Op PALEONTOGRAPHICAL SOCIETY.

i VOL. XVI
CRETACEOUS

ECHINODERMAT A.

t a ih Vou. I, Parr I.

TRILOBITES

OF THE

SILURIAN, DEVONIAN, ETC., FORMATIONS. |
Parr J, DEVONIAN. |

FOSSIL BRACHIOPODA.

a Vou. III, Parr VI, No. 1.
ie '

| DEVONIAN.

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. EOCENE MOLLUSGCA.
an:

cf mi Part IV, No. 2.
—e Pee TT wens
_ RE PPT LEA
i 4133 OF THE

SUPPLEMENT No. II, CRETACEOUS.

CRETACEOUS AND WEALDEN FORMATIONS. -
SUPPLEMENT No. III, WEALDEN.

IssvED For 1862.

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A MONOGRAPH

ON THE

Baer tsH FOSS 1 L

ECHINODERMATA

FROM

THE CRETACEOUS FORMATIONS.

BY

THOMAS WRIGHT, M.D., F.R.S. Enry., F.G.S.,

CORRESPONDING MEMBER OF THE ROYAL SOCIETY OF SCIENCES OF LIEGE,
AND SENIOR SURGEON TO THE CHELTENHAM HOSPITAL,

‘VOLUME FIRST.

PART FIRST.
ON THE CIDARIDA.

LONDON:
PRINTED FOR THE PALZONTOGRAPHICAL SOCIETY.
1864.

J. E. ADLARD, PRINTER, BARTHOLOMEW CLOSE.

A MONOGRAPH

ON THE

CRETACEOUS ECHINODERMATA.

ON THE CRETACEOUS GROUP.

Tue Cretaceous group, as a whole, as developed in England, has been so fully
described by Conybeare and Phillips,’ and its subdivisions by other authors,” that it
appears to be unnecessary to devote any great space to this branch of the subject, beyond
an epitomized outline of the subdivisions of the Cretaceous. rocks, with brief notes on the
species of Hchimide found therein, and the co-relation of these stages with their equivalent
zones of life in the Cretaceous systems of the Continent of Europe; and as the Isle of
Wight exhibits some of the -best-coast-sections of the Cretaceous rocks in the British

' The ‘Outlines of the Geology of England and Wales’ contains a most able account of this formation.

2 The following, among many others, may be consulted fer important information on the Cretaceous
formation :—Dr. Fitton’s various memoirs in the ‘Geol. Transactions,’ and ‘ Quarterly Journal of the Geol.
Soc. ;’ Sir H. De La Beche, “ On the Chalk and Greensand of Lyme Regis,” ‘Geol. Trans.,’ vol. ii; Young
and Bird and Professor John Phillips on the Geology of Yorkshire; Dr. Mantell’s works on the
Geology of Sussex; Samuel Woodward’s ‘Geology of Norfolk ;? Dixon’s ‘ Geology of Sussex.’ The various
memoirs in the ‘ Quarterly Journal of the Geol. Soc.’ on the Cretaceous Rocks, by Professor E. Forbes,
Messrs. Lonsdale, Rose, Austen, Cunnington, Morris, Weaver, Rose, Clarke, Bunbury, Bowerbank,
- B.C. Taylor, Ibbetson, Toulmin Smith, D. Sharpe. The Manuals of Geology, by Sir H. De La Beche,
Sir Charles Lyell, and Professor Jukes; and the “ Geology of the Isle of Wight,” by Mr. H. W. Bristow,
in the ‘Memoirs of the Geological Survey.’ The reader will likewise find most valuable information
in Le Vicomte D’Archiac’s ‘ Histoire des Progrés de la Géologie,’ tom. iv and v, “Sur la Formation
Crétacée ;” the memoirs by M. E. Guéranger, in the ‘Bull. Soc. Géol. de France;’ M. Cornuel’s
‘«Section of the Environs of Vassy”’ (‘ Mém. Soc. Geol. de France,’ t. iv) ; M. Leymerie’s ‘‘ Memoir on
the Department of the Aube’’ (‘Mem. Soc, Géol. de France,’ t. ivand v); and in the different important
works by the late M. Alcide d’Orbigny.

al

2 CRETACEOUS GROUP.

Islands, in their stratigraphical order of superposition, I shall take these as a type of the
whole, supplying any deficiency in the series by examples afforded by other localities.

THE LOWER GREENSAND.

The Lower Greensand, occupies an extensive tract in the southern part of the Isle of
Wight, where it attains a thickness of nearly 900 feet; this great formation has been so
carefully examined and well described by the late Dr. Fitton,’ in his stratigraphical
account of the section from Atherfield to Rocken End, on the south-west coast of the
island, that 1 must refer the reader for full information te that valuable memoir for further
details. Having worked several times over all the beds of that remarkable and most in-
structive district, and in my excursions had the advantage of the local knowledge and
assistance of Dr. Fitton’s collector and guide,’ I shall now merely attempt a generalized
account of this section, for the purpose of pointing out the beds with which we are more
immediately interested, in our description of the Echinidze contained therein.

The entire series of the Lower Greensand beds, 809 feet in thickness, rise in succes-
sion from the shore and ascend into the cliffs between Atherfield Point and Rocken End,
towards which they dip at an inclination of about 2°.

The following Subdivision of the Atherfield Section was proposed by Dr. Fitton, in

ascending order.
Feet. Inches.

Mag ETNA ACN Ct NE soc cg ot sniss Se val os do's vo gute eden uc 5 3
DE MCRAE TONERS) wai cr cx che Maar toe vg, shin «Pee Seams erasers pe cod snk 60 0
lee PTET EMEC T ERIC oe ees oes cine, inna tne dé See Henna ane 85 0
IV. The Lower Gryphea Group ..................cceccccee eee 32 0
We Soopbes |G tonp igs. } 2 sh dokin. ntews ie ee 50 4
BL, dio wer. Criaceran Gao: «sso saws ove tis cwady «douse ds vende 16 3
Wit, “Walpen Clays and Sands) 2... ....565.is.0-.seos voands crests 57 0
WHE Wp per*Orioceras Grotip’ oo)... oo. ee ccc ose nas 46 2
IX. Walpen and Ladder Sands (1.0.2.0... ccs cece cee ne eee 42 0
x Upper Gryphes Growy .! 2.6 0 Ee 16 0

MOE. F OMEMETING MAS. .'S: SoS I A ele 20 0.
aad: Toliated (Clay wad Sand .ce) i... A 25 0
XIII: Sands of Walpen and Black-Gang Undercliff ......... 97 0
XIV. Ferruginous Sands of Black-Gang Chine............... 20: 6
XV. Upper Clays and Sand-Rock................0....cceeeeees 118 0
ev.) aioe Snrrds He Ohya... cence 118 4
808 10

1 “ A Stratigraphical Account of the Section from Atherfield to Rocken End, in the South-west Coast of
the Isle of Wight,” ‘Jour. of the Geol. Soc.’ vol. iii, p. 289, 1847.
_? Mr. Charles Wheeler, fisherman, at Ventnor, is the person alluded to, he has a most correct know-
ledge of the range and position of all the beds, and of their fossil contents, and is a most trustworthy
guide to the Atherfield Section.

LOWER GREENSAND. 3

I. The Perna beds, which here form the base of the Lower Greensand, rest upon
Weald clay; the junction between the lacustrine series of the latter with the marine
deposits of the former exhibit no trace of disturbance ; a thin seam of bone-bed, composed
of the teeth of fish of lacustrine species, attest a change of conditions similar to that
observed in some junction-beds in other formations, as between the Upper Keuper and the
Lias, and the Upper Silurian and Devonian series. This junction, which is only sometimes
visible, occupies about eight inches of vertical thickness; on one occasion I succeeded
in detaching a block of rock, about a foot thick, from the beds, the lower half of
which contained the lacustrine shells of the Weald clay, whilst in the upper half Perna
Mulleti, Desh., Exogyra sinuata, Sow., and other Lower Greensand shells, were found.
The Perna beds rise from the base of the cliff, at a point a few yards to the east of the
flag-staff of the coastguard-station ; they consist of dark-blue sandy clay and greenish
sand, forming in parts a very hard rock, and characterized by that remarkable shell Perna
Mulleti, Desh., which is not found in any other bed in the section. Nearly one hundred
species of marine shells are found in the Perna beds; among these Wautilus Requinianus,
dOrb., and Hvogyra sinuata, Sow., appear for the first time, of very large size, and
Hemipneustes Fittonvi, Forb., among the Echinida, with the remains of fish belonging to
the genera Zamna, Odontaspis, Saurocephalus, Hybodus, &e.

Il. The Atherfield Clay is of a drab colour, passing into bluish-gray, and contains
flat nodular masses. Ammonites Deshayesii, Leym., Pinna Robinaldina, dOrb., and several
other species of Conchifera, with the bones of a Turtle, and the remains of Hchinide, are
found in this bed.

Ill. Zhe Crackers, so called from the noise produced by the waves dashing over the
ledges formed by these rocks on the shore, are the most interesting fossiliferous group of
the entire series, and consist of alternations of sandy clays and clays, and two layers of
ferruginous sandy nodules. All the clays resemble Fullers’ earth, and the sand between
the nodular concretions in the lower bed is sometimes indurated into an imperfect stone.
The lower part of this group is a brown clay and sand, called the Lower Lobster bed, from
the number of Astacus Vectensis, Bell, found therein; the succeeding beds are sands,
containing concretionary masses of sandstone full of beautiful fossil shells, Ammonites
Deshayesii, Leym., Pholadomya Martini, Forb., Myacites plicata, Sow., Corbula striatula,
Sow., and several other Conchifera. Many of the M/yadz@ are found in the upright position
they assumed during life. ‘The lower sandstone, from a foot to eighteen inches in thick-
ness, is almost entirely made up of Gervillia aviculoides, Sow., Trigonia Dedalea, Park.,
Ammonites Deshayesii, Leym., and other shells. ‘The upper layer of sandstone contains
coniferous wood and a Zeredo, and the upper clays are fossiliferous throughout. In the
concretionary nodules of the lower series of this group I have collected Pseudodiadema
Autissodorense, Cott., P. Ibbetsoni, Forb., and Hemipneustes Fittoni, Forb., with the

4 LOWER GREENSAND.

beautiful winged shells Rostellaria glabra, Forb., R. retusa, Sow., Pterocera Fittoni,
Forb., and several species of Cerithia, as Cerithium turriculatum, Forb., C. Neocomiense,

d’Orb., and C. Phillipsi, Leym.

IV. The Lower Gryphea or Exogyra Group has for its base a thick bed of ferrugi-
nous sand, overlain by sand containing Perna aleformis, Sow., and Terebratula sella, Sow.,
in great abundance, in thin seams of sand. The zones with Exogyra sinuata, Sow., which
here are very large, are found in the upper part of the group.

V. Zhe Scaphites Group forms three beds; the lowest is composed of brown ferru-
ginous sand, containing Lvogyra sinuata, Sow., Terebratula sella, Sow., Rhynchonella
Gibbsiana, Sow.; and of the Echinide I found Cardiaster Benstedi, Forb., and Nucleolites
Olfersii, Ag.; the middle beds, about two feet in thickness, contain layers of nodules
enclosing Scaphites gigas, Sow., and Scaphites Hillsii, Sow.; the upper consist of thick
beds of greenish sand, containing, in the upper part, fine large specimens of Hzogyra
sinuata, Sow.

VI. Zhe Lower Crioceras Group consists of ranges of large sandy nodules, enclosing
Crioceras Bowerbankii, Sow. ; the lowest range rises on the west of Whale Chine, and is
succeeded by two other ranges, all three enclosed in sand about nine feet thick; the
lowest, furnishing the best fossils, passes the bottom of Whale. Chine, from whence I
have obtained several large specimens.

VII. Zhe Walpen and Ladder Sands and Clay extend from the east of Walpen to half
way between Ladder and Whale Chines, where they are well seen; the lower half of this
group contains Ammonites Martini, d’Orb., and a large Gryphea; the upper half,
which is clayey below and sandy above, contains Dentalium, Myacites mandibula, Sow.,
Pinna Robinaldina, V Orb.

VIII. The Upper Crioceras Group consists of sandy nodules imbedded in sand, and
contains Crioceras Bowerbankii, Sow., Ammonites Martini, d@Orb., Gervillia solenoides,
Defr., Zerebratula sella, Sow., and several other shells. This group is seen for some
distance along the shore east of Walpen Chine, which is crossed by it, as are also Ladder
and Whale Chines.

IX. The Walpen and Ladder Sands consist of greenish and gray sand, with a layer
of large fossiliferous nodules at the base, containing Serpule, Thetis, Gervillia, Cucullea,

Corbula, and other shells, together with an Urchin belonging to the genus Brissus,

X. The Second Gryphaa or Exogyra Group.—The lower part of this group consists of

LOWER GREENSAND. 5

sand and clay containing small nodules enclosing a Brissus, Ammonites Martini, dV Orb.,
and detached valves of Hxogyra sinuata; above are three or four ranges of Lvxogyra
sinuata, Sow.; the parallel edges of these large shells, as seen in the cliff, indicate three or
four continuous strata, with irregular clusters between them. ‘The second or upper
Gryphea group appears at low water at Shanklin, where the several ranges of Hxogyre
are seen rising beneath each other. Varieties of this shell appear to me to charac-
terize different beds; for example, the specimens of Hvogyre from the Crackers and
Lower Gryphza group. present. marked differences when compared with shells of the
same species from the Upper Gryphea group. A similar observation has been made by
M. Cornuel on the Lvxogyre. collected by him near Vassy, in France. This geologist
assured Dr. Fitton ‘that he could at once assign each variety of form to a special place
in the section of that vicinity.”” Small fragments of vegetable remains (Louchopteris
Mantellii, Brong.) occur not only im these beds, but nearly throughout the entire
formation.

XI. The Chff-End Sands consist of uniform sand about fourteen feet thick, with a
subordinate bed of fossiliferous clay containing Zrigonia Dedalea, Park., in the lower part,
and plant-like pyritiferous concretions.in sand and clay in the upper part.

XII. Foliated Clay and Sand.—Consist of alternations of dark-blue clay and greenish,
translucent, siliceous sand, containing nodules of pyrites and large irregular masses of
coarse sandstone. These beds are well seen in Walpen. and Black-Gang Chines, but no
fossils have hitherto been found in them.

XIII. Sands of Walpen and Black-Gang Underclif{—This group commences with
a bed, about ten feet in thickness, of loose white sand, with thin lamine of gray clay ;
this is succeeded by seventy feet of greenish and brownish sand overlain by seven
feet of coarse ferruginous sand, with rounded grains of iron-ore in the lower half of
the bed, and by twelve-feet of alternating sand and clay, making a total of 100 feet.
There are only very few fossils in this group—Myacites plicata, Sow., and MM. man-
dibulata, Sow.

XIV. Zhe Ferruginous Bands of Black-Gang Chine rise from the shore between Rocken
End and Black-Gang Chine, and form the uppermost fossiliferous group of the Lower
Greensand ; they are composed of brown and yellow sand, with layers of ferruginous
concretions, overlain by a bed of ferruginous sandstone, about five feet in thickness; the
group is about twenty feet in all, and is the equivalent of the zone of Lower Greensand at
Parham Park, and other places in Sussex, and near Sandgate in Kent. The sands in this
group are fossiliferous throughout, and the species identical with those found in the Perna
bed and Cracker rocks at the bottom of the section.

6 GAULT.

XV. The Upper Clays and Sand Rock consist of forty feet of dark clay with pyrites,
separated by eighteen feet of white and green-coloured sand from a mass of clays and
sands sixty feet thick. The bed 47 of this group is dug near Rocken End for the
manufacture of glass; it contains no fossils.

XVI. Various Sands and Clay constitute the remainder of the section; they measure
about 120 feet in thickness, and are overlain by the Gault.

The Lower Greensand represents the upper portion of the rocks known as the
Terrain Néocomien of MM. Thurmann and d’Orbigny ; Terrain Jurassique supérieur of M.
Mathéron ; Couches adossées au Jura of Von Buch; Formation Waldienne et Néocomienne
of MM. Dufrénoy and Elie de Beaumont; Calcaire & Spatangues, I Argile ostréene, of
M. Cornuel; Argiles tégulines et grés vert and “ Terrain Néocomien” (Wealden) of M.
Leymerie. The French geologists consider the Wealden clay and Hastings sand as the
inferior, and the Lower Greensand the superior, portion of their Véocomien, whilst English
geologists describe the Wealden and Lower Greensand as distinct formations.

THE GAULT.

In several coast-sections the Gault is seen separating the Lower from the Upper
Greensand ; this bed of dark clay is called “the blue slipper,” from the tendency of the
overlying strata to form landslips by gliding over its surface. ‘The charming scenery of
the Undercliff has been in a great measure produced by the foundering of the Upper
Greensand and Cretaceous rocks over the Gault clay ; the rain-water having saturated these
porous beds, bursts forth in springs, which wet the surface of the clay, and occasions
slips of the superincumbent strata. A rich fertile soil is thus formed upon a broad terrace
of stiff clay, exposed to the south, and sheltered from the north by a high mural
escarpment of Upper Greensand. Under these favourable physical conditions vegetation
springs up in great luxuriance, on a natural terrace high above the sea, producing a
coast-scene unequalled in beauty in the British Isles.

The Gault is about 100 feet in thickness, and in the Isle of Wight contains few fossils,
as Inoceramus sulcatus, Sow., and J. concentricus, Sow. ; near Folkstone and Charmouth it
has yielded many beautiful shells in high preservation. I shall figure some rare Hchinide
from this bed at Folkstone. '

The Red Chalk is a remarkable stratum, supposed to be the equivalent of the Gault ;
it is limited both in thickness and extent, for if we take, says the Rev. T. Wiltshire, one
hundred feet as its maximum and four feet as its minimum thickness, and 100 miles as its
extreme length, we shall not be far from the truth. Itis said to be peculiar to the English
Chalk. It is well exposed at Speeton, near Filey, on the Yorkshire coast, and at Hunstanton
Cliff, near Lynn, Norfolk ; in both localities it is a red calcareous rock, deeply coloured by

RED CHALK. 7

the peroxide of iro, and containing minute siliceous grains, and small pebbles of chal-
cedony, quartz, flint, &. This rock from Hunstanton yielded by analysis carbonate of
lime, with a little alumina, 82°3; peroxide of iron, 6:4; silica, 11°3 = ; 100.

Hunstanton Cliff" of which the annexed woodcut gives an idea, consists of five
different beds—l1st, the uppermost, or white chalk, is forty feet thick; 2nd, bright-red
chalk, four feet ; 3rd, yellow sandy bed, ten feet; 4th, a dark brown pebbly stratum, forty
feet ; and 5th, a dark-coloured bed, almost black, twenty feet.

These divisions at Hunstanton, the Rev. 'T’. Wiltshire states, do not run into each other,
but are quite distinct; the red chalk is as clearly separated from the white as though thie
one had been covered by a broad band of paint, and the same remark holds true of the others.
When the sun shines upon the cliff, and lights up the bright white, bright red, the pale
yellow, and the dark brown and black, and casts a shadow over the mass of gaily tinted
materials at the base, a picture is produced not easy to be surpassed in beauty, and
certainly not to be fully appreciated unless it is seen.

The Red Chalk is very fossiliferous, containing Ammonites, Belemnites, Brachiopoda,
Echinide, and Corals.

In compliance with my request, my friend the Rev. T. Wiltshire, F.G.S. has kindly
sent me the following note, embodying his latest observations on the Red Chalk at Speeton.?

“Tn answer to your inquiry respecting the natural section of the Red Chalk at the

1 For ample details, see the Rev. Thos. Wiltshire, on the ‘Red Chalk of England.’
2 To this gentleman’s kindness I am likewise indebted for the above woodcut, copied from a water-

colour drawing in his collection.

8 SPEETON CLAY.

most northern extremity of that bed im England, viz., in the neighbourhood of the little
Yorkshire village of Speeton, I send you a few scanty notes. On my first visit to
Speeton, some years since, I imagined, as I subsequently described in the second volume
of the ‘ Geologist Magazine,’ and in the ‘ Proceedings of the Geologists’ Association’ for
1859, that the Red Chalk in Yorkshire consists of a couple of bands of a highly coloured
marl, of about thirty feet in thickness from top to bottom, and that its fossils are of such
forms as to imply aclose relationship with Gault species. This opinion I derived from seeing
the section in a gulley to the east of the village; but subsequent investigations made upon
the shore under the cliff, at a mile or more from the ravine, showed me that my former ob-
servations were slightly incorrect, and that the Red Chalk, in that part of Yorkshire at least,
contains two more additional coloured bands, and that its total thickness from top to bottom
is not less than 100 feet, and that its upper portion belongs to the Lower Chalk series.
“The highest bed of Red Chalk at Speeton may be seen rising from the beach at a
very gentle inclination, at about a mile and a half to the south-east of the gulley. This
bed, which is of varying thickness throughout its course, may be estimated as being on
an average about five feet thick; it is of a pale pink colour, very hard, and presents a
strongly marked appearance from the white chalk, above and below, with which it
is in contact. The fossils found in it are Rhynchonella Mantelliana, Gryphea vesicu-
laris, Discoidea cylindrica, Holaster subglobosus, Spines of Cidaris, Spines of Diadema
small vertebrae and teeth, together with a considerable number of Zerebratuline graciles.
Above this bed, in the white chalk, are found Holaster subglobosus and Ammonites
peramplus. 'Yhe pink band just mentioned is followed by a greenish-yellow chalk, about
forty feet thick, almost destitute of organic remains, except fragments of Jzocerami, and
marked by numerous thin layers of marl, not unlike those met with in the Lower Chalk of
Sussex. The next bed in descending order is one of a light pink colour, about three feet in
thickness, likewise destitute of fossils, with the exception of fragments of Znoceram?. This
is followed by another stratum of greenish-yellow chalk, about nine feet thick, containing
small Gryphee, and Terebratule semiglobose, and Peltastes, but, like the two preceding
beds, generally unfossiliferous. The greenish-yellow chalk is succeeded by five feet of
white and red chalk, in thin bands, very deficient in organic remains, and this rests
upon a pale-red band, about seven feet thick. In the upper part of this last seven feet
of red material are many Vermicularie umbonate, and in its lower portion many
small Zerebratule and Inocerami. About ten feet of greenish-white chalk, somewhat
hard, is the next bed, in which few fossils are to be noted except a Terebratula and a
bone or two of a Star-fish. In all these strata enumerated there is a marked absence of
Belemnites, but in the succeeding and last bed, one of a bright-red colour, and more than
thirty feet thick, they become exceedingly abundant. This red band is the one from which
most of the Red Chalk fossils from Speeton are derived ; it is exceedingly fossiliferous. In
its uppermost portion very large Zerebratule may be obtained, and generally many of an
ordinary size; at about twenty feet below its commencement, Belemnites, Pentacrini,

SPEETON CLAY. 9

and spines of a Cidaris occur, which appear to be distinct from the Cidaris spines, ninety-four
feet above, in the pink band. There are, moreover, no traces of Holaster subglobosus nor
Discoidea cylindrica in this bright-red bed; and Ammonites cannot be seen, though so
numerous in the Speeton Clay, upon which it rests. This red band gradually becomes
nodular, and of a bluish cast, and gradually merges into the Speeton Clay.

“ Tnland the Yorkshire beds put on a somewhat different appearance, for on the escarp-
ment of the Wolds, as at Great Givendale, the beds of Red Chalk abound in pebbles
and in Zerebratule biplicate, a feature that is absent at Speeton, though conspicuous at
Hunstanton, in Norfolk.

‘A careful inspection of the fossils derived from the Red Chalk series of Yorkshire and
Norfolk shows that the two extremities of the bed are very distinct in character, and have not
much in common, and that the southern stratum is a more littoral deposit than the northern.”

My friend John Leckenby, Esq., F.G.S., of Scarborough, having studied critically the
fossils of the Speeton Clay, has kindly supplied the following note on that formation, from
which it appears that until now the true relations of this deposit have not been clearly
understood.

“The Speeton Clay of Yorkshire, besides many minor subdivisions, presents two
important and well-marked sections; well-marked lithologically, still more so by their
fossils. The line of separation midway, or nearly so in the series, is also distinct and clear,
with no passage-beds indicating a transition from one set of conditions to another. Its
entire thickness cannot be less than 4.00 feet, but in consequence of the denudation of the
inclined edges of its beds it nowhere presents a continuous section of more than 150 feet.

“The lower division is characterized in its upper beds by Ammonites and Gas-
teropods, which I at one time felt inclined to refer to the Oxfordian system, and many
palzontologists yet contend that the thick coronated Ammonites which here abound
belong to the Oxfordian group. Without, however, doing violence to our preconceptions
of stratigraphical relations, we shall find that they approach much more nearly to
Portlandian types, as figured by d’Orbigny ; and Am. Gravesianus cannot be distinguished
from a common, but unpublished form, in the Speeton Clay. In the lowest beds of
this lower division are found Am. triplicatus, Am. excavatus (var. alternatus, Von Buch),
with univalve and bivalve shells identical with species which [ have obtained from the
Kimmeridge Clay of Lincolnshire, in a railway-cutting near Brigg. The line of demarcation
before referred to is characterized by a thickish band of pseudo-coprolites, and by many
remains of Saurian animals; it would appear that here there has been a period of repose,
during which the Saurian dwellers upon a shallow reef disported themselves, and that we
have a well-marked division between the close of the Jurassic and the commencement of
the Cretaceous period. A large and almost perfect example was lately procured and is now
in the possession of Right Hon. Lord Londesborongh, the lord of the manor of Speeton.

“The habit of referring the whole of the Speeton Clay of Yorkshire to the Cretaceous
period, in deference to established authorities, has hitherto prevented a clear reading of

2

10 UPPER GREENSAND.

the evidence furnished by its fossils, and from the fact of so many of its Ammonites of
the Oolitic type beg found, not zz situ, but in boulders, has led to the inference of the
existence, at some remote period, in Filey Bay, of great beds of Oxiord Clay similar in
character to the Oxford Clay of the south of England.

“The Ammonites can, however, with much more propriety, be referred to Portlandian
types, and the wasted beds which have furnished the boulders doubtless pertain to the
same epoch.

“ Above the line of Saurian remains alluded to, all the fossils belong to the Cre-
taceous type; and amongst the exact representations of a Neocomian fauna many others
are found which in general features closely resemble them. Amongst the former, Ammonites
Deshayesii, Leym., and Vermicularia Sowerbii may be mentioned, while Crioceras Beanit,
Phil., cannot easily be distinguished, if at all, from C. Cornuelianum, d’Orb.

“ If we seek for the equivalents of the Upper Greensand in the Speeton Clay, we must do
so rather in the lower beds of Red Chalk which overlie that deposit than in the clay itself ;
and the frequent presence therein of Znoceramus Coguandianus, d’Orb., favours this view.

“The junction of the lowest beds of Speeton Clay with the Coralline Oolite cannot
be traced along the coast, but may be seen at some distance inland, near the village
of Grimston, one of the stations on the line of railway between Malton and Driffield.”

The Gault is the equivalent of the tage Albien of d’Orbigny, and the Gault of the
‘Germans.

THE UPPER GREENSAND.

This formation forms an important feature in the physical geology of the Isle of
Wight; in Compton and Sandown Bays it is seen in its relative position to the Lower
Greensand below and the Chalk above, and in the Undercliff it forms a bold, mural,
light-coloured escarpment, with rugged lines of cherty beds, producing a fine effect above
the rich foliage which clothes the undercliff. According to H. W. Bristow,’ Esq., F.G.S.,
the Upper Greensand under St. Catherine’s Down is about 155 feet thick ; the lower fifty-
five feet consist of “bluish, sandy, micaceous beds, throwing out water at their junction
with the Gault, and passing upwards into yellowish-gray sand, also micaceous, with
sandstone and some chert, forty feet thick. Sandstone and chert imbedded in sand
make up the greater part of the rest of the section, the middle portion of which is
mostly blue chert based upon seven feet of sandstone, inclosing a bed of freestone four
feet thick, whilst the uppermost fifteen or twenty feet consist of calcareous sandstone,
forming a vertical face at the summit of the cliff.”

In the island the remains of Echinidz are not abundant in these beds ; the Upper Green-
sand, near Warminster and Devizes (Wilts) ; Blackdown (Devon) ; and near Charmouth
(Dorset), and Cambridge, are the best localities for the fossil Echinodermata of this formation.

1 “Memoirs of the Geological Survey,” the ‘Geology of the Isle of Wight,’ p. 24.

LOWER CHALK, AND CHALK-MARL. 11

CHLORITIC MARL.

At the base of the Chalk, and dividing that formation from the Upper Greensand, is
a remarkable fossiliferous bed, full of green specks of silicate of iron, and called, in
consequence, Chloritic Marl, which at St. Catherine’s Down measures five feet in thick-
ness. This Marl is characterized by a suite of fossils, some of which, as Scaphites equalis,
Sow., here appear for the first time, and seem to be special to the bed; with these are
found Ammonites varians, Sow., Amm. splendens, Sow.; several Protozoa belonging to
the genera Spongia, Siphonia, and Scyphia ; Ecutnoprrmata, as Ananchytes levis, Deluc ;
Catopygus carinatus, Goldf.; and Discoidea subuculus, Leske ; together with several species
of Morzusca. The same stratum occurs near Chardstock, from whence I have obtained
many fine specimens of Psewdodiadema tumidum, Forbes, P. subnudum, Ag., Pedinopsis,
Holectypus, and several other species, most of which are common to this rock and the
Upper Greensand, of which it probably forms the uppermost bed.

‘The Upper Greensand appears to correspond to the Glauconie crayeuse of the French,
the Zburtia of the Belgians, the Griimsand of the Germans, and the Blage Cénomanien of
d’Orbigny.

THE LOWER CHALK, AND CHALK-MARL.

The Chalk formation occupies a large area in the Isle of Wight, and in the southern
and eastern parts of England. It consists of nearly pure carbonate of lime, and in many
cases is almost entirely composed of microscopic shells, either fractured or entire. My friend
H.C. Sorby, Esq., F.G.S., by preparing thin slices of chalk on slides of glass for microscopic
examination, has shown that many beds of that rock consist of from 90 to 95 per cent.
of the cases of Foraminifera, and of comminuted shells. The chief difference between
the Upper or soft white Chalk, and the Lower or hard Chalk is caused by the filling up of
the cavities of the shells by calcite or crystalline carbonate of lime, where it has pro-
bably been deposited by infiltrating water, which has carried away some of the lime in
percolating through the higher beds. The Chalk formation is divided into Chalk-mazrl at
the base, Lower or hard Chalk without flints, and soft or Upper Chalk with flints. In the
Isle of Wight the whole formation is 1300 feet in thickness, whilst in England it varies
from 600 to 900 feet.

The Lower Chalk near Dover is of a grayish colour, and much indurated in parts. It
is very rich in Achinide, and contains several new species. Unfortunately, many of the
finest specimens are impregnated with iron, and perish by the decomposition of the
pyrites. At Lewes, in Sussex, it is a hard, close-grained rock, with an earthy fracture,
and contains many urchins in fine preservation.

The following section, by the Rev. W. D. Conybeare, of the Chalk cliffs near Dover,

12 WHITE CHALK.

exhibits so well the position and relation of the Gray Chalk, which contains so many
fine Echinide, that I have introduced it here for reference. ‘The strata lie in the following
descending order, and are collectively about 820 feet thick.

Ist. Zhe Chalk with numerous flints; it is about 350 feet thick, and may be thus
divided :
I. With few organic remains.

II. A bed consisting chiefly of organic remains in which numerous flints of
peculiar forms are interspersed ; and a few beds of flints run along it.

2nd. Zhe Chalk with few funts. This stratum is about 130 feet thick.
3rd. Zhe Chalk without flints is 140 feet thick, and consists of—

I. A stratum containing very numerous and thin beds of organic remains,
90 feet thick.

II. A stratum about 50 feet thick, with few organic remains.

Ath. The Gray Chalk. ‘his is estimated to be not less than 200 feet in thickness,
and is that from which has been collected most of the fine specimens of Cidaris
Bowerbankii, Forb.; Pseudodiadema ornatum, Forb.; P. tumidum, Forb.; P.
variolare, Brong.; P. Brongniarti, Ag.; P. Mackiei, Wowd., Salenia Austent,
Forb.; S. Clarkii, Forb.; S. gibba, Forb.; S. granulosa, Forb.; and S. peta-
lifera, Defr., with other specimens of Chalk-marl species.

The Lower Chalk and Chalk-marl are represented on the Continent by the Untere
Kreide and Pliner of the Germans, the Craie tuffeau of the French; and the Lage
Turonien of d’ Orbigny.

THE WHITE CHALK.

The uppermost portion of the Cretaceous formation extends across the island in an east
and west direction, from the Needles to Culver Cliff, and all its beds are fully exposed in
several magnificent coast-sections ; as these beds are nearly vertical or highly inclined
at Alum and Scratchells Bays on the east, and at Culver Cliffs on the west, the sub-
divisions of the whole Cretaceous formation, and the way the beds pass into each other,
may be most satisfactorily ascertained. The bands of flints are well displayed in Scratchells
Bay and Culver Cliffs, and there is a fine exposure of vertical Chalk strata in a pit on
Brading Down; in all these localities, and many others which it is unnecessary to
enumerate, the flints appear as parallel layers at certain intervals in the strata, presenting
a striking contrast from their blackness to the snowy aspect of the Chalk with which they

are interstratified.
“Tn consequence of the high angle at which the Chalk dips throughout the greater

WHITE CHALK. 13

part of its range from west to east, the surface occupied by it is very inconsiderable com-
pared with that of most of the other strata above and below it, but its horizontal extension
becomes greater in proportion as the inclination of the strata diminishes. For this reason,
from Alum Bay to Mottestone Down, and from Carisbrook to Culver Cliff, between which
intervals the Chalk is nearly vertical, it constitutes a mere ridge of high land, which is scarcely
a quarter of a mile broad in Aston Down; but between Mottestone Down and Carisbrook,
where the strata are less inclined, the width of the Chalk exceeds three miles.”

“The flints in the Chalk are for the most part irregular in shape, but they sometimes
constitute tabular layers coincident with the stratification, or else filling cracks and joints.
Those flints which occur parallel with the bedding are of a different age from those filling
the cracks and joints. ‘The former are derived from siliceous matter, frequently, and
perhaps in most instances, deposited contemporaneously with the calcareous sediment of
which the Chalk is composed, around sponges and other organized bodies, the forms and
internal structure of which are still preserved. ‘The latter, on the contrary, are of more
recent origin, having been carried by percolating water holding silica in solution into cracks
and joints formed by the Chalk during or after its solidification. The tabular bands
of flint filling cracks and joints are therefore, and as might be expected on the last suppo-
sition, unfossiliferous, instead of abounding in fossils, as is the case with the other system
of flints.” ‘In the upper part of the Chalk, where the beds are the most highly inclined,
the flints, which appear to be whole when viewed ¢w situ, are found, on closer examination,
to be nearly all broken so that when extracted from the quarry they fall to pieces.”
“Shattered flints may be observed in the large chalk-pits south of Newport, and on Arreton
Down ; also on Ashley Down, where the Chalk is rather hard (as is most frequently the case
where it is inclined at a high angle), dipping 65° in a direction slightly east of north.’”

The White Chalk contains many species of Echinide, of which the most common are
Lchinocorys vulgaris, Breyn.; Galerites albo-galerus, Lamck.; Micraster cor-anguinum,
Klein; Cidaris clavigera, Konig; Cidaris sceptrifera, Mant.; Cidaris subvesiculosa,
d’Orbigny, and several other forms, to be figured and described in the following pages.

The “ Upper White Chalk with flints ” of English authors corresponds to the Craie
blanche of the French, the Odere Kreide of the Germans, and the Btage Sénonien of
d’Orbigny.

Besides the localities already mentioned, it is well exposed and very fossiliferous at
Lewisham, Grays, Northfleet, Norwich, Brighton, Dover, and other places in the counties
Sussex and Kent, and at Flamborough Head, on the Yorkshire coast.

The following table exhibits at a glance the subdivisions of the Cretaceous formations,
with their lithological characters, chief localities, and foreign equivalents, so as to afford
an easy reference to the stratigraphical distribution of the species of Hchinide in each of
the beds.

1 Bristow, on the “ Geology of the Isle of Wight,” ‘Mem, of the Geol. Sury.,’ p. 28.
2 Bristow, ibid., p. 31.

THE CRETACEOUS GROUP.

14 CRETACEOUS GROUP.

A TABLE OF THE CRETACEOUS GROUP OF ENGLAND.

SUBDIVISIONS. LITHOLOGICAL CHARACTER. LOCALITIES. FOREIGN EQUIVALENTS.

Nearly pure carbonate of lime, ae

minute fragments of Shells and Elo uobt Widhks
Lewisham, Grays,
Northfleet, Nor-

beds of which t a-
| upper beds of which are in =) wh Bastion.

Foraminifera, forming a white or

Uprrr CuaLk | yellowish-white, soft Chalk ;

eereee

Craie blanche, French.

Obere Kreide, Germans.
Etage Sénonien, d’Orb.
lar layers of dark silex coincident

tified with 1 f flints, or tabu-
Sener LAY CAS EL) SES DE ReaD Dover, Flam-
with the stratification. cei

ae | Hard Chalk, without flints, sometimes
a

CHALK-MARL.

Dover, Folkestone, ‘ Untere Kreide,Germans.

aout ie Lewes (Sussex), | Planer, Germans.
passing into Chalk-marl or cil Swaffham, au Craie tuffeau, French.

Gre . i
ray Chalk wich. Etage Turonien, d’Orb.

: Down, Isle of
numerous fossils.

; Glauconie r
Wight. ree era

French.
Tourtia, Belgians.

: Chard, Chardstock,
{ Light-coloured marl, full of green
Warminster, D
Siliceous sand, or nearly calcareous ewes “e F | Griinsand, Germans.

Be k i St. Catherine’s
Cuioritic Marb | specks of silicate of iron, “

? Petersfield, Cam-
often contains nodules of chert and :

masses of limestone.

; i vizes,Chute Farm, | — :
sand, with green grains ; the rock ? | Etage Cénomanien,d’ Orb.
Upper GREENSAND .

bridge, Char-
mouth, Dorset.

Dark-blue tenacious clay, sometimes
marly, with some concretions.

Hunstanton Cliff, Etage Albien, d’Orb.
Norfolk; Filey
Bay, Yorkshire.

coloured by the peroxide of iron
and haying numerous small sili-
ceous grains and pebbles of quartz,

of Wight,
Folkestone, Char-
mouth.
Gault, Germans.
&c., strewed throughout the mass.

=~]
&
o
Q
ise]
>
ec
tal
5

A grayish-coloured clay, the upper Filey Bay, York-

shire.

SPEETON aay
[Upper re

portion containing Neocomian, the
lower portion Portlandian species

of fossil shells. ;
Terrain Néocomien supé-

rieur of Swiss and
Isle of White,| French.
green grains, dark-coloured clays | Folkestone, Etage Aptien, d’Orb.
and clayey sands; and in some} Hythe, Maid-
localities, bands of limestone known | stone.
as Kentish Rag. J

posed of ferruginous sands with

A thin bed of hard, red Chalk, deeply :

Lower GREENSAND

| A great arenacous formation, com-

ECHINODERMATA. 15

CLASSIFICATION OF THE ECHINODERMATA.

The name EcHinoprRMATA was given by Klein, in 1734,’ to the shells of Sea-
urchins called Echini. Bruguicre® subsequently gave the name Echinodermata to that
division of the animal kingdom which comprised the Star-fishes and the Sea-urchins.
Cuvier® included in his class EcnrnoprrMss, with Asferias and Echinus, the Holothuria,
animals destitute of the prickly skin of the more typical forms, and which had many
external affinities with some Mollusca; and subsequently, in his ‘Regne Animal,”* he
grouped in this class es Hehinodermes sans pieds, forming the order Sipunculida, which
connect the Radiata with the Annulose Articulata.

The Echinoderms are highly organized animals, for the most part covered with a
coriaceous integument. In several orders it is strengthened with numerous calcarcous
pieces, which together form a complicated skeleton. The external surface of the skin, in
many families, develops spines of various forms, which serve as instruments of defence
or locomotion to the creatures possessing them. By far the largest number of these
animals have a complicated system of vessels for circulating water through their bodies.
These aquiferous canals are intimately connected with the life and motion of the animal ;
by means of this vascular water-system most of the typical groups erect those remarkable
suckers which protrude in rows from different divisions of the body; in the Hchinoidca
they escape through holes in the poriferous zones, and in the Astercidea pass through
apertures between the small plates forming the middle of the rays; whilst in the Sipun-
culida these organs are altogether absent.

No class of the animal kingdom more clearly exhibits a gradation of structure than
the Hehinodermata ; for, whilst some remain rooted to the sea-bottom, and in this sessile con-
dition resemble the Po/ypifera, others, clothed in prickly armour, and exhibiting the true
rayed forms characteristic of the central groups, conduct, through a series of beautiful
gradations, to soft elongated organisms, whose outline mimics the <Ascidian Mollusca,
whilst others exhibit the long cylindrical body, annulose condition of the skin, and
reptatory habits of the Apodous Annelida.

With so fertile a field for investigation, it is not surprising that the minute anatomy
of the Echinodermata should have engaged the attention of some of the most distinguished
zoologists of our age, and have yielded fruits which the physiologist reckons as amongst
the most marvellous contributions to morphological science.

1 «Naturalis Dispositio Echinodermatum,’ Jacobi Theodori Klein, 1734.
2 «Tableau Encyclopédique des trois Régnes de la Nature,’ 1791.

3 «Tableau Hlémentaire de |’Histoire naturelle des Animaux,’ 1798.

4 *Régne Animal destribue d’aprés son Organisation,’ 1834,

16 ECHINODERMATA.

The class Echinodermata is divided into eight orders, which, in descending sequence,
may be thus arranged:
oO

1. SIPUNCULOIDEA. 5. OPHIUROIDEA.
2. HoLtornuroIpEa. 6. BLASTOIDEA.
3. ECHINOIDEA. 7. CYSTOIDEA.
4, ASTEROIDEA. 8. CRINOIDEA.

Order 1. SrpuncuLoipra—form the apodal Annulose Ecliimoderms; they have a
long cylindrical body, divided into rings by transverse folds of the integument; they have
neither tubular suckers nor calcareous parts developed in their body, nor is it divided
into a quinary arrangement of longitudinal lobes; some have horny hooklets like the
feet of many Annulosa, which they much resemble; their mouth is provided with a
retractile proboscis, and surrounded by small tentacula, differing both in structure and
arrangement to the homologous parts in the Holothuria. In them the type of Radiata
vanishes and that of Azulosa appears. They are unknown in a fossil state.

Type. Stipunculus edulis, Pallas.

Order 11. HoLtornurorpua.—Body in general elongated; skin in general soft and
leathery, in a few genera strengthened by calcareous or horny spines. Five avenues of
suckers divide the body into as many nearly equal segments; mouth surrounded by
plumose tentacula, the numbers of which are usually multiples of five; vent at the
opposite extremity of the body; digestive organs consist of a large intestine, which makes
several coils in passing through the body; respiration performed by internal ramified
tubes, like a miniature tree; locomotion effected by contractions and extensions of the
body, and by rows of tubular suckers, similar to those in the Star-fishes and Sea-urchins.
The softness of their naked integument prevents their preservation in the stratified rocks.

Type. Cucumaria frondosa, Gunner.

Order 111. Ecninorpra.—Body spheroidal, oval, or depressed, enclosed in a test,
composed of twenty columns of calcareous plates, with ten rows of holes for the passage of
retractile tubular suckers; the surface of the test is studded with tubercles, which have
jointed with them moveable spines, of various sizes and forms in the different families
and genera; at the summit of the test is the apical disc, composed of give genital plates,
perforated for the passage of the ovarial and seminal tubes, and five ocular plates for
lodging the five eyes. The mouth, situated always at the under surface, is in many
genera armed with five powerful, complicated jaws and teeth, and in others the peris-
tome is edentulous; the vent occupies various different positions, sometimes within the
apical disc and surrounded by its elementary parts, sometimes external to the disc, and
at the upper surface, side, or base, the relative position of the vent to the disc affording

ECHINODERMATA. 1

an important character for the subdivision of the order into two primary groups. The
intestine winds rounds the shell, attached by a mesentery, the surface of which, as well as
the membrane lining the shell, is covered with vibratile cilia.

Type. The common Sea-urchin, Echinus sphera, Miller.

The EcninoipEa are represented by one family in the Paleozoic rocks, and by
numerous families in the Mesozoic and Tertiary groups, several of which characterize
these great periods of geological time. They likewise abound in our present seas.

Order 1v. Asreroipra.—Body stelliform, depressed, with five or more lobes or
hollow arms, forming a continuation thereof, and containing prolongations of the viscera ;
the mouth is always inferior and central, and the intestine often terminates in a vent
opening at the upper surface; in some genera the vent is absent; rows of retractile
tubular suckers occupy the ambulacral areas in the centre of the under surface of the
rays. Skeleton complicated, composed of numerous solid calcareous pieces, variable as to
number, size, and disposition ; skin coriaceous, studded with calcareous spines of various
forms; a madreporiform plate on the upper surface, near the angle between two rays ;
eyes placed at the extremity of the rays; reptation performed by tubular suckers.

Type. The common Star-fish, Uraster rubens, Linn.

This order is represented in the Silurian rocks by several genera. The Oolitic, Cre-
taceous, and Tertiary rocks contain many extinct forms. ‘The existing species are very
abundant in all our present seas.

Order v. Oputurorpra.—Body discoidal, distinct, depressed, provided with long,
slender arms, in which theré is no excavation nor prolongation of the viscera; they
are special organs of locomotion, independent of the visceral cavity, and have spines,
and membranous tentacula developed from their sides; mouth always below and central,
serving at the same time as the vent. Skeleton complicated, composed of calcareous
pieces, of which the size and number varies in different genera. ‘Their long, slender rays
are supported internally on a framework of central vertebra-like pieces ; they form special
organs of locomotion, independent of the visceral cavity, and numerous plates and _ spines
are regularly disposed along their sides to assist in reptation.

Type. The common Sand-star, Ophiura texturata, Lamarck.

This order is represented by one genus in the Silurian, and several genera are
found in the Oolitic, Cretaceous, and Tertiary rocks, as. well as in our present seas.

Order vi. Buasrorppa.—Body in the form of an oval calyx, composed of solid,
calcareous plates, provided with five inter-ambulacra and five ambulacra, the latter united
superiorly, striated transversely, and having a deep furrow down the middle ; ten ovarial
holes, opening into five at the summit, with a central oral aperture, a short, slender
stem, and the body destitute of arms.

3

18 ECHINODERMATA.

Type. Pextremites inflatus, Sow. Carboniferous Limestone.

The genera are all extinct, and belong to the Paleozoic rocks. One species appertains
to the Upper Silurian, six to the Devonian, and twenty-four are special to the Car-
boniferous rocks. .

Order vir. Cystorpra.—Body more or less spherical, supported on a jointed stem ;
the bursiform calyx is formed of close-fitting polygonal plates, varying in number in the
different genera, and investing the surface like a coat of mail, except above, where there
are three openings, one for the mouth, one for the vent, and one with a valve for the
reproductive organs; the fourth aperture is below, and continuous with the canal in
the stem. Some have two or four arms, others are armless; certain forms possess arti-
culated tentacula and curious comb-like appendages, or pectinated rhombs, in connection
with the plates.

Type. Pseudocrinites quadrifasciatus, Pearce. Upper Silurian.

This order is extinct. All the genera are found in the Silurian and Devonian rocks.

Order virt. Crinompra.—Body fusiform, distinct, formed of a calyx composed of a
definite number of plates, provided with five solid arms, independent of the visceral
cavity, and adapted for prehension; mouth and vent distinct; no retractile suckers ;
ovaries at the base of the arms opening into special apertures. Skeleton complicated,
calcareous, composed of thick plates closely articulated together; their number
and arrangement are determinate in the different families, the multiples of five being
those which predominate; the central plate of the body is supported on a long,
jointed column, that was firmly rooted to the sea-bottom? The mouth is central, and
prominent; the vent is situated at its side; the arms are mostly ramose and multi-
articulate, and when extended formed a net-like instrument of considerable dimensions.
The mouth is always placed upwards, and retained so by the column being jointed to the
central plate of the calyx. The normal station of the Crrnorpna is the reverse of the
Astrrorpea and HcHinoipEa.

Type. Pentacrinus Caput-Meduse, Miller. From the seas of the Antilles.

Extinct families of Crinoids have lived in all seas from the Silurian upwards, and
only one or two representatives now exist.

From the above analysis of the class EcuinoprRMATA, it appears that, as the Sipuncu-
loidea and Holothuroidea are not found in a fossil state, and the Blastordea and Cystoidea
are special to the Paleozoic rocks, our field of investigation in this Monograph is limited
to the Ecutnoipra, AsterorpEa, OpnivrompEA, and CrinorpeEa, which we now propose
to consider seriatim, commencing with the EcninorpEa.

ECHINOIDEA. | 19

Order —EcHINOIDEA.

The body is spheroidal, oval, depressed or discoidal, and enclosed in a calcareous
test or shell, composed of ten columns of large plates, ‘Le inter-ambulacral areas, and ten
columns of small plates, ‘he améulacral areas, separated from each other by ten rows of
holes, the poriferous zones. ‘The external surface of the plates is studded with tubercles
of various sizes, in the different families ; to these the spines are moveably articulated by
ball-and-socket joints; the spines are of various forms and dimensions, and serve well to
characterize the species.

At the summit of the test is the apical disc, composed of five genital plates, perforated
for the passage of the ovarial and seminal canals, and five ocular plates, notched or
perforated for lodging the eyes. There are two great openings in the test, one for the
mouth and the other for the vent ; the relative position of these apertures varies in different
_ families, and forms an important character in their systematic classification.

The mouth in some families is armed with a complicated apparatus of jaws and teeth,
in others it is edentulous. The internal organs of digestion consist of a pharynx,
cesophagus, stomach, and intestine, which winds round the interior of the test, attached
thereto by a delicate mesentery; its surface, as well as the ling membrane of the
shell, is covered with vibratile cilia; these cause currents of water to traverse the
interior of the body, and perform an important part in the function of respiration ;
the blood is circulated in arteries and veins, aided by a central pulsating organ or heart.
The five ovaries and testicles occupy the ambulacral divisions, and open externally through
holes in the genital plates. Locomotion is performed by the joint action of the
tubular retractile suckers and the spines. Many sea-urchins attach themselves to rocks
by their tubular feet, and some bury themselves in limestone and sandstone, or even
granitic rocks, by the abrading action of the spines.

The nervous system consists, according to M. Van Beneden, of a circular cord, which
surrounds the entrance to the digestive organs, and sends branches into the divisions of
the body. Professor Agassiz, and the late Professor Edward Forbes, regarded the organs
situated in the ocular plates as eyes, but M. Dujardin* denies them even a nervous
system. In the absence of more direct anatomical evidence on the point, the following
observation, related by M. Alcide d’Orbigny,” has an important bearing on the question,
and supports it affirmatively : .

Captain Ferdinand de Candé, who commanded the ‘ Cléopatre’ in the Chinese seas,
told M. d’Orbigny that he had captured, on the coast of that region, an urchin with long
spines, probably a Diadema, which he examined in a vessel of water, “I hastened to

1 Lamarck, ‘Animaux sans Vertébres,’ 2nd ed., tom. iii, p. 200.
2 «Paleontologie Francaise, Terrain Crétacé,’ tom. vi, p. 12.

20 ECHINOIDEA.

seize it,’ he observed, “when it instantly turned all its spines in the direction of my
hand, as if to defend itself.

“Surprised at this manceuvre, I made an attempt to seize it on the other side, when
immediately the spines were directed towards me.

“T thought from this that the urchin saw me, and that the motion of the spines was
intended as an act of self-defence; but, to prove whether the movement of the animal
was produced by my approach, or merely by the agitation of the water, I repeated the
experiment very slowly, and even over the water with a stick. ‘The urchin, whether in
the water or out of it, having always directed its defensive spines towards the object which
approached it. From these observations I arrived at the conclusion that these urchins
see, and that their spines serve them as defensive instruments.”

