A. C. Haddon.—Notes on the Geology of Torres Straits. _ G. W. Lamplugh.—Report on an Ancient Sea Beach near Bridlington. Dr. H. W. Crosskey.—Report on Hrratic Blocks. W. Whitaker.—On a Deep Channel filled with Drift in the Valley of the Cam, Essex. H. H. Howorth.—Are the extreme Glacial Views developed by Agassiz and his scholars consistent with our Present Geological Knowledge ? G. W. Lamplugh.—Note on a New Locality for the Arctic Shell-beds of the Basement Boulder-clay on the Yorkshire Coast. H. H. Howorth.—Did the great Rivers of Siberia flow Southwards and not Northwards in the Mammoth Age? &. B. Dorsey.—On the Witwatersrand Gold Fields. A. Bell.—Report on the Manure Gravels of Wexford. Prof. F. Clowes.—On Waterbox Deposits and their Bearing on the Cementing Material of Rocks. J. Starkie Gardner.—Report on the Hocene Plants of the Isle of Wight. Prof. "4, El. Green.—A word or two about the so-called Concretions in the Magnesian Limestone of Durham. W. Topley.—TVhe Work of the Geological Survey in Northumberland and Durham. R. Tiddeman.—On Concurrent Faulting and Deposit (Craven, York- shire), with a note on Carboniferous Reefs. List of Papers bearing on Geology read before other Sections. Section A. (Mathematical and Physical Science.) Report of the Committee on Underground Temperature. Section B. (Chemical Science.) J. Pattinson ee Dr. H. S. Pattinson.—On Chilian Manganese Ore. Prof. Frank Clowes.—On Barium Sulphate Deposits from the Waters of Durham Coal-mines and in Nottingham Sandstone. Report of the Committee on the Formation of a Uniform System of Recording the Results of Water Analysis. Section D. (Biology.) Prof. H. F. Osborn.—The Paleontological Evidence for the trans- mission of acquired characters. 480 Correspondence—Captain Marshall Hail, R. Irvine and G. Sims Woodhead.—On the Secretion of Carbonate of Lime by Animals. W. 8S. Anderson.—The Solubility of Carbonate of Lime in Fresh and Sea Water. Dr. Traquair.—Restoration of Asterolepis maximus (Agassiz), with remarks on the Zoological affinities of the Pterichthyide. Section E. (Geography.) Joseph Thomson.—Report to the Committee appointed to investigate the Geography and Geology of the Atlas Ranges in the Empire of Morocco. W. J. Flinders Petrie—Wind Action in Egypt. Section F. (Economic Science and Statistics.) Prof. Edward Hull.—The State of our Coal Resources. Prof. Edward Hull.—Diagram showing the rate of Production of Coal during the present Century. Section G. (Mechanical Science. ) 0. E. De Rance.—Records of River Volumes and Flood Levels. CORES Oi» 7 aNi@ ae ——.__ Sir,—So many of your readers must go Alp-wards that I appeal, though late, to any who may visit the Chamounix district, to help me in a little investigation by looking out for diorites about the junction of the gneiss with the protogine—the inner portions of de Saussure’s “Artichoke.” I am prevented from doing so myself this year. Last summer I picked up a worn pebble in the gorge below Pierre a l’Hchelle, and above Pierre Pointue, both mere cockney points of interest on the way up Mont Blane. I do not remember any mass of diorite thereabouts. But it appears at intervals from the Mottets! to the upper Grands Mulets. I did not climb in search, not having sufficient time left. My specimen proved to be an epidiorite, under the microscope, with slightly banded structure. Hornblende, not orientated, pro- bably of augitic origin, showed two periods, one, the older, giving the usual pleochroic green and yellow, the other nearly colourless, with a cement, so to speak, of the secondary hornblende. The cleavage continued through this portion. There is apatite, plagio- clase and a ground mass which I have not properly investigated. I feel sure that careful study would give interesting results if this contact-region were investigated. Something like what my section gives is shown in Teall’s grand book, at plate 17. The problem of at least two periods of formation of the hornblende points to an interesting history of the Mont Blane “Artichoke” formation period. Marsuatt Hatt. Grosvenor Crus, September, 1889, 1 The rocks exposed close to the Glacier des Bois and Mer de Glace. GEOL. Mac, 1889. DECADE III. Vou. VI. PL. XIV. To Lllustrate Mr. Teall’s paber on the Amyecdaloids of the Tynemouth Dyke. THE GEOLOGICAL MAGAZINE. NEW SERIES. DECADE Ill. VOL. VI. No. XI.—_NOVEMBER, 1889. ORIGINAL ARTICIHS:- Pee ne ill J.—On tHE AMYGDALOIDS oF THE TynEmMouTH Dyxz.! By J. J. H. Tear, M.A., F.G.S: (PLATE XIV.) N a paper published in the Quarterly Journal of the Geological Society for 1884,? I gave some account of the Tynemouth Dyke. In that paper, however, I omitted to describe one feature, connected with the microscopic structure of the dyke, because at the time of writing I did not understand it. A short time ago I had occasion to re-examine my preparations, when my attention was again directed to the feature in question; and this time an explanation suggested itself which appears to be in every respect satisfactory. The main object of this communication is to supplement my already published description by giving an account of the feature to which I have referred, and which may be briefly described as the occurrence of spherical patches of interstitial matter. (See Pl. XLV. Fig. 1.) At the time of my residence at Tynemouth (1882) the dyke was exposed in the angle formed by the breakwater and the cliff on which the Priory stands, and also in the cutting close to the railway station. The rock of which the dyke is composed varies somewhat in character owing to the presence or absence of porphyritic felspars and small spherical amygdaloids. A typical specimen may be said to consist essentially of porphyritic crystals, or rather crystalline ageregates of a felspar closely allied to anorthite, embedded in a dark, finely-crystalline ground-mass, composed of augite, lath-shaped felspars, and interstitial matter. Olivine has been detected in one or two slides; but it is not usually present. The porphyritic constituents undoubtedly belong to the earliest phase in the consolidation of the original mass of molten matter. They consist, as a rule, not of single crystals, but of two or more individuals. Where the individuals of one and the same group are in contact with each other, they exhibit no trace of crystalline form ;? but where they are in contact with the ground-mass, they are bounded by definite faces. In other words, the internal relations of the individuals forming a group are those of plutonic rocks (e.g. gabbro), whereas the external relations of the same individuals are those of volcanic rocks. This, of course, is in strict accord with the general view that the porphyritic constituents have been developed under plutonic conditions. An examination of the porphyritic aggregates 1 Read at the Brit. Assoc., Newcastle-on-Tyne, in Section C. (Geology), Sept. 1889. 2 Petrological Notes on some North of England Dykes, vol. xl. p. 233. 3 See fig. 1, plate xiii. accompanying the paper already referred to. DECADE III.—VOL. VI.—NO. XI. 31 482 J. J. H. Teall—Amygdaloids of Tynemouth Dyke. under crossed Nicols reveals the fact that the felspar-substance to which the external idiomorphism is due differs from that forming the central portions. This, taken in connection with the fact that the augite-grains of the ground-mass are occasionally included in the peripheral zone of the porphyritic groups, justifies the conclusion that such external form as the individuals possess was given to them at a later stage in the history of the consolidation of the rock than that at which the groups themselves were formed, and also under different physical conditions. The augite is pale in colour, and occurs in grains or granular aggregates. It is occasionally penetrated by the lath-shaped felspars, and must, on the whole, have been formed after them. The lath-shaped felspars call for no special description. They frequently show multiple twinning of the usual type. The interstitial matter contains extremely minute microlites and skeleton crystals of felspar, grains and skeletons of magnetite, and an indistinct brownish granular substance. It is not possible to recognize any true glass, even with the highest powers. ‘This interstitial matter occurs in more or less angular patches wedged in between the other constituents. and gives to the rock the structure for which Professor Rosenbusch has proposed the term intersertal. The rock itself would be termed by this author a tholeite. Now the peculiar feature to which I wish to call special attention is the occasional occurrence of spherical patches of interstitial matter. These appear in the thin sections—and they have only been recog- nized in the sections—as circles. How are these spherical patches to be accounted for? An answer to this question is found by studying ~ the amygdaloids, which have been already referred to as occurring in certain portions of the dyke. (See Pl. XIV. Fig. 2.) Microscopic examination enables us to determine the precise stage in the history of consolidation at which the vesicular cavities, now for the most part filled with carbonates with or without a narrow border of chalcedony, were formed. Their development evidently displaced the lath-shaped felspars, for these are often arranged tangentially with reference to the bubbles; but it produced no efiect on the disposition of the constituents of the interstitial matter. It appears, then, that the gas bubbles were produced after the formation of the porphyritic constituents, the augite and the lath- shaped felspars, but before the consolidation of the interstitial matter. It is possible that their development was due to the relief of pressure consequent on the rise of the semi-liquid mass in the crack. If so, then they are analogous, so far as their mode of formation is con- cerned, to the bubbles which arise in the contents of a soda-water bottle as the cork is partially removed. Now, the spherical patches of interstitial matter agree in form and size with the amygdaloids, and to account for them we have only to suppose that the portion of the mass which was liquid at the time of their formation, oozed into some of the vesicles owing to the absorp- tion, escape, or condensation of the gas. That this is the true expla- nation is proved by the occurrence of cavities which have been only Prof. T. G. Bonney—Effects of Pressure on Limestones. 483 partially filled up. (See Pl. XIV. Fig. 3.) The last act to which we have to call attention was the filling up of the cavities remaining “empty after final consolidation with chalcedony and carbonates. We may summarize the history of the rock so far as it is recorded in microscopic structure as follows :— 1. Development of granular aggregates of a felspar allied to anorthite under plutonic conditions. . Addition of felspar substance to the external portions of the granular aggre- gates, and the consequent production of crystalline form. . Development of lath-shaped felspars. 4. Separation of augite. . Formation of vesicles owing to the separation of gas from the magma. . Partial or complete fillimg up of some of these vesicles with interstitial matter. . Consolidation of the interstitial matter. [carbonates. . Filling up of the vesicles remaining empty after final consolidation with EXPLANATION OF PLATE XIV. Augite is indicated by dots, interstitial matter by lines. The felspar is left clear. 'Magnetite is black. Fie. 1. Vesicle filled with interstitial matter. » 2 45, ~ filled with carbonates. » 98 4, partly filled with interstitial matter and partly with carbonates. CIO Oreo bo I].—Tas Errrcts or Pressure ON ORYSTALLINE LimestTonss.! By Prof. T. G. Bonney, D.Sc., LL.D., F.R.S., F.G.S. far who have carefully studied the crystalline schists cannot fail to have noticed that a community of structure—a sort of family likeness—prevails throughout any one group of rocks, while those which occur apparently at different horizons exhibit dissimilar structures. Thus the marbles associated with any group of crystalline schists are coarse or fine in grain, according to the structure of the latter. But to this rule exceptions appear, at first sight, not infrequent. For instance, in the Alps, we find not un- commonly, in that group of schists which seems to occupy the highest position, marbles which present an abnormally compact aspect. On closer examination they prove indeed to be crystalline in structure, but the crystals seem so small, the general structure so compact, that until we find them graduating into typical mica or other schists, we can hardly feel satisfied we are not being duped by infolded limestones of Mesozoic or Paleozoic age. When, however, we study the microscopic structure of such crystalline limestones, the abnormality proves to be more apparent than real. This compact structure is due, not to the absence of crystallization, but to the destruction by pressure of an original crystalline structure: for we find on examination that the rock, once perhaps coarsely crystalline, has been crushed and again consolidated, so that it has now assumed a comparatively compact appearance. A proof of the above statement may be afforded by a brief description of the structures which are exhibited by a series of limestones * which J have from time to time collected and examined. 1 Read before Section C, Brit. Assoc. Newcastle-upon-Tyne Meeting, Sept. 1889. 2 Many of the Alpine limestones, both in the Mesozoic and in the Crystalline series, are more or less dolomitic, but I have not thought it necessary to distinguish these. The statements apply to both, except that, among the ordinary sedimentaries, the 484 Prof. T. G. Bonney—LEfects of Pressure on Limestones. In the Alps, as is well known, large masses of limestone occur which are indubitably of Mesozoic age. Sometimes these have been exposed to great pressure; sometimes they appear to have been uplifted with comparatively little disturbance. In either case there does not appear to be a very marked difference in their crystalline condition. A Mesozoic Alpine limestone may be described in general terms by saying that it resembles, often closely, in texture and sometimes even in colour, one of the Carboniferous limestones of Britain—that is to say, it varies from black to grey—though the peculiar light grey of the English Carbonifeous limestone is, so far as I know, most unusual. Not seldom the rock is yellowish in colour, like some of our Mesozoic limestones, but with a different texture ; occasionally it is reddish. Even where the calcareous constituent exhibits a crystalline character, it is obvious that, if this were removed by the action of an acid, the residue would be, roughly speaking, mud, silt, or sand which, as a rule, has not undergone more alteration than would be observed in the above-named British rocks. If, however, we examine a limestone which both is in- dubitably associated with a series of crystalline schists and has been selected from a comparatively undisturbed region, we find that whether coarse or fine (in the latter case of course the statement may be less precise) the constituents throughout are in a crystalline condition. If quartz-grains are present, they bear no resemblance to those in a sandstone, but have evidently assumed their present outline in siti.’ If mica, it is in like way evidently authigenous. So also with the malacolite, sahlite, or other mineral constituents. In short, it is evident that, whether the rock were originally an organic aggregate, a chemical precipitate, or a detrital accumulation, the constituents have undergone a molecular rearrangement, which is in all cases considerable and is often complete. If now we turn from the examination of such specimens to one of the abnormal-looking limestones, collected from a crystalline group which has been exposed to severe pressure, we find that its constituents, as before, are in a crystalline condition, but that the structure of the rock is different. Instead of finding a considerable uniformity in the size of the calcite grains, we observe a marked diversity. In a ground-mass of granules are scattered grains variable in size and number, subangular or slightly irregular in outline, and sometimes exhibiting a slightly linear arrangement. If an outline sketch were made of the slide, it might be supposed to represent a subangular breccia or conglomerate—except that the outline of the larger grains is slightly irregular or ‘ragged.’ Further, many of these grains exhibit the twin lamellz, which, as is well known, can be artificially produced in a calcite crystal by pressure, and which, if they occur in rocks, are now commonly ‘dolomites’ generally have a more crystalline aspect, and, among the crystalline schists, do not usually show mineral cleavage so readily as those which only contain calcite ; they also exhibit the usual differences to which I called attention in 1879 (Q.J.G.8. vol. xxxy. p. 167). 1 Of course they may have had a clastic nucleus, but of this their present outline shows no trace. Prof. T. G. Bonney—Effects of Pressure on Limestones. 485 regarded as indicative of the same disturbing cause.’ Not seldom there seems to be a tendency to orientation in these lamelle, since they either lie in or make angles of about 20° with the rude planes of incipient cleavage in the rock; these, of course, being roughly perpendicular to the direction of pressure. The well-known crystalline limestone of Tiree is an interesting example of the same process. This rock was for some time a puzzle to me, for the large size of the sahlite grains, which were such as might be expected from the geological position of the rock, seemed to be incongruous with the apparently compact calcareous matrix. One would have expected the latter to resemble the crystalline calcite in one of the malacolite limestones in the “Granville series” of Canada. But an examination of a set of slides prepared from specimens of the Tiree rock has removed the difficulty. The brecciated or conglomeratic structure above described is at once revealed by the microscope. Grains of calcite, of various sizes, in some cases almost as large as those of the sahlite, are scattered about in a finely granular matrix of calcite, which gives the usual indica- tions of having suffered from pressure, although subsequently it has been completely reconsolidated. On closer examination, we find here and there a grain of calcite, either occupying an inlet in one of the sahlite grains or sheltered between two adjacent grains of the same, which has evidently formed part of a larger grain, and which indicates that the calcite matrix was once in a coarsely crystalline condition and that its grains corresponded in magnitude with that of the sahlite. In one case that I have examined the accidental proximity of some sahlite grains has so protected the calcite that two or three crystals of it remain unbroken, and we can, as it were, study a fragment of the original rock. Jn one instance, adjacent to an unbroken grain of calcite, are some of much smaller size, which, in their relation to the matrix and their disposition, suggest that an original grain, thus imperfectly protected, has been broken up but not crushed. The matrix of the slide consists of calcite granules, in which a faint streaking is seen, suggesting the action of pressure. It is remarkable that the sahlite grains do not appear in my specimens to be broken or even distorted. Probably they have been saved by the easy cleavage and brittleness of the calcite, which was reduced to a powder by the pressure, and again consolidated as the latter diminished. Miss C. A. Raisin has recently shown me a specimen, collected by herself, in which the effect of pressure on calcite is well illustrated. It is a brecciated volcanic rock (? andesite) from Porth Oer, north of Aberdaron, the fissures in which have been filled up by calcite with a little quartz. In consequence of subsequent pressure the quartz is displaced and shows strain-shadows, but the calcite exhibits various stages of crushing, as described above, most of it being reduced to granules, and these sometimes are slightly ‘streaky’ in their arrangement. Here then the history of the rock is complete and there can be no doubt as to the cause of the structure. Hence the observations—and they have been rather extensive— 1 Rutley, Rock-forming Minerals, s.v. Calcite. 486 Dr. FE. Naumann—Magnetism and Earth Structure. which have been briefly summarized above, lead me to the following conclusions : 1. While I would not venture to affirm that pressure has no effect in producing crystallization in a limestone, this is only small and subordinate, quite insufficient as a rule to obliterate the ordinary character of a limestone, such as occurs in strata of later Palaeozoic or of Mesozoic age. Certainly, as is shown by the study of limestones into which igneous masses have been intruded, the effects of pressure are far less marked than those of heat, under circumstances which appear to be otherwise similar. 2. When limestone already crystalline has undergone severe pressure, its structure, macroscopically and to a considerable extent microscopically, is rendered less coarsely crystalline, i.e. instead of be- coming more distinctly crystalline, it is made to resemble more nearly an ordinary limestone (non-oolitic and unfossiliferous) such as might be obtained in Derbyshire, in South Devon, or in many parts of the Alps. Perhaps I should add that I am fully aware that some geologists, whose opinion is entitled to respect, have recently asserted that certain crystalline limestones in the last-named district are Jurassic rocks which have been altered by pressure. The typical instance of this, as it may be called, has long been known to me, and has been recently examined anew. It will take some time to complete the study of the specimens which have been added to my collection, and until that is done, I will say no more than that this identification appears to me an hypothesis, in support of which only a little and against which very much evidence can be adduced. Indeed, as I hope to show in a paper now nearly completed, which will include the results of this and other work in a like field, the direct effects of pressure are rather destructive than constructive— a matter which I think has sometimes been overlooked in specula- tions on ‘pressure-metamorphism.’ It is but a part of a chain of sequences, though here also it may be true that (to speak figura- tively) “mille animas una necata dedit.” IIJ.—Trrrestria, Macyerism as Mopiriep By THE STRUCTURE OF THE Hartu’s Crust, AND Proposats Concerning A MaGnetic SURVEY oF THE GLoBs.! By Dr. Epmunp Naumann. “TT\HE study of any new science,” says Alexander v. Humboldt, “may be compared to a journey to distant lands. Before starting in company with others, the question as to the practicability of the journey is raised; while examining one’s own powers, the qualities of fellow-travellers are looked upon with distrust. It is feared—perhaps without just reason—that they might cause un- pleasant detention. In our time the difficulties of an undertaking of this kind are much diminished. Any confidence is founded on the bright blossoming state to which natural sciences have grown, their wealth being no more the abundant quantity, but the concatenation of what has been observed.” 1 Read at the Brit. Assoc. Newcastle, before Section C (Geology), Sept. 1889. Dr. E. Naumann—Wagnetism and Earth Structure. 487 These remarkable words were spoken nearly half a century ago. Since then natural sciences have undergone enormous development, many methods of investigation have been completely changed, and the aim of concatenating facts has greatly influenced the methods of obser- vation. Systems which were then descriptive have been replaced by others in which the various facts are arranged, so as to exhibit their relation to causes, and by reducing the number of isolated facts, differ- ent fields of investigation have been brought into closer relationship. The change which has taken place is particularly striking in the case of Mineralogy. Modern mineralogists devote considerable at- tention to Physical Crystallography, a study which borrows its methods from a sister science, and the results attained by the combination are very satisfactory. By the aid of light we are enabled to discern the structure of crystallized bodies, ‘and to trace the marvellous connection between ‘composition, structure, and form. The motions of light, although the best, are not the only means of investigating internal structure, for those of heat, electricity, and magnetism, also depend on the shape, size, and arrangement of the smallest particles and their interstices. Any interposition, any fissure, causes changes of wave motion, for this motion can only be propagated regularly in homo- geneous media, and its character, velocity, and direction of propa- gation are altered wherever any variation from homogeneity exists. Changes of this kind occur even at the planes of composition of twin crystals, where no alteration of substance, but a mere change of structure, takes place. In the same way, the electric currents passing through the earth’s crust must be diverted, or accelerated, retarded, or modified, wherever the uniformity of composition is interrupted. Such interruptions will be caused by deep fissures, once open at the surface and leading towards the earth’s interior. These clefts cannot generally be found by direct observation, but require the aid of geological research. At the present day, probably the majority of physicists consider the globe to be a body of very uniform composition or structure, and though it is generally admitted that there is a change of structure radially, the irregularities which divide one and the same of the pre- sumed concentric layers into unequal parts, are generally neglected, although geology has proved the predominance of such irregularities in the earth’s crust. Modern geology no longer accounts for the differences between observed and calculated polar altitudes by assuming constant errors, the compensation of which is effected on the method of Least Squares. We know that the earth is irregular in form, and that its shape cannot be expressed by any mathematical equation. The so-called geoid is not geometric in form, and there is in fact an infinite number of geoids. These discoveries have greatly limited the application of the method of Least Squares. Irregularities exist not only in the form of the earth, but also in the distribution of matter, and precautions are just as necessary in physiographical researches as in geodetic investigations, if a mathematical compensa- 488 Dr. £. Naumann—Magnetism and Earth Structure. tion of errors is to be attempted. Though errors of observation cannot be avoided, there is no doubt that in many cases deviations from a certain expected result are not due to errors, but to actual irregu- larities presented by nature. These deviations were formerly referred to accidental causes or to local influences, and the unexpected results were considered anomalous and disappointing; and even up to the present day it has been customary to arbitrarily modify results which do not agree with mathematical formulas, and to constrain curves that would not otherwise have exhibited the expected regularity. The earth’s crust is considerably broken and fissured, and its superficial layers folded; these disturbances must have some influence on the phenomena resulting from the motions which we call heat, electricity, and magnetism. Of these forces, magnetism is the one most useful in the study of the earth’s structure, and just as optical phenomena are employed in researches on the internal structure of crystals, those of magnetism may be used to investigate the internal structure of the globe. Magnetic phenomena may be regarded as telegraphic messages from distant depths, but, unfortunately, in the present state of science, it is impossible to decipher them. In a memoir entitled “The Phenomena of Terrestrial Magnetism in their Dependence upon the Structure of the Earth’s Crust,’? I have given a large number of instances in which the distortion of magnetic curves are caused by clefts in the crust, and have pointed out that the isogonic lines afford the clearest indications of a con- nection between magnetic and structural conditions. The ‘isogones ’ are much more important than the magnetic meridians; this will be easily understood as soon as electricity and magnetism are considered to be different manifestations of one and the same force. From recent investigations made in Germany it is highly probable that an intimate connection exists between Earth Currents and Terrestrial Magnetism, and if this be true, deviations in the direction of the currents ought to be accompanied by changes of declination. For such reasons I consider the Isogones to be the best indicators of the course of the earth-current. The systems of magnetic curves show very distinctly a relation to mountain ranges, faults, eruptions, and tectonic disturbances, wherever a detailed magnetic survey has been made. Irregularities in the curves are so frequent that their existence could not be denied even at the very beginning of magnetic surveying; however, they were not attributed to want of internal uniformity of the globe, but to the influence of magnetic masses at or near the surface, to denote which, the special name ‘“‘ Rock Magnetism” was introduced. There are magnetic rocks at the surface. and almost any kind of rock, such as Serpentines, Granites, Syenites, Porphyries, Diorites, Trachytes, Andesites, Basalts, etc., may act on the needle, but there are no magnetic rocks below the surface! Even magnetic iron ore does not show a trace of magnetism directly after it is taken from the mine, 1 Die Erscheinungen des Erdmagnetismus in ihrer Abhiangigheit von Bau dei Erdimde, Stuttgart, 1887 Dr, E. Naumann—Magnetism and Earth Structure. 489 ‘but the magnetic property is developed after being exposed to the atmosphere for some time. In the above-mentioned memoir I have endeavoured to prove that the so-called “rock magnetism” does not produce the distortion of magnetic curves, and J here quote one example to show how insigni- ficant these local disturbances are. The long chain of mountains, Katschanar-Blagodat-Wissakaja Gora of the Ural, consist chiefly of magnetic iron ore, and although the compass is strongly affected in the immediate neighbourhood of the ore in the quarries, yet the chain produces no remarkable distortion in the system of magnetic curves. Other examples might be given to show that “rock magnetism” is a secondary phenomenon confined to the very surface of masses, and not a property of the masses themselves. Moreover, the surfaces of rocks which exhibit magnetic properties, generally present a con- siderable number of irregularly distributed poles. The connexion between magnetic and structural phenomena was foreseen by several distinguished observers. It was on the 26th of May, 1849, that Kreil read his paper “‘ On the Influence of the Alps on the Reactions of the Magnetic Force of the Harth.”! He was not clear about the tectonic relations, but knew with certainty that some connexion existed between magnetic phenomena and the internal condition of the earth’s crust, and that the cause of mountain ranges had considerable influence on the direction of the magnetic curves. At a still earlier date Locke communicated his paper to the American Philos. Soc. of Philadelphia? In it, many interesting observations were made which might have been followed with advantage, but unfortunately his work, like that of many others, was forgotten. He surveyed magnetic profiles, and plotted inclination curves having distances as abscisse and “magnetic dips” as ordinates. The curve for the line passing over the horizontally stratified rocks of the West, through Kentucky and Ohio, and along the Mississippi, shows generally a very gradual rise until it crosses eruptive rocks between Baltimore and New York, where it exhibits a rise and fall ‘like the contour of primitive or igneous mountains.” (See Plate XV. Fig. 1.) ° Many extensive surveys have been made since Humboldt and Gauss brought the subject into prominence, but there have been few observers who were not somewhat embarrassed by the mathematical theory of Gauss, and nearly all have considered the irregularities in magnetic charts as something accidental, anomalous and vexatious. The recent activity in magnetic surveying is very gratifying, but many observers still use the old methods, although they are capable of considerable improvement. The rate of progress could be further accelerated by establishing ' Denkschriften der Kaiserlichen Akademie der Wissenschaften. Mathem. natur- wissench. Klasse. Bd. I. Wien, 1850. 2 Locke, Observations of the Magnetical Force in several parts of the United States. Trans, Am. Phil. Soc. of Philadelphia, vol. ix. 1846, p. 283. * The Plates illustrating Dr. E. Naumann’s paper will accompany Part II. in December Number Grou. Mac.—Epir. 490 Dr. R. H. Traquair—On the “ Dendrodont’”? Fishes. and following a general scheme for a Magnetic Survey of the whole globe, and united efforts might considerably reduce the labour involved in so great an undertaking. It is very desirable that such a systematic and complete survey should be taken in hand, instead of giving particular attention to limited districts, and I solicit the help of those interested in the subject, in starting an undertaking in which we may be sure that all nations will gladly join. (Lo be concluded in our next Number.) IV.—On rue Systematic Posrrion oF THE “DENDRODONT” FISHES. By Dr. R. H. Traquatr, F.R.S., F.G.S. : N a short paper on the nomenclature of the Old Red Sandstone Fishes published in this Magazine for November, 1888, I expressed the opinion ‘that the scattered teeth and fragments of jaws known as Dendrodus and Lamnodus belong to fishes at present known to us by their scales as species of Holoptychius and Glyptolepis.” The family terms “ Holoptychiide” and ‘ Dendro- dontides” I consider absolutely synonymous. On the other hand, the Rhizodontide (Gyroptychius, Tristichopterus, Rhizodus, ete.) present a somewhat different form of tooth-structure, and one which is, in the main, identical with that which, in so many Stegocephalous Amphibia, is called “ labyrinthodont.” The reasons in support of this opinion are something considerably beyond the region of conjecture, —they amount to positive proof. As far back as 1849, Hugh Miller? figured portions of jaws with teeth, as well as microscopic sections of teeth from Thurso, which are undoubtedly referable to Owen’s genus Dendrodus, both as regards external configuration and internal structure. Of this Miller was aware, though he refers them to Asterolepis, Hichwald, along with the large cranial shields and other remains of a great coccostean fish, Homosteus of Asmuss. Now nothing can be more certain than that these dendrodont teeth from Thurso belong to a large species of Glyptolepis, in more than one head of which, belonging to the Edinburgh Museum, they may be seen in situ. This Glyptolepis is also identical with Agassiz’s “ Platygnathus” paucidens. As regards the very closely allied Upper Old Red genus Holopiychius, I have not obtained any microscopic sections of teeth found in situ; but, to judge from the external characters of these teeth, as seen through a good hand-lens, it is impossible to doubt their dendrodont nature. And finally the portions of jaws which occur displaying teeth of “* Dendrodus” are undoubtedly Holoptychian in their con- figuration. Now, the occurrence in the Holoptychiide: of pectoral fins dis- playing the ‘“archipterygeal” configuration clearly enough shows that there must be some genetic connection between this family and the Dipnoi. I was therefore interested to read in the introduction to a recent paper on this subject? by Dr. J. V. Rohon that the 1 Footprints of the Creator, first edition, 1849, figs. 30, 31, 32 and 33. * Die Dendrodonts des devonischen Systems in Russland, Mem. Acad. Imp. Sc. St. Petersbourg (vii.) vol. xxxvi. No. 14, 1889. Dr. R. H. Traquair—On the “ Dendrodont” Fishes. 491 “ Dendrodonts ” do not belong to the Ganoidei, but to the Dipnoi, as he had been able to prove the autostylic condition of the skull—“ d.h. das mit dem Schidel unbeweglich verschmolzene Palatoquadratum und das verkiimmerte Hyomandibulare.” On reading the paper, however, and examining the two very pretty plates by which it is illustrated, _ one is rather disappointed as to the evidence which Dr. Rohon has adduced to prove his position. It is of course not always easy to identify every part of a fossil fish skull from drawings only, but there are a few points concerning the fossil figured by Dr. Rohon as the ‘‘skull” of Dendrodus biporcatus which are self-evident. This “skull” (pl. i. fig. 1) is not the entire skull, with several body-vertebrae fused with it, as Dr. Rohon seems to imagine, but only the anterior part or snout broken off near the interorbital region. His “pterygo-palatine” bones are the two elements of the duplex vomer, each of which, as in the Rhizodonts and Saurodipterines, bears one or more large tusks. The skull being broken off quite anterior to the brain-cavity, it will hardly be appropriate to designate anything here displayed as ‘‘quadrate” or “ hyomandibular,” the parts so lettered being in reality ante-orbital in position! What Dr. Rohon interprets as orbit (though indeed with a query) is a crevice apparently at the postero-external part of the premaxilla. Dr. Rohon seems to put great weight on the ‘“einheitlichen Hautknochen ” by which the “Schadeldecke” is represented. The fusion of the dermal plates of the snout with the premaxille into one piece is not, however, a very rare phenomenon in Devonian Crosso- pterygii, and is indeed well seen in a large skull of Glyptolepis paucidens in the Edinburgh Museum. In fig. 8 Dr. Rohon represents a broken-off snout which he refers to a new species of Cricodus (C. Wenjuckowi). Here the supposed “orbits” have a most suspicious resemblance to nasal openings. The orbits in many old fossil fishes are anterior enough, it is true, but not quite situated upon the very front of the snout itself. In fig. 10 Dr. Rohon has given a view of a dentigerous fragment from Thurso which he supposes to be a part of a skull of Dendrodus showing the cranial cavity. As the diameter of the supposed cranial cavity is not greater than that of the base of the large tooth attached to the specimen, this interpretation can hardly be correct. Nor can I admit that the dentigerous fragment depicted in his fic. 11 represents the entire mandible either of Dendrodus or any other fish. I think also that Dr. Rohon is hardly entitled to explain the discrepancies between this fragment and the mandibles, figured by Pander, Trautschold and Agassiz, on the supposition that they belonged to fishes which, though “allied to the Dendrodonts in the structure of their teeth, were tolerably far removed from them as regards the constitution of the lower jaw, and probably also of the skull.” At the end of the paper he gives an “attempt at a restoration ” of Dendrodus biporcatus, Owen. Here the body and fins are formed as in Gyroptychius, and, if the author considers Dendrodus to be a 492 Dr. J. 8. Hyland—Zonal Structure in Olivine. Dipnoan, it is certainly strange that he should represent it with the obtusely lobate pectorals of the Rhizodonts and Osteolepids instead of with the acutely lobate or unabbreviate archipterygeal members of Ceratodus or Dipterus. Except the mandible, no bones are marked off on the head, in accordance with the idea that the cranial roof is represented by a single dermal bone, while near the end of the snout are placed two minute orbits. It is to be hoped that no future compilers of geological or paleeontological text-books will copy this extraordinary figure and insert it as a ‘restoration of Dendrodus.” As the result of his researches Dr. Rohon announces that the genera Dendrodus, Owen, and Cricodus, Agassiz, are not Ganoids, and considers that they should be reckoned as forming a peculiar order of Dipnoi. Of this supposed “order” he gives the following definition :—‘‘ Fishes with depressed head, whose surface-ornament consists of ridges and tubercles. The free margin of the snout is set with numerous small teeth, whose folded dentine encloses a Spacious pulp-cavity. Two powerfully developed palatal teeth, which are intimately united with the pterygo-palatine, and within the folded dentine contain a spacious pulp-cavity; they are placed asymmetrically. The bony quadrate is fused with the skull. A styliform parasphenoid displays on its surface a tract of little tubercle-— like teeth, and is the bearer of several fused vertebrze, drawn into the skull. Very small orbits (?) and two internal nasal openings are present. The skull-roof represents a simple dermal bone, whose histological structure corresponds to that of true osseous tissue.” Now as this definition is founded upon an entire misinterpretation of the specimens figured in the paper, I fear it can only be looked upon as a curiosity of scientific literature. Whatever relationship “ Dendrodus” may have with the Dipnoi, it is certainly not in the manner indicated by Dr. Rohon, and I for one do not as yet see any reason for separating the Holoptychiide, of which I consider “‘ Dendrodontide ” to be a simple synonym, from the Crossoptery- gian Ganoids. Again, I must refer to my paper on the nomenclature of the Old Red Sandstone fishes with regard to Cricodus, which Dr. Rohon also includes in his Dendrodont Dipnoi. If Pander’s Polyplocodus be Synonymous with Agassiz’s Cricodus, then the latter is certainly not a Dendrodont or Holyptychian, but a Rhizodont. V.