It is worthy of remark, that Captain Candé, at the time he watched this urchin, was
jgnorant of the anatomical fact that eyes had been detected in the Echinide, and his
inference was the conclusion drawn from carefully made observations.

The calcareous test of the Echinoidea is the only part of the structure of these animals
preserved in a fossil state. It has hitherto failed to attract that amount of atten-
tion from the paleontologist which the importance of its study demands ; although in a
stratigraphical point of view this skeleton is not inferior to that‘of any other class of the
Animal Kingdom. he fact seems to have been almost entirely overlooked by palzon-
tologists, that most of the generic characters of the different groups of Echinide are more
indelibly impressed on the separate pieces of their test than in the skeletons of any other
class of the Invertebrata.

Unlike the shells of the Mollusca, the test of the Echinoidea constitutes an internal and
integral portion of the animal, being secreted by, and enclosed within, organized mem-
branes, it participates in the life of the organism, and certain parts of the skeleton are
intimately connected with the organs of digestion, respiration, and generation, as well as
with those of vision and locomotion.

As it is intended to give an analysis of the test of the Echinoidea, with anatomical
details of the structure of the skeleton in the Echinodermata in general, in the General
Introduction to these Monographs, it is at present unnecessary to enter minutely into the
subject ; but, as many of our readers are doubtless unacquainted with the terminology
employed in the description of the test, and the characters on which a diagnosis of the
species is made, it is desirable now to preface our description with brief explanations of
the same, illustrating the terminology by a reference to the plates for accurate figures of
different parts of the test, and magnified details of the anatomical characters thereof.’

' In connection with the physiology of the Echinodermata, the following discovery, made by Dr.
Wallich, is most important :

“Thirteen living star-fishes, differing in no important particular from a species common on our own
and most northern coasts, were brought up from a depth of 1260 fathoms, or very nearly a mile and a
half, at a point midway between the southern extremity of Greenland and Rockall, and 250 miles distant
from the nearest land. ‘These star-fishes, however, cannot be said to have been captured by the sounding-

TERMINOLOGY. Q1

TERMINOLOGY,
Or a descriptive analysis of the component elements of the test of the Echinoidea.
The test of the Echinoidea is composed of the following parts :

a. Five ambulacral areas.
6. Five inter-ambulacral areas.

SS

Ten poriferous zones.

d. Vent-opening and anal plates.

e. Mouth-opening, peristome, buccal membrane and plates.

J. Five jaws when organs of mastication exist.

g. Tubercles of various sizes, developed from the outer surface of the plates.
i. Spines of different forms and dimensions, jointed with the tubercles.

These are the essential parts to be known ; others, of secondary importance, will be
described in their proper place in the Monograph.

The body of the Echinoidea is divisible into three parts :—1st. The calcareous envelope,
or skeleton, which has a globular, circular, oval, pentagonal, hemispherical, conoidal, or
discoidal form, and is composed of a framework of hexagonal, pentagonal, or polygonal
calcareous plates. This testaceous box is called the test; it is the form, the fes/, of
Agassiz; the general form, the test, of Desmoulins ; /e coguille, VOrbigny.

machine, for they came up adhering by their spine-covered arms to the last fifty fathoms of the sounding-
line, not as voluntary exiles from below, but owing to their having coiled themselves around a material
from which they found it impossible afterwards to disengage themselves. Now, apart from all other
evidence, the facts in connection with this particular sounding were sufficient to indicate that the star-
fishes had been raised from the sea-bed itself, and had not grasped the line whilst floating in some stratum
of water intermediate between it and the surface. But, by a singular piece of good fortune, the question
as to their last resting-place admitted of definite determination on evidence that they bore along with
them. To comprehend the value of this, it is necessary to mention that, by means of a separate observa-
tion taken upon the same spot, the bottom was found to consist almost entirely of the minute shell-covered
organisms (Foraminifera) already referred to ; and taking into consideration the fact that many of the shells
were completely filled with the gelatinous substance of whieh their bodies are composed, and, lastly, the fresh
appearance of this substance, the probability is very great that they, in common with the star-fishes, had
lived and multiplied at the bottom. But the only circumstance which ought to be accepted as direct proof
of their vitality, namely, motion after reaching the surface, was wanting; as it well might be, since
the passage through the vertical mile and a half of water occupied nearly an hour, and the change of
conditions to which the creatures became subjected during that period must necessarily have been very
great. Nevertheless, the chain of circumstantial evidence was rendered complete; for, on examining the
stomachs of the star-fishes, they were found to contain the minute shelled creatures in abundance, thus
clearly establishing the fact of the star-fishes having attached themselves to the sounding-line whilst it
rested on the bottom, and adding the strongest confirmation to the view that the minute creatures referred
to were brought up from their natural habitation.’ (Dr. Wallich, “On the Deep-Sea-Bed of the Atlantic, and
its Inhabitants ;”’ ‘ Quarterly Journal of Science,’ No. 1, p. 40.)

22 ECHINOIDEA:

2nd. The visceral cavity, containing the organs of digestion, respiration, circulation,
and generation, is formed entirely by the interior of the test.

3rd. The external surface of the test is covered with spines, which are moveably
articulated, with the tubercles seen on the surface.

The normal position of the body.—tIn describing the different parts of the test of the
Echinoidea, it is assumed that an urchin, the common purple heart-urchin, Spatangus
purpureus, Miller,’ for example, is placed before the observer. ‘The side with the single
ambulacrum lodged in the anteal sulcus, and the mouth in that third of the base, is the
anterior region. The side having the single inter-ambulacrum in the middle and the vent-
opening in the upper part of the border is the posterior region. The four other ambu-
lacra are disposed in pairs, and correspond to the right and left sides of the observer’s
body; there is, therefore, a right antero-lateral and a right postero-lateral, a left antero-
lateral and left postero-lateral, ambulacral area. The four other inter-ambulacra, besides
the single one in which the vent is situated, are likewise disposed in pairs, two of
these, with the single ambulacrum, forming the anterior part, the other pair, with the
pairs of ambulacra, the sides, and the single inter-ambulacrum the posterior part of
the test. |

All Echinoidez have the mouth situated at the under side of the body; the surface in
which the opening is placed is ¢he dase, that region of the test opposite the base is the
upper or dorsal surface.

The most convex part of the margin, border, or sides, between the base and upper
surface, is the cvrcumference, or ambitus of some authors ; it is round, flat, convex, angular,
or carinated, according to the general form and thickness of the test.

The length or antero-posterior diameter is the distance between the anterior and
posterior regions, and corresponds to the middle line of the body.

The dreadth or transverse diameter is the distance between the greatest lateral
convexity of the circumference in the direction of a line cutting the line of length at
right angles.

The eight is the distance between the most convex part of the upper surface and the
plane on which the base of the test rests. The apical disc is generally situated at the
vertex, but it is not always so; the height has always reference to the highest point of the
test, quite irrespective of any other consideration. The test has invariably two openings,
one for the mouth, the other for the vent.

The mouth-opening is always situated at the under surface; to its circumference is
attached the buccal membrane, and through the central aperture thereof protrudes the
five jaws (Pl. V, fig. 1; Pl. VII, fig. 1); when they exist, the buccal, like the anal mem-
brane in many families, is clothed with numerous small plates.

In the Cidaris, Rabdocidaris, Goniocidaris, Diplocidaris, and probably in all other

! The common Chalk-urchin Miraster cor-anginum, Klein, will answer equally well.

TERMINOLOGY. 23

Cidaride, the mouth-opening is central, circular, or slightly pentagonal (PI. IV, fig. 16) ;
but in Hemicidaris, Pseudodiadema, Hemipedina, Pedina, Echinus, and other Echinide, the
mouth-opening is more or less decagonal, its margin being divided by notches (enfai//es)
into ten lobes; the lobes, in general, are unequal in size, those corresponding to the
base of the ambulacra being the largest; they are called the amdulacral lobes; corre-
sponding to the base of the inter-ambulacra are the cxter-ambulacral lobes. The margin of
the mouth-opening is called the peristome, to it the buccal membrane which closes the
base of the test is attached.

The mouth-opening is central and armed with jaws in the Ciparip#, Ecuinipa,
SALENIDA, GALERITID#, and CiyPEaAsTERID&. It is more or less excentral and edentulous
in the Ecu1nonip&, Co~uyritipa, EcuinoLampip&, EcuinocorypDa, and Sparancipaz;
in them it is round, oval, or pentagonal; sometimes its margin is ring-like, or surrounded
by five prominent lobes; in others it is distinctly bilabiate.

The vent, or anal opening, is always in the upper surface, in the centre of the genital
and ocular plates, directly opposite to the mouth, and is either central or subcentral in
the Crparip&, Ecninipa, and Satentp# (PI. VI, fig. 1). In other families its position
varies much; sometimes it opens on the upper surface, as in some GaLeRitIpA and
Cassiputinm. Sometimes it opens on the margin or is swpra-marginal, marginal or
infra-marginal ; often it opens at the base between the mouth and the border. During the
life of the animal this opening is closed by an anal membrane and a series of small angular
anal plates ; their number and disposition varies in the different genera. The anal plates
are seldom preserved in fossil species, and the term anal opening is given to all that part
‘ of the test occupied by them and the vent. PI. VI, fig. 1 @, is a magnificent specimen of
Cidaris sceptrifera, Mant., belonging to the British Museum, in which the anal plates are
finely preserved zz situ.

The Ambulacral and Inter-ambulacral Areas.

The test is composed, Ist, of twenty columns of calcareous plates of different sizes, the
plaquettes, Ttifelchen, Assule of authors; they are pentagonal in form, and united by
harmonial sutures to form rays, which proceed from the mouth, where they have their
greatest breadth, to the apical disc, where they are narrowest. 2nd. Of a series of hexagonal
or polygonal plates, forming a disc, which occupies the upper surface of the test. 3rd. Of
ten rows of small plates, notched on their margins to form holes; these form the
poriferous zones. 4th. Of moveable spines, that are jointed with eminences on the outer
surface of the columnar plates.

The ambulacral plates form two narrow columns, which are bounded by two poriferous
zones. The space thus circumscribed is the amdwlacral area. There are five of these areas
in the test of the Echinoidea. In the Crmaritp# the ambulacral areas are very narrow,
and support only granules (Pl. VI, fig. 1, a, 6, c, d). In the Ecuinipa, they are much

24 ECHINOIDEA.

wider, and have large tubercles on their surface. ‘The comparative width of the ambulacra
as compared with the inter-ambulacra has led some authors’ to divide the family Cidaride,
including therein the Zchinide, into two tribes, the ANcustisrELL#, or Cidaride with
narrow ambulacra, and the LatisteLu#, or Cidaridee with broad ambulacra. These two
tribes nearly represent our two families ; the Crparipz are equal to the ANcusTisTELLA,
and the Ecuin1p# are nearly equal to the Latistr12.

One of the ambulacral areas is single, and always represents the anterior region in the
spheroidal Echinide and Salenide. ‘This is detected by its relation to the apical disc,
as the right antero-lateral plate always carries the madreporiform body; in the oval,
pentagonal, or elongated forms, its position and relation to the mouth renders it unmis-
takeable. ‘The four other ambulacra are disposed in pairs.

The ¢xter-ambulacral plates form two broad columns, composing the inter-ambulacral
areas ; of these, like the ambulacral, there are five, which alternate with them in the archi-
tecture of the test. The poriferous zones form the line of demarcation between these two
classes of columnar plates. The plates are all pentagonal, and many times larger than
the ambulacral; they carry on their surface the large primary tubercles. . Of the five inter-
ambulacral areas, one is single and posterior, and in all the Echinoidez which have the anal
opening external to the apical disc it is in the single inter-ambulacrum that the vent ter-
minates. ‘The other four inter-ambulacra are disposed in pairs, and form the greater
part of the anterior and lateral parts of the test ; they are the azferior pairs and posterior
pairs, respectively, to distinguish them from the odd area, which is the szzgle inter-
ambulacrum.

Pl. VI, fig. 1, shows the form and structure of the inter-ambulacra in the Cidaride.

In the Cidaride the inter-ambulacral areas have only two rows of primary tubercles ;
but in many of the Hchinide there are four, six, eight, or ten rows of primary tubercles

in these areas.
The Poriferous Zones.

The poriferous zones are situated on each side of the ambulacral areas (PI. VI, fig. 1) ;
they are composed of a very great number of small pieces, articulated together in such a
manner as to form a series of holes. ‘The corresponding edges of the plates remaining
uncalcified, at certain definite intervals produce foramina, which are destined for the
passage of retractile tubular suckers. ‘The form and structure of the poriferous zones form
a good generic character. As there are two poriferous zones bordering each ambulacral
area, it follows that there are ten zones. Some authors give the collective name ambulacra
to the zones and the area; but for obvious reasons, I consider tliem distinct sections of
the test, and treat them as such.

? Albin Gras, ‘ Description des Oursins Fossiles du département de I'Isére,’ p. 20. E. Désor, ‘ Synopsis

des Echinides Fossiles, p. 26.

TERMINOLOGY.

rhe)
ot

The pores are round, oblong, or elongated; the pores forming a pair may be equal or
unequal ; in relation to each other, they may be ¢ransverse or oblique, contiguous or
remote, and when united by a transverse sulcus they are said to be conjugate.

The pores are differently arranged in the zones in the different families: when they are
disposed in single pairs, they are said to be wnigeminal (Pl. VI, fig. 1, d); when in double
pairs, digeminal ; when in triple oblique pairs, trigeminal ; and when grouped in a greater
number, as in many living species of the genus Echinus, they are polygeminal.

When the zones extend in a straight uninterrupted line from the mouth to the apical
disc, they are said to be simple, as in the Cidaride, Hchinide, Salenide, Galeritide,
Echinonde ; when the zones, after parting from the apical disc, expand, and again
contract, thereby forming a leaf-like figure on the upper surface of the test, they are said
to be petaloidal, as in the Clypeasteride ; when the petal is not so complete, as in the
Cassidulida, it is subpetaloidal. The zones are complete when they extend without inter-
ruption from the mouth to the disc; they are interrupted when they terminate on the
upper surface, and reappear again at the base near the mouth; they are /mited when
they form only a star on the dorsal surface. These terms represent generic characters
of greater or less value, and require to be carefully noted in the description of the
species.

The Apical or Genital Disc.

The apical dise occupies the centre of the summit of the test, and is composed in
most genera of ten plates, namely, five genital plates and five ocular plates (PI. VI,
fig. 1, a). In the Salenide there is one or more additional plates introduced. Zhe five
genital or oviductal plates correspond to the summits of the inter-ambulacral areas ; two
plates form an antero-lateral pair, two a postero-lateral pair, and the single plate is
placed behind. On the right antero-lateral genital plate (Pl. VI, fig. 1, @) is a spongy,
prominent mass, called the madreporiform body; the plate supporting this body was
supposed by Agassiz and Desor always to represent the posterior part of the test, but I
have shown that it is invariably placed on the right antero-lateral plate. ’

The ocular plates are at the summit of the ambulacral areas; they are small, heart-
shaped bodies (PI. VIII, fig. 4, 4), wedged into the angles of the genital plates around
the circumference of the disc.

The suranal plates are found only in the Sarenip#; they consist of one or many
elements placed in the centre of the genital circle, and always before the anal
opening. .

The anal plates (P\. VIII, fig. 4, 4), are very small bodies, and variable as to number ; ~

they clothe the membrane of the anal opening, and are well seen in recent urchins; but
4,

26 ECHINOIDEA.

are seldom preserved in fossil species ; they are admirably shown, however, in the fine
specimen of Cidaris subvesiculosa (P\. VII, fig. 4), from the collection of our kind
friend, Dr. Bowerbank, F.R.S.

The Tubercles.

The plates composing the test of the Cidaride, Echinide, and Salenide, have
large tubercles developed on their surface; they are divided into primary tubercles, semi-
tubercles, secondary tubercles, minute tubercles, granules, and miliary granulation, In the
other families the tubercles are smaller, more numerous, and less complicated.

The primary tubercles form two rows in the inter-ambulacral areas of the Cidaride,
(Pl. I and II), and four, six, eight, ten, or twelve rows in many Lchinide.

The semi-tubercles are found at the base of the ambulacral areas of the genus Hemi-
cidaris. na section of the genus Hemipedina they likewise are found at the base of the
ambulacra.

The secondary tubercles are found in many of the Hehinide, ranged, in general, on the
ambulacral side of the primary tubercles. ‘They are found likewise on the centro-sutural
side of the primary rows of many Pseudodiadema, Pedina, Hemipedina, and Echinus.

The minute tubercles are the small tubercles found on the margins of the ambulacral
areas of the genus Crdarvzs (PI). VIII, fig. 1) ; and they sometimes fill up spaces at the base
of the inter-ambulacral areas. In some Pseudodiademata they are raised on little
eminences, and perforated like the secondary and primary tubercles. In this respect
they are distinguished from the granules.

The granules are small, round, hemispherical elevations, scattered more or less regularly
over different parts of the plates of the test. Im some species of the genus Cidaris they
are arranged in rows in the centre of the ambulacral areas, or form circles around the
circumference of the areolas of the primary tubercles (Pl. VIII).

The miliary granulation is formed by a number of small granules closely set together
in the centre of the ambulacra, or on the inter-tubercular surface of the large plates
composing the inter-ambulacra (Pl. VIII, fig. 1).

The primary tubercles of the genera Cidaris, Hemicidaris, Pseudodiadema,
Hemipedina, Pedina, &c., consist of the following parts :

The hemispherical tubercle, or mamelon, is sometimes perforated in the centre, some-
times imperforate, as in many ehinide (Pl. VU, fig. 3 c).

The oss, or mammillary eminence, is the conical prominence on the surface of the
tubercular plate; its summit supports the tubercle, and the margin thereof is crenulated
in Hemicidaris and Pseudodiadema, and smooth in Hemipedina and Pedina.

These characters are important for generic distinctions.

TERMINOLOGY. : 27

The areola, or scrobicule (Pl. VI, fig. 1, d), is the round, oval, or elliptical, smooth,
excavated space which surrounds the base of the boss. This space is sometimes narrow,
and its margin elevated into a ridge, that completely encircles it, when the scrobicule
or areolar circle is said to be complete ; if the upper and under sides of the circle are
wanting, it is incomplete, and the areolas are then said to be confluent.

The row of granules encircling the areolas is called the areolar or scrobicular
circle.

The miliary zone is the space comprised between two ranges of primary tubercles,
it is in general covered with a close-set granulation; when destitute of miliary
granules, it is said to be naked; the ambulacral and inter-ambulacral miliary zones
occupy these different regions of the shell.

When the granules are microscopic, and closely clustered together within certain
narrow, circumscribed bands, or fascioles, intersecting the general tubercular surface, and
occupying fixed positions on the test, they are called fasciolar.

Fascioles are only found in two families, in one genus of the Hehinocoride, and in
almost all the genera of the Spatangide. ‘he form, width, structure, and position of these
bands must be carefully noted, as they afford important characters, both positive, and
negative, for the diagnosis of the genera.

When a fasciole surrounds the circumference of all the petaloidal portions of the am-
bulacral areas, it is peripetalous ; if it encircles the single ambulacrum alone, it is internal ;
when it extends along the flanks, it is /ateral ; if it passes in whole, or in part, along
the circumference, it is marginal ; and when it surrounds the base of the single inter-
ambulacrum, it is swbanal. Sometimes there is only ove, sometimes there are fwo or
three, of these fascioles in different genera.

Each family has a special arrangement of the tubercles, granules, and fascioles; a
detailed account of these will be found in the general outline of the structural characters
prefixed to the description of each natural group.

The sutural impressions are the lines along which the plates are united together ; some-
times they are mere lines; or the impressions amount to excavations out of the borders
of the plates, and give rise to cavities therein, as in the genus Zemnopleurus.

The angular or sutural pores are small impressions, situated in some genera at the
angles of the plates, upon the median line of the miliary zones,

The external Appendages of the Test.

The spines, or radioles, as they were called by Plott, Lang, and other old authors, are the
calcareous appendages that are moveably articulated to the tubercles of the test; they
present numerous modifications as to size, form, and sculpture, which are all intimately

28 ECHINOIDEA.

connected with specific characters ; some are short or elongated, flattened, cylindrical, fusi-
form, or subulate ; others are compressed, spatuliform, or triangular ; others, on the contrary,
are expanded, pyriform, or claviform. The surface of the spines is smooth or striated with
fine or coarse longitudinal lines ; some have verticillate processes at regular intervals, others
have asperities, prickles, or granules, disposed with more or less regularity over the surface.
The different parts of the spine have received the following names :

The articular cavity, or acetabulum, is the socket by which the spine articulates with the
tubercle ; its margin is smooth or crenulated, according as the summit of the boss is smooth
or crenulated (Pl. VI and VII); im all the genera with perforated tubercles there is
a corresponding pit in the socket of the spine, for the attachment of the round ligament
which passes from the tubercle to the spine.

The ead is that part of the spine containing the articulating cavity, and is united to
the stem near the neck (Pl. VII, fig. 4).

The milled ring surrounds the head ; it is a prominent ridge, more or less deeply
crenulated, around which the muscular fibres that move the spine are firmly attached.

The neck is the smooth space between the line of junction above the milled ring and
the ragose body of the spine (Pl. VII and VIII). In long, slender, tapering spines, it is
often finely striated with longitudinal lines, and cannot be distinguished from the body into
which it passes.

The stem or body of the spine is the part that exhibits the greatest variety of forms,
smooth and muricated varieties are figured in Pl. I, II, IV.

The organs of mastication forming “ the lantern of Aristotle” are rarely preserved in
fossil species ; they consist of five jaws, each carrying a long tooth (Pl. V and VII). As
these parts form a complicated mechanism, their analysis and description will be given at
length in the anatomical part of the introduction.

On the relative value of the external organs in the classification of the Echinoidea.

The mouth is always basal, central, subcentral, or excentral, but the excentricity is
invariably towards the anterior border. ‘This opening does not, therefore, afford a charac-
ter of primary importance, although, in connection with others, it is valuable in the definition
of families. The mouth is sometimes armed with jaws, but it is oftener edentulous.

The position of the anal opening affords a character of primary importance. In one great
section the vent opens within the centre of the apical disc, surrounded by the genital and
ocular plates. The relation, therefore, of the digestive organs to those of generation and
vision, is an important primary character for the zoologist. In another section the vent
opening is without the apical disc, and is more or less external to, and at a greater or less
distance from, the genital and ocular plates. The physiological importance of the external
relation of the organs of digestion, generation, and vision, to each other, imparts great

~

CLASSIFICATION. 99

value to the position of the anal opening; and hence it forms the basis of the subdivision
of this order into two sections, which are thus defined :

LEichinoidea endocychca.

A. Test circular, spheroidal, more or less depressed, rarely oblong ; mouth in the centre
of the base. Vent in the centre of the upper surface, directly opposite to the
mouth, surrounded by five perforated genital plates, and having external to them
five ocular plates. Mouth always armed with five powerful calcareous jaws, formed
of many elements, disposed in a vertical direction.

Echinoidea exocyelica.

£&. Test sometimes circular and hemispherical; oftener oblong, pentagonal, depressed,
clypeiform, or discoidal; mouth central or ex-central. Vent external to the circle
of genital and ocular plates, never opposite the mouth, and situated in different
positions in relation to that opening: four of the genital plates are generally
perforated. The mouth is sometimes armed with five jaws, oftener it is
edentulous. ‘lhe elements of the lantern are disposed in a more or less horizontal
direction.

The structure of the ambulacral areas, and poriferous zones, afford good characters
of secondary importance for grouping the genera into natural families, especially when
taken in connection with the position of the vent, which varies in its relation to that of
the mouth-opening in different families.

The form, number, and arrangement of the tubercles, and the spines that are jointed
with them; the miliary granulation ; the bands of microscopic granules forming the fas-
cioles, having permanent positions on the test; also the size and number of the
elements of the apical disc, and the position of the vent, afford collectively good characters
for defining the genera.

The minute details of the structure of the plates ; the form, size, and number of the
tubercles on each of them; the arrangement of the pores, their proximity or remoteness
from each other in the zones; the general outline of the test, which has only certain
limits of variation ; the form of the areolas; the presence, absence, size, and distribution,
of the granules forming the scrobicular circle; the completeness or incompleteness of the
same ; the length of the spines, their form and sculpture, are points affording good specific
characters, as they are persistent details that are developed on every considerable fragment
of the test and spines of the Echinoidee.

30 ECHINOIDEA.

Taking these general principles for my guidance, I subdivide the Echinoidea into
the following thirteen natural families :

Cidaride.
Echinoidea endocyclica. Hemicidaride.
Vent within the genital plates, Diademade.
always opposite the mouth. Echinidee.
Salenide.
Echinoconide.
Order—ECHINOIDEA. Collyritidee.
Echinoidea exocyclica. Echinonide.
Vent without the genital plates, Echinobrisside.
never opposite the mouth. Echinolampide.
Clypeasteride.

Echinocoride.
Spatangide.

Family \. Ciparip#.—Test thick, spheroidal; inter-ambulacral areas very wide;
primary tubercles large, perforated ; bosses crenulated or uncrenulated, spines large,
thick, mostly claviform ; ambulacral areas very narrow ; poriferous zones narrow, pores
unigeminal, rarely bigeminal; mouth-opening large, inferior, central, circular or penta-
gonal ; peristome destitute of notches, always armed with large, powerful jaws. Vent-
opening wide, superior, opposite the mouth, surrounded by five large genital plates
perforated for the ovarial canals, and five small ocular plates excavated for lodging the
eyes; buccal and anal membranes covered with scales.

Types. Cidaris clavigera, Konig (Pl. IV). Czdaris sceptrifera, Mantell (Pl. VI).

Family 2, Hemicrparipa£.—Test thick, spheroidal, or more or less depressed ; ambu-
lacral areas narrow or wide, with semi-tubercles at their base only, or extended “throughout
the area; inter-ambulacral areas with two rows of primary tubercles, rarely more than
eight in each row; tubercles of both areas perforated, and bosses deeply crenulated ;
poriferous zones narrow and undulated; pores unigeminal throughout, except near
the peristome, where they are bigeminal and trigeminal. Mouth-opening large ; peristome
decagonal, and divided more or less deeply by notches into ten lobes; jaws large and
powerful; apical disc small, opposite the mouth, composed of five genital and five
ocular plates. Spines long, thick, cylindrical, tapering, claviform, or stout, compressed,
or.angular; surface smooth, or covered with fine longitudinal lines, as far as known,
neither prickles nor asperities are developed thereon.

Types. LHemicidaris intermedia, Fleming. <Acrocidaris formosa, Agassiz.

Family 3. Diaprmap&.—Test thin, circular, or pentagonal, more or less depressed ;

CLASSIFICATION. 31

ambulacral areas wide, with two or four rows of primary tubercles ; inter-ambulacral areas
with two, four, six, or more rows of tubercles, nearly of the same size and structure as
those of the ambulacra; tubercles perforated or imperforated, crenulated or uncrenu-
lated, in different genera; apical disc small, opposite the mouth, composed of.
five genital and five ocular plates; poriferous zones narrow; pores unigeminal or
bigeminal. Mouth-opening large and decagonal; peristome divided into ten lobes by
deep notches; spines long, cylindrical, more or less slender, either tubular or solid ;
sometimes encircled by spiral verticillate processes, or their surface is sculptured with fine
longitudinal lines.

Types. <Astropyga radiata, Leske. Cyphosoma Kenigii, Mantell. Pseudodiadema
tumidum, Forb.

Family 4. YKournrpz.—tTest thin, spheroidal; inter-ambulacral areas, with small
primary tubercles, of various sizes, perforate or imperforate; bosses crenulate or un-
crenulate; ambnilacral areas wide, always supporting two or more rows of primary
tubercles ; poriferous zones narrow or wide, pores unigeminal, trigeminal, or polygeminal,
and disposed in ares; spines short, mostly subulate. Mouth-opening large, inferior,
always decagonal; peristome divided into lobes by notches more or less deep. Vent
small, superior, opposite the mouth, surrounded by five genital and five ocular plates ;
buccal membrane naked.

Types. Lchinus sphera, Miller. Codiopsis Doma, Desmarest.

Family 5. Saventp%.—Test thin, spheroidal; inter-ambulacral areas wide, with few
primary tubercles, either perforate or imperforate, crenulate or uncrenulate ; ambulacral
areas narrow, carrying secondary tubercles. Mouth-opening small or large, inferior,
decagonal ; peristome more or less notched. Vent superior, surrounded by the plates of
a large apical disc, composed of more than ten pieces, occupying a wide aperture in the
superior part of the test. Poriferous zones narrow, pores unigeminal, except near the
peristome, where they are trigeminal. Spines long, subulate, circular, or flattened.
Species all extinct; the genera distributed in the Oolitic, Cretaceous, and Tertiary
rocks,

Types. Salenia petalifera, Defrance. Acrosalenia hemicidaroides, Wright. Gonio-
phorus lunulatus, Agassiz. Hyposalenia Wrightit, Desor.

Family 6. Ecutnoconip#.—Test thin, circular, elongated or pentagonal, elevated or
depressed ; inter-ambulacral areas wide, ambulacral areas narrow; external surface of
the plates covered with numerous small, perforated, and crenulated tubercles; pori-
ferous zones narrow, pores unigeminal, except near the base, where they are trigeminal.
Mouth-opening inferior, central, circular, or pentagonal, armed with five jaws; peristome

39 ECHINOIDEA.

notched, dividing the circumference into ten nearly equal lobes. Apical disc central,
superior, composed of five genital and five ocular plates; madreporiform body large,
extending from the right antero-lateral genital plate into the centre of the disc. Vent
situated at the upper surface, in the margin, or at the inferior surface of the test. Spines
small, short, subulate. Species all extinct; genera distributed in the Oolitic and
Cretaceous rocks.

Types. Lchinoconus albo-galerus, Klein. Pygaster semisulcatus, Phillips. Discoidea
cylindrica, Lamarck.

Family 7. Coxttyritip£.—Test thin, circular, or oval; ambulacral areas meeting at
two poimts, more or less apart, on the upper surface ; poriferous zones narrow, pores
unigeminal ; tubercles small, numerous, perforated, and crenulated. Mouth-opening ex-
central, small, round, oval; peristome feebly fissured; jaws unknown. Vent round,
oval, supra-marginal ; elements of the apical disc detached ;. four genital holes. Species.
all extinct, and distributed in the Oolitic and Cretaceous rocks.

Types. Collyrites ringens, Desmoulins. Collyrites ovalis, Parkinson.

Family 8. Ecuinoninm.—Test thin, oval; poriferous zones narrow, meeting at the
apical disc; pores unigeminal; tubercles of both areas nearly equal, neither perforated
nor crenulated ; spines stout, subulate. Mouth-opening nearly central, irregularly penta-
gonal, and edentulous. Vent oblong or pyriform, basal or marginal, closed by anal
plates ; apical disc nearly central; four genital pores. One group living in tropical seas ;
another fossil in the Cretaceous rocks.

Types. Lchinoneus cyclostomus, Leske. Pyrina Desmoulinsii, D’ Archiac.

Family 9. Ecutnosrtssip&.—Test thin, circular, oblong, sub-pentagonal or clypeiform,
covered with microscopic perforate tubercles, surrounded by excavated areolas ; ambulacra
narrow, enclosed by poriferous zones, more or less petaloidal ; pores set at different distances
apart, and united by connecting sutures. Mouth-opening small, nearly central, pentagonal,
edentulous, in general surrounded by five lobes. Vent, opening in a sulcus, in the
upper surface of the single inter-ambulacrum, or in a marginal depression thereof; apical
disc small, four genital plates; madreporiform body extending into the centre of the
disc. Species living and extinct, the latter distributed in the Oolitic, Cretaceous, and
Tertiary rocks, the former in the seas of New Holland, and the Antilles.

Types. Lchinobrissus clunicularis, Lihwyd. Clypeus Plotii, Leske. Catopygus carinatus,
Goldfuss. Pygaulus cylindricus, Desor.

Family 10. Ecutnotampipz.—Test thin, oblong, oval, elevated, or sub-discoidal ;
ambulacra large, petaloid ; poriferous zones wide; pores apart, and united by
suture ; zones extending near to the margin. Mouth small, surrounded by five lobes,

TERMINOLOGY. | 33

Vent transversely oblong, and infra-marginal; apical disc small, excentral, with four

genital holes. Some species are now living in warm seas, but the greatest number are

extinct, and distributed in the Oolitic, Cretaceous, and Tertiary rocks.
Types. Conoclypus Leskei, Goldfuss. Lchinolampas orientalis, Gray. Pygurus

Kenigi, Gray.

Family 11. Ciypnasrertp£.—Test thick, elevated or depressed, circular, elliptical, or
pentagonal; surface closely covered with small, nearly equal-sized tubercles, sunk in
the plates, and surrounded by ring-like areolas, tubercles carrying short hair-like spines.
Mouth large, central, and pentagonal, armed with five strong jaws, containing the
same number of teeth. Vent posterior, marginal or infra-marginal; interior of the
test divided by pillar-like processes, formed of the inner layer of the plates. The dorsal
portions of the ambulacral areas have a petaloid form, circumscribed by large poriferous
zones; the basal portions are narrow, rectilineal, or branched; the five genital
plates form a circle round the madreporiform body, and between these are wedged the
five ocular plates. This family includes the genera Clypeaster, Lamk., Laganum, Klein,
LEichinarachnius, Van Phels., Arachnoides, Klein, Scutella, Lamk., Dendraster, Agass.,
Lobophora, Agass., Encope, Agass., Echinodiscus, Breynius, Mellita, Klein, Runa, Agass.,
Moulinsia, Agass., Scutellina, Agass., Lichinocyamus, Van Phels., Lébularia, Lamk.,
Lenita, Desor.

Types. Clypeaster rosaceus, Lamarck. Scutella subrotunda, Lamarck. Lchinarach-

nius placenta, Gmelin.

Family \2. Ecurnocorip#.—Test thick, oval or cordate, and sometimes conoidal ;
ambulacral areas contracted ; poriferous zones narrow, pores unigeminal ; test covered with
small perforated and crenulated tubercles. Mouth small, excentral, tranversely oblong.
Vent nearly of the same size, oblong, marginal or supra-marginal. Apical disc elongated,
nearly central, with four genital pores; the cordate forms have an anterior central depres-
sion, and one genus has a marginal fasciole. he species are all extinct, and limited to
the Cretaceous rocks.

Types. Echinocorys vulgaris, Breynius.
granulosus, Goldfuss.

Hlolaster subglobosus, Leske. Cardiaster

Family 13. Spataneipa%.—Test thin, oval, oblong or cordiform, exhibiting the bila-
teral symmetry of the Echinoidea. Vent posterior and supra-marginal, closed by a com-
plicated series of small plates. Apices of the ambulacral areas united at the summit of
the test. The single ambulacrum has a different structure from the antero- and postero-
lateral pairs, and is lodged in general in a depression of the test, which extends to the

anterior border, and forms the anteal sulcus; test extremely thin, and covered with
Besides these there are some larger

small tubercles, which support hair-like spines.
5

34. ECHINOIDEA.

crenulated and perforated tubercles for supporting large spines. There are two or four
- genital pores, placed close together in some genera, but apart in others. The eye-
plates, five in number, are situated at the apices of the ambulacra, in a pentagonal form,
around the genital plates. On the surface of the test of some Spatangide certain delicate
lines are observed, having a smoother appearance than the tubercular surface of the test ;
these are the fascioles, which are strewed with microscopic tubercles, and destined to carry
very delicate spines. ‘The fascioles have a different disposition in each genus, and afford a
good character in making definitions of the same. When the fasciole surrounds the
ambulateral petals like an undulating groove, as in Hemiaster, Schizaster, &c., it 1s peri-
petalous ; when it surrounds the single ambulacrum, as in Amphidetus, it is internal ;
when it extends along the sides, as in Sedizaster, it is Jateral; when it surrounds the
circumference of the test, as in Pertcosmus, it is marginal ; when it is limited to the base
of the anal opening, it is swb-anal. Sometimes, in the same genus, more fascioles than one
exist ; thus the sub-anal and peri-petalous are frequently associated together.
Types. Spatangus purpureus, Miller. Brissus lyrifer, Forbes. Brissopsis Duciei,
Wright.

CIDARID A. 35

Family \—Crparipa.

Test thick, turban-shaped, more or less depressed at the oral and anal apertures.
Mouth-opening wide, central; peristome circular or pentagonal, without notches;
aperture closed by a buccal membrane, covered with small spines, metamorphosed into
imbricated scales, upon which the pores from the zones are prolonged.

Opening for the apical disc very large; disc composed of five large, equal-sized,
angular, genital plates, and five ocular plates ; vent opening in the centre, directly opposite
the mouth ; anal membrane clothed with small angular plates, unequal in size, and variable
in number.

Ambulacral areas extremely narrow, composed of a great number of very small plates,
having only minute tubercles, or rows of small granules on their surface, and never
supporting tubercles with primary spines.

Inter-ambulacral areas very wide, composed of large plates, rarely more than from six
to eight in a column; the external surface of each plate carries a large perforated
tubercle, raised on a prominent boss, and encircled by a round or oval areola, having
an elevated margin, on which are a circle of granules, usually larger than those filling the
miliary zone.

Poriferous zones narrow, extending without interruption from the margin of the buccal
membrane to the apical disc ; pores in general unigeminal, in one genus bigeminal ; pores
contiguous, or separated by septa more or less thick.

Jaws, five in number, forming a very powerful lantern, moveably connected with, and
supported by, a series of calcareous processes or auricles, arising from the inner surface
of the test; the teeth are more simple, and the lantern less complicated than in the
Echinide.

The spines in this family exhibit a great variety of forms, they are large, strong, cylin-
drical, fusiform, prismatic, club-shaped, or flattened; and their surface is covered with
fine longitudinal lines, or with prickles or granules, having in general a linear arrange-
ment, or a more or less irregular disposition; the form and sculpture of the spine has a
specific value, as its dominant characters appear to be persistent.*

The Cidarid@ are the most ancient type of the Echmoidea. The remains of different
forms of this family are found in the Paleozoic rocks, as well as in those of the Secondary

* The form and general character of the spine should, in every case, be examined with scrupulous
attention, and, whenever in fossil species the spines are found attached to their test, the facts connected
therewith should be noted with the greatest accuracy. ‘The neglect of this caution has been the cause of
much confusion, and led to some serious errors.

36 CIDARIS

and Tertiary epochs. In his valuable Synopsis, M. Desor describes six genera in this
family: these are Cidaris, Klein ; Rabdocidaris, Desor ; Diplocidaris, Desor ; Porocidaris,
Desor ; Goniocidaris, Desor; Paleocidaris, Desor. Of this number three are extinct—
Diplocidaris, Porocidaris, and Palgocidaris ; two contain both extinct and living forms
—Cidaris and Rabdocidaris ; and one is only found living—Goniocidaris.

A.—Species from the Gault.

Ciparis Gauitina, Forbes, MS. PI. I, fig. 2, a, 6, ¢, d,e; fig. 3, a, 6; fig. 4 a, 6, c.

C1pARIs GAULTINA, Forbes. Morris’s Catalogue of British Fossils, 2nd ed., p. 74,

1854.
— — Woodward. Memoirs of the Geological Survey, Decade vy, expl.,
pl. v, 1856.

The specimen figured in Pl. I, fig. 2, belongs to the British Museum, and was kindly
communicated by my friend, S. P. Woodward, Esq., F.G.S. It consists of five inter-
ambulacral plates, and a trace of an ambulacral area, with a number of spines. Detached plates
of this urchin resemble those of Czdaris vesiculosa, Goldf. In the large plate (fig. 2, 4),
magnified two and a half times, the depth is greater than the breadth; the wide circular
areola is nearer the lower border, its margin is elevated, and surrounded by a circle of thirteen
small tubercles, each set upon a distinct base ; the boss is flat, its summit smooth, and
the tubercle large and distinctly perforated ; the rest of the plate is covered with a fine
close-set granulation (fig. 2, a, 0).

The remaining fragment of the ambulacral area is too imperfect for description.

The spines vary in form; they are in general long and slender, and taper slightly
(figs. 2 and 3). The surface is covered with longitudinal ridges, the edges are distinctly
serrated (fig. 2, a, and fig. 3, 4), and the stem represents a miniature fluted column. ‘The
truncated summit shows a star-like structure (fig. 2, ¢), produced by the serrated ridges
meeting around the circumference of a central circle. ‘The neck is smooth, short, and
thick (fig. 2, d, and fig. 3, 4); the milled ring broad and flat, and covered with very fine
lines ; the head is short, and the acetabulum surrounded by a line (fig. 2, @).

In one of the broken spies that accompanies the plates the upper extremity is
expanded and cup-like (fig. 4, a, 4, c), whilst in the other spines the extremities are
contracted and truncated (fig. 2, a, c).

Afinities and differences.—This urchin very closely resembles Cidaris vesiculosa, Goldt.,
found in the Chalk-marl of Essen and Ruhr. The resemblance is so great between the
German and English forms, that without a comparison of specimens a correct diagnosis

FROM THE GAULT AND GREENSAND. 37

cannot be given. In Crdaris vesiculosa, Goldf., the marginal circle of areolar tubercles
is not so prominent as in Czdaris Gaultina, Forb., but the general character of the
ornamentation on the plates is the same in both. The spines figured by Goldfuss
closely resemble those of C. Gaultina ; they have the same slender, elongated form, and
fluted structure; most of them are spindle-shaped, and some have an expanded cup-like
termination, like the spine fig. 4, a.

Locality and Stratigraphical Position.—Cidaris Gaultina is a very rare urchin. I
only know the specimens contained in the Museum of the Royal School of Mines, and the
subject of our figures, which belongs to the British Museum; both these fossils were
obtained from the Gault at Folkstone. Cidaris vesiculosa, Goldf., on the contrary, has
been collected from the Chalk-marl of Germany, and the Grey Chalk at Dover.

B.—Species from the Upper Greensand.

CipaRis VELIFERA, Bronn. PI. II, fig. 2 a, 4, ¢, de, f; fig. 3 a, 6; fig. 4 a, 6.

CrpaRIs VELIFERA, Bronn. Jahrb., p. 154, the name only, 1835.

— PISIFERA, Agassiz. Catalogus Systematicus, p. 10, 1840.

— VELIFER, Bronn. Index Palzontologicus (‘‘ = Salenie@ sp.’’), 1848.

— Myrcuetint, Sorignet. Ours. Foss. de Eure, p. 18, 1850.

— GLOBICEPS, Quenstedt. Handbuch der Petrefactenkunde, p. 577, pl. 49,
fig. 17, 1852.

— VELIFERA, Woodward. Mem. Geol. Surv., Decade v, pl. v, 1856.

— Heperrt, Desor. Synopsis des Hchinides Fossiles, p. 12, 1858.

— VELIFERA, Desor. Ibid., p. 34, 1858.

— — Cotteau, Paléont. Francaise ; Echinides, pl. 1054, figs. 14—21,
p. 241. .

Test small, circular, depressed ; ambulacral areas narrow and sinuous, with four rows
of granules; inter-ambulacral areas wide, tubercles large and prominent, gradually
increasing in size from the peristome to the apical disc, where they are globose and con-
spicuous ; spines short, stems large and globular, surface covered with longitudinal rows
of pustular elevations.

Dimensions.—Height, three tenths of an inch; transverse diameter, eleven twentieths
of an inch.

Description —This beautiful little Cidaris is one of the oldest representatives of the
group possessing claviform spines, Radiol: glandarii, for all doubt about the identity of the

38 CIDARIS

test, and the spine appertaining thereto, is removed by the discovery of the interesting
specimen figured in Pl]. II, fig. 4, a. The spines of this species were first discovered in
the Craie chloritée of Essen and Frohnhausen, and were named by Bronn ve/ifer ; as the
asperities on their globular stem impart a peculiar character to them, and that author, in
his ‘Index Paleontologicus,’ referred them to a Salenia. M. Desor described a small
Cidaris Heberti from the Craie chloritée of Cap la Héve, which I believe to be the test of
this species. The short diagnosis given in the ‘Synopsis’ agrees so well with the speci-
mens before me that I have no hesitation in concluding it to be the same :-—‘‘ Petite espéce
a scrobicules petits et serrés, mais a tubercules trés-gros, surtout a la face supérieure.
Quatre rangées de granules ambulacraires.”

The ambulacral areas are slightly sinuous, and furnished with four rows of small
granules (fig. 2, e) closely set together, the marginal rows being the most uniform in their
arrangement. ‘The narrow poriferous zones lie in a deep groove formed by the prominence
of the adjoining granules ; the pairs of small holes are obliquely inclined, with thickened
septa, each having a small tubercle (fig. 2, ce) between them.

The inter-ambulacral areas have two rows of tubercles placed so near the poriferous
zones that the inter-tubercular space in the middle of the area is about the same width as
the ambulacra, whereby the ten rows of tubercles are situated nearly equidistant from each,
thus imparting a regular appearance to this species (fig. 2, ¢, 4). There are five tubercles
in each row, which increase gradually in size from the peristome to the disc ; the three
basal tubercles are small and set closely together (fig. 2, 4), whilst the two upper tubercles
are large and wide apart (fig. 2, c); the mammillary eminence is depressed, the areola are
narrow (fig. 2, e), and their margin surrounded by a circle of well-defined granules
(fig. 2,7). The tubercle is large and prominent, and the narrow boss on which it rests
is destitute of crenulations (fig. 2, e,/) ; the summits of all the tubercles are perforated, those
on the upper part of the test are, however, best preserved. A broad band of granula-
tions separates the two rows of tubercles; five or six rows of granules are closely placed
together ; and the granules in the band and those in the ambulacra are nearly of the same
size.

In the specimen figured at 4, a, there are seven spines attached to the test m their
natural order. The spines (fig. 3, a) have a very short neck and a large globular stem,
covered with rows of pointed elevations (fig. 3, 4) rising from the midst of an apparently
villous surface. The milled ring (fig. 4, 4) is close to the acetabulum, it is moderately
prominent, and crowded with fine lines. From the manner in which these globular spines
are arranged on this small test, very little mdividual motion was possible among them,
and yet the delicate surface of the spines, when examined with a lens, gives no evidence of
abrasion, from the friction of moveable bodies laid so closely together as these spines were
placed.

Affinities and differences.—The test of this beautiful little Cidaris is nearly related to

FROM THE GREY CHALK. 39

Cidaris clavigera, Konig, both in the form of the tubercles and the narrowness and depth
of the areolz ; but in the structure of the spines there is a manifest difference, which will
be more fully appreciated by comparing Pl. IV, fig. 1, exhibiting a series of spines of
C. clavigera, with Pl. I, fig. 3, 6, showing a magnified view of the spine of C. velifera.

Locality and Stratigraphical Position—W. Cunnington, Esq., F.G.S., of Devizes, to
whom I am indebted for the loan of specimens of this species, obtained them from the
Upper Greensand near Warminster ; I had seen the plates of the test and portions of the
spines, but never before have I seen these parts “ in situ.”

The foreign distribution of this urchin is as follows :—The spines are found in the
Craie chloritée of Essen, Prussia, and of Frohnhausen, Hesse-Cassel, and the test,
described under the name Cidaris Heberti, Des., was collected from the Craie de
Vendome, from the Craie chloritée du Cap la Heéve and la Madeleine, near Vernon
(Eure) in l’Etage Cénomanien, where ii is very rare.

C.—Species from the Grey Chalk.

Crparis Carteri, Forbes. Pl. I, fig. 1, a, 6, ¢, d,e, f.

Crparis Carrerti, Forbes. Memoirs of the Geol. Survey, Decade v, pl. v, 1854.
— — Morris. Morris’s Catalogue of Brit. Fossils, 2nd ed., p. 74, 1856.
_— — Desor. Synopsis des Echinides Fossiles, p. 12, 1858.

Test small, inflated, subconical; ambulacral areas narrow, winding, with two marginal
rows of moniliform granules, and a deep median sulcus; inter-ambulacral areas wide ;
tubercles small, remote; areolz at the equator narrow, complete, those on the upper plates
small, elongate, and obsolete.

Dimensions.—Height, eight lines ; transverse diameter, ten lines.

Description Should subsequent discovery confirm the opinion that this is an adult
test, it will be the smallest Cidaris in the English Chalk. It very much resembles, in
many points of structure, Cidaris sceptrifera, Mant., from which it differs, however, in
size and figure, and in the development of the tubercles and their areolz, especially those on
the upper plates. The ambulacral areas are narrow and winding ; they have two rows of
prominent moniliform granules on the extreme margins of the areas (fig. 1, c) ; and in the
depth of one equatorial inter-ambulacral plate I have counted sixteen of these; between
them is a deep sulcus, on which two indistinct central rows of microscopic granules are
sparsely distributed.

40 CIDARIS

The inter-ambulacral areas are wide, and consist of large, deep plates (fig. 1, c), about
four or five in each row, those at the equator are the largest; the tubercle is small
and perforated; the boss is flat, with a smooth summit; the areole are narrow and
complete, and encircled by a moniliform circle of sixteen small granules, raised on
scale-like plates (fig. 1, c) 3 from the equator to the mouth the tubercles and their
areola gradually diminish in diameter, and on the upper surface the plates they are very
deep, and their areole small, elongated, and entirely obsolete ; the inter-tubercular surface
of the plates is covered with close-set miliary granulations.

The poriferous zones are narrow and deeply sunk, in consequence of the thickness of
the plate-ornamentation ; the holes are small, the pairs oblique, and there are sixteen
pairs opposite one large inter-ambulacral plate, one pair of holes being opposite one of the
large marginal ambulacral granules.

The apical disc is wide, occupying all the summit of the test (fig. 1, a, nell
ovarial plates are large (fig. 1, 7), and of an irregular rhomboidal figure ;_ their eae is
covered with small granules sparsely distributed thereon, and the oviductal holes are
perforated at the outer third of the plates. The oculars are small and heart-shaped, and
interealated between the angles formed by the ovarials ; the orbits appear to have been
marginal.

Afinities and differences.—This species resembles Cidaris sceptrifera, Mant., but the
depth of the inter-ambulacral plates and the limited number in a column, together with
the smallness of the areole and the obsolete character of those on the upper plates, prove
that this urchin is quite distinct from that form.

Locality and Stratigraphical Position —The only specimen at present known was
collected by James Carter, Esq., F.G.S., of Cambridge, from the Grey Chalk of that
neighbourhood ; and it belongs to his collection. In Morris’s ‘ Catalogue’ it was stated by
mistake to have come from the White Chalk, and in M. Desor’s ‘ Synopsis,’ from the Grés
vert supérieure d’ Angleterre.

History.—This species was first figured in the ‘Memoirs of the Geological Survey,’
im plate v of the Fifth ‘Decade of British Organic Remains.’ ‘The original specimen
formed the subject of Mr. Bone’s drawings for this work.

FROM THE GREY CHALK. 4]

Ciparis vesicuLosa, Goldfuss. Plate II, fig. 5, a, 6, c, d; Plate III, fig. 1, a, 4, ¢, d, e.

CrpaRIs VEsIcuULosA, Goldfuss. Petref. Germaniz, t. i, p. 120, pl. xi, fig. 2, 1826.

—

— Agassiz. Prod. Mém. Soc. Nat. de Neuchatel, tom. i, p. 188, i836.
— Desmoulins. Titudes sur les Echinides, p. 332, No. 23, 1837.
= Bronn. etheea Geognostica, p. 607, pl. xxix, fig. 76, 1837.
_ Geinitz. Charakter der Schichten und Petrefacten Kreide-
gebirges, p. 89, pl. xxii, fig. 1, a, b,c, d, 1839.
— Roemer. Norddeutschen Kreidegebirges, p. 28, 1840.
— Dujardin, in Lamarck, Anim. sans Vert., 2e ed., t. iil, p. 338,
1840.
— Reuss. Versteinerungen der Bohm. Kreideform., p. 57, pl. xx,
fig. 14, 1845.
— Agassiz et Desor. Catal. rais. des Ech. Ann. des Sc. Nat.,
3e série, t, vi, p. 328, 1846.
_ Bronn. Index Paleont., p. 301, 1848.
— Quenstedt. Handbuch der Petrefacktenkunde, p. 575, pl. xlviii,
fig. 47, 1852.
SPINULOSA, Guéranger. Essai d’un rép. paléont. de la Sarthe, p. 40, 1853.
VEsIcULOSA, Desor. Synopsis des Echinides Fossiles, p. 11, pl. v, figs. 24,
25, 1855,
R@MeERI, Cotteau, in Davoust, Note sur les Fossiles spéciaux a la Sarthe,
p- 49, 1855.
VESICULOSA, Pictet. Traité de Paléont., 2nd ed., t. iv, p. 254, 1860.
— Cotteau et Triger. Hchinides de la Sarthe, p. 133, pl. xxv,
figs. 1—6, 1860.
— Cotteau. Note sur les Nchinides recueillis en Espagne, par MM.
Verneuil, Triger, et Collomb., Bull. de la Soc. Géol. de France,
2e série, t. xvii, p. 375, 1860
— Cotteau in D’Orbigny’s Paléontologie Francaise, t. ii, p. 222, pl.
1050, and pl. 1051, figs. 1—6.

Test circular, inflated, nearly equally depressed at both poles; ambulacral areas flexed,
depressed in the middle, and filled with from six to eight rows of close-set, nearly equal-
sized granules, diminishing to two or four rows near the disc and peristome ; poriferous zones
very narrow, and flexuous ; pores small, having a moniliform line of granules separating the
pores ; inter-ambulacra wide, four to five plates in each column; tubercles moderate in
size, perforated, and uncrenulated, set very wide apart on the upper half of the test;
areas round, superficial, much inflated at the border, and surmounted with a circle of
prominent, mammillated granules. Near the disc the tubercles on the alternate columns
become dwarfed, are destitute of areolee, and occupy the middle of a long granular plate ;
miliary zone large, much depressed, and filled with small equal-sized granules ; discal and
oral apertures about the same diameter.

6

A2 CIDARIS

Dimensions.—Height, nine tenths of an inch ; transverse diameter one inch and a half.

Description.—This urchin, which forms so characteristic a species in the Lower Chalk
of the Continent, as shown in the table of synonyms, has hitherto escaped the notice of
English geologists. ‘The species from our Upper Chalk, erroneously referred to this form,
being quite distinct from the true Cidaris vesiculosa, Goldf., from the Gray Chalk and
Upper Greensand ; specimens from each of these formations I have figured in Pls. IT and III.

The test is of moderate size, much inflated at the sides, and nearly equally depressed
at both poles; the ambulacral areas are flexuous, depressed in the middle, and filled
throughout with numerous rows of small, regular, close-set, equal-sized granules ; at the
equator there are eight rows, which, near their terminations, diminish to two or four rows
(Pl. III, fig. 1, d); the inner rows are those which gradually disappear, whilst the outer
rows are persistent throughout.

The poriferous zones are very narrow, piiiaen the flexures of the ambulacra ; they
are composed of small round pores, separated by a granule, the series forming a moniliform
line down the middle of the zone, fig. 2, d.

The inter-ambulacral areas are composed of very large plates, those in the upper half
of the columns being the largest and most inflated; there are from four to five plates in
each series. ‘lhe areas are circular and superficial, with very prominent borders sur-
rounded by a circle of distinct regular mammillated granules (PI. III, fig. 1, d) ; on the
under half of the test the tubercles are approximated (Pl. III, fig. 1, 4); whilst on the
upper half they are set wide apart, from the increased height of the plates (Pl. III, fig. 1,
a andc); near the summit the uppermost tubercles on the alternate columns are imperfectly
developed, and often destitute of areola, and placed in the middle of a long granular plate
(PI. III, fig. 1, a@and ec). The tubercles are moderate in size, and perforated ; the summits
of the bosses are quite smooth, and without any trace of crenulations (PI. III, fig. 1, e).

The miliary zone is large and much depressed, and provided with numerous flat,
uniform granules, closely set together on the entire surface of the plates (fig. 1, d).

The peristome is circular (fig. 1 4), and the opening for the apical disc (fig. 1, a) is
nearly the same diameter as the oval aperture.

‘he spines of this species, according to M. Cotteau, are elongated, cylindrical, sub-
fusiform, with compressed longitudinal ribs, more or less spinous, and denticulated, the
processes being always at regular distances apart. ‘Towards the base, the ribs diminish
and disappear, and the stem is provided only with fine, close-set striz. ‘The neck is short
and striated, the milled ring prominent, the articular head smooth, and surrounded by a
small groove.

Length, twenty-five to thirty millimeters ; thickness, five millimeters.

Variety, spinulosas, Agassiz : length, forty-seven millimeters ; thickness, six millimeters.

Affinities and differences.—This species is distinguished from Cidaris sceptrifera,

FROM THE GREY CHALK. 43

Mant., of the White Chalk, by having fewer tubercles in the columns, which are wider
apart in the upper portion of the test; the areolas are likewise shallower, and the border
more prominent. In Cidaris sceptrifera the tubercles are largely developed (PI. VI, VII),
with deep areolas surrounded by a circle of prominent granules, and with a narrow sinuous
miliary zone. ‘The spines likewise are large and fusiform, having their surface covered with
prominent spiny granules. Cidaris vesiculosa, Goldf., differs from C. subvesiculosa, V’Orbig.,
in having the test flatter, the tubercles smaller, less numerous, and more apart.

The specimens of this urchin, collected from the Upper Greensand of Wiltshire, were
by the late Professor Forbes* referred to Cidaris insignis, Gras. Through the kindness of
my friend W. Cunnington, Esq., F.G.S., I have been enabled to examine the beautiful
series of this species in his collection, and in PI. II, fig. 5, have figured his largest and
finest specimen. A careful study of these fossils has satisfied me that they are not the
species described by Dr. Albin Gras,’ and which he thus characterized :—*“ Aires ambula-
eraires ondulées, paraissant présenter deux rangées verticales de granules trés serrées et
rapprochées les unes des autres; probablement cinq tubercles inter-ambulacraires non
erénelés dans chaque rangée (quatre paraissent seulement dans notre exemplaire, dont la
partie supérieure manque). Sur les cing tubercles, les trois inférieurs augmentent pro-
gressivement de grandeur en allant de bas en haut; leurs scrobicules et leurs cercles scro-
biculaires ronds, saillants et formés de granules serrés, sont trés-prononcés, tangents entre
eux et avec ceux de la rangée voisine; ils sont au contraire presque effacée dans le petit
tubercle qui vient ensuite, lequel diminue brusquement et repose pourtant sur une trés-
large plaquette couverte de nombreux granules.” The ambulacral areas in C. vesiculosa,
Goldf., have, at the equator, six rows of small, equal-sized granules, closely arranged in
parallel lines, and diminishing to four rows at the narrowest parts. ‘This persistent
structure affords a character by which the species is distinguished from C. cnsegnis.

The British Museum contains a fine specimen of C. vesiculosa, Goldf., from the Gray Chalk
of Dover (PI. ILI, fig. 1). This test I have carefully compared with Mr. Cunnington’s
Upper Greensand specimens, and the examination has convinced me that they belong to
the same species; the test of the specimen from the Gray. Chalk is that of a larger, and
older individual; some of the plates, however, in the upper part of the columns, are
proportionally more inflated; but in all other respects its characters are identical with
those of the Upper Greensand forms.

The test is spheroidal, of medium size, and nearly equally depressed at both poles ; the
ambulacral areas form narrow, flexuous, granular bands, which decline towards the
central suture ; they are entirely filled with small, close-set, equal-sized granules, arranged
in regular parallel rows, of which there are from six to eight at the equator, diminishing
to four in the narrowest parts, near the peristome and apical disc; the poriferous zones

1 Morris, ‘Catalogue of British Fossils,’ 2nd ed., p. 74.
2 «Description des Oursins Fossiles du département de I’Isére,’ p. 21, 1848.

A4 CIDARIS

are very narrow, and the small pores are placed close together, each septum being sur-
mounted by a little granule; there are 23 pairs of holes opposite one of the large plates.

The inter-ambulacral areas are formed of Jarge deep plates, the limits of which are
very distinctly defined by well-marked sutural lines; there are four or five plates in each
column, those at the lower part of the test are small and regular (fig. 1, 4), and those at the
upper part of the column are large, deep, and rather irregular in figure, from the extreme pro-
minence of the areolar margin (fig. 1, a,c); each plate, with the exception of the uppermost
in each alternate column, supports a large primary tubercle ; it is surrounded by a shallow
circular areola ; the boss is not prominent ; and the summit is smooth, without a trace of cre-
nulation ; the tubercle is large, sessile, and perforated (fig. 1, e) ; the margin of the areola is
very prominent, which, in the larger plates especially, produces an inflation of their surface,
and probably suggested the specific name vesiculosa (fig. 1, a). A complete circle of mammil-
lated granules, larger than those on other parts of the test, surrounds the margin of the areole,
and forms a prominent boundary thereto (fig. 1, d). The uppermost plate in each alternate
column, in most specimens, is either destitute of a tubercle, or represented only by a rudi-
mentary warty body, without areola, and situated in the midst of a long, narrow,
imperfectly developed plate, on all sides surrounded by granules.

The mouth is small and circular, and of the same diameter as the aperture for the
apical disc, which is likewise entirely circular.

Locality and Stratigraphical Position—The specimen figured in Plate III, fig. 1, be-
longing to the British Museum, was collected from the Gray Chalk, at Dover, and the one
figured in PI. II, fig. 5, belongs to my friend W. Cunnington, Esq., F.G.S., Devizes, and was
obtained from the Upper Greensand of Wilts. The specimen in my own collection is
from the Gray Chalk of Dover. I believe this urchin is very rare, as I have seen very
few specimens in the different collections of Cretaceous fossils. The Rev. 'T’. Wiltshire,
F.G.S., has communicated a fragment, collected from the Red Chalk of Hunstanton Chiff,
together with three-detached spines, of the same species. I am inclined to refer to this
species the specimen, figured in Pl. III, fig. 3, collected by C. B. Rose, Esq., F.G.S.,
from the Red Chalk, and kindly communicated for this work. The test is much defaced
by friction, but still many of the more remarkable characters of the urchin are well
preserved.

History.—This urchin was figured and described for the first time by Goldfuss, from
some isolated plates and spines collected from the creta margacea of Westphalia; that
author cites, as identical with Cidaris vesiculosa, a fragment from the White Chalk of
England figured by Parkinson, but which belongs to another species, probably Cid.
perornata, Korb. This error has led to much confusion, for we find Cid. vesiculosa, Goldf.,
cited in many English lists as having been obtained from the White Chalk of Kent, Sussex,
and Wilts; whereas the new form now figured and identified with Goldfuss’s species has

FROM THE GREY CHALK. 45

been collected only from the Gray Chalk of Dover and the Upper Greensand of Wilts.
Cidaris vesiculosa, Forbes, is avery different form from the true C. vesiculosa, Goldf. ; and I
must refer the reader to the article on that species for more ample details. This _ species
has been beautifully figured and well described by M. Cotteau, both in his Monograph on
the Echinide of Sarthe, and his continuation of D’Orbigny’s Echinides de Terrains
Crétacés, in the Paléontologie Frangaise, a work which has profited so much by M. Cot-
teau’s extensive knowledge of this subject. ‘This species has now been identified and
figured as British for the first time.

Ciparis BowrrBanktl, Forbes. PI. II, fig. 1, a—d.

>

Ciparis BowERBANKII, Forbes, in Dixon’s Geol. and Fossils of Sussex, pl. xxix, fig. 4
p. 330, 1850.
— — Forbes, in Morris’s Cat. of Brit. Foss., 2nd ed. p. 74.

&

Test spheroidal, depressed, ambulacral areas with four or six rows of nearly equal-
sized granules ; inter-ambulacral areas wide, five or six large spinigerous tubercles, with
small areole in each column; miliary zone wide, filled with small, close-set,
equal-sized granules. Spines very large, thick, and inversely conical, stems short, the
surface covered with irregular, longitudinal rows of granulated spines.

Dimensions.—Transverse diameter one inch; height unknown.

Description.—The body of this Cidaris, which is very nearly allied to C. clavigera, is
more compressed above and below than in that species.

The ambulacral areas are occupied by four or six small, nearly equal, granular
tubercles in each transverse row, and the poriferous zones are narrow and slightly
sinuous.

The inter-ambulacral areas are wide; the spinigerous tubercles, five or six in each
column, have small areole, without prominent margins; the miliary zone is flat, and
undepressed ; and the entire surface is thickly covered with minute nearly equal-sized
granules, of which a circle of larger ones surround the border of the areole.

The primary spines, seen 7 situ on the test (fig. 1, a), are thick, almond-
shaped, inversely conical bodies, with a short neck, into which the body suddenly
contracts (fig. 1, 4); the milled ring is broad and prominent (fig. 1, c), and the acetabulum
has a narrow rim close to the ring; the surface is minutely granulated with small spinous
points, arranged in regular longitudinal rows (fig. 1, 4); the spines which clothe the
granular tubercles are small, compressed, conical bodies, with a striated surface (fig. 1, ¢) ;
several of these are found zz stu on the plates of the test.

46 CIDARIS

Affinities and differences.—This species most nearly resembles C. clavigera, Konig ; it
is distinguished from that species, according to Professor Forbes, by having “ the ambulacral
segments slightly broader in proportion to the inter-ambulacrals, and instead of their
breadth being occupied by transverse series of about four granular tubercles, two of which
are very small and inconspicuous, there are four, or, centrally, even six, nearly equal
granular tubercles in each transverse row. ‘The large spinigerous tubercles of the ambu-
lacral plates are placed in areola, much smaller in proportion to the entire body than in
C. clavigera, and the tubercles themselves are also smaller. The spaces between the
rows of spinigerous tubercles are wider; they are thickly studded with nearly equal
granules.”

The spines of C. Bowerbankii resemble those of C. clavigera; but the club-shaped
head occupies the entire stem in the former, whereas in C. clavigera the club-shaped head

is carried on the long stem. Compare PI. II, fig. 1, with Pl. LV, fig. 1—3.

Locality and Stratigraphical Position.—This species has been found only in the Gray
Chalk of Dover. The fine specimen I*have figured is unique, and belongs to the

cabinet of our kind friend Dr. Bowerbank, F.R.S.

Mstory.—First figured by Prof. Forbes, in Dixon’s ‘ Geology and Fossils of Sussex,’
who likewise established the species in that work. The same specimen has been kindly
lent by Dr. Bowerbank to figure in this Monograph.

CipaRis DissimiLis, Forbes. Pl. III, III a, figs. 1 and 2.

CIDARIS SCEPTRIFERA, Forbes, in Dixon’s Geology of Sussex, pl. xxv, fig. 3.
— DIssIMILis, Forbes, in Morris’s Cat. of Brit. Fossils, 2nd ed., p. 74.
— — Woodward. Mem. Geol. Survey, Decade v, expl. pl. v.

Test small, depressed, ambulacral areas narrow, flexuous, with six rows of small
granules ; inter-ambulacral plates, four to five in a column; areol circular, wide apart,
surrounded by distinct secondary tubercles ; principal tubercles prominent, bosses slightly
crenulated, the inferior oral tubercles minute, the uppermost discal, rudimentary, and
without areole ; miliary granules large and prominent; spines slightly fusiform, surface
covered with longitudinal lines of prickles.

Dimensions.—A. Transverse diameter eleven lines ; height six and a half lines.
B. Transverse diameter, one and one fifth inches.

Description.—This urchin resembles Cidaris sceptrifera in its general characters, but
was separated from that species by Professor Forbes in his MS. notes on this Cidaris.

FROM THE GREY CHALK. 47

The test is small and depressed at both poles; the ambulacral areas are narrow, with six
rows of granules at the equator, diminishing to two rows at the discal and oral apertures
@PIP TEE a; fig. 2, c):

The inter-ambulacral areas are wide, and the plates large, from four to five in a column ,
the areola are circular and wide apart, the margins prominent, and surrounded by
distinct secondary tubercles; the boss is prominent and slightly granulated ; the tubercle
is moderate in size and perforated; the tubercles near the peristome are small (fig. 2, 4),
and those nearest the apical disc rudimentary (fig. 2,@), and destitute of true areole
(fig. 2, c).

The miliary zone is wide and zig-zag, and covered with large prominent granules
(fig. 2 c), among which smaller granules are irregularly strewed.

I have given in fig. 1 a a drawing of the fine specimen of this species from the late
Mr. Taylor’s collection, now in the British Museum, and in fig. 2, a, 4, a larger specimen
from the cabinet of the Rev. T. Wiltshire, F.G.S.

The spines, according to Mr. S. P. Woodward, are of two kinds, “the largest above
twenty-four lines in length, slightly swelling above the collar (two and a half lines in
diameter), and then tapering to a fine point; collar short, striated finely ; shaft granulated
in lines; spines of the lower surface very slender, three- to six-sided, serrated at the
angles ; spines of the areolar circles two lines in length, compressed and striated.”

Fig. 1, 4, is a spine of C. dissimilis belonging to the British Museum.

Fig. 2, d, e, f, are spines from the collection of the Rev. T. Wiltshire.

Affinities and Differences.—This urchin so closely resembles C. sceptrifera that it was
identified as such by Professor Forbes in Dixon’s Geology of Sussex; in his manuscript
notes on more perfect examples he had separated it under the name C. dissimilis. All
the best specimens known to me I have figured in Pl. III a.

Locality and Stratigraphical Position.—This species was collected by Messrs. Clarke,
Dixon, Taylor, and the Rev. T. Wiltshire, from the Gray Chalk at Dover; the finest of
these specimens I have now figured for the first time. Fig. 1, a, 6, belonged to the
late Mr. Taylor’s collection, and is now in the British Museum. Fig. 2, a, 4, /, and figs.
3 to 5, belong to the Rev. T’. Wiltshire’s cabinet.

LMistory.—This Cidaris was referred to C. sceptrifera by Professor Forbes in his
description of that species in Dixon’s Geology of Sussex. The subsequent discovery of
more perfect specimens induced him to separate it from that form under the name of
C. dissimilis in the MS. notes he left on the Cretaceous urchins.

48 CIDARIS

D.—Species from the White Chalk.
Civaris CLAVIGERA, Kénig. PI. IV, Pl. V, figs. 1—15.

De Luc. Mém. sur un Echinide singulier Mém. Acad.
Roy. des Sciences, t. ix, p. 467, pl. xii, 1763.
Andree, J. G. R. Briefe aus der Schweiz nach Han-
nover Geschr. in dem Jahr., 1763.
CIDARIS PAPILLATA, var. Leske. Klein, Nat. disp. Echinoderm, p. 134, pl. xlvi,
figs. 2 and 3.
— sPINIS CLAVICULATIS, Parkinson. Organic Remains, t. iii, pl. iv, figs. 1 and
21, 1811.
— CLAVIGERA, Kénig, in Mantell’s Geol. of Sussex, p. 194, pl. xvii,
figs. 11 and 14, 1822.
— — Konig. Icones Fossilium Sectiles, 1825.
— — Agassiz. Prod. Mém. Soc. des Sc. Nat. de Neuchatel,
t. i, p. 188, 1836.
= — Desmoulins. Etudes sur les Echinides, p. 383, No. 34,

1837.
— PROFINQUA (pars) Desmoulins. Ibid., p. 332, No. 22, 1837.
— CLAVIGERA, Geinitz. Charakter der Schict. und Petref. Kreide-

gebirges, p. 90, 1839.
— ath Agassiz, Catal. Syst. Foss., p. 10, 1840.
— — Hisinger, Letheea Suecica, pl. xxvi, figs. 5, 6, 1840.

_ — Roemer. Norddeutschen Kreidegebirges, p. 28, pl. vi,
fig. 7, 1840.

— = Morris. Cat. of Brit. Fossils., p. 49, 1843.

— — Agassiz et Desor. Cat. rais. des Ech. Ann. Se. Nat.,

3e série, t. vi, fig. 327, 1846.

— — Reuss. Versteinerungen der Bohmischen Kreideform.,
p- 57, pl. xx, figs. 17—20, 1846.

= —_ Graves. Essai sur la top. Géog. du dép. de l’Oise,
p. 692, 1847.

— _ Bronn. Index Paleontologicus, p. 298, 1848.

_ — D’ Orbigny. Prodrome de Paléont., t. ii, p. 273, Et. 22,
No. 1246, 1850.
_— —_ Sorignet. Ours. de l’Eure, p. 1, 1850.

— — Forbes, in Dixon, Geol. of Sussex, p. 338, pl. xxv, figs.
10, 11; 14; 18,19, 20, 0852,

_ — Quenstedt. Handbuch der Petrefackt., p. 575, pl. xlviti,
fig. 46, 1852.

—_ == Forbes, in Morris’s Cat. of Brit. Fossils, 2nd ed., p. 74,
1855.

— — Desor. Synopsis des Echinides Fossiles, p. 12, pl. vi,
fig. 15, 1855.

— HeEBERTrI, Desor. Ibid., p. 12, 1855.

FROM THE WHITE CHALK. 49

CIDARIS CLAVIGERA, Pictet. Traité de Paléontol., 2nd ed., t. iv, p. 254,
pl. xeviii, fig. 8, 1857.
—_ — Cotteau. Paléontologie Frangaise; Ter. Crétacé, t. vii,
pl. 1069, 1070, 1071, p. 285, 1862.
= _ Dujardin et Hupé. Hist. Nat. des Zooph.; Echino-
dermes, p. 480, 1862.
— Hesenrt, Dujardin et Hupé. Ibid.

Test circular, moderately inflated, of medium size, and nearly equally depressed at
both poles. Ambulacral areas narrow, slightly flexed, with four rows of mammillated
granules, the inner being smaller than the outer rows; inter-ambulacral areas wide,
five very large tubercles in each row; areol# deep, circular, and complete; margin
surrounded by a circle of mammillated granules; tubercles large and imperforate, boss
smooth; miliary zone wide, not depressed, furnished with large granules; peristome
small, subpentagonal ; apical disc large, subcircular ; spines large, clavate, crowded with
longitudinal, prickly ribs.

Dimensions.—Transverse diameter, one inch and three tenths; height, seven tenths
of an inch.

Description.—The finest examples of this urchin extant are those’ now figured in
Plates IV and V, the one belonging to my friend, Dr. J. S.. Bowerbank, PI. IV, the
other to the British Museum, Pl. V, fig. 1; both these specimens were collected and
developed by the late Mr. Taylor, and formed part of his collection of Cretaceous Echino-
dermata. Having had abundant materials at my disposal for the illustration of this species,
I have endeavoured to give accurate figures of all parts of the test, as well as of the
remarkable spines which armed it. An examination of the series I have figured will
show how very much the spines, from different parts of the test, differ from each, and how
cautious we ought to be in founding species of Cidaris on the spines alone.

The test is of medium size, circular, moderately inflated, and nearly equally depressed
at both poles. The ambulacral areas are narrow, slightly flexed, and provided with four
rows of granules; the external are the largest, and most regular, and are elevated on
mammillated summits close to the border of the poriferous zones; the internal rows are
composed of smaller granules, irregular in size, arrangement, and extent; towards the
ends of the areas they diminish in size, and gradually disappear whilst the external
rows are persistent throughout. A number of microscopic granules are irregularly
scattered among the internal rows, and form a regular series at the angle of the external
granules, on the border of the poriferous zones, and opposite each pair of holes.

‘The poriferous zones are narrow, depressed, and slightly flexed ; the pores are large,
round, and open, closely approximated to each other, and having small elevated granules
on the septa (PI. IV, fig. 1, 4).

~

50 CIDARIS

The inter-ambulacral areas are wide (Pl. IV, fig. 1; Pl. V, fig. 2, a, 4), with five very
large, prominent tubercles m each row ; the areolas are narrow, deep, and circular, closely
approximated near the peristome (Pl. V, fig. 2, 4), and wide apart at the upper surface
(Pl. V, fig. 2, a); the margin is surrounded by a circle of small mammillated granules
(Pl. IV, fig. 1, 4, c), a little larger than those which fill the miliary zone; the boss is
small, and not prominent, and its summit quite smooth (Pl. IV, fig. 4, ec); the tubercle
is very large and prominent (PI. V, fig. 2; and Pl. IV, fig. 1, 4, ec); it forms three fourths
of a sphere, and the surface is imperforate; the tubercle nearest the disc is sometimes
surrounded by a rudimentary areola (Pl. IV, fig. 1, a; Pl. V, fig. 2, a), and placed
wide apart from its penultimate fellow. The areolas at the under surface are so closely
approximated that many of them are separated only by a single row of granules.

The apical disc (Pl. V, fig. 8) is wider in diameter than the peristome ; the five ocular
plates are large, with prominent orbits surrounded by a radiated structure; the ovarial
plates have a rhomboidal figure, with the hole distant from the border; the anal plates
are well preserved in the specimen fig. 8, in which sixteen plates remain in sztu; the
surface of all the elements of the disc is covered with small granules, set well apart from
each other ; fig. 3 shows the disc and its elements magnified two and a half times.

The jaws and teeth are iw sifu in the specimen belonging to the British Museum
(PI. V, fig. 1); the peristome is small (fig. 2, 4); and more than half the opening was
filled by a buccal membrane, on which two or three rows of scale-like plates are disposed
in an imbricated manner. PI. V, fig. 4, exhibits the buccal membrane and its plates
magnified two and a half times.

The form of the spines varies in different parts of the test. In general they are
claviform, more or less developed, with massive bodies, elongated necks, and small
articular heads. ‘I'he body and neck are ornamented with numerous longitudinal ridges ;
those on the massive body develope a denticulated, spiny margin, as seen in Pl. IV, fig. 5,
and in other series of spines figured in this plate. The denticulated ridges are sometimes
prominent and regular, unequal, oblique, and rudimentary ; on the neck the ridges are in
general smaller, longitudinal, and with finer denticulations on the margin ; at the inferior
third of the neck they diminish in size and disappear, and are replaced by granules, which
likewise fill up all the intermediate space between the ridges, both on the neck and
massive head. In some spines, with a large head and short neck, the weight of the
spine is diminished by a series of canals, which extend into the head beneath the spaces
between the ridges; the head is sometimes traversed by a large channel, opening at the
summit, as in a specimen (PI. V, fig. 6) from the Rev. 'I’. Wiltshire’s collection. ‘The
collar is very small, and finely striated; the milled ring is narrow, and separated from the
collar by a depression ; both ring and depression being finely milled ; the acetabulum (fig.
2) is mederately deep, with a well-defined ring round the margin. In Plate IV, I have
figured the finest specimen extant of this species ; it belongs to my friend Dr. Bowerbank,
and shews two tests with their spines attached zz sifu. ‘This specimen exhibits the various

FROM THE WHITE CHALK. 51

forms of the spines in different regions of the shell, and the series of figures between
3 and 23 shows some of the extreme shapes these appendages assume.

Affinities and Differences.—This urchin is readily distinguished from other species of the
White Chalk by its small test, equally depressed at both poles, narrow areola, prominent
imperforate tubercles, and large claviform spines, more or less elongated, and covered with
spinous ridges. In this respect it resembles C. Bowerbankii, Forb., Pl. I, fig. 1, from
which it is distinguished chiefly by the character of the spines, and the larger size of the
inter-ambulacral tubercles. Compare Pl. II, fig. 1, a, with Pl. IV, fig. 1.

Locality and Stratigraphical Position.—This is the most common Cidaris in our
White Chalk ; it is found at Woolwich, Gravesend, Lewes, Brighton, and in the same
formation in Wilts and Dorset. The specimens figured in Pls. IV and V were found
near Woolwich, and developed by the late Mr. Taylor. ‘The grand specimen figured in
Pl. IV is in the possession of Dr. Bowerbank, that in Pl. V, showing the dental apparatus,
peristomal plates, and apical disc, belongs to the British Museum. |

It is very abundant in the Btage Sénonien of France, and found, according to M.
Cotteau, at Dieppe, Fécamp, Tancarville (Seine-Inférieure) ; Falaise (Somme) ; Vernonnet,
Giverny, Clachaloze, Petit-Andelys, Pinterville prés Louviers, Hougue-marre, Sinneville
(Eure); Notre-Dame-du-Thil, Mory la Herelle, le Mesnil-Saint-Fermin, Pouilly La-
boissicre (Oise) ; Maintenon, Chateau-Gaillard (Seine-et-Oise) ; le Mesnil-Saint-Thomas
(la Poterie) (Eure-et-Loire).

THistory.—This urchin was first figured and described by De Luc in 1763, and after-
wards by Leske and Parkinson ; in 1822 by Mr. Keenig, in Mantell’s ‘ Geology of Sussex,’
who named it C. clavigera. he first accurate description of the test and spines was made
by M. Abbé Sorignet, who pointed out the size and imperforation of its tubercles as
important diagnostic characters. It has recently been well figured by M. Humbert for
M. Cotteau in the ‘ Paléontologie Francaise ;’ and Mr. Bone has given most ample details
from all the best English specimens that I am acquainted with.

Ciparis serrivera, Morbes, 1850. Pl. XI, fig. 1,a,4,¢gd¢f4 9, 4, fig, 6.

CipaRIS CLAVIGERA, Ievss. Versteinerungen der Bohmischen Kreidef., p. 57, pl.

xx, fig. 21, 1845.

— SERRIFERA, Forbes, in Dixon’s Geol. and Foss. of Sussex, p. 338, pl. xxiv,
figs. 15—19, and pl. xxv, fig, 2, 1850.

— puNcTILLUM, Sorignet. Oursins Foss. de Eure, p. 9, 1850.

— SERRIFERA, Fordes, in Morris’s Cat. of Brit. Foss., 2nd ed., p. 75, 1854.

— PUNCTILLUM, Desor. Synopsis des Echinides Foss., p. 15, 1856.

— — Dujardin et Hupé, Zoophytes ; Echinodermes, p. 481, 1862.

— sERRIFERA, Cotteau. Paléontologie Frangaise; Ter. Cret.; Echinides, tom.
ii, p. 293, pl. 1071, figs. 5—15, 1863.

52 CIDARIS

Test small, circular, convex above, flat below, poriferous zones narrow, depressed,
slightly flexed, pores oval, approximated, separated by a small granule; ambulacral areas
sinuous and depressed in the middle, with from six to eight rows of small, round granules ;
inter-ambulacral areas wide and inflated above, with four to five small perforated tubercles
in each row, placed wide apart, with a miliary zone between them; spines long, slender,
cylindrical, covered with longitudinal, compressed, spiny ribs, having a wide valley and
eranulated surface between them.

Dimensions.—Transverse diameter, one inch and one sixth; height, six tenths of
an inch,

Description—This beautiful urchin was distinguished by Professor Forbes from
C. clavigera, for which it had been mistaken by Reuss, and was first figured in Dixon’s
‘Geology of Sussex ;’ it forms a well-marked species, which is very rare in our Cretaceous
rocks. The test is small, and circular; inflated at the equator and upper surface, and
flattened below ; the poriferous zones are slightly flexed, narrow, and depressed ; the pores
are small, oval, and approximated ; there is a granule between them on the septum ; and
an oblong transverse ridge between each pair. ‘The ambulacral areas are narrow, and
slightly undulated ; the plates incline gently towards the median suture, and are provided
with from four to six rows of small, close-set granules, of which the external rows are the
largest, and raised on mammillated eminences; the smaller and shorter middle rows
disappear near the disc and the peristome, where there are only the two external rows
of mammillated granules ; there are from fifteen to seventeen files of granules opposite
one of the large plates. The wide inter-ambulacral areas are slightly inflated above and
near the equator, and have from four to five deep plates in each series; the areole are
small, and gradually increase in diameter from the peristome to the uppermost tubercle ;
on the uppermost plate of each alternate series the tubercle is nearly obsolete; the border
of the areola is a little elevated, and surrounded by a circle of small, spaced-out, mammil-
lated granules (fig. 1, d@), a little larger than those which fill the miliary zone; the boss
is small, the summit smooth, and the tubercle perforated in all the specimens I have
seen ; the inter-tubercular spaces and central miliary zone are filled with a fine, uniform,
close-set granulation; on the upper part of the shell the tubercles nearest the disc are
small, imperfectly developed, and surrounded by the merest trace of an areola; the
sutures of the plates are depressed and conspicuous ; the peristome (fig. 1, 4) is small,
circular or subpentagonal; the discal opening is larger than the peristome, and sub-
pentagonal ; a portion of the disc, concealed in the specimen (fig. 1, a), exhibits a finely
granulated surface.

In a fossil I collected twenty years ago at Lewes, in Sussex, many of the spines
are preserved 7m s¢u on the fragment of the test (fig. 1, e, fg); they are long, sleuder,
and cylindrical, having seven or eight compressed ridges, with a denticulated border; the

FROM THE WHITE CHALK. 53

valleys between the ridges are concave, and the surface of these is very finely granulated ;
the neck is long and smooth (fig. 1, 7 and fig. 2); it is bounded by a fine line, and
beyond this is a narrow circle with microscopic lines conducting to a milled ring, which is
prominent and finely sculptured (fig. 1, 7, and fig. 2); the head is small, and the rim of
the acetabulum striated; the small secondary spines are flat and conical (fig. 1, 2), and
have the surface ornamented with fine longitudinal lines.

Affinities and Differences.—This species is allied to Cidaris vesiculosa, Goldfuss, but
distinguished from that form by having the test more regularly convex, the plates of
the inter-ambulacra less inflated, and fewer tubercles in each series. The spines of the
two species are likewise different. It resembles Cidaris sceptrifera, Mantell, but has smaller
areolas, less prominent scrobicular circles, fewer tubercles in each column of plates ; and the
spines are very distinct (compare for example PI. VII, fig. 1, with Pl. XI, fig. 1). According
to Professor Forbes, it differs from Cidaris subvesiculosa, VOrbigny, m having the inter-
ambulacra composed of large plates with impressed areolz around the spiniferous
tubercles, four to six in the perpendicular row. ‘Tubercles larger in proportion to the
areole than in the last species. Superior plates with indistinct tubercles, but not so
obsolete as in C. subvesiculosa. Granulated portion of the plates finely grained; the
sutures are not impressed; the avenues of pores, of which about fourteen correspond to
the largest plate, are broader in proportion to the ambulacra. There is a tubercle
between each pore, and an oblong transverse ridge between each pair.

Locality and Stratigraphical Position —I1 collected, about twenty years ago, a
specimen of this urchin with the spines attached to the test, in the Upper Chalk, at Lewes,
in Sussex; the example of this species figured in Dixon’s work was obtained from the
same locality. The fine fossil which I have figured in Pl. XI, fig. 1, was kindly com-
municated for this Monograph by Henry Willett, Esq., F.G.S., Brighton. This specimen
appears to be the original fossil which was figured before by Sowerby in Dixon’s ‘ Geology
of Sussex ;’ if so, it formed the subject of Professor Forbes’ observations.

In France this urchin is very rare; it was found in the Etage Sénonien at Civieres,
Giverny (Eure); Royan (Charente-Inférieure).

History.—This species was first well figured as Cidaris serrifera by Professor Forbes
in Dixon’s ‘ Geology of Sussex’ in 1850. The same year M. Abbé Sorignet described
it under the name C. punctillum in his work on the Fossil Urchins of the Department of
the Eure; as this account was not accompanied by a figure, I have retained the name
of the figured specimen. In 1845, Prof. Reuss figured this Cidaris in his fine work on
the Fossils of the Bohemian Chalk-formation, and erroneously referred it to Cidaris

clavigera, Konig, from which it differs in many important details both in the structure
of the test and spines.

CIDARIS SCEPTRIFERA, Mantell. Pl.

Vil a, figs.

CIDARIS CUCUMERINA,
— SCEPTRIFERA,

— CRETOSA,

— VESICULOSA,

aS SCEPTRIFERA,

‘lest moderately large and inflated

CIDARIS

V, figs. 16,17; Pl. VI; Pl. VIL, figs. 1,2; PL.
1, 3.

Parkinson. Organic Remains, vol. iii, pl. iv, fig. 2, 1811.

Mantell. Geol. of Sussex, p. 194, pl. xvii, fig. 12 (spine),
1822.

Agassiz. Catal. Syst. Ectyp. Foss., p. 10, 1840.

Roemer. Norddeutschen Kreidegebirge, p. 28, 1840.

Morris, Catalogue of Brit. Foss., p. 49, 1843.

Agassiz et Desor. Catal. rais. des Hchinides; Ann. Se.
Nat., 3e sér., t. vi, p. 328, 1846.

Reuss, pars. Versteinerungen der Bohmischen Kreidefor-
mation, p. 57, pl. xx, fig. 15, 1846.

Graves. Essai sur la Topogr. Géol. du Dep. de I’Oise,
p- 688, 1847.

Bronn. Index Palzontologicus, p. 298, 1848.

d’Orbigny. Prod. de Pal. Strat., t. ii, p. 274, 1850

Sorignet. Ours. de l’Eure, p. 6, 1850.

Forbes, in Dixon, Geol. of Sussex, p. 338, pl. xxv, figs. 3—7,
1850,

Forbes, in Morris, Catal. of Brit. Foss., 2nd edit., p. 74, 1854.

Desor. Synopsis des Echinides Foss., p. 13, pl. v, fig. 28,
1855.

Woodward. Mem. of the Geol. Survey, Dec. v, expl. to
pl. v, fig. 12, 1856.

Leymerie et Raulin. Stat. Géol. du Départ. de l’Yonne,
pp- 510—620, 1858.

Coquand. Synops. des Foss. Form, Crét. du Sud-Ouest de
la France; Bull. Soc. Géol., 2e sér., t. xvi, p. 1013,
1860.

Cotteau et Triger. Ech. du Dép. de la Sarthe, p. 253,
pl. xi, figs. 1—8, 1860.

Cotteau. Paleont. Francaise, p. 251, pl. 1056-57 -58,
1863.

Hupé. Hist. Nat. Zooph.; Echinodermes, p. 480, 1862.

; more or less elevated, and nearly equally flattened

at both poles; ambulacral areas narrow, depressed, flexuous, with six rows of granules in
the middle, diminishing to four rows above and below; poriferous zones narrow, winding,
and depressed ; inter-ambulacral areas wide ; plates very large, five to six in a column;
areola deep, circular, with an elevated, prominent, scrobicular margin, encircled by a
series of small granules, scarcely larger than those of the miliary zone ; boss not prominent,
summit feebly crenulated in young, and smooth in old shells; tubercle moderate in size
and perforated ; proximal discal plate in each column with a rudimentary tubercle, and an
elongated obsolete areola; miliary zone filled with small, equal-sized granules, much

FROM THE WHITE CHALK. 55

depressed along the line of all the sutures; apical disc wide ; ovarial plates thick, large ;
ocular plates heart-shaped ; spines long, cylindrical, fusiform, enlarged at the inferior third,
and tapering gently to the summit; surface covered with regular, longitudinal rows of
spiny, projecting granules, the intervening space being finely shagreened.

Dimensions.—Height, one inch and four tenths; transverse diameter, one inch and
three tenths. )

Description.—A very good figure of a fragment of the test and spines of this urchin
was given in Parkinson’s ‘Organic Remains,” pl. iv, fig. 2, and a fair drawing of the
upper surface of the shell in pl. i, fig. 11; both were, unfortunately, unaccompanied by
any description.

This beautiful species attains a considerable size; the test is circular, and nearly
equally depressed at both poles (Pl. VI, fig. 1, c); the ambulacral areas are very narrow
and flexuous, with six rows of granules at the equator, diminishing to four rows at both
poles ; the external rows are the largest and most persistent, and the internal rows are
found only in the wide portion of the area; in large shells there are many smaller granules,
dispersed among the regular rows (PI. VI, fig. 1, d) ; the poriferous zones are very narrow
and depressed, following the flexures of the areas; the pores are small, round, closely
approximated, and disposed obliquely, having a minute granule on the septum, and there
are twenty-four to twenty-six pores opposite one of the larger plates (fig. 1, ¢).

The inter-ambulacra] areas are very wide, and there are from four to five large plates in a
column ; in consequence of the prominence of the scrobicular circle, each plate is thickened
at the middle, and the lines of sutures between the plates are all very much defined, in
consequence of the plate sloping away from the scrobicular circle to the suture ; the areolas
are wide and circular, and surrounded by a thick, prominent border (fig. 1, d), encircled by a
series of seventeen granules, each raised on a distinct, shield-like, mammillated plate; the
boss is not prominent, its summit is feebly crenulated in young shells, and smooth in old
ones (Pl. VI, fig. 1); the tubercle is moderately large and perforated; the plates near the
peristome (Pl. VI, fig. 1, 4) are disproportionately small compared with those of the
equator (fig. 1, c, d); and the last plate of each column in old shells (fig. 1, a, e, f) has
an elongated form, with a rudimentary tubercle, and curious elongated furrow, representing
an obsolete areola. Mr. Bone has given most accurate drawings of this remarkable plate
from the fine specimen in the British Museum; the singular star-like structure which
these plates form on the upper surface of the test, surrounding the large apical disc, forms
a remarkable character of this species, fig. 1, a.

‘The miliary zone is narrow, zig-zag, depressed in the middle, and provided with fine, close-
set, nearly equal-sized granules, very much smaller than those surrounding the areolas.

1 «Organic Remains,’ vol. iti, pl. iv, fig. 2.

56 CIDARIS

The apical disc is very wide (PI. VI, fig. 1, @); the ovarial plates are large, thick,
irregular pentagons (fig. 1, g), and the ocular plates are heart-shaped; the surface of
both series is covered with a close-set granulation; the ovarial and ocular holes are very
conspicuous in this species ; within the ovarials the external circle of anal plates are found
in situ (fig. 1, a, g, 4).

The mouth-opening (Pl. VI, fig. 1, 4) is nearly circular, and smaller than the anal
opening ; the jaws are strong and powerful, as seen in PI. VII, fig. 1, a, 6.

The spines are long, cylindrical, and fusiform, thickest at the lower third, and tapering
gently from thence to the point (Pl. VI, figs. 2—5); they are covered with small, spiny,
equal-sized granules, the points of which are directed outwards; they are arranged in
regular, longitudinal rows, with a valley between them ; the prickles diminish in size near
the collar, and at the summit of many of the large spines the rows of granules form a
stellate termination (Pl. VI, fig. 3, a, 4, e) ; the valleys are covered with a finely corrugated
surface, the eminences forming microscopic longitudinal lines. The neck is very short
and delicately striated (fig. 4, 4), the head moderately large, and the milled ring not
prominent; the rim of the acetabulum is feebly crenulated, and its concavity contains
a deep depression for the round articular ligament; the length of the large spines, figured
in Pl. VI, figs. 3 and 4, contained in the British Museum, is two inches and nine tenths.
One figured by M. Cotteau, from the French Chalk, is three inches long.

Affinities and Differences.—Cidaris sceptrifera so closely resembles, in many points of
structure, Cidaris subvesiculosa, d Orbigny, that by some they have been thought to be
varieties of one species ; the facts on which their distinctness may. be maintained are the
following: Cidaris subvesiculosa has a more elevated test, with a greater number of plates
in a column, the areolas are smaller and less depressed, the circle of scrobicular granules
is less prominent, and the obsolete tubercles on the upper plates of the columns are
smaller, more numerous, and differently formed ; the granules covering the miliary zone
are smaller, and more regularly disposed in rows radiating from the areola. The grand
distinction is found in the spines, which are much smaller in C. seepirifera, tapering, but
not fusiform, and covered with longitudinal serrated lines. Compare the different excellent
figures of Cidaris subvesiculosa, d’Orbigny, in Pl. VIII, with the admirable drawings of
Cidaris sceptrifera, Mantell, in Pl. VI and VII.

Locality and Stratigraphical Position—Cidaris sceptrifera is found in the Upper
White Chalk of Kent, Sussex, and Wilts. ‘The truly magnificent specimens figured in
Pl. VI, fig. 1, and Pl. VIIa, fig. 1, belong to the British Museum ; the specimens figured in
Pl. VI, fig. 2, and Pl. VU, fig. 1, belong to the Museum of the Royal School of Mines.
I need scarcely add they are the finest known.

In France, M. Cotteau enumerates the following localities in which this species is
found: Dieppe (Seine-Inférieure) ; la Faloise (Somme); Vernonnet, Giverny, Civieres,

FROM THE WHITE CHALK. 57

Petit-Andelys, Pinterville prés Louviers, Senneville, Evreux (Eure) ; Notre-Dame-du-Thil
Frocourt, les Blamonts, Therdonne, Pouilly, Reims, Broyes, la Herelle, le Mesnil-Saint-
Firmin, Mory (Oise) ; Chalons-sur-Marne (Marne) ; la Ferté-Loupiere (Yonne) ; Clachaloze,
Maintenon (Seie-et-Oise); Marcon (Sarthe); Villedieu, Limeray (Loir-et-Cher) ; le
Ménil-Saint-Thomas (la Poterie) (Hure-et-Loir) ; Aubeterre (Charente) ; Talmont, Saint-
Georges, Royan (Charente Inférieure). Btage Sénonien. Saint-Paterne (Sarthe) ; Etage

Turonien, zone Zerebratella Bourgeoisit.

Mistory—F¥irst figured by Parkinson in 1811; the test and spines are both well
drawn, so that no doubt as to the species intended can exist, although no description of
the urchin was given. In 1822, Mantell figured one of the spines, and gave it the
name which it still retais. This species was not indicated in France until 1840, when
it was entered in M. Agassiz’ Catalogus systematicus ; since then its test and spines have
been found in the localities enumerated above.

CrpaRis suByesicuLosa, @’ Orbigny. PI. VIII, figs. 2, 4, 5, 6.

CIDARES PAPILLATZ, Parkinson. Organic Remains, vol. iii, p. 39, pl. iv, fig. 3,
1811,
CIDARIS CRETOSA, Mantell. Geol. of Sussex, Trans. Geol. Soc., vol. iii, p. 205,
1835.
— PAPILLATA, Mantell, Geol. of Sussex, p. 194, pl. xvii, fig. 13, 1822,
— CRETOSA, Morris. Catal. of British Fossils, p. 50, 1843.
— VESICULOSA, Morris. Ibid., p. 51, 1843.
— PAPILLATA, Reuss. Die Versteinerungen der Bohmischen Kreideforma-
tion, p. 57, pl. xx, fig. 22, 1846.
— CRETOSA, Graves. Essai sur-la Topog. Geog. du Département de

lOise, p. 688, 1847.
= — Bronn. Index Palzeontologicus, p. 298, 1848.
— svuBvesicuLoss, d’Orbigny. Prod. de Paléontol. Strat., t. ii, p. 274, 1850.

— OoVATA, Sorignet. Ours. Foss. de l’ Eure, p. 9, 1850.

— AMBIGUA, Sorignet. Ibid., p. 10, 1850.

— VESICULOSA, Forbes, in Dixon’s Geol. of Sussex, p. 338, pl. xxv, figs.
1—4, 1850.

— — Quenstedt. Handbuch der Petrefactenkunde, p. 375, pl.
xlyiii, fig. 49, 1854.
— — Forbes, in Morris’s Catalogue of British Fossils, 2nd ed.,

p. 75, 1854.
— suByEsIcuLosA, Desor. Synopsis des Wchinides Foss., p. 13, pl. v, fig. 27,
1855. “Ny
— GRANULO-sTRIATA, Desor. Ibid., p. 14, pl. vy, fig. 26, 1855.
— OVATA, Desor. Ibid., p. t4.
— AMBIGUA, Desor. Ibid., p. 15.

58 CIDARIS

CIDARIS SUBVESICULOSA, Coquand, Bull. Soc. Géol. de France, 2e serie, tom. xvi, p.
1913, 1860.
— —_— : Cotteau et Triger. Tchin. du dép. de la Sarthe, p. 250, pl.
xli, figs. 1—9, 1860.
a — Cotteau. Paléontologie Francaise, Ter. Crétacé, tome vi, p.
257, Pls. 1059—1061, 1863.

Test large, circular, inflated, nearly equally depressed at both poles ; ambulacral areas
slightly flexed, wide, with six rows of nearly equal-sized granules at the equator,
diminishing to four and two rows at the poles, the external series being the largest and
most persistent; poriferous zones narrow, depressed, and composed of simple oval pores,
separated from each other by an elevation of the septum; inter-ambulacral areas wide, six
or seven large plates in a column; the three equatorial plates with large areolz, those
near the peristome small, and the two upper plates near the disc with small rudi-
mentary tubercles; areole circular, depressed, surrounded by a ring of mammallated
granules, boss flat, with a smooth summit, tubercle moderate and perforated ; miliary zone
wide, filled with fine close-set homogeneous granules, disposed in very regular horizontal
lines, radiating from the scrobicular circle to the border of the plates; peristome small
and pentagonal; apical disc large, ovarial plates wide, narrow, and perforated at a
distance from the border; ocular plates heart-shaped, with marginal orbits. Two con-
secutive series of cuboidal anal plates arranged within the pentagonal area formed by the
ovarials ; vent small and sub-central.

Spines slender, elongated, and cylindrical ; surface covered with longitudinal elevations,
having a fine serrated or spinous border gradually becoming attenuated towards the base ;
neck short, with longitudinal lines; milled ring prominent, articular surface without

crenulations.

Dimensions.—Specimen fig. 5—height, one inch and one tenth; transverse diameter,

one inch and seven tenths.

Description—This urchin has been mistaken for Czdaris vesiculosa, Goldf., from
which it differs, however, in many important characters ; these have already been indicated
in the description of that species (p. 41). ‘The test is in general of moderate size, and
nearly equally depressed at both poles; the ambulacral areas are slightly flexed, with six
rows of granules at the equator; the external rows have larger mammillated granules than
the inner rows, which gradually disappear as the area becomes narrower near the peristome
and disc; the poriferous zones are narrow, depressed, and sub-flexuous ; the pores are
oval, and oblique as they approach the disc, and the septa have small elevated granules
between the holes. The inter-ambulacral areas are large, the plates wide and deep, six or
seven in a column (PI. VIII, figs. 4, 5), the areolas are circular and moderately depressed ;
they are widely spaced out at the upper surface, and placed closer together at the infra-

FROM THE WHITE CHALK. 59

marginal region and near the peristome ; the margin is surrounded by a complete circle of
large mammillated granules raised on shield-like plates. On the two uppermost plates of
each column the areole are very narrow, or altogether obsolete (fig. 4, @). The boss has a
flat smooth summit (fig. 1, c), and the large tubercle is deeply perforated (fig. 1, ¢ and d).
The miliary zone is very wide at the equator, and becomes narrower near the peristome
and the disc. It is more or less depressed in the middle, along the line of the sutures,
and covered with fine homogeneous granules set closely together; the granules are
arranged in regular horizontal lines (fig. 1, c, d, e), which radiate from the circumference
of the areolz to the border of the plate.

The apical disc is large and pentagonal (fig. 4, a, 4), and well preserved ¢w si/w in the
fine specimen, fig. 4, a. The five large ovarial plates have an irregular rhomboidal form,
with the ductal holes near the border; the oculars are heart-shaped, and have marginal
orbits ; the anal plates form a double series within the discal circle, and the vent (fig. 4, 6)
is a small excentral aperture with a third series of small plates on its anterior part only.
All the elements of the disc are closely covered with the same style of granules that fill
the miliary zone.

The peristome, smaller than the discal opening, is of a pentagonal form; in none of
our specimens are the dental pyramids preserved.

The spines are long, slender, cylindrical, with longitudinal ribs having a spinous
border (fig. 2, a, 4); the valleys between the elevations have a finely chagreened surface ;
the neck is short and striated, the head moderately large, and the milled ring prominent
(fig. 2, c). The acetabulum has a smooth rim. One spine must have measured 23 inches
in length. The large mammillated granules surrounding the areola supported small, frat,
triangular spines (fig. 6), having their surface ornamented with longitudinal microscopic
lines, and articulated to the tubercle by a semicircular depression at the base. I have
figured one of these scrobicular spines at fig. 6, where the line shows the natural size, and
the figure is enlarged four diameters.

Affinities and differences.—TYhis species has long been considered to be the Cidaris
vesiculosa, Goldf., but is distinguished from that urchin in having the ambulacra less
flexed, a greater number of plates in the inter-ambulacral columns, the upper tubercles
of both series rudimentary, and in having the granules in the miliary zone arranged in
horizontal rows. Cidaris vesiculosa, Goldf., has a smaller test, the ambulacra much more
flexed, the plates in a column fewer, the tubercles consequently wider apart, the upper
tubercles largely developed, and the granules in the miliary zone not arranged in _hori-
zontal rows. ‘The spines in C. subvesicu/osa are long, slender, and tapering; those in C.
vesiculosa are shorter and thicker. This urchin so closely resembles C. perlata, Sorignet,
and C. Vendocinensis, Ag., that they appear to me to be only varieties of C. subvesiculosa,
d’Orbig. ; the spines of the latter likewise closely resemble those attributed to C. serrata,
Desor. It is possible that if a collection of good type-specimens of these different reputed

60 CIDARIS

species were compared with each other, they would be found to be only so many cognate
varieties of one form.