—On Zonat Srructure in OLIVINE. By J. SHearson Hytanp, Ph.D., M.A., Of Her Majesty’s Geological Survey. N a recent paper on the volcanic rocks of Kilimandjaro I referred to the presence in the basaltic lavas of olivine crystals, which appeared to possess zonal structure. Although actual proof was wanting, still the symmetrical arrangement of the inclusions, as also the mode of alteration of the crystals, rendered the occurrence of such a structure highly probable. The olivines, being rich in iron, were altered into ferric oxide or ferric hydrate; and the line of Dr. J. 8. Hyland—Zonal Structure in Olivine. 493 division between the fresh and decomposed portions was mostly parallel to the crystallographic outlines.’ There was, however, no break in the optical continuity, such as the presence of zonal structure would demand. A microscopical examination of some similar rocks from the same locality has led to the gratifying discovery of true evidence of zonal structure in this mineral. Fig. 1 shows a corroded olivine exhibiting this phenomenon. The inner zone is shaded in _ order to graphically represent its outline with ug L. reference to the contours of the crystal. The zones are dissimilar in their optical behaviour, the difference between their extinction-angles being as much as 6°. In transmitted light there is a trace of the structure apparent; the upper line of division being a plane of fracture, the lower being marked by glass inclusions. The literature on the subject is not extensive. Van Werveke, in 1879, seems to have been the first to suggest the possible occurrence of zonal structure in this mineral. In his paper on the Palma basalts he mentioned the presence in this constituent of glass inclusions, which were arranged parallel to the crystallographic outlines. This induced him to expect zonal structure.? In the same year Hofmann formed a similar opinion as the result of his observations of the presence of “zones which were different in their optical characters and in their manner of alteration.” * Bruno Doss, in his paper on Syrian basalts, described and figured olivines composed of concentric layers, but was able only in one instance to note a variation in the polarisation tints. Stock has also mentioned a similar experience.® I fail, however, to find any instance recorded where the difference in the extinction-angles was so great as to allow of its accurate determination. Crystals grow by accretion, that is, by the addition of matter to their external surfaces. If this addition be regular and constant, the crystal formed will be a correct type of the species. But, if the growth be intermittent, complications will arise. In this respect a crystal is like a living organism: it is affected by its environment. The crystal modifies its surroundings, and is in turn modified by them : there is action and reaction between it and its environment. Inter- mittent growth must, accordingly, tend to produce zoned structure. In the case of isomorphous mixtures like augite and felspar this 1 “Ueber die Gesteine des Kilimandscharo und dessen Umgebung.’’ Tschermak’s Mittheilungen, 1888, vol. x. pp. 224 and 226; also plate vii. fig. 2. 2 The mineral gives reactions characteristic for olivine. 3 « Beitrag zur Kenntniss der Gest. d. Insel Palma.’’ Neues Jahrbuch fur Mineralogie, etc., 1879, p. 820. 4 «Die Basaltgest. des stidlichen Bakony,’’ Budapest, 1879, pp. 27 and 198. > <¢Die basaltischen Laven und Tuffe der Proyinz Hauran, etc.,’’ ‘I'schermak’s Mitt. 1886, vii. p. 488; plate ix, fig. 32. 6 «Die Basaltgest. des Lobauer Berges,’’ Tschermak’s Mitt. 1888, ix. p. 487; and plate ix. fig. 2. 494. UM. Foord & Crick—Shell-muscles of Ceelonautilus, ete. tendency is particularly strong, and usually leads to the construction of crystals built up of innumerable layers, different in chemical constitution and often so fine as to require the microscope for their detection. Since olivine represents an isomorphous mixture of Mg? SiO* and Fe® SiO*, it should be equally liable to this structure, and the poverty of observations on the point seems all the more remarkable. If the outline of the inner zone be studied, decided evidence of its corrosion through the fluid magma, previous to the deposition of the outer shell, will be observed. This alone is proof of the two zones representing different periods of growth. The corroded form of this inner zone reminds us of the analogy existing between a erystal and an organism in manner of growth. The influence of the environment has already been referred to; but the regeneration of lost or injured parts? is also common to both. M. L. Pasteur has particularly studied this property in crystals. He refers to the process as follows: “Quand un cristal a été brisé sur l’une quel- conque de ses parties et qu’on le replace dans son eau mére, en méme temps quil s’agrandit dans tous les sens par un depdt de particules cristallines, un travail trés-actif a lieu sur la partie brisée ou deformée, et en quelques heures il a satisfait non-seulement 4 la régularité du travail général mais au rétablissement de la régularité dans la partie mutilees. 2.2 La partie endommagée reprend peu & peu sa forme primitive, mais la travail de reformation des tissus est en cet endroit bien plus actif que dans les conditions normales ordinaires.” * Applying these observations to the case under consideration, we conclude that, corrosion having ceased and the constructive process having recommenced, growth was more rapid at the corroded than at the uninjured part of the crystal. Consequent upon this special activity, regularity of form was re-established, and, ‘‘ regeneration ” having thus occurred, constant accretion completed the crystal. 14, Hume Srreer, Duswin. VI.—On tHe Muscunar Impressions or C@LonavUTILus ? CARINIFERUS> J. DE C. SowERBY, SP., COMPARED WITH THOSE OF THE RECENT NavrtiLus. By Artuur H. Foorp, F.G.S., and G. C. Crick, F.G.S. Te examining the remarkably fine series of examples of Ccelo- nautilus cariniferus, mostly from the Carboniferous Limestone of Treland, contained in the Geological Collections of the British 1 Ger. Reproduktion verletzter Theile. 2 « Etudes sur les modes d’accroisement des cristaux, etc.’? Compt. rend. tome 43, 1856, p. 795; see also, F. Scharff, ‘‘ Ueber die ausheilung verstiimmelter oder im Wachsen verhindert gewesener Krystalle, etc.,’” Pogg. Ann. vol. 109, 1860, p. 529 ; W. Ostwald, Lehrbuch d. allg. Chemie, Leipzig, 1885, Bd. i. p. 738; according to Scharff (l.c.) Jordan made an observation similar to Pasteur’s as far back as 1842 (in Miller’s Archiv.). y 3 This name from koiAov hollow (referring to the umbilicus), and Nawtzlus, is proposed by one of us in substitution for Zrematodiscus, Meek and Worthen, which MM. Foord & Crick—Shell-muscles of Colonautilus, ete. 495 Museum (Nat. Hist.), some were found to exhibit upon the cast of the body-chamber distinct marks of the shell-muscles. In one specimen (No. 50190) these are so perfect as to give a very clear outline of their form, and some of the test having been removed, their entire course can be made out. The accompanying Figures (A, B, D) show the appearance of these muscular impressions, carefully drawn of the natural size, from this specimen. mel i) | Celonautilus cariniferus, J. de C. Sowerby, sp., from the Carboniferous Limestone, Cork, Ireland. —4, ventral or peripheral aspect of the base of the body-chamber (nat. size), showing at m, m, marks of the shell-muscles (m in all the other figures has the same meaning) ; y, in all the figures (exclusive of ¢) refers to the pitted and rugose surface of the muscular impressions: B, dorsal (internal) aspect of the same fragment, ¢, test, 27, dorsal lobe of a septum: C, base of the body-chamber of a larger (? adult) specimen, ¢, test, gr, groove: D, reduced figure of a nearly perfect example of this species, from which the fragment lettered 4 and B was removed, as explained elsewhere in the text: , outline, much reduced in size, drawn from a cast of the interior of Nautilus pompilius ; t, finely impressed lines left by the shell-muscle, s, sutures of the septa. was used by Hackel for a genus of Radiolarians. The name Trematoceras proposed by Hyatt (Proc. Boston Soc. Nat. Hist. 1883, vol. xxii. footnote, p. 291) in lieu of Trematodiscus is equally ineligible, because preoccupied, for although the species described by Hichwald (Leth. Rossica, 1860, vol. i. p. 1259)—Trematoceras discors —was a Bactrites, a generic name once published cannot be again employed, even for a different group, without risk of confusion. 496 MM. Foord & Crick—Shell-muscles of Celonautilus, ete. A drawing has also been made (Fig. EH), much reduced in size, from a cast of the interior of the shell of Nautilus pompiiius, in order that the muscular impressions of C. cariniferus might be compared with those of existing species. Fig. D represents the specimen selected for illustration, it is reduced in size from the original about one-half. The portion marked with the letters p, m, was removed from the rest of the shell in order that the muscular impressions might be drawn as seen in Figs. A and B, which are of the actual size. Fig. C is taken from a larger (probably adult) specimen of C. cariniferus (‘Sowerby Collection,’ No. 43861), and shows the marks of the shell-muscle on one of the angles of the whorl more distinctly than they can be seen on the smaller one. We will now describe these figures more in detail. Figure A represents the ventral or peripheral side of the base of the body- chamber. The impressions of part of the shell-muscles are seen at m, m, while p indicates their rugose and pitted surface, and proves how strongly they were attached at the angles of the whorls; this is further evidenced by the deep groove gr. in Figure C. Connecting the broader portions of the muscular impressions is a narrow band, near the centre of which there is a little shallow pit (see Figure A), which undoubtedly formed part of the muscular system, as the narrow band is slightly enlarged at this point to embrace it.’ Figure B is the under side of A. On this side it will be seen that the narrow band at its central part is strongly deflected backwards, in a similar manner to that of the annulus of the recent Nautilus (N. pompilius), so well figured (pl. xxxix. fig. 4) by Dr. W. Waagen in his well-known memoir entitled ‘Ueber die Ansatzstelle der Haftmuskeln beim Nautilus und den Ammoniden.” * The deflected portion bears several shallow, more or less elongated pits (see Figure 8), which seem to indicate a rather strong attach- ment of the muscles at this point, though not so strong as at the angles of the whorls, where the muscular impressions are broadest. Figure C represents the base of the body-chamber of a larger specimen than that from which 4 and B were drawn, and is designed to show more distinctly the pitted and rugose surface of the cast, proving, as already remarked, the strong attachment of the muscles at the angles of the whorl. Part of the test (¢) has been removed in order to expose this part of the muscular impression more com- pletely. On examining the interior of the body-chamber of the shell of the recent Nautilus (either N. pompilius or N. umbilicatus) two somewhat inconspicuous lines (Fig. /, m) are observed, enclosing a space which on the dorsal and ventral sides of the shell forms a narrow band,—the impression of the annulus,—but expands at each side into an irregularly oval space,—the impression of the shell-muscle,—of which the outer boundary is strongly arched forwards. Corresponding in direction 1 This enlargement is not indicated in the Figure, as it should have been. 2 Paleontographica, bd, xvii. 1870, p. 185, plates xxxix. xl. MM. Foord & Orick—Shell-muscles of Ceelonautilus, ete. 497 with the line forming the outer boundary, and covering the whole of the space between this and the last-formed septum, are a series of very fine impressed lines (marked J in Fig. Z). These lines indicate successive points of attachment of the upper edge of the shell- muscle, representing a gradual forward movement, little by little, of the animal in its shell during growth. It should be observed that the line constituting the lower boundary of the muscular impression is only seen where the muscle was last attached. That the organic attachment of the shell-muscles of the recent Nautilus to the shell was very slight (thus contrasting strongly with Celonautilus) has been pointed out by J. D. Macdonald? and subsequent writers.? Macdonald’s description is so important and interesting in this connection that we quote it 7m extenso :— “With reference to the action of the great lateral muscles of Nautilus, the following ideas have suggested themselves to my mind, “As though preparatory to the complete separation of the body of the Cephalopod from the shell, which is usually present in the lower genera, the fasciculi composing the lateral muscles in Nautilus do not perforate the mantle, and therefore cannot be directly fixed into the shell; they are, however, connected with it through the medium of thin filmy layers of a corneous texture, which frequently remain attached to the shell after the animal has been removed. The feeble hold of those muscles, even in a very recent state, is thus readily accounted for. Indeed, it is highly probable that the fixity of the body of Nautilus during the inhalation and forcible ejection of the respiratory currents is effected by the shell-muscles reacting upon one another, on the principle of a spring purchase, rather than by simple traction, as illustrated by the withdrawal of a Gasteropod within its retreat, or the closure of a conchifer by the adductor muscles. “This view, which is supported by the foregoing facts, has its principal basis in the line of direction of the shell-muscles, and the angle at which they meet one another, at the root of the funnel- lobe; for, the outer extremity of each being fixed, it follows that the first effect of the contraction of the muscular fibres would be to increase the angle just noticed; and this cannot possibly be accom- plished, according to the recognized laws of muscular action, with- out tending to throw apart the points of origin, or, in other words, exerting outward pressure against the internal wall of the shell, and thus, as it were, jamming the occupant tightly in its cell.” In order that the above description may be more readily compre- hended we here append a reduced copy of the figure given by Sir Richard Owen in his ‘“ Memoir on the Pearly Nautilus,’ 1832, plate 3, fig. 2. A comparison of the muscular impressions of Cclonautilus with those of the recent Nautilus points to the conclusion that the animal 1 Proc. Roy. Soc. 1856-7, vol. viii. p. 381. * Prof. Blake, ‘‘ Brit. Foss. Ceph.” pt. i. p. 10; see also ‘‘ Note on the Pearly Nautilus,’ by E. A. Smith, F.Z.S.. m ‘‘ Journ. of Conchology ” for Oct. 1887 ; also ‘ Catalogue Fossil Cephalopoda,’ British Museum (Nat. Hist.), pt. i. 1888, p. xi. DECADE I1I.— VOL. VI.—wNO. XI, 32 498 MM. Chapman & Sherborn—Foraminifera of the London-clay. must in the former have been fixed more firmly in its shell than in the latter, and that in all probability the shell-muscles were not limited to the sides of the animal, as in the recent JVautilus, but completely encircled it. The difference between the shell-muscles of Celonautilus and those of the recent Nautilus strongly supports the view that the two forms are generically distinct, a conclusion already arrived at from the great dissimilarity in the form of their shells by such an eminent authority as Prof. Hyatt. The subdivision of Nautilus was, in fact, begun long ago by M‘Coy? and continued by Meek,? the latter of whom expressed his decided opinion that such divisions should at least rank as distinct subgenera. Under surface of the head of Nautilus pompilius, with the mantle divided and the funnel turned back to expose its cavity and the shell-muscles. a. a. The divided portions of the mantle; 4. 6. Sheaths of the tentacles ; ¢. ¢. The funnel; d. Its valve; e. e. Shell-muscles; jf. f. Their terminations or surfaces of attachment; g. The transverse fibres connecting them. VIJ.—ForaMInIFERA FROM THE Lonpon Cxay oF SHEPPEY. By Freprrick CuapmMan and C. Davies SHERBORN. N the Proceedings of the Geologists’ Association for 1878,* Mr. W. H. Shrubsole, F.G.S., published a list of Foraminifera obtained from the London Clay of Sheppey. The following list, the result of an examiuation of some material courteously lent to us by Professor J. W. Judd, F.R.S., adds considerably to the fauna of Sheppey and includes two species not previously recorded from the London Clay. Forty-one forms have been determined, of which twenty-six* are new to Sheppey, thus bringing up the number of forms recorded from that locality to eighty-six. The geographical distribution of the Foraminifera of the London Clay was fully tabulated in 1886,° 1 Synopsis of the Carboniferous Limestone Fossils of Ireland, 1844. * United States Geol. Survey of the Territories, 1876, vol. ix. p. 490. 5 Proc. Geol. Assoc. vol. v. no. 7, p. 355, 1878. 4 Numbers 4~9, 11, 13-15, 19-23, 26-30, 38, 386-41, of the list appended. ® Sherborn and Chapman, Journ. R. Microsc. Soc, [2], vi. 1886, p. 759; and ibid. 1889, p. 483. A. Smith Woodward—The Devonian Ganoid Onychodus. 499 and it is interesting to find so many of the forms there figured and recorded for the first time from the London area common to both localities. The figure following the specific name in the list appended shows the relative abundance of the varieties found. The two forms deserving mention as new to the London Clay are: Pleurostomella alternans, Schwager, Novara Reise, 1866, p. 288, pl. vi. figs. 79 and 80; H. B. Brady, Rep. “Challenger,” 1884, p- 412, pl. li. figs. 22 and 23; Pleurostomella eocena, Gtimbel, Abh. k.-bay. Ak. Wiss. vol. x. 1868, p. 680, pl. i. fig. 53. A single small specimen, slightly broken on one side, but preserving all the charac- teristics of the genus. Lagena desmophora, Rymer Jones. L. vulgaris, var. desmophora, Rymer Jones, Trans. Linn. Soc. vol. xxx. 1872, p. 54, pl. xix. - figs. 23, 24; L. desmophora, H. B. Brady, Rep. “Challenger,” 1884, p- 468, pl. lviii. figs. 42 and 48. Characterized by prominent decorated costee, the intercostal areas being occupied by one or more cost, less prominent and unornamented. One specimen precisely corresponding to figure 42 in Brady’s report cited above. Four species of Ostracoda were found, of which two are apparently new. The following is a list of the Foraminifera :— 1. Miliolina trigonula, Lam. sp. 6. 23. Dentalina acicula, Lam. sp. 2. 2. Ammodiscus incertus, d’ Orb. sp. 3. 24. Marginulina Wethereliii, Jones, 27. 3. Textularia agglutinans, d Orb. 18. 25. Cristellaria italica, Detr. sp. 1. 4. Bigenerina capreolus, d Orb. sp. 14. | 26. —vy.spinuloxa,Sherb &Chap.1. 5. Gaudryina pupoides, d’Orb. 10. 27. cultrata, Montf. sp. 18. 6. Clavulina communis, d’Orb., 7. 28. Polymorphina gibba, d Orb. 1. 7. parisiensis, d’ Orb. 2. 29. gutta, d’Orb. 1. 8. Bulimina afinis, @Orb, 2. 30. Urigerina asperula, Oziz. 6. 9. Pleurostomella alternans, Schw. 1. 31. Globigerina bulloides, d’Orb. 4. 10. Lagena globosa, Mont. sp. 1. 32. Orbulina unwersa, d’ Orb. 1. 11. desmophora, Ry. Jones, 1. 33. Pullenia quinqueloba, Reuss, 3. 12. marginata, Walk. & Boys, 1. 34. Discorbina rosacea, d’Orb. sp. 1. 13. Nodosaria radicula, Linn. sp. 3. 35. Planorbulinaammonoides, Reuss, sp. 1 14. humilis, Roem. 9. 36. complanata, Reuss, sp. 6. 15 longiscata, d’ Orb. 16. 37. Anomalinagrosserugosa, Gumb.sp.4. 16. soluta, Reuss, 4. 38. Pulvinulina repanda, Ficht. & Moll, 17. -— raphanus, Linn. sp. 1. sp. 2. 18. badenensis, W’ Orb. 2. 39. —— var. concamerata, Will. 3. 19. polygona, Reuss, 5. 40. —— Karsteni, Reuss. 1. 20. Dentalina communis, d’ Orb. 5. 4}, punctatula, d’Orb, sp. 17. 21 consobrina, a’ Orb. 12. 42, —— striato-punctata, Ficht. & Moll, 22 spinulosa, Mont. sp. 10. sp. l. VIII.—On ror Occurrence or THE Devontan GanoIp OnYcHobvus IN SPITZBERGEN.! By A. Smira Woopwarp, F,G.S., F.Z.S. URING a visit to Stockholm last spring, Prof. Gustav Lindstrom kindly permitted the writer to examine the series of remains of Paleozoic fishes obtained from the Devonian of Spitzbergen by Dr. A. G. Nathorst, during the Swedish Geological Expedition in 1882. Some of the more prominent specimens have already been briefly noticed, with figures, by Prof. Ray Lankester;* but the 1 Read before Section C (Geology), British Association, Newcastle, 1889. * KE. Ray Lankester, ‘‘ Report on Fragments of Fossil Fishes from the Paleozoic Strata of Spitzbergen,”’ Kongl. Svenska Vetensk,-Akad. Handl., vol. xx. (1884), No. 9, pp. 1-6, pls. i.-iv. 500 Notices of Memoirs—W. H. Hudleston— collection is worthy of a more detailed comparative study than that to which it has hitherto been subjected, and among the undescribed specimens most readily identified is a small fossil indistinguishable from the so-called ‘‘intermandibular arch” or ‘ presymphysial bone” of Onychodus.1 Through the kindness of Prof. Lindstrom, this specimen has been forwarded to the British Museum for examination, and it forms the subject of the following remarks. Four fractured teeth are exhibited, attached in close series to a narrow arched base, and the fossil is firmly imbedded in a hard matrix. It is evidently imperfect, but the base preserved is 0-005 in length, and the uppermost and longest tooth has a nearly similar measurement. This tooth is slender, tapering, and gently curved, without any sigmoidal twist; and both it and the more imperfect teeth below are characterized by the relatively enormous size of the internal cavity. In its small dimensions the presymphysial dentition from Spitz- bergen most nearly approaches that of Onychodus anglicus,” from the Lower Old Red Sandstone Passage Beds of Ledbury, Herefordshire ; but it is distinguished by the more uniformly tapering character of the teeth, and the relatively larger size of the pulp-cavities. In the latter feature it seems to be more nearly paralleled by the much larger, typical species from the Devonian of the United States; but all described forms differ from the new fossil in the larger size of the teeth in proportion to their base of attachment. The Spitzbergen species, thus imperfectly indicated, may therefore be regarded as hitherto unknown, and, in reference to its interest from a distri- butional point of view, may be named Onychodus arcticus. INT CMRAKe AS). (Say AMeAIMFON LIES) - Tur Grotocy or Devon, Facts anp INFERENCES, FROM THE PRESIDENTIAL ADDRESS TO THE DEVONSHIRE AssocraTion. By W. H. Hupuzston, Esq., F.R.S., Sec.G.8., ete. August, 1889. E scan have little doubt that this South-western part of England had the honour of leading off the Geological Surveys of the world because of its great metallic wealth, and because of the interesting and complicated phenomena associated therewith. But it must not be supposed that the early Surveyors settled every question fifty years ago, especially when we bear in mind the varied nature of the region, the obscurity of many of the problems, and the comparative novelty of the task. Devonshire especially has been the theatre of many a geological battle since then, nor can we aver that the temple of Janus is at present closed. It is twenty-one years ago, I believe, since a President of the Devon- shire Association dealt with any of these topics from the chair. Mr. Pengelly, in the year 1868, after giving an admirable summary of 1 J. S. Newberry, Geol. Survey of Ohio, vol. i. pt. ii, (Paleontology), pp. 296-302, pts. XXvi. XXVil. ® Smith Woodward, ‘‘ Note on the Occurrence of a Species of Onychodus in the Passage Beds of Ledbury,’’? Groz, Mac. Dec. III. Vol. V. (1888), p. 500. Presidential Address—The Geology of Devon. 501 the progress of geology in Devonshire up to that date, propounded nine questions for special consideration in the future. These I venture to recall to your memory— The age of the crystalline schists of the Bolt. The precise chronology of our Limestones and associated rocks. . Is there east of Exmouth a break in the Red rocks ? Whence come the Budleigh Salterton pebbles? . Whence also the porphyritic trap nodules so abundant in the Trias ? . Are our Greensands really of the age of the Gault ? . Whence the flints so numerous in our existing beaches ? . What is the history of our superficial gravels, and are there any indications of glaciation in Devonshire ? 9. To what race did the Cave-men belong ? During the interval of over twenty years most of these questions have been discussed, often by Mr. Pengelly himself, and the records are to be found in the volumes of your Transactions. Confining any remarks I may have to make on the present occasion to points bearing on the physical history of the county, I would say that these questions may be grouped under five heads—(l.) Recent and Pleistocene geology; (2.) The extent and nature of the Cretaceous rocks; (3.) The New Red question; (4.) The Old Red question ; and lastly (5.) The age of the crystalline schists, to which may be appended any necessary remarks on petrological questions. DAD NPwde RECENT AND PLEISTOCENE GEOLOGY. The recent geology of the county is famous, as all the world knows, for the occurrence of raised beaches, submerged forests, and bone caves. On these I scarcely venture to touch, the cave-question especially verging on the confines of archeology. If the caverns at Oreston were first made the subject of scientific enquiry, those of Kent’s Hole and Brixham have yielded results of surpassing interest. Going a step further back in time, there are few problems more obscure than the history of the plateaux gravels of the southern counties : these consist largely of flint. Mr. Parfitt, speaking of the drift gravels towards Dawlish, has expressed his opinion that the agents producing these were ice and water. To this we can scarcely demur, but it was hardly necessary to have included Devonshire in the ice-sheet. The indications of glaciation in this county are matters of inference rather than self-assertion, and observers, like Mr. Somervail, accustomed to the marked features of a thoroughly glaciated country, are slow at finding any evidence of it here. Still it must be obvious to all who reflect upon the subject that the cold which has left such enduring evidences of its intensity in areas so near, for instance, as Caernarvonshire, must have affected the Devonshire climate to a considerable extent. The absence of true Boulder-clay should reconcile the Devonian to the fact that his country is destitute of cowslips, which are very partial to the Boulder-clay soils of the North of England, and are far from scarce in the heavily-bouldered regions of Hast Anglia. It is true that the 502 _ Notices of Memoirs—W. H. Hudleston— Swedish botanist Nathorst, speaking of the peculiar mixture of clay and stones known as the “‘ Head’ of Bovey Tracey,” called it Boulder-clay; and Mr. Pengelly likewise mentioned lately that another Scandinavian authority, Dr. Torell, when in company with ~ Mr. Ormerod as long ago as 1868, professed to have detected three moraines on Dartmoor in the neighbourhood of Chagford. That these were the results of an ice-cap, as that term is generally under- stood, I do not regard as probable; but bearing in mind the recorded facts, and also the frequency of such features as ‘“‘ terminal curvature,” we may well believe with Mr. Worth in the existence of something like a local snow-cap on the higher grounds. The peculiar nature of the cave-breccia, and the Arctic character of some of the cave- animals, also point in the direction of a colder climate. Not that this evidence is really required, except as a matter of corroboration. We may believe, then, in a glaciation so modified that its results require close search before they can be appreciated. Tse Extent anp Nature oF THE OretTAcEous Rooks. There are few problems in the physical history of the South-west of more interest than this. Speaking of the geology of the neigh- bourhood of Dawlish, Mr. Ussher says there can be little doubt that the Cretaceous highlands of Devon, such as the Haldons, are portions of a great plain of marine denudation, and he speaks of a time when that Cretaceous tableland abutted on the flanks of Dartmoor. He also refers to the presence of flints in the old and more modern gravels as evidence of the extension of Chalk débris. It is interest- ing to know that abundant fossil evidence of the former existence of Middle Chalk (the Upper Chalk of some writers) is found in the chert and flint beds which form the capping of Little Haldon; the Hchinodermata are especially characteristic. Mr. Ogilvie Hvans has called attention to this fact. As regards the former extension of the Chalk, I see no reason to doubt that the western part of what is now the Channel and the greater portion of Devonshire and Cornwall were submerged beneath the Chalk Sea. It seems to me that in no other way can you account for the quantity of flints on the western beaches and in the bottom of the Channel. But, irrespective of this corroborative evidence, one would expect the Chalk Sea to have extended in this direction. Then comes the question, Was there any western limit to the Chalk Sea, or did its waters mingle freely with the Atlantic Ocean during the period of extreme depression? At the epoch when the Upper Greensand, or basal sediment of the Chalk, was being laid down, Mr. Jukes-Browne, in his “Building of the British Isles,” represents the extreme western shore-line, plotted on the existing map of Devon as passing from the Ermemouth towards the Haldons; @.e. roughly parallel to the E.S.H. flank of Dartmoor. Now the distance from the Ermemouth to the present edge of the deep Atlantic basin is about two hundred miles, and that two hundred miles would represent the width of the land which intervened between the Upper Greensand Sea and the Atlantic Ocean at the Presidential Address—The Geology of Devon. 503 particular period indicated in the hypothetical map to which I have referred. It is a question for separate consideration whether that intervening space of land was wholly or only partially submerged at a later epoch during the period of extreme depression. For our purpose it will be sufficient to have carried the western margin of the Chalk Sea beyond the limits of the Cornish peninsula during the period of lowest depression, and this I think we may fairly claim. I ought to observe that it is not assumed that the Hnglish Channel had any existence at that time. Mr. Jukes-Browne regards the Channel as a very modern feature in physical geography, but the existence or non-existence of the Channel as a mere excavation will hardly affect the question of the westward boundary-line of the Chalk Sea. One more question of Mr. Pengelly with reference to Cretaceous geology remains, viz. the age of the Devonshire Greensand. It was Fitton, and after him Meyer, who maintained that the Black- down Beds were of Lower Cretaceous age, although before their time De la Beche had classified them as Upper Greensand, whilst Godwin-Austen described them as possibly a sandy condition of the Gault. The littoral facies and abundance of Trigonie, having considerable resemblance to Lower Greensand species, led Mr. MeYer astray. Dr. Barrois and other authors entered the lists, and when Mr. Downes read his excellent paper before the Geological Society in 1881, the balance of opinion tended to the view that the Gault, or most of it, is represented in the Blackdown Beds, and that seemed also to have been Mr. Downes’ opinion. If the Ammonites in that gentleman’s collection have been correctly determined, there would seem to be a mixture of Lower-Gault with Upper-Gault | forms; but as the Upper-Gault of the Hast of England is represented to a considerable extent in the West by the Upper Greensand, it follows that, if we allow most of the Gault to be represented in the Blackdown Beds, such a determination carries the Upper Greensand with it, so that both De la Beche and Godwin-Austen were right. There is not a trace of Lower Greensand, and when we bear in mind that the Lower Greensand has already disappeared to the eastward, its revival at Blackdown would be an anomaly. But a further argument in this direction, which Mr. Downes, aided by Mr. Vicary, was the first to indicate, is derived from the fact that the nine lowest horizons indentified at Blackdown are missing at Haldon. This proves conclusively that the basal rocks of the Upper Cretaceous ever occupy a higher horizon as we proceed westwards, and, as we have already seen, this has an important bearing on the question of the final westward limit of the Chalk Sea. It is quite possible also that the missing beds of Chalk were more siliceous than their equivalents further eastwardly, and this would still further help to account for the flints so numerous in the Channel and adjacent shores. There are two points in connection with Blackdown which might be mentioned: 1st, Mr. Downes read a paper before the Geological Society in November, 1884, ‘On the Cretaceous Beds of Black 504 Notices of Memoirs—W. H. Hudleston— Venn, with some supplementary remarks on the Blackdown Beds.” There he appeared to arrive at the conclusion that the Lima- parallela-bed of Black Venn is lower than the lowest of the Blackdown Beds, for it thins out before reaching Sidmouth. He again notices the general thinning out westwards. ‘These latter conclusions are somewhat at variance with his previous ideas that the Blackdown Beds represent the whole of the Gault, and he finally inclined to the opinion that the Blackdown Beds were Upper Green- sand rather than Gault. I have before pointed out that the Upper Greensand partly represents the Upper Gault of the south-east of England, and this interpretation will help to explain the apparent contradiction. 2nd. The mode in which the clumps of Zurritella and Pectunculus occur in the Blackdown Beds reminds me of the similar way in which their modern representatives occur in the English Channel. Not far from Hope’s Nose is a muddy bed full of Turritella, showing how the shell is apt to accumulate from some cause or other in one or two particular spots, and throughout the Channel it is by no means uncommon to come across Pectunculus in great numbers at particular spots. New-Rep Beps. The New-Red question next demands our attention, since the Jurassic rocks of Devonshire are limited to a very narrow strip of Lias in one corner of the county. The phenomena in connection with the New-Red beds are of great interest in spite of their poverty in organic remains. We are as much interested in the composition of these beds as in ascertaining their precise chronological value. Thus two of Mr. Pengelly’s questions relate to the composition of _ Triassic pebble-beds. It would certainly appear from Mr. Davidson's determination of the Brachiopoda that a considerable portion of the Budleigh-Salterton pebbles were of Devonian origin or aspect, although there are a sufficient number of admitted or possible Silurian species. Thus Salter’s original proposition that they are Normandy types of the May-Hill Sandstone may in part be correct, the fossils being characteristic of beds on both sides of the Channel. The rocks from which such pebbles were derived are certain to be no longer in existence; the pebbles themselves are mere survivals of an ancient denudation, just as is the case with the flint pebbles whose origin we have lately been considering. It is not difficult to believe that both Silurian and Devonian beds were largely developed in portions of what is now the Channel area. Indeed the form of the present peninsula of Normandy clearly points in that direction, whilst projections of Paleeozoic rock from what is now the Devon- Cornwall peninsula may likewise have contributed their share. Hence an extension of the Gorran Haven beds, or of La Manche, points almost equidistant, may have been amongst the missing rocks from whose hardest parts some of these pebbles were long ago torn. There is no evidence, so far as I am aware, that the English Channel, in anything like its present form, had any existence in Mesozoic times, and we may well believe this without going so far as Mr, Presidential Address—The Geology of Devon. 