Locality and Stratigraphical position.—This species is found in the Upper Chalk of
Kent, Sussex, and Wilts.

In France M. Cotteau gives the following localities in which it is very common in the
Etages Turonien et Sénonien: Bolbec (Seine-Inférieure) ; Houguemarre,’Vernonnet, Petit-
Andelys (Eure); Notre-Dame-du-Thil, Tartigny (Oise); la Faloise (Somme); Saint-
Fraimbault, Margon, les Menus (Sarthe); Villedieu, Villiers (Loir-et-Cher) ; Semblancay,
Limeray (Indre-et-Loire); Briolay (Maine-et-Loire) ; Barbezieux, Aubeterre, Layalette,
Salles (Charente) ; Royan, Saint-Georges T'almont, Saintes, Cognac (Charente-Inférieure) ;
Perigueux, Trétissac, Neuvic (Dordogne) ; Bugarach, Soulatge (Aude).

History.—This urchin was first figured by Parkinson in 1811. The test and spines are
sufficiently well drawn, in the absence of a description, to enable us to identify the species.
In 1822 Mantell described, under the name C. crefosa, a Cidaris represented by Parkin-
son (‘Organic Remains,’ Vol. III, Pl. I, fig. 11), and united to fig. 3, Pl. 1V, of the
same work, which served as the type of C. subvesiculosa. Professor Forbes identified this
species with the C. vesiculosa, Goldf., and figured it under that name in Dixon’s ‘ Geology
of Sussex.” In 1850 M. d’Orbigny, in his ‘ Prodrome de Paléontologie,’ separated it from
that form under the name sudvesiculosa, which has been adopted by MM. Desor, Cotteau,
and other authors.

Crparts Mrrceyt, Cotteau. Pl. VIII, figs. 1, 2, 3.

Ciparis Mrrceyt, Cotteau. Paléont. Frangaise, Ter, Crétacé Echinodermes, tom. vii,
p. 281, pl. 1068, 1862.

Test large, circular, and elevated above, inflated and depressed below; ambulacra
narrow, depressed, and slightly flexed; two rows of small regular mammullated granules
on the external border, and four rows of smaller, irregular granules on the central portion
of the area; poriferous zones narrow, flexed, composed of round pores in oblique pairs ;
inter-ambulacra wide, six or seven large plates in a column; tubercles well developed at
the base and equator, but small and obsolete on the upper surface; areola circular,
depressed, margin surmounted by a circle of regular mammillated granules.

Dimensions.—Height, two inches ; transverse diameter, two and a half inches.

Description—This remarkable urchin, which appears to be an elevated variety of
Cidaris subvesiculosa, has been described by M. Cotteau as a distinct species under the

FROM THE WHITE CHALK. 61

name C. Merceyi. The test is large and circular, elevated at the upper surface, inflated at
the equator, and flat at the base (fig. 1, a, 6). The ambulacral areas are narrow and
slightly flexed, much depressed at the medium suture, and furnished at the widest part
with six rows of granules. The two marginal rows have larger granules, very regular in
size and arrangement, and raised on small plates (fig. 1, ¢); the four inner zones are
much smaller and less regular (fig. 1, ce); the poriferous zones are narrow, deeply sunk, and
slightly bent; the small round pores are disposed in oblique pairs, of which there are
twenty-one, opposite one large equatorial plate (fig. 1, ¢).

The inter-ambulacral areas are wide and largely developed; there are from six to
seven plates in each column, of which the four or five lower plates have large areolee, with
moderately sized tubercles ; the two uppermost plates are destitute of areole, and have
small rudimentary tubercles (fig. 1, a and 4). The areole at the base and equator are
narrow and deeply depressed, well spaced out from each other at the equator, and set
closer together at the base. ‘The scrobicular margin of one of the equatorial’ plates is
surrounded by’a circle of eighteen regular mammillated granules, larger than those filling
the miliary zone (fig. 1, ¢); the boss is prominent, the summit smooth, and the tubercle
moderately large and widely perforated (fig. 1, d). Above the equator the two or three
upper tubercles entirely change their character, the areola become extremely narrow or
disappear (fig. 1, 4), and the tubercle becomes a mere rudiment in the midst of the miliary
granulation. The plate of this series nearest the equator, the third from the discal end,
supports a very narrow areola (fig. 1, e) with a small tubercle, and on the two uppermost
plates the tubercles are mere warty rudiments surrounded by granules.

The inter-ambulacral plates are large, convex, and inflated (fig. 1, c, d, e) towards the
middle, and slope gently towards the sutures, which are very well marked in this species.

The miliary zoneis wide and well developed, depressed in the middle and between
the plates; the granules are fine, abundant, and homogeneous, and arranged in regular
lines that radiate horizontally from the areolse to the borders of the plate (fig. 1, ¢, d, e),
resembling in this respect C. subvesiculosa.

The mouth-opening is small, and the peristome iretiesgon oa! the upper surface of the
test is fractured, and the disc absent. M. Cotteau, who has figured a very complete
specimen of this Cidaris, says that the periproct is pentagonal and star-shaped, and the dise
solid and inflated, and Jarger than the peristome; the ovarial plates are thick and angular,
their internal surface smooth and marked by three facettes for articulation with the
external row of anal plates; the ocular plates are small, subpentagonal, deeper than wide,
and not notched at the summit of the ambulacra.

‘The spines have not been found in relation with the test.

Affinities and differences.—This species resembles in so many important particulars
the preceding species, that I hitherto considered it to be a conoidal variety of that form.
M. Cotteau says this is one of the most curious species of Cidaris. Its form is in

js

62 CIDARIS

general inflated and sub-conical, its superior inter-ambulacral plates are entirely deprived
of tubercles, the structure of its periproct and apical disc impart a peculiar physiognomy
to it, and clearly distinguish it from its congeners. It is distinguished from C. swé-
vesiculosa by its greater size, its inflated sub-conoidal form, its straighter ambulacra, and
smaller and less regular granules. Its inter-ambulacral plates are more numerous, and
the three uppermost plates in each column are entirely deprived of tubercles in the
specimen figured by M. Cotteau, and they are small and rudimentary in the urchin figured
in our Pl. VIII, fig. 2.

Locality and Stratigraphical position.—Collected from the White Chalk, where it is
very rare. ‘The fine specimen figured by Mr. Bone belongs to Dr. Bowerbank’s collection.
That figured by M. Humbert for M. Cotteau was collected at La Faloise prés Breteuil
(Somme); in the Etage Sénonien, where it is very rare. It belongs to M. Tombeck’s
collection.

CIDARIS PERORNATA, Forbes, 1850. Pl. VII a, fig. 2.

CIDARIS PERORNATA, Jordes, in Dixon’s Geol. of Sussex, p. 339, pl. xxv, fig. 8.
1850.
— LOoNGIsPprInosa, Sorignet. Ours. Foss. de l’Eure, p. 19, 1850.
— Sarrwacensis, d’Orbigny. Prod. de Pal. Strat., t. ii, p. 274, 1850.
— PeERoRNATA, Jordes, in Morris’s Catal. of Brit. Fossils, 2nd edit., p. 74,
1854.

— _ Cotteau. Paléontologie Frangaise, t. vii, p. 274, pl. 1065,
figs. 3—14, 1862.

Test elevated, melon-shaped. Ambulacra nearly straight, narrow, depressed. Six
rows of small granules, the marginal the largest and most regular, the inner small, with
intermediate smaller ones. Inter-ambulacra wide, seven or eight large plates in each
column ; areole wide, circular, with a marginal circle of very small granules; boss smooth
or slightly crenulated ; tubercles small and perforate; sutures well marked, depressed.
Spines long, cylindrical, several-ridged ; ridges irregular towards the base, and serrated,
the interstices granulated.

Dimensions.—Height, one inch and eight tenths; transverse diameter, two inches.

Description —tThe test of this fine urchin is high and melon-shaped, and reminds me
of C. maximus, from the Coral-rag of Germany. ‘The ambulacral areas are narrow,

FROM THE WHITE CHALK. 63

nearly straight, and provided with six rows of small granules ; the marginal series are the
largest, the inner ones are small, and between them are some still smaller granulets
scattered about the area. The poriferous zones are only gently waved, the holes round,
and placed transversely; there are fifteen pairs opposite each of the equatorial plates.
The inter-ambulacral areas are very regularly formed; the plates, about eight in each
column, are large and uniform; the areolz are wide and circular, and occupy the entire
depth of the plate; the margin is surrounded by a circle of very small mammillated
granules, about twenty-one in number, and well spaced out from each other; the boss is
not prominent, and only some of the summits are feebly crenulated, whilst the others are
smooth. The tubercle is small, and deeply perforated (fig. 2, a, 4). The miliary zone is
wide, and depressed in the middle; the granules are fine, homogeneous, and nearly equal-
sized, and arranged in régular horizontal rows, which follow the angles of the median
sutures. As the areolz occupy the centre of the plates, there is a considerable granular
space between the ambulacral side of the areolee and the poriferous zones. ‘The sutures
are all very distinctly marked, and the median inter-ambulacral is much depressed. The
peristome is sub-pentagonal and large. The spines are long, cylindrical, and sub-acumi-
nated at the summit (fig. 4, a). The stems are provided with long, narrow spines, projecting
at intervals from many regular, longitudinal ridges, and having the interstices finely
granulated (fig. 4, ¢). For the most part these spines are equally and uniformly disposed ;
sometimes, however, they lose their homogeneity, and vary in their height and in pre-
serving a longitudinal disposition. The valleys between the ridges on the stem are
throughout covered with fine, delicate, microscopic, sub-granular, longitudinal strize, which
are only visible by the aid of a lens (fig. 4, ec). The neck is without ridges and spines ;
the collar is long and finely striated, and separated from the stem by a distinct line (fig.
4, 6). The head is large, the milled ring prominent, with thicker striz than those on the
collar, and the rim of the acetabulum is smooth (fig. 4, 4).

Affinities and differences.—The melon-shaped test, very regular inter-ambulacral areas,
areolee and tubercles gradually increasing from the base to the upper surface, added to the
long, slender spines, with prickly ridges, serve to distinguish this species from its congeners
of the White Chalk. The spines resemble those attributed to C. spenigera, Cott., of the
Neocomian stage, from the middle of France, but they manifest differences which are
sufficiently distinctive of each. In C. peroruata the spines arise from ridges at regular
intervals, which are absent in C. spinigera.

Locality and Stratigraphical position.—This species was collected from the White
Chalk of Kent and Sussex. The specimens figured are from the cabinets of Dr. Bower-
bank and Rey. T. Wiltshire.

The foreign localities of this urchin are, according to M. Cotteau, Vernonnet,
Giverney, Pinterville, Houguemarre (Eure), Epagny (Somme), Tartigny (Oise), La Fléche,
(Sarthe) ; where the spines are common in the Etage Sénonien.

64. CIDARIS FROM THE WHITE CHALK.

History.—The late Frederick Dixon, Esq., F'.G.S., and Professor Forbes, first figured,
in 1850, the test and spines of this species from the White Chalk of Sussex, and the latter
described it as a new species under the name C. perornata. . M. | Abbé Sorignet described
the spines which he collected in the department of the Eure under the name C. dongispinosa,
and Professor d’Orbigny those found in the Sarthe as C. Sarthacensis. As Professor
Forbes first figured and described the urchin, and the other authors only described it, the
name of the figured specimen is for this reason retained.

Ciparis HirupDo, Sorignet, 1850. Pl. X, figs. 1—5; Pl, IX.

CIDARIS HIRUDO, Sorignet. Ours. Foss, de l’Eure, p. 17, 1850.
— SCEPTRIFERA, Forbes, in Dixon’s Geol. of Sussex, p. 338, pl. xxv, figs. 32 and 33,
-- — var. SPINIS TRUNCATIS. 1890.

— SULCATA, Forbes, in Morris’s Catal. of Brit. Fossils, 2nd edit., p. 75, 1854.

— _ Woodward. Mem. of Geol. Surv., Decade vy, explanation of pl. v,
p. 3, 1856.

— _ HIRUDO, Cotteau. Paléontologie Francaise, tom. vil, p. 244, pl. 1054,
figs. 6—16.

Test, in general, of moderate size, sometimes large, slightly depressed equally at both
poles ; ambulacral areas narrow, flexed, with six rows of granules at the equator, dimin-
ishing to two at the apertures ; in the two external rows the granules are larger and mam-
millated, in the inner rows they are very regularly disposed, but smaller and unequal ;
poriferous zones very narrow, depressed, and_ flexed, and formed of small round pores,
the intervening septum having a slight divisional elevation; inter-ambulacral areas wide ;
columns with five or six large plates; areola moderate, depressed, margin elevated, and
surrounded by a circle of mammillated granules, well spaced out apart; boss with a
smooth summit ; tubercle moderate in size and perforated, the areole and tubercles in-
ereasing gradually in magnitude from the peristome to the upper part of the columns;
miliary zone depressed in the middle, and filled with equal-sized granules; line of the
sutures well marked throughout.

Spines elongated, cylindrical, sabfusiform ; stem enlarged at the middle, and tapering
at the upper third, summit truncated and presenting a stellate figure ; the longitudinal
ridges on the stem have a granuliform structure, and the intervening valleys are finely
chagreened ; the neck is short, distinctly defined, and marked with longitudinal microscopic
lines ; the head is small, the milled ring prominent, and the acetabulum has a smooth ring
around the brim.

Dimensions.— Specimen Pl. X, fig. 2—height, nine tenths of an inch; transverse
diametér, one inch and four tenths. Specimen Pl. [X—height, one inch and three
tenths; transverse diameter, one inch and nine tenths (?).

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PLATE I.

Cidaris from the Gault and Grey Chalk.
Ciparis Carter, Forbes, 1854.

From the Grey Chalk.

. Upper surface, showing the disc, natural size. From the collection of James Carter,

Esq: .»P.-39.

Lateral view of the same, showing the height of the test and the prominence of the
discal elements.

A single inter-ambulacral plate, with a portion of the ambulacral area and poriferous
zones, magnified.

. Ajfical disc, with the ovarial and ocular plates, magnified.

Portion of a spine, magnified.

A small ambulacral spine, magnified.

Ciparis GauLtina, Forbes, 1854.

From the Gault.

. ‘Test and spines, 7” si¢v. British Museum. P. 36.

. Inter-ambulacral plate, magnified two and a half times.

One large primary spine, natural size.

. A portion of ditto, near the base, magnified twice.

Stellate terminal portion of a primary spine, magnified.

A primary spine, natural size.

. The same, magnified twice.

. A primary spine, with expanded stem.

6. The same, magnified twice.

. A view of the terminal portion.

Printed by Hullmandel & Walton

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PLATE II.

. Cidaris from the Upper Greensand and Grey Chalk.
Ciparis BowErBANkil, Forbes, 1850.

From the Grey Chalk.

1 a. Test and spines, iv situ, natural size, belonging to Dr. Bowerbank, F.R.S.- P. 45.
b. An inter-ambulacral spine, magnified three times.
c. The head, milled ring, and neck, highly magnified.
d. A small ambulacral.spine, highly maguified.

CIDARIS VELIFERA, Broun, 1857.

From the Upper Greensand.

A lateral view of the test, natural size, in the collection of W. Cunnington, Esq., F.G.S._ P. 37.

2 4a.
6. Basal portion of the same, magnified twice.
_e. Dorsal portion of the same, magnified twice.
d. Lateral view of the same, magnified twice.
e. Inter-ambulacral plate, a portion of the ambulacra and poriferous zones, magnified five times.
f. A lateral view of a prinary tubercle with its circle of areolar granules, magnified.
3 a. One of the inter-ambulacral spines, natural size.
6. The same spine, magnified twice.
4 a, CIDARIS VELIFERA, a portion of the test and spines, im sifu, natural size. This unique specimen is

in the cabinet of Mr. W. Cunnington.
b. The head of a spine, with its milled ring, highly magnified.

Ciparis vESIcULOSA, Goldfuss, 1826.

From the Upper Greensand and Grey Chalk.

5 a. Upper surface of the test, natural size. This specimen from the Upper Greensand is in the possession
of W. Cunnington, Esq., F.G.8. P. 41.
6. Basal portion of the same test, natural size.
ec. Lateral view of the same test, natural size.
An inter-ambulacral plate, with ambulacra and poriferous zones, magnified three times.

Crparis Farrinepvonensis, Wright, 1864.
From the Lower Greensand.

6, 7. - Single infer-ambulacral plates from the Sponge-Gravel, near Farringdon, magnified two diameters.
Museum of Royal School of Mines.

8a,b,e. Different inter-ambulacral spines of this species. Museum of Royal School of Mines.
e, a. Basal portion of one magnified three times,

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Printed by Hullmandel & W

PLATE III.

Cidaris from the Red and Grey Chalk.

CrpaRIis VESICULOSA, Goldfuss, 1826.

From the Grey Chalk.

. Under surface of a large test, Grey Chalk, Dover, natural size. British Museum.

P. 41.

. The under surface of the same test, natural size.

. A lateral view of the same test, natural size.

One inter-ambulacral plate, with a portion of the ambulacra and poriferous zones,
magnified three times.

. A primary tubercle, magnified.

. Test of Crparis vestcunosa (?), from the Red Chalk, under surface, natural size.

In the collection of C. B. Rose, Esq., F.G.S.

. Upper surface of the same test, natural size.

Inter-ambulacral spine from the Red Chalk. In the collection of C. B. Rose, Esq.,
F.G.S.

Ditto ditto ditto.

6. Portion of the same, magnified three times.

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CipARIs DISSIMILIS, Forbes, 1854.
From the Lower Chalk.

Upper surface of the test, natural size. In the collection of Rev. T. Wiltshire, F.G.S.
P. 46. ;

. Under surface of the same test, natural size.

Lateral view of the same test, natural size.

. Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three times.
. A single tubercle, magnified.

Portion of an inter-ambulacral spine, magnified.

. An ambulacral spine, greatly magnified.

Printed by Hillmandel & Walton

CRBone del. et hth

PLATE III a.

Ciparis pisstminis, Forbes, 1854.

From the Grey Chak.

“1a. Upper surface of the test, with spines attached, natural size, from the late Mr.

Taylor’s collection, now in the British Museum, p- 46.
4. Portion of an inter-ambulacral spine of this species, magnified several diameters.
British Museum.
2 a. Vest and spines, upper surface, natural size, belonging to the Rev. T. Wiltshire, F.G.S.
4. Test and spines, under surface, natural size, ditto, ditto.

c. Penultimate inter-ambulacral plate from the upper part of the column, showing the

obsolete tubercle and areola.
- d. Inter-ambulacral spine, natural size.
e. Portion of the stem, neck, and head, of the same spine, magnified several times.
f. Portion of another smaller spine, magnified.

g. Ambulacral spines, natural size and magnified.
3 & 4. Inter-ambulacral spines, natural size, Rev. T. Wiltshire’s cabinet.

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5. A small test and spine, natural size, ditto, ditto.

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PLATE IV.
CIDARIS CLAVIGERA, Konig, 1822.

From the White Chath.

Two tests, with spines, in one block of chalk, natural size. From the late Mr.
Taylor’s collection, now in the cabinet of Dr. Bowerbank, F.R.S._ P. 48.

Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three
diameters.

A large tubercle, and circle of areolar granules, magnified.

The apical disc, with the ovarial, ocular, and anal plates iv situ, magnified two
diaineters.

A large inter-ambulacral spine of a typical form, natural size.

The same, magnified two diameters.

A portion of the neck of the same, magnified three diameters.

A large spine of an abnormal form, natural size.
A large spine of an abnormal form, magnified two and a half diameters.

A portion of the neck of the same, magnified three diameters.

Different forms of inter-ambulacral spines, from a series in the collection of
Dr. Bowerbank, F.R.S.

The neck, milled ring, head, and acetabulum of the specimen figured at’ 3 a,

magnified four diameters.
A small ambulacral spine, highly magnified.
Another ambulacral spine, highly magnified,

Printed by Hullmandel & Walton

C.R Bone, del et ith

PLATE V.

CIDARIS CLAVIGERA, Konig, 1822.

From the White Chalk.

Test, with dental organs and spines, natural size. From Mr. Taylor’s collection,
now in the British Museum. P. 48.

. Lateral view of a fine test, natural size. British Museum.

The under surface of the same, natural size.

The apical dise, showing the ovarial, ocular, anal plates, and madreporiform body,
magnified two and a half diameters. British Museum.

A portion of the peristomal membrane and oral plates, with part of the dental
organs, magnified two and a half diameters. British Museum.

. An abnormal inter-ambulacral spine, natural size. British Museum.

The same, magnified, to show the position and form of the canals passing through
_the stem.

An abnormal spine, with summit excavated, natural size. This specimen belongs
to the Rev. T. Wiltshire.

7—14. Varieties of large inter-ambulacral spines, belonging to the British Museum,

15.

LG;

iia.
b.

natural size. British Museum.

A remarkable abnormal form, with an enlarged neck and conical stem and apex,
natural size. British Museum.

CIDARIS SCEPTRIFERA, Mantell, 1822.
From the White Chalk.

Upper surface of a fine test, natural size, with the apical disc im situ. This
specimen belongs to Dr. Bowerbank’s collection. P. 54.

Under surface of the same, natural size.

Lateral view of the same. _

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C.R. Bone del et lith Printed by Hullmandel & Walton.

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PLATE VI.
CIDARIS SCEPTRIFERA, Mantell, 1822.
From the White Chalk.

Upper surface of the test, natural size. This magnificent specimen belongs to the
~ British Museum. P. 54.

Under surface of the same, natural size.

Lateral view of the same, natural size.

Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three dia-
meters.

The uppermost plate of an inter-ambulacral column, showing the curious rudi-
mentary tubercles, and areola thereon, magnified two diameters.

The uppermost plate of the adjoining column, magnified two diameters.

A portion of the apical disc, consisting of one ovarial, two ocular plates, and three
anal plates, magnified two diameters. The entire disc is seen iz sity, in
fig. 1a. |

Three anal plates, magnified two diameters.

Test with spines, natural size. This specimen belongs to the Museum of the

Royal School of Mines.

Spine, type form, natural size.
The upper part of the stem, magnified three diameters.

The stellate form of the terminal extremity, magnified three diameters.

Spine, type form, natural size.
The head, neck, and milled ring of the same, magnified three diameters.

. Another spine, natural size.

A variety. Specimens 3, 4, 5, and 6, belong to the British Museum.

C.R Bone del. et th Printed by Hullmandel & Walton.

PLATE VIL.

CIDARIS SCEPTRIFERA, Mantell, 1822.

From the White Chalk..

Fig.
1 a. Test, dental organs, and spines, zz si¢w, natural size. From the late Mr. Taylor’s
collection, now in the Museum of the Royal School of Mines. P. 54.
6. Dental apparatus and teeth, magnified two diameters.

ce. Ambulacral spine, greatly magnified.

2. Spine of C. sceptrifera, variety. From the cabinet of the Rev. ‘I’. Wiltshire, F.G.S.

CIDARIS PERORNATA, Forées, 1850.
From the White Chath.

3 a. Lateral view of the test, natural size. In the British Museum. P. 62.
6. Under surface of the same, natural size. .
ec. Interambulacral plate, ambulacra, and poriferous zones, magnified three diameters.

d. Lateral view of a primary tubercle, magnified.

4a, Inter-ambulacral spine, natural size. Museum of the Royal School of Mines.
6. Stem, neck, head, and milled ring, magnified three diameters.
ce. A portion of the stem, magnified six diameters, to show the spiny ridges and the

longitudinal lines in the valleys.

Phe vall

C.R.Bone, del et hth.

‘Fra.

PLATE VII a.
CIDARIS SCEPTRIFERA, Mantell, 1822.

From the White Chalk.

. Test and spines, C. sceptrifera, var. filosa, from the White Chalk of Gravesend, natural

size, presented to the British Museum by the Rev. Norman Glass, F-G.S. P. 54.

: Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three diameters.

A thickened variety of spine, magnified two diameters.

Spine of C. sceptrifera, var. tilosa, belonging to the Rev. Thos. Wiltshire, F.G.S.

CIDARIS PERORNATA, Forbes, 1850.

From the White Chalk.

. Under surface of a iio C. perornata, restored from the Rey, Thos. Wiltshire’ S

specimen, now in his cabinet. P. 62.

_ Lateral view of the same.

3 . F
- i I ete FO ST ee ee ee we

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PLATE VIII. °

Ciparis Mercrys, Cotteau.

From the White Chalk.

. Under surface of the test, natural size. In the possession of Dr. Bowerbank, F.R.S.

P. 60.

. Lateral view of the same, natural size.
. Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three diameters.
. A lateral view of the same plate, magnified three diameters.

. A penultimate plate, from the upper part of one of the inter-ambulacral columns,

showing the small rudimentary tubercle and areolz, magnified three diameters.

A small inter-ambulacral plate, near the peristome, magnified three diameters.

. A portion of an ambulacral area, and poriferous zones, magnified five diameters.

a. Inter-ambulacral spine, natural size.

A portion of the stem, magnified two and a half diameters.

. The head, neck, and part of the stem, magnified two and a half diameters.

A small inter-ambulacral spine, natural size.

CIDARIS SUBVESICULOSA, d’ Orbigny.
From the White Chalk.

Upper part of the test, and apical disc with one spine, 2 s?/w, natural size. From
the collection of Dr, Bowerbank, F.R.S. P. 57.

A plan of the apical disc, showing the parts ox are absent in the pissetiig

figure.
Lateral view of a smaller test. Dr. Hodersanl’s Satind

An ambulacral spine, gaghly magnified.

“ae §

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ers Sa eee ee) oe

-
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PLATE XI.

> CIDARIS SERRIFERA, Forbes, 1850.

From the White Chalk.

. Test and spines, natural size. Collection of Henry Willett, Esq., F.G.S. P.51.

. Under surface of the same test, natural size.

- Lateral view of the same, natural size.

. Inter-ambulacral plate, ambulacra, and poriferous zones, magnified three diameters.

. Inter-ambulacral spine, natural size.

Stem, neck, and head of the same, magnified three diameters.

. Portion of the stem, highly magnified, to show the serrated spines and intervening

sulci. In the cabinet of Dr. Wright.
Ambulacral spine, highly magnified.

Portion of a spine of. C. serrifera, magnified. Collection of Professor 'Tennant, F.G.S.

.. Spines of Cidaris. British Museum.

4. One of the spines, magnified two diameters.

Ciparis Drxont, Cotteau, 1862. Inter-ambulacral spine, natural size. From the
_. Grey Chalk of Dover. Collection of Henry Willett, Esq., F.G.S.

. A section of another specimen, to show the cavity in the stem.

CipaRis PLERACANTHA, Agassiz. Spine, natural size. British Museum.

Spines of Cidaris, natural size, and magnified twice. British Museum. -

C.R Bone det et hth

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PALMONTOGRAPHICAL SOCIETY.

INSTITUTED MDCCCXLVII,

MDCCCEXIV.

ANGINA GaaReR!
: i a ee ee ae el er

~_ ico 4 ne BA Dy -_ an,

A MONOGRAPH

BRITISH TRILOBITES.

BY

od W. SALTER, ALS. F-.G-S.,
TATE OF THE GEOLOGICAL SURVEY OF GREAT BRITAIN.

LONDON:
PRINTED FOR THE PALHONTOGRAPHICAL SOCIETY.
1864.

eee

>
J. E. ADLARD, PRINTER, BARTHOLOMEW C
: ero

oteem toe

LOSE.

4

CoRRIGENDA.

In page 14, line 18, for Emmerich, “ 1845,” read “1839.”

pF)

9

Poe (OTe Osten ed ONGas

37, at bottom, add the following synonym:

“Cuasmors Opint, Hoffmann. Trilob. Russlands Verhandl. Kaiserl. Miner. Gesellsch

zu St. Petersburg, 1858, t. iv, fig. 7.
39, for “fig. 7,” read “fig. 9.”
44, line 4, for “VII,” read “ VI.”
59, ,, 3, add synonym, “Salter, in Decades of Geol. Survey, No. 2, Article P. caudatus,
p. 8, (see line 16).”

64, line 13, omit fig. 10.

*

e* on

‘ im
ars + ge af eee ah:

ero as ~ ‘
von fet, hey

A MONOGRAPH

OF

Plek TITS HT «PR LO Ba TEA.

A Monoeraru.of the British species of the Trilobite group has long been desirable,
and would, in accordance with the wish of many friends, have been prepared by me
before now, had public engagements permitted it.

The materials for such a work have hitherto been much scattered; nevertheless, of
late years, they have become very numerous, whilst the publication of such sterling works
as those of Barrande, Burmeister, Beyrich, and Lovén, have disposed naturalists, as
well as geologists and collectors, to pay increased attention to the group,

I think that a true and natural arrangement of the Trilobites is yet to be given; and
therefore prefer at present to publish the materials in hand, that im the mean time
systematic zoologists may have the means of forming their judgment. The group is avery
complete one, and no artificial scheme is admissible for its classification. Dr. Emmerich’s
Essay, of 1845, seems to me to be the nearest approach to a natural grouping of the
families ; and I shall follow it meanwhile, in figuring the species,’ with such additions as
are proposed on the next page. The dichotomous arrangement here given is proposed
merely as temporary ; but I believe it to be, in the main, a natural one.

And I trust that, by the time we have arrived at the conclusion of the work, some new
and clearer light may be thrown on the affinities and arrangement of this order of
Crustacea, as unique in character as it is well defined in geological place.

' Our friends will much oblige by forwarding us their best specimens, including any illustrative
fragments, in the order of the families as given on page 2. In that way all the materials for a genus will
be under the eye together, and no long detention of the specimens need take place. They may be sent to
my care, at Mr. Sowrrsy’s Natural History Offices, 45, Great Russell Street, London.

]

PRELIMINARY CLASSIFICATION oF triLositss,

I have here given chiefly British genera as examples. ‘There are, of course, many others.
It is evident that the lowest and most rudimentary group of all is that of the
Agnostide, which, therefore, may be at once placed at the base; and there is not likely to
be much difference of opinion as to the placeof the Phacopide, as the typical and most

perfect group of the order.

The other genera fall more or less naturally into an inter-

mediate place, but are developed along two distinct lines, as follows :

A.—Trilobites with facial su-

1. PHACOPIDZ.

ture ending on the ex- Phacops. Trimerocephalus.

ternal margin. Eyes well Acaste. Chasmops.

developed, usually fa- Odontochile.

cetted externally. (Pha- Crypheeus.

copini.) 2 CHEIRURIDZ. 7 12. PROETIDZ.
Cheirurus, Staurocephalus. ? Cybele. i Brachymetopus. Griffithides.
Spheerexochus. Deiphon. ? Encrinurus, / Phillipsia. Proetus.
Amphion. ? Zethus. vA Phaeton.

B.—Facial suture ending on
the posterior margin.

Eyes (usually) mode-

rately developed, smooth,

3. ACIDASPIDZ.
Acidaspis, &c.

4. LICHADZ.
Lichas,

11, BRONTEIDZ,

Bronteus.

(Asaphini.)
10. ASAPHIDZ.
7. CALYMENIDA, 5. CYPHASPIDZ. Illenus. —_Nileus.
Calymene. Cyphaspis. Stygina. Isotelus.
Homalonotus. Aulacopleura, &c. Asaphus.
Ogygia.

8. CONOCEPHALIDA. 6 HARPEDIDZ. Barrandia.
Conocoryphe. Sao. Harpes. Basilicus.
Solenopleura. ? Centropleura. Niobe.
Holocephalina. Angelina. Psilocephalus,

9. OLENIDZ. Remopleurides. =
ZA Olenus. Triarthrus. A®glina &
% Spheerophthalmus. Tiresias. ogee
% Paradoxides. Cyphoniscus. § &
So yphoniscu gs
ee Anopolenus. Hydrocephalus, = #
% &% —_ C,—Facial sutures obscure, or 13. TRINUCLEIDE. £35
%. S submarginal, or none. Dionide. Trinucleus, = s
eres Eyes often absent. (Am- Ampyx. BS &
@ 2 sic Sr =
S %. pycini). s ae
on % D.—Without eyes or 14. AGNOSTIDZ. S. <
% facial suture. Agnostus, aS <
(Agnostini.) Trinodus.
J. W.S

March, 1864,

BREPESEM TRELO BITES:

History.—Professor Burmeister has given a very full account of the authors who
have written upon this subject, in his celebrated treatise on the ‘ Organisation of Trilobites,’
published at Berlin in 1843, and translated for the Ray Society by Prof. Thomas Bell and
the late Prof. Edward Forbes.

A short summary of the Professor’s observations will be sufficient for our purpose, for
the book is widely circulated, and is indeed the only summary to which we can turn for
full information. He has enriched it with a full bibliography collected by himself, and
traced the work done by successive naturalists and geologists to the time of Emmerich’s
scientific treatise in 1839,’ and Milne-Edwards’ Catalogue, in his volumes on the
‘ Crustacea.’

It would seem that our own countryman Dr. Llhwyd was really the first to call attention
to the ‘regularly figured stones lately found by him,” but though he referred them to “ the
sceletons of some flat fish,” he took good care to explain that ‘not these or any other
marine terrestrial bodies were really parts of animals,” and he only marvelled that the
‘“‘Piscis Icon” should be raised above the surface of the stone “ac s¢ verus piscis esset.”
This view of the fossils was about as correct as most of those which followed till the time
of Linneus, although Mortimer and Da Costa had declared in favour of their crustacean
origin. It was Walch’s ‘ Natural History of Petrifactions,’ published at Nuremberg in
1771, which first brought into a focus the scattered information regarding the group, and
established the views of Da Costa, Linnzeus, Wilckens, and other writers who had regarded
Trilobites as entomostraca. Walch first gave them the name of Trilobites, and Parkinson’s
figures and the descriptions of several German authors pointed out the necessity of dis-
tinguishing the species.

1 Reproduced with improvements in 1845. This is the earliest scientific arrangement of the tribe :
See Leonhard und Bronn’s ‘ Jahrbuch,’ 1845.

4 HISTORY

In 1821, two distinguished French naturalists entered this field. Latreille, whose fame
as astudent of the Articulata needs no illustration, strangely enough overlooked the manifest
characters which placed the Trilobites among Crustacea, and pronounced for their affinity
with Chiton. Audouin, on the contrary, compared them with the Isopod Crustacea,
declared they had no feet, but appendages for breathing organs, and, in short, led the
way, as Burmeister admits, for all subsequent research in the same direction.

Then followed Wahlenberg’s work, and Brongniart’s ‘ Histoire Naturelle des Crustacés,’
a work in which the genera of Trilobites were first defined, and seventeen species
described. Schlotheim soon raised these to twenty-six, and Dalman’s complete treatise
on the group in 1826 gave a new importance to the subject ; while the very perfect state
of the Swedish specimens enabled him to present better figures than had before appeared.
He called the group Paleade, and altered some of the generic names without much
reason, but in this he has not been followed.

De Kay in America, and Count Sternberg in Germany, meanwhile, described many
forms ; and Hichwald and Razumousky, in Russia, prepared the way for Dr. Pander’s careful
treatise, in which the labrum, first observed by our countryman Charles Stokes in American
specimens, was fully described.

Dr. Green’s monograph, in 1832, was only valuable for the casts which illustrated it ;
and up to the time of the publication of the ‘ Silurian System,’ in 1837, but very little was
known about Trilobitesin England. That work, however, had a wide fame, and deservedly
so, and by costly illustrations of the best specimens procurable, and by the philosophic
remarks contributed by Dr. McLeay, gave a new impetus to the collection and description
of the species. Dr. Buckland, a year before, had illustrated some of the more common
kinds-in his ‘ Bridgwater Treatise.’

But the period was now coming for the scientific arrangement of the facts collected.
Illustrations were abundant both in England and on the Continent, especially in Sweden
and Norway, where Sars and Boeck, Esmark, Hisinger, and other authors, had done their
best to make the Scandinavian species known. About 1837 Prof. Burmeister began to
turn his attention to the group, and Dr. Quenstedt, of the Mineralogical Museum of
Berlin, published some important observations with regard to the number of rings in the
body, which Burmeister justly regards as of great consequence. It is doubtful whether
the honour belongs to Burmeister or Quenstedt of first calling attention to this, the chief
means of distinguishing the various genera, as well as a point of great importance in
determining the affinity. Dr. Burmeister, at all events, suggested it to Quenstedt, and
afterwards worked it out, considering that Trilobites differ from all other Entomostraca in
having no definite fundamental number of segments to the thorax, while the living Ento-
mostraca and Malacostraca are ruled by different but always definite numbers.

While these investigations were going on, Dr. Emmerich succeeded Dr. Quenstedt in the
care of the Berlin Museum, and followed out his researches by a complete and beautiful
essay, well known as the ‘ Dissertatio Inauguralis,’ Berlin, 1839. In this work the author,

OF TRILOBITES. 5

while ranging over the more recondite portions of the study, threw for the first time the
whole Trilobite group into a series of natural families. And these must be, I conceive, the
basis of any true classification of the order Zi/obzta. The separation of the large-eyed
Trilobites with eleven body-rings, was not indeed due to Emmerich, but to Quenstedt ; but
Dr. Emmerich’s essay confirmed this important view, named the group Phacops—our first
described one, and went on to apply the principle thus gained to the arrangement of the
whole. The species are carefully made out, the synonyms collected, and a model set for
all succeeding works.

Other observers were not idle. Von Buch, Bronn, Green, Goldfuss, and Miinster were
figuring the new species with various merit; and Milne-Edwards had compiled all the
known synonyms in his great work on the Crustacea. In 1843, three most important
works appeared, in one of which Dr. Burmeister placed before the German reader all the
facts regarding the history, structure, and affinities of the group, while Dr. Goldfuss gave
a systematic arrangement of Trilobites and description of new species in the ‘ Jahrbuch’
for 1843. In England, the profound and careful work of the late Gen. Portlock first
called attention to all the new discoveries which had been making abroad, while the many
new forms which he described and illustrated’ have given his work the very highest rank.
The American species began now to be figured by Hall, and Emmons, and Vanuxem ;
Lovén was producing his classic descriptions in the Transactions of the Swedish Academy.
(Ofvers. Kongl. Vetensk. Akad., 1844, &c.) ; Emmerich repeated and improved his classi-
fication in the ‘ Neues Jahrbuch’ for 1845; Dr. Beyrich, in 1846, was giving us his
accurate descriptions of species ; and in the same year appeared the ‘ Notice Préliminaire ’
of M. Barrande, the herald of a work which has thrown nearly all other works on trilobites
into the shade.

This remarkable sketch by M. Barrande, the fruit of thirty years of labour, indicated
at once the commencement of a new era for the group. A supplement published by M.
Barrande the same year raised the number of described Bohemian species alone to 152.
The rich “terrain” which M. Barrande has so emphatically made his own still furnished
abundant work for Beyrich; and M. Corda, the keeper of the National Museum at Prague,
even attempted to snatch the “ spolia opima” from the hand that had won them. The
‘ Prodrom einer Monographie der Bohmischen Trilobiten,’ while it attests the rapid industry
of the well-known botanist of Prague, shows how little is gained by hasty generalisation,
and especially “‘ appropriation ” in natural history. It was a melancholy failure. While
M. Barrande had patiently traced the metamorphosis of some thirty different kinds of
Trilobites, and was preparing for their illustration, these young and undeveloped Trilobites
were figured by Corda as so many distinct genera and species. A certain number of new
forms were doubtless named, and a few errors of nomenclature corrected; but the absurd

1 His illustrations do not do him justice. Owing to a misfortune of the printers, the whole of the
beautiful plates drawn for the work by Mr. G. VY. Dunoyer had to be hastily transferred by an employé,
and the character is greatly lost in the transfer.

() HISTORY

mistake of grouping the Trilobites according to the pattern of their tail-fringes, instead of
following Emmerich’s natural arrangement, was committed in presence of such materials
as Emmerich probably never saw !

Angelin’s first instalment of the Swedish Trilobites, appeared in 1852, after many
memoirs by Beyrich, and Lovén, and Kutorga, and Volborth, on the Swedish or Russian
forms ; but it is impossible to notice all the works that followed Emmerich’s essay. M‘Coy,
and Fletcher, and Prof. Wyville Thomson, and myself, have done our best, as opportunity
offered, to illustrate the British forms after Portlock’s model in 1843. The Decades of the
survey by EH. Forbes and J. W. Salter appeared in 1849 and 1853. In the last-named
year, M. Barrande’s long-expected volume made its appearance, and in its illustrations and
descriptions of 250 Trilobites is a work without a rival. He is now preparing the second
volume, which will add some fifty or sixty more. But as he will be referred to in
every chapter that follows, it is not necessary to say more of his work here. On one
point only has the author left the field open. He has honestly and modestly stated that
he does not profess to classify the Trilobites ; and on this point we are therefore free to
follow Dr. Emmerich as before.

The years 1855 to 1863 have seen great additions to our knowledge of Trilobites made
from all quarters: the primordiai zone has yielded up its treasures to the search of English
and American geologists, and has received additions from all parts of North Europe.

A formation utterly unknown to science till Barrande established its history
has proved to be a most extensive and rich repository for Trilobites. Barrande in
Bohemia and Spain, Angelin in Sweden, myself in Britain,—Logan and Dale Owen, and
Billings, and more lately James Hall, in the New World, have contributed materials from
this most ancient zone of life—the Cambrian. And if of late years systematic classifi-
cation has not kept pace with the description of the forms, the fault has not been with
the paleontologist in neglecting to supply the data.

Gro.ocicaL Prace.—The geological history of the Trilobite group is very clear and
succinct. Though not the oldest animal forms known, they meet us in the earliest forma-
tion in which we have any abundant traces of marine life, viz., the Lingula-flags
(Cambrian of Sedgwick, Upper Cambrian of Zye//, Lowest Silurian of Murchison).

In this their commencement we have some of the smallest and most rudimentary, as
well as some of the largest forms ; but the group did not attain its maximum, nor rise to
its most perfect forms, till the period of the Llandeilo and Caradoc formations—the
typical Lower Silurian deposits.

Above this point few new types were introduced; and though individuals were
numerous and species most abundant, there were fewer gezera in the Upper than in the
Lower Silurian. In the Devonian the reduction went still further. In the Carboniferous
Limestone they were reduced to three genera; and the group was extinct before the later
portion of the Coal-period.

As the Trilobites will be constantly referred to the special groups of beds in which

OF TRILOBITES. 7

they occur, it may be well to give, in a short tabular form, the Palzeozoic arrangement fol-
lowed in this work, with the distribution of the Trilobites as to maximum and minimum in
these zones.

The Paleozoic groups are nearly those adopted of late years by our leading geologists.
For the determination of the lower ones we are almost equally indebted to Murchison and
Sedgwick, and their labours since 1831 have now become the common property of the
scientific world.

GROUPS. UPPER PALZOZOIC. TRILOBITES,

Magnesian Limestone, &c, ............
None

PRR UUPANE irc ceany ap oat Pontefict Sandatane

Lower Coal Measures
Millstone: GriGee © sas osesen see nese es

Upper Coal Measures .................
f Upper CARBONIFEROUS }
|
2
|
1

Noredales Rocks) yc... cccitntascetecces's

L Lower CARBONIFEROUS ! Mountain Limestone ..,................
Carboniferous Slate

“SNOUTAINOLAVD

LUT OR
ie]
~
=F
o
3
O.
3
s
pS
=
@

MIDDLE? PALZOZOIC,'

Pilton and Marwood group (Upper

Uprer DEVONIAN ...... { Old Red Sandstone).................. ; Few genera; few species.
PCGHEEWIT BTOUP . .. occccasscecssesis oe:

eee group (Middle Old Red

TANI
Mippiz Devon Sandstone)

Few genera; many species.

ee i er ei,

"NVINOATQ

eo oO

Linton and Fowey group (Lower Old
Tats DRCONTAN oie: | Red, Sandatonie ers. decisietnoes se ; Few genera; many species.
Ledbury Shales (Passage Beds)

LOWER PALZOZOIC.

Upper Ludlow (Murchison) .........
{ ames and Lower Ludlow =} Few genera ; abundant species.
chison)
Wenlock Limestone (Murchison) ... >}

| Wenlock Shale (Murchison) ......... j

1 Wanllione Limestone (Murchison). i Many genera; abundant species.

Denbighshire Grits (Sedgwick)

MUAY HELE 5.7... tesoce ee | May-hill Sandstone (Sedgwick); Up-
per Llandovery (Murchison)

“‘NVIUATIQ WAdd()

} Many genera and species.

1 This term is introduced in deference to published authorities. But the Upper and Middle Paleozoic

groups are together only equivalent to the Lower, and might well be all included under the one term
“Upper Palzeozoic.”’

8 GEOLOGICAL PLACE |

GROUPS. Lower Patmozorc,—continued. TRILOBITES.
( LEANDOVERY )o.)s.hse06- Lower Llandovery Rocks (Murchison) Many genera and species.
5 | | Caradoc Rocks (Murchison) ; Upper }
Sa ig OFC Gre RR Re Aree ;
SI | AR. Bala Rocks Gedgwiek) Sie coves \ Masinittd Hf specie vad pene@e
RM 4 Upper Llandeilo Flags (Murchison) ; |
& | LEANDEILG ......4-+.-2-.. { Lower Bala (Sedgwick) ............ is
S | Arenig group and Skiddaw group
cee AEN ses
L ARENIG ....eeeeee eens | iSeqguich) ppltey es ditandelle, + Abundant genera and species.
L Murchison; Quebec group, Lo- |
Cle 027: a A ee a AAS J
Upper Tremadoc (Salter) ............ é
ITREMADOG |r... .ace-eeeer M d ,
for ( ; Lower Tremadoc (Salter) ............ Me ne ee ae
e | ;
2 | Upper Lingula Flags (Sa/ter)......... :
BE SDUNTOG oy. marcia ; s ;
= j rigs { Lower Lingula Flags (Sedgwick) FON Snead Sea
Z|
L MON GMYINDE ees. tiene ser

| ot and Harlech Sandstones

ROCUGUUIEIE) teScstitwaee ctacer or ee One genus? one species?
Llanberis Slates (Sedgwick) .........

LAURENTIAN AND AzotIc Rocks.

Structure AND Hasirs.—Of their natural history I do not intend to say much
here, as I think it foreign to the purpose of this work to discuss such points at length,
the chief object of the Palzeontographical Society being: to collect accurate figures and
descriptions of the species of British fossils. I shall, at all events for the present, content
myself with very few remarks ; and chiefly for the use of the general reader.

I need only say, then, that Prof. Burmeister contends that Trilobites belong to the
Entomostraca, or lower division of the Crustacea, from the numerous (not definite) number
of the segments of the body, and is disposed to place them among the Phyllopoda. The
learned McLeay, in his discussion of their affinities in the ‘Silurian System,’ gave them a
higher position, intermediate between the Isopodous group and the Phyllopods ;’ and it is
pretty certain that they form a distinct order, and do not belong to any modern group
of Crustacea.

Every author who has written on Trilobites has more or less perceived their analogy
with the Limulus or King-crab, to which tribe there is, indeed, a good deal of external

' McLeay was, of course, not aware of the metamorphosis of the Trilobite, since made out by M.
Barrande. He characterises them as having the “head distinct, without antenne ; the feet rudimentary,
soft, and almost useless.” His judgment, as to their habits, is suggestive, and, at the same time very
cautious. He evidently thought it likely they had no feet at all; and I give his remarks in brief. ‘‘ Whether
they moved (they were probably to a certain degree sedentary) by soft, rudimentary feet, by undulation of
setigerous segments, as the worm moves, or by an undulation of the lower soft surface, as in Chiton, is
uncertain. They probably adhered in masses, as Chitons do; and, as the mouth is like that of Apus, they
were probably carnivorous, as is that genus, and may have fed on Acrita, Annelida, or naked Mollusca.”

OF TRILOBITES. 9

resemblance. But this resemblance totally fails when we examine the under side of the
animal ; for all the researches hitherto made (and they are many) fail to detect the slightest
trace of limbs in the Trilobite. It is impossible, seeing the state of preservation in which
they occur, to suppose that in every case,—in fine shale, in limestone, in arenaceous mud,—
all traces of these organs should have been lost, had they ever existed.

We are compelled to conclude that Trilobites had not even membranaceous feet, and
that the ventral surface was destitute of appendages. It is of course difficult to prove
this. And almost all naturalists are disposed to allow them soft gills, attached to the
under side. I do not see that the Trilobite had any need of appendages, further than what
might be necessary as breathing organs. In this I have the concurrence of Prof. Wyville
Thompson, who has given some thought to the affinities of the group. If gills existed at
all, they were probably quite minute.

There is some reason to believe that, like its predecessor, the Annelide, the habit
of the ‘Trilobite was to gorge itself with the carbonaceous mud, and extract from it the
nutritive portions. Such material has, indeed, been found in the straight intestinal canal
of the Trilobite. Barrande has figured a specimen in which this viscus is preserved, a
natural cast being taken of the interior by the sabulous matter swallowed by the animal.’
What the nature of this sabulous matter was originally may be matter of conjecture; but
it was solid enough to retain the stomach and intestine in a dilated form, while the sur-
rounding matrix was solidified. It must, therefore, have consisted of a hard food, such,
for instance, as the shells of Lingule, or, if the habit was carnivorous, of the contents of
the bodies of the worms devoured,—or, lastly, of the silty mud among which the creatures
lived. Against the former supposition we have strong reason to conclude, for Trilobites
certainly possessed no hard jaws capable of comminuting shells or corallines, which we
know existed during the same period. I see no likelihood of the carnivorous habit, and
venture the latter suggestion. Mr. Spence Bate also thinks the mouth was contractile.

The only hard portion of the under side is the immoveable upper lip or labrum; and
this may have been the instrument by which the food was scraped together. The
absence of feet, and the presumed nature of the food would give me reason for believing
that the Trilobite did not swim, as supposed by many authors, but crawled along the
bottom. The shape was fitted for this; all Trilobites, whatever be their ornament on
the upper side, present an even contour round the margin, which would apply itself to a
flat surface accurately, while the under side was no doubt smooth and soft.? Probably,
in many cases, the Trilobite lay half-buried in the silt, as is the frequent habit of the large
Limulus, or King-crab.

1 Tn the genus Trinucleus, vol. i, pl. 30, fig. 38, of the ‘Systéme Silurien de Bohéme,’ par Joachim
Barrande, 1852, Prague and Paris, vol.i. A magnificent and costly work, of which only the Trilobites
are yet published.

2 The analogy with Chiton, perceived by some of the old writers, is not altogether fanciful. At least,
the habit must have been very similar, though of course there is no direct relation.

2

10 STRUCTURE AND HABITS

I am indebted to Mr. Spence Bate for some friendly criticisms of these views, and
shall wait with interest for his promised memoir on the ‘ Homologies of the Trilobite,
and its Habits.’

The general structure of the animal will be best perceived by referrmg to the woodcuts
a little further on ; and while there is, in the greater part of this structure, a sufficient
resemblance to the ordinary Crustacea, there are one or two points in which the Trilobite
differs from all other groups, and they happen to be obvious ones.

The curious so-called facial suture, a line of division which is only faintly indicated in
the Limulus, and which has, perhaps, no other representative’ in the whole Crustacean
class, sufficiently distinguishes the ‘Trilobite. It divides the head into two portions, an
anterior one that bears the eye, and a posterior that covers the stomach. The latter
segment is much larger than the former, and may be formed of several rings.

And then there is the ‘‘trilobation.” Whatever tendency some of the higher
Crustacea may show to this, and in whatever degree a few of the Trilobites may lose it,
it is the conspicuous character of the whole order, and has, doubtless, an important
meaning. Limulus also shows a trace of this trilobation ; but it is accidental, rather than
characteristic, in other groups.

I give here a copy of the original figure in the ‘ Memoirs of the Geol. Survey,’ vol. ii,
Part I, p. 334. It is not drawn from any particular Trilobite, but is a general expression
of the structure.

And I have added one or two terms from Barrande’s more complete figures.

Fie.1. Fic. 2.

Beginning with the HEAD, or carapace (Fig. 1, upper side; Fig. 2, under side), we
recognize the following portions:
GuaBeLia (A), bounded by the axal furrows (A*), and including the neck-furrow (c) ;

' Tam bound to state that Mr. S. Bate believes he has discovered the analogue of this suture on the
under side of the crab and lobster; he finds it too in Argulus, &. But his views are not yet fully
published.

OF TRILOBITES. 11

the basal furrows (Z) ; middle or ocular furrow (e); upper or frontal furrow (/); with an
occasional pair of frontal furrows (/*). 2

These furrows bound and include the various lobes, designated thus: the frontal lobe
(2) ; upper or third lobe (2) ; middle lobe (4) ; basal lobe (gy); neck-lobe (4).

The sides or cuExEks consist of a portion fixed to the glabella (Bj 7 &) ; and separated
from the free or moveable cheeks (0 C) by the FactaL sutuRE (¢ q). ‘These moveable
cheeks bear the nyxs ; the fixed cheeks include the eye-lobe (r), the neck-furrow (c), and
in some cases the posterior angles (B), often produced into spines.

The posterior margin (/) is usually divided by the facial suture, which, in other cases,
cuts the outer margin at g.

The front margin of the head is sometimes produced into a point (4), and on its under

-side (fig. 2) shows the RosTRAL SHIELD (m), with its suture (/) (rostral suture) ; the
inferior branches of the facial suture (s s), the incurved under margin (¢), the LaBruM or
EPISTOMA' (#), and sometimes a cavity (P) for the reception of the ends of the pleure in
rolling up.

Each rHorax-rinG (fig. 3), in like manner, consists of the axis (A), with its articular
portion (4), divided by the axal furrows (A*) from the side-lobes or pleura. These last,
whatever be their nature, are in one piece with the axis, never articulated with it.

The rLevR# consist of a posterior portion (/), a fuleral or anterior portion (e), sepa-
rated by the deep pleural groove (¢7). Ate the fulcral points are seen, beyond which in
most genera the segment is facetted (a a), for rolling up. These facets (a a) are always
smooth, and slide under the preceding joint in the act of rolling.

Sometimes the terminal portion is produced into spines, (77).

The ratL, or pyerpr1um (fig. 4), consists also of an axis (A), with its articular portion, as
in the thorax ; the tims or lateral portion is either entire, as at (a*), or shows its component

' The exact nature of this piece is not quite certain. I use ‘labrum’ in the descriptions.

12 PHACOPIDA.

pleuree as at (4*). The furrows (4 4) correspond to the pleural grooves of the thoracic joints,
and the finer intermediate lines mark the sutures between the several segments of which
the tail is compounded. The anterior groove (A) is generally the strongest. The margin
(e) is mostly smooth and even, and often concave. At (/) the facet is seen on the front
edge; (/) is the mucro, either short or prolonged into a spine, and often absent altogether.
These are not all the points of structure visible on the crust of the Trilobite. But it
is desirable not to multiply terms. I prefer the ordinary appellations ead and {ail to the
more correct designations, carapace and post-abdomen. The azis is a convenient and well
understood term for the middle portion, and is better than fergum; and the terms side-
lobes, limb, or lateral portions of the tail; free and fixed cheeks, &c. to the head, are suffi-
ciently intelligible and well known to render it unnecessary to give the more technical
designations “‘ epimera,” &§c., even if we were quite sure of the correctness of all of these.
It is indeed quite possible that the free cheeks, with the connecting portion in front,
constitute the first or ocular ring, and the rostral shield would form the sternal portion of
the same ring. But there is not absolute certainty of this, and some naturalists disbelieve
it. The rostral shield may be the only representative of asmall anterior ring, and in that case
we should be only inventing prematurely a new term, in deciding to call the first segment,
as McCoy has done, the ocular ring. Nor would it be so convenient in description.
Again, the glabella certainly covers the region of the stomach, and the glabella-furrows
doubtless mark the attachment of the muscles of the several segments proper to the head, and
covered by the expanded carapace. There are always three (and in Ogygia and some other
genera, four) of these lateral furrows ; and if they indicate the number of segments combined
in the carapace, instead of the number of thorax-segments covered by it, we should still be
at a loss whether to call the neck-segment, which is always combined with the carapace,
the fifth or sixth segment in the general plan. But by adhering to the terms ‘“‘ free cheeks,”’
“facial” and “rostral sutures,” “rostral shield,” “glabella-furrows,” “neck-segment,” “ tail,”
&c., while there is no false assumption in the terms, so neither are they too far removed
from a scientific and technical nomenclature to be useful.
It may before long be practicable to adopt a more complete terminology. But in
these descriptions I adhere to Dalman’s formula, modernized a little to adapt it to our
more advanced knowledge of the group.

Famity—PHACOPID/. Zmmerich, Corda, Salter, Sc.

Hyes largely facetted, the cornea convex over each facet, forming a granulated, not a
smooth eye. Facial suture ending posteriorly onthe outer margin of the cheek. ‘Thorax
with eleven rings. Includes at present only one genus, Puacors. (Sub-genera.—T r1-
MEROCEPHALUS, Puacops, Acasrz, Cuasmops, OponrocuIiLe or DaALMANIA, CRYPH@Us.)

PHACOPID. 13

Beginning, then, with the family of the Phacopide, as being on the whole the most
typical and highly organized, I may remark that there is less difference between the various
groups into which this natural family is divisible than between the various members of the
neighbouring families. So much is this the case, that palaontologists have as yet
been generally unwilling to break up this group into genera, or to consider its divisions as
more than sub-genera of the great genus Phacops. Or, if they divided it, they have been
obliged to include a greater variety of forms in some of the divisions than in others.
Dalmania, or Dalmanites, is an example of this. It was intended by its author,
Emmerich, to include only the broad expanded forms of the genus; but M. Barrande, whose
authority has much weight, has widened its meaning so as to include all the forms which
have distinct lobes to the glabella; thus including in Dalmanites both convex and flat
forms, in fact, four-fifths of all the species; while the original term, P/acops, includes
the rest.

Prof. Goldfuss had previously taken the same view, but applied the term Acaste to the
larger group, leaving only the species with inflated lobeless glabella in Phacops. This
view is a consistent one, for Dr. Emmerich, in founding his genus, gave these last as the
type of it. But in the ‘ Neues Jahrbuch’ for 1845, Dr. Emmerich objected to this plan,
preferring to unite all the more compact and convex forms in Piacops, whether with lobed
or lobeless glabella, separating only the more expanded forms, as Da/mania, a term
which, though in general use, had unfortunately been in previous employ for a group of
msects. Prof. Burmeister did not attempt to divide the group at all, and Prof. McCoy
included all under Pdacops, while he recognized truly most of the subgeneric groups.

It will be seen that there is a considerable diversity of opinion as to the value of the
subdivisions ; and this arises, I think, from the fact before noticed, that the various sub-
genera in this, the highest group, differ only by characters of proportion and degree of
development of the different parts, while the main features of the group remain constant.

The great characters pointed out first by Quenstedt, viz., that the Phacopidee have eleven,
and only eleven, rings to the thorax, while other groups are variable in this respect, and
that all have the strongly facetted eyes, have in the eyes of naturalists overruled the
minor distinctions, and disposed them to undervalue the real differences of proportion
which exist. In the Decades of the Geological Survey, I have endeavoured to do justice
to all the above distinguished authors; and, retaining the name P/acops for the whole,
pointed out the several natural sub-genera. I believe still we shall best consult the con-
venience of students by retaining the common name.

No doubt, if we had the living animal, we should attach greater value to what in the
fossil appear subordinate characters. The degree of development of the eye, for instance,
should surely be a point of much importance in any group. ‘The expanded form and
large size of one division, contrasted with the contracted dimensions and compact habit of
another, is certainly of consequence, and may well afford generic characters.

And when we find the caudal margin in one form even and compact, while another has

14 TRILOBITES.

the component pleure free at their extremities, simulating the character of neighbouring
genera, we cannot doubt that we are looking at a group of genera combined by common
characters into a natural family.

If I express my own opinion, that the sub-generic groups here given are natural genera
in the ordinary sense of the word, and will be hereafter used as such—while for convenience
sake, and till the sub-divisions are completely established, we adopt the common term, it
will perhaps be all that in the present state of our knowledge is advisable.

Genus—Puacors, Hmmerich. Characters those of the family.

Range. Lowest Silurian—to Uppermost Devonian.

Subgenus I. 'l!Rrmerocernatus, AZ‘Coy, ‘ Annals Nat. Hist.,’ 2nd series, vol. iv, 1849.

Form compact, glabella inflated and expanded in front ; the
lobes, except the basal ones, obscure. Eyes small, of few large
lenses (often ost by abrasion). Head-angles not spinous.
Pleuree all rounded. ‘Tail small, of few seginents, with even
border, and not at all produced. Ex. P. /evis, P. Volborthi,
P. (Trimeroc.) Volborthi, P micromma, &e.

Barr., Wenlock rocks of E ;
Bohemia. Range. Upper Silurian—to Upper Devonian.

Subgenus II. Puacors, Hmmerich, 1845.

Form compact, glabella inflated and expanded in front, the two front pairs of furrows
obscure. yes large and well developed, of numerous lenses. Head-angles not spinous.
Pleure all rounded. Tail moderate, of few (often coalesced) segments, with an even
border, never produced.

Range. Upper Silurian—to Uppermost Devonian.

Subgenus III, Acastz, Goldfuss, 1845.

Form compact, or at least not expanded. Glabella not inflated, nor much expanded
in front ; all the furrows distinct. Eyes well developed, of numerous lenses. Head-angles

TRILOBITES. id

spinous. Pleure rounded or truncate, not produced into spines. Tail moderate, of less
than eleven segments, with an even border, but often mucronate.
ange. Lower and Upper Silurian.

Subgenus IV. Cuasmops, McCoy, 1849.

Form rather large and depressed. Glabella greatly expanded in front, the lobes
unequal, the hinder ones being contracted, and almost obsolete; the front pair greatly
expanded, and overlapping the others. Head-angles spinous. Pleura truncate. Tail
large, of few or many segments, not dentate, and seldom mucronate.

Subgenus V. Opvonrocuiix, Corda, 1847. (Daumania, Bmmerich, 1845.)

Form large, depressed. Glabella depressed, not much expanded in front; all the
lobes distinct, the front ones not enlarged at the expense of the others. Head-angles
long-spined. Pleuree truncate, and the hinder ones often produced. ‘T'ail large, of more
than eleven segments, with an even border,—often mucronate.

Range.—Lower Silurian, rare; Upper Silurian, common.

Subgenus VI. Crypuaus, Green, 1837.

Form of moderate size, depressed. Glabella depressed, not much expanded in front ;
all the lobes distinct, the front ones not greatly enlarged. Head-angles long-spined.
Pleurze truncate, and the hinder ones often produced, into spines. ‘Tail large, of many
segments ; the margin spinose.

I believe there are more subgenera of Phacops to be discovered and described yet. For
instance, there is probably more than one included here under 7rimerocephalus, and there
is a South African form of Crypheus, which has the characters of Acasfe in the compact
habit and convex tail. All the other subgenera also contain species which it would be
difficult to assign rightly to one or the other.

It will be observed that we have here a wide range of characters, and in regular
gradation, from the most expanded, flattened forms, with glabella deeply lobed, and the
segments of the large tail almost free, to the most compact and rounded form, with the
caudal extremity reduced in size, of even contour, and with the segments most coalesced.
‘We begin with the subgenus Trimerocephalus.

16 TRIMEROCEPHALUS.

Subgenus—TRIMEROCEPHALUS, as above.
1. Puacops (TRIMEROCEPHALUS) LZVIS, Minst., sp. Pl. I, figs. 5, 6, 7.

ASAPHUS or TRINUCLEUS, Sow. Geol. Trans., 2nd series, vol. v, pl. 57, fig. 30, 1840.

TRINUCLEUS L&VIS, Minster. Beitrage, Heft 5, t. x, fig. 6, 1842.

CALYMENE LEVIS, Phillips. Paleozoic Fossils, pl. 55, fig. 250 (1841).

TRIMEROCEPHALUS L&VIS, M‘Coy. Ann. Nat. Hist., vol. iv, p. 404, woodcut, 1849.
as — Ibid. Synopsis Woodw. Mus., 1851, p. 178.

Diagnosis.—P. (Trim.) late ovatus, levis, glabellé latissimd, brevi, genas subsphericas
trigonas impendente, lobis basalibus minutis distinctis. Axis thoracis angustus, fulcro
pleurarum axin approximato, sulcoque brevi. Cauda latissima brevis, axi longo 5-annulato,
lateribus 4-sulcosis, margine nullo.

This was first figured in England from very imperfect specimens, which came from
the only English locality yet known, viz., the Knowl Hill, near Newton Bushel. They
are mostly distorted, and, as first noticed by Mr. Pengelly, the head is usually disjoined
from the body and inverted, as if the animal had habitually kept it bent under, and been
preserved in the slate in that position. In that condition it is often difficult to dis-
tinguish the parts correctly.

But the number of specimens already collected enable us to restore the animal pretty
completely ; and there is not much doubt that it is identified rightly with the Zrinucleus
levis of Minster.‘ Both Mr. Sowerby and Professor M‘Coy have recognized it for this
fossil, and Dr. Sandberger has quoted it as a synonym, only he mixes up two or three
other species with it,—among others the (Calymene) Phacops levis of Mister.

It is clear, however, that it is distinct from the small trilobite originally named Calymene
levis by Minster, and next described ; as the following description will show.

And should it prove that the fossil called Ca/. devis by Miinster is a real species, we
should have to find a new name for this. Dr. Sandberger wishes to connect it with the
Phacops cryptophthalmus of Emmerich, a fossil also occurring in the same Devonian
formation. But though much disposed to believe that our fossil has true but superficial
eyes, which are not easily preserved, I cannot think that this is a true identification. The
eye of P. cryptophthalmus is very much more distinct, and I have figured what I believe
to be that species, with the eye, a little further on. P. cryptophthalmus, too, is described
and figured by Dr. Sandberger as having a larger semicircular tail, while ours has a very
short one. I may now describe the Knowl Hill fossil.

1 From the red shales of Guttendorf. The head only is figured by Minster.

PHACOPS. 17

General form broad-oval, not very convex. Length occasionally 1# inch. Head
_ smooth, semicircular, deeply trilobed, the lateral angles rounded. Glabella very broad in
front, spherical-triangular, occupying much more than one third the width of the head ;
convex, but not gibbous, and overhanging the front; neck-furrow strong, basal lobe
distinct, and with two lateral tubercles, the rest of the lobes obsolete. Cheeks triangular,
evenly convex, with a narrow margin, which is strong at the rounded angles, and lost in
front of the glabella; the neck-furrow strong. (Eyes absent in our English specimens,
but probably present in perfect individuals.)

Thorax of eleven segments, with convex narrow axis and rounded pleure; the
segments of the axis tuberculate at the sides ; the pleuree not much bent back, rounded
at the end, the groove narrow and short, the fulcrum placed at less than half way out
from the axis; facet rather large. ‘Tail short, transverse, flattened, arched in front,
straighter behind, about as long as the axis of the thorax is broad, and more than twice as
wide as long, of few joints, the axis conical, and reaching nearly to the margin, blunt at
the tip, and with four or five rings. ‘The sides wide, with not above four furrows, which
do not reach the margin, and are faintly interlined with other furrows.

Localities —Urrrr Devonian. Know! Hill, Newton Bushell ; specimens figured from

Mr. Pengelly’s cabinet (figs. 5, 6), and Mr. Vicary’s (fig. 7). I distrust the other

South Devon localities given in the “ Pal. Foss.,” viz., Mudstone Bay and Durl-
stone. But it is probable the species occurs at Brushford, North Devon, as
quoted by Professor Phillips.

P. cryPTOPHTHALMUS, Emmerich? PI. I, fig. 8.

PHACOPS CRYPTOPHTHALMUS, Emmr.,in Leonhard und Bronn’s Jahrbuch., 1845, pp.
27, 40, &c.
-—~ — Roemer. Paleeontographica, vol. iii, pl. vi, p. 14 (bad
figure), 1854.
— —_— Sandberger. Verst. Rheinisch. Schicht. Syst., t. i, fig. 6
(exclude his synonyms, as he includes several species,
among others, the P. /evis figured above), 1850.
Puacops timpatus, Richter ? (fide Sandberger).

<< P. capite semiorbiculari, lateribus frontis rectilineis, ad angulum acutum convergentibus.
Annulus fere rectilineus. Oculi parum evexi. Thorax latus. Pygidium breve obrotun-
datum, ew articulis 8, pseudopleuris 5, compositum. Superficies subtilissimé granulata.”
Sandberger.

I suppose this to be the species given in Sandberger’s beautiful plates. ‘The character,
“eyes but little prominent,” well agrees with this species. He figures the eyes as lunate,
and with fewer lenses than our Newton specimen. But the shape of the glabella is the
same, and I do not see that there is much room for doubt.

Locality —Urrer Devonian: Newton Bushell (Mus, P. Geology).

3

18 DEVONIAN TRILOBITES.

Subgenus—Puacors, as above.

2. P. (PHAcops) GranuLatus, Minster. PI. I, figs. 1—4.

CALYMENE, sp., Sow. Geol. Trans., 2nd series, vol. v, pl. 54, figs. 28, 24, 1840.
— GRANULATA, Minst. Beitr., Heft 5, t. v, fig. 3, 1842.

— LEVIS, Id. Ib., t. v, fig. 4.
— GRANULATA, Phillips. Pal. Foss., fig. 248 (exclude figs. m, n, 0, p), 1841.
PorTLOCKIA GRANULATA, M‘Coy. Synopsis Woodw. Foss., p. 177, 1851.

Not an inch long. General form broad-oval. Head semicircular, very convex,
covered with granules, the sides much bent downward. Glabella fully half the width of
the head, very tumid, slightly pointed in front and overhanging the front margin. Its
greatest width exceeds its length, even including the neck-segment. Sides converging at
an angle of 90°, the base narrow; a small basal lobe, with a tubercle on each side, but
no trace of upper furrows. Cheeks moderate, with a strong border. Eyes large,
prominent, with few, about thirty-six lenses, five in a row. (M‘Coy.)

Thorax ?>—

Tail semicircular, small, convex, with a smooth, declining, distinct margin, and
prominent conical axis, reaching rather more than two thirds down, tapering and almost
pointed at the extreme end, which fades into the limb, marked with six or seven rings,
obscure at the tip. The lateral lobes have five or six strongly duplicate furrows.

There seems no good reason for separating Miinster’s C. /evis from the above. It is
merely a decorticated specimen, the surface-granulation consequently absent. ‘The tail,
as figured by Miinster, has too many ribs, and too long an axis, but is otherwise like
ours; and Miinster’s figures are not fully to be trusted.

Locality—Urrrr Devonian. Petherwin, Cornwall. (Our best specimen, fig. 1, is

from Mr. Pengelly’s cabinet ; the others from the Mus. P. Geology.)

P. (PHacops) tatirrons, Bronn. PI. I, figs. 9—16.

CALYMENE LATIFRONS, and C. ScuLtotHetmit, Bronn., in Leonhard’s Zeitschr. f. d.
Miner., 317, t. ii, figs. 1—8, 1825.
CALYMENE LATIFRONS, Bronn. Lethea. Geogn., t. ix, fig. 4, 1835.
— TuBERCULATA, Murch. Sil. Syst., pl. xiv, fig. 4, 1837.
— Larreriiu, Steininger. Mémoires Soc. Géol. France, vol. i, pl. ii, 1834.
— Scutornemu, C. Bronentartit. Ibid., p. 350, 351.
— Larrerui, Phillips. Pal. Foss., fig. 249, 1841.
— ACCIPITRINA. Ibid., p. 128.
PorTLocKIA LaTIFROoNS, M‘Coy. Synops. Woodw. Mus., 1851, p. 177.
Puacors LATIFRONS, Sandberger. Verstein. Rheinisch. Schichten-Syst. Nassau, t. i,
fig. 7, 1850.
= -_- Roemer. Palseontographica, vol. iii, t. ix, figs. 24, 25, 1854-1855.

PHACOPS. 19

General form.—A large species; foreign specimens often attaining a length of 24
inches, and some of our English fragments indicate a still larger size.

The head occupies fully one third of the whole length, and is rather more than a
semicircle, and very convex. ‘The inflated glabella occupies more than half the width,
taking its measure at the wide front, from which the straight sides converge at an angle
of 85°. It is about as wide as its whole length, including the neck-lobe. The glabella
is very much rounded in front, and scarcely overhangs the narrow linear margin. _ Its
whole surface is covered with large, coarse tubercles, at equal distances, scarcely more
than their diameter apart. There are but slight traces of the upper furrows; but the
tumid glabella is strongly separated from and overhangs the linear basal lobe, which has
not distinct lateral tubercles, but in the internal cast shows deep pits on either side,
above and below the lobe. The neck-segment is strong and broad, wider than the basal
lobe. ‘The neck-furrow is continued round the smooth cheek, and separates a broad,
strong margin, leaving a subtrigonal space, much of it occupied by the great eye, which
varies from half to more than half the length of the cheek, and is placed rather behind the
middle of it. ‘The eye, from the depression of the upper eye-lobe, is subhemispheric, not
greatly curved, but strongly convex exteriorly, and covered by about fifty-four strong,
prominent large lenses,—in rows shortening towards either side; about five in one of the
central vertical rows. lxternally the lenses are very convex.

Foreign specimens show us that the cornea of this species is very thick, and rises into ridges
between the lenses; and it apparently thickens by age internally. At least old specimens (fig. 9) have the
substance much thicker, as shown by the great projection of the casts of the supporting cups (fig. 12*),
which of course are the spaces occupied by the soft substance which lay underneath the lenses.

In some instances, probably in younger individuals, the projection of the cups is considerably less
(fig. 13). In others again, the cups project so little, and the cornea is so thin, that there is little difference
of level between the ridges and the cups (fig. 1l@). Ido not think these differences of proportion, nor even the
varying numbers of the lenses in different individuals, at all tend to constitute distinct species. Steininger
gives us 46 to 50 lenses in one variety, 87 in another, and 130 (probably for the two eyes) in a third.
But he has not pointed out any clear distinctions in the species to accompany these differences in the eye.
A specimen of C. bufo, Green, which is a closely allied form, and may possibly be only an extreme variety
of our species, has 66 lenses in each eye.

The eye is elevated, the lentiferous surface not sunk in a furrow, but standing
prominently out from the cheek, and overhanging its own base (fig. 11). Head-angles
rounded. Obscure traces of the facial suture occur below the eye, but practically they
are soldered, and the head does not part at the sutures at all.

Thorax (in German and Spanish specimens) with the pleuree much bent down, so

* These cups in the cast of a Trilobite’s eye occupy the place of the vitreous body, according to Dr.
Burmeister’s explanation of the eye-structure. ‘ Organiz. of Trilobites,’ Ray Soc. edit., pl. vi, fig. 4d.

20 DEVONIAN TRILOBITES.

that the axis looks nearly as wide as the pleure. It is not in reality nearly so broad.
The surface is coarsely granulated, as is that of the tail, when the crust is preserved.

There is a perfect body, with eleven rings, in Mr. Vicary’s cabinet, of which a
woodcut is here given. The axis is convex, semi-cylindric, tuber-
cular, very slightly nodular on the sides, and little more than half
as broad as the pleura. ‘These are very convex, and as steeply
bent down as in Calymene; the fulcrum is placed at about one
third out, and as far from the axis in the hinder as the front rings.
The pleural groove is not very deep, and does not reach the long
facets. The ends of the pleurz are recurved and rounded.

Tail in our specimens (figs. 14, 15,) wide, more than semicir-
cular, arched in front, and very convex, with the axis quite elevated,
and separated by broad furrows from the convex limb. A few
Body and tail of Phacops lati- tubercles show on the ribs of the axis. It projects in front,

frons ; Newton Bushell. D :
slowly tapers to a rounded end at one sixth from the margin,
and is strongly annulated by seven or eight rings (ten in some German specimens)
while the convex sides slope quickly down, and have five or six strong ribs, straight, or
but little curved, and all but reaching the indistinct margin. There is no flat border.
The axis varies in breadth, but is never so much as one third the whole width, usually
one fourth. Incurved under margin very convex.

Localities.—LoweEr Drvontan. Hope and Barton, South Devon; near Liskeard and
Totnes, in slates with Plewrodictyum problematicum. Urrrr Drvontan (Pether-
win Group)? Newton Bushell. Uprrrmosr Dxrvonran (Barnstaple Group).
Croyde, Barnstaple, and the neighbourhood; Brushford, Pilton, &c., abundant ;
Yealm Bridge, north of Launceston (Pattison and Salter).

Foreign localities —Rhenish Prussia, Belgium, France, Russia, (P. 4ufo takes its place
in North America) ; also the Andes, South America (Mus. Geol. Soc.).

Var ll, fies UG,

I figure as a variety the wide pygidium found at Newton Bushell, which differs from
the ordinary forms of P. /atifrons, by the narrower proportion of its more depressed axis
to the sides, —little more than one fourth, and in having the six side ribs more direct than

usual. It can only be a variety, but the aspect is different to that of the common form.
Locality—Urrer Devontan.* Newton Bushell.

* | eee the upper quarries of Newton Bushell as the equivalent of the Petherwin beds. This
subject requires minute examination, and will be determined chiefly by the labours of local geologists.

The upper limestones are clearly not of the same age as the great Plymouth limestone, but nevertheless,
they contain a good many of its fossils.

PHACOPS. 21

P. (PHacors) Stokes, Milue-EHdw. PI. Il, fig. 1—6.

ASAPHUS MACROPHTHALMUS, Brongniart. Crustacés Fossiles, pl. i, fig. 5 (not fig. 4),
1822.
CaLYMENE MACROPHTHALMA, Buckland. Bridgw. Treatise, pl. lxiv, fig. 4 (mot fig. 5),
1836. Murchison, Silur. System, pl. xiv, fig. 2, 1837.
—_ Stoxest1, Milne-Edwards. Crustacés, 3, 324, 1840.
PorTLOCKIA SUBL&VIS, M‘Coy. Sil. Foss. Ireland, pl. iv, fig. 13, 1846.
Puacors Sroxesit, Salter. Memoirs Geol. Survey, vol. ii, pt. 1, pl. 5, fig. 1, 1848.
Quart. Geol. Journal, vol. vii, pl. ix, fig. 2, 1850.
—_ — M‘Coy. Synopsis Woodw. Mus., p. 163, 1851.
_ — Salter. Siluria, 2nd edit., pl. 18, fig. 6, 1859.

P. (Phacops) 1\—2 uncias longus, ovatus, granulatus. Glabella parum inflata, frontem
impendens, spherico-trigona, lobis basalibus rotundatis, reliquis omnino (etiam intis)
obscuris. Oculi magni, insuper depressi. Thorax axe angusto. Cauda brevis semicircularis,
convewiuscula, immarginata, avi depresso 5-annulato, lateribus 4—5-sulcatis, sulcis abbrevi-
atis obscuris.

This is a very common Upper and Middle Silurian fossil, but is never found in Lower
Silurian Rocks. Yet it is but imperfectly known, being generally in fragments. And it
has been moreover a troublesome one to the paleontologist, owing to the original mistake
of Brongniart, in confounding it with the true macrophthalma. And, until lately, specimens
of the more common P. Musheni, our next figured species, were constantly mistaken for
it. I believe the above synonyms may all be trusted, and I do not cite the more doubtful
ones.

The species is rather a small one, seldom exceeding an inch or an inch and a half in
length, and is obtusely ovate and very convex. ‘The head occupies less than a third and
more than a fourth of the whole length, and is semicircular, and wider than the thorax ; the
glabella is an equilateral spherical triangle, overhanging the front and the eyes, and much
narrowed behind, where the basal lobes are distinct enough as small tubercles on each
side of a linear lobe. This is overhung by the inflated upper lobes, which are confluent,
and show only very obscure traces of any of the upper furrows, even on the inner cast,
where they are strongest. The median furrows are short and curved, the upper strongly
bent midway, as in many species of the subgenus Phacops. Surface of glabella covered
with a fine granulation.

The cheeks are triangular, with a strong, continuous, marginal furrow. The eyes large,
much depressed above, and with the lentiferous surface gently curved, of numerous
lenses, and so placed that the forward end nearly touches the glabella, while the base is
widely distant, and does not moreover reach the sharp neck-furrow.

The body has a convex axis, narrower than the pleura, which havea deep sharp groove
for two thirds their length, and are steeply curved down beyond the fulcrum, the latter
being placed less than half-way out in the front rings, and at one third behind.

22 SILURIAN TRILOBITES.

The tail is semicircular, gently convex, but with the axis depressed and flattened ;
it tapers slowly, has a blunt apex, and is marked by five or six segments. The side-lobes
have four or five abbreviated narrow furrows; the upper ones are interlined, but all are
imconspicuous.

Our larger figure (fig. 6) is from a doubtful locality in the Wenlock Rocks, but is
certainly British. It shows the internal cast of the head sufficiently well. The species
grows occasionally to a rather large size, as may be seen by this specimen, and others
in the cabinet of Mr. Hollier, of Dudley. But usually the specimens are not larger than
our other figures. P. sublevis of M‘Coy is a very obscure drawing, but the original
specimens do not differ from P. Stokesiz.

Localities and Geol. Range —Luanvovery Rock, Galway ; Ayrshire ; Haverfordwest,
Pembrokeshire. May Hizu Sanpsronz, of Tortworth; May Hill ; Malvern ; Shropshire.
Wentock Rocks; Abberley; Malvern; Dudley ; Wallsall; North and South Wales;
Dingle, West of Ireland; Peebleshire. Lupnow Rocks; near Leintwardine, Shrop-
shire ; Pentland Hills, Edinburgh.

P. (PHacops) Nupus, n. sp. PI. VI, figs. 19, 20.

P. parvus, conveaus, omnino P. Stokesit simillimus, nist genis profunde marginatis,
oculorum lentibus paucis, caudd rotundiore, lateribus inflatis, costis distinctioribus.

It is difficult to define the fragments of this speeies, otherwise than by comparing the
parts with the better known and more perfect P. Sokesii, from which the species, a really
distinct one, differs in the following characters—the general form and the shape of the
glabella being extremely like in both cases.

The cheeks are larger, more rounded, and less convex, rather suddenly raised, and
with a tumid space between them and the glabella (¢). The lenses are far less numerous,
and have granules in the interspaces (/). The tail (fig. 20) is more oblong than a true
semicircle, transverse, blunt, and is more depressed. ‘The axis is short, with an obtuse
flattened tip, and has six rings; the lateral lobes tumid, with four arched furrows
(including the uppermost one), and a very obscure fifth furrow. ‘They do not nearly
reach the margin, and are faintly interlined. ‘The tumid sides, being rather strongly
divided from the flattened axis, give a peculiar character to the tail, very different from
that of P. Stokesii.

This new form has unexpectedly turned up in the collections made by the Irish
Survey in the wild district of the Dingle Peninsula. In the mountain of Cahirconree,
among slates of decidedly Upper Silurian date, occur some limestones, of whose age we
are not so clear, but containing the present species, which belongs to an Upper, and not a
Lower Silurian group. I have not much hesitation in referring them to the Wenlock, or

PHACOPS. 23

more probably the May Hill, formation. The //enus Barriensis, Spirifer plicatellus, and
other Upper Silurian species, occur with them.

Locality.— Wunutocx or May Hruu group. Cahirconree Mountain, west side, Dingle.
[Mus. Irish Industry, B. 242, 243.]

P. (PHacops) Musueni, n. sp. PI. II, figs. 7—12.

P. parvulus, vie %-uncie longus, ovatus, levis. Glabella oblonga, haud inflata,
superne urceolata, postice contracta, lobis basalibus profunde scriptis bituberculatis, reliquis
connatis lineisque angustis modo sejunctis ; sulci mediant breves, curvi ; superiores fracti.
Lobus frontalis transversus oblongus. Thorax axe convexo ut pleuris lato, his lenté recurvis
fulcro prope axin posito, sulcoque pleurali angusto distincto brevi. Cauda semiovalis
convera immarginata, ave prominulo distincto pauci-annulato, lateribus 3—4A-sulcatis
abbreviatis angustiori.

A much smaller species than the true P. Sfosesz?, with which it has been very generally
confounded. Nevertheless it differs by several important particulars, the chief of which is
that the shape of the head is long instead of broad, and the glabella decidedly oblong
instead of broad-triangular. The other portions, body and tail,—also differ; the axis
of the body is broader, and that of the tail much more prominent, while the tail itself is of
a longer shape, less transverse.

The length is seldom more than three fourths of an inch. The head in good specimens
is half a broad oval (that of P. Stokesiz being a semicircle). The glabella is much
more than one third the whole width, oblong, only rather broader above than at the eyes,
and is urceolate, the sides bulging out between the eyes, and then contracted for the
hinder portion. The glabella is not at all inflated, nor does the front overhang in any
sense, and the facial suture is not even quite marginal in front.

The eyes are fully half the length of the glabella, and very large and convex, not
depressed above, about as deep as they are broad, and containing nearly 130 lenses. ‘These
have no visible spaces between them. The eyes are not very prominent, and on a
side-view appear sunk, especially towards the front, to the cheek. They vary a little
in size and prominence, but not very much so.

The body has.a rather convex axis, which is as broad as the sides, or nearly so. The
pleuree are curved down gently at the fulcrum, which is at about one third anteriorly and
less behind. ‘The pleural groove is narrow, and reaches but little more than half-way along
the pleuree.

‘The tail is longer than semicircular, very convex, smooth, with a prominent axis (not
flattened as in P. Sfokesiz), and reaching fully four fifths the length. It is long, conical,
ringed above, and smooth towards the bluntish point ; the sides are smooth, the three or four
faint lateral furrows not reaching half-way over the convex limb, even in the upper portion,

24 SILURIAN TRILOBITES.

and being quite obsolete in the lower. Only the upper ones are interlined. There is no
marginal flattened space, nor any concavity ; the tail is gently convex to the very edge.

Locality. Wenlock Shale and Limestone.—Malvern, abundant in Wenlock Shale ;
Dudiey. It has not yet been found in other localities.

Subgenus—Acaste.

Puacops (Acaste) Downine1a, Murch. PI. I, figs. 17—36.

CALYMENE MACROFHTHALMA, Brongniart. Crust. Foss., pl. i, fig. 4 (no fig. 5), 1822.
~ —_ Buckland. Bridgwater Treatise, pl. Ixiv, fig. 5 (not fig.
4), 1836.
— Downinera, Murchison. Silurian System, pl. xiv, fig. 3, 1837.
= — Milne-Edwards. Crust., iii, 324, 1840.
ASAPHUS SUBCAUDATUS and A. Cawport, Murchison. Sil. System, pl. vii, figs. 9, 10.
AcasTE Downinera&, Goldfuss. Syst. Uebersicht der Trilob., Neues Jahrb., 563, 1843.
PHACOPS MACROPHTHALMA, Burmeister. Organiz. der Trilob., 139, 140, 1843, ed. 2
(Ray Society), 1846, p. 92.
— Downineim, Emmerich. Neues Jahrb., 1845, p. 40, pl. i, fig. 2 (icon mala).
— — Translated in Taylor’s Scientific Memoirs, 1845, vol. iv, pl. iv,
fig. 2.
— — Salter. Memoirs Geol. Survey, June, 1848, vol. ii, pt.i, p. 336,
pl. v, figs. 2—4 ; ‘Decade vii (1853), pl. i.
oo — M‘Coy. Synopsis Pal. Foss. Woodw. Mus., 160, 1851.
— — Murchison. Siluria, 2nd edit., pl. 18, figs. 2—5, 1859.

P. viv biuncialis, alutaceus, margini frontali capitis angulato. Gilabella depressa sub-
parallela, sulcis utrinque tribus distinctis, lobo basali lineari, secundo ovali, superior: trans-
verso, sulco antico ascendente sinuato ; lobis omnibus planis, fere ad medium glabelle, spatio
angusto interjecto, extensis ; cervice elevato. Oculi modict. Cauda subtrigona, marginata,
apice angulato ; axi convexo costato, costis 5 distinctis predito ; lateribus 5-costatis, costis
duplicatis.

If I have given a lengthy set of synonyms, they do not represent a moiety of the works
in which this very common fossil is noticed. It is one of the really abundant Upper
Silurian species, being moreover one of the few trilobites which are common in the Ludlow
rocks, as well as in Wenlock strata. No trilobite is more frequent on the Dudley slabs ;
but it is rare to find it in the underlying shale. I have seen it from many parts of Britain,
but do not know that it has ever been described from foreign localities ; nevertheless it
does occur in the true Upper Ludlow rocks of Nova Scotia, as we learn from the collec-
tions brought to the International Exhibition by the Rev. D. Honeyman, in 1862.

An inch and a half long ; general form long, ovate, broader in front, the axis following
the same lines, and regularly tapering towards the tail. The surface is moderately convex,

PHACOPS. 25

the axis raised above the sides, not separated by deep furrows except in the head, and
more convex in the thorax than in the head or tail.

The head is less than a semicircle, though just twice as long as broad; the general
outline rather triangular, from an indentation in the outer margin on each side of the
glabella; the front is not produced, but angular. The glabella occupies more than one
third the width of the head in front. It has nearly straight, parallel sides, and rises con-
siderably above the cheeks, but is depressed rather than convex, especially the forehead-
lobe, which slopes gradually to the narrow marginate front. Neck-lobe strong, broader than
the first basal lobes, which are transverse and linear; the middle pair are broader than
these, and oval. The lower furrow bends downwards, and reaches the side of the glabella ;
the middle one is abbreviated, and curves the reverse way. Upper lateral lobe transverse,
scarcely triangular, bounded above by a sigmoid furrow, which runs obliquely out above
the eye.

All the furrows stretch equally towards the middle of the glabella, leaving but a
narrow space between their ends; between the upper pair a short longitudinal depression
occurs. ‘The lobes are not swelled between the furrows, but the surface is even, and the
furrows shallow (they are, however, sharply defined on the internal cast), the neck and
basal furrows strong ; the upper ones fainter.

The cheeks are steeply bent down, their outer margin not distinguished by any furrow,
and they slope gradually from the eye, without any ridge or groove, beneath the latter ;
the neck-furrow is continued almost to the angle, which is rounded off, and has a tubercle
only in place of a spine. ‘The facial suture cuts the outer margin in a curved line opposite
the base of the eve; on the under surface of the head the suture cuts the margin further
backward (fig. 4). In front of the eye it runs along the axal furrow and round the
glabella just outside the marginal furrow. It is thus what is called cz¢ramarginal.

Eyes moderately large, in some specimens (figs. 18, 25, 26, 30) much larger than others ;
and they rise occasionally to the level of the glabella, but are generally lower. The eye is
not very prominent ; it is placed half-way up the cheek, near to the upper glabella-lobes, and
occupying their length ; eye-lobe with a raised outer margin ; lentiferous surface broad,
with about 155 lenses in the eye, each vertical row containing eight. The cornea is convex
over the lenses, and the intermediate flattened spaces are finely granular, the granules
forming a rough hexagonal network toward the base of the eye; the lenses are nearly their
own diameter apart, but this varies much in different individuals, the space being often
much less. (Fig. 36, d, e.)

On the under side of the head the incurved front portion, or Aypostome, as in all the
genus, is continuous across ; it is broad (fig. 36, 4) and granular, like the upper surface. The
labrum is also granulate; it is subquadrate, broadest at base, regularly and strongly convex ;
a faint concentric furrow runs round its sides and tip, just indicating a narrow margin
more flattened than the other parts; there are no lateral furrows, but high up on each
side isa small tubercle. The tip is obtusely truncate, with no visible serratures. The

4 .

26 SILURIAN TRILOBITES.

labrum is narrower than the glabella, and half its length; but from the position of its base
its tip reaches back as far as the middle pair of glabella-furrows.

Thorax considerably longer than the head; the rings not very convex; the axis of
nearly equal breadth with the pleuree. ‘These are traversed by a straight deep groove
(fig. 36 g), curved rather abruptly down at the fulcrum, which anteriorly occurs at the
inner third of their length, and in the posterior ring does not reach further than one fourth.
The anterior edge of each pleura is sharpened or facetted to pass under the preceding one,
and the posterior edge is thick.

Each pleura is bent forward at its end, which is notched somewhat deeply, and on the
under side of each, in front of this notch, is placed a tubercle. When the animal was in
the act of rolling up, the tubercle served as a buttress to prevent the posterior ring from
being pushed too far forward ; the tail, too, has similar tubercles on its anterior edge.

The under side, cleared out with great labour and patience by Mr. John Gray, of
Hagley, shows two or three other interesting points distinctly.

First. The incurved under portion, which is very narrow in the tail, and not much
broader beneath the border of the head. But along the pleure a wider strip is turned
inwards, which is smooth in this genus, and has a straight inner edge; while it presents
on its forward margin the tubercle before mentioned.

The interior ridges of the axis show distinctly along the axal line as short, transverse
ridges, more prominent a good deal on their inner margin, which does not even show,
except as a slight depression, on the upper side. This broad ridge does not extend into
the tail portion.

Var. a, vouearis. PI. II, figs. 17—25.

Figs. 22, 24, show about the ordinary form of the species ; with broad glabella, complete
glabella-furrows, and pointed front. The tail-furrows are strong, and the apex pointed.
The axis of the body, too, is prominent.

Varieties.—¥ig. 24 shows some tendency in the narrower glabella towards the variety
constrictus, figured in the upper part of the plate. It has, however, very iarge eyes, like
the var. macrops, but the tail wants the lateral furrows, or rather has them much slighter
than usual, and the apex less pointed. The body-axis is narrow and prominent.

Fig. 23, a very large individual, is more convex than usual, and the eyes are depressed
so as not to rise nearly to the level of the glabella. The tail is of the ordinary type.

Var. 8, Macrors. PI. II, figs. 26—29.

The variety macrops is distinguished by the very large prominent eyes :—they occupy
a large part of the cheek. I counted in one of them 140 lenses. ‘The interspaces are
granulated. Fig. 28, which belongs to this marked variety, has a larger head than usual,

PHACOPS. 27

and the tail has the side-furrows more than usually obsolete. Mr. Ketley’s specimen,
(fig. 27) has the front glabella-furrows strong, and the pleurz flattened. The tail is of
the usual type, but the side-furrows are obscured.

Var. y, inruatus. PI. II, figs. 30, 31 (82, 33 ?).

Fig. 30 shows a remarkable variety. While it retains most of the characters of the
ordinary form, it nevertheless puts on a very different aspect. The glabella is greatly
swollen, so as to be very convex, instead of flattened, in front, All the furrows are indeed
distinct and in their proper situations, but from the inflation of the glabella they appear
crowded. ‘The eyes are small. Dr. Grindrod’s cabinet and the Museum of Practical
Geology are the only collections which I know to contain this variety. Probably fig. 31,
a Ledbury specimen, belongs to var. 8. It has the upper glabella-furrows all but obsolete.

On the other hand, figs. 32, 33, also from Ledbury, show all the furrows of the head
and tail stronger than usual. ‘hese are casts of the interior, and the thickening of
all the internal ridges is a constant character in Trilobites.

Var. ? 8, sptnosus. Woodcut, fig. 7. Fie. 7.

Agrees with the ordinary variety a in the glabella, but has short LN S_
head-spines! Only a single specimen is known; it is in Mr. Edgell’s

collection. With it, however, occurs a pointed and strongly furrowed Phacops Downingie, var.
: : é : ahs 6, spinosus. Upper
tail, which may belong to it, and would mark it as a very distinct form; — Ludlow rock, Ludlow.

possibly a species.

But to pass on to a marked and definite variety, which has not yet received a
name, and which would by many be considered a distinct species. I propose, however,
only to term it—

Variety or Sub-species' &, CONSTRICTUS.
Puacops consrrictus. PI. I, figs. 13—16.

Minor, fronte convexiort rotundato haud angulato, oculis magnitudine variis, prope
glabellam positis, Cauda rotundata, sulcis obscuris.

1 Tam much disposed to follow the plan adopted by some eminent botanists, and to make a distinction
between the occasional variations in form and structure which are usually termed varieties, and those
more permanent and well-defined groups, which are designated swb-species. Regarding these latter, there
will always be differences of opinion as to whether they should receive separate specific names, and it seems
the most convenient plan to describe them as distinct forms, which may be considered either species or
varieties by the student, while their supposed relation to the parent species is indicated by their being
grouped under it. We do not yet know what the limits of species and varieties are, and probably there is
no real line to be drawn; but all truly distinct forms should receive attention, and, for the purpose of the
geologist especially, a marked variety is as useful as a species.

28 SILURIAN TRILOBITES.

This is smaller than the typical variety, seldom more than one inch long, and has a
different aspect, from the rounding of the front and the greater convexity of the forehead-
lobe. ‘he glabella has nearly parallel sides, as in the typical form; the front furrow is
not stronger than the rest, but is rather more sigmoid. The middle furrows reach the
side of the glabella; the neck-segment is prominent and has a distinct tubercle. The
eyes are small, with about 130 lenses, and placed very near the glabella.

The axis of the body is convex; the pleurz more tumid between the grooves than usual.
Some young specimens have larger eyes in proportion, and the front furrows obscure.

But these variations with larger or smaller eyes, more distinct or less dis- Fie. 8.
tinct glabella-furrows, &c., occurring as they do both in the angulated and
rounded varieties, oblige me to consider them as of the same species, though »
the characters above given show that we are dealing with a very distinct prc Mens
variety or swb-species. sepia sia

There is yet another variety, which might be called var. Z, cwneatus. Fig. 8. C™"*Y:

Localities and Geol. Range.—The ordinary variety a is found from the May Hill
Sandstone to Upper Ludlow Rock. May Hii Rocks; Pembrokeshire; Norbury and
Bogmine, Shropshire. Wootnope Limestonr and Wentock SHate; Malvern, many
localities ; Burrington, Shropshire ; Usk, Monmouthshire ; near Llanrwst, and many places
in the Denbighshire grits, N. Wales. Pembrokeshire and Carmarthenshire, S. Wales.
Wentocx Limestonz of Dudley, Wallsall; Benthall Edge; Malvern; Abberley, &c.
Lupiow Rocks, Lowrr anp Upper; Shropshire ; Carmarthenshire ; Pembrokeshire.

The varieties 6, y, above described, are as yet only known from the Wenlock Rocks ;
variety y only from the Wren’s Nest and Malvern; but the variety 8 is from Upprr
Luptow strata, Whitcliff, Ludlow (Mr. Edgell’s cabinet) ; and the species or variety ¢, con-
strictus, only from the Wenlock shale, of Dudley, Wallsall, and especially Malvern. Var. Z
is from the Denbighshire grits of Llanrwst, near Conway. (Woodw. Mus.)

Foreign distribution.—Nova Scotia, in Upper Ludlow rocks.

P. (Acastg) apicuLatus, Sa/ter. Pl. I, figs. 36—88.

PHacops aPICULATUS, Salter, in Prof. Sedgwick’s Synopsis Classific. Pal. Rocks,
fasc. 2, Appendix iii, pl. iG, figs. 17—19 (1852).
PorTLOcKIA aprcuLatTa, M‘Coy. Ibid. (1851), fase. 1, 162.
PHacops apicuLatus, Salter. Memoirs Geol. Surv., Decade vii, art. 1, p. 9. (1853.)
— — id, Siluria, 2nd ed. (1859), p. 75, Foss. 13, f. 2.

P. (Acaste) omnino P. Downingiea simillimus, sed capite longiore. Glabella elongata
antice convexior, lobis basalibus circumscriptis subtrigonis nec transversis ; sulco mediano
longiore, supremo distincto. Oculi elongati depressi. Anguli capitis brevissime mucronati.
Cauda ad apicem compressa et in apiculum recurvum brevem producta, avi angusto.

Heads and caudal pieces of this small species are not uncommon in the Caradoc rocks

PHACOPS. 29

of Wales and Shropshire, but are rare in the Llandeilo flags. It is a smaller fossil than
P. Downingie, though much like it, and is readily distinguished by the faint upper lobes
of the glabella, and the strongly apiculate or shortly mucronate tail. The entire fossil
could not have been above one and a quarter inch long, and is rather depressed than
convex.

Head semicircular (smooth ?), the front bluntly angulated, or, rather, like a broad
Gothic arch. The glabella is long and parallel-sided, but slightly broader in front, and
occupies less than half the width of the head. There is scarcely any margin in front of
the forehead-lobe, the sides of which, above the eye, slope into the cheek without distinct
axal furrows at that point. These are indeed but faint throughout, but are nearly parallel
along the two upper lobes, and the basal lobes and neck-segment are scarcely narrower
than the upper lobes. The neck-segment is strong and prominent; the basal lobes are
transverse-oval, and deeply circumscribed, except on their inner margin. The uppermost
furrows straight, oblique, deepest just over the eye, and thence extended nearly to the
centre. ‘I'he middle furrow is very faint, and gently arched upward: it nearly meets the
margin, but is so faint that the two upper lobes appear like one.

The eye is small and conical, not much curved, and covers the space of the two upper
lobes, leaving a wide space between it and the sharp neck-furrow. There is no marginal
furrow to the cheeks on their outer sides, by which character it is easily distinguished
from the following species. There is a very short mucro to each of the head-angles.

‘The tail is broad-triangular, and strikingly recalls that of P. Downingie. The largest we
have is seven lines wide and five long, without the short recurved apiculus. The axis rather
narrow, not nearly equal to the limb, regularly conic, ribbed by eight or nine distinct
ridges, and the smooth terminal portion is pinched up, as it were, into the short apiculus.
The axal furrows are not strong; the sides are convex, declining, and with a broad concave
margin, not crossed by the side-furrows, which are five in number, and are deep narrow
grooves, interlined pretty strongly on the cast (fig. 37), but less distinctly on the outer
surface (fig. 38). Our figures do not express this as well as they ought to do.

Localities.—Urrer Luanpeino ruac. ‘Treiorwerth, near Llanerchymedd, Anglesea.
Carapoc Sanpsrong. Soudley, Horderly, and many other places in Shropshire ;
abundant ; Cerrig-y-Druidion ; Bala Lake; Llangollen; Meifod ; Conway River ; Pwllheli, .
&c., in North Wales; Coniston Water and Troutbeck, in Westmoreland.

Puacops (AcAsTE) Mims, n. sp. PL. I, fig. 35.

P. (Acaste) minor, capite elongato (angulis obtusis?). Glabella subparallela, haud
convexa, lobis superioribus obscuris, basali distincto. Oculi submediani, modict. Gene
lati-marginate, sulco antico exarato.

Though at first sight a good deal resembling P. apiculatus (p. 28), this little trilobite is

30 SILURIAN TRILOBITES.

found to differ when closely examined. Its glabella is much the same in shape, but rather
broader above; the basal lobes not so strongly marked, especially in the cast ; the upper
furrows less defined, and making a less indentation on the sides; the upper eye-lobe
broader and flatter. The cheeks, without being smaller, project less at the (blunt?)
angles and more at the sides, and the eye is a little further forward.

But the most striking character, although it seems to be an unimportant one, is the
very distinct marginal furrow which subtends the eye closely in front, and leaves a strong,
broad, anterior margin to the cheek. It does not, however, quite meet the neck-furrow,
which rises towards it and runs nearly to the angle.

This apparently neutral character is nearly the only one on which we can rely ; the
rest are proportional characters. But the species is a distinct one; and although it is
almost too imperfect to name, the little Lower Silurian oasis in Cornwall, from whence it
comes, is of so much geological interest, that I venture to distinguish it. As the fossils
of that area are wholly dissimilar from those of other portions of the British Silurian
rocks, and only comparable with those of the “ May” Sandstone of Normandy, it is
worth while to note the discrepancy by describing even the more obscure species.

Calymene Arago, De Verneuil, and Homalonotus Brongniartt, Deslongschamps, accom-
pany it, and will be described under their appropriate genera. The same set of fossils is
found in the remarkable pebble-bed at Budleigh Salterton, in South Devon. See descrip-
tion of the next species. ?;

There is a certain resemblance to Dalmanites Phillipsi, Barrande, and even to Daim.
Hawilei, Barr., from the Lower Silurian rocks of Bohemia. But P. mimus is sufficiently
distinct from all.