505 Jukes-Browne, who represents the English Channel as merely a feature of Pleistocene geography. Doubtless the origin of the English Channel is a problem well worthy the attention of Devon- shire geologists, but at present we are considering the composition of Triassic pebble-beds, and must not, therefore, allow ourselves to be led off on a false scent. Mr. Pengelly’s other question, as to the origin of the porphyritic trap nodules, is one which embraces a far wider scope; for along with it must be considered the subject of igneous fragments in ‘the New-Red generally. One would be disposed to say that most of them were derived from the felspathic traps, so many of which make their appearance at the junction of the Carboniferous and New-Red. This peculiarity of position Mr. Vicary was disposed to attribute to the circumstance that these traps have served to arrest denudation in the Trias. It is said that none are to be seen in the coast section. Mr. Vicary regarded the earliest eruptions of this class of rock as having taken place between the close of the Carboniferous and the commencement of the Triassic, whilst the latest outbursts were of Triassic age. Mr. Downes also, whilst endeavouring to account for the presence of some Upper Devonian fossils in the Trias near Tiverton, has expressed his opinion that the hypothesis of an active volcano upon the coast of the early Triassic sea best meets the requirements of the case. Mr. Somervail likewise has expressed his views on the probable volcanic origin of the breccias at the base of the Trias in South Devon, and as to the conditions prevailing during their accumulation. It cannot be doubted that a careful and unprejudiced study of the igneous rocks in the Devonshire Trias will help to throw much light on an important stage in the physical history of the area. But in undertaking such an investigation due allowance must be made for the changes which the fragments have themselves undergone in a highly permeable formation. If lumps of hard limestone, under the influence of siliceous infiltration, have been converted into that peculiar form of orbicular silica known as “ Beekite,”’ we need not be surprised at felspars, derived originally from Dartmoor, having been converted into Murchisonite, which chemically differs from orthoclase mainly in containing somewhat more alumina. And thus it came to pass that pieces of Dartmoor granite were unrecognizable, whilst a generation of geologists, following De la Beche and Godwin-Austen, were disposed to believe that during the New-Red epoch, the granite of Dartmoor had not as yet reached the surface. Lately, speculation has taken quite a different turn. Mr. Worth is disposed to think that the granite of Dartmoor passed upwards into felsitic and volcanic rocks, remnants of which, he says, are to be found in the Triassic conglomerates of the county. Geologists, therefore, having started with the belief that the Dartmoor granite was covered up by sedimentaries in Triassic and pre-Triassic times, are now presented with a picture of a pre-Triassic volcano towering into the skies. It is also intimated that andesites and specimens of volcanic grit such as arise from the denudation of volcanic cones have been found in much more recent deposits. 506 . Notices of Memoirs—W. H. Hudleston— Confining our attention for the present to the New-Red rocks, one would suppose that if the above speculations have a good foundation, the evidences of volcanic rocks derived from the disintegration of the old Dartmoor volcano ought to have been much more abundant in the Triassic conglomerates than they have hitherto seemed to be. But the further investigation of this matter must be deferred until we have considered the chronology of the New-Red beds. We now perceive the import of the question put by our pro- pounder of riddles, “Is there east of Exmouth a break in the ‘red rocks’?” So recently as 1881 Mr. Pengelly wrote: “I incline to the opinion that our Red Rocks, taken as a whole, belong to the Keuper; or, if not, that all three sub-systems of the Trias are represented in Devon.” Of course, when Mr. Pengelly thus infers the existence of the middle member of the Trias, he can only mean that the Muschelkalk is represented in time. Mr. Ussher, four years previously, had given in the Transactions of the Association the results of his experience in the classification of the Triassic rocks. His view was that whilst in the Midlands there is complete unconformity between the Bunter and Keuper, in Devonshire the Triassic beds present a conformable series. He also showed that the beds cut out at Straight Point and Exmouth, in the south-coast section, are visible in the inland districts, thus practi- cally answering Mr. Pengelly’s question in the negative. The once prevalent notion, therefore, that the whole of the Devonshire Trias is of Keuper age, a notion which seemed to have the support of high authority, must be abandoned. A series of marls and sandstones, called by Mr. Ussher ‘“ Middle Trias,” he thought might roughly represent the Muschelkalk in time, whilst his ‘Lower Trias,” consisting of sandstones and breccias with igneous fragments, so well developed between Dawlish and Watcombe, is mainly of Bunter age. ‘The older beds would presumably occur to the westward, but there does not seem at this time to have been a suspicion of Permian on the part either of Mr. Ussher or Mr. Pengelly. Mr. Ormerod, in his notes on the deep borings in the Trias at Teignmouth, also describes the beds between the Exe and the neighbourhood of Torquay as belonging to the Bunter. In a communication to the Geological Society Mr. Ussher speaks of the lowermost beds of the south-coast Trias as far exceeding their more northerly equivalents in thickness, and as affording a strong probability that a reconstruction of the English Channel valley would exhibit a still greater development of beds, dating as far back perhaps as late Permian times. It is thus evident that Mr. Ussher considers that a large extent of New-Red rock has been destroyed in the formation of the English Channel, and possibly portions may yet be ‘proved in the bed of the Channel itself. Mr. Worth, as you know, considers that he has evidence of the existence of Triassic rocks in siti fifty miles to the south-west of the Triassic outlier at Cawsand, in Plymouth Sound, but it is rather a peculiar feature in this case, that the supposed submarine Trias resembles the Keuperian or eastern variety of the Devonshire Red Rocks. Mi. Presidential Address—The Geology of Devon. 507 Irving, who has paid some attention to these questions, differs from Mr. Ussher, and still more from Mr. Pengelly, in the belief that the breccia series is of Permian age. He regards it, in fact, as the result of terrestrial and littoral deposits on the flanks and on the shore- line of the old mountain region of which the Devon-Cornwall peninsula is one of the remnants, the high inclination of the dip being in favour of its being mainly composed of mountain detritus. It would be difficult indeed to assign any other origin to the wonderful group of beds which constitute the sea-cliff between Teignmouth and Dawlish. The only matter in dispute is the precise chronology of these beds. Shall we say with Mr. Pengelly that they are of Keuper age? or with Mr. Ussher and Mr. Ormerod, that they are of Bunter age? or shall we agree with Mr. Irving that they are of Permian age? In the absence of marine mollusca the precise age of any series of beds is difficult to determine; all that we can affirm with absolute certainty is that they belong to the Permio-Triassic interval, and that in this country such beds are more usually Permian than Triassic. The brecciated beds of the Leicestershire Permians, for instance, have been recently shown to be composed of the re-arranged talus of the harder portions of the Palzeozoic rocks surrounding that part of the old Permian lake. Tur Post-CarsonireRous INTERVAL. Leaving the question of the actual chronology of the Dawlish beds as almost hopeless in our present state of knowledge, we must be content to bear in mind the main facts of the case, viz. that towards the close of the Carboniferous period one of those great shifts in the earth’s crust occurred, of which there have been three or four during geological time. Roughly speaking the Paleozoic epoch terminated with this great movement, whose flexing action has, in the main, governed the axes of the series of synclinals and anticlinals existing between the Bristol and English Channels, with an extension towards the south so as to include the peninsula of Brittany. The principal of these earth-throes occurred during the unrepresented period of time which intervened between the Coal- measures, as usually developed, and the Permian; and though there are evidences of subsequent oscillation in our district to a moderate extent, no instances of folding and contortion occur in the beds deposited afterwards. Then it was that the building of the British Isles commenced in earnest, and that the first rude sculpturings of the future Devonshire were made. Some of these points we shall have to consider again in reference to the general structure of the county. Tur CaRBONIFEROUS. Before proceeding to answer the remainder of Mr. Pengelly’s questions, a few words may be devoted to a formation which in Devonshire is both extensive and disappointing. No attempt will be made to correlate any portions of these beds wih their pre- sumed equivalents on the Welsh side. All we can say is, that 508 Notices of Memoirs—W. H. Hudleston— | the Old-Red of the Welsh border does not differ from the Devonian of Devonshire more than does the Carboniferous of Wales from beds of the same system in this county. The Culm-measures are something sui generis, and it seems difficult to account for their origin. It may be worth mentioning in this connection that Dr. Barrois, speaking of the physical history of Brittany, which presents certain analogies with that of our south-western peninsula, observes that the Carboniferous period in that region was one of oscillation between terrestrial and marine conditions—a period of extensive eruptions and great earth movements. Hence he says that a considerable portion of the sediments, especially towards the base, are of volcanic origin. This is not at all the case with the Carboniferous in North Devon, where the sequence is undisturbed. According to the views generally accepted, the main horizon for contemporaneous igneous rocks in the Paleozoic of Devonshire lies in the Lower Devonian, though there seems to be some difference of opinion upon this point, THe OLD-RED oR DEVONIAN QUESTION. This may with justice be termed the home question ; but in order to attempt a solution, it will be found necessary, in the first instance, to take into consideration the Old-Red Sandstone of other areas. The claim of the Devonian to recognition as one of the great geological systems has been challenged more than once; and even when this has not been disputed, there have been divers contradictory efforts to fit in the marine Devonians with the several members of the Old-Red Sandstone. In North Devon the matter was further complicated by the great Jukesian heresy, based on the alternative supposition of a concealed anticlinal with an inversion towards the north, or more probably an east and west fault. These ideas, as you know, were successfully combated by Mr. Etheridge and Mr. Townshend Hall in the earliest days of the Association; and about ten years ago the latter gentleman reviewed the history and classifi- cation of the North-Devon Rocks in an able paper which appeared in the “Transactions.” His own classification of the North-Devon beds differs in details from that adopted by Ussher and Woodward ; but this is a matter of minor importance, since all agree in regarding the Ilfracombe limestones and associated slates as a definite central datum line, from whence to proceed either above or below. Mr. Hall observes that the North-Devon beds from Lynton to Pilton, though preserving a general dip to the south, are folded into many anticlinals, reducing their apparent thickness very considerably. Having got the North-Devon beds, which are really the key to the whole Devonian system, into something like order, it now becomes necessary to quit the county for a while in order to study the Old-Red Sandstone on the other side of the Bristol Channel. And here we realize the fact that there are two Old-Red Sandstones, the Lower of which is perfectly conformable with and passes down into the underlying Silurian, whilst the Upper passes conformably into the Carboniferous, of which system, in a certain sense, it may Presidential Address—The Geology of Devon. 509 be regarded as the base. It is only in recent years that this uncon- formity between the Lower and Upper Old-Red Sandstone has been fully recognized. Moreover, this is by no means a local phenomenon confined to the Welsh districts, since in the South of Ireland there is a great hiatus between the presumed equivalents of the Pickwell Down beds above and those of the Lynton beds below. Thus both in the South of Ireland and in South Wales the time representatives of the Ilfracombe and associated beds are absent. These three districts are more or less involved in the great post-Carboniferous east-and-west folding, and may be said to belong to the same system of physical disturbance. But even in Scotland Hugh Miller’s Old-Red Sandstone is found to consist of two ‘portions, the lower part shading off into Silurian, the upper into the Carboniferous. Thus, throughout the British Isles, what was formerly known as the Old-Red Sandstone is found to consist of two very distinct members, widely separated from each other in point of time, each having affinities with the neighbouring system. If, then, the case rested on the Old-Red Sandstone alone, its fate would only differ from that of Poland in being partitioned between two instead of three ambitious neighbours. Having learnt thus much with regard to the Old-Red Sandstone, it is now time to return to North Devon, where we have a fossiliferous series interposed between beds which are held to be the equivalents, mutatis mutandis, of the Lower and Upper Old-Red Sandstone re- spectively. It is these fossiliferous beds which forge the link that was missing, whilst the intermediate yet independent character of their fauna justify, on paleontological grounds, their being regarded as the head-quarters of a distinct and separate system. The more copious development of the remains of marine organisms in the corresponding beds of South Devon further justify the original determinations of Lonsdale. It is these central beds, therefore, which constitute the backbone of the Devonian system; and if the correlations to which I have alluded be substantiated, they must carry with them the Upper and Lower Old-Red Sandstone as integral parts of that system. It seems to be generally admitted that the Pickwell-Down beds are really the equivalents of the Upper Old-Red Sandstone. Perhaps it was Professor Hull who first suggested this, but nearly ten years ago Mr. Champernowne, whilst agreeing that the Pilton and Marwood beds should be referred to the Carboniferous, considered the Pickwell-Down Sandstone to be true Old-Red Sandstone, and also Upper Devonian. The fact of the Pickwell-Down beds being unfossiliferous lends additional probability to this view. The correlation of the lowest Devonian beds with the Lower Old-Red Sandstone seems more open to discussion. In the first place the subject is complicated by the suggestion that the Foreland and Hangman Grits are repetitions of the same beds by means of faulting, and secondly the arenaceous beds of the Lower Devonian in North Devon yield some marine mollusca. The resemblance of the Foreland Sandstones to the Glengariff Grits was regarded by 510 Notices of Memoirs—W. H. Hudleston— Professor Hull as most striking. On the whole there still seems a little obscurity as to the details of the lowest Devonian beds on the Bristol Channel. There would be no use in considering the Tevouiae sequence in South Devon until that in North Devon had been fairly settled. It is not always that opportunities are afforded for studying a set of beds in duplicate within a limited distance, but I have had occasion to notice, more than once, the very great differences of development that present themselves under such circumstances within areas not so very far apart. Doubtless the original differences were very considerable, since South Devon must be regarded to a certain extent as a reef region, and the beds moreover were largely reinforced by contemporaneous volcanic matter of a basic nature, from which the equivalent beds in the North Devon area were almost entirely free. But in addition to these congenital elements of difference are others belonging to a subsequent period, such as a further extravasation of igneous rocks, and above all the extraordinary folding and com- pression to which the beds have been subjected. The confusion is something terrible, and we may regard the district as practically unmapped, although, thanks to Mr. Champernowne and others, a certain amount of correlation with the North Devon beds bas been established. The backbone of the system is constituted by the Great Devon and Plymouth limestones with their associated upper and lower slates, the upper or Dartmouth slates more especially corresponding with the Morte slates of North Devon. Underlying these central beds, or Middle Devonians, are the Torquay Grits, containing the Homalo- notus-beds, some of which struck Mr. Champernowne as being suspiciously like certain Ludlow rocks. These of course are naturally correlated with the Hangman Grits and Lynton Slates. Whether beds as low, or even lower than these, occur in any other part of South Devon, I am not in a position to state; but the beds of Yealmpton Creek have been placed on this horizon, and some geologists have even spoken of Silurian beds in the country north of Tavistock. On the other hand, the Upper Devonian, according to Mr. Champernowne, is represented by the Cockington Grits, originally described by De la Beche as Old-Red Sandstone, and these are the equivalents of the Pickwell-Down beds of North Devon. For Mr. Champernowne the Upper Devonian would appear to terminate with these beds, which he correlates with the Psammites du Condroz. Myr. Ussher, in describing the relations of the Devonian and Culm rocks on the east side of Dartmoor, observes that, as a rule, the Upper Devonian rocks occur in faulted association with the basement-beds of the Culm-measures. But in the area between Bovey Tracey and Bickington the uppermost Devonian beds are irregular slates, similar to the Pilton beds, and in one or two unfaulted junctions they pass up into Culm-measures, which are overlain by indurated shales of the Coddon Hill type. These recent observations of Mr. Ussher would seem to complete the anetey between the Devonian rocks in North and South Devon. ’ Presidential Address—The Geology of Devon. 511 It would be beyond the limits of a Presidential Address if I were to follow this very interesting subject much further on the present occasion. I hope to have demonstrated that considerable progress has been made with the Devonian question during the last twenty years, although, as stated by Mr. Whidborne, in his preface to the “Devonian Fauna of the South of England,” the correlation of the different parts of the system with the major divisions in America and the Continent is still a matter of discussion. Crumpled up and reversed as the beds are in South Devon, their stratigraphy will always be complex; but it is probable that in their original condition there was considerable resemblance to the Rhenish and Belgian Devonians, pointing to the prevalence of fairly similar conditions during the period of deposition. _ Referring to the subject of correlation with Continental beds, there is an article in the “ Neues Jahrbuch” for the present year ‘“‘On the Devonian of Devonshire and the Boulonnais,’ writted by Herr Kayser, which, he says, is the outcome of a trip to the South-west after the Geological Congress of last autumn. Herr Kayser | finds in South Devona development which intimately approaches the West-German. In the Upper Devonian of that region he recognizes nodular limestones with Clymenia (more typically developed at South Petherwin), ‘“ Cypridinen-schiefer,”’ Adorf Goniatite-limestone, Btidesheim-shales, and Iberg Coral- and Brachiopod-limestones. In the Middle Devonian he recognizes Stringocephalus-limestone, Calceola-limestone, Calceola-shales, and possibly also Goslar-beds. In the Lower ‘Devonian he finds the Upper and Lower Coblenz stages and ‘“ Siegen-Grauwacke ” especially represented by a small but typical fauna at Looe. This general agreement is further increased by the appearance of numerous ‘“oreenstones,” which, just as in Nassau and the Harz, are accom- panied by schalsteins. He notes the difference of development in North Devon. In the Upper Devonian the Clymenia-limestone, the Adorf Goniatite-lime- stone, and the Iberg coral-limestone are missing. In the Middle Devonian he notes the absence of the great Stringocephalus- and Calceola-limestones of South Devon. The Lower Devonian of this area, with its preponderance of hard quartzitic sandstones and grauwackes, does not for the present permit of any close comparison with the Rhenish or Belgian-French Devonian. He recognizes the horizons of the Pilton beds and of the Cucull@a-zone, or Baggy beds, which seem to have their Continental analogues rather in Belgium than on the Rhine, but there is nothing in those countries to represent the Pickwell-Down Sandstone. So likewise the phyllitic shales of Morte and Ilfracombe, which alone represent the whole Middle Devonian of North Devon, are equally without analogues. From the above we may fairly conclude that the North-Devon beds have very little in common with the Devonians on the Conti- nent. But it is mainly through the North-Devon Beds, as we have already seen, that the Devonians generally can be made to fit in with the two members of the Old-Red Sandstone. Both geographi- eally and.in character the North-Devon beds occupy an intermediate 512 Notices of Memoirs—W. H. Hudleston— position between the calcareous-volcanic Devonians of the South and the coarse quartzose sediments of the Welsh border, altogether devoid of mollusca. If we regard the “Old-Red” of South Wales as an inshore deposit over an area which was deluged with fresh water from off the land, we can believe that further out to sea, in the times of the Lower Old-Red, conditions were favourable for a moderate amount of marine mollusca. This does away with the necessity for a barrier, and also, in a general sense, it suggests a kind of gradation between the Old-Red, the North Devon, and the South Devon deposits. Bott Rocks, ETc. The age of the crystalline schists of the Bolt.—Besides the mere chronology of the subject, there are questions of considerable interest in connection with these schists, the consideration of which more or less involves the physical history of the bed of this part of the Channel, as well as of the adjacent lands. In this connection also we may endeavour more especially to review the physical structure of the entire South-west, to which allusion has already been made in reference to the effects of the great post-Carboniferous disturbance so obvious throughout Devonshire. The subject generally is by no means ripe for final deeitony and even if we limit our observations, in the first instance, to the Bolt Rocks and their submarine connections, real or supposed, we must allow that, if metamorphism has usually proved an obscure question, the study of metamorphism under water is hampered with additional difficulties. ‘There are no rocks in the county whose age and origin, even to this day, are so much debated as those which, speaking generally, we may term the Bolt Rocks. Of the numerous theories which have been advanced, the most doubtful, it seems to me, is that which regards the mass as the result of progressive metamorphism from the action of underlying or contiguous submarine granite. Allowing, for the sake of the argument, that there is progressive metamorphism, although Prof. Bonney and Miss Raisin distinctly deny it, there is very little in the chlorite- and mica-schists of the Bolt district which resembles the peculiar fringe of partially metamorphic rock due to contact with a granitic mass. Such fringes are usually marked by abundance of andalusite, amongst their other characteristics, especially when slates are invaded. Yet we do not hear of this mineral in connec- tion with the Bolt Rocks, though it must be admitted that the micro- scope has revealed the existence of kyanite, hitherto unsuspected. Let us now for a moment examine the case for progressive metamorphism, which has found a recent advocate in Mr. Somervail. Many of us perhaps, in common with that gentleman, fail to under- stand why all metamorphic rocks, not absolutely the result of contact action, should be claimed as Archean. But this unwillingness to accept their Archean age does not compel us to believe that there has been progressive metamorphism, whereby an extension of the Dartmouth Slates, even with the addition of interbedded igneous rocks, has yielded, under peculiar circumstances, the mica-schists and chlorite-rocks of the Bolt. Mr. Somervail’s argument, that the | Presidential Address—The Geology of Devon. 518 chlorite rocks are the metamorphic equivalents of interbedded sheets of igneous rock on the north side of the syncline, though ingenious, is scarcely convincing. A series of chemical analyses at this stage of the argument would be useful. On striking the balance of evidence it seems probable that the slaty beds are wholly distinct from the true metamorphic rocks in the south. If reliance is to be placed on the microscope, this must be regarded as proved. I would remark also, that few things are more deceptive than an apparent sequence in a highly compressed region; so that the presence of a fault is more often a matter of inference than of direct observation in such districts. It is not absolutely necessary for us to believe that the crystalline schists of the Bolt are of Archean age, if indeed we know exactly what is meant by Archean. But I think that there are fair reasons for considering them to be older than the Devonian against which they abut ; and that, in point of fact, they owe their present position to having been involved in the anticlinal uplift of which there are traces here and there along the channel shores of the Devon-Cornwall peninsula. And this brings me to the consideration of the general structure of Devonshire from a stratigraphical point of view. Regarded as a whole, every one knows that Devonshire is a broad synclinal. The Lower Devonian beds of Torquay on the one side and of Linton on the other are practically on the same horizon, and, omitting minor curves and breaks, the extensive region between these two points is one great trough of Paleozoic rocks. But if we start again from the neighbourhood of Torquay in the direction of Dartmoor, it is still found that, on the whole, newer beds come to the surface as the south-east flank of the granite mass is approached. No matter how the beds in the immediate vicinity of the granite may be affected, the south-east flank of Dartmoor must be regarded as lying in a depression, relative to the coast rocks at the points already mentioned. Again, shifting our position considerably with regard to the central mass of granite, we find a suspicion of Lower Devonian rocks at Yealmpton, and a certainty of them at Looe, all pointing to the conclusion that there are traces of the northern wing of an anticlinal on the Channel coast. An inner and more deeply-seated portion of this anticlinal, in places resulting in a dislocation and possibly an inversion, has brought up the erystalline schists of the Bolt. With these perhaps may be associated inferentially the gneissic rocks in the neighbourhood of the Eddystone, mixed with other crystalline rocks, such as those mentioned by Mr. Arthur Hunt. But if the submarine granite or granites have had no more effect than that of Dartmoor in uplifting the country, they must be regarded as factors of minor importance in the structure of the Channel anticlinal. Of course, the probability of an anticlinal axis in the English Channel has long been recognized, and indeed the space between the Devon-Cornwall peninsula and Brittany is wide enough for many a flexure, the mean result being an east-and-west axis of principal uplift, the exact position of which it is impossible to DECADE III.—VOL. VI.—NO. XI. 33 514 = Reviews —Dr. John Murray—On Marine Deposits. determine. Taking a wide geographical view of the subject, we cannot fail to see that there is, first of all on the north, the synclinal of the Glamorganshire coal-field; next the anticlinal of the Bristol Channel, both being rather limited in extent. The second and central synclinal is that of Devonshire, somewhat bulged by the mass of Dartmoor. The succeeding anticlinal of the English Channel was, in all probability, of a very complex nature, bringing up to-day many old and curious rocks, more or less injected by granites, of which we now have the evidence in the Channel Islands, to say nothing of the traces in the bed of the Channel itself, such as Mr. Hunt has so often brought to the notice of the Association. Beyond this mysterious region of the Channel lies the rocky country of Brittany, which, according to Dr. Barrois, is essentially constituted by a vast geosynclinal depression, running from east to west. The flanks of this great basin consist of very ancient rocks, not quite parallel to each other, but converging somewhat towards the west, and opening out towards the east. The area enclosed has numerous secondary folds, and includes a large series of beds from the Silurian to the Carboniferous. In this region also there are granites, but of more than one age, and Dr. Barrois thinks that they have rather a tendency to follow the anticlinal axes. Brittany, therefore, constitutes our third great synclinal; but in that country a far lower sequence of beds is brought to-day than in Devonshire, proportionate in fact to the much greater area of the country itself. The principal folding movements there also date from Carboniferous times, and thus the entire region, from South Wales to Brittany inclusive, belongs to what we may call the Hercynian system of mountain-making. It is interesting to note that, in the vicissitudes of time, the three synclinal areas still keep their heads above water, whilst the two areas occupied by the anticlinals are submerged—by no means an uncommon geognostic feature. Iam not quite prepared to believe that, on this meridian, the so-called Hercynian system ever attained to any great degree of elevation, though undoubtedly of great width. Its degradation has contributed enormously to the Mesozoic deposits, and in a lesser degree perhaps to the Tertiaries of the country to the eastward. (Zo be concluded in the December Number.) See SER Vi Ta BE VV J.—Marine Deposits ty THE Inpran OcEAN. «On Marine Deposits 1n THE INDIAN, SOUTHERN, AND ANTARCTIC Oceans.” By Joun Murray, LL.D., F.R.S.E. Scottish Geo- graphical Magazine, vol. v. (1889), pp. 405-436, woodcuts 1-12. N November, 1887, Dr. John Murray communicated to the Scottish Geographical Magazine an account of the marine deposits in the deeper regions of the Indian Ocean, mainly based upon materials obtained by Captain J. P. Maclear, of H.M.8. Flying Fish. Subse- quent investigations by Captain Pelham Aldrich in H.M.S. Hgeria, and Captain A, Carpenter in H.M.S. Investigator, in addition to Reviews—Dr. John Murray—On Marine Deposits. 515 recent dredgings off the east coast of Africa for the purpose of laying cables, have furnished the author with ample means for extending the results formerly attained; and, on the present occasion, Dr. Murray ventures to map the area ‘described, carefully marking all the points from which sediment has actually been examined, and those from which sufficient material has been obtained for a chemical and microscopical analysis. The map “represents the Indian Ocean and those portions of the Southern and Antarctic Oceans between the meridians of 20° and 150°H., and is estimated to contain 27,600,000 square miles.” In this area, 415 reliable soundings in depths of 1000 fathoms and upwards are available for study and comparison; and the descriptions and conclusions detailed in the memoir before us form an important addition to the quota of infor- -mation concerning marine sediments already placed by Dr. Murray at the disposal of geologists. se SS “Beyond the 1000-fathom line there is a gradual deepening from the shore, extending southwards and eastwards, the deeper soundings being found in the eastern portion of the region under consideration. The deepest part is, indeed, situated between the equator and the Dr. John Murray—On Marine Deposits. Fic. 2.—Tooth of Oxyrhina hastalis. Fic. 3.—Ear-bone of Ziphius cavirostris. From 2350 fathoms, From 2335 fathoms. Fic. 4.—Section of a Manganese Nodule, Fie. 6.—Spherule of Bronzite. showing ear-bone of Mesoplodon in From 3500 fathoms. (x 26.) the centre. From 2600 fathoms. Fic. 5.—Black Cosmic Spherules, with a metallic nucleus. From 2375 and 8150 fathoms, respectively. (x 60.) Organic Remains and Mineral Bodies obtained from Deep-sea Deposits, Reviews—Geological Survey of Canada. 517 40th parallel of south latitude. South of this the ocean gradually shallows towards the Antarctic Continent.... The zone between 2060 and 3000 fathoms occupies a much larger portion of the whole area than any of the others, and it is estimated that the mean depth of the whole region is about 2300 fathoms.” _ The deposits are classified, as usual, into Oceanic and Terrigenous ; and under the former are included the Globigerina, Diatom, and Radiolarian Oozes, besides Red Clay, while the latter comprise Blue Mud, Coral Mud and Sands, and Green Sands. A brief section of the memoir is devoted to each of these sediments, and a series of detailed descriptions of typical specimens, with lists of organisms, is appended. Among the more striking features, perhaps, is the discovery by - Capt. Aldrich in the Red Clay area of semi-fossil teeth of Sharks and ear-bones of Whales, more or less encrusted with oxide of manganese, as already observed by the Challenger expedition in certain similar | regions of the Pacific and Atlantic Oceans. Through the kindness of Dr. Murray we are enabled to reproduce the figures of four such specimens (Figs. 1-4) obtained by the Challenger; and it will be noted that two, at least, pertain to species characteristic of the Middle Tertiary and, so far as known, no longer existing. The hollow shell of a dental crown shown in Fig. 1, is indistinguish- able from the well-known fossil tooth discovered in the Miocene or Pliocene of nearly all parts of the world, and ascribed to Carcharodon megalodon. Fig. 2 represents a tooth of Oxyrhina hastalis, which seems to have an equally wide distribution in Tertiary formations ; and another tooth, not figured, is very suggestive of the so-called Otodus obliquus of the London Clay. The Cetacean ear-bone shown in Fig. 3 is identified with the existing Ziphius cavirostris; and Fig. 4 gives a view, in section, of a manganese concretion formed round an ear-bone of Mesoplodon. Small spherules, with metallic iron as a nucleus (Fig. 5), regarded as of cosmic origin, are also found in the Red Clay; and numerous small mineralogical curiosities, including granules of bronzite (Fig. 6), are mingled with the same sediment. ‘‘There are indications that volcanic disturbances have taken place at the bottom in these regions, but at a remote period rather than recently.” A. 8. W II.—Guotogican anp Narurat History Survey or Canapa. Con- TRIBUTIONS TO CANADIAN PaLtzontoLtoey. By J. F. WHITEAvEs, F.G.S., etce., Palzeontologist and Zoologist to the Survey. Vol. I. Part II. 8vo. pp. 90-196, plates xii—xxvi. (Montreal, W. F. Brown & Co., 1889.) ART I. of this series’ contained only one memoir; the present consists of three, vizi—(1) On some Fossils from the Hamilton Formation of Ontario, with a list of the species at present known from that Formation and Province; (2) The Fossils of the Triassic Rocks of British Columbia; (8) On some Cretaceous Fossils from British Columbia, the North-West Territory and Manitcba. 1 Reviewed in the Grou. Mac. March, 1886. 518 Reviews—G'eological Survey of Canada. Advance copies of the letter-press of these memoirs have already been distributed, pages 91-1221 having been issued in September, 1887; pages 123-150 in December, 1888; pages 151-184 in © June, 1889; while the remainder, or pages 185-196, are dated August 1, 1889. . It may fairly be questioned whether paleontological science is in any way benefited by the practice of issuing advance copies of descriptions of fossils, without any figures to assist in their inter- pretation. The object of so doing, viz. to secure priority to the author of the species, is, of course, a perfectly legitimate one, but who that has attempted to picture to himselt, from a description alone, the form, say of an Ammonite, with all its intricacies of sculpture and suture-line, will not admit that the task has been in too many cases a hopeless one? Good figures have now become indispensable for the accurate identification of species, and not only do new species require them, but many old ones should be refigured from the original types. Such work would greatiy lighten the labours of the paleontologist. However, the volume now under review is amply supplied with figures of all the new species described, in a series of excellent lithographic plates, whose execution reflects much credit alike upon the artist and the lithographer. The first paper of the series enumerated above contains descriptions of Corals, 1 species, of Crinoids 11, of Blastoids 5, of Brachiopods 11, of Lamellibranchs 2, of Gasteropods 6, of Trilobites 1, and of Fishes 1. Of these the following are considered to be new to science, viz. Taxocrinus lobatus, Hall, var., (unnamed), Homocrinus crassus, Dolatocrinus Canadensis, Pentremitidea filosa (doubtfully new), Lingula Thedfordensis, Spirifera subdecussata, Platyostoma plicatum. These are followed by a useful list of fossils from the Hamilton Formation (Middle Devonian) of Ontario. The author acknowledges his indebtedness to Mr. Charles Wachs- muth for the identification of three species of Crinoids, “as well as for valuable critical suggestions in reference to the Crinoids and Blastoids generally.” It is a pity that so competent a conchologist as Mr. Whiteaves should not have taken upon himself to decide the point as to the affinities of the fossil named by de Verneuil, and later by Professor James Hall, Turbo Shumardi, figured on plate xvi. (fig. 8) of the present memoir. Mr. Whiteaves goes no further than to observe that ‘the reference of this shell to the Linnean genus Turbo does not seem entirely satisfactory, and it is not easy to define in what particular it differs from Platyostoma.” The second memoir “On some Fossils from the Triassic Rocks of British Columbia” is prefaced by a brief account of the geo- graphical range of some of the typical species collected, one of which, a species of Halobia, is of interest as coming from the most northerly locality on the continent of North America (the Stikine River), from which Triassic fossils have yet been obtained. 1 Pages 1-90 are contained in Part I. of these Memoirs. Reviews— Geological Survey of Canada. 