Localities.—LuaNDuito Fuacs ? of Great Peraver, near St. Austell ; in South Cornwall.

P. (AcasTE) 1ncertus, Deslongschamps. PI. I, figs. 27, 28.

ASAPHUS INCERTUS, Desiongsch. Trans. Soc. Linn. de Calvados, vol. ii, p. 298, &c.,
pl. xx, fig. 5, 1825.

PHacops (DALMANN1A) INcERTUS, Rowault. Bulletin Soc. Géol. Fr., vol. viii, p. 371,
1851.

P. (Acaste) converus, biuncialis, capite convero, fronte angulato, cauddé mucronata.
Glabella antrorsim parum dilatata, sulcis anticis haud profundis, posticis valde exaratis ;
mediano et postico arcuatis. Anguli genales brevispinosi. Cauda trigona lata; aai
9-annulato, convexo, in mucronem longum crassum recurvum producto ; lateribus 6-sulcatis,
sulcis interlineatis.

About two inches long. We have only head and tail, the former convex, with a
glabella wider than the cheeks, and subparallel, or rather with the sides gently divergent
in front (not abruptly, as in P. socialis ; the front is bluntly pointed, as in that species).

The glabella-furrows are well marked on the cast, and reach fully two thirds inwards,
towards the centre. ‘The upper ones are oblique and sinuous; the middle pair arched

PHACOPS. 31

forward. ‘The basal pair are by far the strongest, and enclose, in conjunction with the
interrupted neck-furrow, a pair of transverse, oblong, nearly circumscribed, and very
convex basal lobes, not so large as the middle pair. The contrast between the deep basal
furrows and the fainter upper ones is striking, and is expressed by Deslongschamps’
term “postice bituberculato.””*

The cheeks are regularly convex, the neck-furrow being strongly marked as far as the
angle, which seems to have been armed with shorter spines than in P. socdalis, Barrande
(Tril. de Bohéme,’ pl. 26), the species which is most nearly allied to ours. It is not,
however, quite certain there were even short spines to the head-angles.

The outer side of the cheek is moderately arched, and margined by a fainter furrow
than the neck-furrow, but continuous with it up to the angle of the head. The axal
furrows are not very strong; and there is no margin in front of the glabella.

The eyes are small, placed centrally on the cheek, not in advance of this position.
The facial suture beneath the eye is nearly direct to the outer margin, and vertical in front
of the eye.

We have not the body. ‘The tail also resembles that of P. socialis; but has a shorter
mucro and fewer ribs. The shape is broad-triangular, a good deal wider than long; the
axis narrow, conical, and rather convex, and at its apex curved upward and passing into a
strong, thick, and greatly recurved mucro, whose exact length we do not know, but which
was probably as long as the tail itself. There are six flat side-ribs, somewhat arched, and
directed obliquely backwards ; they nearly reach the very narrow, flat margin, and are
interlined throughout. The sides are tolerably flat, except towards the apex, where they
become tumid, and run into the broad base of the thick, recurved spine.

Comparing P. zxcertus with the very nearly allied P. socialis, we find the latter with a
far more triangular glabella, the furrows of which are more equal; with spinous head-
angles, forward eyes, several more rings upon the axis of the tail, which, besides, has more
side-ribs and a much more slender spine—the latter less recurved. But the two species
are nearly allied, and the group of trilobites, and shells also, which occur in the subjoined
locality, are identical with those of the Lower Silurian sandstone of Normandy, where
’ P. socialis also occurs, and some other Bohemian forms with them. The subject of the
geographical distribution of trilobites is worthy of a separate essay.

Locality. Lownr Siiurtan pebbles, in the “ Pebble-bed” of the New Red Sandstone,
Budleigh Salterton, South Devon (Mr. Vicary’s collection). Also in the ‘May Sand-
stone” of Jurques, Normandy (Eudes Deslongschamps).

1 Deslongschamps’- Latm description is short, and not very distinctive. ‘Clypeo triangulari, angulis
brevibus incurvatis...... fronte magno convexo, antice acuto, postice bituberculato; genis parvis, oculis
lateralibus” (p. 317).

32 SILURIAN TRILOBITES.

Puacops (Acastg) JAmxsit, Portlock. Pl. 1, figs. 39—41.

Puacors Jamusii, Portlock. Geol. Report of Tyrone and Londond., p. 283, pl. 3, fig. 10,
1843.
—_— — Salter. Decades Geol. Survey, No. 7, art. 1, p. 10, 1853.
— — — In Morris’s Catalogue, 2nd ed., p. 113, 1854, &c.

P. (Acaste) unciam latus; capite semicirculari, fronte subangulato marginato
crasso. Glabella fere plana tuberculata, antice latissima, postice ad dimidium contracta,
lateribus rectis : lobo frontali late trigono, oculos impendente ; ceteris radiantibus, supremo
maxino trigono, medio lineart obliquo haud abbreviato, basali transverso ; lobis omnibus fere
ad medium glabella, spatio angusto interjecto, conniventibus. Gene declive marginate,
angults obtusis. Oculi abbreviati valde curvi. Thorar? Cauda rotundata, quam longa
tertiam partem latior, depressa ; axt satis magno conico, marginem nullo modo attingente,
annulis 8—9 ; lateribus sulcatis, sulcis 6—1 equalibus, leviter per totum interlineatis.

I have seen but four or five specimens of this. But the species is not uncommon in
Waterford. It is a marked one, conspicuous for the flatness of the glabella, and the
thickened outer border. The cheeks are triangular; the eyes have a peculiar angular
upper lobe. The tail is a good deal like that of Ca/ymene, and the whole aspect is unusual
for Phacops. Portlock’s figure, which, like all the rest of his plates, were but second-
hand office copies of Mr. Dunoyer’s beautiful drawings,’ gives no proper idea of the
species, which is named in honour of Lieut.-col. James, of the Ordnance Survey.

P. Jamesii must have been nearly two inches long. It is very gently convex, the head
flattened above, the cheeks declining rather steeply. ‘The glabella, covered closely with
not very coarse tubercles, occupies much more than half the width of the head, especially
in front, where it is very broad, the sides converging behind at about 70°. The forehead-
lobe is abruptly wider than the rest, overhanging the eye. It is transverse, subangular
in front, with a thickened margin, and behind bounded by the nearly straight upper
furrows, which run far towards the middle, and are of equal strength throughout. The
other furrows radiate, the middle ones declining towards the base of the eye. The
basal ones more direct, nearly parallel to the neck-furrow. The axal furrows are very
faint.

The eye is small, strongly curved, set near the glabella, and on a level with it; the
upper eye-lobe is pointed, the lentiferous surface imbedded, as it were, in a fold of the
cheek, which is here convex, but declines all round, and slopes away to the margin. The
cheek itself is triangular, with obtuse outer angles, and is only granular, not tubercular,
strongly marginate on the outer side, and with a sharp neck-furrow, which does not meet
the marginal furrow.

Tail semicircular, one third wider than broad, depressed (this is not due to pressure).

‘The original plates were found to be rather too large, and unfortunately had to be cancelled.

PHACOPS. oe

Axis rather large, not equal to the limb, conical, rounded at the tip, and reaching less than
four fifths of the whole length; annulated throughout by about nine rings ; the sides with
seven furrows directed obliquely, and reaching nearly to the margin, interlined throughout.

‘The species is unlike any other, but has perhaps its nearest relations with P. alifrons,
next described. From that species the shape of the forehead-lobe will distinguish it,
while there is only some general resemblance in the shape of the flatter glabella, and
especially in the small, greatly curved eye.

Locality. Caravoc Rocks 6f Waterford; Tyrone. (Mus. Pract. Geology.)

Puacors (AcastE) aLirrons, Salter. Pl. I, fig. 31—34.

PHACOPS ALIFRONS, Salter, in Appendix to Sedgwick’s Synops. Woodw. Foss., fase. ii,
tab. 1 G, figs. 12—14, 1852.
— — Ibid. In Decade 7, Geol. Survey, Art. 1, p. 10, 1853 ; and Morris’s
Catal., 2nd ed., 1854.

P. (Acaste) capite tuberculato sesquiunciam lato, gibboso, anticé truncato, bis quan
longo latiort. Glabella elevata sed paullum convera, ad basin angustata, superne dilatata
obtusa truncata, lateribus subrectis; lobo frontali brevi transverso limbum crassum
wmpendente, uirdque angulis tumidis cum margine genarum confluentibus ; lobis lateralibus
tumidis, supremo subtrigono modico, reliquis fere rotundis abbreviatis ; genis declivibus
marginatis. Oculi curvati. Cauda semicircularis tumida, axi lato convero 8—9 annulato,
apice obtuso nec marginem attingente ; lateribus converis, costis T—S8 simplicibus ; margine
angusto.

We are compelled to be minute in the specific characters of these species of Phacops,
as they really differ but in proportional characters ; yet, if it were allowable to abbreviate,
it would certainly be excusable in this case, for in no other species which I know does the
outer and upper angle of the glabella run out distinctly into the margin as it does in this
fossil. But three or four heads of it are yet known, and two or three caudal shields
associated (not in actual contact).

The species was a tolerably large one, the head (in our largest specimens, copied from
the figure formerly given by myself in Professor Sedgwick’s work) is 1} inch broad.
‘he entire form may have been 8 inches long. ‘The lesser figure (fig. 33) represents a
somewhat smaller, but characteristic specimen. Both are from North Wales, and I do
not know it elsewhere.

‘The head is highly convex, and rather strongly truncated in front, but the glabella,
though tumid, is rather depressed on its upper surface. It is very wide in front, the
upper lobe overhanging the eye; and being connate with the thickened border of the
cheek, seems to be drawn out into it. The lateral Jobes are short, the upper largest, but
not greatly so, triangular; the upper furrow which bounds it running nearly straight
across (not upward, as in P. Jamesiz); the second, as deep, directed downward and out-

5

34 SILURIAN TRILOBITES.

wards; the rest are short and rounded, the base-lobes narrow, the neck-segment
prominent.

Cheeks very convex, separated by deep axal furrows from the glabella, strongly cir-
ccumscribed in front by the deep marginal furrow, and behind by the neck-furrow; the
angles rounded, not spinous? Eyes prominent, small, curved, somewhat sunk, overhung
by the angles of the glabella.

Of the tail we have but few specimens; our largest is that figured in Professor
Sedegwick’s work. It is semicircular and very convex with a broad, prominent axis
reaching nearly the whole length, and blunt at the apex; rmged throughout by eight or
nine ribs, and with no smooth terminal portion. The sides are also convex, with about
eight simple, radiating ribs, not much curved, and with no intermediate furrows. ‘The
ribs abut abruptly against a narrow but distinct margin. The other tail (fig. 34) is less
certainly of this species, but is found associated with it. It has a wider margin, and only
seven lateral furrows.

Localities. —Caravoc rocks, North Wales ; at Capel Garmon, near Llanrwst ; also at
Penmachno, and Pont-y-Glyn Diffwys, near Corwen; and near Llangynnog, in Mont-
gomeryshire. (Mus. Pract. Geol. and Woodw. Mus.)

Puacors (Acastr) Bronentarti, Portlock. PI. I, figs. 20—25.

¢ ? P. Bronentartt, Portlock. Geol. Report, pl. 2, fig. 8 (exclude the references), 1843.

P. Murcuisoni. Ibid., fig. 9.

Var. 9? P. Datmant. Ibid., fig. 7.

P. Bronentarti and P. Datmant, Salter, in Decade 7, Geol. Survey, Art. 1, p. 10,
1853 ; and in Morris’s Catalogue, second edition, pp. 112, 113,
1854.

3 P. biuncialis, elongatus, granulatus ; capite longo trigono, fronte angulato subrecurvo.
Glabella ad basin contracta, anticé valde dilatata nec convewa, lobis utrinque tribus radi-
antibus ; lobo antico maximo triangulalo, a frontali sulco valido—a medio sulco leviore—
sejuncto ; lobis infimis minutis hemisphericis circumscriptis sese remotis. Oculi maaimi, a
lobo frontali usque ad sulcum cervicalem tracti. Anguli genarum obtusi. Thorax lateribus
parallelis, axi convexo angustato, pleuris abruplé deflexis apicibusque rotundatis—fulcro
intra medium posito. Cauda trigona, aati longé conico angustissimo feré ad finem caude
eatenso, 10-annulato ; latertbus 5-costatis, costis per totum divisis, nec marginem levem
attingentibus.

? or var. Dalmani, figs. 25, 26.

Omnino precedenti simillimus, glabelld, caudd, oculis—sed fronte cagitis rotundato
nec producto.

PHACOPS. 35

This is not a difficult species to recognize, once its peculiarities are mastered ; but it
occurs in a variety of forms, and these are rendered more obscure by the changes the
rock has undergone. It is common in the sandy schists of Tyrone, and not unfrequent
in North Wales and other places. Colonel Portlock thought it identical with the P.
macrophthalma of Brongniart and the P. Downingie of the Wenlock Rocks; and to
avoid the confusion of using these controverted names, proposed to term the combined
species P. Brongniarti, after the author of the ‘Crustacés Fossiles.’

But, as I have shown im thé Decades of the Survey (/. ¢.), these are really three very
distinct species, and we must limit Portlock’s name to the species described first by him.
His P. Murchisonit is only asynonym. But it is with some little doubt I include the
P. Dalmani, a form with rounded front, but otherwise exactly like the species with
which it is associated. As I find Welsh and Irish specimens with an intermediate
character, I do not think it can be wrong to unite these two, and I take the pointed form
to be the ¢, and the more rounded yv vary (P. Dalmani) to be the 2 form. The 3 is
the more common of the two.

Two inches long, elongated, and tolerably convex, the head occupying less than one
third the whole length; subtriangular, and with the front produced and recurved (in the
P. Brongniarti 8 ; semioval and with a rounded front in the ¢ form, P. Dalmani ;)
the glabella itself is of the same shape in both varieties, tubercular all over, contracted
at the base, expanded in front, but not convex, and with radiating lobes. 'The forehead-
lobe is subrhomboidal and transverse, the upper lateral lobe large, triangular, and over-
hanging all the rest, but not so large as to ‘render them obsolete. The mid-lobe is
directed backwards, and is parallel-sided, and about half the length of the front one.
The basal Jobe is transverse-linear, contracted at the sides, where it forms a tubercle, and
the neck-lobe is again broader and thicker and more elevated than the rest. This is less
conspicuous in the ? form. ‘The cheeks are triangular, and concave outside of the very
large eye, which reaches forward beyond all the lateral lobes, and backward to the neck-
furrow. It is considerably arched, rather depressed, and has numerous small lenses
(about eight in a vertical row, and in all 170 in each eye). ‘The eye-lobe or -lid is strongly
furrowed parallel to the lens-bearing surface. The space between the eye-lobe and the
glabella is convex, and of an oblong shape. Angles of the cheeks obtuse, not spinous.
Thorax with a convex, narrow axis, and with pleure which are steeply bent down at
about the first third of their length; the fulcrum placed within the middle point; the
ends of the pleure blunt and arched forward, and their facets large.

The tail is triangular, pointed in the ¢, obtuse in the ¢ form, rather convex ; with
a long conical axis reaching nearly to the narrow margin, and interlined strongly by
intermediate furrows, which project beyond them and quite reach the margin, undulating
it most strongly in the ¢ form.

I see no reason for separating the two trilobites quoted above as specific forms. All
the characters are more strongly pronounced in the form which I suppose to be the ¢,

36 SILURIAN TRILOBITES.

and which has both the apex of the tail and the front of the head more prominent and
produced than in the other variety. ‘The North Welsh specimens are intermediate, the
cheeks steeply bent down, the margin of the eye-lobe narrower, and the lenses
more numerous ; occasionally ten in a row, in the widest part of the eye.

P. macrophthalma of Brongniart, with which the first describer of this species united
it, has neither the obsolete basal lobes, nor greatly expanded glabeila, nor the large
eye of the one we have been describing. And there can now be no question of uniting
either of these with the Dudley fossil included by Brongniart (described above as P.
Svokesii), all subsequent writers having adopted the distinctions.

It is, however, worth while to compare our species with the fossil figured by Dr.
Pander, in his ‘ Beitriige zur Geogn. Russ.,’ pl. v, fig. 7, and pl. vi, fig. 9. It has large
eyes like ours, but the glabella-lobes differ considerably. And at all events, it is not the
L. macropththalma, to which he refers it.

Localities. — Caranoc, Tyrone, abundant; Kildare; Wexford; and Waterford, in
Ireland. Lilanfyllin and Llanwddyn, Montgomeryshire, in North Wales. (Mus. Pract.
Geology, &c.)

uv

Sub-genus—Cuasmors, Mf Coy.

Though not quite convinced that this is a definable sub-genus or section of Phacops, 1
adopt it becanse it conveniently bridges over the space between Acaste proper and the
typical species of Odontochile. The P. conophthalmus, Boeck, is the type of the section, and
has to perfection the enlarged upper lobes of the glabella and the expanded forehead-
lobe, while the tail is only of moderate size, and has but eight or nine segments.

P. macroura, again, 1s typical so far as the head is concerned, but has very numerous
segments to the tail, a characteristic still further carried out in such species as P. frvn-
cato-cuudatus, which may be considered as linking on the sub-genus Chasmops to Odon-
tochile, as P. Jukesii links it to the ordinary caste.

Altogether the group has a wide range, and tends to show the unity of the genus

Phacops.

Puacors (Crasmops?) Juxesir. PI. I, figs. 29, 30.

? Piracops scLErops, Dalman. Paleeade, t. ii, fig. 1, gy, icon mala, 1826.
Piacops Jukersit, Salter. Decades Geol. Surv., No. 7, Art. 1, p. 11, August, 1853.
== — Id., in Morris Catal., 2nd ed., 1854.

PHACOPS. | 37

P. (Chasmops vel Acaste) modicus, unciam latus, granulosus, capite transverso feré quam
longo ter latiore; glabella dilatatd, lobis omnibus distinctis. Glabclla subconvewa, frontem
mmpendens, late triangulata, anticée valdé dilalata, nec cum margine connata, posticé

_contracta, utringue triloba ; lobo basal transverso lineari, secundo paullo majore rotundato,
supremo maguo triangulato, frontalt maximo transverso oculos imminente, cervicali elevato.
Sulci axillares profundi. Gene lata marginale, transverse—angulis rotundatis ?, sulco
cervicali forte exarato, lined faciali impressa.

It may be doubtful if this species be not included in some of the varieties of
P. sclerops, Dalman; but it is clearly distinct from his typical form, as we know by
specimens in the cabinet of Sir R. I. Murchison. And it well deserves a name, being a
most characteristic form, which somewhat tends to connect the ordinary species of
Acaste with the more extravagantly lobed species of Chasmops. I scarcely know to
which sub-genus it should be more properly referred, and place it first. We have only
lwvo specimens.

The head is above an inch wide, and scarcely more than one third its length ; convex
and granulose, with coarse and fine grains equally all over. The glabella not convex, but
creatly dilated in front, and contracted behind to one fourth the width. ‘The forehead-
lobe is widely transverse, and overhangs completely the triangular upper lobe, which in
its turn is imminent over the mid-lobe, and about twice its size. ‘lhe middle lobe is,
however, wider than the narrow basal lobe, which is not reduced to a mere tubercle
on the sides, nor contracted to a much less width than the rather prominent
neck-lobe.

‘The cheek, strongly margined in front, is of a narrow triangular shape, and is deeply
divided from the glabella. The eye, much curved, is opposite to and covers the space of
the two upper lobes, and is itself overhung by the upper Jobe.

The facial suture is deeply marked outside the eye; it nearly bisects the cheek, and
runs parallel to the deep neck-furrow.

A young specimen does not differ in any material respects from an older one.

Locality. Carapoc Rocks of Gelli grin, near Bala, North Wales. (Mus. P.
Geology.)

P. (CuasMorps) Macroura, Sjogren, Pl. IV, figs. 1S—23.

Asaruus Powisi!, Murchison. Silurian Syst., pl. 23, fig. 9 (head only), 1837.

DALMANNIA AFFINIS, Salter, Memoirs Geol. Survey, vol. ii, pt. 1, pl. vy, fig. 5, 1848.

PHACOPS TRUNCATO-CAUDATUs, var. , AFFINIS, Id., in Decade Geol. Sury.. No. 2,
ISAS ISOS Gj sh

38 SILURIAN TRILOBITES.

ODONTOCHILE TRUNCATO-cAUDATA, M‘Coy. Synops. Foss. Woodw. Mus., t.i«, fig.
20 (21?) (not Chasmops Odini, same plate, figs.
22, 23), 1851.

Puacops MAcROURA, Angelin. Palzont. Suecica, t. vii, figs. 3, 4, 1852.*

P. (Chasmops) ovatus magnus, capite semilunari, vir quam longo bis latiore, tuber-
culoso, caudé elongatd submucronaté multi-annulatd. © Glabella pariim convexa, antic? valdé
dilatata, lobo frontali maximo triangulato oculum imminenti ; lobis lateralibus supremis magnis
triangulatis quam latis multo longioribus, medianis obsoletis, basalibus contractis, cervicali
lato. Gene conveve nec gibbe, declive, glabelld angustiores, angulis in cornua lata longa
extensis ; oculo majore, suleo circumdato, linea faciali impressd. Cauda magna trigona
convexa, apice acuto, axi lato per 4 longitudinis extenso, annulis 16; costis lateralibus
circa 16, feré rectis, viv interlineatis, sub apice radiantibus.

All the above names have at various times decorated or disfigured our fossil, which
labours under the combined disadvantages of being very common and conspicuous, and
seldom at all perfect ; and also of belonging to a group of closely allied species which occur
in company, and have been hitherto always badly figured. I can hardly hope to have
remedied a// these defects, and only give those synonyms of which I am assured. The
name Phacops conophthalmus, under which it is generally known in cabinets, really
belongs to a species with short head-spines, smaller eyes, wider cheeks, and altogether a
more transverse form of head, and a short tail. We must wait for a more complete
knowledge of this group of trilobites ; and meanwhile our figures represent truly the most
conspicuous of these forms, and certainly that figured by Prof. Angelin. The numerous
ribs of the tail and the great head-spines readily distinguish it.

The P. bucculenta, also figured by Angelin, has a large, many-ribbed tail, but has
only a small pair of lateral glabella-lobes mstead of the great encroaching pair distinctive
of the P. macroura, aad which have procured for this grotesque-looking species the name
among collectors of the ‘ Cat’s-head Trilobite.’

There are other allied species both in Scandinavia and North America; but the group
appears to be peculiar to this northern zone, and does not occur in mid-Europe, as M. de
Barrande has specially remarked. ,

General form rather narrow, ovate, blunt but abruptly aoeaeies in front, and shortly
pointed behind. The head is about as long as the tail, and not quite twice as broad
as long; very convex; semilunar, with a very wide glabella, larger than the cheeks, the
sides of which converge behind at about 50°. The cheeks are very convex, deeply
margined, and produced behind into exceedingly broad, flat, and rather lengthened parallel
spines, at the inner angle of which the strong marginal and still stronger neck-furrow
meets.

* The cover of this excellent folio is marked 1851; but in order to preserve priority of date, it is

necessary to be exact. It seems to have appeared Jan., 1852.

PHACOPS. 39

The lobes of the glabella are as follows:—The forehead or frontal lobe transverse,
rhombo-trigonal, depressed in the centre, twice and a half as wide as long, rounded-
truncate at the upper angles, and only a very little overhanging the position of the eyes.
The great lateral “cat’s-ear” lobes are right-angled triangles, with the corners rounded
off, their larger angle inwards, and only slightly sinuous above, and they occupy in length
full half the side of the glabella, and reach more than one third across it, bounded on all
sides by very deep furrows. A narrow, triangular space is left between the bases of these
lobes for the lower pairs; the middle lobes are minute, and mere tubercles; the basal
lobes more extended, but still narrower than even the base of the upper lateral lobes,
which completely overlap them. ‘The neck-furrow
is very strong, and equal across ; the neck-segment
of equal width throughout, but its whole breadth
is scarcely one half that of the frontal lobe.

The axal furrows are very deep, and tolerably
straight, the cheeks rising very convex from them,
bearing the small, strongly lunate eyes.* These
have about 160 lenses rather small, and very little
prominent, and the pits containing them have on
the interior cast an elevated rim or border. The
eyes are placed opposite the centre of the frontal
lobe, about half way up the cheek, and their own
width from the glabella; a deep channel surrounds

its base. All the furrows of the head are deep, —_—P macroura, a perfect head in Mr. H. Edgell’s
collection: the eye magnified.

the marginal one especially so, and the neck-
furrow is much curved to follow the descent of the great head-spines. hese latter are broad,
flat horns, pressed against the body, and extend back a great way, as shown in our woodcut.

The surface of the head—the glabella especially—is largely tubercular ; and in fig. 20
a curious double row of deep puncta runs half way down the forehead-lobe from the emar-
ginate front. But this is perhaps not repeated in other specimens.

The facial suture is not strictly marginal in front, but a little above the margin.
Outside the eye it takes a forward curve, and here it lies in an impressed groove. ‘The
labrum (fig. 21) has a very broad, arched base, and a blunt-pointed end. The body of
the labrum is strongly separated from the wings, and its sides are parallel for a short
‘distance, then converge to the rounded obtuse point. There are two deep concentric
furrows ; the outer one quite continuous, very strong, and remote from the apex. Above
these the organ is convex and roughly tubercular; beyond them it is flat. here is a
deep perforation (a) in the broad basal wing, which indicates the place of the ascending
process of attachment.+

* T think Prof. Angelin’s figures are not correct as to the eyes, The cornea must have been thin,
+ This varies in shape in various species. ‘The form above indicated is a rare one.

40 SILURIAN TRILOBITES.

‘he tail, from very perfect specimens (figs. 19, 22, 23) is subtriangular, with rounded
sides and apex; pointed, highly convex; the sides regularly so, without any flattened
border. The axis is broad, and very gently convex; much more than half of the width
of the broad limb, regularly conical, and reaching four fifths the length of tlie tail. It is
annulated to the very tip by sixteen sharp rings. ‘The sides are deeply grooved by
sixteen* nearly direct strong furrows, faintly interlined throughout, which gradually
radiate downwards, till from the tip of the axis they become longitudinal. ‘Three or four
longitudinal ridges run from the tip to the end of the tail, thus completing the fan-like
arrangement.

The incurved portion of the tail, scen in the small specimen (fig. 23), is narrow and
granulated, as the whole tail appears to have been.

Locality.—Caravoc Sanpsronrs of Shropshire ; plentiful in many places. (Cabinets of
Messrs. Lightbody and H. W. Edgell ; and in the Ludlow Museum, and Mus. P. Geology).

P. (Cuasmops) conopHtHaLMmus, Boeck? PI. IV, figs. 24, 25, and Pl. VII, fig. 25.

TRILOB. CONICOPHTHALMUS, Boeck. Gea Norvegica, i, 4, 1838.
PHacors — Emmrich. Dissert., 21, 1845.
CaLYMENE ODINI, Hichwald. Sil. Syst. Esthland.
—_ — De Verneuil. Geol. Russia, t. xxvii, fig. 8.
Puiacops scLErops, Burmeister. Org. Trilob., ed. 2, tab. iv, fig. 5, 18416.
— conopnutHaLmus. Ibid., p. 91.
— _Fewinus, Salter (MS.). Ibid., Appendix of Species, p. 125.
— CONOPUTHALMUS, Angelin. Palzont. Suecica, t. vii, figs. 5, 6, 1852.
— = Salter. Decades Geol. Survey, vii, Art. 1, p. 7 (exclude other
synonyms than those above), 1853.
Cuasmops Opint, D/Coy. Synopsis Woodw. Mus., t. i G, figs. 22, 23, 1851.

P. (Chasmops) ovatus, capite valdé transverso, quam longo feré ter latiore, granuloso
convewo [caudd brevi, 8—9 costatd|. Glabella convewa, anticé valde dilatata, lolo
Jroutali maximo triangulato, oculum parvum imminente, lobis lateralibus supremis magnis
rotundato-trigonis, medianis obsoletis, basalibus linearibus, cervicali lato. Gene conveve
Sere gibbe, marginate, angulis in cornua brevia extensis, oculo brevi, lined Jaciali impressd.
Cauda |associata| lata, punctata, vie marginata, axi conico 9—10 annulato; costlis
lateralibus 8 arcuatis, duplicatis.

‘The head of this species differs at a glance from the one above described, in being so
much more transverse, only half as long as it is broad, and rather semicircular than
semilunar. Though fig. 25 (copied from my own original figure in the ‘Cambridge
Synopsis’) is not quite perfect—it is only the internal cast—there is enough to show that
it agrees better with Angelin’s P. conophthalmus than the other species; and the tail

* Angeliu’s figure has 19 axal, and 18 side ribs.

PHACOPS. 4]

figured with it in the same work, will agree pretty well with Burmeister’s figure of P.
conophthalmus, in his later and improved edition ;* much better than with Angelin’s
figure, which surely represents the tail as too pointed, and he describes it with twelve lateral
ribs to the tail. We are still at sea about this species, but must accept Angelin’s figure
as the type, as he has access to all the described Swedish species. I only describe
our own, and believe it will by and by constitute a new species.

The head is transverse, semicircular but obtuse in front, and more than twice
as wide as long; very convex; granular, not tubercular; and with the wide glabella
occupying much more than one third of the head. It is nearly a right-angled triangle,
with the corners rounded off. ‘The forehead-lobe is widely transverse, and considerably
overhangs the eyes. ‘The upper lateral lobes are large, but not expanded forwards, only
behind, and rounded-trigonal; their transverse diameter fully equal to, if not greater
than the fore and aft measurement. The mid-lobes are quite obsolete, and the basal one
transverse-linear, and smaller than the neck-lobe. ‘The cheeks’ are equilateral triangles,
very convex, and bear centrally the small eye, which is subtended by a much deeper
furrow than in P. macroura. The neck-furrow is strong, and continuous with the marginal
furrow, but the margin is in no part very broad. Head-angles short-spinous.

The tail (which occurs in the same locality, and probably belongs to the same) is
transverse, “its length nine lines, against a breadth of fourteen lines; the axis convex, of
ten segments, and about two thirds the width of the side-lobes in front; abruptly
narrowed after the fifth segment. There are about eight lateral segments” (M‘Coy).
The ribs are much arched, and reach quite to the margin; strongly interlined throughout.
The surface of the tail is strongly punctate.

This obtuse, short caudal portion is very like that figured by Burmeister in the Ray
edition of his work. It is more like the tail-piece of a large Calymene than a Phacops. Not
having access to the Cambridge specimens at present, I had thought of leaving this and
some other doubtful species for a supplement, but prefer to present it, with other frag-
ments, in our Plate VI, and so complete what we at present know of this obscure
species. Collectors will do well to pay special attention to this fossil, as it is a charac-
teristic northern form.

Locality—Carapoc suates of Llansaintffraid, Glyn Ceiriog, south of Llangollen,
North Wales. Also at Acton Scott, in Shropshire (Mr. H. W. Edgell).

I omit other localities, but one or the other of the above two species occur throughout
North Wales, at Llanfyllin, Llanwddyn, and Meifod, Montgomeryshire; Pwllheli and
Bettws-y-coed, Caernarvonshire. In South Wales, at Llandeilo, In Westmoreland, at
Coniston, Troutbeck, and Rother Bridge. In Clare and Kildare, Ireland.

* Ray edition, 1846. He describes the tail as having nine lateral ribs—the number present in a
specimen from Christiania in the Mus. Pract. Geology.

6

42 SILURIAN TRILOBITES.
P. (Cuasmops) AmpHoRA, Salter. Pl. IV, fig. 16.
Puacors (DALMANTA) ampHoRA, Salter. Decade Geol. Survey, vil. Art.1,p.12. 1853.

P. (Chasmops) caudé magna biunciali elongata, convexissimd, fere semicylindrica.
suleis awalibus fere obsoletis. Axis latus nec eminens, marginem angustum inflecum haud
attingens, in annulos 16 subplanos divisus, apice obtuso. Latera valde curvata defleza,
costis 14—15 planis, sulcis acutis separantibus, costé qudque lined mediand levi elevata
sub cortice tenui impressa ; apice obtuso (emarginato ?).

This species must be closely allied to the preceding. It differs only in proportions, but
markedly so, being greatly more convex in the only portion we know—the tail; it is
almost semicylindrical in shape, and the axis much less distinct from the sides than in P.
macroura. It is also, but somewhat more remotely, allied to P. ¢runcato-caudatus.

The large tail, which must have been fully two inches long, is but a little more than this
in breadth. It is more than half a cylinder, the curvature being remarkably regular and
even, the axis scarcely projecting beyond the general convexity, and scarcely divided from
the sides by any depth of axal furrow. ‘The axis is broadly conical, and below rounded
off towards its apex ; it reaches fully five-sixths the whole length of the tail; and is made
up of sixteen rather flat rings. The four or five front ones ‘show a false articular surface,
distinctly ; the real articular surface is very large and distinct.

The side-lobes are in reality half as wide again as the axis, but on a front view do not
appear so, owing to the great convexity ; the surface is curved steeply down, and is scored
by fifteen deep sharp furrows, separating sixteen prominent flat nbs, much wider than the
furrows. Each rib has an interrupted chain-like dividing line down its middle. The same
occurs, somewhat exaggerated, beneath the crust, on the cast. But the perforations here
are so arranged as to leave a crest-like ridge. The dividing lines extend nearly to the end
of the ribs, which cease rather suddenly near the steep, almost vertical or inflexed, marginal
rim.

The shell or crust of this species is remarkably thin. Except some species of Homalo-
notus, 1 do not know any kind of trilobite which has so cylindrical a form.

Locality. Carapnoc Limestone of Grug, N. of Llandeilo, Carmarthenshire. Collected
and presented to the Mus. Pract. Geology, by Mr. Williams, of Llandeilo.

P. (Cuasmops) TRUNcATO-cauDAtus, Portlock. PI. IV, figs. 18—15.

PHACOPS TRUNCATO-CAUDATUS, Portlock. Geol. Rep. Tyrone, 1. ¢., pl. ii, figs. 1—4,
1843; Paradowxides Bucephali, ibid. (labrum only),
pl. i, fig. 8.
= — Salter. In Morris, Catal., 2d ed., 1854.
a — (Datmanta) Id. Decade II, Geol. Survey, Art. 1, p.
7, 1849 ; (exclude the synonyms of D. affnis, for
which see P. macroura).

PHACOPS. 43

P. (Chasmops) granulatus, capite antice truncato, oculis maximis subdepressis, pleuris
obtusis, fulcro ab axe valde remoto. Cauda axe 18-annulato angusto, costis lateralibus
14—16, apice emarginato.

An obtusely ovate form, strongly truncate in front, and obtusely pointed behind. The
head widely transverse, fully two and a half times as wide as long, and with the glabella so
expanded along the front as to occupy more than half the width of the head, and over-
hang the middle of the large eyes. Thence the glabella abruptly narrows to half this
width, sloping inwards to the base of the middle lobe ; but from this point it is again parallel-
sided to the base (in P. macroura the shape is triangular, here it is turbinate).

The upper glabella-lobes are quite overhung by the frontal lobe, and are not greatly
larger than the succeeding lobes. They are right-angled triangles, with the obtuse right
angle outwards, not inwards as in the preceding species. ‘The space between them is fully
equal to the width of the lobes themselves; their length is two thirds that of the great eye.
The middle lobes are rather smaller, narrower, and somewhat linear, but tumid at the
sides—(and not overhung and rendered obsolete as in P. macroura). The basal lobes are
still narrower, more linear, and less tumid ; the neck-lobe of the same shape as the basal
lobes. ‘The whole glabella, as well as the cheeks, and all the rest of the head is thickly
covered with large granulose tubercles.

The cheeks are not large, and are chiefly occupied by the semilunar eyes, which reach
from the front furrows nearly to the neck-furrow. ‘They are much curved, the eye-lobe
strongly margined, with an angular fold along the middle. Cheek-spines large.

Axis of the body-rings gradually widening behind; rather convex, especially along the
middle part, which is wholly covered with granules. The sides of the axis are nodose on
every joint. The axal furrows strong, the pleuree not very much wider than the axis, flat
as far as the remote fulcrum, which is fully two thirds out. Pleural groove deep, very
oblique, and leaving a strong node on the proximal or inner end of the pleura, against.
the axis. This is a conspicuous character. ‘Tubercles, larger and smaller ones, are visible
over the whole surface. ‘T'ail broadly half-ovate, convex, but regularly so, except the con-
cave narrow margin. ‘The axis not very prominent nor strongly separated from the sides,
tapering, narrow, with straight sides, composed of eighteen rings nodular (as the axis of
the body, but on a smaller scale). Sides of tail depressed, with fourteen or sixteen
flattened radiating ribs, with a somewhat sigmoid curve; the ribs separated by sharp
furrows which run almost tothe margin. The ribs are granular throughout ; there is an
imperfect double row of granules on each flattened rb—the space between the rows
representing the interlining furrow, which is not present in this species.

The apex of the tail is, as in most of the allied forms, emarginate and a little raised ;
a ridge runs to it from the angular termination of the axis, as in kindred species.

The /abrum or epistoma, fig. 15, has the wide arched base characteristic of the sub-
genus. It is gently convex and somewhat angular in form (but subparallel at the base)
with a shallow notch for the ascending process. The concentric pair of furrows are deep ;

41 SILURIAN TRILOBITES.

the outer pair continuous as a marginal furrow, the inner very oblique. The apex is
angular, but blunt.
Localities. Caravoc of Desertcreat, &c., Tyrone. (Mus. Pract. Geology).

Puacoprs (Cuasmops) Baityi, n. sp. Pl. VII, figs. 21—24.

P. (Chasmops) satis magnus, capite subangulato; glabellé dilatatd, lobis omnibus distinetis ;
cauddgque (associatd) rotundaté multiannulatd. Glabella longa elevata tuberculosa lobo
antico rhomboideo transverso, lobis lateralibus inequalibus, supremo magno rotundato trigono,
secundo paullum abbreviato, basali majori, cervicali expanso. Oculi elevati. Cauda semi-
ovalis, apice rotundato obtuso ; axe longo conico 10—11-annulato ; costis lateralibus \1
planis, arcuatis, lineisque intermediis distinctis ad apicem und cum primariis connatis.

It is scarcely doubtful that this is a Chasmops rather than Odontochile. It certainly has
many affinities with P. truncato-caudatus, to which Mr. Baily referred it in the Irish col-
lection. He has judiciously preserved every fragment, and in this way we have been
enabled to reconstruct the species.*

The head is rather elongate, the glabella somewhat depressed and widely clavate, broad
above the wide forehead, and actually overhanging the eye, and narrowed behind; all the
lobes distinct and somewhat radiated. The forehead-lobe is transverse and rhomboidal,
separated by an arched furrow from the rounded, triangular, upper lateral lobe, and this
by an oblique downward furrow from the much smaller mid-lobe, which is triangular in
the reverse direction. The basal lobes are large, and tumid at the sides; the cervical lobe
is wide. The eyes prominent, and placed rather forward, on a somewhat sharply elevated
cheek. The margin of the cheek narrow, and not strongly defined. The facial suture
runs in a broad ogive some distance within the front margin, which is slightly angulated.

Of the tail we have one external and three interior casts, which show it to have been a
large semioval plate, broader than long, but rather abruptly narrowed behind, and with a
rounded obtuse end. ‘The axisis narrow and conical (but broader than in P. trwncato-cau-
datus), reaches five-sixths the length of the tail, and has ten or eleven rings at least. The
axal furrows are deep, and the sides are convex, and scored by eleven narrow sharp furrows ;
the ribs between which are flat and interlined all along, much in the same way as in P.
macroura. ‘The wpper ribs are duplicated very strongly. The margin is very narrow.

It is very like P. macroura, above figured, and differs from P. ¢runcato-caudatus,
fig. 13, both in the shape and proportions of the glabella-lobes, and in the much narrower
segments of the tail, and it does not need comparison with other British species.

Locality.—Caranvoc status of Tramore, Co. Waterford. (Mus. Irish Industry, Nos.
B 647, 650, 652.)

* Many species are lost from want of care in the collocation of fragments of specimens. Very often,
indeed, in slate-rocks, the species must be truly reconstructed from the disjecta membra, and with
judgment this may generally be safely done.

PHACOPS. A5

Section. —ODONTOCHILE.

If there were some doubts of the limits of the subgenus Cuasmops, there can be none
at all of the general character of that which Emmrich called Da/manza, and which name was
rightly changed to Odontochile by Corda, Dalmania having been in previous employ.

Large expanded forms, with the glabella wider in front, and with the lobes nearly equal
or only gradually increasing forwards ; a depressed habit, and a caudal shield composed of
many segments (technically more than eleven), give a combination of characters easily
enough recognisable among the large Trilobites, which chiefly occur in Upper Silurian
rocks ; a few began in the Lower Silurian, a few extend into the Devonian ; but the bulk
of the subgenus are to be found in Wenlock and Ludlow rocks, and the genus is world-
wide.

We have in this section the largest and most conspicuous of the Phacopide. And
while the section <Acaste is chiefly Lower Silurian, and Chasmops wholly so,—the large
flattened species which form this group, with their numerous tail-segments, are almost all
Upper Silurian. They commence, so far as I know, in the May Hill Sandstone. The most
renowned of them all is the P. caudatus, and it is at the same time the most typical.

I’ commence with those species in which the caudal portion is least extravagantly
developed:—

Psacops (OpoNTOCHILE) OBtTusicauDaATuS, Salter, PI. I, figs. 42—45.

PHACOPS OBTUSICAUDATUS, Salter, in Sedgwick and M‘Coy’s Synopsis Foss. of the
Woodw. Mus., pl. iG, figs. 15, 16.
— — Id. Mem. Geol. Survey, Dec. II, pl. i, p, 7, note.

P. (Odont.) uncialis, capite elongato semielliptico tuberculato ; caudd brevi. Glabella
longa, lobo antico magno rotundato, lateralibus subequis, radiatis, sulcis longis profundis.
Oculi elongati, antici. Gene angusta scrobiculate, spinis modicis. Cauda trigona, apice
angulato, axe rotundato longo 12-annulato ; lateribus recti-sulcatis, sulcis 10, omnibus dupli-
catis ; margine angustissimo,

This is known only in one locality ; but it is a common fossil there, and is accom-
panied by but very few other fossils. It is a gregarious species, occurring in crowds upon
the faces of the “ bated” or cleaved rock in Coldwell quarry, Westmoreland.

The head is half elliptical, frequently an inch and a half long, the width then being

AG SILURIAN TRILOBITES.

about two inches; the general form that of a pointed arch; the glabella narrowed, long-oblong,
not much broader in front than behind, the forehead-lobe as long as the rest of the glabella
(including the prominent neck-segment), and almost round. The side-lobes are very strong,
and divided by deep, radiating furrows, deepest and strongest inwards, and reaching far
towards the centre. ‘The upper lobe trigonal, not greatly larger than the mid-lobes ; the
basal lobe narrow, almost linear externally (and clavate in the cast). The whole glabella
covered by coarse tubercles and fine granules intermixed.

The eyes are large, reniform, elongate, compressed laterally instead of longitudinally, and
placed in advance of the centre of the cheek, half their own length from the neck-furrow,
and touching the glabella in front. ‘The cheeks curve steeply down, are scrobiculate, not
tubercular, margined nearly all round by the narrow furrow, and provided with head-spines
half as long as the glabella.

The facial suture curves largely forward outside the eye, and cuts the margin about
half-way up the cheek.

We have no body-rings. The tail is broadly triangular, pointed below, but not pro-
duced into any mucro, and with a very narrow equal margin. The conical and very
convex axis nearly reaches the tip, annulated all the way down, and has about twelve sharp
rings. ‘The sides are strongly radiated ; nine or ten strongly duplicated ribs running on
each side to the narrow margin. The intermediate furrows are straight at their origin
and terminations, and at the latter point they are so deep as to make the margin
pretty strongly undulate.

Locality—Caranvoc state of Coldwell, Westmoreland ; in beds over the Coniston
limestone. [Brit. Mus. Mus. P. Geology. Woodwardian Museum, &c. |

Puacoprs (Oponrocns1n) mucronatus, Brougn.? PI. IV, figs. 11, 12.

[Enromouiruvs, Linneus. Iter Vestrogoth. p. 88, cum fig. 1747.
Enromostracites caupatus, Wahlenberg. Nova Acta Reg. Soc. Upsal, tom. viii,
p. 28, t. ii, fig. 3, 1821.

Asapuus mucronatus, Brong. Crust., p. 24, t. ili, fig. 9, 1822.

= — Daiman. Paleade, p. 236, t. il. fig. 3, a, 6, 1826.

a —— Hisinger. Lethzea Suecica, p. 13, 1837.
PHACOPS — Emmrich. Dissert. (1839); Neues Jahrbuch, 1845.

yee — Angelin. Paleont. Suecica, tab. viii, fig. 1, 2, 1852.)
_ — Salter. Decade VII, Art. 1, p. 12, 1853.

P. triuncialis et supra. Glabella conveea, antice parum dilatata, utrinque lolis tribus
subequalibus transversis, sulcis longis satisque profundis sese separatis. Cauda triangularis
acuta; axe convexo limbo plano haud equali, in annulos 9 et appendicem diviso [appen-
dice in apicem caude brevimucronatum percurrente 7) ; lateribus costis 8 planis, sulcis 7

PHACOPS. A7

angustis acutis valde curvatis et cum tot lineis intermediis profundioribus ad apices confusis ;
margine angusto subundulato.

From the number of authors who have described the Swedish species, it must be a
common one, and yet there is no good figure extant. Angelin’s, the latest, is worse than
Dalman’s, which appears to be the best, for Wahlenberg’s figure is so very unlike the fossil
that, were it not for his description and statement of locality, it would be impossible to
recognise it. Brongniart has only copied Wahlenberg, who appears to have been chiefly
attentive to the course of the facial suture, and allowed his artist to take his own course.

To make evident the distinctions between our British fossil (which is certainly very
nearly allied to the Scandinavian one), and the true P. mu-
cronatus, I subjoin a figure from one of Sir R. I. Murchi-
son’s specimens.

It will be seen readily that the head we here figure
has less regular and equal lobes than the British one, and
this is a character of high importance in the family. And
the tail, while it has a great resemblance, has not the
strongly curved and deeply impressed ends to the side fur-
rows, which give so conspicuous a character to our fossil, I
am justified, therefore, in placing a ? against the same:
indeed, had it not been already referred in the Decades
to P. mucronatus, I would have preferred keeping it dis- Swedish specimen of P. mucronatus.
tinct under thename P. appendiculatus. For the present I sa ea Oe Tie
leave it in doubt.

Description. Our specimen of the head only shows a broad glabella with three equal
pairs of lobes, which are divided by nearly straight somewhat radiating furrows: the two
lower pair of lobes are linear and direct ; the upper somewhat clavate, but not triangular,
and separated by a slightly sinuous furrow from the wide transverse forehead-lobe. All
the lobes are tumid ; and a convex median ridge, of equal breadth throughout, divides the
lobes of one side from those of the otlier. A deep central pit in the cast occurs upon the
forehead-lobe, as in many species.

Of the triangular tail we have more complete evidence, though even of this only a
fragment.

The axis is broad and convex, of nine strong rings, anda terminal portion or appendix,
of which we do not know the length. While the axis is convex, the sides are very flat,
have the forward edge strongly curved, and are deeply grooved by seven arched duplicated
furrows. The backward curve of these near the margin is considerable, and the secondary
furrows are as strong or stronger than the primary, and coalesce with them at the tips in
deep grooves, so as to undulate the very narrow margin considerably.

Vestrogothia.*

* “Toc, Nat. In stratis argillaceis Z, Vestrogothie, in montibus Alleberg et Mossberg, alibique.”’
Angelin, ‘ Paleeont. Suecica,’ part 1, 1852. ’

48 SILURIAN TRILOBITES.

Locality —Caravoc suates of Pen-y-Rhiw, west of Bala, over the voleanic ash-hed.
(Mus. Pract. Geology, figs. 11, 12.) The other locality given in the Decade above quoted is
erroneous; the specimen referred to is a species of Ogygia, which will be figured

further on.

Puacoprs (OponTrocHILE) IMBRICATULUS, Angelin 7? PI. IV, fig. 10.

[Puacors IMBRICATULUS, Angelin, Paleont. Suec. t. vil, fig. 5, 1852. ?]

This I do not wish yet to name. It is a new British species, but scarcely perfect
enough to assure me it is not the same as one of Green’s published casts.

The pygidium is seven-eighthsof an inch long, excluding any mucro it may have possessed,
and the width about one and a half inch. It is rather flat, the centre raised in a low pyramidal
form, and the sides sloping outwards and gently curved down near the very narrow, regular,
smooth margin. We have two specimens, in both of which the axis is not one fourth the
entire width at tip; itis regularly conical to within a very short distance from the margin,
annulated by about twelve or thirteen flattened rings, and has an appendice beyond, as far
as the prominent tip ; the rings of the axis are angulated forwards. ‘I'he axal furrows slight
but distinct, the pleural furrows on the side-lobes widely patent, and nearly straight,
except a slight angular backward bend near their abrupt ends. ‘There are ten lateral ribs,
all strongly duplicate to their very tips; the intermediate furrows not keeping quite
separate, but combined at the ends, and nearly as strong as the principal ones. This strong
duplication gives a very striking character. ‘The incurved margin is regular and narrow
all the way round.

It is very like P. mucronatus from Sweden; but perfect specimens of that species (see
woodcut, supra p. 47) show that species to have had a narrower tail with wider margin,
and the head is flattened, with arched lower glabella-lobes. It must be distinct. But
the P. imbricatulus, on the other hand, is quite like ours; it has ten dichotomous side-ribs,
and a very distinct margin. The axis has ten distinct, and five or six terminal joints.
The tail is mucronate. Altogether it is very like our species.

Locality—May Hitt Sanpstone (Uprprr Luanpovery), of Nash Scar, Presteign,
collected by Mr. J. E. Davis, of the Middle Temple. (Mus. Pract. Geology.)

PHACOPS. 49

Ps. (OpontocuiLz) caupatus, Briinnich. PI. III, figs. 4—18, and Pl. IV, figs 1—5,
including varieties.

TRILOBUS CauDATUS, Briinnich. Kjobenh. Sellsk. Skrifter, Nye Samml., vol. i, p. 392,

1781.
— — Schlotheim. Nachtrage, 35, 11, 1823.
ASAPHUS — Brongniart. Crust. Foss., t. ii, fig. 4 (not iii, fig. 9), 1822.

—_ —_ Dalman, Palzade, t. ii, fig. 4, 1826.
a _ Green. Monogr. Tril. N. Amer., cast 17, 1832.
= — Buckland. Bridgw. Treat., pl. xlv, figs. 9—11, 1836.
ae — Murchison. Sil. System, pl. vii, fig. 8 @; and A. tuberculato-
caudatus, ibid., fig. 8 6, 1837.
—_— — Milne-Edwards. Crust., vol. iii, p. 308; and 4. tuberculato-
caudatus, 1840.
-—— myops, Kénig. Icones Sectiles Foss., fig. 53, 1825 (our Pl. III, fig. 13, is
from the original specimen in the British Museum).
PuHacors caupatus, Emmerich. Dissert., 1839.
— — Goldfuss. Neues Jahrb., 1843.
— — Burmeister, Org. Tril., 2nd edit., t. iv, fig. 9, 1846.
= —_— Salter. Decade ii, Geol. Surv., 1849 (exclude syn. P. lon-
gicaudatus), pl. i, figs. 1—12, and fig. 15.
DaLMANIA CAUDATA, Emmerich. Neues Jahrbuch, 1845.
— — Salter. Memoirs Geol. Surv., vol. ii, pt. 1, 1848.
ODONTOCHILE caupATa, M‘Coy. Synopsis Pal. Foss. Woodw. Mus., p. 160, 1851 ;
Pl, III, figs. 4—17.
Var. a, VULGARIS. Most of the above synonyms, PI. III, figs. 4—17.
Var. (3, TUBERCULATO-CAUDATUS, Murchison. PI. IV, fig. 1.
Var. y, NEXILIS, Salter. PI. IV. figs. 3—5.
Var. 6, acuLEATUS, Salter. PI. ILI, fig. 18.