519 The collection of the Triassic fossils of British Columbia now contained in the Museum of the Survey consists of 8 species of Brachiopoda, 5 of Lamellibranchiata, 1 of Gasteropoda, and 8 of Cephalopoda, besides some undeterminable fragments of Pentacrinites. Of these the four following are identified with previously described species, viz. Terebratula Humboltensis, Monotis subcircularis, Halobia * (Daonella) Lommeli, and Arcestes Gabbi ; the remainder are regarded as new, or of uncertain affinities, viz. Spiriferina borealis, Terebratula Liardensis, Monotis ovalis, Halobia occidentalis, Trigonodus (?) productus, Margarita Triassica, Nautilus Liardensis, Popanoceras MeConnelli, and variety lenticulare, Acrochordiceras (?) Carlottense, Trachyceras Canadense, Arniotites (species uncertain), Arniotites or Celtites (species uncertain), Badiotites Carlotiensis. Most of the _ species of Cephalopoda described as new were examined by Professor A. Hyatt, of Boston, whose observations regarding them are appended to Mr. Whiteaves’ descriptions. The new genus Arniotites, Hyatt, is here jointly described by Mr. Whiteaves and Professor Hyatt, the latter regarding it as the equivalent of the Balatonites arietiformes of Mojsisovics. The type-species is the Celtites (?) Vancowverensis of Whiteaves, described in Dr. G. M. Dawson’s “ Report of a Geological Examination of the Northern Part of Vancouver Island and Adjacent Coasts” (Ann. Rep. Geol. Surv. Canada for 1886, p. 110 B.) The third memoir—On some Cretaceous Fossils from British Columbia, tae North-West Territory and Manitoba—is divided into the following sections, viz. (A.) ‘‘From the Harlier Cretaceous of British Columbia,” in which the following species occur :—Aucella Mosquensis, var. concentrica, Yoldia arata, Whiteaves, Astarte Car- lottensis, n.sp., Opis Vancouverensis, Whiteaves, Placenticeras occt- dentale, Whiteaves, P. Perezianum, Whiteaves, P. (Perezianum ? var.) Liardense, and Scaphites Quatsinoensis, Whiteaves. (B.) “From the North-West Territory.” (1.) From Rink Rapids. on the Lewis River, a tributary of the Yukon, in Latitude 60° 20’ and Longitude 136° 80’; collected by Dr. G. M. Dawson in 1887. The following species are recorded from this locality :—Discina pileolus, n.sp., Cyprina Yukonensis, n.sp., Schlenbachia borealis, n.sp. ?, LEstheria bellula, n.sp. (2.) From the Rocky Mountains, three miles north of the east end of Devil’s Lake; collected by R. G. McConnell in 1887. The fossils here obtained are said to be “‘ probably from the same geological horizon as the Lower Shales and Sandstones of the Queen Charlotte Island Cretaceous,” and consist of the following, viz. Terebratula robusta, n.sp., Ostrea Skidegatensis, Whiteaves. Exogyra (species undeterminable), Lima perobliqua, n.sp., Pteria (Oxytoma) Corneuiliana, d’Orbigny, Inoceramus, Trigonoarca tumida, Whiteaves, Trigonia Dawsont, Whiteaves, Astarte Carlottensis, Whiteaves, Proto- cardium Hillanum (?) var., Cyprina occidentalis, Whiteaves, Pleuromya Carlotiensis, Whiteaves, Schlonbachia borealis, Whiteaves, S. gracilis, n.sp., Belemnites (species undeterminable). (8.) From the Peace River, a few miles below Fort Vermilion ; collected by Mr. W. Ogilvie, D.L.S., in 1885, 520 Reviews—Prof. A. Pavlow—Secondary Rocks of Russia. Only one species was collected in this locality, viz. Placenticeras glabrum, n.sp. (4.) From the Fort Pierre Group of the Later Cretaceous Rocks of the Saskatchewan and its tributaries; collected by J. B. Tyrrell in 1885 and 1886. From this locality the following species were obtained, some of which were described in Mr. Tyrrell’s Report in the Annual Report of the Survey for 1886 (vol. ii. new series, pp. 153-163 E), but without figures, a want which is here supplied :— Pteria linguiformis, var. subgibbosa, Meek, Inoceramus Sagensis, var. Nebrascensis, Owen, I. Vanuxemi, Meek & Hayden, Gervillia recta, var. borealis, Whit- eaves, Tancredia Americana, Meek & Hayden, Cyprina ovata, M. & H., Cyprina subtrapeziformis, Whiteaves, Protocardia sub- quadrata, Evans & Shumard, Protocardia borealis, Whiteaves, Linearia formosa? Meek & Hayden, Pholadomya subventricosa, M. & H., Liopistha undata, M. & H., Solecurtis (Tagelus) occidentalis, Whiteaves, Martesia tumidifrons, Whiteaves, Hydatina parvula, Whit- eaves, Lunatia concinna, Hall & Meek, sp., Baculites ovatus, Say, B. grandis, Hall & Meek, B. compressus, Say, Scaphites nodosus, Owen, Placenticeras placenta, Dekay, sp., Paleastacus (?), ornatus, Whiteaves, Tooth of a Selachian. (C.) ‘ From Manitoba.” From the Niobrara-Benton Formation of the Later Cretaceous in the Duck and Riding Mountain District. Here the following species have been collected:—Serpula semicoalita, u.sp., Lingula sub- spatulata (?), Hall & Meek, Ostrea congesta, Conrad, Anomia obliqua, Meek & Hayden, Inoceramus problematicus, Schlotheim, Modiola tenwisculpta, n.sp. (?), Belemnitella Manitobensis, n.sp., Loricula Cana- densis, n.sp., Ptychodus parvulus, n.sp., Lamna Manitobensis, u.sp., Enchodus Shumardi, Leidy, Cladocyclus occidentalis, Leidy. ALOR, IIJ.—Nores on THE Jurassic AND CRETACEOUS STRATA OF Russia AND Hwenanp. By Prof. A. Paviow. ErupEs sur Les CovucHEes JURASSIQUES ET ORETACEES DE LA Russiz. J. JurassiquE Supérieur ET Oritackt InririeuR DE LA RUSSIE ET DE L’ANGLETERRE. Par le Prof. A. Paviow. Bulletin de la Soc. Imp. de Moscow, 1889, No. 1, pp. 61-127, 176-179, Pls. II., ITI., IV. ONFLICTING opinions touching the relative age and position of a series of strata in the higher portion of the Jurassic and the lower portion of the Cretaceous in the Hast of Russia, have for a long time existed among Russian paleontologists, and curiously enough the question as to the proper correlation of the strata on the same horizons in this country is still a debated point, as shown in the excellent paper “On the Subdivisions of the Speeton Clay,” brought recently before the Geological Society by Mr. G. W. Lamp- lugh. Prof. Pavlow has studied for many years the Russian beds, developed more particularly near Simbirsk on the Lower Volga, and in the neighbourhood of Moscow, and last year he made a personal Reviews—Prof. Fouqué on Earthquakes. 521 examination of the section at Speeton, and of the fossils therefrom _ in the Woodwardian and other museums of this country, with the result of discovering a very close resemblance in the fossils and petrographic character of these beds in the two countries, so that there can be no doubt that they should be considered as synchronic or homotaxial. The points of similarity and difference in the deposits and the fossils are discussed in considerable detail in the present paper, and the following are the conclusions arrived at by the author : (1) The beds with Perisphinctes virgatus of the Hast of Russia immediately overlie the strata with Hoplites eudoxus and Hxogyra virgula (Middle Kimmeridge), and are intimately related to these latter. (2) The Russian strata with Perisphinctes virgatus, correspond to the Upper Kimmeridge of English geologists (Blake), to the Lower Portlandian, and, in part, to the Middle Portlandian of the French geologists (Loriol). (8) The zone of Olcostephanus triplicatus, or the Lower Portland of Blake, exists in the Russian Jura, and serves as base to the beds with Oxynoticeras catenulatum (the first étage of Rouillier). (4) Judging by its stratigraphical relations, this first étage with O. catenulatum, cannot be more recent than the Upper Portland. (5) The bituminous schists of the Province of Simbirsk and those of Speeton are on the same geological horizon. (6) The zone of Belemnites lateralis, Phill. (corpulentus, Nik.), of Simbirsk, and the first étage of Rouillier, correspond to the zone at Speeton of this same fossil, and, consequently (7) the Bel. lateralis zone at Speeton corresponds to the Upper Portland of the South of England. (8) The gravels of Spilsby, Lincolnshire, are nearly equivalent to the Bel. lateralis zone of Speeton, and to the corresponding beds in Russia. (9) Between the zone of Bel. lateralis (corpulentus) and the Neocomian beds of Simbirsk there is a well-marked unconformity, which (10) nearly coincides with the epoch of Hoplites noricus and Bel. jaculum (type). (11) The zone at Speeton with Amm. speeton- ensis corresponds to the lower part of the Neocomian clays of Simbirsk (clays with Olcost. versicolor and Inoceramus aucella). (12) The fauna of the higher stages of the Russian Jura (first and second étages of Rouillier, Volgien inférieur et supérieur) is so intimately allied to that of the corresponding stages in England, that it is possible and desirable to adopt a common stratigraphical classification for the two countries. The author further shows in tabular form the corresponding zones in the two countries, and describes and figures some of the principal fossils, including new species of Olcostephanus from Swindon, and Spilsby, as well as from Simbirsk. IV.—Pror. F. Fovaué on Harraquakes. Les Tremptements pe Terre. By F. Fovqut, Membre de l'Institut (Académie des Sciences), Professeur au College de France. 828 pp. (Paris, J. B. Bailliére et Fils, 1888.) S the whole of Prof. Fouqué’s book will repay a careful study, this notice may be confined to one or two passages that seem to me to admit of improvement, and a few others as being worthy of especial attention from geologists. 522 Reviews—Prof. Fouqué on Earthquakes. In a recent work on Earthquakes, we should expect to find a fair discussion of some of the excellent seismographs which have lately been invented in Japan and other places. M. Fouqué excuses him- self from the task of writing such a chapter (pp. 7-8), partly on the ground that the subject deserves to be treated in a separate work 5 partly because improvements are continually being made in these instruments, and their description will gain by being deferred for some years. If this latter principle were consistently carried ove, how many works on natural science would ever see the light? But the influence of these reasons is not very apparent. For the average length of one of M. Fouqué’s chapters is a little less than 18 pages ; and the scattered references to seismographs and other instruments amount to rather more than 20 pages, excluding the description of those used in the experiments on the velocity of earth-waves. Now, of these twenty pages, seven are devoted to Cavalleri’s seismoscope — and some of the results that have been obtained with it. But, owing to the fact that the period of vibration changes during an earthquake, and to the natural defects of the instrument itself, these pages are of little value. Of other instruments alluded to, the accounts are too short and incomplete to be of much use, and in only one case is the description accompanied by a figure. It is to be hoped therefore that, in a new edition, M. Fouqué will see his way to replacing these twenty pages by a chapter in which a few of the more trust- worthy seismographs are exactly figured and described. In the chapter on the “centre of disturbance,” the approximate and imperfect nature of our methods for determining its superficial position and depth is carefully pointed out. The method employed by Messrs. Dutton and Hayden, in the case of the Charleston earthquake, is however quoted with some approval. But this method makes the depth of the centre independent of the intensity of the initial disturbance. For instance, in every earthquake originat- ing at a depth of 34 miles, the intensity would, if the method were correct, decrease most rapidly at a distance of about two miles from the epicentrum. But we can imagine the intensity of the earth- quake to be so feeble initially that it cannot, by the most delicate instrument yet constructed, be felt at so great a distance from the epicentrum, or perhaps even be felt at the surface at all. The method is thus unreliable, however carefully applied. Perhaps a more accurate statement of it would be that it gives an inferior limit to the depth of the seismic focus. Microseismology, one of the latest and most fascinating develop- ments of the science, is dismissed in a short chapter of a dozen pages. Half of the chapter is allotted to the perturbations of magnetic in- struments during earthquakes. But, whilst these interesting pages could ill be spared, might we not have expected a fuller account of the other advances that have recently been made? Such a chapter must surely be incomplete when the names of Bertelli, the founder of microseismology, of d’Abbadie, and the Darwins are not so much as mentioned. The rotation of columns during earthquakes is an interesting Reviews—Reynolds’s Geological Atlas. 523 historical problem, and M. Fouqué adheres to the original explana- tion of Mallet. He seems (p. 55) to doubt the real existence of vorticose shocks, whereas it is evident, as was shown some years ago in this Macazinz (Vol. IX. 1882, pp. 257-265), that such shocks in the neighbourhood of the epicentrum are a necessary consequence of a large seismic focus, and may be one of the causes of the rotatory movement so frequently observed. The cause suggested by Mr. Gray is probably, however, that which acts most widely in producing this effect. It would be difficult, within reasonable limits, to point out the many excellences of Prof. Fouqué’s book. But as, in this country, it will probably be read chiefly as a supplement to that written by our leader in seismology, Prof. Milne, it may be well to note the passages that, in this view, will best repay perusal. First and fore- most is the admirable treatment of the relations between earthquakes and geological structure, the evolutionary aspect of the science (pp. 9-80, 189-201). Here we have discussed and summarized the work of Suess, Héfer, von Lasaulx, Hoernes and others, as well as some of the earlier results obtained by the Swiss Seismological Commission. The subject of seismic periodicity is considered with great fullness in Chapter x. The useful list of questions drawn up by Prof. Heim for aid in the study of earthquakes is reprinted in Chapter viii. The velocity of earth-waves occupies a long and interesting chapter, and includes an account of the valuable experi- ments made by the author in conjunction with M. Lévy. Lastly, the second part of the book (pp. 249-326) contains a description of a few of the more important earthquakes that have happened between 1854 and 1887. The illustrations, with one or two exceptions, are good; and among them may specially be noticed the maps of the Swiss earth- quakes of Nov. 1879—Dec. 1880, and of July 22, 1881, the Charles- ton earthquake of August 31, 1886, and the Andalusian earthquake of Dec. 25, 1884. C. Davison. V.—Reynotps’s Gronocican Arias or Great Brirarn. Com- prising a series of County Maps geologically coloured from the best authorities.! Second Edition, 1889. Aas book which calls for a new edition, by reason of its intrinsic IG value, is worthy of notice. A new edition of the well- known Geological Atlas of Great Britain, published by Messrs. Reynolds & Sons, 174 Strand, has just been issued. ‘This atlas comprises 82 county maps geologically coloured and arranged alphabetically, the colours depicting the varied geological features of each county are mainly those used on the published maps of the Geological Survey. Every county is carefully coloured, and the colours numbered 1 Published by James Reynolds & Sons, 174 Strand, 1889. 524 Reviews—Reynolds’s Geological Atlas. according to the legend for geological reference separately given at the commencement of the atlas, of which there are 30 divisions. The execution of the maps geologically and topographically leaves little to be desired; this atlas, in fact, forms a most perfect pocket travelling companion, combining both convenience and portability, with clearness and accuracy ; we commend this work to all travellers in Great Britain. Advantage has been taken of the advanced state of the Geological Survey maps, to correct and re-draw the geological lines, and depict the solid geology as accurately as possible. The want of a new edition of this atlas has long been felt by those who have used the first one, its completeness and portability for ready reference either for the library or as a companion in the field, render it indispensable. Hach map is accompanied by a small skeleton index to the. numbered and published sheets (4 or whole) of the 1-inch geological maps of the Survey, and the divisional lines upon each of the maps of the atlas also correspond to the area occupied by them. This enables any one to order the special maps of the Survey from which the 82 counties in the atlas have been constructed. Marginal notes are appended to each map, denoting the places of occurrence of the more important organic remains, as well as of the economic minerals met with in the county. Examination of maps 8, 10 and 11, or, indeed, any others, will readily show the usefulness and value of these notes to those seeking mineralogical, geological, or paleontological information. Twenty-three pages of letterpress (p. 1-23), containing short geological descriptions of the 82 maps, will be found of value and interest, as affording a short description of the structure of each county. Pages 24-82 are devoted to the mineral products of Great Britain, their distribution and value. Agricultural geology and water supply receive attention. A most admirable tourists’ guide of 10 pages, giving the chief places of interest, finest views and scenery, fishing stations and streams, etc.; indeed, in relation to each of the 32 counties, matters of much general interest and use are given. Probably no other work of the kind will so readily commend itself to, or meet the requirements of, the traveller by rail or road, and the construction of the maps will satisfy the most critical, as fulfilling the purpose for which they are published as an atlas of England geologically illustrated. A geological map of Scotland accompanies the atlas; it is to be regretted that Messrs. Reynolds & Sons did not prepare an equally good geological map of Ireland to accompany it. We recommend this extremely good and well-got-up book to all who desire to know something of the geological structure of Great Britain. Reviews—Reynolds’s Map of the Environs of London. 525 VI.—Nerw Mar or tHE Environs or LONDON GEOLOGICALLY COLOURED. SCALE 4-INCH To THE MILs.’ HIS will prove to be a very useful Geological Map of the London area. The high price of the two 1-inch maps of the Geological Survey illustrating the same district deters many from possessing a reliable map of the complicated geological structure of the London Basin. This map issued by Messrs. Reynolds & Sons quite supplies the want. The geological lines are correctly laid down, being taken and reduced from the larger one-inch Ordnance Geological Map. London in both cases is placed in the centre of the sheet [this was expressly arranged in the Survey map for the convenience of its many inhabitants]. The two maps issued by the Geological Survey exhibit two important features over the London area, one showing the solid geology and the other the superficial or more modern Post-Pliocene accumulations; this is partly done on the map before us, but to have placed all the Quaternary sands, gravels, and clays (as depicted on the Survey map) on this map (on half the scale) would have been at the expense of clearness of definition. The superficial area of the map is 2280 square miles or 60 miles by 38. London being in the centre, gives a radius of 30 miles east and west, and 19 miles north and south; concentric lines four miles apart denote distance in miles from the centre of London. The east and west of the country illustrated extends from Long Reach east of Chatham to Laurence Waltham west of Maidenhead. Latitudinally the area extends from Godalming, Guildford, and Tunbridge on the south, to St. Albans and Chelmsford on the north. The area covered by the one-inch Survey map is 1144 square miles or 44 by 26 miles; thus Messrs. Reynolds’ map contains geological information over 1186 more square miles than the Government sheet. The structural or physical lines are care- fully laid down over the entire map, the geological epochs shown on the map, ranging from the Weald Clay to the Post-Tertiary, or Post- Pliocene beds of the Thames Valley, etc., all the railways are well defined, a desideratum for scientific as well as ordinary travellers, and the stations are prominently marked. The colours illustrating the geological formations are numbered to correspond with the legend, thus leaving little to be desired as a thoroughly convenient map of the Environs of London both topo- graphically and geologically constructed. Thirty-three pages of letterpress accompany the map, naming and ‘describing no less than 152 places of interest within the radius of 30 by 19 miles, being a clear and general history of the more remark- able places in the counties of Middlesex, Surrey, and Hssex. On p: 15 a short account is given of the geology of the London area, tersely explanatory of the varied geological formations that occur within the area depicted. We commend this map, published by Messrs. Reynolds & Son, to all residents in London and its environs, also to travellers and geological students. 1 Published by James Reynolds & Sons, 174, Strand, 1889. 526 Obituary — Charles Spence Bate. CORRESPONDENCE. RATE OF SUBAERIAL DENUDATION. ’ Srr,—Referring to Mr. Davison’s paper in the September Number of the GronogrcaLt Magazine, it will not do, as I have endeavoured to show in ‘Stellar Evolution,” to take the average rate of denudation of the seven river basins which he names, as in any way represent- ing the mean denudation of the whole earth. The majority of these rivers are exceptionally muddy, indicating a very high rate of denudation: much above that of the whole earth. PERTH. JAMES CROLL, ~ THE FULLERS EARTH OF NUTFIELD. Erratum.—Mr. P. Gerald Sanford regrets that some mistakes occurred in the setting up of the figures of his analysis of the ‘ Fullers’ Earth.” Grou. Mac. October, 1889, p. 456, which he desires now to correct. No. 1. Buuve Earrs. Dried at 100°C Insoluble Residue. Insoluble Residue 69-96) per cents —isiO> = 62°81 per cent. Oxide of iron, Fe,0, = 2°48 INO ee BG yk Alumina, Al,03 = 3°46 e503) =) 15380, Lime CaO = &§ 87 CaO = 188) op Magnesia, MgO eee MgO = OG >: Phosphoric acid, P20, = 0°27\ Solube -—— Sulphuric acid, SO; = 0°05/ in acid. 69-96 Sodio Chloride, NaCl = 0:05 Alkalies, K20 Ss Word Combined Water = 15-57 99°86 P. G. SANForRD. OS ao PASE pa CHARLES SPENCE BATE, L.D.S.R.C.S. Ene. F.R.S., Ete. Born 16 Marcu, 1818; Diep 29 Juty, 1889. Cuarues Spence Bate was born at Trennick, Truro, on the 16th March, 1818. He was the eldest son of Mr. Charles Bate, who for many years practised as a dentist in Plymouth. He was educated at the Truro Grammar School under the late Dr. Ryall. On leaving school he entered the surgery of Mr. Blewett, where he remained about two years; he then devoted himself to the study and practice of dentistry with his father. After becoming duly qualified, he removed, in 1841, to Swansea, where he soon acquired a consider- able practice. While at Swansea he developed an ardent love for Natural History, by his knowledge of which he afterwards became distinguished. He was speedily associated with all the scientific men of the place; and on the occasion of the visit of the British Association to the town in 1848, he took an active part in arranging for the reception of that body, and became one of its members. On more than one occasion subsequently he was President of one of the Sections. He was mainly instrumental in securing the visit Obituary—Charles Spence Bate. 527 of the British Association to Plymouth in 1877; and as one of the Vice-Presidents at that meeting, he contributed largely by his liberal exercise of hospitality to make the gathering a success. In 1851 Mr. Spence Bate left Swansea and returned to Plymouth, taking up his residence at 8, Mulgrave Place, where he succeeded to the practice of his father as a dentist, in which profession he was almost unrivalled. He was the author of many works on dentistry, which appeared separately, or in the “ Lancet,” the “ British Journal. of Dental Science,” and the “ Medical Gazette,” and in the “ 'Trans- actions of the Odontological Society,” to the Presidency of which he was elected in 1855. Two years previously he had been President of the British Dental Association. In 1881 Mr. Spence Bate was a Vice-President of a section of the Medical Congress. He was Honorary Surgeon-Dentist to the Plymouth Dental Dispensary and other local Institutions. Nor was it only in dentistry that Mr. Spence Bate became celebrated. He devoted a large amount of time to the investigation of the habits of marine animals, and, in conjunction with Mr. I. O. Westwood, was the author of a most important work on the “ British Sessile-eyed Crustacea.” The value of this work was fully recognized by the scientific world, and for this and other Memoirs on the Crustacea, Mr. Bate was elected a Fellow of the Royal Society in 1861. Other works by him on the same subject were a British Museum “ Catalogue of Amphipodous Crustacea,” and a ‘“‘ Report on the Crustacea Macrura, collected by H.M.S. ‘Challenger,’”’ during the cruise of that Vessel round the world. This last-named work was only completed a year ago, and forms a most valuable con- tribution to carcinological science. He was keenly interested in all scientific matters connected with the town of Plymouth and county of Devon, and earnestly exerted himself to promote their progress and success. The restoration of the Plymouth Institution to its present healthy activity, after a period of comparative inertness, must be mainly ascribed to him. lected a member of the Institution in 1852, he became Secretary 1854—60, President in 1861—62 and 1869-70, and Member of Council 1853-83. He served as Museum Curator at different times, and as Editor of the Transactions in their present form 1869-83. He delivered no fewer than thirty lectures and Presidential Addresses between 1858 and 1882 to this Institution. Mr. Bate was one of the founders of the Devonshire Association, and during the first year of its existence (1862) was Senior General Secretary. In the following year he vacated this post, having been elected to the office of President of the Association. He delivered his Presidential Address at the Annual Meeting at Plymouth in 1863, and qualified as a permanent member of the Council. He was seldom absent from the annual meetings, and never ceased to take the liveliest interest in the progress of the Association. Between 1862 and 1878 he contributed eleven papers to its Proceedings. He was an Honorary Member of the Torquay Natural History Society, Honorary Member of the Teign Naturalists’ Field Club, and likewise Honorary Member of the Royal Institution, Truro. 528 Miscellaneous—Marble Quarries of the Island of Paros. Mr. Spence Bate took great interest in Art, and was not only a promoter, but also a working member of the Plymouth Fine Art Society. He also took a warm part in the Plymouth School of Art, and in the carrying out of the new Art, Science and Technical Schools about to be erected as a Jubilee memorial in Plymouth. Mr. Bate naturally felt a keen interest in the Marine Biological Association, and was very active and energetic in promoting the establishment of their Marine Biological Laboratory recently erected at the Plymouth Citadel. Some years since he purchased a country residence, called the Rock, at South Brent. There he died, after a brief but painful illness, on Monday, the 29th July, 1889, aged 71 years. Mr. Bate was twice married. His first wife was Miss Hele, of Ashburton. She died in 1884. His second wife, to whom he was married about two years ago, survives him. He also leaves two sons, one of them, Captain McGuire Bate, of the Royal Engineers ; the other, Dr. Hele Bate, of London, who was with his father throughout his last illness; and one daughter, Miss Bate, who has inherited much of her father’s artistic taste. The titles of 52 papers by Mr. Spence Bate are given in the Catalogue of Scientific Papers published by the Royal Society, vols. i. and vii. 1867 and 1877. One of his most valuable researches was published in the Phil. Trans. Roy. Soc. 1858, p. 589-606, on the development of Carcinus moenas, but his ‘‘ Challenger” volume was his last and greatest labour. The loss of one possessed of such varied and brilliant talents cannot fail to be both widely and severely felt amongst men of science generally and by a large circle of friends by whom he was greatly and justly esteemed. IMEI SS CA ep ewecan paso) oS. Tuer Istanp or Paros, IN THE CYCLADES, AND ITs MarBiE QuArnrizs.! The Island of Paros is eleven miles long and eight miles broad at its widest part. There is a broad belt of nearly level land round the coast ; but the interior is moun- tainous, rising to a height of 2530 feet at Mount St. Elias (probably the ancient Mount Marpessus). The northern and western parts consist of schist and gneiss, granite appearing also in the environs of Parekhia. ‘The southern part of the island consists chiefly of crystalline limestone. There is no evidence here of the age of this limestone; but that of Attica is now known to be Cretaceous, and probably that of the Cyclades is of the same age. The finest statuary marble, or /ychnitis, varies from five to fifteen feet in thickness at the quarries of St. Minas ; it occurs in a bed of coarse- grained white marble, with bluish black veins. The coarse marble becomes dark in colour near the lychnitis, both above and below it, and thus the layer of statuary marble is distinctly marked off. The dark colour is due to traces of binoxide of manganese and magnetic oxide of iron. It seems probable that the impurities have been withdrawn from the lychnitis and have become concentrated near the edges of the adjacent seams of limestone. The rocks are much disturbed and folded, and often dip at right angles. The ancients avoided the marble lying near the axis of elevation, that being of less good quality than in other parts. A Greek company formed a few years back to work the marble attacked it here, where it could be got at least expense; this discredited the marble in the market, and the company failed, having spent over £160,000 in a railway, landing-pier, and elaborate installation of various kinds. There is a good deal of excellent coloured marble in the island ; but, not having been used by the ancient Greeks, this is little known. Rogpert Sway, F.C.S. ! From British Association Reports, Section C. (Geology), Newcastle Meeting, Sept. 1889. THE GEOLOGICAL MAGAZINE. NEW SEBRIES@* DECADE: IH’ VOEM Vir No. XII.—DECEMBER, 1889. On Sve SEIN IaIb) WSL ICG Ibs — T.—Nortrs on THE Ponza IsnLANDs. By H. J. Jounston-Lavis, M.D., B.-és-Se., F.G.S., ete. [ 1884 I spent about a fortnight investigating the geological structure of these islands, and intended to have to a certain _ extent completed my studies at that time. Cholera was then raging at Campobasso on the mainland, and the islanders, not comprehending the curious habits of a travelling geologist, supposed I had been sent by the Government to spread the “‘ Cholera Powder,” and requested me to leave the islands by the next steamer. This I naturally for safety’s sake did, and opportunities for returning to the locality not having again presented themselves to me, and lest I should forget some of the interesting observations I then made, I think it desirable without further delay to record what I then saw. This is all the more important since my own observations differ considerably from those of the few other observers of the geology of these islands, or include facts which they do not mention in their writings. Santo Stefano is of exceeding interest from the very clear sections which its steep cliffs near the Cemetery present. The following are the details of the section : M. (2) Breccia with vegetable soil and modern pottery together with made earth Be 1°50 (2) Compact brown tufa with weathered pumice, probably an old vegetable soil 1:30 (ec) Ditto, but not compact and ‘containing concretions, especially at bottom, where it is a little more sandy . 1-10 (Z) Two or three pumice-beds with intermediate ash-beds irregularly inter- bedded and concretionary along fissures He 606 coo BAO (¢) Dust-bed somewhat irregularly reposing on pumice-bed _ naa ... 0°50 (f) Pumice-bed, the lower partis about m.0:10... .. 0°65 (g) Black sand or lapillo bed ee stratified ; coarser as it ‘graduates down to next... S00 200 on 500 ot sete .. 0°55 (z) Pumice and pumiceous scoria ast 306 ae w» 0°55 (2) Earth buff fine-bedded pumice, with lapilli Bi athe aus ae ... 0°30 (7) Loose pumice and lapilli_ ... . 0:90 (4) Very fine buff dust, finely stratified, containing ‘bits of pumice and is also concretionary 1-00 (7) Slightly concretionary dust- “bed, yellow at top, purple-brown at bottom and graduating thence into fine stratified dust ; the yellow bed is an old vegetable soil with concretions that have formed around roots and fills in the eroded surface of the purple-brown bed, Oiehowing weathering had occurred at the surface... oe p06 a8 deputies (m) Fine lapilli with Speen bands... nae 00 ode aOR (x) Pumice-bed . : yen wes Ea, Sets ses hs sco ON (0) Fine black scoria ... aes 500 «= O°14 3 .. 0°28 (y) Fine greenish-grey dust with band of lapilli at bottom ... DECADE Ill.—VOL. VI.—NO. XII. 34 530 Dr. H. J. Johnston-Lavis— The Ponga Islands. (q) Ivregular finely peccostonally) brecciated yellow earth ; probably an old concretionary soil 1:00 (r) Ochre-stained pumice ; the upper ten centimetres are less stained, have larger fragments with pyroxene crystals and ejected blocks ... ane Ogu) (s) Brown earth with concretions, finer at the top and passing down into 2°60 (¢) Same as last, lighter in colour with intermixed ieee which at some spots forms a band es Ses 2a fae ane an on odeo0 («) White dust not concretionary ... 900 ire wide 0 ec eOROU (v) Brown pumice a ea te see anOk2D (w) Pumice bed with lapilli and few ej jected blocks ... a 309 soa ZOD (2) White pumiceous dust-bed .. one goo Pile) (y) Pumice-bed with light buff concretionary ‘dust-bed in middle... ne) 18a) a White pumiceous dust-bed .. a8 Be 908 Bees 10°) (zz) Trachyte forming main mass of the island. The main body of the island is composed of a mass of trachyte which seems to have oozed forth as a compound dome. The flow arrangement resulting from this is well shown as the rock exhibits a distinct pipernoid structure. Doelter has fully described?’ this rock both from a chemical and microscopical point of view, but says little of the overlying strata of pumices, lapilli, dust and earth. These all point to a considerable number of explosive eruptions in the vicinity, as there are no signs of a crater of explosion visible on the island itself. That during the deposition of these tuffs the island was above the water is proved by the numerous vegetable soils, roots preserved by concretions, surface erosion, ete. That the explosive eruptions extended down to the metamorphosed limestones beneath the volcanic platform from which occurred the explosive eruptions is proved by the few ejected blocks met with in the tuffs. The ejected blocks also include lava fragments like the underlying trachyte and the dolerite of Ventotene, but most interesting is a leucitophyre, no massive remains of which have been discovered in the islands. The latter, nevertheless, is another addition to the widely-distributed localities of Italy in which leucite forms an important rock constituent. Loose blocks have been found in tuff at Procida, but so far leucite rocks have not been recognized in Ischia or the Ponza group of islands. Ventotene is also exceedingly interesting, as the continuous cliff section stretching round it clearly reveals its structure. The follow- ing is a compound section of the island, beginning from the most superficial deposits :— M. (1) Vegetable soil, rich in snail shells = (2) Blown sand of. powdered sea shells with many snails, chiefly H. Cantiana. It is very full of concretions . 4:00 (3) Brown earth with concretions especially at bottom, often with bands of blown sand coo 0D) (4) Compact yellow tuff, used for carving into portable “furnaces, passes down to... : 4 to 7:00 (5) Compact grey dust and pumiceous s scoria with bands of loose pumiceous scoria in the middle : 208 a 360 ae soa WOK (6) Scoriaceous pumice with pieces of lignite ve ace 296 soo | OROS) (7) Lapilli consolidated in patches ues abs apo) P20) 1 See Doelter, “ Carta geologica delle Isole Dae Pa Ve e Zannone,”’ Roma, 1876. —Memorie per servire alla descrizione della Carta Geologica d’ Italia, vol. iii. Parte 12, 1876. Dr. H. J. Johnston-Lavis—The Ponsa Islands. 53 (8) Brownish red dust bed uae ‘ 0°25 (9) Pumice bed decomposed at bottom 1-00 (10) Red ash bed . : ... 0°40 (11) Pumice bed. The pumice often compact from caleareous infiltration ... 1-10 (12) Stratified pumiceous dust, red at top : 0°65 (18) Slightly decomposed pumice bed... ; 0-90 (14) Finely stratified black dust graduating down into 0-60 (15) Pumice and lapillo ... 1-80 (16) Same, but with many fine ash bands ‘and more compact .. 0°60 (17) Grey pumice and lapillo ... 1-60 (18) Fine and coarse buff-grey stratified dust, With pumice at bottom. Itis compact, pisolitic, and concretionary . 4°80 iy Brownish earth, with scoria and pumice, a ey irregular bed ... 1-20 (20) Finely stratified greenish dust bo A ae id 1-60 (21) Pumice and lapilli, mostly fine 1-00 (22) Finely stratified buff dust ... aes 1°50 (23) Pumice and lapillo bed, fine, but more so above ... 1-00 (24) Stratified buff-grey dust, coarser in stripes with bits of pumice . 1-60 (25) Pumice-bed, with thin ash bands and finer in upper half 1:13 1-10 (26) Concretionary bed of ash... (27) Lava and scoria interealated in tufas at south-east angle of the island. Maximum height 56 ot apa (28) Red earth with pumice and small lava fragments... soc 006 (29) Band of decomposed pumice, finely bedded (80) Fine red earth with concretions (81) Pumice-bed with ash bands.. 20: (82) Breccia, ash dust, with pumice, banded, probably part 0 of last... (33) Pumiece-bed passing up into red dust at top be 000 (34) Red earthy breccia, stratified with scoria fragments (85) Doleritic lavas. (36) Stratified lapilli and dust, red at *oP, Beep marine ... So 3°00 (37) Brown and yellow scoria... 200 cot over 5-00 Sea-level It would be out of place here to go into all the details of each separate deposit. I shall therefore simply point out the general conclusions to which I have been led from their examination. The earliest deposits visible are brown, yellow, and red scoria, Japilli, and dust, presenting characters which indicate that they were basic essential ejectamenta from a cone in a state of activity, not unlike some of the more active phases of Vesuvius. This cone seems to have been situated somewhere west of the south end or perhaps west-north-west of the island, as this point shows the oldest deposits at the highest level, and represents parts of the slope of that cone. Also the valleys, if such they may be called, radiate from such a theoretical point. These deposits were followed by a great and continuous outflow of doleritic lavas forming the base of the southern prominence of the island. They have been studied microscopically and chemically by Doelter. A field study shows them to have been poured out almost continually without the intermission of extrusive action, as practically no fragmentary materials separate the different streams. In many places they show beautifully corded surfaces which would indicate their poverty in dissolved water at the time of their issue, the phenomena of which must have much resembled the eruption of 1858 at Vesuvius. The existence of the island depends upon the presence of these lavas extending below the surface of the sea, and wownwnodre aoe oS) a aS) 1S) >) 582 Dr. H. J. Johnston-Lavis—The Ponza Islands. resisting the powerful scirocco breakers. It seems to me that these lavas issued by some lateral fissure in the old cone, and piled them- selves up at this point, just as many of the eruptions of lava of Vesuvius may have been observed to do during the last ten years, just resembling in fact the guttering of a candle. The volcano then seems to have remained inactive for some time during the deposition of (384), but during that inactivity at the surface, the magma immediately below was gradually assimilating water, or in other words rising in elastic tension. This eventually overcame the overlying obstructions, and a series of explosive eruptions followed, interrupted by periods of repose (84-28). Whether these explosions drilled out a great crater or craters in the old cone, or were at some distance, is not possible of determination ; but it is not improbable that the ruin of the dolerite cone had been in part brought about. Bed (28) seems to show that repose did not follow the last of the explosions, but that the eruptive action continued, and as a con- sequence dwindled into a state of chronic activity, probably repairing in part or wholly, the old cone, during which time fine ash and lapilli, now red clay and lapilli, covered the surface (26). At any rate, a dyke forced its way to the surface, and gave rise to a small scoria cone, from which one or more lava streams poured forth. This scoria cone is seen on both sides of the island, and I give in Figs. 1 and 2 its relative position to the pumice-beds and the old lavas. Fig. 3 is a diagram showing how it is probably cut by the present cliff. Nn ent re. eo pel es Xe IN = = yay) sli fi a ~ Fic. 1.