P. (Odontochile) magnus, 3—4-pollicaris ; ovatus, sub-convexus, capite angusto, fronte
plus minusve angulato. Oculi magni, pyramidati. Pleure sulcate (fulcro ad dimidium
posito) postice recurve. Cauda apice brevi-mucronato, avi 11—12-annulato; costis
lateralibus 7, rarius 6, arcuatis, duplicatis, ad marginem levem abrupté terminatis,
recurvis.

Four of the varieties are here figured, and I have no doubt there are others. Those
selected illustrate the very close connection that exists between this fossil and the so-
called species P. longicaudatus.

In the Decade of the Survey above quoted I ventured to unite these two species, and
have still little doubt that the series of figures here given will convince naturalists that all
are derived from one stock. But it will not be so easy to convince paleontologists ; and

7

50 SILURIAN TRILOBITES.

as there really are definite characters on which we can rely, it is thought best to follow
the general practice, and describe them separately.

The cabinets of Dr. Grindrod, of Malvern, Mr. E. Hollier, Mr. Tennant, Mr. Mushen,
and the British Museum, have furnished the chief materials.

Description.—Four or five inches long; ovate ; length as to width varying from 10 to
6, to 8} to 6; gently convex; the thorax longer than either head or tail ; the latter about
equal to the head, excluding the produced mucro ; axis of the body much more than half
the width of the sides.

Head semicircular, exclusive. of the slightly produced front or the long stout posterior
horns, which are broad at the base and reach the seventh or eighth thoracicring. Glabella
coarsely tubercular, widened above, more than one third the width of head; the forehead-
lobe a transverse rhomb, separated from the upper side-lobes by deep, broad, oblique
furrows, which nearly meet; the lateral lobes and neck-lobe all nearly equal in width, and
together equalling the forehead-lobe ; the first and second lobes run straight across, and leave
but a narrow ridge down the middle; strong axal furrows separate the glabella from the
triangular cheeks, on the surface of which the large pyramidal eyes occupy a variable ex-
tent; a lunate depression surrounds their outer edge, and this is sometimes extended
over more than half the width of the cheek, sometimes barely half, giving a considerable
difference in appearance. ‘The length of the eye, which is sharply curved, is uniformly
from the first basal furrow to the middle of the upper one; eyelid with a deep concentric
groove ; lentiferous surface considerably broader forwards ; lenses about 240, 8 or 10 in
a vertical row. In several perfectly preserved specimens the cornea is present, and it is
distinctly convex over each lens, the intermediate surface being ornamented with tubercles
and granules, so as to leave no doubt of its being the true exterior; it is, too, continuous
with the other portions of the preserved shell. ‘The cornea does not rise, as in some other
species, into elevated ridges between the lenses, but is flat in some specimens, in others
it sinks down between them. Occasionally a lens (or two) is undeveloped and very small,
among other perfect ones. ‘The facial suture exactly circumscribes the glabella in front,
falls perpendicularly to the eye, and arches outwards and upwards from its lower angle to
the outer margin of the head, on the lower face of which it extends along the margin further
back than on the upper surface (PI. IV, fig. 4). The cheek-pieces are united in one (as
in all the genus) across the front, and there is no extra piece (or rostral shield) inserted
between them above the labrum.

The latter is parabolic, obtusely pointed, the sides a little waved, and the base of
attachment extended ; a transverse furrow within the lip is connected with a marginal
longitudinal one on each side ; a pair of lateral strong indentations indicate a second furrow
above.

Round the head a strong furrow separates a broad margin, but ceases at the base of the
spines, and there nearly meets the equally strong neck-furrow, which is arched down at
its end. ‘The margin in front of the head is more or less produced into an obtuse point.

PHACOPS. 5]

Thorax with the central lobe not separated by any strong furrow from the pleure,
which in English specimens are half as wide again as the axis; the axis is a little fusi-
form, not broader than the base of the glabella, and either has the rings smooth, tubercled
at their outer edges, or with two tubercles on the central prominent part. All these varia-
tions occur on the same thorax. The front pleure are flat for the first half, then gently
curved down, and a little backwards, at the fulcrum ; they are divided by a moderately
strong curved furrow for most of the length, and their edge sharpened anteriorly (the flat
surface not crossing the furrow, as in Acaste), for rolling or bending. The extremities are
truncate, and pointed at the hinder angle; posterior pleuree with the fulcrum at less than
half, much more curved back and strongly pointed, overlapping the upper corners of the
tail. Whole surface of thorax finely granular.

Tail with the sides meeting below at nearly a right angle, and produced more or less
to a sharp point beyond this; axis not much raised, and gently tapering, ending a little
abruptly at some distance from the point ; it has eleven or twelve ribs, which are occasion-
ally tubercular, like the thorax, sometimes much so; the sides have six, seven, or some-
times eight narrow ribs, strongly arched down at their ends, where they abut suddenly on
the smooth margin ; each is sharply defined behind, and duplicated on its forward edge
by a fine rib along its whole length. ‘The number of ribs appears to be as great in
the young trilobites as in the adult form.

The above description, extracted from the Decade, will serve for the general account
of the species. I distinguish the following varieties more particularly.

Var. a, vuteaRis. PI. III, figs. 4—17.

Form narrow-ovate. Head broad, rounded, or slightly angulated only in front. Glabella
as broad as the cheeks. Tail truly triangular, simply pointed, scarcely at all acuminate.

There is no essential difference becween any of the specimens of this common variety.
All have the rounded or arched front margin (not at all produced) to the head; the
glabella at its widest part much more than one third the whole width of the head. The
length of the head as near as possible half the width of the same ; the axis broad ; the tail
shorter than the width, and simply pointed, with a very short mucro, or none at all.

They vary a little among themselves in the following particulars. Some have the
glabella more strongly marked out, and more decidedly narrowed behind. Some have
the glabella-furrows a little deeper. The eyes are larger in some (as in the varieties of
P. Downingia, before described), and more prominent ; but I have elsewhere referred these
differences to sex. - The male had probably more prominent eyes.

Some specimens have the characteristic tubercles on the sides of the axis, and the
central ones on the tail much stronger than others. We have figured these tubercular
varieties in Pl. III, figs. 15—17. As these seem to be chiefly characteristic in the young
state, and are much more obscure in the full-grown animal, I will here notice them par-
ticularly as they occur in the young and older states.

52 SILURIAN TRILOBITES.

Young specimens. Pl. III, fig. 15; Pl. IV, fig. 2 (see also Decade 2, Geol.
Surv., pl. i, fig. 7).

These differ in several particulars from the adult. The head-spines are smaller in
proportion, and the head-margin very narrow. The tail, too, is much smaller proportionally,
and more pointed, even mucronate, the mucro being in some cases nearly as long as the
tail.* The sides of the tail have fewer ribs, and the axis is not so strongly marked out as
in the adult.

In the very neat and characteristic young specimen, PI. III, fig. 15, while the general
character of var. a is preserved, it is in some respects like the var. y, hereafter described.

Surface-ornaments and Tubercles.—The tubercles of the surface are larger in propor-
_ tion in the young specimens. On the axis they are particularly strong. In one of Mr.
Mushen’s specimens (supposed to be a distinct species by De Koninck, and called by him
P. Mushenianus, MS.), the second, fifth, and eighth thorax-rings are ornamented by a pair of
tubercles, the fourth and seventh rings of the tail-axis, and the first and fourth lateral ribs.
Our figured specimen (PI. IT], fig. 15) has the same ornaments, but they are too small to
be shown in the figure. This central double row of tubercles is very conspicuous, and
must surely have some special meaning. On all the young specimens a distinct central
space is marked out by these pairs. On all, the forehead-lobe of the glabella has one
pair wide apart and one pair more approximate. ach of the hinder lobes of the glabella
has a pair (in one of Mr. Mushen’s fossils even the front head-margin has a pair).

Then, as before stated, the second, fifth, and eighth thorax-rings show them—the fourth,
seventh, eighth, and twelfth of the tail, &. And so we get a median line of double

Fies. 11, 12. tubercles, which are only more conspicuous in the
Symmetrical cutaneous glands in the crust of young because in these the tubercles of the general
P. caudatus. ornamented surface are not so large; and con-

sequently these, which do not much increase in
size as the animal grows, lose their importance, so
far as the exterior is concerned.t

But that these tubercles are of real significance
in the structure of the animal is evident enough, if
we examine the fine interior cast figured in PI, III,
fig. 12. I have reproduced this specimen in the

een caauan ams Laed bury. woodcut (fig. 11), and also the exterior of the tuber-
12. Exterior of Malvern specimen. Both in Mus. : : : :
Pract. Gealnns: cular variety (fig. 12), which is the same specimen

* This character is in ordinary cases eventually lost, the mucro not growing in proportion to the
rest ; but occasionally it is preserved, as in var. 5, aculeatus (Pl. III, fig. 18).

+ M. Barrande has specially noted the same fact, with regard to the Sao hirsuta of the Bohemian
basin.

PHACOPS. 53

as that given in Pl. III, fig. 17. It is from Malvern, as is also fig. 16, with the same
prominent ornament.

Here, in this full-grown and very large specimen, it is shown that not only are the
tubercles more than superficial ornaments, for they are distinctly marked out by shallow
oval pits within the crust, but that they are actually far more numerous within, a
pair occurring in fig. 11 on every joint of the axis, It will be observed that they occur in
the adult in precisely the same relative position as ia the young, viz., externally at intervals
on the axis, and on the second, third, fifth, sixth, and seventh lateral ribs, or rather on the
intermediate duplicating furrows of these ribs.

Their position on the side ribs is remarkable. The first pair a, occur on the second rib
about half way out; the next pair closer in to the axis. In like manner those on the fifth
segment 4, are far out, and those on the two succeeding ribs gradually close in. ‘This
regularity of position should be taken into account, as it indicates that there is some
' structural importance in them.*

Var. 6, TUBERCULATO-cAUDATUS. PI. IV, fig. 1.

PHACOPS TUBERCULATO-caUDATUS. Murchison, Sil. System, pl. vii, fig. 84, 1837.
— caupatus. Siluria, 2nd ed., pl. xviii, fig. 1, 1839.

Form broad-ovate. Head decidedly angulated in front. Glabella not so wide as the
cheeks. Tail triangular, pointed, and a little produced.

Comparing this with the ordinary variety, we find that the principal differences reside
in the generally broader form, the length being to the breadth about as 6 to 4, or rather
longer. ‘This excludes the extreme mucro, which is broken off in our largest specimen.

Besides this, the margin of the head is broader, and more sharply distinguished from
the head by a deep marginal furrow. The glabella is somewhat narrower and shorter,
with few large tubercles. he eyes quite as large and conspicuous as in the larger-eyed
forms of the ordinary variety, and which I suppose to be the male (¢), and the front is
more angular; it is produced, but not nearly to the extent of the anterior mucro in
the next species, P. longicaudatus.

The thorax has remarkably large tubercles on the axis, and a central pair on the second
ring, and the pleura on this specimen are tumid at their origin.

The axis of the tail is short and rather flat, and the side lobes have seven or eight very
prominent ribs ; on the fourth, fifth, and sixth of which the remarkable gland-like tubercles
show strongly. The upper one on the first rib is not so prominent. ‘The tail is strongly
margined, and the mucro (broken off) must from its shape have been short and rather
suddenly acuminate.

* They are occasionally even more numerous than here indicated, occurring as tubercles on several of
the lateral segments of the body-rings, as well as on those of the tail (specimen in Mr. Edgell’s collection),
see also Pl. III, fig. 23.

54. SILURIAN TRILOBITES.

These are all the characters that appear to me worthy of note in this fine variety. I
think the large specimen figured by Murchison must belong to it; the tubercles are
arranged in the same fashion. But, the front being broken off, it is not quite certain.
Nor do I know where to find that specimen.

Locality—Wenuock Limustong, Dudley? (Murchison); Lowzr Lupiow, Ledbury
Tunnel (Dr. Grindrod’s cabinet); Dudley Tunnel (Mr. Edgell’s collection).

Var. y, Nexiuis. PI. IV. figs. 3—5.

P. caupatus, Salter, Decade Geol. Sury., ii, pl. i, figs. 10, 11, only.

Form broad-ovate. Length to width as eight and a half to six. Head arched,
obtusely pointed in front, and more than twice as wide as long. Glabella very narrow,
not nearly one third the width of the head. Tail broad-acuminate, not produced, its axis
very narrow.

This neat variety was figured in Decade 2 of the Geol. Survey, but does not seem to
have been specially noticed by any author. It is not very common, except at one locality,
where it is in profusion. At Vinnal Hill, Ludlow, the fine mudstones of the Lower Ludlow
Rock are full of this trilobite.

It is remarkable for the narrow axis to the head, a good deal resembling in this par-
ticular the next species, but differing entirely in the ex-
tremely short general form, which is rounder than even the
common variety, and with scarcely an angular, much less
a mucronate, front. The forehead-lobe is large in pro-
portion to the others; the upper lateral lobe not much
larger than the rest; and the tail, abruptly acuminate,
and very broad for the species, has a very narrow axis, like
the next species. The side-lobes are marked by the usual
seven curved ribs, strongly duplicate.

Our Pl. IV, fig. 4, is the same specimen as that figured in
the Decade 2, pl. i, and shows the true shape of the first
or front ring, bearing the eyes in this subgenus. The
narrow riband-like band in front of the glabella is all on

Fie. 13.

P. caudatus, var. y, newilis, Lower Lud-
low, near Ludlow. Mr. W. Edgel’s the upper surface, not, as in the previous subgenera, mar-

Poids ginal, or beneath the margin.
This last variety brings us very near to the characters of the P. longicaudatus, but has
still the abrupt, not the mucronated, front. And while the axis is very narrow, the general

shape is rounder, instead of longer, than the ordinary forms.

Var. 5, acuLEatus. PI. ITI, fig. 18.

I have before referred to this rather uncommon form (p. 52, note).

PHACOPS. 55

Localities.—|1t has been quoted from Lower Silurian rocks, by myself (the Caradoc
strata of Robeston Wathen and Narberth, in Pembrokeshire, for instance) ; but I do not
know that it really descends below the May Hitt Sanpstonz.]

May Hix Sanpstone (or Upper Llandovery, Murchison), Dingle, Ireland; Barr,
Walsall. Woortnore Limustone and Suats, Malvern; Presteign; Woolhope ; Walsall,
and from the DensicHsHIRE Grits of N. Wales. Werntock Limestone and SHae; the
Malverns; Shropshire; North and South Wales, everywhere ; Westmoreland; Dingle,
&c. Lowzr Lupnow and Aymzsrry Limestone of Shropshire and Herefordshire ;
of Dudley Tunnel; of Malvern. Uprzr Luptow, Ludlow; rare in this formation
(R. Lightbody).

The above are localities in general for the common variety. Var. 6 is found in Wen-
Lock Limzstons (Murchison), and our figured specimen from Lowrr Lupiow, Ledbury
tunnel, in Dr. Grindrod’s cabinet. Var. y is only known as yet in Lowzr LupLow
rocks, and specially at Vinnal Hill, Ludlow (Mus. Pract. Geol.) ; also at Newton, in the
same neighbourhood (Mr. Edgell’s cabinet). Var. 3 is from Dudley.

Puac. (OpontocHILe) Loneicaupatus, Murch. PI. III, figs. 19 —28.

TRILOBITE WITH CAUDAL PROCESS, Parkinson. Organie Remains, vol. ii, t. xvii, fig.
Fuel fos al
ASAPHUS LONGICAUDATUS, Murchison. Silur. Syst., pl. xiv, figs. 11—14, 1837.
— — Milne-Edwards. Crustaces, iii, 308, 1840.
PHACOPS LONGICAUDATUS, Emmerich, Goldfuss, §c. Loc. cit., 1845, 1846.
— mucronatus, Burmeister. Org. Tril., t. iv, fig. 9 (exclude synonyms), 1843,
and ed. 2 (Ray ed., 1846).
—- cAUDATUS, B LoNGIcAUDATUS, Salter. Decades Geol. Survey, ii, pl. i, figs.
13, 14.
Var. a, aRMIGER. PI. III, figs. 19—21 (P. longicaudatus of authors).
Var. 8, GrinpRopianus. PI. III, figs. 22—28, new variety.

P. (Odontoch.) medius, 2—3-pollicaris, ovatus elongatus subconvexus, capite lato, fronte
mucronato. Oculi maximi. Pleure sulcate recurve, fulcro ad dimidium. Cauda trigona
longimucronata ; axe 15—16-annulato, ad apicem haud eminente ; costis lateralibus 7 arcu-
atis, duplicatis, ad marginem levem abrupte terminatis, recurvis.

Distinguished easily at a glance from the more common P. caudatus by the greatly
elongate tail, but much less distinct when closely examined, since the general habit and
even the minute structure is similar to that of the Wenlock species.

In all the specimens I have seen (and there are few perfect ones extant of the long-
tailed species) the following differences are observable :—Ist. The axis is invariably
narrower, not one third the width of the head, always quite as much so as in the P.
caudatus, var. nexilis, which differs from the other varieties in this particular, and yet has
less trace of a mucronate front than any of them. 2nd. The abrupt mucro (not mere
angulation) to the front. 3rd. ‘The smaller tail, with more arched furrows. 4th. The

56 SILURIAN TRILOBITES.

ereat terminal mucro, always equal to the length of the tail itself, and often half as
long again.

There is evidently, however, a nearer connection between the var. 8. (G@rindrodianus)
from Malvern, and the var. y of the last species. But while in this variety 8, which comes
nearest to P. caudatus, the mucrones of the head and tail are shortened, the narrow axis
still easily distinguishes it from the varieties of that species ; and the variety y, zewz/is of the P.
caudatus, which has really a narrow axis, has nearly lost all trace of the processes, and has
scarcely a mucro at all. It is not difficult, therefore, to distinguish the two species.

Description.—Full-grown specimens must have been fully six inches long, including
the tail. The form is elongate, and less convex than in P. caudatus. In both varieties
the head is less than twice as wide as its length, but is still transverse in shape, its
glabella scarce one third the whole width. The glabella at its front part is parallel-sided.
Forehead-lobe transverse-oval, well separated from the side-lobes, which are tolerably
equal,—the upper one not greatly largest. Eyes large, pyramidal, and placed very near
the glabella, so as almost to touch it in front, and strongly curved,* reaching below to
the neck-furrow, and often overhanging it.

The axis of the body and tail narrow in proportion to the sides, sometimes not one
fourth the width in the body-rings, and barely one fifth im the tail. The surface of the
body-rings is tubercular. Hinder pleuree much bent back. Fulcrum at about one half.
Pleural groove shallow, ending in a point beyond the fulcrum. ‘Tail small in proportion,
with few (5—7) side-furrows, much curved and strongly interlined. Mucro abrupt,
linear, as long or longer than the rest of the tail. ‘The gland-like tubercles sometimes
present, but often inconspicuous throughout.

The above characters are common to the two following varieties.

Var. a, ARMIGER: PI. II, figs. 19—21.

Fig. 14. Head, including the strong front mucro, much more than
half as long as wide. Glabella not one third the width of the
head. Marginal furrows strong. Head-spines as long as the
cheek. Mucro of tail much larger than the rest of the tail; side-
furrows 7,

I figure a remarkable specimen from Mr. Edgell’s cabinet, in
which the spine is considerably more than twice the length of the
axis, and is expanded at the tip, more than is shown in our woodcut.

One specimen of Dr. Grindrod’s shows clearly the passage
from this form to the next variety, P. Grindrodianus, having the
mucro quite as long as usual, but having only five lateral ribs, and
tubercles on the axis and sides. Usually P. longicaudatus, var.
armiger, Shows seven lateral ribs, and has no distinct tubercles.

* Much more so than in P. caudatus.

PHACOPS. 57

Localities —Var. a, Wootnore Limestone, Presteign; Wrntock SHALE of Cheney
Longville and Burrington, Shropshire (abundant) ; Usk, Monmouthshire ; also Carmarthen-
shire, Brecon; and Marloes Bay, Pembrokeshire, more rarely. It is quoted also from
Wentock Limxstonn, Malvern, in the Survey lists.

Var. 2, Grinpropianus.- Pl. III, figs. 2—28.

Head, including the short front mucro, somewhat more than half as long as wide.
Glabella, at its widest, not more than one third the width af the head. Forehead-lobe
prominent. Tubercles on head, body, and tail, conspicuous. ‘Tail with few (5—6), side-
furrows, and about ten axal rings; the spme not more than equal to the rest of the tail.

This variety, of which we fortunately can examine a fine suite of specimens, differs
from the typical form in points which do not affect the specific characters given above.
It is only less extravagantly armed,—the front, rear, and side-spines being all shorter. ‘The
side-spines reach to the seventh segment. ‘The surface shows the tubercles characteristic
of the young,—in the adult state; both on the forehead-lobes and the lower lobes of the
glabella, on the axis of the body,’ and on the fourth and eighth segment of the axis of the
tail. The gland-like tubercles on the fourth side-pleurz are not always conspicuous. —

The mucro is shorter, seldom equalling the tail itself in length. The side-ribs are
five, strongly duplicate to the very end, and the margin very narrow.

Docality.—Var. P, Wentock Suaz. It is known only at Malvern Tunnel and Dudley.

Puacors Wravent, Salter. PI. III, figs. 1—3; Pl. IV, figs. 6—9.

Puacors Wzavurt, Salter. Decades Geol. Surv., ii, art. 1, p. 7, pl. i, fig. 16.
— — Id. Morris’s Catal., 2nd, ed., p. 114, 1854.

P. levis, capite quam in P. cand. nisi trigono lobisque glabelle tumidioribus. Cauda
triangularis, fere equilatera, multicostata, convexa, apice acuto brevimucronato ; avi 18—16-
annulato, costis lateralibus 10 —12 simplicibus, vie curvis, ad marginem angustum abrupte
terminatis.

We know but little yet of this fossil. It is fragmen-
tary as yet ; and though I believe the specimens here figured
all belong to one species, I would prefer to keep the name
for the fossil of the May Hill Sandstone.

The head is very imperfect ; what there is of it strongly
resembles P. caudatus, except that the lobes are ‘a little
more tumid; the forehead-lobe is more strongly marked

Fre. 15.

Head of P. Weaveri ? Canada.”

* It seems that when the tubercles exist on the sides of the axis, they are not present towards the
centre, and vice versd. But it is not every segment which has the tubercles at all.
» I have good reason to believe this Canadian species, brought by Sir W. Logan from Ile Perce,

8

58 SILURIAN TRILOBITES.

off, and somewhat overhanging the side-lobes. The eye does not reach the neck-

furrow.
The tail is broad-triangular, wider than long; the sides a little convex; the apex

short-mucronate ; the axis narrow, conical, ribbed by about sixteen rings; the sides very
convex, with nine to ten arched simple ribs, scarcely at all interlined; the margin narrow,
smooth.

Locality.—May Hutu Sanpstong, “ Long’s Quarry, Damory Bridge, Charfield, and
Woodford Green, Tortworth ;” (Decade 2, Geol. Surv., p. 7).

Figs. 8, 9, show a variety with ribs slightly duplicated on the interior cast, but with a
short mucro. It is from Marloes Bay, Pembrokeshire (Mus. Pract. Geology).

Larger form of the species.

Pl. TI, figs. 2, 3.

The large caudal shields here figured clearly belong to a species distinct from P. caudatus.
They are one and a half inch long, and probably reached two inches in width when
perfect. The general form agrees well with that above described, and it has the numerous,
‘slightly curved ribs, scarcely duplicated at all, and with the interstices deeply concave.
They are very little bent at the extremities. Our fig. 2 is better in this respect than
fig. 8. The margin is equal and narrow all round.

P. imbricatulus of Angelin has ten dichotomous side-ribs, and a very distinct margin ;
else it is not unlike our species.

Locality.—Luptow Rocks? Horseshoe Farm, Tortworth. It is possible there is a
boss of May Hitt Sanpstonz at this place.

Section—Crypuxus (p. 15).

This subgenus alone would decide against the folly of classifying Trilobites by such
a character as the pattern of the tail. All the species known in Europe or North America
are allied to Odontochile, and follow naturally that subgenus. But in the southern
hemisphere we have compact forms allied to Acasée, which have the tail spinose.

Gaspé, Lower Canada, to be identical with ours. The tail is a little more mucronate. The head agrees
nearly with our fragments, and will at all events give collectors a good idea of the probable shape. It is
remarkably triangular, even for this subgenus.

PHACOPS. 59

Puac. (CrypHaus) punctatus, Steininger? PI. I, figs. 17—19.

OLENUS PUNCTATUS, Steininger. Mém. de Soc. Géol. Fr., i, p. 356, vol. i. pl. 22, 1833.
— — Emmerich. Dissertation, p. 55, 1839.
ASAPHUS ARACHNOIDES, Goldfuss. Leonhard und Bronn’s Neues Jahrbuch, p. 561, tab.
v, fig. 3, 1843.
CALYMENE — Honinghaus, pamphlet, Crefeld, 1835.
PLEURACANTHUS ARACHNOIDES, Milne-Edwards, Crust., iii, p. 329, 1840.
— punctatus, Roemer. Rheinisch Uebergangs., p. 82, 1844.

PHACOPS ARACHNOIDES, Burmeister, Org. Trilob., Ist ed., 1843; 2d ed., p. 96,
1846.

— waciniatus, Salter, in Morris’s Catalogue, 2nd ed., p. 113, 1854 (not of
Roemer).

Phacops ( Crypheus) “ scuto capitis in medio marginis antici acuto, angulis posticis valde
productis ; limbo scuti caudalis decies spinosa.’—Burm., |. c.

The only notices I can find of this as a British species are by myself—first, in the
Decades of the Survey, No. 2, under the description of P. caudatus, p. 8, where it is
referred to P. arachnoides of Goldfuss; and afterwards in Morris’s Catalogue, 2nd ed.,
1854, where it is referred, I think wrongly, to P.,daciniatus, Roem. The fragments
known were so very obscure, that enough could only be seen to make it certain we had
one of the species of this remarkable group, in which the tail-margin has undergone its
fullest expansion.

In order to give the English collector a notion of what
he may expect to find, I have drawn a perfect specimen from
Germany, nearly following Burmeister. And, after comparing
with the best specimens at my command, I think the first refer-
ence was right, and that the British species is the well-known,
but still rarely perfect, Olenus punctatus of Steininger, a name
which should have been retained for this fossil, as Stein-
inger’s figure is quite recognizable.

I purposely avoid describing the British fragments, as the
inspection of the plate will show that they only indicate a
species with narrow, long glabella, with tolerably equal lobes,
a granulated surface, a pointed front to the head (not pro-
duced, however, as in the foreign specimens), and longer head-
spines than in the German specimens. ‘The eyes appear to be
not quite so large.

Phacops ( Crypheus) punctatus,Stein.,
from Burmeister’s work.

‘The tail shows ten spines, which are rather shorter, less convergent, and more radiating
than Eifel specimens warrant.’ But they are narrow, not broad, fin-like plates, as in
P. laciniatus, and longer, too, in proportion than in that species ; the glabella, too, is nar-

! Goldfuss’s figure is more faithful than Prof. Burmeister’s.

60 SILURIAN TRILOBITES.

rower and more pointed, and the lobes less crowded. It need not be compared with
P. stellifer, Burm., as that species has eleven broadish spines.

We must wait a little for more perfect information.’ It is certain that a very beautiful
Trilobite is yet to be found in Cornwall and South Devon, and collectors should look care-
fully for it. Pied

Locality —Mivp. and Lowzr Devonian. Torquay, South Devon; Slates of Lis-
keard, Cornwall (Coll. Mr. Pengelly and Mus. P. Geology).

Famity—CHEIRURID A.

A group whose limits are not yet fully defined, if, as I suppose, it should include all
the forms cited below. The Cheiruride proper have really more of the characters of
the Phacopide than appears at first sight, for these loosely built Trilobites have the eyes
reticulate externally, though on a smaller scale than Pdacops, and the facial suture ends
upon the exterior, not the posterior, margin. The normal number of body-rings is eleven.
With these pomts of resemblance, important as they are, the analogy ceases, for the
short, oblique furrow and free ends of the nodular pleuree give a very marked aspect ;
and the tail is of few joints, and the ends of their pleure are also free.

The genera thus included are Cheirurus proper and its subgenera, and Spherexochus,
with Amphion and Placoparia. Staurocephalus and Deiphon must follow these.

But the other group, Hucrinurus, Cybele, Cromus, Zethus, &c., though they agree in
the marked position of the facial suture, have so many differences of habit that I am
doubtful if they should not form a distinct family. The long prominent eyes may or may
not be granulated; we have no evidence of it. But there is a strong resemblance to the
family of the Acidaspidee, which follows next, and I shall reserve the description of both
of these groups till all the available material is collected.

CHEIRURUS, Beyrich, 1845.

Head strongly trilobed ; glabella with three lateral lobes, the basal ones circumscribed ;
eyes facetted minutely ; facial suture ending on the external margin [under side of head
with a transverse rostral shield, Barrande]. Cheeks generally scrobiculate. Labrum
inflated, oblong, truncate, with a pair of furrows and small lateral auricles.’ Thorax of
ten, eleven, or twelve joints, variously sculptured in the different subgenera.

1 Goldfuss’s introductory remark to his ‘Essay on Trilobites’ is still very applicable to the group, if
not quite germane to the subject., I beg to refer the curious reader to it (‘Neues Jahrb.,’ 1843,
p. 537). Ad ;

® There is also a blind Devonian genus of this group, from Africa, in Lower Devonian, —Typhloniscus.

* See Plate VI, figs. 12, 13. We want a term, and I propose the above for these lateral portions of the
labrum, very distinct in Chezrurus, Lichas, &e.' |

CHEIRURUS. 61

Subgenera.

~

Crotalocephalus, Cheirurus, Eccoptochile, Actinopeltis ; and most probably Spherewo-
chus, ought to be added. It is simply convenient to keep this last as a distinct genus.

Subgenus—CrortaLocerHaus, Salter, 1853.

Glabella oblong, broadest in front, with furrows continuous across. Body-rings 11,
nodular.
Devonian. Upper Silurian.

Subgenus—CuEIRURUS, Auctorum.

Glabella broadest in front, with furrows all distinct, but not meeting across. Body-
rings 11, nodular.
Upper and Lower Silurian.

Subgenus—Wccorrocuiiy, Corda, 1847.

Glabella ovoid, not much inflated, with long furrows. SBody-rings 12, grooved
imperfectly, not nodular.
Upper Cambrian? Lower Silurian.

Subgenus—ActiINoPELTIs, Corda, 1847.

Glabella ovoid, often much inflated, and with the anterior furrows nearly obsolete.
Body-rings 10, grooved imperfectly, subcylindrical, not nodular.

Many of these lead directly to the genus Spherewochus, which has only the characters
of Actinopeltis in an exaggerated form. Its labrum is like that of Actinopeliis, and its
pleuree are subcylindrical, and the body-rings 11.

Subgenus—CROTALOCEPHALUS.
Cu. (CRoTALOCEPHALUS) ARTICULATUS, Miinst.? Pl. VI, figs. 7, 8.

CALYMENE ARTICULATA, Miinster. Beitréige, vol. ili, pl. v, fig. 7, 1840.

-— — Srernperer, Phillips (not Minster nor Boeck). Pai. Foss., fig. 247, 1841.
CALYMENE _— Burmeister. Organ. Trilob., 2nd ed., p. 116, 1846.
CHEIRURUS ARTICULATUS, Salter. Decade Geol. Surv. 7+ plot, att. & p- 10; 1853.

— —~ Id. Morris’s Catal., 2nd ed., p. 103, 1854.

62 SILURIAN TRILOBITES.

C. capite 14 unciam lato, longo, convexissimo, articulato. Glabella subcylindrica, anticé
latior, lobo frontali semicirculari, supremo lineart, secundo subtriangulari, basalibus trigonis
subplanis longis, feré medium glabelle attingentibus, cervicali triangulato lato. Gene
declives convexa, profundé scripte et marginate, spinis divergentibus brevibus. Oculi
haud ad glabellam appositi, ad lobum medianum retracti. Junior cum senioribus forma
conventt.

When described for the Decades of the Survey, we possessed but one or two imperfect
heads. Now we have excellent specimens from Mr. Pengelly’s cabinet. ‘These show the
true shape of the glabella and the fixed—but not the free—cheeks. Lest there should be a
mistake, I have only given the characters from the British specimens, which differ from
Miinster’s figure in having a shorter glabella, with the terminal lobe especially not so long,
(Miinster’s figure has it almost circular, which is not likely), and narrower cheeks ; and
that author also describes his species as having great wings, or free cheeks, like those of his
C. propinqua. If his figures were quite trustworthy,’ our species must be distinct,
and I should, in that case, propose the term C. Pengellyi for this fine Devonian
fossil.

Our species has the head eleven lines long, by one and a half inch broad, the glabella
occupying the whole length, and regularly tapering from a breadth of eight lines in
front to six at the base. ‘The forehead-lobe is semicircular, and: occupies just as much
length as the remaining lobes, excluding the broad, subtriangular neck-segment. The
middle and upper lobes are separated by complete, deep, transverse furrows, and are of
equal width, the upper pair forming a transverse linear band, the middle pair also trans-
verse, but rudely triangular where they abut on the truly triangular basal lobes. ‘These
reach far across, and are separated by a depressed space barely equal to half the width of
one of the lobes. The basal lobes are less tumid than the rest, the upper lobe more so
than the middle one, and the forehead-lobe more tumid than any. ‘These proportions are
maintained in young specimens (see fig. 8). The surface of the glabella is coarsely
tubercular. .

The cheeks, separated by deep axal furrows, are convex, rather steeply declining, their
full width equal to that of the glabella at its base, and the position of the eye-line is such
that the free cheek is not above one third the length of the head (in Miinster’s figure it
is much more), with a strong thickened margin and marginal furrow, within which the
cheek is deeply punctured, and appears tubercular ; the head-spines diverge, and are short
and narrow.

The profile-view (fig. 7, 4) gives a good idea of the convexity of the head.

1 Count Minster gives us good reason to distrust his accuracy, for he figures the lower glabella-
furrows as continuous across, instead of bending down to join the triangular basal lobes. This is im-
possible. He has represented his so-called C. Sternbergii, and C. propinqua, which are probably but one
species, as having these broad wings, but there is an appearance of error about all his figures.

CHEIRURUS. 63

The specimens figured are destitute of body and tail; perhaps our Devonian friends

can supply better examples.
Locality—MivviE Devon1an Luwestone of Lammaton, Torquay (Mr. Pengelly’s and

Mr. Vicary’s cabinets, Mus. Pract. Geology).

Currgurus Brmucronatus, Murch. Pl. V, figs. 1—5; Pl. VI, figs. 9—18.

PAaRADOXIDES BIMUCRONATUS, Murchison. Sil. System, pl. xiv, figs. 8, 9, 1837.
—_ — Milne-Edwards. Crust., iii, p. 343, 1840.
CALYMENE speciosa, Hisinger. Leth. Suecica, 2nd suppl., t. xxxix, fig. 2, 1840 (not

of Dalman).
ARGES BIMUCRONATUS, Goldfuss. Neues Jahrbuch., p. 544, 1843.
CHEIRURUS — Beyrich. Ueber einige Bolimische Tril., pp. 18, 19, 1845.

— INSIGNIS, Td. Ibid., p. 12, fig. I, 1.
a = Barrande. Notice Préliminaire, p. 49. 1846.
— _— Id. Syst. Sil. de Bohéme, pl. xli, figs. 1—13 (optime),

1852.
— SPECIOSUS, Salter. Memoirs Geol. Surv., vol. ii, pt. 1, pl. vii, figs. 4, 5, 6.

Crraurus Witiiamsu, M‘Coy. Ann. and Mag. Nat. Hist., p. 408, 1849.
_— — Id. Pal. Foss. Woodw. Mus., pl. i, F, fig. 13, 1851.

CHEIRURUS BIMUCRONATUS, Salter. Decade 7, pl. ii, 1853.

C. (Chetrurus) grandis, 8—10- uncialis. Glabella superné latior, sulco frontali et
oculari obliquis prope medium glabelle terminatis ; lobis inferis trigonis (atate rotundioribus)
sejunctis. Gene glabellé angustiores, oculis medianis, spinis posticis parallelis. Thorax
pleuris trituberculatis. Cauda parvula, utringue pleuris tribus subequalibus ad basin
brevisulcatis, apicibus robustis in etate arcuatis, sepe mucrone centrali brevt.

Few Trilobites are more common than this in the border-counties of England and
Wales, and few are so seldom found in a perfect state. We owe the beautiful specimens
here figured to the care and diligence of the Dudley collectors, who, following the good
example long ago set by Mr. John Gray, are patiently developing the shale specimens
which used to be neglected. It is found that the shale matrix preserves the fossils best.
Mr. Gray is still at work, and is the master of this art. Our good friend, Mr. C. Ket-
Jey, of Smethwick, is hardly less skilful, and we are much indebted to both these gentle-
men. Mr. Allport, of Birmmgham, Mr. E. Hollier, jun., of Dudley, and others, have
lent us choice materials. We now know the whole of this species, which, when
first described, was one of the most obscure of all our Trilobites. It has a wide
range, from Caradoc to Ludlow Rocks inclusive. It is found in North Europe,
but not in America; and it is an excellent type of the genus Cheirwrus. Neither
unduly inflated in the head, nor greatly depressed, as in some of the Lower Silu-
rian species, it is a typical form, with glabella-furrows running partly and not com-

64 SILURIAN TRILOBITES.

pletely across, and with an oblong shape of glabella, the aberrant species -having it oval,
and some even globular, as we shall see further on.

It was first described as a Paradoxides by Murchison, who only knew the caudal
portion ; the head was figured about the same time by Hisinger, under the name C. speciosa
of Dalman, an identification which there is now every reason to doubt, as the synonymy
has been cleared up by the labours of Angelin, to whom we should be still more indebted
were his descriptions less brief. As I have endeavoured in the Decades of the Survey’ to
show the history of the species, I need not go over all that ground again, and I retain the
name C. dimucronatus, as already well known and adopted by several authors ; indeed, it
appears to have been the earliest.

Var. a, BiMucRonatus. PI.‘ VI. figs. 15,16, 17. Cauda mucronibus posticis angustis,
centrali nullo. Decade 7; Geol. Survey, pl. ui, figs. 4, 5, 6.

Var. 6, centratis. Pl. VI, figs. 9, 10, 11, 12, 18, 14,18. Cauda mucronibus sub-
equalibus, centrali brevi distincto. Mem. Geol. Surv., |. ¢., fig.

7; Decade 7, pl. ui, fig. 16.

The following is the description given in the Decade, with some modifications, and
the omission of details.

One of the larger Trilobites; it measures occasionally nine (not twelve) inches, but
probably not more. ‘The more perfect specimens found at Dudley are not above two or
three inches long, those from Malvern are larger, and those from the Caradoc limestones
of South Wales and Ireland the largest of all. Length to breadth as 3 to 2; the
head occupies fully one third the length, and is a little broader than the body. General
form moderately convex and oblong, but narrowed suddenly towards the posterior end ;
the sides of the thorax and tail deeply serrated by the projecting ends of the segments.
The animal is sometimes found half coiled up; the pointed ends of the pleure closing
together, and overlapping each other.

Head rather more than a semicircle, the obtuse front Hescints ; glabella gently
convex, equal in breadth at the base to the cheeks, above considerably broader, marked
with three strong furrows on each side, besides the neck-furrow, the lowest being directed
obliquely downwards, and joining the neck-furrow before reaching the middle; it thus
encloses a spherical triangle as a basal lobe. In older ‘specimens this lobe is somewhat
squarer, and the furrow more curved. The other furrows curve but little downward, and
are variable in length, but usually extend more than one third across the glabella on each
side. The furrows on the glabella, as well as the axal furrows, are sharp, but not broad
or deep exteriorly, although they are so on casts of the inner surface. Forehead-lobe of

1 Decade 7, ‘Geol. Surv.,’ plate ii.

CHEIRURUS. 65

moderate size, half as long as the entire glabella, and on the sides overhanging the other
lobes ; in front it is somewhat produced, and occupies all the margin. The glabella is
neither gibbous nor depressed, a line taken from the front edge to the neck-furrow pre-
senting a regular and gentle convexity. Cheeks subtriangular, not so wide as long, with
a broadish margin distinctly separated by a furrow, which meets the strong, straight neck-
furrow at the posterior angles; these angles are spinous, the spine short and directed
backwards, The eye is placed more than half way up the cheek, and not close to the
glabella; it is opposite the middle furrow, and is rather small, supported by a raised rim
below ; the eyelid is narrow and indented, the lentiferous surface very convex, supine, and
covered with minute, closely set, convex facets, with no spaces between them. In
some specimens each facet has a minute pit upon it, but this is due to wear; the lenses
being regularly convex when perfect. These are figured in the Survey Decades. Above
the eye the facial suture takes a vertical course, and cuts the margin exactly where the axal
furrow ends on it; below the eye it turns directly outwards to the smooth border, which
it cuts considerably in advance of the posterior angle, and in an oblique direction, so that
it. reaches further back on the lower side than on the upper.

We do not know the course of the suture in front; it is probably direct across,
beneath the front margin, and Barrande describes a rostral shield on the under surface.
The surface of the glabella is sparsely covered with small granules (fig. 9), the cheeks are
largely scrobiculate, and the wings or free cheeks have their border smooth, and only
scabrous on its outer edge ; they are sometimes dilated a little in advance of the facial suture.
Labrum (Pl. VI, figs. 12, 13) large, ovate, oblong, very convex; its length generally one
fourth more than the width, but in appearance often more ; broadest near the strongly arched
base of insertion, from which the central convexity rises immediately, and reaches nearly to
the tip. A rather deep furrow surrounds the central portion, and separates it clearly from
the more or less tumid margin. The furrow becomes deepest near the rounded shoulder,
which we have called the ‘auricle,’ followed by a deep notch, above which the ascending
processes (a, a) take their origin. The apex of the labrum is truncate, the corners angular,
vr even mucronate. Besides the distinct sulcus, which separates the border all round,
there is a short oblique furrow higher up on each side. ‘The whole surface of the labrum is
closely scabrous (Pl. V, fig. 5) ; the convex portion has, besides, scattered, larger granules.
The organ is hollow when viewed from the inner side (PI. VI, fig. 13), and the structure there
observable is such as has been described by Barrande.'| There are two ascending pro-

1 M. Barrande, ‘Neues Jahrbuch.,’ 1847, p. 389, has given a full description of the ‘hypostome’
of Cheirurus. He describes the ascending processes a, a (Fliigel), as bent upwards at right angles to the
surface of the organ, and uniting with the upper crust along the line of the dorsal or axal furrow, with
a broad base of attachment, reaching from the upper to the middle glabella-furrow. In Phacops it has
nearly the same position. He also describes a second organ, of the same size and shape, but less convex
in all its parts, lying immediately behind the hypostome, between it and the upper crust of the head.
This organ he calls ‘ epistoma ;”’

9

and he has seen it both in Cheir. insignis and a species of Phacops. It has

66 SILURIAN TRILOBITES.

cesses (a, a) rising from the ends of the basal or front margin, and directed obliquely
backwards ; and on the sides (4, 4) are two inflated, broadly triangular portions characteristic
of the genus. ‘These triangular curved plates give the appearance of thickness on viewing
the organ from the side (fig. 13c); but the general surface on the inner side is concave,
answering to the great convexity of the outer side.

Thorax much longer than the head, but narrower, and for most part of it parallel-
sided, of eleven gently convex rings, which are very minutely scabrous; the axis is
narrower than the glabella, of nearly equal width all the way down, but scarcely so wide
as the pleura. ‘These are linear, and directed straight outwards for two thirds their
length, then curved a little backwards, and tapering to a sharp point. The fulcrum,
placed at about one third, is of singular structure; a small, semi-oval piece (fig. 14, a) is
attached to the posterior edge of each pleura; and against this piece abuts a similar
tubercle (4), placed on the front edge of each; and the two pieces, forming together a
narrow oval tubercle, are insulated by a deep sulcus from the body of the pleura, which
is also constricted and furrowed across at this point so as to have the outer and pointed
portion (c) quite distinctly separated from the small inner one. ‘The latter is very
strongly divided into two tumid lobes by a short oblique sulcus, and just beyond the con-
striction the outer portion rises into a stout boss, giving the tri-tuberculate form cha-
racteristic of the genus, The line of the fulcral-points is parallel to the axis for its whole
length, and the constriction beneath them, though not very marked on the upper crust
(fig. 14), produces a longitudinal ridge on the under surface and a corresponding strong
furrow in casts (fig. 14d).

‘Tail, in all our specimens, very much narrower than the body, with three strong
spinous lateral lobes on each side directed backwards, the outer ones a little di-
vergent and longest; all extend equally backwards; the tail is therefore truncate, but
exclusive of the spines, it is broad-triangular, following somewhat the shape of the axis;
it is marked on each side by four short, deep puncta or furrows, which do not run to the
margin, even in young individuals. The axis is convex and short-conical, of three distinct
ribs, and a small terminal piece, the last very obscurely indicated ; there is, between the lowest
spines in the ordinary Wenlock forms, sometimes a blunt, sometimes an acute mucro, and
occasionally none at all.

Variations.—The following have been observed :—In a Dudley specimen the front or
forehead-lobe occupies much more than half the length of the glabella, the side lobes
being, therefore, more crowded. In another Dudley specimen a large tubercle occurs in
the middle of the forehead-lobe. In some individuals the glabella widens more above ; in
others it is nearly parallel-sided, and the lateral furrows vary in length. The head-spines
occasionally reach the third thorax-segment. The margin of the cheek in one specimen
is notched at the facial suture. The axis of the thorax is sometimes, though rarely,

never yet occurred to our observation, nor apparently to others. Yet it seems not unlikely that two
plates, an upper and under lip, should form the channel to the mouth.

CHEIRURUS. 67

as wide as the pleurae. The most important variations occur in the tail. In figs. 10, 15,
we have represented the spines as all directed backwards, and the two central ones closely
approximate ; they are so in the large Ledbury specimen figured in the ‘Silurian System,’
where, too, they are shorter than the outer spines. In others they are a little space apart.
In a Lower Silurian specimen we have seen a small tubercle appear between, and in our
var. £, figs. 9, 18, a decided, though short, mucro protrudes. Lastly, as a monstrous variety
from the Silurian rocks of Kildare (we have reason to think it of the same species), we have
one with a wider interval and a bifid mucro. In old specimens, as well as in var. g, the spines
diverge much more than in most of those here figured. Perhaps some of these variations
are due to sex. It is observable in some specimens (fig. 9) that a double row of tubercles,
like those observed in Phacops (p. 52), occurs down the axis of the thorax.

Affinities —Among a host of kindred species in this prolific genus, the only Bohemian
fossil with which it is really necessary to compare this is the C. cnsignis, Beyrich.
Barrande’s figures leave nothing to desire, and I confess I know not how to separate the
two. (C. insignis has a somewhat different habit, and the central tail-spine is more
prominently developed. But except this, and having a less overhanging glabella, I do not
know how to distinguish the Bohemian form, nor can my friend Mr. H. Woodward see
any differences of value.

With the C. speciosus, as figured by Hisinger, I believe ours to be identical. C4.
(Calymene) ornatus of Dalman has the head very like, as we learn from Angelin’s figure ;
but the upper glabella-lobe of that species is not nearly so long as ours, nor is it wide
enough above. The British species is variable enough ; but it is, for all that, distinct from
those above quoted.

Localities —Carapoc to LupLow Rocks ; Carapoc, South Wales, near Haverfordwest,
abundant ; North Wales; Kildare, Ireland. Luanpovery Rocks of Goleugoed, near Llan-
dovery, South Wales; Mullock, Ayrshire; Galway, &c. May Hi1u Sanpstons, Nor-
bury ; (PI. V, fig. 3). Also in the purple Shales, Onny River, Shropshire. Woo.nors
Liuestong, Presteign ; Malvern. Wenuiock Limestone and SHALE, everywhere. Wenlock
strata of South Wales, and West of Ireland. Aymersrry Limestone, Downton Castle,
Ludlow. Also in Sweden and Bohemia (Upper Silurian).

Cu. (ACTINOPELTIS) JuvENIS, Salter. PI. V, figs. 9—12.

CHEIRURUS JUVENIS, Salter. Memoirs Geol. Survey, vol. ii, pt. 1, pl. vii, figs. 1—3,
(exclude 3, 6, which belongs to the next species), 1853.
— CLAVIFRONS, Id. Ibid., Errata, p. viii.
— a Id., in Appendix Synops. Paleeoz. Fossils of Woodw. Mus.,
t. iF, fig. 11; t. ic, fig. 9, 1851.
Ceravrus CLAVIFRONS, M‘Coy. Ibid., p. 154 (but not t. 1 F, fig. 12, for which see
Spherexochus boops),

This rather common fossil has been bandied about, in search of a godfather, for some

68 SILURIAN TRILOBITES.

time, and, having found a resting-place in the verdict of Prof. M‘Coy and myself, must be
again disturbed ; for there seems little doubt that, whatever Dalman’s C. clavifrons may be,
it is not a species with a narrow front to the glabella. Prof. Angelin’s figures, quoted under
the next species, give us a clue through the uncertainty which has hung over this species ;
but unfortunately his scanty description does not enable us to clear it up. Prof. Sars
and Dr. Boeck described first one and then a different Trilobite under this name; and
neither was the true species of Dalman, who, as if to justify all the confusion that has
since resulted, placed two distinct species together in the Stockholm Museum under the
name C. clavifrons, one of which has the glabella narrow in front and _ parallel-sided, and
could not have suggested the term (Angelin, ‘Pal. Suec.,’ t. xxxvin, fig. 9); to this one
Prof. Angelin has, however, applied the name; the other, with a subclavate glabella and
minute eyes (pl. xxxviii, fig. 10, which does deserve the name C. clavifrons, and to which
Prof. Angelin attaches that synonym and the note as to Dalman’s authority), he by some
strange fatality calls a new species, Cyrtometopus affinis |

We shall never have done with the confusion of these forms, unless we restrict Dalman’s
name to the species called C. afinis by Angelin. In that case I believe our next species
will have to forego its baptismal privileges. But pending the settlement of this (and the
difficulty is increased tenfold in a genus like Cheirurus, full of closely related and very
similar forms), I shall revert to my old name, Ch. juvenis, which sufficiently expresses the
smooth contour of the head. It is certainly distinct from all the Swedish forms, though
resembling all which have figured under the above name; and the synonyms given above
may, I think, be trusted; all the specimens have been seen by myself.

C. juvenis is a large trilobite for this section of the genus, and must have measured
three inches in length. It has not yet occurred perfect ; but the glabella is rather common,
both in Wales and Ireland. It is an ovate and very convex mass, equally attenuate at
each end, gibbous along the median line, and regularly convex along a line taken from
front to back, not. projecting near the base, and scarcely overhanging the front. The
furrows are three on each side, the basal one strong, and completely circumscribing the
oval basal lobe; the middle and upper ones gently curved, and equally remote from each
other and the basal lobe. The front furrows are placed very forward.

The cheeks are steeply curved down, but not abruptly so; the neck-furrow strong, the
surface scrobiculate, the eye placed behind the middle furrow, and therefore about half
way up the cheek. We have not the free cheeks, but they probably showed a narrower
margin than in the following species. The glabella is covered equally with granules and
tubercles. Head-spines short.

Tail with very unequal lobes, the outer ones by far the largest, and produced into stout,
slightly divergent spines, with a broad subquadrate base, marked by a short, deep, pleural
groove. ‘I'he two inner pairs are rapidly smaller, the last quite minute. But these vary
in length and obtuseness. In our figured specimen they are not longer than the broad,
long, conical axis of four joints, which intrudes its last joint between the short terminal

CHEIRURUS. 69

mucrones, and which is, at its upper portion, as broad as its pleure, which have a wide,
straight base of articulation. ‘The articular portion of the axis is also large. -

Fig. 9 represents the outer granulated surface of the glabella. The furrows are not so
deep as in the cast (fig. 10) ; but the cheeks are equally scrobiculate, and more strongly so
than in our next species.