—Srction oF A Votcantc Conz And Turrs N.E. oF THE PIANO DEGLI OLIvE AT ISLAND OF VENTOTENE. 35. Submarine reefs of amygdaloid lava. 34-28. Pumice and other explosive eruptive products. 27. Doleritic scoria and lavas forming a small volcanic cone. x. Dyke which probably supplied same. 26-8. Upper pumice and other explosive eruptive products. 7-4. Compact tufa. 3-1. Vegetable soil, blown sand, etc. a, b. Sea-level. Dr. H. J. Fohnston-Lavis—The Ponza Islands. 7 533 _ Fie. 2.—Szcrton or Lavas, Turrs, Pumrices, AND A SMALL Votcanic Conn BETWEEN ‘‘It TELEGRAFO” AND THE “ TERRA ABBANDONTA,” VENTOTENE. a, 6, Sea-level. 37-36. Scoria, dust, ete. 39. Doleritic lavas (lower). 34-28. Lower pumices and other explosive eruptive products. 27. Doleritic (upper) scoria forming section of toe of small volcanic cone. 26-8, Upper pumices and other explosive eruptive products.. d Fig. 8.—DIAGRAM OF THE SECTIONS OF A VOLCANIC CoNE SEEN IN CLIFFS OF VENTOTENE. a. Toe; 6. rim ande. vent ; . and y. parts removed; d, d. North-west and ¢, e. S.E- coast-lines. With (25) recommenced a series of explosive eruptions (25-8), which culminated in a gigantic one represented by the different pumices, scoriaceous pumices and tuffs (7-4). Of course it is impossible to say at what point all these pumice and dust deposits were erupted, and it is not improbable that they were derived from different eruptive centres. The last seems to have been very near 5384: Dr. H. J. Johnston-Lavis—The Ponsa Islands. at hand, for at Ventotene it attains a thickness of 10 m. or more and is distinctly if at all represented at Santo Stefano. It is probably by this eruption that the greatest destruction was wrought in the old cone, and that the crater apex extended down into the subjacent metamorphosed rocks. In fact, the explosive products at Santo Stefano are generally smaller and finer than at Ventotene, and seem therefore to have been derived from a centre or centres nearer the latter island. A grave error has crept into Prof. Judd’s “ Volcanoes,” where the lavas are represented as a stratum covering the tuffs of the island, instead of the reverse. These different pumice deposits are chiefly derived from a basic magma, probably having the same composition as the doleritic lavas of the island. Of far greater interest from a physical point of view is the regular sequence of the different ejectamenta in each explosive eruption, which I first pointed out at Vesuvius, and have confirmed in a very large number of volcanic deposits. In each we find comparatively vitreous pumice at the bottom followed by micro- crystalline pumice or scoriaceous pumice, and finally a dust bed. Whilst the divisions show a rapid increase of extratelluric ‘‘ formed material ” as the eruption progressed, the intratelluric minerals have not increased in number, the whole confirming the conclusion that the hydration of the igneous magma was limited to near the earth’s surface.” The blown sand already mentioned consisted of a mixture of augite and other mineral grains with shell fragments and foraminifera. It must have been carried up on the slopes of the island by the wind from an old beach probably formed on the extensions of the last great tuff deposit, but now cut away. By percolation of carbonated waters, nearly all the subjacent rocks have been permeated and often cemented together or filled by calcareous concretions. We find the lavas near the sea-level also become amygdaloidal by the presence of tufts of aragonite crystals in the vesicles. Very interesting is the presence of irregular compact white amorphous concretions, often attaining a weight of 50 or more - grammes, and composed of almost pure magnesite. These are included in and between the masses of scoria of the buried cone of eruption. They are probably due to emanations at and subsequent to the eruption. I have noticed very similar ones in a vesicular doleritic lava of the east coast of Vulcano. The next point to which I wish to draw the attention of geologists is the remarkable evidence of elevation to be seen in the island of Palmarola, which seems to have escaped the notice of recent visitors. In the middle of the island is a depression somewhat in the form of an amphitheatre, open to the west and shelving down to the small ' The quantity of these explosive ejectamenta is such that the scoria cone was entirely buried in them, so that its existence is only known by the exposures in the cliff sections. See Figs. 1 and 2. * Q.J.G.8. 1884 and Proc. R. Dublin Soc. vol. v. July, 1886; Proc. Geol. Assoc. vol, ix. Dr, E. Nawmann—Magnetism and Earth Structure. 535 beach. -On the east coast this depression is, so far as my memory goes, at least seven metres high, and lies to the side of the Forcina dyke. It seems dependent upon the clay through which the dyke was injected being easily subject to erosion. This deposit looks much like a Pliocene clay, but my hurried and forced departure from the island prevented me from more fully investigating it, as also the actual height above sea-level of the lowest edge of the breach. Dolomieu, who visited the Ponza Islands in March of 1786,! says: “Cette Ile (Palmarole) est divisée en deux parties presque égales par un canal étroit qui la traverse vers la moitié de sa longueur, et dans lequel on passe en barque.” Besides this clear statement he gives a map of the island showing the canal in the position of the amphitheatre depression, and the lowest breach in the east coast-line. At present the lowest part of this depression I noticed strewed with boulders covered with Serpule and other marine growths, looking quite fresh, but above sea-level. We have evidence here of a very striking kind, of a very considerable elevation during a period of little less than a century—as important I believe as any recorded. I regret that I did not make more detailed observations, but the un- fortunate circumstances which caused my departure, together with the fact that it was only after my return that on looking at Dolomieu’s map, the fact struck me. I hope, however, to carefully investigate the matter next summer, so as to make public such an important piece of geodynamical evidence. Of course we have other prehistoric evidences of elevation in abundance in these islands, and one in particular that struck me, namely, the occurrence of beds of well- rounded pebbles half-way up the cliff of Monte della Guardia at Ponza. But the elevation of an island from 5 to 10 metres or more in a century would be of inestimable value as a cardinal fact in geology, if fully confirmed. I].—Terrrestriat Magnetism as Mopirrep BY THE STRUCTURE OF THE Harru’s Crust, anD Proposats Concernine 4 MAGNETIC SURVEY OF THE GLOBE. By Dr. Epmunp NauMANN. ; (Concluded from the November Number, p. 490.) [PLATES XV.-X1X.] | WILL now put forward some details, for it seems necessary that some proofs of what has been maintained in general should be given, and 1 shall therefore quote some examples of the intimate connexion between earth-structure and terrestrial magnetism. No diagrams could indicate the relations better than Locke’s Magnetic Sections across the Hudson, which were taken at three different points of the Palisades, Snake Hill, Fort Lee and Patterson (see Plate XV.). The dip and intensity were in each case determined at a number of points along a line perpendicular to the range of cliffs, 1 Jles Ponces, 1788, p. 128. 536 Dr. E. Naumann—WVagnetism and Earth Structure. and the curves rise very suddenly to maxima just above the edges of the cliffs, which are composed of columnar diorite. This diorite is widely distributed and lies between masses of Triassic sandstone ; the dip is slight and towards the west. On the east side of the cliffs Laurentian gneisses are exposed. The close proximity of formations so far apart in age must be caused by a great fault, and the perpendi- cular dislocation amounts at least to some thousands of feet. In Locke’s opinion the very sudden rise and fall of the magnetic curves are due to the columns of diorite being magnetized by terrestrial induction, but I think there can be no doubt that the great fissure is the chief cause of the sudden changes. Another beautiful example is afforded by Nipher’s “ Magnetic Survey of the State of Missouri.”* The isogonic line of 7° 30! describes a loop, in the centre of which lies the Pilot Knob, a hill 662 ft. high, and composed of porphyry, porphyry conglomerate, and layers of hard red sandstone. To the east is the knob connected with other porphyry hills. If we remember that the Pilot Knob can be nothing but an old volcano, whose subterranean core passes to great depths, we can well imagine how the hearthlike eruption may deflect electric currents from their direct track, and cause irregu- larities in the magnetic elements. Marvellous coincidences between magnetic curves and lines of great geological disturbance are met with in Asia. It seems as if the Himalayan range exerted some controlling influence over the isogonic lines; some of these follow the direction of the mountain chains, and the way in which the 2° 30’ and 38° curves go high up the Brahmaputra valley and then turn back to the S.W. is very striking (see Plate XVI.). Rijckevorsel, the well- known surveyor of the Indian Archipelago, speaking on this subject, says, that “It is as if the land had some power of coercion over the isogonic lines.”? J venture to submit that it is not the _ land which exerts this influence, but the great longitudinal ruptures indicated by the submerged mountain range. It may be that in a great portion of Asia the isogones coincide with lines of great geological displacement. Another illustration in support of our theory may be taken in Europe. The district between the Carpathian Mountains and the Transylvanian “ Erzgebirge” forms an almost circular basin; this region was surveyed by Kreil about forty years ago, and by Schenzel in 1875-76. During the interval the isogones have (of course) changed their position, but still the two maps, one for the period ' Nipher, F., Magnetic Survey of Missouri. Fifth Annual Report, Trans. St. Louis Ac., vol. iv. No. 8, p. 516. Chart of the Magnetic Variation in Missouri, St. Louis, 1880. Sold at Robert Beneck’s, St. Louis. Chart of the Magnetic Variation in Missouri (photograph of a plaster chart), St. Louis, 1881. ? Rijckevorsel, Report to His Excellency the Minister of the Colonies on a Megnee Survey of the Indian Archipelago, made in the years 1874-1877. Amster- am, 1879. $ Schenzel, Beitrage zur Kenntniss der magnetischen Verhaltnisse im Sudostlichen Ungarn, Repert. f. Experimental Physik, f. physikal Technik, f. math. u. astron. Instrumentenkunde, Herausgeg. vy. Carl, Miinchen, 1877, Bd. XIII. s. 165. Dr. E. Naumann—NMagnetism and Earth Structure. 537 of Kreil’s observation, the other for the later epoch, show a most remarkable similarity. To the east, the isogonic lines are parallel to the Carpathians, and they turn round near Kronstadt and Fogarasch, just as the Transylvanian Alps do. The centre of Tran- sylvania is traversed by a loop. We thus see that the isogones present a thoroughly natural form, and that their characteristic features remain unaltered, notwithstanding the secular changes of magnetism. This is certainly a very important result. A considerable number of other illustrations might be quoted, but I am afraid of digressing too far, and must refer those who take a special interest in the matter to the above-mentioned paper, in which a discussion of all the magnetic surveys hitherto accomplished will be found. Many pages of it are devoted to the results of the _ Magnetic and Geological Survey of Japan, carried out under my direction during the years 1880-85. Those results are of special importance to our subject, and I may therefore be allowed to submit some observations which have come under my own experience. There is a most remarkable correspondence between the lines of equal declination and the principal lines of geological structure. In general the magnetic lines exhibit striking and unexpected irregularities, and these irregularities are found to be most intimately connected with the abnormal curvatures of the folds. The serious discussion which followed the reading of a paper of mine before the Seismological Society of Japan in 1882! showed how far these irregularities were unexpected. For my own part I was convinced from the very beginning of the Geological Survey, at a time when the magnetic data were still scanty, that there must be some connection between the phenomena caused by terrestrial magnetic force and the internal condition of the earth’s crust or of the earth itself. With this point in view the magnetic investigations were commenced. In a comparatively short time the general magnetic survey, com- prising no less than 200 complete observations at a like number of stations, was accomplished by Mr. Sekino, one of my former topographical assistants. The results are very satisfactory. It will be observed that the course of magnetic lines are influenced by the great transverse cleft called Fossa Magna (see Plate XIX.). This is a great depression, cleft, or fissure, running from the Pacific to the Japan Sea, in which a number of volcanoes have sprung up. Fujinoyame, for instance, the highest mountain of the Japanese Archipelago, is situated in this cross fissure. The Japanese chain consists of a long series of folds, running as a rule in the same direction as the island chain itself, but in the neighbourhood of the Fossa Magna these folds (which were probably raised by a force acting from the continent towards the Pacific) turn back as if they had been stopped by the great wedge of eruptive rocks lying below the Fossa Magna. In Mr. Sekino’s Magnetic Map (Plates XVIII. and XTX.) the 5° isogone will be seen to cireumscribe the Fossa Magna, for in that vicinity the curve forms a great wave whose crest is upturned ' Notes on Secular Changes of Magnetic Declination in Japan, vol. v. of the Trans, Seism. Soc. of Japan. 588 Dr. E. Naumann—Magnetism and Earth Structure. towards the Japan Sea. This curve, therefore, exhibits the same features as the axial line of the folds, and to a certain extent the isogones and the fold lines coincide. In a paper published in the Proceedings of the Royal Geographical Society,! containing a some- what fuller account of the geology of Japan and of the distribution of magnetism in that country, I have said: “These results open out an entirely new field of research, and I hope that they may be an inducement to a continuation of similar investigations, so that some light may be thrown upon those still very obscure pages relating to the causes of magnetism and to the internal condition of the earth.” Since the publication of the above-mentioned memoir, letters of approval have been received from many well-known authorities, and a number of reviews, by no means unfavourable, have appeared. But in some cases I have been entirely misunderstood, and quite recently a violent attack has been made by Dr. Cargill G. Knott, of Tokio He says, that an inspection of the results of Sekino’s survey, carried out under my direction, convinced him that it would be unsafe to deduce from them any definite conclusion as to the general magnetic characteristics of Japan, and to him it appeared “that the thing to be desired was a new survey, which might be called a preliminary survey of all Japan.” These remarks tend to depreciate Mr. Sekino’s observations, and are accompanied by several unfounded accusations. The latter I hope to prove unjustified by stating a number of facts, and as evidence that Mr. Sekino’s survey is not to be despised, I have prepared several maps as follows: Plate XVIII. is a combination of Mr. Sekino’s and Dr. Knott’s maps, from which it will be seen that there is no essential difference between the lines obtained by the two observers. If they do not exactly coincide, it must be borne in mind that the two maps relate to different epochs (Sekino, 1882-83; Knott, 1887), separated by four or five years. In discussing the question of secular change, Dr. Knott ignores the fact that the rate of change varies with time and locality, hence his method of comparison is unsatisfactory, and average differences are not allowed. Apart from adverse statements, I do not hesitate to welcome Dr. Knott’s work, for his map is a good check on Mr. Sekino’s observations, and shows that Sekino’s — survey can stand as a Preliminary Survey of Japan. Plate XVII. is a combination of Dr. Knott’s map with my Tectonic Map of Japan. Speaking of his own map Dr. Knott says that ‘‘two regions are to be noted as presenting magnetic irregularities; one is the great mountainous region about the Fossa Magna, and the other is between the 38th and 40th parallels. I quite agree with Dr. Knott even as regards the irregularities of Northern Honsbin. They are mentioned in my paper on the Geology of Japan, in which I 1 The Physical Geography of Japan, Proc.R.G.S. Feb. 1887. 2 Cargill G. Knott, D.Sc. (Edin.), F.R.S.E., Professor and Aikitsu Tanakadate Professor of Physics, Imp. University of Japan, A Magnetic Survey of all Japan, carried out by Order of the President of the Imp. University, Journal of the College of Science, Imp, University Japan, vol. ii. part iii. Tokio, 1888. Dr, E. Nawmann—Magnetism and Earth Structure. 589 make the following remarks: A kind of break of the isogone occurs between Sado and Sendai. This must be of special interest, as a geological dislocation line runs across Japan in this region. The irregularities are also referred to in a later pamphlet on magnetism. As regards Dr. Knott’s curves—although some details of declination may be questioned—I think they are a sufficient proof that the distri- bution of magnetism bears some relation to the great lines of geological structure.* When I undertook the Geological Survey of Japan, of which the magnetic survey was part, the steps taken were guided by previous experience. The bulk of mariner’s observations were gone through, and Ino’s. field books and maps consulted for compass-measurements. These studies enabled me to select the stations at which Mr. Sekino’s observations were subsequently taken, in accordance with a definite scheme. The Sado sinuation is roughly indicated on a small map published in 1882, and from my magneto-tectonic map (Plate X1X.) it will be seen that the selected stations keep fairly close to the ascertained magnetic curves. These facts are sufficient to show that the arrangement of stations was made with the utmost care. I am afraid that Dr. Knott’s stations were not distributed so judiciously. It is greatly to be regretted that the second magnetic survey of Japan was carried out so independently, and without the valuable hints which might have been derived from previous investigations. Not even the field books of the Geological Survey were consulted. These books contain sketches by which the exact position of every station can be easily determined, and in accordance with the practice of Lamont the topographical data necessary for the redetermination of the places of observation were ascertained, in order that future observers might work on the same spots. From the memoir on the second Magnetic Survey of all Japan we learn that of the 81 stations taken 27 can be regarded as coincident with stations of the previous survey. A few of these are only roughly coincident. I should digress too far by stating fully the reasons why I determined that the stations should be on the route followed by Messrs. Sekino and Kodari; it is sufficient to say ~ that the test offered by the second Magnetic Survey justifies their distribution. At the same time, I cannot avoid stating that the new observers should have felt it their duty to devote special at- tention to the most interesting regions about the Fossa Magna, and between Sado and Sendai. Dr. Knott considers it very important to fairly distribute the stations over the whole country, and that it is necessary “‘to give volcanoes a wide berth, as these have been shown by previous observers to be a great source of disturbance, 1 There is something very striking in Dr. Knott’s representation. The centre of the great loop of 4° 20’, which will be noticed in the main island, coincides with the intersection of the great longitudinal and transverse fissures (Fossa Magna) of Japan. His curve of equal total force, and that of equal horizontal force, also prove that the Fossa Magna has some influence on the magnetic curves. 540 Dr. FE. Naumann—WMagnetism and Earth Structure. especially as regards the declination.” ‘Then, almost in the same breath, he searches for the causes of observed irregularities, and finds them in the distribution of volcanic rocks. Little or no attention seems to have been paid to the most interesting dis- turbance that must have existed at Ino’s time (at the beginning of this century), and which Mr. Sekino’s observations show to still exist, nor was the peculiar phenomenon exhibited by the magnetic block on the summit Morigoski examined; this is all the more surprising, as two stations of Dr. Knott’s survey lie in the immediate neighbourhood of these remarkable places. It may appear that I am dealing too minutely with Dr. Knuott’s paper, but I think the criticisms are justified by the interests of science. It is by no means satisfactory to see that so many fellow- workers on the field of science cannot build without pulling down, for it should be the serious duty of every one to advance from wherever a safe footing has been attained. Earnest and honest labour deserves respect rather than condemnation. Unfortunately it is usual for critics to introduce their subject with an exhaustive survey of all its faults, instead of commending its merits. The greater the effort made to ascertain its merits and appreciate them, the easier will it be to use existing knowledge as a foundation for future progress, and those who neglect this duty tend to check rather than promote the advancement of science. Dr. Knott does not appear to be acquainted with my pamphlet, for if he had read it he need not have devoted so many pages to the rather antiquated chapter on Rock Magnetism ; and if his knowledge of the Geology of Japan was more profound, his opinion as to the causes of irregularities being entirely superficial would be modified. In his paper we are taught that “the volcanic nature of the rocks is more than enough to account for all irregularities.’ Why ? Perhaps because volcanic rocks are known to contain magnetic iron ore? If so, Dr. Knott should have remembered that the volcanic tuffs, widely distributed over the country, consist of the same materials as so-called volcanic rocks. In addition, as proved in my memoir, rock magnetism does not influence the curve-systems, nor do the values of the constants depend on the nature of the rocks developed in the neighbourhood. In considering such questions the following points are important : how the earth’s crust is composed of masses of rocks; how deep the fissures penetrate into the earth and establish connection with the interior of the globe; whether these fissures are closed or not, ete. In the locality under discussion there are two enormous fissures, intimately connected with the development of the great earth-wave whose crest appears as the Japanese island chain. One of these is longitudinal, and divides the whole mountain-range into inner and outer zones ; the other is transversal, and divides the chain into two parts which stretch towards the north-north-east and west-south- west respectively. The transversal fissure is indicated by the Fossa Magna, and the longitudinal one curves back towards the Sea of Japan, where it intersects the former (see Plate XVII.). Enormous Dr. E. Naumann—Wagnetism and Earth Structure. 541 masses of molten matter have been ejected from these clefts, and it is not difficult to imagine that such enormous fissures have some influence upon earth currents, and consequently on the magnetic needle. My former remarks on the reduction of the declination values to one hour are said to contain a “slight” inaccuracy, and Dr. Knott seems to think that no correction was applied to observations made at the northern stations. On this supposition he depreciates Sekino’s observations, and, together with the supposed injudicious distribution of stations, it is used as an argument against the first Magnetic Survey. The title of Sekino’s Magnetic Map of Japan, which was exhibited at the Berlin International Congress of Geologists, and now belongs to the Geographical Society of Berlin, runs as follows, ‘‘On trouve les valeurs actuelles des observations indiquées pres des stations par les mémes coulers que les coleurs correspondantes. Les observa- tions sur la declinaison seulement sont réduites en moyenne diurne.” Before publishing my pamphlet on magnetism I wrote to Sekino asking him to give me the exact times at which each observation was taken, and he replied that the values in the list I kept were daily means. I am certain that before leaving Japan I gave instructions for a reduction of all declinations to be made, and hitherto I was convinced that this had been done, although the reduction for the northern stations could only be approximate. If Dr. Knott has any doubts about the matter, he may readily remove them by inspecting Sekino’s field books, for, as stated above, these books were not written to be buried in the Archives of the Geological Survey, but were prepared for the use of future observers. There are, I think, very few persons who have a good idea of the surface configuration of the earth, even where only a small part is concerned. In most cases heights are exaggerated in memory, and consequently the angles of inclination are taken far too great. How insignificant is the depth of the deepest part of the ocean when compared with the dimensions of the globe as a whole! Lamont has tested the question as to whether there is any change in the magnetic elements due to differences of level, and the results show the change to be imperceptible even for considerable differences of height. From this he concluded that the seat of terrestrial magnetism is not to be sought near the surface, but at enormous depths below the surface. I may here be allowed to draw attention to a most interesting theory of Lamont. He admitted the frequent occurrence of irregu- larities in the systems of magnetic curves, and attributed them, not to the influence of magnetic masses contained in the crust, but to elevations and depressions, i.e. to irregularities, of the earth’s nucleus. His opinion may best be stated in his own words: “'The magnetic curves represent the surface of the nucleus.” If Dr. Knott had been well acquainted with these remote but classical investigations, he might have omitted the discussion of results given on page 214 of his Memoir. In my pamphlet on Magnetism I have given a fairly complete 542 =Dr. E. Naumann—WNagnetism and Earth Structure. list of the most important works on the subject, and I consider it necessary that every scientific investigator should have a profound knowledge of the literature of his subject ; for when so qualified he need not discuss works which he has not studied carefully. Amongst the works which I have had occasion to peruse during my studies in terrestrial magnetism, a memoir by C. A. Schott on the secular variation of magnetic declination in the United States and at some foreign stations, is of special interest. Any one who has devoted any attention to the subject of secular change, knows that it is one of the most complicated branches of terrestrial physics, and at first sight it seems very curious that by far the greater number of copies of the above memoir were sold to lawyers. The demand in law circles for the work which treated of a purely scientific subject was so great, that several new editions had to be issued; and the reason of this is to be found in the difficulties experienced in following the old boundary lines of landed property, which had been originally laid out by the magnetic compass. This case is a good example of how a purely scientific problem may suddenly and unexpectedly become one of great practical importance. Schott’s investigations tend to show that the secular variation is periodic, but unfortunately the observations do not extend over a complete cycle. He compares the secular change with the motion of a pendulum. In the United States south of the 49th parallel, a complete cycle requires 24 to 34 centuries, and during this interval the needle describes arcs varying from 3° to 7°; in Paris the ampli- tude is 38° and the period about 42 centuries. Taken as a whole, the secular variation is perfectly systematic, and subject to remarkable laws which will well repay careful study, and being a phase in the life-history of our planet, the secular change may prove an excellent means of comprehending the internal condition of the globe. In Japan the magnetic elements have undergone considerable changes since the beginning of the present century, as may be seen by comparing recent surveys with that of Ino Tadagoski; a Japanese astronomer, who, about that period, made a geodetic survey of his native country. This observer had heard and read in foreign books of the variation of the compass, but, nevertheless, he denied its existence, and even went so far as to attribute the declination observed by Europeans to errors in their compasses; he also main- tained that the fact of his own needles always pointing due north, was owing to the superiority of his instruments, which were of his own construction. Thus he was led to believe that no variation of the compass existed. The average amount of secular change during the interval 1800 to 1880 is between 3 and 4 minutes of are per annum. Dr. Knott maintains that at the present time there is no secular change in Japan, and if this be correct, it is an important and unexpected result. Let us see how far it may be relied upon. As stated above, Dr. Knott uses a method which is a contradictio in adjecto, for if an average of differences be taken, and this average proves to be zero, as in the case considered, it does not necessarily Dr. E. Nauwmann— Magnetism and Earth Structure. 548 follow that there is no secular variation in Japan, but the result can be explained by the well-known fact that the amount of secular change is different in different places, and may be positive in some, whilst it is negative in others. From a comparison of Sekino’s and Knott’s maps, however, it may be seen that the isogonic lines have shifted very little indeed, and we agree with Dr. Knott when he says: “‘ Within the period beginning with 1883 and ending 1887, there is practically no change, or if there is, it is a very small change indeed. It looks almost as if we were just passing through a time of maximum declination.” This result is extremely interesting if we take into account what Fritsche has said about the line of zero declination when it passes through Mongolia. The value of the secular varia- tion for stations lying near this part of the line is very small, and we may therefore conclude that the wnole magnetic island of western declination covering a considerable part of Hastern Asia is at present in a nearly stationary condition. When speaking of the diurnal means obtained from Sekino’s survey, I quoted part of the explanation accompanying his magnetic map, and I now direct attention to another passage of that explana- tion, which runs as follows: “Il y a un nombre d'irrégularités considérables qui sont particuliéres & des régions isolées. Ce ne’st pas le caractére spécial de ces irrégularités qui est représenté dans ja carte par les lignes en forme de cercle, mais simplement le lieu et Vextension.” There is no doubt but that a complete magnetic survey of Japan will prove the existence of many small magnetic islands, which can at present only be vaguely indicated. Dr. Knott’s map does not show the Sado sinuation of the south- west curve as I have shown it, but represents the irregularity by an isolated line round the island. He prefers this form because— as he says—it is well known that the isogonic lines at or near islands often present irregularities of quite a local character. I am inclined to believe that this is not well known. I, at least, was not aware of it, except as regards oceanic islands which may —as Rijckevorsel says—appear to have some power of coercion on the isogonic lines. Oceanic islands, however, are indications of great submarine mountain ranges, which are generally accompanied by deep fissures in the earth’s crust, but no power of coercion can be expected from an island which is merely a detached piece of the main land. The problems presented by the magnetic islands of Japan can only be solved by a very detailed survey, and it is interesting to enquire what such a survey means. (Quite recently a very detailed magnetic survey of part of the kingdom of Wiirtemberg has been carried out by Hammer, and he estimates that about 90 stations would be necessary for the whole kingdom. ‘Taking this as a basis, Japan would need 1800 stations, Germany 2500, and Great Britain 1500 stations. These numbers induce me to again refer to the distribution of stations in the first Japanese survey, objected to by Dr. Knott. In 544 Dr. E. Naumann—WMagnetism and Earth Structure. his survey observations were taken at 80 stations, and in the first survey 200 stations were selected. When compared with the requirements of a detailed scheme, both these numbers appear very modest. In such cases it is all the more necessary to distribute the stations judiciously instead of merely spreading them “fairly over the whole country,” for it is only exhaustive surveys which can adopt the latter principle advocated by Dr. Knott. Similar remarks may apply in orographic surveys, for a reconnaissance requires quite a different distribution of stations to that needed for an elaborate undertaking in which time and money are not important. Having had some experience in reconnaissance surveying, I am well aware how carefully the stations must be selected. The above numbers also give us an idea how very far we still are from having accomplished detailed magnetic surveys even of parts of the earth’s surface; it is only in a few very limited districts in Missouri, Transylvania and Wuirtemberg that such surveys have been attempted. The whole question needs to be taken up inter- nationally, and I trust that these lines may convince my readers of the great importance of the subject. Rich harvests may be expected from a field which can only be explored by the joint efforts of all the workers in this great cause, and the stimulus imparted by British scientists will be sure to find a ready response on the continent. To many sciences the problem of terrestrial magnetism is the common focus, for physicists, geographers, topographers, meteorolo- gists, astronomers, etc., and above all geologists, must be interested in it. In former times magnetic observations were commonly attached to astronomical ones, and astronomers were in charge of the observations, whilst at present the subject forms a branch of physiography, and the observatories are usually connected with meteorological establishments. The latter arrangement seems to be the most satisfactory one, and great interest is taken in the question by meteorological societies and offices on the continent, particularly at Hamburg, Berlin, Vienna and Munich. To come to the practical side of the question, I beg to propose that an International Congress be held, say in London, at or about the time of the next British Association meeting. This Congress might decide numerous questions, still unsettled in the minds of the majority of observers, and may pass resolutions prescribing uniform schemes on which magnetic surveys should be carried out. It should also endeavour to induce the various Governments to take an active part in promoting the magnetic survey of their respective countries. Dr. Naumann’s paper is illustrated by Plates XV.—XIX. Plate XV. Locke’s Magnetic Sections; Palisades of the Hudson and Patterson, New Jersey. Plate XVI. Magnetic Curves of the Himalayas. Plate XVII. Tectonic Map of Japan with Dr. Knott’s Magnetic Curves. Plate XVIII. Comparative Diagram of Mr. Sekino’s and Dr. Knott’s Magnetic Curves of Japan. Plate XIX. Magnetic Tectonic Chart of Japan by Dr. KE. Naumann. Dr. F. H. Hatch—L, Silurian Felsites of 8.H. Ireland. 545 II].—On toe Lower Sizturtan Fetsitrs or tHe Souts-Hast oF IRELAND.! By Freperick H. Hatcu, Pu.D., F.G.8. (Communicated by permission of the Director-General of the Geological Survey.) HE felsites of the south-east of Ireland are shown on the maps of the Geological Survey? to extend over considerable areas in counties Wicklow, Wexford and Waterford. Like the Welsh felsites they are contemporaneous with Lower Silurian (Ordovician) strata, and were probably erupted on an old sea-bottom. 'They are accom- panied by abundant deposits of tuffs and breccias, the component ‘fragments of which consist mainly of felsite. A chemical examination of one of the felsites, made when I was preparing a petrographical description of the more important igneous rocks for a memoir on Sheets 138 and 1389 of the Irish Geological Survey, showed it to be asoda-felsite ;* and this discovery induced me to make a more extended examination of these felsites. A number of specimens from different localities were collected and sliced; and a chemical analysis of those that promised interesting results was kindly undertaken by Mr. J. Hort Player (to whom I here tender my best thanks). The object of this paper is to communicate these results and to discuss them in connection with the microscopic characters of the rocks. The main point brought out by chemical analysis is the almost entire absence of lime, and the presence of potash and soda in varying proportions : in other words, the lime-soda series of felspars is unrepresented in these rocks, which must therefore contain either a varying proportion of potash-felspar (orthoclase) and soda-felspar (albite) or one or more felspars of a potash-soda series (anorthoclase). According to the relative proportion of potash and soda the rocks are roughly separable into the three following groups: (1.) Those in which there is a large excess of potash over soda, the latter being present only in small quantity. These may be termed potash-felsites. (1I.) Those in which the soda, though present in considerable quantity, is yet subordinate to the potash. These may be termed potash-soda-felsites. (1II.) Those in which the soda is in excess. These may be termed soda-felsites.* 1 Read at the Newcastle Meeting of the British Association, Sept. 13th, 1889. 2 Sheets 180, 189, 148, 149, 158, 167, 168, 169, 178, and 179. 3 Grou. Mac. 1889, p. 70. 4 Should the soda be i a “but slight excess of the potash, the rock might be termed a soda-potash-felsite. The term keratophyre (originally suggested by Giimbel) has been applied by Lossen to a rather indefinite group aleve includes rocks similar in character to those in Group III. The term soda-felsite appears more applicable to these rocks. DECADE III.—yYOL. VI.—NO. XII. 30 546 Dr. F. H. Hatch—L. Silurian Felsites of SE. Ireland. eal I. (Potash-felsites. / 5) (lo RNB) Dy (Ql i572.) 3. (I rros)) "4-5 SiO, PUT ORG RAL Rs iil Ones 266-28 aaa 85:2 Al,O3 TOM e si aone NASD Biiacescees 136i ogee. ce: Fe203 MOM redeasieee Siatgdeseas GG} Pcossedcoa b) FeO HOM eaecoete Gy itaaecaaaneD BG) ei csmenae 4 CaO ODA Seagonas8o trace ......... trace. Si cssanee trace MgO Teale aU ae Tele teak ae 1:8. cea 4 ROOM Awe ceek arch egacn oleae) SOME mise tiie BG nodosenes (GM ene eA con 4:4 Nid OF cere Sti hactaavenees Cod cea aan io eracerasr Slt wtatnicaieae HD Ag asieteieteiaeae °8) Loss on ignition Sane cher TOY Mosaic SY Be Aree ei ar Oe eaawemeine 6 Total ec(iscey -sne POOre 99°6 100°1 99°8 S05 (Elo aga. 0g 050 PEDO 2606 2°619 2°622 Orthoclase percentage! ... 54°2 ......... Oe MEercases ACL ga eae 26-2 Albite percentage ... ... OM bedes OADM sabae #8) Ti eee 76 Group II. Gel soda-felsites.)? 5. (1. 81.) 6. (I. 126.) 7. (I. 169.) 8. (I. 109.) SiO ae pet ass owas cscwen foseet a) COMO he seks TAPS recess (GSS) per scscnor 73°6 AleOs . 30 MOL Oi es ech ee BQ Soane aco WPS) coscakoae 13°8 Fe203; . (isoretor ven ORM cree = unseen 5 HeOwe Tae Na ce HAD) ise noBdons 1000 ec » 24 CaO . BORO Di ak WENO) | Sondecaen Ihe eoaHbaahsc 6 MgO . aOa tea Ter ae A \yehaeeee 7 K,0 ig eaenonaae Oy Gem ceeaunrise Bs Gel eee 4°3 INTER OS sare Prato ohno masa aclenaoiate 7 arasenceee: DION RAS ANAS GE BO aiseeete 3°2 Loss on ignition... B40 ja60 ROM ceiseeissis Ie deep adobe D9 Nomeaners 6 Motale avec tel asec e rate | QOSG MeL sein OKO 238 eladaodorc 99; Sik! eee 99°7 SP oueentccesa ah scnO4 Oueiieianians ABOD sodooseac BABVAD seaccaoen 2°658 Orthoclase percentage ... 386°4 ......... Soc OAC erent 33°31 Pence 25°7 Allbiteypercentage 55.) 1-2.) 28:81) tees. IRSA) acasaads 2OCA eae 27-1 Ce III. (Soda-felsites.) (I. 83: ) 10. ° 805) ll Ge aie ) 12. (I. 96.) Si0, ae See senns Wo rar tiecels TIES. enna 71°6 Al.V3 a boossdo0n nee poonddiod TOD) eras 16°9 Fe,O3 . BU Yale sae oe CuaaCAlsd Qh aes eee 3 FeO DOE Nits. str ASO). teshee eee doe Veeyaeoee ) CaO 0) eae 8h) yaaa WENGE) Sonscosoe 2°2 MgO PIE Bodtooee *@) coanocese (HENS) copesncce 6 K,0 DOS DeOye i ee DTN eas 13 Na.O BA Wisbee Wee BoD niskieaictn EE ( RaRURB ANSE Ory isiecaess 4°7 Loss on ignition .. SPS eral hid We ar SOM e se tise AB Seocosoge 1-1 Total ee uiancetnl pe sen OOS 100°2 OB)7/ 99°6 (yOu Ch! oda? lacdy! ooo AROOY 2°606 2°634 2°607 Orthoclase percentage ... 13:0 LIL) 12°5 8°5 Albite percentage ... ... 30°6 39°9 43°2 39°9 1 The whole of the potash has been calculated as orthoclase from the formula K,0. Al,O3. (Si0),; and the soda as albite from the formula Na,.O. Al,03. (SiQ.)¢. 2 See also three analyses of felsites from the counties of Wicklow, Wexford, and Watertord by the Rev. 8. Haughton (Trans. Roy. Irish Acad. vol. xxiii. part li. 1859, p. 615). 3 See also two analyses of soda-felsites from the Waterford coast by the late J. A. Phillips (Phil. Mag. 1870, vol. xxxix. p. 12; Gon. Mac. June, 1889, p. 288), and an analysis of a Wicklow soda-felsite by the ‘author (Gzou. Mag. Feb. 1889, p. 70). Dr. F. H. Hateh—L. Silurian Felsites of SE. Ireland. 547 Notes on the foregoing Groups. Group I.—1. (I. 113.)—Half a mile south-east of Cairn on Castletimon Hill, Co. Wicklow. Sheet 130. 7 Compact grey felsite, of irregular fracture. Under the microscope shows felsitic (cryptocrystalline) structure, but with frequent patches of more coarsely crystalline (microcrystalline) matter. No porphyritic crystals. 2. (I. 172.)—One mile west of Great Newtown Head, Co. Waterford. Sheet 179. Compact brown felsite, of irregular fracture. Under the microscope shows a cloudy unindividualized substance, containing a number of ill-defined spherular clots, mostly aggregated in strings. These bodies have no radially fibrous structure, presenting between crossed Nicols a speckled or dappled depolarization instead of the character- istic black cross, and cannot therefore be regarded as true spherulites. They doubt- less represent, however, some incipient form of crystallization. The remainder of the ground-mass shows a confused, patchy deyitrification, The rock contains no crystals and is probably a devitrified pitchstone, 3. (I. 110.) —Castletimon-ford, right bank, Co. Wicklow. Sheet 130. _ ‘ Compact, grey, mottled felsite, fracturing easily; the joint-faces stained with oxide of iron. Felsitic or cryptocrystalline structure with an occasional porphyritic crystal of non-striated felspar (orthoclase). Between crossed Nicols the devitrification of the ground-mass shows itself in the presence of innumerable minute spherular bodies, each giving a black cross. Chlorite is present in scattered scales. 4. (I. 111.)—Castletimon-ford, left bank, Co. Wicklow. Sheet 139. Very compact, light grey felsite; brittle and splintery, fracturing easily along joints, the faces of which are stained yellow with oxide of iron, resulting from the decomposition of pyrites which occurs in small quantities in this rock. Under the microscope the structure is truly felsitic or eryptocrystalline, there being no porphyritic crystals present. Group II.—5. (I. 81.)—Quarry on road from Woodenbridge to Aughrim, 14 mile north-west of Woodenbridge, Co. Wicklow. Sheet 139. Compact grey felsite, spotted white with small crystals of felspar. Iron pyrites in disseminated specks. Under the microscope: Cryptocrystalline ground-mass, embedding numerous por- phyritic crystals of striated felspar. The twinning is on both types (pericline and albite). Microperthite structure is occasionally shown. 6. (I. 126.)—Kilmacrea Wood, 12 mile north-west of Redcross, Co. Wicklow. Sheet 130. - Compact, grey, mottled felsite. Under the microscope: Structure varying between cryptocrystalline, in which the constituent granules are not distinctly separable, and microerystalline in which each granule can be clearly distinguished. Here and there occur a few larger grains of quartz and felspar, but not sufficiently separated from the ground-mass to constitute a true porphyritic structure. 7. (I. 169.)—Boulder on coast, near Annstown, Co. Waterford. Sheet 178. Compact dark grey felsite, well banded (fluidal structure). Under the microscope: Felsitic ground-mass with confused and patchy devitrifi- cation. Hmbedded in the ground-mass are large porphyritic crystals of quartz and felspar, the former corroded, the latter presenting both single and double twin- striation. 8. (I. 109.)—One mile south-east of Ballynacor Cross-roads, Co. Wicklow. Sheet 130. Compact back felsite ; fracture irregular. Under the microscope: Confused felsitic ground-mass, depolarizing in patches, with isolated porphyritic crystals of striated felspar. Grove III.—9. (I. 83.)—Quarter-of-a-mile east of Coatsbridge, on the road from Woodenbridge to Aughrim, Co. Wicklow. Sheet 139. A grey almost phanerocrystalline felsite, with slight parallel structure (probably secondary and due to the earth-movements that have affected this region). Viewed between crossed Nicols the ground-mass has an intricate mosaic-like 548 Dr. F. H. Hatch—L. Silurian Felsites of S.E. Ireland. appearance produced by the uniform distribution of minute prisms of felspar among the rounder granules of quartz. ‘The porphyritic felspar, which is not abundant, occurs in broad rather irregular grains, presenting sporadic twin-striation. Scales, shreds and streaks of both muscovite and chlorite are rather abundant. 10. (I. 80.)—Half-mile north-west of Woodenbridge, on the road from Wooden- bridge to Aughrim, Co. Wicklow. Sheet 139. A grey almost phanerocrystalline felsite, like No. 9. Under the microscope: Microcrystalline ground-mass, with porphyritic grains of quartz and felspar, the former much corroded and rounded, the latter showing occasional twin-striation. 11. (I. 114.)—Ridge, immediately south-east of cairn on Castletimon Hill, Co. Wicklow. Sheet 130. Compact felsite, of light-grey colour, but with dark mottlings. The micro-structure of this rock is extremely varied: at one place cryptocrystal- line, presenting the characteristic dappled ‘‘felsitic’’ appearance between crossed Nicols; at another, almost coarsely microcrystalline, the grains of felspar and quartz being clearly distinguishable. The structure is, however, nowhere truly porphyritic. 12. (I. 96 )—Old Quarry, Little Rock, Arklow, Co. Wicklow. Sheet 139. Light-coloured felsite, spotted white with porphyritic crystals of felspar. Under the mieroscope this rock is seen to consist of fairly large porphyritic crystals of quartz and felspar embedded in a microcrystalline ground-mass. The latter is made up of a uniform minutely granular aggregate of quartz and felspar, together with minute flakes and scales of muscovite and chlorite. The quartz occurs in round and corroded grains, of which two or three are often closely aggregated. The felspar is present in broad rectangular crystals, presenting good crystallographic contours. The crystals occasionally show dual twinning ; more frequently, however, the twinning is polysynthetic, the crystals being striated either in one direction alone (albite type) or in two directions at right angles to one another (albite and perieline types). A slight development of zonal structure is here and there to be observed. In no case was the extinction-angle found to exceed 20°. Group I. comprises felsites containing few or no porphyritic crystals; they are composed mainly of a truly eryptocrystalline or felsitic aggregate. The few porphyritic crystals are not striated, and consist doubtless of orthoclase. Groups II. and III. embrace felsites in which a striated porphyritic constituent is more or less abundant. On the other hand, the felspar of the ground-mass can be safely referred to orthoclase, as in Group I. And it seems likely that the fluctuation in the percentage of potash and soda in these rocks may be due to a variation in the relative proportion between a porphyritic albite-felspar and the orthoclase- felspar of the ground-mass. It is not impossible, however, that the porphyritic felspars may belong to a triclinic potash-soda series (the anorthoclase series of Rosenbusch'), analogous to the soda- orthoclase or soda-microcline described by Forstner ? in the liparites of Pantellaria, by Brogger® in the augite-syenite of Southern Norway, and by Miers and Fletcher* from Kilimanjaro. In all these cases, however, the analyses show the presence of 2 or 3 per cent. of lime, which, with the notable exception of the Little Arklow Rock (No. 12), is almost entirely absent from the Irish soda-felsites. Unfortunately the felspar-grains in the latter are too small for 1 Mikros. Physiog. vol. i. (1885), p. 550. ® Zeitsch. f. Kryst. vol. viii. (1884), p. 125. 8 Die Silurischen Etagen 2 and 3, 1882, p. 261. 4 Min. Mag. vol. vii. (1887), p. 181. T. Mellard Reade—On the Lower Trias. 549 mechanical separation with a view to chemical analysis. Isolation with the Borotungstate solution was indeed tried by Mr. Player, but. without success. Lossen! states that the porphyritic crystals, in the keratophyres described by him, are, in great part, mechanical admixtures of orthoclase and albite, similar to microperthite; but in the rocks under consideration I have been able only in quite isolated instances to record the presence of micro-perthite structure. The rocks embraced in Group III. are slightly more crystalline than the others, the ground-mass being in general microcrystalline instead of cryptocrystalline. No. 12 (Little Arklow Rock) indeed has been placed by Haughton? among his soda-granites; but the structure of this rock can scarcely be termed granitic; at most it could only be called microgranitic (in Rosenbusch’s sense of the term), since it consists of porphyritic crystals imbedded in a micro- crystalline ground-mass. It only remains to point out that the modern equivalents of these ancient felsitic lavas are the rhyolites or liparites and pantellerites, which have been subdivided by Rosenbusch ’ into potash-liparites, soda-liparites and pantellerites, sanidine being the porphyritic con- stituent characteristic for the first, albite for the second, and anortho- clase for the pantellerites. The main difference between the liparites and the felsites lies in the character of the ground-mass, the glassy base of the former being replaced in the latter by the cryptocrystal- line aggregate known as felsitic matter.* Some of the rocks, especially those of Group I., show indications of having consolidated as true glasses (pitchstone or obsidian), as has been proved to be the case in several instances among the felsites of Shropshire and Wales by the valuable researches of S. Allport® and F. Rutley,® who have succeeded in detecting distinct traces of perlitic and spherulitic structure in these rocks. The Welsh felsites are of the same age (Bala) as the Irish rocks, and probably belong to the same series of volcanic outbursts. TV.—PuystocRaPpHy oF THE Lower Trias.’ By T. Meuiarp Reavpsz, C.E., F.C.S., F.R.E.B.A. Introduction. HE origin of the Triassic rocks of Britain is a question that has excited from time to time much interest and varied speculation. The entire absence of fossils in the Lower Trias or Bunter Sand- stone has led the majority of geological reasoners to look to causes 1 Jahrbuch d. k. Preus. Geol. Landesanst. fiir das Jahr 1884 (1885), p. xxxil. 2 Trans. Roy. Irish Acad. vol. xxi. pt. ii. (1859), p. 609. 3 Mikros. Phys. vol. 1. 1887, p. 528. 4 Nothing of the nature of microfelsite (in Rosenbusch’s sense) has been observed by me during the examination of these rocks. 5 On the Pitchstones and Perlites of the Lower Silurian District of Shropshire, Q.J.G.S, vol. xxxiii. (1877), p. 449. § On Perlitic and Spherulitic Structures in the Lavas of the Glyder Fawr, N. Wales, Q.J.G.S. 1879, p. 508 ; and in Memoir of Geol. Survey on the Felsitic Lavas of England and Wales. 7 Read at the Brit. Assoc., Newcastle-on-Tyne, in Section C. (Geology), Sept. 1889. 550 T. Mellard Reade—On the Lower Trias. other than marine action for an explanation of its characteristic features. The late Mr. Godwin-Austen was of opinion that the whole of the Triassic rocks were laid down in freshwater lakes which, passing through the brackish stage, become finally saturated with saline matter through evaporation exceeding the inflow of fresh water. It has been felt, however, by other geologists, that this theory, while accounting fairly well for the upper deposits of the Triassic age, does not fit in with the phenomena of current bedding, the presence and distribution of the numerous quartzite and other well-rounded pebbles, and the comparative absence of marl-beds, which distinguish the Lower Trias or Bunter Sandstones. Hence some well-qualified observers, following Professor Bonney,' prefer to consider that the mass of the sandstones have been laid down by rivers and point to Central Asia, as a region where the same accumulations are now taking place. The late Mr. John Arthur Phillips suggested that much of the sandstone displaying the well-rounded or “ millet-seed”’ grain, supposed to be the distinguish- ing characteristic of the upper and lower beds or divisions of the Bunter Sandstone, was accumulated by wind action, it being main- tained that the individual grains could not have been worn to so spherical a form by any other agent.? A combination of these two views seems to constitute the prevailing if not the finally accepted theory of the origin of a large proportion of the dpiasste Sandstones of Britain. My attention, which has for a long time been Bet by these interesting speculations, was some time since more specifically directed to the subject. Having for engineering and other purposes to examine considerable areas of the Triassic deposits of the North- west of England, the opportunity of further prosecuting the inquiry was eagerly seized. The Triassic and immediately overlying and underlying rocks of the North-west of England and the Midland Counties * were for the purposes of the Geological Survey classified by Professor Hull as follows: Al. Rheetic or Penarth beds occurring at Copt Heath and the South-west of England. A2, New Red Marl. Red and Grey shales, and marls sometimes micaceous, with beds of rock salt and gypsum containing Estheria and Foraminifera (Chellaston), A3. Lower Keuper Sandstone. Thinly laminated micaceous sandstones and marls (waterstones) ; passing downwards into white, brown or reddish sandstone, with a base of calcareous conglomerate or breccia. Cl. Upper Mottled Sandstone. Soft bright-red and variegated sandstone (without pebbles). C2. Pebble Beds. Harder reddish-brown sandstone with quartzose pebbles, passing into conglomerate with a base of calcareous breccia. C3, Lower Mottled Sandstone. Soft bright-red and variegated sandstone (without pebbles). Triassic SERIES. 1 Presidential Address, Geological Section of British Association, 1886. 2 On the Constitution and History of Grits and Sandstones, Q.J.G.S. 1881, p. 27. 3 Triassic and Permian Rocks of the Midland Counties of England, Memoirs of the Geol. Survey, 1869, p. 10. T. Mellard Reade—On the Lower Trias. 551 1. Upper Permian. Red marls with thin-bedded fossiliferous limestones ae (Manchester). a 8 . & ( Red and variegated sandstone (Collyhurst, Manchester). Ba 9. == ) Reddish-brown and purple sandstones and marls with calcareous Ay 33 conglomerates and trappoid breccia (Central Counties). Previous to Prof. Hull’s investigations no subdivisions had been recognized in the Lower Trias or Bunter Sandstone, but that geologist, as the result of an extensive survey, considered that there were well-marked lithological differences in the beds which justified a classification into three horizons, namely,—1 Lower Mottled Sandstone; 2 Pebble Beds; 3 Upper Mottled Sandstone. It is upon this scheme that the Geological Survey maps were and have since been constructed. Considering the difficulties of the survey, much of the country being deeply drift-covered, the maps have fairly represented the geology of the areas surveyed, especially in those localities where the outcrop could be studied. It is in those places where the nature of the rocks could only be ascertained by boring that the weak points of a classification founded on lithological differences has naturally developed itself. In view of the numerous borings for water supply and for other purposes since made in Lancashire and Cheshire, certain modifica- tions have had to be made in the colouring of the maps showing the distribution of the subdivisions of the Bunter, and in some cases it is impossible to make the maps conform to nature and be logically consistent with the classification. Far be it from me to in any way seem to detract from the merits of the early attempts to conquer difficulties, especially where any classification is surrounded with pitfalls as it is in this case. It is a trying time for the geological surveyor when he is asked to predict the strata likely to be met with in a given bore-hole, yet this is what is demanded from a geological map; and if it occasionally errs, can we wonder ? Characteristics of the Triassic Sandstones. For the purposes of this paper it will not, however, be necessary to discuss these refinements of subdivision. I propose to treat principally of the Bunter Sandstone and its mode of origin, and with this object in view it will be sufficient to look upon it as a massive agglomeration of siliceous sandstones of varying fineness or coarseness of grain,.sometimes rounded, sometimes angular, more or less coloured by peroxide of iron, and often cemented together by secondary silica, or having crystalline growths thereon in optical continuity with the original quartz of the grain, even though the grain may have been previous to deposition well rounded by attrition of the surface. Within the interstices of the stone, and probably combined with the colouring matter, is a deposit of calcareous matter consisting of carbonate or sulphate of lime, sufficient, after continual circulation of water in the rock when brought about by artificial means, such as pumping, to impart a considerable amount of tem- porary and permanent hardness to the water. 552 T. Mellard Reade—On the Lower Trias. If we add to these characteristics the occurrence of well-rounded pebbles of liver-coloured and of clear translucent quartzite, white vein quartz, and other hard rocks, from the size of walnuts to an occasional specimen having a longer diameter of four or five inches, we shall have exhausted our lithological description. It is, however, to be specially noted that these pebbles occur often sparsely distributed through the rock, sometimes in nests, and in other cases in such numbers as to deserve the name of “conglomerate beds” given to them by Professor Hull. So far as my experience goes, the liver-coloured quartzite pebbles are confined to the Bunter Sandstones; but I have not been able to satisfy myself so far that these pebbles occur at a definite horizon in the Bunter, except locally speaking. Indeed, I am much inclined to believe that in some cases the theory of the pebbles being confined to a central subdivision has led to a misinterpretation of these rocks. Speaking broadly, there is a distinct lithological difference be- tween the Keuper and the Bunter; for although in most cases it would not be possible to distinguish the rocks in local specimens, we cannot point to any rocks in the Bunter which would be mistaken by a practical man for Storeton or Grinshill building-stone. The transition from the Bunter to the Keuper is also more marked than between beds of the Bunter, nor is there in the Bunter any equiva- lent of the Waterstones of the New Red Marl. The Bunter is evidently a sandstone deposit, while the Keuper, often beginning with a conglomerate bed, shades off into a lithologically distinct stone succeeded by thin-bedded sandstones, and finally by the great deposit of saliferous marls. These physical peculiarities are well known to geologists who have worked these rocks; but it is necessary for my argument to restate them in this connected form. Theory of the Origin of the Triassic Rocks. Hitherto I have said nothing of the topographical relations of the Triassic rocks ; but as the distribution of the sandstones specially bears upon their origin, this cannot be neglected. Unfortunately of the arid sandy region of Central Asia, which it is suggested best explains the mode in which these Triassic Sandstones have accumu- lated, not much is known.! If, however, the Bunter Sandstone is a riverine deposit, we would expect it to follow well-marked topographical features. Although there have been great orographic changes, some folding, and much faulting since the Triassic age, certain great features, such as the Pennine Chain, still remain in a modified form. If we try in imagination to reconstruct a river, valley or valleys, or even a sandy plain, representing the deposits as they are conceived 1 The following papers bearing upon the subject are well worthy of study: “ On the Nature and Probable Origin of the Superficial Deposits in the Valleys and Deserts of Central Persia,” W.T. Blanford, Q.J.G.S. 1873, pp. 493-502. “ Alluvial and Lacustrine Deposits and Glacial Records of the Upper Indus Basin,” F. Drew, Ibid, pp. 441-71.—‘‘ Journal Across Central Asia,’? by Lieut. Younghusband, describing Gravels from the Altai Mountains and Sandhills, 900 feet high, “‘Nature,” 1888, May 17, pp. 65-6. T. Mellard Reade—On the Lower Trias. 593 to have been laid down on the riverine hypothesis, we are met with numerous difficulties, which I for one find it impossible to solve. The Triassic Sandstones are found on both sides of the Pennine Chain ; they occupy valleys in older formations such as the Vale of Clwyd, where they are flanked by Silurian hills, and in the Vale of Eden by the Carboniferous: and everywhere they appear to follow what seem to be the remains of the orographic contours of the ancient land. So far as my experience goes, there is a general tendency for the sandstones to thin off against these boundaries of more ancient rocks, even where these boundaries are represented by faults. No doubt the Triassic deposits formerly overlapped their present boundaries to a considerable extent; but there is a limit to this where they abut against high ground, for there is every reason to believe that the pre-Triassic rocks preserve in many respects their pre-Triassic orography. My study of the origin of mountain-ranges has convinced me of the permanence of the more pronounced orographic features of a country, or what may be called lateral-pressure upheavals, which, while modified by faulting and denudation, can only after a lengthened period be finally destroyed by these combined agencies. From these considerations it is highly probable that the Triassic rocks which remain represent the deeper part of the basins in which they were laid down, and that they never encroached extensively on the Pennine Chain or the high land of North or South Wales. In the case of more extensive and widespread deposits it is the thickest parts that, being upheaved into mountain ranges, have been most quickly destroyed by denudation. The Triassic rocks have not been affected in this manner, and therefore retain in a certain degree the basin-like form in which they were deposited. One of the most remarkable features of the Triassic Sandstones is, speaking broadly, the persistency with which their lithological characters hold out over extensive areas, and their apparent independ- ence of the bed-rock on which they lie, or that of the hills bounding the valleys containing them. Very few pebbles of the surrounding rocks are found in the Pebble-beds of the North-west of England, and it is mostly in the Midland Counties where any considerable pro- portion of local rocks occur in the conglomerate beds. On the other hand, the Permian beds underlying them are often largely made up of local rocks; instance the limestone breccia of Alberbury, composed almost wholly of fragments of Carboniferous Limestone, or the somewhat similar “ Brockram ” of the Vale of Eden. Could we with any certainty localize the origin of the materials of the sandstones, a considerable. step would be made towards unravelling this knotty problem; but even as regards the contained quartzite pebbles, one set of observers contend that they came from the north, another from the south, while a third considers that they have been derived from the destruction of rocks in Mid England." It would certainly seem, whatever be the direction from which 1 See Bonney, Address to the Geological Section of British Association, 1886, and Grou. Mag. 1883, p. 199; 1888, p. 55.—Harrison, Proc. Birmingham Phil. Soc. 1882, vol. ii. p. 157.—Hull, Grou. Maa. 1883, p. 285. 554. T. Mellard Reade—On the Lower Trias. the pebbles have travelled, that they are the product of other areas, and this will hold good, whether they resulted from the direct destruction of quartzite rock, or are of secondary derivation from a pre-existing conglomerate. In framing a theory of the origin of the Bunter Sandstone, it appears to me that we cannot altogether detach it from a considera- tion of the underlying Permian. Before these Permian deposits were laid down, and during the time of accumulation, extreme denudation of the Carboniferous rocks took place, and much of the material was derived from them ; but on the incoming of the Trias, the materials became of a more uniform character, and were to a large extent of distant origin. It is not, however, improbable—nay, it is extremely likely—that the drainage or leaching of the Carboniferous rocks may have supplied the per- oxide of iron with which the grains are coated, and which gives the sandstones their distinctive colour. We know also, for the records are unmistakable, that an enormous mass of Carboniferous sand- stones and grits have been stripped from the Pennine Chain by denudation, and it is not unreasonable to ask what became of the resultant sand during Triassic times. The same may be said of the Old Red Sandstones of Herefordshire and the Quantocks. It would indeed seem incredible if these important formations did not yield their quota of sand to the Trias, though the absence of Carboniferous sandstone boulders in the Trias is remarkable. May - they not have been ground to sand by currents which we know were capable of rounding the hard quartzite pebbles? It appears to me that neither the distribution, the uniform character, nor the great thickness of the Bunter Sandstone, accords with the subaerial river-delta theory. No instance that I am aware of has been recorded of the finding in Triassic Sandstones of anything like a river-channel. It is difficult to conceive of a river unless fed from some very peculiarly constructed rocky area bringing down nothing but sand. The Nile does not do it; on the contrary, it covers the desert sands with fine mud. On the other hand, the subaerial building up of sandstones, proved by the boring at Bootle to be over 1200 feet thick, does not seem to be, considering what has been preserved of the orographic features of the time, a very plausible supposition. While considering with many other geologists that the lacustrine theory of the origin of the Bunter Sandstones may be dismissed as altogether inadequate to account for the great prevalence of current bedding, the presence of well-rounded quartzite and other pebbles, and the absence of marl except in occasional thin beds, the substituted riverine theory seems to me to fail for the reasons already given. So far I have indulged principally in destructive criticism, pro- verbially the easiest sort of work, but not on that account less necessary in an attempt to arrive at truth. J have, however, else- where already indicated an alternative theory,’ which I submit in more detail for the consideration of my brother geologists. 1 Physiography of the Triassic Period, ‘‘ Naturalist,’ pp. 108-111, April, 1889. | T. Mellard Reade—On the Lower Trias. 555 If, as I have reason to believe, the Triassic deposits of the North- west of [ngland as they now exist fill up the sites of pre-Triassic basins and valleys, the absence of underlying Permian rocks over a large area surrounding Liverpool is a remarkable fact. The Bunter Sandstone was proved to be at least 1200 feet thick in the Bootle boring, and the additional 200 feet of sandstones and marls below that depth did not present any decided Permian characteristics. They became gradually more calcareous and of a deeper purple colour. It is on the margin of the Triassic deposits that the undoubted Permians occur, and these facts would seem to point towards an unconformity between the Trias and the Permian. If this be a legitimate deduction, the Permian rocks must have been largely removed by denudation from these valleys before the Trias was _ laid down. Whence then came the physical change which turned the valleys into areas of deposit? If they were filled up in the way the sub- aerial delta theory requires, we shall have to postulate the existence of very high land, probably of a granitic nature, for a river could not pile up a homogeneous delta of sand and pebbles from 1200 to 2000 feet thick without having a considerable gradient. If then such a plateau or Alpine range then existed, what has become of it? Why should it have been destroyed, when a lesser orographic feature like the Pennine Chain remains ? If, however, we look upon the areas in Lancashire and Cheshire occupied by the Triassic rocks as subsided valleys forming arms of the sea in Triassic times, and we can show with a reasonable degree of probability that sandstones having the characteristics of the Bunter could be laid down under such conditions, we shall have advanced a considerable step towards a solution of the problem. I have shown that tidal action affects the bottom of the sea to the profoundest depths,’ and is especially effective in embayments and straits. The Trias of Cheshire and partly that of Lancashire lies in an embayment between the Carboniferous mountains of Wales and the Carboniferous hills of Lancashire and Cheshire, and this is connected with the Birmingham Triassic Basin and the strait-like neck of Trias at Bridgenorth. Indeed, if a subsidence of England and Wales were to take place now to the extent of 400 feet, most of the Triassic deposits would be submerged, and the embayment, though more extensive, would ap- parently follow or be concentric with the Triassic boundaries. This has long appeared to me a remarkable fact, and a strong testimony of the permanence of certain orographic features of the earth’s sur- face. In this connection we must not lose sight of the possibility of a great extension of the Triassic Sandstones existing under the bed of the Irish Sea. Of this there is the strongest probability from the known existence of bordering deposits of Trias on the coasts of England, Scotland, and Ireland, sending offshoots up the valleys in the way already described. 1 Tidal Action as a Geological Cause, Proceed. of L’pool. Geol. Soc. 1873-4 ; Tidal Action as an Agent of Geological Change, Phil. Mag. May, 1888. 556 T. Mellard Reade—On the Lower Trias. But where have the bulk of the materials travelled from? If we look to the geological structure of the lands to the north, there do not appear to exist rocks in sufficient quantity of a nature to supply the great mass of quartzose sand constituting so large a bulk of the Trias. The English Channel, judging from the islands dotted about it and the peninsula of Cornwall, appears to be a granitic and gneissic area, and it is possible that much of the Triassic Sands may have travelled from this locality. To bring this material through subaerial denudation within the distributing grasp of the tides a regional elevation of a thousand feet would be largely effective. It would become a land area supplying quartz-grains to build up the sandstones and decomposed felspar as a contribution to the marls. From the indestructibility of the quartz-grains they would last longer and travel farther than the other mineral constituents of the rock. Concurrently with this elevation the land occupied now by the Triassic deposits must have been relatively depressed, giving entrance to the sea in the way already sketched out. It may possibly be urged in objection to this view that there is no connection between the Lower Trias of the South-west of England and that of the Midlands. We know, however, that there is as regards the Upper Trias along the Severn Valley, and it is quite likely that to the east of this line the Lower Trias may underlie the Lias' and Oolites. The lie or disposition of the overlying formations favours this idea, and there are no borings to disprove it. Any one who has practically attempted to prove continuity by borings over even a limited area knows how uncertain the method is. It is also not impossible that the anticlinal ridge—not necessarily an impassable barrier of Paleeozoic rocks—eonnecting the Mendips in Somersetshire with the Belgian Coal-fields, so sagaciously pointed out by the late Mr. Godwin-Austen, may have yielded contributions to the Trias, for the existence of Old Red Sandstone in this ridge under London has been proved. May not some of the quartzite pebbles have had their origin here also ? for, as already stated, they diminish in size and number as we go northwards. Even at Market Drayton in Shropshire the pebbles in the conglomerate are more numerous and larger than in Cheshire or Lancashire. Pebbles of quartzite containing fossils similar to those of Budleigh Salterton are reported by Mr. Jerome Harrison and others as occurring in the Trias of the Midlands and in the drift derived therefrom. The boulders and pebbles of Budleigh Salterton also appear to be larger on the average than those of the Midlands, which facts seem to point to a common derivation and a longer travel of those of the Midlands.’ 1 See records of some remarkable borings in Woodward’s “ Geology of England and Wales,’’ second edition, facing p. 612, ‘also the accompanying Geological Map of England and Wales. * See Quartzite Pebbles of the Drift and Triassic Strata of England, Proc. of Birmingham Phil. Society, vol. iii. p. 157 (1882); On the Triassic Rocks of Somerset and Devon, W. A. E. Ussher, Q.J.G.S. vol. xxxii. p. 567 (1876) ; Notes on the Classification of the Triassic Beds of the South-West of England, H. B. Woodward Geol. Survey Memoir on E. Somerset and Bristol Coalfields ; : Red Rock Series of the Devon Coast, Rey. A. Irving, Q.J.G.S. 1888, p. 149. T. Mellard Reade—On the Lower Trias. 557 Then again, as before stated, although Carboniferous Sandstone boulders are scarce in the Trias of the North-west of England, we cannot reasonably ignore the fact that massive sandstones and grits exist in the Pennine Chain, which have been subjected to vast denu- _ dation. Considering that the strong current bedding indicative of turbulent water action is one of the characteristics of the Triassic Sandstones, and one of its difficulties, may we not reasonably assume that Sandstone boulders would soon get ground to sand? ‘There is very little of the marginal boundary of the Trias left in the North- west of England, and it is in this fringe that Sandstone boulders would most likely occur. Marginal deposits of local rocks seem to have been preserved in Somerset and Devon." Given these materials, tidal action, as I have proved in the papers referred to, is quite capable of selecting, distributing, and accumu- lating them in the form in which they appear in the Triassic deposits. On this theory we are not limited to depth, as the tidal wave produces currents acting through the full depth of the water from the surface to the bottom, and current-bedded sandstone might be laid down by this agent at a depth of many hundred feet and over very extensive areas. These ideas relating to the physiography of the Triassic period have been placed before the Geological Section of the British Asso- ciation simply as suggestions for their consideration. The subject is beset with difficulties, but in solving such a problem all possible agencies must be tried and discussed. A new hypothesis also has this merit, that it guides men’s thoughts into fresh channels, and it is only by observations renewed again and again on various theoretical lines that the truth can be at last reached. There is, doubtless, one objection that will be urged against the theory here set forth, namely, that it does not account for the entire absence of fossils in the Bunter Sandstone, while the subaerial river-delta theory does. This, doubtless, is one of the many difficulties of the question ; but on the other hand if marine fossils had been found, the difficulty of interpretation would not have existed, nor would it had the sandstone contained fresh-water remains. This argument, although possessing considerable force, is only one of negative evidence -pro- verbially unsafe. Also, if we admit marine action, it does not exclude that of the winds. Molian deposits would be certain to be extensively developed on the margin of such sand-laden waters, and thus sandstones, which do not contain pebbles, have much rounded grains and are irregularly current-bedded may be due to wind-action. As regards the Keuper Marls, the dessicated lake theory fits in well with their characteristics, and it may be that the Keuper Sand- stones show the gradual passage from marine to fresh-water con- ditions. The upper beds of the Keuper Sandstones show well- developed ripple-marks which are not common, but are not abso- lutely absent in the Bunter. The replacement of massive by thin sandstone beds, and the intercalation of shales, together with the 1 See papers already quoted. 508 | Notices of Memoirs—W. H. Hudleston— presence of pseudomorphs of chloride of sodium, show that a new condition of things set in with the Keuper. In conclusion, I may point out while on negative evidence that the absence of saline deposits in the Bunter is on the other hand against the subaerial river-delta hypothesis, as the sandy deposits to which they are com- pared often eventually absorb the rivers which create them ; and this applies to the North of Africa as well as to the Asiatic example. INKS Zens (Oeey AM rasan Oatisysie Tue Grotocy or Devon, Facts anD INFERENCES, FROM THE PRESIDENTIAL ADDRESS TO THE DervonsHirnE AssocratTion. By W. H. Hupuzsron, Esq., F.R.S., Sec.G.8., ete. August, 1889. Part II. (Concluded from November Number, p. 514.) Tavistock CounTRY. \HE geological phenomena in the neighbourhood of Tavistock are of such interest that I cannot do better than close this address with a brief allusion to some of the features of the west side of Dartmoor, and the adjacent country. It is a region which has always presented peculiar difficulties, but - the new line of railway in course of construction may help to clear matters up. The subject can be grouped under four headings: {1) The structure of the country; (2) the nature of the basic igneous rocks, or ‘‘greenstones”; (3) Dartmoor; (4) the metal- liferous deposits. (1) The structure of the country on the west side of Dartmoor differs considerably from that on the east side, more especially in the fact that the Devonian beds are represented as dipping towards the sea instead of away from it; at least this is the case for several miles immediately north of Plymouth. Further towards the north, in the direction of Tavistock and beyond, there would seem to be a complexity of structure unusual even for Devonshire. Con- sequently the boundary between the Devonian and Carboniferous, as laid down in the Survey Map, may be subject to considerable revision. Mr. Worth astonished us lately at the Geological Society by the statement that the town of Tavistock is actually on the Carboniferous, and yet that, owing to a complex series of foldings, the Devonian rocks are brought up on both sides.. I know of no spot in the United Kingdom where the geological boundary-lines seem to be so much under discussion at the present moment. Although Mr. H. B. Woodward, in the map attached to the “Geology of England and Wales,” follows De la Beche in assigning the Brent Tor district to the Carboniferous, it has long been claimed as Devonian by some geologists. These views are perhaps the result of Mr. Rutley’s interesting work on the schistose volcanic rocks west of Dartmoor, described as consisting of alternations of lava- flows, tufis, and tufaceous sediments. That this class of rock, locally Presidential Address—The Geology of Devon. 009 known in its vesicular form as “honeycomb dunstone,” was of a volcanic nature, had long ago been recognized by De la Beche; but it was the late Mr. John Arthur Phillips who first clearly demon- strated, in his classical papers on the Cornish “ greenstones,” that many of these beds were actually lava-flows. Mr. Rutley went a step further, and considered that he had found in Brent Tor a frag- ment of one of the old volcanic necks. His famous diagram, with its column of ashes flattened by the wind, described by himself as as “a chimera which may embody a certain amount of truth,” is familiar to all geologists. Nay so graphic was the picture, and so convincing the arguments, that a certain Mr. Thorpe fancied that he had corroborative evidence of the prevalence of the south-west wind in Devonian times, because, forsooth, he had found lapilli from Brent Tor in the joints of a limestone at Newton Abbot. Let us express a hope that before the Association next meets at Tavistock the boundaries between the Devonian and Carboniferous may have been made as clear as noonday, and accurately laid down on a six-inch map, which shall itself be a model of chartography. (2) We must now take into consideration the nature of the basic igneous rocks, commencing’ with those which are interbedded, most of which are now said to be of Devonian age. Before doing so it will be necessary to say a few words about the “killas,” a very loose term better understood by miners than geologists. Judging from Mr. Worth’s remarks on the stratigraphical relations of the Devonian rocks of South Devon, most of the “killas” of this district belongs to the grey and drab slates intersected by lodes and elvans, which was described by Conybeare as the metalliferous series : above this comes a group more variable in its nature, which is especially characterized by interbedded volcanic rocks, and Mr. Worth suggests that the Brent Tor series may belong to this group : ahove these again are the purple and green slates immediately under- lying the Plymouth limestone. The main point to notice is, that the whole of this slaty series is regarded as below the Plymouth limestone. Consequently it must belong to the lower part of the Middle Devonian, and possibly to even lower beds. Mr. Rutley, if I recollect rightly, regarded the Brent Tor series as possibly in the Upper Devonian. The interbedded basic igneous rocks, then, are placed by Mr. Worth a long way below the Plymouth limestone ; whereas the late Mr. Champernowne, in an interesting posthumous communication to the Geological Society, was disposed to regard his Ashprington voleanic series as above the main limestone of that district. In reference to this difference of opinion two points seem to present themselves for consideration. Firstly, that the schalsteins need not be confined to any particular horizon in so thick a series as the Middle Devonian ; secondly, that the phenomena of extravasation, whether interbedded or transgressive, is limited, with very un- important exceptions, to the southern portion of the county, from whence the line of igneous products may be traced into Cornwall. Hence the area of erupted rock is local, and to a certain extent 560 Notices of Memoirs—W. H. Hudleston— linear, and is probably not absolutely confined to any particular geological horizon. The interbedded basic igneous rocks have been described by numerous authors, and their general petrographic features are fairly well known. In Northern Cornwall, according to Mr. J. A. Phillips, these ancient lavas are called ‘“dunstones.” Specimens analyzed by him were found to contain 42 per cent. of silica, over 20 per cent. of alumina, and the alkali is almost entirely soda: the amount of lime is nearly twice that of magnesia, and there is over 12 per cent. of protoxide of iron. From a chemical point of view these rocks, then, are allied to the basalts. The intrusive ‘“ greenstones” are classed by Mr. Worth under three heads. They are sporadically developed, but seem to be most numerous and of the largest size in the vicinity of Dartmoor: they are believed to be older than the Dartmoor granite, which is said to alter them. If the Survey mapping is correct, the so-called gabbros between Marytavy and Wapsworthy occur in Carboniferous rocks, and must of course be younger than the beds into which they are intruded. ‘These gabbros, Mr. Worth considers, are the vestiges of a widespread pre-Dartmoor igneous activity, producing basic rocks. He points out that their relations to the granite, both here and in Cornwall, are too persistent to be accidental, and he suggests that they may represent the basic forerunners of the more acidic granites. The age of the rocks into which the Marytavy “gabbros” have been injected still remains to be settled, but the notion that either they or the granites have brought up the lowest stratified rocks is not borne out by experience in other parts of the area round Dartmoor. (3) Having now cleared the way a little by a brief glance at the containing rocks, we are in a position to attempt the study of Dart- moor itself, that supreme monument of the old eruptive forces. Dartmoor, as every one knows, is contained partly in Devonian and partly in Carboniferous rocks, and from the position of the Posido- nomya-beds it is probable that the lower part of the Carboniferous adjoins the granite. Mr. Ussher, speaking of the beds on the northern and eastern flanks of Dartmoor, observes that the Culm- rocks dip off the granite above Belstone in a marked manner. He also says that the Culm-rocks on the north are roughly parallel in their strike to the margin of the granite, whilst on the east and west their strike is cut off, so to speak, by the granite or else deflected. These considerations are of importance as showing how the granite lies in its case. From what has already been said, it is perfectly clear that this granite is in nowise connected with anything of the nature of an anticlinal axis bringing up older rocks. In fact on the east side, where it abruptly terminates, its relations to the adjacent country are almost those of a synclinal. On the Tavistock side its relations with the adjacent country are more obscure, owing to the stratigraphy of the district being as yet undetermined. Moreover, there is pro- bably underground connection on this side, through Hingston Down, with the granite boss of Brown Willy. Presidential Addvess—The Geology of Devon. 561 The above considerations tend to show that the relations of the granite to the surrounding rocks are somewhat peculiar, and that it is not exactly easy to frame a theory to satisfy all the conditions. The composition, which is that of a normal potash granite, and the contact phenomena, are clearly against the notion of any large absorption of the containing rocks, such as are now accessible to observation. ‘There has been much nonsense talked about granites being the result of the extreme metamorphism of the beds in which they occur. Mr. J. A. Phillips in his paper “On the Rocks of Cornwall in relation to Metalliferous Deposits”’ showed very clearly that, although the different kind of killas vary materially in composition, under no circumstances could the mere re-arrangement of the constituents result in the production of granite. _ He gives a table with the chemical compositions of ten varieties of Cornish killas, showing a range in silica from 38 to 68 per cent. and of alumina from 10 to 24 per cent. The alkali is mainly soda, and of this there is a considerable amount in some specimens, pointing to the conclusion that killas has been largely derived from the dis- semination of very fine volcanic matter of a basic composition. This coincides with the prevalence of contemporaneous volcanic phenomena. It is worth noting that the roofing-slate of Delabole affords an exception to this rule, in containing more potash than soda. As there is no reason to suppose that the early chemical history of the Dartmoor granite differs materially from that of the Cornish granites, their sources must have been deep-seated, and they must have originated under the ordinary conditions which produce the granitic magma, whatever those may be. The main questions re- maining to be considered are the period and circumstances under which the Dartmoor granite assumed its present position. There is no evidence at present, as far as I know, which would enable us to fix the period any nearer than the somewhat vague date “the close of the Carboniferous.” Dr. Barrois says that many of the Brittany granites are of Carboniferous age. But in the case of Dartmoor it is probable that the great foldings of the Hercynian mountain-system had been mainly effected, and the synclinal of Devonshire formed, before the granite was insinuated. In position the mass of Dartmoor is outside the axis of the Cornish granite ; if their alignment was followed the centre of Dartmoor would be about Hatherleigh. Hence the stratigraphical position differs some- what from that of the Cornish granites, although possibly their age may be quite the same. It is enough to know that an immense physical revolution was effected all over the British Isles between the close of the Carboniferous and the beginning of the Permian, and the intrusion of the Devon-Cornwall granites must have taken place either then or in early “red rock” times. Next, as to the circumstances under which the Dartmoor granite found its way into its present position. Last year Mr. Ussher treated 1 Quart. Journ. Geol. Soc. vol. xxxi. p. 319. DECADE III.—VOL. VI.—NO. XII. 36 562 Notices of Memoirs—W. H. Hudleston— this great question with characteristic ingenuity, and showed pretty conclusively that neither the punching theory nor the absorption theory would meet the facts of the case. De la Beche gave us a valuable hint, as indeed he was in the habit of doing, when he inferred that, owing to the volcanic activities which had prevailed in the area during the deposition of the Paleozoic series, a line of least resistance to a body of granite, impelled upwards, might have been formed. In this way the granite of the great bosses may have been forced through ground already weakened as the site of old volcanic vents—such as Brent Tor, we might add. Of course, it must be remembered that the contacts we now see only represent a certain stage in the relations between the granite and its case. A million years ago, when the country was much higher relatively, the contacts may have presented a somewhat different phase, whilst it is certain that those who are able to inspect the contacts after another million years of atmospheric denudation, will at least get much nearer to the roots of the matter. As far as I am able to judge from Mr. Ussher’s descriptions, there are indications of a considerable lateral thrust on the north and on the south side of the mass, parallel to the mean strike of the enclosing beds. This looks very much as if the main displacements which took place were lateral, the beds yielding to the pressure gradually, and thus helping to intensify the flexing of the district. How far the evidence is in favour of Mr. Ussher’s suggestion that Dartmoor is a laccolite, insinuated at the junction of Devonian and Carboniferous rocks, I am unable to say. This seems a somewhat ignominious termination to a career which patriotic Devonians have regarded as nothing less than the plutonic supply-pipe of a regular ~ volcanic cone, more lofty than that of Etna. Possibly the two theories may be reconciled by regarding the supposed laccolite as a kind of reservoir, or local thickening in the pipe. It was Professor Bonney who first set the Devonshire geologists on the look-out for the vestiges of the great Devonshire volcano. Not a mere Brent Tor this time, erupting its lavas into the Devonian Sea, but one of a line of lofty peaks of far later date. “‘ Among the many excellent geologists and enthusiastic students of the West of England,” said he, “is there no one who will undertake to replace the covering which has been stripped from the granitic bosses ?”’ He also indicated that a thorough study of the “red rocks” of Devonshire would yield important results in this direction. Mr. Worth is amongst those who have responded to this challenge, a circumstance to which allusion has already been made in dealing with the New Red question. It is somewhat singular that if there really was a volcanic cone covering the Dartmoor pipe, the traces of it should have to be sought at the eleventh hour in the “red rock ” breccias. These ought to be full of unmistakeable fragments of old acidic lavas, and of the felsites which are structurally intermediate between such lavas and granite. Possibly the want of adequate petrographic knowledge may have hitherto retarded the discovery, and we naturally await the result of further investigations. Presidential Address—The Geology of Devon. 563 But Mr. Worth himself has supplied evidence which goes far to explain the presence of remnants of felsitic, and even of volcanic rocks, in accumulations more recent than the “red rock” breccias. Such remnants are much more likely to have been derived from the elvans, which form so characteristic a feature in the country between the Dartmoor and Brown Willy granites, and some of which probably reached the surface in a more glassy condition than the portions now accessible to operations. Besides, even the existing dykes are represented in some cases as developing a semi-vitreous ground-mass with porphyritically imbedded crystals. Theoretically it is extremely probable that the granite bosses of Devon and Cornwall may have passed upwards into volcanic rocks, and that consequently they represent a line of eruptive vents which were possibly active in Permian times, or those immediately preceding. But the petrological evidence alone is not conclusive. If we suppose that the “red rock” breecias are of Triassic and not of Permian age, all, or nearly all, traces of the volcanoes might have been removed before the breccias were accumulated. Clearly the granite, with its characteristic crystals of orthoclase, had been laid bare when the beds containing Murchisonite were deposited. As regards the composition of the Dartmoor granite, the accessory minerals such as schorl, and the proneness of portions to kaoliniza- tion, are especially noteworthy. This latter feature has a tendency to produce unequal weathering, and it is not at all improbable that the Tors are in a great measure due to the unequal weathering brought about by this cause. They represent portions which, in the hour of trial, were harder and perhaps chemically more stable, and consequently less liable to disintegration. The forms of the Tors, as was pointed out by Prof. Rupert Jones and more recently by Mr. Ussher, have been largely determined by the arrangement of divisional planes, the mass being intersected by what the latter calls impersistent cracks, running more or less horizontally and crossed vertically or obliquely by joints. Variation in the direction of these joints is accountable for much of the variety in the Tors themselves. (4.) The Metalliferous Deposits—The abundance of schorl, espe- cially on the edges of the granite, and the kaolinization of the felspars, are indirectly connected with the last subject which it is proposed to bring to your notice; viz. the origin of the metalliferous deposits for which this region is so famous. It is, I believe, admitted that the great east-and-west fissures through which the elvanite has been injected were formed after the consolidation of the main mass of the granite, though their chemical composition points to their having been derived from the same magma as the granite. The next step in this curious underground history appears to have been the formation of a series of empty fissures, most of them having a more or less east-and-west orienta- tion. And now commenced a fresh set of phenomena which, in an extremely modified sense, may be said to be still in operation. The fissuring of this region was probably due to reaction after the strain consequent on the system of folding, to which allusion 864 Notices of Memoirs—W. H. Hudleston— has been so often made. When first this fissuring, or gaping of the rocks, occurred, there was a supply of molten silicates from below more than sufficient to fill up the void. But, as often happens in volcanic regions of modern date, the last stage of primary activity is represented by fissuring without injection of molten matter. A number of open cracks are thus formed, which favour the circulation of underground waters, often intensely heated, and not seldom pass- ing off as condensed steam where they happen to reach the surface. In Devonshire and Cornwall, the period when this phase was at. its height occurred most likely in late Permian and early Triassic times.! But, as every one knows, there have been many periods of shifting amongst the rocks; and doubtless the country must have participated in the great Tertiary earth-creep which folded the Downs and the Isle of Wight, about the same time that the Alps were being raised into a mountain-chain. Hach successive move- ment would be apt to produce modifications in the underground circulation, cramping it here and stimulating it there; and doubtless, as the temperature decreased, the solvent powers of the waters would diminish also. ; To such underground circulation in old volcanic districts like this, most of the phenomena in connection with metalliferous veins are due, though it must always be remembered that here we see a plutonic phase of what were volcanic activities at higher levels in earlier times. Fifty years ago De la Beche and the first Surveyors evinced an intense interest in this subject, and in the Memoir already referred to many hypotheses of origin are discussed. Since those days the world has been revolutionized in more ways than one, and in no way more than in the transfer of mining enterprise. But the experiences of the last five-and-twenty years in the Tertiary volcanic districts of North America have not been lost upon the numerous able men who have been employed as engineers or surveyors in those highly metalliferous regions. The late John Arthur Phillips left a record of his great knowledge and experience in his excellent treatise on Ore Deposits. And I have no doubt that many here are more or less acquainted with the important works of the French savant Daubrée, whose “ Etudes synthétiques de Géologie expérimentale,’ and “ Les eaux souterraines aux époques anciennes,” furnish us with an immense amount of information on the origin of metalliferous veins. Briefly, it may be said that the underground circulation theory is the one most generally adopted, the chief difference of opinion being as to the relative importance to be assigned to lateral secretion and to ascension respectively ; or, stated in simpler terms, whether 1 Since the publication of portions of the address in the local papers, Mr. Thomas Collins, of Redruth, has written to say, ‘‘he considers there is evidence in the Tavistock district that the metalliferous deposits containing copper-ores had been formed in the Devonian rocks before the deposition of the main mass of the Carbon- iferous. The large copper-lodes of Mary Tavy, for instance, are in Devonian rocks, and cease altogether on coming into contact with the black schists of the Carbon- iferous.’’ It is suggested that this may be due to faulting at the junction. Presidential Address—The Geology of Devon. 565 the vein-material comes from the sides or from below. It is reason- able to suppose that both sources may have contributed to the supply, though in certain cases a change in the deposits, accompany- ing a change in the country rocks, would seem. rather to favour the notion of lateral secretion. Thus Mr. Phillips remarks, with regard to the Tavistock district, that the copper-ores are often associated with a blue clay-slate. If the slate becomes deeper in colour, iron- pyrites alone occurs; and if the rock becomes quartzose, even the pyrites disappear. Whilst endeavouring to trace the source of the ores in metal- liferous lodes we should bear in mind the experiments of Sand- berger, who found that the heavy metals occur in the silicates of the crystalline rocks of every age. Augite and the magnesia-micas are especially rich, and the lithia-micas are noted as being stan- niferous. ‘The origin of tin-ores is probably different to that of the sulphuretted ores, though both are often best developed at the junction of igneous and sedimentary masyes. This, of course, is partly accounted for by greater facilities for fissuring, and still more by an increase of heat, which is likely to promote the underground circulation, and above all to increase the solvent power of under- ground water. The question of solution has always been a difficult one, and has inclined some people to adopt the notion of sublimation of the metallic sulphides. As an alternative theory we have had the reduction of sulphates by organic agency. But people are begin- ning to think that both these agencies may be dispensed with, and that, under peculiar conditions of heat, pressure, and dissolved gases and salts, the solvent powers of water may be largely increased. Anyhow, it is perfectly certain that metallic sulphides, such as cinnabar and pyrites, are being deposited from hot springs along with various forms of silica, both in California, and at Steamboat Springs in the State of Nevada. We may well believe that this latter place, of which an account was given in the Quarterly Journal of the Geological Society as long ago as 1864, represents with a certain amount of fidelity the conditions which prevailed in the upper portions of the metalliferous lodes of Devon and Cornwall during a period, not of maximum activity, but when a considerable deposit was taking place. The solution and transport of tin-ores are capable of a different explanation. As is well known stanniferous deposits are not only very local, but are also accompanied by a peculiar group of minerals, such as topaz, schorl, axinite, and fluor, which contain a notable quantity of either Fluorine or Boron, and in the case of schorl of both these elements. Daubrée observed that this is the case wherever tin-ore has been found, and he suggested that, in the first instance, tin was brought up from what he calls the general reservoir of the heavy metals as a fluoride. The interesting chemical experiments connected with this ingenious hypothesis are detailed in his great work on Experimental Geology. According to these views stannic-fluoride and steam would decompose each 566— Notices of Memoirs—W. H. Hudleston— other at a moderately high temperature, the result being a deposit of binoxide of tin or cassiterite. The liberated hydrofluoric acid, besides helping to form such minerals as schorl and other fluo-silicates and fluorides, would enter into the general circulation of the rocks, and thus tend to facilitate that kaolinization of the felspars which has produced so much china-clay on the south-west side of Dart- moor, and in the mass of the Hensbarrow granite. It is also worth noting in this connection that, according to Dr. Le Neve Foster, the great flat lode of Carn Brea, near Redruth, is in the main a band of altered rock, and he is inclined to suspect that half the tin-ore in Cornwall is obtained from tabular masses of altered granite. In such cases there is no regular lode, but very fine cracks in the rock have evidently given access to stanniferous solutions, which have deposited oxide of tin more or less abundantly in the vicinity of such cracks, and materially changed the nature of the original granite. The phenomena in connection with these impregnations of tin-ore appear to favour Daubrée’s views; but such points are to be com- mended to the notice of local geologists, who alone can test their suitability to explain the facts which come before them. I would merely remark that too much stress should not be laid on such cases as those of deer’s antlers having been found partly replaced by cassiterite in the old river-gravels. This has been effected at ordinary temperatures, most probably by the aid of alkaline carbonates arising from the atmospheric decomposition of felspars, and proves that the most insoluble minerals may be successfully attacked by agencies now or lately in operation, and their metallic element moved from point to point, but only in very small quantities. It is to be feared that chemical questions such as these possess but little interest for the members of the Association, and I apologize for having introduced them, however briefly, before a general audience. But there are certain conclusions which we are able to draw with- out any special reference to chemistry. In the great metalliferous lodes we see the roots of old mineral springs and geysers, which spouted their water and steam into the air, and perhaps covered the surface of the ground with siliceous sinter. That was a time when the volcanic forces of this remarkable region were on the wane, and after the great outpourings of lava had taken place upon a surface of which every trace, perhaps, has been swept away. How long these hydrothermal agencies continued to be active we cannot tell; but it is by no means improbable that they were in operation throughout a considerable part of Mesozoic time, during which period the spoils of this western land, brought down by the ceaseless forces of denudation, partly found their way into the eastern sea, and thus helped to build up the deposits which were afterwards to be fashioned into the Secondary rocks of England. Reviews—Irving’s Chemical and Physical Studies. 567 Eee ey Sse I.—CuemicaL anD PuysicaL STupIEs In THE METAMORPHISM OF Rocks, BASED ON THE THESIS WRITTEN FOR THE D.Sc. Decrees IN tHE University or Lonpon, 1888. By the Rev. A. Irvine, D.Sc. Lond., Senior Science Master at Wellington College. 8vo. pp. 1388. Price 5s. [August 16, 1889.] HE word “ Metamorphism ” as applied to rocks, in consequence of the various interpretations to which it has been subjected, is no donbt of great service to slippery disputants. By a judicious use of the term some writers can conjure up such a haze as most effectually to elude the pursuit of any critic who rashly endeavours to run them down. Dr. Irving wishes to put an end to this state ' of things by fixing such limitations to the meaning of the term as would, for instance, prevent people from quoting examples of an early stage of ‘‘metamorphism” from such rocks as the Old Red Sandstone Conglomerates of Scotland. In this thesis ‘ metamor- phism” is to be used to mean only changes in the internal structure of rock-masses. The author, however, qualifies this by subsequently stating that he is not dealing with the so-called rocks of the syste- matist, but rather with principles. Hence, he is disposed to ignore the restrictions and limitations which may be convenient in classify- ing rocks; and, as to text-books, they appear to arouse in his breast feelings akin to those of the Knight of La Mancha at the sight of a windmill. In his general conclusion as to the diagenetic origin of the so- called ‘‘ Archean” rocks we are disposed to concur, although it is by no means improbable that many of these rocks may have had a very different and much later origin. But it is by no means certain that the arguments and peculiar nomenclature of the present work will be found, in the sequel, to have strengthened the diage- netic as opposed to the metamorphic theory. No doubt those who can thoroughly understand the book may derive considerable benefit from its perusal. At the same time, the chemical speculations of of this author, as to the earlier stages of rock-genesis, appear by no means equal in quality to those of Sterry Hunt, though this perhaps may be regarded as a matter of fancy, and other readers might arrive at a different conclusion. There is a considerable parade of chemical knowledge brought to bear upon these points. The plan of the treatise is as follows :— Paramorphism, or Mineral Change, includes Primary Paramorphism or Rock Genesis, and Secondary Paramorphism resulting from the gradual alteration of the conditions of rock environment. Metatrophy includes changes in the physical character of the rock-masses, whilst there is no essential change either in the rock-mass or in its con- stituents. Metataxzis is a change of order of the constituents of the rock-mass of which the phenomena of slaty cleavage may be taken as a typical instance. The author then proceeds to deal with what he calls Hyperpheric Change, of which the dolomitization of 568 —— - Reviews— Whitaker's Geology of London. limestones may be taken as an example. There is a section on Contact Metamorphism, which, together with general remarks on Metamorphism, and two Appendices, completes the work. Dr. Irving is a professed disciple of Credner, and has made free use of his writings, as well as of the German literature of the subject generally, nor has he been forgetful of the writings of Hnglish petrographers in the construction of his treatise. In addition to this he combines his own considerable experiences as a geologist in the field and as a chemist in the laboratory. There can be no doubt, therefore, that much interesting and valuable matter is contained in these pages. Moreover, few will disagree with the statement in — the preface that the truest teaching is that which stimulates the mind to active thought, not that which saves the student the trouble of seeking by loading the memory with second-hand knowledge. All this is excellent, but when he talks about a tendency to fetter the discussion of scientific questions by a spurious orthodoxy, Dr. Irving is again tilting at a windmill. The two schools which respectively put their trust in diagenesis and epigenesis enjoy the most perfect freedom of discussion at the Geological Society, and that they make ample use of it any one who is in the habit of attending the meetings can testify. Il.—Tue Gerotocy or Lonpon anp or Part or THE THAMES Vatiey. By Wittiam Waurraxer, B.A., F.R.S. Vol. I. Descriptive Geology, pp. xii. 556, Folding Table. Price 6s. Vol. II. Appendices (Well-sections, etc.), pp. iv. 852. Price ds. Geological Survey Memoir. 8vo. (London, 1889.) EVER before has the geology of any tract of country been described in such detail. We say this advisedly, bearing in mind other publications (the result of private or of official enterprise), whose object has been to describe as fully as possible the geclogy of particular areas. There is good reason why London should yield such ample information, and it is fortunate in having so enthusiastic and so careful an exponent of its geological record. In the country around London there have been more numerous exposures of the strata than elsewhere, in the foundations for houses, not to mention the excavations for gravel, clay, and chalk, and the railway-cuttings. Moreover, not only has the surface structure been revealed in so many places, but the underground geology has been proved in the numerous wells and borings, several of the latter being very deep, and furnishing information of high geological interest. Hence no other part of the world could have contributed such a mass of geological facts. To begin at the end of the work, we may mention that the records of well-sections (given in Vol. IJ.) number nearly 800; and in addition there are notes of numerous trial-holes and many other sections. This volume in itself will be of great practical value to well-sinkers and other engineers; but notwithstanding the mass of information he has so carefully arranged and tabulated, with all authorities indicated, the author still craves for more—asking for Reviews— Whitaker's Geology of London. 569 further information concerning any of the wells, and for records of any new sections. : Turning now to the first volume, we may note that the whole of Middlesex, and parts of Oxfordshire, Bucks, Herts, Hssex, Berks, Surrey and Kent, are included in the country described. It is indeed the tract represented on Sheets 1, 2, and 7 (and northern portions of 6 and 8) of the Geological Survey Map. So far as regards the Chalk and Eocene strata (the description of which occupies about one-half of the volume), the work may be regarded as, in great measure, a new edition of Mr. Whitaker’s Memoir on the Geology of the London Basin (Memoirs Geol. Survey, vol. iv.), although some portions of the area described in that Memoir are outside the limits ~ assigned to the work before us. _ The parts relating to the Glacial Drifts and newer deposits, filling the second half of the volume, are for the most part new, including as they do the description of the beds in the southern portion of Essex. In short, about two-thirds of the entire work may be considered as new. A record of facts, valuable enough in questions of practical geology and as material from which scientific conclusions may be drawn, cannot of course furnish matter which even the most enthusiastic student would care to read steadily through. Details, however, are printed in small type, while general remarks on the more important facts, historical reviews, and conclusions are printed in larger type, These latter will be read with advantage and interest. The author indeed has so exhaustively studied the literature of the subject, that the reader, unless he be anxious to learn in more detail the theoreti- cal views of other workers, need scarcely refer to the previous literature, for Mr. Whitaker has acknowledged all sources of infor- mation. It need hardly be said that the author takes an eminently practical and common-sense view on debateable subjects, and while his remarks are written in a judicial spirit, they are at the same time cheery and not seldom humorous. Students of Mr. Whitaker’s writings are aware that the author has not manifested much liking for purely theoretical or speculative geology, at any rate he has hitherto abstained more than many men with much less experience from expressing theoretical views. But now we are glad to find the author, in dealing with the River Drift, makes the following remarks (p. 829): “ If, however, in the Historical Review of the subject, objection is often taken to the opinions quoted, and my own view is sometimes given in a by no means undecided manner, let it not be put down to the absolute loss of former modesty (and modesty should grow with knowledge) ; but to the fact that one is bound, in the present case, to state one’s own opinion, derived from prolonged study of the beds, and to [avoid] the manifest unfairness of continuing to shelter oneself behind other observers; albeit the shield of Professor Prestwich is used with great advantage.” No one has had the experience possessed by Mr. Whitaker in the area he now describes, and all will be glad to welcome the expression of his opinions. 570 Reviews — Whitaker's Geology of London. Special interest is usually concentrated on debateable subjects, and although certain differences of opinion are maintained on the classification of some of the Hocene divisions, there is little dispute about the position of the beds; the literature of London geology has increased most largely by the discussion of the Thames Valley deposits and their relation to the Glacial epoch. More recently the subject of underground geology has aroused a great deal of attention, for the deeper borings have proved the presence of rocks not pre- viously suspected to occur beneath the area. Special interest may therefore be said to be divided between the Underground Geology and the Pleistocene Geology. The former is becoming more and more a practical subject. Speculations on the behaviour of rocks, especially of Paleeozoic rocks beneath thick accumulations of Secondary strata, are neces- sarily hazardous. Were the whole of the West of England smothered up with Chalk and London Clay (the South Wales Coal-field being exposed), we might know nothing of the Bristol Coal-field, if several deep borings had proved simply Old Red Sandstone in some places and Silurian rocks in others. This up to the present time has been practically the result of deep borings under the London area. Mr. Whitaker gives a full account of all that has been previously written on the plain of older rocks that lies under London. He is careful to point out that there is no evidence of a ridge beneath the area, though it would seem there may be something of the sort northwards, for the older rocks come nearer the surface at Ware than they do beneath London or Harwich. On the subject of most commercial importance he concludes (p. 46) “that Coal-Measures are likely to occur somewhere along the line of the Thames Valley, or in neighbouring tracts; and that those Coal-Measures are likely to yield workable coal. It is rash to attempt to foretell the future; but it seems to me that the day will come when coal will be worked in the South-east of England.” The new boring at Streatham has given further particulars of the presence of the Great Oolite Series beneath the London area, and a full account of this important boring is now for the first time published. By the aid of the many borings, Mr. Whitaker is enabled to dis- cuss’ the underground range of the Jurassic and Cretaceous rocks, and it is somewhat remarkable to learn that there is no certain record of Lower Greensand in the area, though it must underlie the Gault near Risborough. From the Gault there is a gradual passage through the Upper Greensand to the Chalk; and this is an interest- ing fact when we remember that chalky conditions commenced in Gault times at Hunstanton. In the description of the Cretaceous beds, the author acknowledges help from Mr. Jukes-Browne, and some modifications are made in the classification of the zones and rock-beds of the Chalk. Thus the Chalk Rock is assigned an independent position between Middle and Upper Chalk ; the zone of Belemnitella plena is separated from the Melbourn Rock and put with the Lower Chalk; while the lowest Reviews—Whitaker’s Geology of London. 571 zone of the Lower Chalk is termed the zone of Ammoniies varians. Without the aid of these rock-beds but little progress could have been made in mapping the several divisions of the Chalk, for fossils in this, as in other formations, are not always to be found when most wanted. The London Clay has not furnished much material for the believer in definite zones, for the fossils are alike through the formation, although some species are more abundant at certain horizons. Over large areas the London Clay appears to be practically barren of organic remains, indeed Mr. Whitaker mentions that he spent some days in examining new railway-cuttings in the London Clay in Essex, without meeting with any palzontological reward. In dealing with the Hocene strata, Mr. Whitaker speaks of the practical importance of separating deposits that can be mapped distinctly even if there are no great paleontological distinctions in their fossils. This is quite right if we wish to interpret properly the rocky structure of a country, and show the relations of the strata ta the form of the ground. The general remarks on the Lower London Tertiaries, and the full account given of the History and Jiiterature of the subject, are for the most part new. Herein the author criticizes recent observations and views of Mr. Starkie Gardner, Mr. G. F. Harris, and others. The Drifts that irregularly overlie the Bagshot Beds and older strata have given much trouble in determining their respective ages. But the process of minute correlation, which to some minds appears an essential basis for geological happiness, cannot always be carried out; and would lead to much unprofitable anxiety in the matter of Drifts. There may be no paleontological evidence, lithological characters may be of no avail, and; more serious still, there may be no stratigraphical evidence. Hence we can well understand the reason for a chapter on “Deposits of Doubtful Age.” In some instances where outlying patches of gravel occur on London Clay, it is impossible to determine whether or not they are of Pliocene (‘‘pre-Glacial ”) age, whether they are Glacial gravels newer or older than the Boulder-clay, or whether they may have been derived in comparatively recent times (during the denudation of the country) from any one of these accumulations, or from the pebble-beds of Bagshot age. The broad general distinction in the gravels seems to be this. The pebble-beds of Hocene age are almost entirely made up of flint. The “ pre-Glacial ” (and possibly Pliocene) gravels are made up of flint and quartz pebbles. The Glacial gravels contain in addition many pebbles of quartzite, and sometimes derived Jurassic fossils : and they are rudely stratified and sometimes contorted. The River gravels contain all ingredients and are more distinctly stratified. But in Drift deposits there are many exceptions to every rule, and much of the Glacial gravel of Finchley is indistinguishable from the presumably older “ Pebbly Gravel” of the Geological Survey. The Clay-with-flints is also one of the accumulations of Doubtful Age, a residue left during many ages and forming now, by the slow decomposition of Chalk-with-flints by atmospheric actions, leaving 572 Reviews— Whitaker's Geology of London. the flints and earthy matter, together with clayey and loamy material washed from Tertiary strata. The author makes many references to the terms Glacial, post- Glacial and pre-Glacial. The two latter terms (as he says) are inadmissible into schemes of classification from their having no definite significance; but they are conveniently used when our knowledge is very limited that is to say, when we find a bed that is older than Boulder-clay, and which cannot be definitely proved to be Pliocene; or when we find a bed that is newer than Boulder-clay, and yet not definitely Recent. As Mr. Whitaker remarks (p. 328), *“« Beds which are truly post-Glacial in a southern district, may be of the same age as others which are clearly Glacial in a northern one ;” and these remarks apply to the Pleistocene Thames Valley Deposits. We are glad to find that the author supports the view of the fluviatile origin of the Thames Valley gravels and brick-earths. The organic remains indeed clearly support this contention. The diffi- culties raised have béen based on the mode of occurrence of the deposits; but it must be borne in mind that the greater part of the gravel is simply re-deposited Glacial gravel, ready made, and not, perhaps, transported any great distances by the river. In the course of the accumulation of the river-drifts, the river has deepened its channel, leaving terraces in some places at different levels ; but there is no marked regularity in these terraces as we trace the course of the Thames Valley deposits from Maidenhead to London. Following the account of the River Drift, we have a chapter on Alluvium, etc. We should have preferred to divide these subjects into Pleistocene and Recent Alluvial Deposits. It is true that, in the area described, the Alluvium is distinguished from the “ River Drifts” by its fineness of texture, but that is a local feature, for in the higher courses of the Thames and its tributaries we find a good deal of Recent gravel; and Alluvium itself seems entitled to be called ‘River Drift,” as much as the brick-earth and gravel of Pleistocene age. Instructive sections are given of the Alluvium shown in making the Tilbury Docks and in other places. Chapters devoted to Physical Geology and to Keonomic Geology, etc., complete the first volume, and we may call especial attention to the remarks on Springs, Wells, and Water-supply. It is impossible here to enumerate all the matters of interest discussed in the volume, suffice it to say that no subject seems to have been neglected. The work is illustrated by many sections and some pictorial views, and with figures of flint-implements. Lists of fossils are also given. A small coloured index-map would have been useful, but we ought not to make the slightest complaint when we have such a wealth of information in two volumes, bound in cloth, for a total cost of eleven shillings! That London geology excites a good deal of scientific interest apart from its practical bearings, is shown by the large sale of Mr. Whitaker’s Guide to the Geology of London, of which (we understand) a fifth edition has just gone to press, and this is an excellent introduction to the subject treated so fully in the volumes before us. Reviews—Ridsdale’s Cosmic Evolution. 573 IIJ.—Cosmic Evo.xurtion, BEING SPECULATIONS ON THE ORIGIN OF oun Environment. By H. A. Ripspaue, A.R.S.M. 12mo. pp. 130. (London, H. K. Lewis, 1889.) OWADAYS we are considerably ahead of the Hebrew cosmo- gonist in the means for speculating on the origin of our environment; but still there is a large margin of the apparently “unknowable” left for future philosophers to minimize if they can. The recently established doctrine of Evolution favours speculations in this quarter, especially in the minds of those who have received their scientific training since this doctrine has become a faith. The Geological Evolutionist is fortunate in being confined within certain limits both as regards time and space. But it is far otherwise with the Cosmic Evolutionist, who finds his conceptions rendered hazy by an Eternity which had no beginning and can have no end, and by a Space which is equally without limits. No wonder that in such speculations “the imagination” at times “is forced to overstep the safe boundary of reason” (p. 103). This is candid on the part of our author, whose object evidently is to arrive at the truth, so far as that is attainable by the finite mind of man. It is not for us to review the “General Aspect” of Cosmic Evolution any further than by confessing our faith in the grand and philosophic conception of La Place as to the physical history of the Solar system. The author’s inference also seems a fair one, “ that the evolution of present matter from the fire-vapours of the Solar system was analogous to the evolution of the fire-vapours from the universal primordial vapour of all Space.” But we must now leave off playing at “high jinks” in the starry firmament, and stick, as far as we can, to our own planet. The evolution of the primordial forms of matter was doubtless attended with a gradual loss of heat (changed perhaps into planetary motion, since Energy cannot be lost), increase of density and diminution of chemical activity. If this principle is true, there will seem to be an almost unbroken connection between Inorganic and Organic Evolution. Indeed, it might almost be said that “the chemical evolution proceeded till it finally induced an environment wherein favourable forms were matured into Life.” What this chemical evolution is supposed to have been we are told in the first chapter, which may be regarded as a sermon preached upon the text of increase of chemical stability, or, as he puts it, the “survival of the most inert.” ‘This process has been going on from the earliest geological ages, so that “things must have been more lively, chemically speaking, in the Archean period than now!” Moreover, it is probable, he says, that the bodies we call elements are merely arrangements of matter to suit the present environment, and that under different conditions they might be broken up. Change, then, ceaseless change, was the order of things. But the rate was much more rapid in the early stages, whilst, through the gradual survival of the more inert forms, it became slower. It was when this state of physical calm was fairly matured that the forces 574 Reviews—Ridsdale’s Cosmic Evolution. acting in the evolution of Living Forms were first able to come into play. The Organic Aspect of Evolution.—The Harth being now fitted for it, a new and original force came into play; one different in its tendencies and unlike in its action to any of the previously-existing forces of Nature. ‘This force was Lirr. Ever since its first manifes- tation, while Inorganic Evolution has proceeded contemporaneously with it though in a milder and more subdued form, its power and scope of working has steadily increased.” Paleontology, as at present understood, certainly affords no record of that interesting period in the Earth’s history, when the Organic was evolved out of the Inorganic. It is quite in accordance with the author’s general views that such an evolution did take place, although he scarcely ventures to say so. He considers, likewise; that this growth of the Organic out of the Inorganic could only take place at one stage in the development of the Harth, and that, if such a thing were possible now, a serious blow would be struck at the doctrine of Evolution generally. It is most probable that the origin of Life will remain amongst the things unknowable: all that Paleontology can do is to trace the evidence backwards as far as practicable. In this connection some might be disposed to disagree with the author as to the evidence afforded of the alleged approximation of the two branches of life—animal and vegetable. Excluding such doubtful forms as Eozoon, which few now regard as having any connection with organic structure, the earliest certain forms of Life in the Lower Cambrian exhibit a considerable amount of differentiation, rendering it probable that Life had become a factor in the Earth’s history for a considerable period antecedent to this epoch. Hence it is by no means improbable that far more primitive forms existed which may have shown some- thing of the approximation to which the author refers. But where are their remains now? Shall we seek them in the Monian, the Pebidian, or any other of the rival systems, which appear to occupy the ground between the Cambrian and the Archean ? Although quite disposed to agree with the author in his general contention, there are some other statements of his in connection with Paleontology which seem open to criticism. He says (p. 48) that in early times, when the geological forces were more active, that stock had a tendency to survive whose members varied most. In a certain sense this may be so, but the history of the tetra- branchiate Cephalopoda presents us with an instance in the opposite direction. The steady-going Nautilus, though born long before his cousin the ever-changing Ammonite, alone survives. In fact, the author himself (p. 51) observes that a family succumbing either to slow alteration of the environment, or to inter-racial competition, always varies violently during the process. Indeed, the most sluggish genera, such as Lingula, but little affected, perhaps, by the environ- ment, and still less given to inter-racial competition, have been much the same throughout all epochs. In such a case the “ survival of the most inert” is applicable to certain forms of life. But this Reports and Proceedings—G'eological Society of London. 575 does not violate the still higher law, ‘“‘the survival of the fittest” ; it only serves to show that, under certain circumstances, even in the Organic world, the most inert may be the fittest to survive. Whilst: admitting that no force or forces, exactly similar to Life, are known in Nature, Mr. Ridsdale observes, that one or.two of them are not so “utterly unlike as to render it necessary to postulate a supernatural interference with the course of Nature to account for its occurrence.” Certainly, a logical evolutionist need not summon such a Deus ex machina as Creation to account for any phenomenon, even the admittedly obscure one of Life. The author thinks it may be possible in the future to bring yet closer the analogies between the Organic and Inorganic worlds, though up to the present time nothing very conclusive has been pointed out. Perhaps the nearest parallel is that force which determines crystalline structure. A similar idea, it will be remembered, was brought forward in a recent address to the Geological Society. W. H. H. devas Ouse 8S) AN AB) ASNS4@\ SA as DAN SS ee Nov. 6, 1889.—W. T. Blanford, LL.D., F.R.S., President, in the Chair.—The following communications were read :— 1. “Contributions to our Knowledge of the Dinosaurs of the Wealden and the Sauropterygians of the Purbeck and Oxford Clay.” By R. Lydekker, Hsq., B.A., F.G.S. The first section of this paper was devoted to the description of the remains of Iguanodonts from the Wadhurst Clay near Hastings collected by Mr. C. Dawson. They were considered to indicate two species, for which the names Iguanodon hollingtoniensis and I. Fittoni had been proposed in a preliminary notice. In the second section an imperfect metatarsus of a species of Megalosaurus from the Hastings Wealden was described, and shown to indicate a species quite distinct from the one to which a metatarsus from the Wealden of Cuckfield belonged. Two cervical vertebree of a Sauropterygian from the Purbeck of the Isle of Portland were next described, and referred to Cimoliosaurus portlandicus, Owen, sp. The concluding section described an impertect skeleton of a large Pliosaur from the Oxford Clay, in the collection of Mr. A. N. Leeds, which indicated a species intermediate between the typical Kime- ridgian forms and the genus Peloneustes. These specimens were considered as probably referable to Pliosaurus ferow. Evidence was adduced to show that Pliosaurus Evansi, Seeley, should be trans- ferred to Peloneustes. 2. “Notes on a ‘Dumb Fault’ or ‘Wash-out’ found in the Pleasley and Teversall Collieries, Derbyshire.” By J. OC. B. Hendy, Esq. Communicated by the President. The “Top Hard” Seam of the district is being worked in these collieries at a depth of 500 yards, where it has an average thickness of five feet, with a band of cannel in the middle. In the working it was found that the coal began to thicken, until it became double the 576 Reports and Proceedings—Geological Society of London. usual size, the cannel also increasing in the ‘‘'Top Seam,” but in the Lower Seam running out altogether. This double thickness of coal continued till the “ Wash-out” was reached, when both coal and shaly roof disappeared, the space being replaced by sandstone similar to that of the beds overlying the shale. The clay floor of the Lower Seam had not been much interfered with, and this was followed for sixty yards, when the doubly thick seam was again met with, and on being followed gradually assumed its normal thickness. No fossils have been noted in the ‘‘ Wash-out”’ itself, the vertical extension of which is unknown. 3. “On some Paleozoic Ostracods from North America, Wales, and Ireland.” By Prof. T. Rupert Jones, F.R.S., F.G.S. The chief materials referred to were :—- 1. Some good specimens of North-American Ostracoda from the Lower Helderberg and Cincinnati Groups in the British Museum, and the author’s collection ; these have given occasion for a critical revision and careful illustration of several forms. 2. In the ‘Paleontology of New York,’ vol. iii. 1859, several of the Paleozoic Ostracoda of New York State were described but not figured. Copies of some of the original drawings have been courteously supplied, with Dr. James Hall’s permission, by Mr. J. M. Clarke, of Albany. They enlarge our knowledge of the Lower Helderberg fauna. 3. A large collection of Paleozoic Ostracoda, collected in the Lake Champlain district and elsewhere, sent by Prof. R. P. Whitfield, of New York, for examination by the author. 4. Other specimens belonging to the Utica Slate Series from Ontario, presented to the author by Dr John Young. 5. An interesting series of Lower Silurian (Ordovician species from near Welshpool, comprising a characteristic Cincinnati species, sent by Mr. J. Bickerton Morgan. 6. A rare Palzeozoic Cytheroid Ostracod from Kildare, collected by Mr. Joseph Wright, F.G.S. The specimens were described as nearly as possible in the order of their natural relationships and thus, besides adding to the known forms, they were shown to illustrate the modifications exhibited by the genera and species of these minute bivalved Crustaceans, both in limited districts and in different regions. Amongst the forms described were the following new species and variety :—Primitia mundula, Jones, var. cambrica, nov.; P. humilior, sp. nov.; P. Morgani, sp. nov.; P. Ulrichi, sp. nov.; P. Whitfieldi, sp. nov.; Entomis rhomboidea, sp. nov.; Strepula sigmoidalis, sp. nov. ; Beyrichia Halli, sp. nov.; Isochilina lineata, sp. nov.; I. ? jabacea, sp. nov.; Leperditia Claypolei, sp. nov.; Xestoleberis Wrightii, sp. nov. Tue Rey. EH. Tenison Woops.—We regret to record the death of this well-known Australian Geologist, which occurred at Sydney, New South Wales, on the 9th October, 1889. INDEX. ACT ACTION of Frost on Soilcap, 255. —— Pure Water on Mica, 18 Address to the Devonshire Association, 500, 558. ———— Geological Section, 461. Altered Igneous Rocks of Tintagel, 53, IOl. Amblypristis Cheops, from the Eocene of Egypt, 28. America, North, Subaérial Deposits of, 289, 342. Ammonites, Jurassic, 200. Amphibians and Reptiles, Nomencla- ture of, 325. Amygdaloids of the Tynemouth Dyke, 481. Analysis of Fullers Earth, 455, 526. ——— Gault and Greensand, 456. Kentish Rag, 73. Annual General Meeting, Geological Society, 181. Report, Geological Survey of Canada, 130. Archzean Controversy, 319. Arctic Ocean during the Mammoth Period, 305. Ascoceras Murchisoni, Barrande, 121. The Genus, 44. Ashprington Volcanic Series, 332. Attemptto Compute Geological Epochs, 277. Australia, New Silurian Protaster from, 24. AGSHOT Beds and their Strati- graphy, 380. Ballantrae Rocks of South Scotland, 20, 59. Baron, Rev. R., Geology of Madagascar, 234. Barrois, C., Fauna of the Erbray Lime- stone, 276. Index to British Cretaceous Fossils, 35. Bate, C. Spence, Obituary of, 526. Bather, F. A., On a new Genus of Cronoidea from Bavaria, 87; Scien- tific Bibliography, 189; The Basals of Eugeniacrinidze, 239. Baur, G., on Scaphognathus, Newton, 171, 288. DECADE III.—vVOL. VI.—NO. XII. CAN Bavaria, Geological Survey of, 330. Beecher, on the Brachiospongida, 232. Bethesda, North Wales, Lower Cam- brian at, 8. Leyrichia Devonica, Jones, 386. Blake’s Geology of the Country around East Dereham, 87. Blake, F. J., The Genus Ascoceras, 44; The Monian System, 45. Bletchley, Granite at, 356. Blytt, A., Displacement of Beach-lines, ie Bolton, H., Fish Remains from the Coal-Measures, 428. Bonney, Prof. T. G., on Crystalline Rocks of the Alps, 40; The Serpen- tine of the Lizard, 44; Occurrence of a Variety of Picrite in Sark, 109 ; Dyke in the Lizard Serpentine, 189 ; Pebbles in the Cambrian of St. Davids, 315 ; Effects of Pressure on Crystalline Limestone, 483. Breccia and MHornblende-Schist at Housel Cove, 114. Bristow, H. W., Obituary of, 381. Britain, Archzean Controversy in, 319. British Association at Newcastle, 461. Columbia, Glaciation of, 350. . Brontops robustus, Marsh, 99. Brown, H. T., Permian Rocks of Lei- cestershire, 35. Browneichthys ornatus, A. S. Wood- ward, 455. Buckman, S. S., Uniformity of Scien- tific Bibliography, 94; On Jurassic Ammonites, 200; Cotteswold, Mid- ford and Yeovil Sands, 185; The Genus Acanthothyris 329; Descent of Sonninia, and Hammatoceras, 370. Bulletins, Geological Society of France, 329- ALIA PORA, on the Genus, 432. Callaway, Dr. C., Monian System, 94; Secondary Minerals in Crystal- line Rocks, 285 ; The Archzean Con- troversy, 319 ; Foliation in the Mal- vern Hills, 335. Cambrian of St. Davids, Pebbles in the, 15. ene Discovery of Zzurrilepas in, 271. 37 578 CAN Canada, Glaciation of, 211. Carbonia fabulina, var. aitilis, Jones and Kirkby, 270. Carboniferous Gasteropoda, 380. Carter, J., on Fossil Isopoda, 193. Casquets and Rocks of Alderney, 331. Catalogue of Fossil Cephalopoda, 393. —- Fishes, 366. 3 of the British Isles, I. Cervus rectus, Newton, 145. Chalmers, R., Glaciation of Eastern Canada, 211. Champernowne, A., Ashprington Vol- canic Series, 332. orem C., on Lacustrine Deposits, 379. Chapman, F., Foraminifera of the Lon- don Clay, 498. Chelonian Remains from the Wealden, 377: Chemical and Physical Studies in the Metamorphism of Rocks, 567. Chlorite Schists and Greenstones of South Devon, 265. Circumpolar Lands, 305. Clifford’s Richmond Coal-Fieids, Vir- ginia, 138. Sevens Geology of the Cheviot Hills, 6. Clupea vectensts from the Isle of Wight, 40. Coal-plants, British, 457. Coal-seams, Modes of Formation of, 308. — of Western Australia, 240, 432. Coccosteus compared with Homosteus, I. Celonautilus, Muscular Impressions of, 494. Cceluroid Dinosaur from the Wealden, 119. Cole and Jennings, on the Slopes of Cader Idris, 286. Colloid Silica in the Chalk of Berks and Wilts, 237. Comparison of European and American Dinosauria, 204. Cosmic Evolution, 573. Cope, E. D., on the Proboscidea, 438. Creeping of the Soil-cap by Action of Frost, 255. Crick, G. C., on Shell-muscles of Celonautilus, 494. Crick, W. D., and Wilson, Lias Marl- stone of Tilton, 296, 337. Croll, J., Glacial Periods, 140; Rate of Subaerial Denudation, 526. Crystalline Limestone, Pressure on, 483. — Rocks of the Alps, 4o. Index. ECH Cystechinus crassus from Barbadoes, 380, AMES, Dr., on Amblypristis Cheops, 28 ; The Ganoids of the Muschelkalk, 459. Damon, R., Obituary of, 336. Darent Valley, Discovery of Mammoth in the, 113. Davison, C., Uniformity in Scientific Bibliography, 47 ; Secular Straining of the Earth, 220; Creeping of the Soil-cap by Action of Frost, 255 ; Stone-Rivers of the Falkland Islands, 390; on the Mean Rate of Sub- aérial Denudation, 409. Dawson, G. M., Glaciation of British Columbia, 350. —— J. W., Rocks of the Atlantic Coast of Canada, 236. Deciduous Septa of Ascoceras Murchi- sont, 121. Deecke, W., Lias Fish-remains of Alsace, 428. _ Deeley, R. M., on the Boulder Clay in Derby, 224. De Gregorio, A., Note on Pleurotoma turbida, 78. “¢ Dendrodont ” Fishes, 490. Devonian Cephalopoda and Gastero- poda, 29. —— Crustacea, on some, 28. Fossils, 385. Ganoid Onychodus, 499. of South Devon and West Germany, 328. Dinosauria of Europe and America, 204. Dinosaurian Remains, 352, 575- Dipterus macropterus, Traquair, 98. New Species of, 98. Division between the Lias and Oolite, 188. Donald, Miss J., on Carboniferous Gas- teropoda, 380. Drainage of the English Lakes, 150. ‘¢ Dumb-Fault” or ‘‘ Wash-out,” 575. Dyke in the Lizard Serpentine, 189. Dykes and Beds, Local Thickening of, 60. E ARTH’S Crust, Some Physical Changes in the, 49, 115, 165. Earth, Secular Straining of the, 220, 275. Earthquakes, 521. Echinocaris Whidbornei, Jones, 385. ELV Elvans and Volcanic Rocks of Dart- moor, 238. Eocene and Mesozoic Chelonia, 141. Lodiadema granulata, Wilson, 339. Erbray Limestone, Fauna of the, 276. Pena s Fossils of the British Isles, I. Etheridge and Willett, Dentition of Lepidotus maximus, 142. Eugeniacrinidz, the Basals of, 239. Lurycormus grandis, A. 8. Woodward, 449. Exposure of Boulder-clay in Derby, 244. “* Eyes’ of Pyrites, 396. ACETTED Stones of the Salt Range, 415. Falkland Islands, Stone Rivers of the, 390. Felsites of the South-East of Ireland, 545- Fisher, Rev. O., The Beds of the London Area, 48; On the Secular Straining of the Earth, 275. Fishes, British Jurassic, 448. Flint Implements in the Neighbour- hood of Ightham, 142. Foliation in the Malvern Hills, 335. Foord, A. H., on Ascoceras Murchisoni, 121 ; Catalogue of the Fossil Cepha- lopoda, 363; Shell-muscles of Ccelo- nautilus, 494. Formation of Coal-seams, 308. Foraminifera, Bibliography of the, 34. from the London-clay, 498. Forsyth-Major, C., Samos, 431. Fossil Fauna of Sweden, 124. Isopods, 193. Fossils from the Limestones of South Devon, 78. Fouqué, E., on Earthquakes, 521. France, Société géologique de, 238, 320. Fulgurites from Monte Viso, 42. Fullers Earth of Nutfield, 455, 526. Discoveries in ({ARDNER, J. S., Mesozoic Mono- cotyledon, 144. Gault and Greensand, Analysis of, 456. Geikie, Dr. A., History of Volcanic Action, 32. Prof. J., Address to the British Association, 461. Geological Excursion to the Swiss Alps, 250. Index. 579 HUD Geological Society of London, 35, 87, 140, 181, 233, 285, 331), 376, 575: Survey of Bavaria, 330. — Canada, 130, 517. — England and Wales, 86. —_——- ———. — New South Wales, 276. —_————. — Ohio, 48. Geology of Devon, 500, 558. — London, 459, 569. —— — Madagascar, 234. Glacial Geology, 155. Periods, 140. Glaciation of British Columbia, 350. —— — Eastern Canada, 211. Goldfields of Western Australia, 240. Goodchild, J. G., on the Formation of Coal-seams, 308. Granite in a Boring at Bletchley, 356. Graptolites from Dease River, 30. Greenstone and Associated Rocks, 425. Greenstones and Schists of South Devon, 265. —— of Wicklow, 261. Gregory, J. W., on a new Protaster from Australia, 24; on Cystechinus crassus, Gregory, 380. Groom, T. T., A New Form of Tachy- lyte, 45. Growth of Crystals in Igneous Rocks, 90. Hat. Captain Marshall, respondence, 480. Harker, A., The Physics of Meta- morphism, 15 ; Local Thickening of Dykes, 69; ‘‘Eyes” of Pyrites, 396. nee Hatch, Dr. F. H., on Soda Felsites in Wicklow, 70, 288; Petrographical Characters of Rocks from Madagas- car, 235; Notes on the Wicklow Greenstones, 261 ; on Lower Silurian Felsites, 545. Head of Hybodus Delabechei, 427. Hendy, J. C. B., on Dumb Faults, 575. Hicks, Dr. H., on Stexotheca, 288. Hill, Rev. E., Rocks of Alderney, 331. and Jukes-Browne, Colloid Silica, 237. ee angularis, Egerton, 241. History of Tertiary Volcanic Action in Britain, 32. Hof, Lower Paleozoic Rocks of, 411. Hlomosteus compared with Coccosteus, I. Hornblende Schists of the Lizard, 332. Howorth, H. H., on the Mammoth Period, 305. Hudleston, W. H., The Geology of Devon, 500, 558. Cor- 580 HUG Hughes, Prof. T. McKenny, The Lower Cambrian of Bethesda, 8, 96. ae Dr. E., Terrestrial Magnetism, 32 Human Relics found with Bones of Mastodon, 102. Hutchings, W. M., Altered Igneous Rocks, 53, EOI; on Ottrelite in North Cornwall, 214. Hyland, J. S., Dr. on Soda-Microcline, 160; on Zonal Structure in Olivine, 492. Lypsocormus Leedst, A. S. Woodward, 450. tenuzrostris, A. S. Wood- ward, 451. ! CHTHVOSAURUS acutirostris, Zetlandicus, and longifrons, 44. Paddle showing Integuments, 388. Leuanodon Fittont, Lydekker, 354. hollingtoniensis, Lydekker, Index to Cretaceous Fossils of England and Ireland, 35. India, Stones of the Salt Range of, 451. Ireland, Silurian Felsites of the South- East of, 545. Treland, Royal Geological Society of, 187. Irving, Rev. A., on Metamorphism of Rocks, 567. Islands, Notes on the Ponza, 529. ACK’S Mineral Wealth in Queens- land, 226. Jervis, on the Subterranean Treasures of Italy, 174. Johnstone, A., Action of Water on Mica, 187. Johnston-Lavis, Dr. H. J., on Sodalite Trachyte, 74; Notes on the ome Islands, 529. Jones, T. R., Prof. A South en Geologists’ Caen 144; Palzo- zoic Ostracoda, 576. Jones and Kirkby, on the Ostracoda, 269. and Woodward, New Devonian Fossils, 385. Judd, Prof. J. W., Growth of Crystals in Igneous Rocks, 90 ; Tertiary Vol- canoes of the Western Isles of Scot- land, 91; Statical and Dynamical Metamorphism, 243. Jukes-Browne, A. J., Granite at Bletch- ley, 356. Jurassic Ammonites, 200. Clays of Lincolnshire, 334. Index. LYO Jurassic Fishes, 448. Pisolite, 196. J AYSER, E. von, Upper Devonian of Devonshire, 328. Kentish Rag, Analysis of the, 73. Keratophyres, Occurrence of, in Wick- low, 70, 288. Kilimandscharo, Soda-Microcline from, 160. Kilree, J. R., Movements in the Earth’s Crust, 334. Kirkby and Jones, on Ostracoda, 269. [_ACUSTRINE Deposits in Suffolk, ~) . Lake District, Drainage of the, 150. Lamplugh, G. W., Subdivisions of the Speeton Clay, 233. Lapworth, Prof. C., The Ballantrae Rocks of South Scotland, 20, 59; Graptolites from Dease River, 30; Olenedlus Zonein North-West Europe, 190. Leedsichthys problematicus, A. S. Wood- ward, 457. Lepidotus maximus, Dentition of, 142. Lewis, Prof. H. C., Work on Glacial Geology, 155. Lias in South-Eastern Scania, 123. Marlstone of Tilton, 296, 337. Lindstrém, Prof. G., List of Swedish Fossils, 124. Line of Descent of the Invertebrata, 280. List of Fossils from the Marlstone, Tilton, 341. — Papers read before Section C, British Association, 478. Lizard, Breccia and Hornblende Schists at the, 114. Greenstone, 425. Local Thickening of Dykes and Beds by Folding, 69. London Area, Beds of the, 48. Clay, Radiolaria of the, 39. Lower Cambrian of Bethesda, 8. Lydekker, R., Affinities of Five Genera of Mesozoic Reptiles, 39 ; on /chihyo- saurus acutirostris, 44; 2 Coeluroid Dinosaur, 119 ; Eocene and Mesozoic Chelonia, 141 ; a Wooden Dinosaur, 191; Nomenclature of Fossil Reptilia, 325; Wealden and Purbeck Chelonia, 3773; ILchthyosaurus Paddle showing Integuments, 388; Secondary Rep- tilian Remains, 575. Lyons, H. G., on the Bagshot Beds, 380. Index. MAG AGNETISM and Crust, 486, 535. Malton Museum, Paleontology in the, 61. Mewmath Remains Valley, 113. Mansel-Pleydell, J. C., on Aistzonotus angularis, Egerton, 241. Marine Deposits of the Indian Ocean, 514. Marr, J. E., Drainage of the Lake District, 150; Paleozoic Rocks of Bavaria, 411. Marsh, O. C., Restoration of Bronxtops robustus, 99; Comparison of Euro- pean and American Dinosauria, 204. Marshall Hall, Capt., Excursion to the Swiss Alps, 250. Mathtews, G. F., on Stenotheca, 210. McMahon, C. A., on MHornblende Schists, 332. Mean Rate of Subaérial Denudation, 409. Megalosaurus Owent, Lyddeker, 325. Mesozoic Monocotyledon, 144. Strata of Sweden, 124. Reptiles, 39. Were On the Physics of, 15, 96. -———— Statical and Dynamical, 243. Microscopic Fauna of Cracow, 328. == ——_ sities oF jmegsic Pisolite, 196. Morberg, J. C., Lias in South-Eastern Scania, 123. Monian System, 45, 94. Murray, Dr. J., Marine Deposits in the Indian Ocean, 514. the Earth’s in the Darent NAZ2LES, Sodalite Trachyte dis- covered in, 74. Naumann, E., Terrestrial Magnetism, 486, 535. Neumayr, M., Descent of the Inverte- brata, 280. New South Wales, Geological Survey of, 276. Species of Fossil Isopod, 193. Newton, E. T., on Clupea vectensis, Newton, 40; Vertebrate Fauna of Norfolk Forest Bed, 145; New Dinosaurian Remains, 352. on Pterosauria, 171, 288. Nicholson, Prof. H. A., on Syringolites Roeneria, 432. Nodular Felstones from the Lleyn Peninsula, 186. Nomenclature of Fossil Reptiles, 429. Northampten, The Middle Lias of, 420. ° Nova Scotia, Ostracoda from, 269. 581 PON ()BITUARY of C. Spence Bate, 526; H. W. Bristow, 381; R. Damon, 336; Rev. E. Tenison Woods, 576. Occurrence of Radiolarians in Creta- ceous Strata, 30. — — Soda-Felsites in Wick- low, 70, 288. Olenellus Zone in North-West Europe, 190. i Olivine, Zonal Structure of, 492. Onychodus in Spitzbergen, 499. Origin of Movements in the Earth’s Crust, 334. Orinosaurus capensis, Lydekker, 353. Ornithopsis, Note on the Pelvis of, 2378 Ostracoda from Nova Scotia, 269. Ostracoda, Paleeozoic, 576. Ottrelite in North Cormmwall, 214. Pavors of Lchthyosaurus showing Integuments, 388. Palichthyology, Dr. K. von Zittel, on, 125, 177, 227. Palega McCoy, Carter, 195. Paleontological Discoveries in Samos, 431. Record, A, 381. Palezeontology in the Malton Museum, 361. Paleeozoic Rocks of the Fichtelgebirge, All, Paros, Marble Quarries of the Isle of, 28. Pavlow, A., Jurassic and Cretaceous Rocks of Russia, 520. Pebbles in the Cambrian of St. Davids, 315. Pebbly Sands of Suffolk, 377. Pelorosaurus armatus, Lydekker, 325. Permian Rocks of the Leicestershire Coal-field, 35. Petrographical Characters of Rocks of Madagascar, 235. Phillipsastrea, @Orb., On, 398. Physical Changes in the Earth’s Crust, 49, 115, 165. Physics of Metamorphism, 15, 96. Physiography of the Lower Trias, 549. Picrite, A Variety of, in Sark, 109. Pinna Fittonensis, Wilson, 338. Place in the Sequence of Ballantrae Rocks, 20, 59. Pleistocene Boulder Clay in Derby, 244. Pleurotoma turbida and P. colon, Note on, 78. Polyzoa from the Inferior Oolite of Dorset, 239. Ponza Islands, Notes on the, 529. 582 PRE Preglacial Forest Bed, 145. Pressure on Crystalline Limestone, 483. Prestwich, Prof. J.. Remains of Mam- moth in the Darent Valley, 113; Palzolithic Implement at Ightham, ~ 142; Pebbly Sands of Suffolk, 377. Proboscidea, On the, 438. Proposals Concerning a Survey, 486. Protaster brisingoides, Gregory, 24. Pterosauria, E. T. Newton on the, 171. Ptychacanthus and Tristychitus, 27. Magnetic UEENSLAND, Mineral Wealth in, 226. AISIN, Miss C. A., Some Nodular Felstones, 186 ; Greenstones and Schists of South Devon, 265. Reade, T. Mellard, on the Physio- graphy of the Lower Trias, 549. Relation between Syrzngolites and Roe- meria, 432. Report of the Geological Survey of Ohio, 48. Reptilian Remains, 575. Restoration of SLvoztops Marsh, 99. Review of the Mesozoic Formations of Sweden, 124. Reynolds’s Geological Atlas, 523 ; Map of the Environs of London, 525. Rhinobatus bugesiacus, Note on, 393. Richmond Coal-Fields, Virginia, 138. Ricketts, Dr. C., Physical Changes in the Earth’s Crust, 49, 115, 165. Ridsdale, E. A., on Cosmic Evolution, robustius, 573: Rocks of the Atlantic Coast of Canada, 236. Roberts, T., on Jurassic Clays, 334. Royal Geological Society of Ireland, 187. Russell, I. C., Subaérial Deposits of North America, 289, 342. Russia, Secondary Rocks of, 520. Riist, Dr., on Cretaceous Radiolarians, So. Rutley, F., on Fulgurites from Monte Viso, 42; Tachylyte from near Glasgow, 379. GANFORD, P. G., Analysis of the Kentish Rag, 73; Analysis of Fullers Earth of Nutfield, 455, 526 ; Analysis of Gault and Greensand, 456. Index. SWI Sehet Dr. R., on Phillipsastrea, 399. and Woodward, Palzonto- logical Record, 381. Scientific Bibliography, 189. Uniformity in, 47, 93> 94- Scyelite, Occurrence of, in Sark, 109. Secondary Mineral in Crystalline Rocks, 285. Secular Straining of the Earth, 220, 275. Seeley, Prof. H. G., on the Pelvis of Ornithopsis, 237. Selachian Fish from the Lithographic Stone, 393. Serpentine of the Lizard, 44, 94. Shell-muscles of Calonautilus, 494. Sheppy, Foraminifera from, 498. Sherborn, C. D., Bibliography of the Foraminifera, 34; Uniformity in Scientific Bibliography, 93; Fora- minifera of the London Clay, 498. Shrubsole, W. H., Radiolaria of the London Clay, 39. Silurian Sponges, 232. Protaster from Australia, 24. Slopes of Cader Idris, 286. Société géologique de France, 238. Soda-Microcline from Kilimandscharo, 160, Sodalite Trachyte discovered in Naples, 74- Somervail, A., Serpentine of the Lizard, 96; on Breccia and Hornblende- Schists, 114; Greenstone of the Lizard, 425. Sonninia and Hammatoceras, Descent of, 370. South African Geologists’ Association, 144. Speeton Clay, Subdivisions of, 233. Statical and Dynamical Metamorphism, 243. Stenotheca, Second Note on, 210, 288. Stone, G. H., on Stones from the Salt Range, 415. Stone Rivers of the Falkland Islands, 390. Streatham, On a Deep Boring at, 38. Stur, D., on British Coal Plants, 457. Subaérial Denudation, 409. Deposits of North America, 289, 342. Subterranean Treasures of Italy, 174. Swan, R., Marble Quarries of Paros, 528. Swanage, Histionotus angularis from, 241. Swiss Alps, Geological Excursion to the, 250. Index. SYS Systematic Position of the ‘* Dendro- dont” Fishes, 490. ACHYLYTE Gabbro, 43. associated with — from Victoria Park, Glasgow, 379. Teall, J. J. H., Amygdaloids of the Tynemouth Dyke, 481. Tertiary Volcanoes of Scotland, 91. Terrestrial Magnetism, 326, 535. Thompson, B. M., Lias of North- ampton, 429. Tin and Coal in Western Australia, 432. Tintagel, Altered Igneous Rocks of, 53, LOL. Traquair, Dr. R. H., on Homosteus com- pared with Coccosteus, 1; on Tristy- chius and Ptychacanthus, 27; a New Species of Dipterus, 98; on ‘* Den- drodont” Fishes, 490. Trias, Physiography of the Lower, 549. Triassic Ganoids, 459. Trigonocrinus, a New Genus of Crinoidea, $7. Tristychius and Ptychacanthus, Notes on the Genera, 27. Turrilepas Canadensis, H. Woodward, 274. in the Utica Formation of Canada, 271. Tynemouth Dyke, Amygdaloids of the, 481. PHAM, W., on the Work of Prof. H. C. Lewis, 153. ERTEBRATE Fauna of the Nor- folk Forest-Bed, 145. 583 ZON \\V/ ALFORD, E. A., Polyzoa from Inferior Oolite, 239. Walker, F. J., on Oolitic Brachiopoda, 329. Wealden, a Cceluroid Dinosaur from the, 119. Wethered, E., on Jurassic Pisolite, 196. Whidborne, Rev. G. F., Devonian Crustacea, 28 ; on Devonian Cepha- lopeds, etc., 29; Fossils of the Limestones of South Devon, 78. Whitaker, W., Deep Boring at Streat- ham, 38; Geology of London and part of the Thames Valley, 568. Whiteaves, J. F., Canadian Paleeonto- logy, 517. Wicklow Greenstones, 261. Wilson and Crick, Lias Marlstone of Tilton, 296, 337. Wisniowski on the White Jura of Cracow, 328. Wooden Dinosaur, 191. Woodward, A. S., Palzeontology in the Malton Museum, 361 ; Catalogue of Fossil Fishes, 366 ; on Rhznobatus bugestacus, 393; Hybodus Delabechet, 427 ; on British Jurassic Fishes, 448 ; on the Devonian Ganoid Oxychodus, 499- — Henry, Discovery of Zur- rilepas in Canada, 271. P., Coal and Tin in iiesiow Australia, 432. Woodwardian Museum Notes, 396. Woods, Rey. E. Tenison, Death of, 576. Worth, R. N., Volcanic Rocks of Dartmoor, 238. ORKSHIRE Philosophical Society, 329. ITTEL, Dr. K. von, on Palichthy- ology, 125, 177, 227. Zonal Structure of Olivine, 492. Se STEPHEN AUSTIN AND SONS, PRINTERS, HERTFORD. aise ey oe } Ae y Fy = ‘ a4 Py Ve ’ 1 x . pay i ‘ t . . aX iL 3 F vAEIN i . ‘ 6 3 Me g 40ST eS SS ve ¥ f Ss. 7 rie i wag i 5 1 7 \ h a“ ¢ f 2 £ i ‘ F 1 ee aos a: { . = ty < vA = Ls 1 Set a. 3 = x A. bi 3 a “3 ~ f i re ae sy A 3 9088 01366 677