Comparing with other species, we find, first, that the original C. clavifrons of Dalman
is, according to Angelin’s figure, a species with a narrow glabella, somewhat gibbous at
the base, and with very broad and deep-fixed cheeks, with strong head-spines. ‘The basal
lobes of the glabella are promment and circular. The C. afinis of Angelin, which was
placed by Dalman with this, and seems by its shape to have been the actual species
intended by him, has a subclavate glabella, and also very forward, minute eyes. The
glabella of C. tumidus, Ang., a good deal resembles the large corresponding part in our
species ; but it differs essentially in not having the basal furrows complete, and the base
is very broad. C. giddus, Ang., does not need a very close comparison, while the several
species arranged under Spherexochus by Angelin must wait for more perfect materials .
to decide their collocation.

Localities.—Carapoc Siares and Limestones of Wales, Westmoreland, and Ireland.
In North Wales,—west of Bala Lake, Rhiwlas, &c.; Corwen; Cerrig-y-Druidion, Wc. ;
Llanfyllin and other places in Montgomeryshire. In South Wales,—Sholes Hook, Haver-
fordwest; abundant. Coniston, Westmoreland (M‘Coy) ; Wexford and Chair of Kildare
(Mus. P. Geology, Woodw. Mus., &c.).

Cu. (AcrINOPELTIS) ocToLoBatus, M‘Coy. PI. V, figs. 18, 14.

? CALYMENE CLAvIFRONS, Dalm. Vetensk. Akad. Handl., p. 75, 1826.
7 — Lovén, Ib., p. 63, 1845.
SPH@®REXOCHUS CLAvIFRONS, Salter. Memoirs Geol. Survey, vol. ii, pt. 1, pl..7; figs
3, 1849.
CrRrauRvs ocToLoBatus, M‘Coy. Synopsis Foss. Woodw. Mus., pl. 1G, fig. 10, 1851.
CHEIRURUS — Salter. Decades Geol. Surv. 7, art. 2, p. 11, 1853.
CYRTOMETOPUS AFFINIS, Angelin. Paleont. Suecica, t. xxxix, fig. 10 (1855, not 1854),
(and quoting C. clavifrons of Dalman from the
originals in the Swedish Museum !)

Ch. (Actinopeltis) minor, ovatus; capite gibbo; glabelld oblonga nec ovatd; ygenis
declivibus ; caudd 8-lobatd, brevi. Glabella convexissima tuberculata granulosa, anticé
paullulum dilatata, posticé sulcis completis lobos rotundos circumdantibus ; sulcis anti-
cis longis. Gene declives, externe parvule, feré perpendiculares, scrobiculate ; oculis
minutts. Pleure spinosa. Cauda transversa bis quam longa latior, subplana, axe haud

70 SILURIAN TRILOBITES.

eminente ; pleuris utrinque 4 equalibus ovatis planis, apicibus omnibus ovatis retrorsis, nec
radiatis.

A pretty species, which I was glad to recognize as an old friend, when Mr. Henry
Woodward called my attention to it in the British Museum. C2. octolobatus had long
been described from the tail only ; but it was not suspected that it belonged to the section
Actinopeltis, and was so nearly allied to the Ch. clavifrons as to make its separation a
matter of critical distinction. If it be the Cyrt. afinis of Angelin (he has only figured the
head in a side-view, and described it as smooth), our British name must give way to the
prior one, for it seems to be really the long-contested C. clavifrons of Dalman.

It is a small species, the three caudal shields known not indicating a fossil much
larger than one and a half inch long, of which the gibbous head occupies rather more
than a third, and is a little broader than the body, with steep, almost vertical cheeks,
which, measured in their own full width, are equally wide with the glabella, but do not
appear so in a front-view. The glabella is oval-oblong, blunt in front, and rather broadest
there, where it overhangs a narrow, very distinct margin. A line taken from front to
back is regularly convex, and the glabella is much elevated, both above the front margin
and the narrow neck-segment. ‘The glabella-furrows are a basal pair, which completely
surround the rotund-oval basal lobes, only somewhat fainter where they join the neck-
furrow; and two upper pairs, rather long, placed at equal distances, the middle furrow
being about the length of the basal lobe apart from it, and as remote from the front one.
The front furrow comes thus very forward, and on a line with the deep marginal furrow
of the cheek, opposite the notch between the facial suture and this margin. The cheek
is rudely triangular, strongly margined all round (spinose, probably, at the head-angles),
and with the very small eye placed on the side of the declivity, and a good way in advance
of the middle of the cheek, opposite the ocular furrow. The free cheek is small and trian-
gular, bisected by the deep marginal furrow. The cheeks are scrobiculate all over, the
glabella covered with fine granules, and scattered larger tubercles, very equally.

Body-segments eleven, with a broad axis, equal to the pleura, and only abruptly
tapering in the two or three last segments. The pleure semicylindrical, the posterior
portion being so broad and convex as to occupy nearly the whole width of cach,’ the
fulcrum placed rather far out, and the pleuize then bent downward and a little backward,
facetted distinctly, and ending in a point. ‘The hinder ones are most bent back, and
follow the curve of the tail-border.

Tail transverse-oblong, nearly rectangular, the segments ending regularly behind, along
a nearly straight line. ‘There are four on each side, the front ones bent at right angles,
and all nearly equal, with bluntish ovate tips. No space between the two terminal ones.
The axis short, of two segments and a very small terminal portion.

1 There is no central line in this, to indicate a pleural groove, as in Eccoptochile (and some species of
Actinopeltis). It would appear that this character is not even of subgeneric value in some cases.

CHEIRURWS. 71

Comparing the side-view fig. 13, a, with the side-view fig. 11 of the nearly allied
species, C. juvenis, we at once see that it is distinct, and at the same time how very closely
these species of Actinopeltis approach each other. ‘The glabella of C. juvenzs is oval, not
oblong, and the free cheek less triangular, and a good deal larger, judging from the much
smaller fixed cheek left behind. The eyes, too, are placed far more backward, and the
neck-segment is more prominent, And if I am right, as I believe, in referring the tail
(fig. 12) to that species, there is, of course, no need to compare them minutely,

Cyrt. afinis of Avigelin is very like ours; I think it can only be a synonym.

Localities—Greenish Carapoc Sandstone of Pinwhapple, Ayrshire (Brit. Mus.) ;
Rhiwlas, Bala, and Cerrig-y-Druidion, Denbighshire (Mus. P. Geology).

Ca. (CunrRuRUS) GEeLAsinosus, Portlock. Pl. V, figs. 6—8.

AMPHION GELASINosUs, Portlock. Geol. Rep., t. ili, fig. 4, 1843.
ARGES PLANOSPINOSUS, Id. Ibid., t. v, fig. 9.
CHEIRURUS GELASINOSUs, Beyrich. Bohm. Tril., i, p. 19, 1845.
— PLANISPINOSUS, Bronn. Ind. Pal., 1848.
-- GELAsSINOSUS, Salter, Quart. Geol. Journal, vol. vii, pl. viii, fig. 1, 1831.
Decade 7 Geol. Survey, art. 2, p. 11, 1853. Siluria, 2nd
ed., p. 538, 1859.

Ch. (Cheirurus) depressus, 3-uncialis. Caput transversum, glabelld rectangulari, suleis
brevibus transversis, lobo frontali brevi, basalibus oblongis transversis viv circumscriptis,
uno ab altero spatio equali sejunctis; genis lutis, marginibus aepressis, spinis brevibus.
Cauda (hic haud dubie referta) lata, segmentis utrinque tribus latis, ad basin longe adnatis,
acuminatis ; primo in appendicem longam producto, secundum longé excedente, hoc tertium
brevem superante ; ave 4-annutato, articulo ultimo minimo angusto, nec apicem caude
profundé emarginatum attingente.

The specimens figured by General Portlock’ no doubt belong to one and the same
species ; and the form has been recognized by both Beyrich, Barrande, and myself, as a
Cheirurus. Jt is rather a remarkable one, for the extreme width and shortness of the
head ; but the tail is of the ordinary form for the genus.

We have specimens of the head nearly two inches wide ; the whole length may have
been three and a half inches, of which the short, wide head measures only ten lines. The
glabella is not so wide as the cheeks, and is rectangular-oblong, with the upper angles
slightly rounded, and the sides strictly parallel. The furrows equal in length, rather
long, oblique, and but little curved downward, the basal ones complete, and enclosing
triangular oblong lobes, separated from each other by a space equal to their own diameter.

1 While these pages are printing, we have to record the loss, at an advanced age, of this distinguished
man. His work in various departments will endure long, for it was done well.

72 SILURIAN TRILOBITES.

‘The neck-furrow strong. The forehead-lobe is small, generally equal in breadth to the
rest, but no wider; the other lobes equal in length and width. ‘The axal furrows are deep
and strong ; in them, opposite the front furrows, are deep pits on each side in the cast,
which indicate the place for the processes, which join the corresponding projections of the
labrum. ‘The cheeks are convex, wide-triangular, with a broad margin, and a narrow,
deep neck-furrow, continuous, as in all the genus, with the outer marginal furrows. The
free cheek is small; the eye small, and placed midway on the most convex part of the
cheek; the facial suture curving strongly inwards above the eye, and outwards and
upwards behind it. Spines short? and rather thick, directed backward. The whole
cheek is closely pitted, and the glabella and neck-segment sparsely covered with coarse
tubercles. ;

The tail (Arges planispinosus, Portl.) is very flat, and moderately transverse, with a
broad triangular axis of three rings, and a minute terminal appendix, which does not quite
reach the notched apex. The upper side-lobes or pleuree are largest and longest, broad-
lanceolate, with a short pleural groove, and directed outwards; the second pair ovato-
lanceolate, and diverging but little; the terminal pair of the same shape, but parallel, and
with a deep notch between them. All the lobes are adnate, but strongly separated by
furrows, and extend backward to about the same distance. Surface unknown.

Localities —Caravoc. 'T'yrone (figs. 7, 8); Ayrshire (fig. 6), in the Craig Head Lime-
stone (Mr. J. C. Moore), occurring with Heliolites, Petraia, and Pleurorhynchus. (All
three figured specimens are in the Mus. Pract. Geology.)

Cu. (Cuxrrurus) cancrurus, Salter. Pl. V, fig. 15 (and 16°).

CHEIRURUS GELASINOSUS, M‘Coy. Synops. Sil. Foss. Ireland, p. 44 (not of Portlock).
1846.
— caNncruRvs, Salter. Decade Geol. Surv., No. 7, Art. 2, p. 11, 1853.
_ — Id. —_‘Siluria, 2nd ed., p. 538, 1859.

Ch. ( Cheirurus) satis magnus, cauda lineas 20 lata, transversd, apice abrupte truncato
pramorso ; axe lato, annulis quatuor subequalibus, tertio a quarto punctis binis remotis
solum separato ; lateribus spinis quatuor longis sub-parallelis, ad basin adnatis, transversis,
apicibus lente decurvatis ; basalibus utriusque lateris longo intervallo remotis.

A most remarkable species, in which the four lateral lobes of the tail start horizontally
from the broad axis, instead of gradually converging beneath it, and leave its apex bare ;
the breadth of this space being increased by the outward direction of the spines themselves,
which begin to curve downwards only when they have attained half their length. The
appearance of the perfect tail is just like that of a crab; premorsus might have been an
appropriate specific name. C. obtusatus, a Bohemian species, somewhat resembles this ;
but the spines are radiating, not parallel. None of Angelin’s Lower Silurian Swedish

CHEIRURUS. 73

species are very like this; C. clavi/rons, Dalm., and C. Sarsii, Angelin, have some relation
to it; but the C. conformis, from the Wenlock of Gottland, is apparently a near ally, and
but for the swelled terminal lobe and wider cheeks, might have been identified with ours
(see his pl. xxi, fig. 3.)

The species is named from the tail only. It is an inch and three quarters broad, and
quite transverse, consisting of both axis and pleure of four segments, which are less con-
nected together than usual, even in this genus; and the pleure are less metamorphosed
than in any that I know. ‘The axis is very broad, and regularly conical ; broadly truncate,
reaching to the end of the tail. There are four side-lobes or pleura, the first two of
which are equal in length, and the others but little shorter. All are directed straight
outwards for a third of the length, and then curve gently backward, leaving the whole
truncate blunt tip of the axis exposed.

C. cancrurus? Tead, fig. 16.

The head, which is here provisionally associated with the species, may belong to quite
a different one ; for it is much elongated, the length equal to two thirds the breadth. The
glabella, including the very prominent neck-segment, is not far short of being twice as long
as broad. ‘I'he basal lobes complete and spherical-triangular, the upper furrows short and
somewhat curved. The forehead-lobe is as long as all the rest, exclusive of the neck-lobe.
The surface finely granular. ‘The eye placed far back. ‘he fixed cheeks narrow and
scrobiculate. ‘The margin strongly marked, but narrow. Spines ?

Locahty. Carapoc Limestone of Chair of Kildare, Ireland (Mus. Pract. Geol. The
head in the cabinet of Sir R. Griffith, Dublin).

Section.—Eccortocnite. See p. 61.
Cu. (Eccoptocniir) Sepewicxi. PI. V, fig. 17.

Crypuaus Sepewicxi, M‘Coy. Ann. Nat. Hist., 2d ser., vol. iv, p. 406, 1849.

EccorTocHILE — Id. Synops. Pal. Foss. Woodw. Mus., p. 155, pl. i, F,
fig. 14, 1851.
CHEIRURUS? — Salter. Morris’s Catal., 2nd ed., p. 107, 1854.

_ — Id. Siluria, 2nd ed., p. 538, 1859.

Ch. (Eecoptoch.) triuncialis, rectangularis, subplanus, axe angusto, caudé latissimd.
Caput (imperfectum) semicirculare ?, glabellé genis angustiore, subclavata, sulcis decurvis,
basalibus feré completis ; oculis anticis, genis latis profunde scriptis. Thorax segmentis 12,

10

74 SILURIAN TRILOBITES.

axe convexo, angusto, latitudine pleure dimidium haud effciente ; pleuris latis planis
punctato-sulcatis, apicibus acutis lenté decurvis, secundo et tertio sese conniventibus. Cauda
lata, axe brevi turbinato 4-annulato, annulo terminal trigono apicem emarginatum attin-
gente ; pleuris 6, primum rectis (duobus primis semisulcatis) dein arcuatis, apicibus retrorsis
foliaceis ovatis subequalibus. ,

I cannot do better than extract Prof. M‘Coy’s excellent description from the work
above quoted, and I think he is fully justified in placing this Lower Silurian form in the
subgenus Eccoptochile. It is, indeed, a near ally of Cheirurus claviger, Beyrich, from
which, however, its rectangular, not ovate, shape, and broad transverse flattened tail easily
distinguish it.

“Cephalic shield nearly semicircular; glabella slightly clavate, smooth, with three seg-
mental furrows on each side; the posterior pair longest, turning backwards and inwards nearly
to the neck-furrow, enclosing a triangular space on each side longer than wide, the width
rather less than that of the undivided portion of the glabella beneath their bases, the two
anterior pair of furrows shorter ; cheeks broad, gently convex, closely and coarsely pitted ;
neck-segment thick, smooth ; eye-line extending with a slight curve to the margin in front
of the angles; axal lobe very convex, narrow, slightly tapering, nearly parallel-sided,
smooth, of twelve segments; three similar rings belong to the pygidium, a fourth terminal
one being obtusely trigonal; the side-lobes are flattened, and more than double the width
of the axal lobe; pleurz nearly straight, narrow, and, for the greater part of their length,
flattened, and having a broad, nearly mesial, pleural sulcus, deeply punctured like the
cheeks, dividing each into two parts; the posterior largest, and forming a thick, smooth
rounded ridge in the distal third of its length, bent down and a little backwards, swelling
to a thick, narrow ridge in the middle, the sides and the extremity expanding into a broad,
thin, foliaceous appendage; the pygidium terminates in six broad, ovate, leaf-like, semi-
membranous flaps. Length of thorax and pygidium two inches two lines, width two
inches three lines ; width of axal lobe six lines.

“This magnificent Trilobite can only be confounded with the Xecoptochile clavigera,
Beyrich, from which it is distinguished by the much greater width of the lateral lobes of
the thorax, and the thin, flat, leaf-like appendages of the pygidium, which in that species
resemble thick, pear-shaped clubs.”

Locality, Luanprito ¥uaes, two miles north of Builth, Radnorshire (Woodwardian
Mus.), Also Abereiddy Bay, Cardiganshire (Mr. H. Hicks).

Ca. (Eccorrocnize) Freperict, 2. sp. Pi. V, figs. 18—21.

Currrurus Frepertici, Salter, in Mem. Geol. Surv., vol. 5, (ined.), pl. viii, fig. 1—3.

Ch. (Eecoptochile) triuncialis et ultra, capite transverso, longispinoso. Glabella
oblonga parallela seu anticé angustior, granulosa, sulcis distinctis abbreviatis obliquis quasi

CHEIRURUS. 75

radiatis, lobo antico parvo trigono. Gene scrobiculate nec scripte, longispinose. Oculi
omnino antici, parvi. Thorax axe modico, feré ut pleuras lato, his conveais rectis, profunde
suleatis, apicibus recurvis 4, longispinosis. Cauda major, axe 4-(vel.- 7 ?)annulato, longo,
limbo sulcato et in spinas 6 retrorstim flecas subparallelas productis.

This Trilobite, found about five years since by Messrs. Homfray and Ash, in the slates
of Portmadoc, is a member of a group more characteristic of higher beds. There cannot
be much doubt of the genus, and though the long spinous hinder pleure are a new
character for this section of Chezrurus, it can only be compared with such species as the
Ch. (Eecopt.) claviger, before mentioned, and the &. Sedgwicki, From both, the spines—
and the deeply grooved, not punctate, plearee—distinguish it easily ; I am not quite sure if
fig. 21 belongs to this or to a distinct species; it is much larger, and has more joints
in the tail.

Occasionally as much as three and a half inches long, and rather wide (all our speci-
mens are much compressed). ‘The head is wide, less than semicircular ; the outer cheeks,
occupying the greater part of the head, are margined all round by a continuous furrow,
and produced into long head-spines; the border smooth. The eye is very far forward,
as in #. Sedgwicki, and the facial suture so forward as to cut the outer margin much in
advance of the middle of the head, separating a very small free cheek.

The glabella is not nearly so wide as the cheeks; it is parallel-sided, apparently not
much longer than broad, and has the furrows very distinctly marked. These are three on
each side, and rather deep, all straight and inclined a little upwards, the front ones
especially, so as to have a radiate appearance. ‘They reach more than one third across the
glabella, and thus leave but a narrow space down the centre. The front lobe, marked
out by the two converging front furrows, is a wide triangle, and does not occupy more
than a third of the length of the glabella, the surface of which is granulated.

Thorax apparently of only eleven flattened rings, of which the axis is not quite so
wide as the pleurze; these last are convex and deeply grooved along the middle, almost
to the ends; each is produced into a long, sharp spine, bent backward in all the
segments ; but in the four or five hinder ones the spines are fully equal to the length of
the pleurz themselves,

The tail, which can hardly be distinguished from the thorax, has in the more perfect
specimen (fig. 18), only four joints and a terminal piece to the axis. In fig. 21 there are
six or seven rings. ‘Ihe smaller specimen has the tail-spines more lateral. In the larger
one they reach more toward the end of the tail; but part of this difference may be due
to pressure.

C. Eryx, a species described by Mr. Billings from the Quebec limestones,* has a
larger number of tail-spines ; but it is a closely allied form.

Locality. Urrnr ‘TREMADOC SLATES ; Garth Hill, and Penclogwyn, Portmadoe (D.

* In the ‘Canadian Naturalist and Geologist,’ vol. v, p. 322.

76 SILURIAN TRILOBITES.

Homfray, Esq.). Mr. Frederic Ash, formerly of Portmadoc, contributed many specimens
of Tremadoc fossils to the Museum of Pract. Geology; and the species is named after
him, to record his Jabours in the district.

SpHzREXocHuS, Beyrich.

Eyes facetted minutely ; head very convex, almost globular ; the cheeks not scrobiculate ;
facial suture ending on the external margin, near the angles, in front continuous and sub-
marginal; glabella large and nearly spherical, with three furrows on each side, the two
upper very obscure, the lower strong and curved down to the neck-furrow; thorax of
eleven joints, without any furrows; tail of three segments, free at their ends; labrum
subtrigonal, with a marginal furrow, but without lateral fnrrows. No rostral shield.

As the labrum of the last described section of Cheirurus, viz., Actinopeltis, has a very
similar labrum, it might be difficult to say in what, except in proportion, and in the
extreme convexity of all the parts, this very abnormal Trilobite differs from that subgenus.
However, as Sphzerexochus is widely recognised, and as, moreover, there appears to be no
rostral shield (that of Cheirurus is well established by Barrande), it is convenient to adopt
the name.

SPHAREXOCHUS MIRUS, Beyrich. Pl. VII, figs. ] —6.

CaLYMENE CLAVIFRONS, Hisinger. Leth. Suec., 2nd Supp., t. xxxvii, fig. 1, 1840.
SPHHREXOCHUS MIRUS, Beyrich. Ueber einige Bohm. Tril., p. 21, 1845.

_ — Id. — Zweite Stiick, t. i, fig. 8, 1846.

_ caLvus, M‘Coy. Syn. Sil. Foss. Ireland, pl. 4, fig. 10, 1846.

_— Mirus, Corda. Prodom. einer Monog. Bohm. Tril., fig. 72, 1847.

— — Barrande. Syst. Sil. de Bohéme, vol. i, pl. xlii, figs. 11, 18,

1853,
—_ — Salter. Decades Geol. Surv. No. 7, pl. iii, 1853.
— ~ Id. — Morris’s Catal. 2nd ed., p. 115, 1854.

A few years ago this was one of our rare British Trilobites. Now, the accident of a
tunnel being driven through the rich formations of the Malvern Hills has rendered it one
of the most frequent ornaments of the cabinet. Messrs. Gray and Fletcher obtained the
species first from the Dudley Limestone. Sir R. Griffith found it in the Caradoc Lime-
stone of Kildare, and Prof. M‘Coy published it almost immediately after Beyrich’s
description had appeared in 1846. The Geological Survey collected it in abundance from
the same locality in Ireland; and now our friends, Dr. Griudrod, of Malvern; Messrs.
Hollier and Ketley, of Dudley; and Messrs. Allport, of Birmingham, have contributed
excellent materials, which enable us to complete the account.

SPHAREXOCHUS. 77

Larger specimens have lately occurred ; and the finest I know, in Dr. Grindrod’s collec-
tion, is nearly two inches long. Of this the head occupies more than a third of the whole
length, and the glabella is very large, occupying, as seen from above, four fifths of the
width, and quite overhanging the narrow front margin. It is, excluding the neck-segment,
nearly a true hemisphere, and has a pair of large orbicular lobes at the base, deeply cir-
cumscribed, and further apart from each other than their own diameter. The furrow that
bounds each of these lobes is broad, sharp, and equal in depth all round, leaving no com-
munication with the body of the glabella (figs. 4, 5, 6). Above these lobes, on each side,
are two faint impressed lines, which represent the upper furrows (see fig. 5, a); of these
the one next to the round basal lobe is placed at a less distance from it than the
diameter of that lobe, at about the point of the head’s greatest width, and the upper one
at an equal distance in advance of it towards the front. The cheeks are small in com-
parison with the glabella, and hang vertically from its sides (fig. 5, cc), like a pair of
lappets from a cap or helmet; they are oblong, and have a thickened margin. The small
convex eye is placed very near the glabella, and below the middle of the head; the facial
suture runs outwards from it, and reaches the exterior margin, which it cuts obliquely, a
little in front of the posterior angle, as is fig. 6; in front of the eye it continues parallel
to the glabella, and runs along the edge of the narrow front margin, leaving the free
cheeks connected beneath by a narrow band (fig. 5, 4). The free cheek is hatchet-shaped ;
and the small eye (fig. 5, c) occupies the inner corner, supported on a fold of the crust,
which truncates, or even indents it below. ‘The eye is thus pushed up into a supine
position ; it is short, oblong, and very convex. ‘The lenses are numerous, larger in size
than the granulations of the general surface, and placed near together, less than half their
diameter apart. In this specimen we have not the outer surface sufficiently perfect to
enable us to say whether the cornea is raised into facets (as Barrande thinks) or not ; from
the inferior surface (fig. 5, d) the lenses have fallen out, leaving pits which indicate their
size. The posterior corners of the head are rounded off, and they bear, instead of a
spine, only a small tubercle (fig. 6), which is placed far inwards.

The labrum has not yet been found in England, but it is figured in M. de Barrande’s
plates, and we reproduce it from a Bohemian specimen (fig. 5, e). It is trapezoidal or inverted-
pyramidal, half an inch wide by four lines long, straight at the base, where it is much
broader than it is long, and the apex is truncate and slightly emarginate. A broad,
shallow furrow runs round the end and sides, leaving only a small central convexity of the
same shape as the labrum. ‘This convexity is not indented by any lateral furrows. The
auricles (see p. 60) are brought to a level with the base, and thus no notch is left between
them and the ascending processes, as in those of forms of Chedrurus which most resemble
it (see Barrande’s plates, xl, fig. 30, and xlu, fig. 19).

The surface of the head is covered by a fine, close granulation (fig. 6), which occupies
also the free cheeks or wings; it is, therefore, one of the subgeneric distinctions from
Cheirurus, in which the cheeks are always pitted or scrobiculate.

78 SILURIAN TRILOBITES.

‘Thorax parallel-sided, scarcely tapering backwards, of eleven thick rounded rings ;
the axis as wide as the sides, and of equal breadth throughout, very convex ; each joint
much raised and rounded (see fig. 4). Pleurze horizontal as far as the fulcrum (fig. 6, d),
and then abruptly deflexed, and from this point the pleura tapers outwards to a conical
blunt point, which, at the extreme tip, is a little bent forwards. The fulcrum is placed at
rather less than half way from the axis ; but in the last segment it approaches much nearer,
—to about one third (fig. 6,7). Its place is indicated by a protuberance, both on the forward
and hinder edge of each segment (fig. 6, d and f); but these swellings are not isolated
tubercles, as in Chezrurus, nor are there any oblique or longitndinal furrows on the pleure,
as in that genus, to break up the uniform convex surface of the segment.

Tail about semicircular, truncate ; the axis conical, its base of two depressed close-set
rings, its apex of one long triangular joint, which is separated from the second joint by a
deep depression; from thence it is flattened, or even depressed, for some distance, but
suddenly rises to an obtuse and elevated tip (fig. 6, g). When seen endwise the tail
presents a bent appearance. ‘The sides are composed of three obtuse convex lobes, which
scarcely project on the-margin; the upper one follows the bend of the hindermost
pleura, the second is less curved, the third parallel to the axis; all are deflected, so that
an end-view of the tail gives an angular outline, very distinctly seen in the Decade figure
above quoted.

The entire surface of the thorax (fig. 10) and tail, like that of the head, is covered
with a fine granulation, the grains of equal size throughout.

Variations.—Our Dudley specimens have the tail somewhat shorter and wider, and
the terminal joint of the axis therefore shorter, than those from Bohemia. Irish speci-
mens (figs. 14, 15) are more like the foreign ones in this respect. The space between the
lower glabella-lobes is least in these Irish specimens, though some of them have it con-
siderably wider than the diameter of the lobes; in a Wexford specimen the space is pro-
portionally as wide as in those from Dudley, which often have the lobes as far apart as in
Bohemian examples.

The species we have to compare this with are many. These are :—the 8. scabridus of
Angelin, which differs but little, and may be identical ; the S. angustifrons, id., which has
flat, expanded lobes to the tail; §. deflecus, S. granulatus, S. conformis, and S. Wegelini,
of the same author, have incomplete basal lobes; one figured, but not named, by
Dr. Beyrich in his second paper (1846), which has the lobes of the tail lengthened out,
and the terminal joint of the axis short.* An eighth is that figured in the lower part of
our plate (figs. 27, 28), possibly a Cheirwrus of the Actinopeltis group ; but having such
marked basal lobes, I regard it as a Spherexochus for the present. The Jast I shall notice
is from the Lower Silurian Rocks of Thibet, and has been figured from Col. Strachey’s

This ought to receive a name, The genus is too scanty to render it inconvenient. S. Beyrichii
would do very well for it.

SPH REXOCHUS. 79

work.* The projecting bullate lobes of the glabella, in the Indian fossil, give the aspect
of staring eyes, and suggested the term S. zdiotes. Most of the above-mentioned are
apparently, but rare species. The really cosmopolitan fossil is the S. mirus, which has
been found in Bohemia, Sweden, Britain, and North America.

Localities. —Carapoc Rocks; Chair of Kildare, Co. Kildare ; Carrickadaggan,
Co. Wexford; Biggar, Lanarkshire (specimens all in Mus. P. Geology). Woonnopn
Limestone ; Malvern? Wenitockx Limesronz and Suatz; Dudley, Walsall, Malvern,
abundant.

Abroad it is found in Lower Silurian strata of Dalecarlia (Hisinger), Upper Silurian
of Bohemia (Barrande), and in Ohio, North America. From the latter locality I have seen
specimens in Sir C. Lyell’s collection, and M. de Verneuil also quotes it from thence.

SpH#REXxOcHUS? Boops, 2. sp. PI. VI, figs. 27, 28.

CHEIRURUS CLAVIFRONS, M‘Coy. Synopsis Pal. Foss, Woodw. Mus., pl. i, F, fig. 12,
1851 (not the other figures, nor of Dalman, nor Angelin,

nor Sars and Boeck).

I must give this a name, both because of the paucity of British forms of this genus, and
to call further attention to it. I had long named it as a distinct species in the Jermyn
Street Museum ; and lately I have found, by the correspondence (and a careful drawing)
of the talented Mr. Harry Seeley, of Cambridge, that M‘Coy’s figure quoted above repre-
~ sents a more complete specimen than the one in Jermyn Street (fig. 27). M‘Coy’s specimen
is correctly represented in fig. 28. There is some doubt of the genus, for it may belong to
the section Actinopeltis of the group Chezrurus, but the general character is much that of
Spherexochus, and we do not yet know the limits of these two subgenera, for such they
assuredly are.

I shall content myself with an English description, and only point out its charac-
teristics. It is a larger form than 8. mirvs. ‘The glabella is of an oblong-ovoid shape,
very convex, almost gibbous, but not so greatly so as is that of the Cyrtometopus gibbus,
Angelin, a very near ally.

The basal lobes occupy nearly one half of the length of the glabella; they are wider
than long, and somewhat oblique,—their shape compressed-spheeroidal, not truly round, and
on the inner side they are connected with the body of the glabella by a depressed neck,
about half as wide as the width of the lobe itself. The pair of lobes stand apart about as
far as their shorter diameter. ‘The neck-furrow is strong, and much arched forwards,

* The work is yet unpublished. But the plates and descriptions have long been printed. The
Trilobites (nine species) are figured in Plate I. Among them is a new type allied to Cheirurus, but with-

out eye or facial suture (Prosopiscus, Salter).

80 SILURIAN TRILOBITES.

and is very prominent and elevated, but not broad ; neither of our specimens show its full
width.
The strong convexity of the spe eye-like lobes suggests some such name as the

above.
Locality—Canranoc Suatzs of Sholes Hook, Haverfordwest (fig. 27, Mus. P. Geology),

Applethwaite Common, Westmoreland (fig. 28, Woodwardian Mus.).

Ampuion, Pander, 1830.*

Head short, transverse, without spinose angles. Glabella nearly rectangular, with
three pairs of furrows, the front pair generally approximate on the anterior margin, and
always enclosing a very small forehead-lobe, often narrower than the glabella. Eyes
small [reticulate, Angelin]; facial suture behind the eyes ending on the exterior margin a
little im advance of the rounded angles; labrum entire, pointed, convex, margined all
round; body with fifteen to eighteen rings, the pleuree without grooves; tail of few
segments, the axis short, the pleurz with free terminations [includes P/iomera of Angelin,
1852].

Amphion is just one of those genera which show the near connection between the
Cheiruride and Calymene, to which it is allied by the elongate form, numerous body-
segments, glabella not widened in front, and facial suture ending nearly in the angles.
On the other hand, it is like Zethus and Cybele by the grooveless pleure and free
segments of the tail, which extend beyond the margin as in those age and close behind
the shortened tail-axis ; also by the entire labrum.

From both groups the peculiar shape of the glabella and the numerous unfurrowed
pleurze distinguish it. The typical species is the Asaphus Fischeri of Eichwald, which was
called Calymene polytoma by Dalman. Pander established the genus Amphion, but again
altered the specific name. In 4. Mischeri there are eighteen body-rings.

AMPHION PSEUDO-ARTICULATUS, Portlock. Pl. VI, figs. 29, 30.

AMPHION PSEUDO-ARTICULATUS, Portlock. Geol. Rep. Londond. Tyrone, pl. iii, fig. 5,

1840.
_— _ Salter, in Morris’s Catal., 2nd edit. p. 99, 1854.
_ —_ Id. Siluria, 2nd ed., p. 537, 1859.

A. triuncialis, longus, axe | glabellaque convexis, fronte haud contracto. Caput semi-
crculare, margine angusto. Glabella subparallela, convexa, lobis brevibus, subradiatis,
antico quam glabella lato, transverso, lineari. Oculi retrorsi, prope glabellam positi.
Thorax segmentis 17, axe convero. Cauda expansa, pleuris subclavatis 5, duobus termi-
nalibus post avin abbreviatum subplanum omnino connatis.

* *Beitrage zur Geognos. des Russich. Reiches,’ Petersburg, 4to.

AMPHION. 81

It was a proof of the late General Portlock’s scientific acumen to have decided this to
be an Amphion, a genus, be it remembered, never recognised in Britain before his work
appeared ; for assuredly the characters of the head are unlike those of the typical species,
and yet there is no manner of doubt we must admit it, and enlarge the generic character
so to do. The forehead-lobe is much wider in this than in the other species, as our
woodcut will show. (Fig. 17.)

The species probably grew three inches long, as indicated
by fig. 30. The head is transverse, semicircular, or nearly
so; the glabella, which is moderately convex, occupying fully
one third, and regularly, but very slightly, tapering back-
wards to the small neck-segment. The furrows are three
on each side, very short, and somewhat radiating, en-
closing a linear basal lobe, a clavate middle one opposite the eye, and a subrectangular
upper lobe, between which and the very short, wide, and transverse forehead-lobe is only
a short, straight furrow; but beneath this it is continued asa faint curved depression
(not shown in our figure), so as to follow the direction of the middle or ocular furrow.
The forehead-lobe (and this is unusual for the genus) is as wide as the rest, and is a
narrow linear segment. It has no central furrow, such as exists in 4. Mischerz, nor any
crenulate border in front ; indeed, the front margin must have been very narrow, as our
figure (woodcut 17) indicates.

The cheeks’are triangular and gently convex, strongly and rather deeply marginal, the
margin being not so broad externally as in 4. Fischeri, and the cheek consequently more
triangular and less oblong. The eye is placed far inwards for the genus, and only
one third up the cheek. We have not the actual eye. It was small, but is not preserved
in our specimen. ‘The facial suture curves largely out and upward beyond the eye, and
cuts the obtuse head-angles.

As the glabella is more convex than usual in the genus, so is the axis of the thorax
which follows it, and which is not so wide as the sides, but wider in proportion than other
species. ‘The pleuree are each convex, especially within (in the cast), and have the fulcral
point at one third, whence they bend backward and curve downward. No pleural groove
shows on the exterior surface, but within the crust the furrow is visible on the anterior
edge of the segment.! The extremities are curved, and apparently rounded, but this
last may be deceptive.

The tail is remarkable, and in our largest specimen (fig. 30) shows well the characters
which separate it from 4. Mischerz. Its parabolic flattened axis, divided into five rings,
reaches barely more than half the length, divided by only fait axal furrows from the five
side pleurze, of which four are well distinct on each side, and have a sublinear but some-

1 This is usual in all genera with ungrooved pleurze, and hence the distinction of those groups which
have ‘‘plevre a sillon,”’ from those which have ‘plevre 4 bourrelet”’ is an artificial one. Cheirurus and
Spheerexochus show the intermediate character.

il

82 SILURIAN TRILOBITES.

what clavate form, the truncate ends being oblique. The two terminal ones close so
completely behind the axis that the suture is soldered, and they appear as a single rectan-
gular plate, with a terminal notch only. The whole tail is gently and regularly convex,
and the appearance thus given is very peculiar.

Locality—Caravoc Suiate of Tramore, County Waterford (Mus. P. Geol.).

AMPHION BENEVOLENS, n. sp. PI. VI, fig. 31.

A. minor, capite (solum cognoto) lenté convexo, latimarginato, margine frontali incras-
sato nec crenulato. Glabella lenté convera anticé latior, lobis longis transversis, antico
abbreviato triangulari, vie plus quam dimidium frontis efficiente ; sulco centrali nullo. Oculi
retrorsi, & glabelld paullum remoti. Reliqua absunt.

Much more nearly like the Russian species than the one above described. A. dene-
volens, named in honour of Mr. Nevins, of Waterford, differs from that species in its pro-
portions, and in the presence of a plain, thickened, anterior margin instead of the crenulate
border visible in the Scandinavian fossil. It is about the same size. We have only the
glabella and a part of the cheeks, which show the eye to have been also very much nearer
the glabella than in the species just quoted.

Head seven lines long and about fourteen wide, semicircular, a little pointed in front,
gently and regularly convex, the glabella being just as long as broad above, and tapering
slowly behind—the axal furrows quite straight. A thick margin runs round the front,
quite free from corrugations, and with a small tubercle in the centre, the division between
this margin and the glabella being feeble for the extent of the forehead-lobe, which occupies
rather more than half the whole width of the glabella in front, and has a pair of very
oblique, faint, straight furrows to bound it. Outside this the marginal furrow is as deep (in
the cast, which is all we possess) as the abrupt axal furrows of the head. The middle and
basal furrows are long, reaching more than one third across the glabella; the middle one
straight at first, then gently decurved, the lower one quite straight, and all of them deepest
at their inner termination. The neck-furrow rises considerably toward the middle, so as
to make the basal lobes cuneate, but neither the neck-segment nor any of the lobes are
tumid. All partake of the regular and gentle convexity of the head.

The eye is placed opposite the median lobe ; it is small, but elevated, and surrounded
by a rather deep furrow, and it is only about twice as far from the glabella as from the
neck-furrow (in 4. Fischeri it is three or four times as remote).

Locality —Caranoc Siatz of Newtown, Waterford, in company with Phacops Jamesii,
described at p. 32.

AMPHION.. 83

A. PAUPER, n. sp. PI. VI, fig. 32.

Omnino precedenti simillimus, nist margine antico angustiore, lobis glabelle longiori-
bus radiatis, postico sinuato, mediano valdé obliquo recto, antico obsoleto. Glabella lenté
convexiuscula, lateribus paullum arcuatis. Oculi subremott.

One specimen only has been preserved of this neat species, which is truly distinct. It
is about the same size as the preceding, from which, at a glance, you may distinguish it by
the long glabella-furrows, and when closely examined it is found that there is one pair
absent, viz., the obsolete anterior ones. A faint marking only indicates their proper
position. .

Glabella, including the narrow front border, as long as broad, regularly and gently
convex, arched slightly in front; the sides not straight, but curved outwards ; the upper
angles rectangular, Anterior border narrow, not thickened. Anterior furrows quite
obsolete. Median furrows starting from the upper angle or a little below it, straight,
oblique, and reaching far towards the centre. Lower furrows situated opposite the eye,
and reaching nearly as far as the upper ones. The middle lobes are thus subcuneate, the
basal lobes broad-linear. ‘The neck-furrow is distinct, but shallow ; the neck-segment linear,
but not so wide as the basal lobes ; none of the glabella-furrows are thickened at their ter-
minations. Axal furrows not deep. Position of eye doubtful, but probably further
forward than in 4. denevolens. ‘The neck-furrow on the cheek is strong.

Compared with the preceding species, 4. pauper differs in nearly every part. Instead
of a thick front margin, it has a narrow one; the anterior furrows are obsolete, a very curious
character, and peculiar to this species. The median ones oblique and longer than the
basal furrows, which are sinuous instead of straight. Lastly, the head is less convex, and
all the furrows—neck-furrow, axal-furrow, and glabella-furrows—less strong. The outline
of the glabella is barrel-shaped, not rectilinear.

Locality.—One specimen only is known, from the Carapoc Rocks of Tramore, where
it occurs with the preceding (Mus. Irish Industry, B. 643).

The genera Stawrocephalus and Deiphon should follow these. If we obtain good mate-
rials during the coming summer, they shall be illustrated next. If not, it will be
better to proceed with the Calymenide.

The genera Cybele, Hncrinurus, and their allies, will be in like manner postponed.
And the Acidaspide and Lichade may well wait awhile till the more complete materials
belonging to the Calymenide, Cyphaspide, Olenide, and Asaphide, are exhausted. I
think, as the families are numbered, it cannot be of great consequence which is illustrated
first. But if the materials be forthcoming, it is desirable not to interrupt the natural
order of the genera ; and [I shall do so as little as possible.

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8.
9—15.
16.
17—19.
20.
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33, 34.
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36—38.
39—41.
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A3—45.

PLATE I.

DEVONIAN AND LOWER SILURIAN.

Phacops granulatus, Munster. From Upper Devonian Rocks. Fig. 1, Newton Bushell.
(Mr. Pengelly’s cabinet.) Figs. 2, 3, 4, Petherwin, Cornwall. (Mus.
Pract. Geology.) Fig. 4 a is fig. 4 enlarged.

ss levis, Mtnster. Knowl Hill, near Newton Bushell. (Figs. 5, 6, Mr. Pengelly’s
cabinet. Fig. 7, Mr. Vicary’s collection.)

es cryptophthalmus, Emmn.? Newton Bushell. (Mus. Pract. Geology.)

as latifrons, BRonN. From the Uppermost Devonian or Pilton Group, near Barnstaple.
Figs. 9, 10, somewhat distorted. (Mus. Pract. Geology.) (Fig. 11,
cabinet of Mr. Townshend. Hall.) Fig 11 a, eye, with spaces between
the lenses marked out into hexagonal arez on the inner cast. Fig. 12,
specimen with very prominent cups in the inner cast, z. e. with thickened
cornea. Fig. 13, specimen with thinner cornea and less prominent cups.
Fig. 14, Baggy Point, N. Devon. (Mus. Pract. Geol.)

5 + Variety with narrower axis and more side ribs. Newton Bushell. (Mus.
Pract. Geology.)

Phacops punctatus, STEININGER. Liskeard. (Figs. 17, 18, Mr. Pengelly’s cabinet. Fig. 19,
. Mus. Pract. Geology.)

», Brongniartii, Porttock, Montgomeryshire, Lower Silurian. (Mus. Pract. Geology.)
$9 56 From Tyrone. Portlock’s figured specimens. 25 a. Magnified.
ey gre Variety or 2 form. (P. Dalmani, Portlock, figured specimen.)

Phacops incertus, DEsLONGcHAMPS. Lower Silurian pebbles of Budleigh Salterton, S. Devon.
(Mr. Vicary’s cabinet.)’

=
e Jukesii, Sauter. N. Wales. (Mus. Pract. Geology.) Caradoc Rocks.
* alifrons, Id. From N. Wales (copied from figures in the Woodwardian Synopsis).

3 = », N. Wales (from specimens in the Mus. Pract. Geology). Caradoc.

= mimus, Id. Quartzite of Gorran Haven, Cornwall. (Mus. Pract. Geology.) Llan-
deilo Rocks ? '

* apiculatus, Sauter. Horderley, &c., Shropshire. Caradoc. (Mus. Pract. Geology.)

ES Jamesit, PortLock. Figured specimens, Waterford. Caradoc. (Mus. Pract. Geology.)

53 a $ Tail of the same, magnified.

# obtusi-caudatus, SauTER. Fine specimen in the Woodwardian Museum, from Coniston

Flags. Caradoc Rocks.

59 ES Variously distorted specimens. (43, 44, Brit. Mus. 45, Mr. Edgeil’s
cabinet.)

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6.
7—10.
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13, 14.
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16.
17—-25.
26—29.
30.
31—32.
33.
34.

PLATE II.
UPPER SILURIAN.

Phacops Stokesit, M1tnE-Epwarps. Abberley Hills, Wenlock Shale. (Mus. Pract. Geology.)

‘ P From Dudley. (Mr. Mushen’s cabinet.) 2 a. Head, enlarged (3 a is 3
magnified). 4. Tail. 5. Eye, magnified.

Phacops Stokesii. Locality uncertain. Wenlock Shale of N. or 8S. Wales. (Mus. Pract. Geology.)

3 Musheni, Sautur. Of various ages; from the Wenlock Shale, Malvern. 9 a. Tail,
enlarged. (Cabinets of J. Mushen, Esq., and C. Ketley, Esq.)

A - Larger specimens, Dudley. (Gray collection, Brit. Mus.)
Phacops constrictus, SALTER. Wenlock Shale, Malvern. 13 a. Tail, enlarged. (Dr. Grindrod’s
cabinet. )
8 55 (15 a, side view; 15 6, magnified.) 15 ¢. Eye of the same species. (Mr.

Ketley’s cabinet.)
E és The same species. Wenlock Limestone; Dudley. (Brit. Mus.)

Phacops anes Murcuison, var. a, vulgaris. All from Dudley and Walsall. Fig. 17, a
. cluster, in the Brit. Mus. Figs. 18, 25, the specimens figured in the
original ‘ Silurian System,’ and now in the cabinet of Mr. W. Mathews,
junr., of Edgbaston. Fig. 19, half-coiled specimen (Professor Tennant’s
coll.). Fig. 20, completely coiled (Decades of Geol. Survey). Fig. 21,
young ditto (Mr. Mushen’s cabinet). Figs. 22, 23, large specimens
(Brit. Mus., Gray coll.). Fig. 24, form with large eyes, Malvern, in
Wenlock Shale. (Mr. Ketley’s cabinet.)

Ss $5 Large-eyed variety, 8, macrops. Fig. 26 is copied from the Survey Decades.
Fig. 27, large specimen, Malvern, Wenlock Shale. (Mr. Ketley’s cabinet.)
Fig. 28. Dudley. (Brit. Museum.) Fig. 29, internal cast, from

Wenlock Rocks, near Cardiff. (Mus. Pract. Geology.)

x A var. y, inflatus. Malvern Limestone. (Dr. Grindrod’s cabinet.)

“ 1» Probably the same variety. Fig. 31, certainly so (glabella only), from
Ledbury. Fig. 32, internal cast, same locality. Both are figured in the
Decade 7, Geol. Survey, and are in the Mus. Pract. Geology.

- 3 Interior cast of tail. Eastnor, near Ledbury. (Mus. Pract. Geology.)
Wenlock Limestone.

si a Dissection of the species. (Decades Geol. Survey.) a. Anterior ring, bearing
the eyes. &. Underside of head (hypostome), bearing the labrum.
c. Glabella and fixed cheeks. d. Magnified eye. e. Lenses and interstitial
granules, still more magnified. / Casts of the cups which support the
lenses. g. Thorax-joints. A. Underside of the pleure of ditto. i. Tail
of ditto. All more or less enlarged. .

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PLATE III.

UPPER SILURIAN.

Fic. é
1, 2,8. Phacops Weaveri, Sauter. Figs. 2, 3, are from (May Hill? or) Ludlow
, Rocks, Horseshoe Farm, Tortworth. Fig. 1, the head, is
added from the May Hill Rock of the neighbourhood
to complete the figure of the species. (Mus. Pract.

Geology.)

4—14. » eaudatus, var. a. Various figures of ordinary variety, vz/garis, young
and old, from Dudley. Fig. 4, Mr. Mushen’s cabinet,
Rushall Canal. Fig. 5, British Museum. Fig. 6, in-
terior cast, Ledbury. (Mus. P. Geology.) Figs. 7, 8,
labrum, from Mr. Mathews’ and Mr. Ketley’s cabinets.
_ Fig. 9, side view of head, Dudley. (Mus. Pract.
‘ Geology.) Fig.10, eye (Dr. Grindrod’s cabinet), Led-
bury. Fig. 11, same, magnified. Fig. 12, interior cast,
Ledbury (Mus. Pract. Geology), shows the casts of
the interior of the gland-lke tubercles (see p. 52),
such as are seen on the exterior of figs. 16, 17.
Fig. 13, large but worn Dudley specimens (in Brit.
Mus.), figured by Konig under the name of Asaphus
myops. Fig 1A, fine interior, i Mr. Mushen’s cabinet.

15. £ as Young (Brit. Mus.), showing the central tubercles.

Loo 7. et nbs 4 Dwarf specimens, retaining the characteristic tubercles of
the young state; Ledbury. (Fig. 16, from my own
cabinet. Fig. 17, Mus. Pract. Geology.)

18. A Salt MLE var. 8, aculeatus. Wren’s Nest, Dudley (Mr. Ketley’s
cabinet). All the above are from the Wenlock Lime-
stone.

19—28. Phacops longicaudatus, Murcuison. Figs. 19—21, ordinary variety, a. Figs.
22—28, short-tailed variety, 8. All from Wenlock
Shale. Figs. 19, 20, are Burrington’ specimens.
(Mus. Pract. Geology.) Fig. 21, Brit. Mus. Fig.
22—25 are from the Wenlock Shale: of the
Malvern Railway. (Mr. Mushen.) Fig. 23, Dr. —
_ Grindrod. Fig. 26, Brit. Mus. Fig. 27 is from
the Rushall Canal. (Mr. Mushen’s cabinet.)

16, 04,
18—23.

PLATE IV.

UPPER AND LOWER SILURIAN.

Phacops caudatus, var. 3, tuberculato-caudatus. A large and fine specimen in

Phacops

?

2?

Dr. Grindrod’s cabinet, Lower Ludlow, Malvern.
caudatus, junior. Mr. Mushen’s cabinet, Dudley.
5 var. y, zexilis. Vinnal Hill, Ludlow. (Mus. P. Geology.)
Weaveri, Sauter. Fig. 6, imperfect head from Tortworth. (Mus. P..
Geology.) Fig. 7, tail, ordinary size, Tortworth. Figs.
8, 9, tails of mucronate variety, May Hill Schist, Marloes
Bay, Pembrokeshire. (All in Mus. P. Geology.)
imbricatulus, ANGELIN? May Hill Rocks, Presteign. (Mus. P.
Geology.) ,
mucronatus, BRONGNIART. From near Bala. (Mus. Pract. Geol.)
truncato-caudatus, PortLocK, his original figured specimens. Fig. 13,
natural size. Fig. 14, restored figure, reduced
size. Fig. 15, labrum. All from the Caradoc of
Desertcreat, Tyrone. (Mus. Pract. Geology.)

camphora, Sauter. Grug, near Llandeilo. (Mus. Pract. Geology.)

macroura, SJOGREN. From the Caradoc of Acton Scott, &c., Shropshire.
Figs. 18, 19, adult head and tail. (Ludlow Museum.)
Fig. 20, external cast of head, middle age. (Mus. Pract.
Geology.) Fig. 21, labrum (Ludlow Museum), showing
the perforation a, which marks the place of the ascending
process. Fig. 22, perfect tail, and fig. 28, very young
tail, pomted. (Ludlow Mus.)

conophthalmus, Borck? Fig. 24, young heads. (Mr. Lightbody’s
cabinet.) Fig. 25,. internal cast of head from
Llansantffraid Glyn Ceiriog, N. Wales. (Wood-
- wardian Museum) ; for figure of tail from same

locality, see Pl. VI, fig. 25.

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LOWER
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9—12.

13.
14.
15.

1G.
17.

1820.

21.

TABLE V.

LOWER SILURIAN.

Cheirurus bimucronatus, Murcu. Large internal cast from Caradoc Strata,

”?

”

Sholeshook, Pembrokeshire, also figured in Me-
moirs of Geof Survey, vol. ii, pt. 1, pl. vii, fig. 4.
(Mus. Pract. Geol.)
; Smaller head, external surface, Caradoc
Strata, Chair of Kildare. (Mus. Pract. Geol.)
Young. May Hill Sandstone of Norbury.
(Mr. W. Edgell’s cabinet.)
- - Young, distorted (Ceraurus Williamsi,
McCoy, figured specimen), Llandovery Rock,
Llandovery. (Woodw. Mus.)
Labrum of large specimen, Chair of Kil-
dare. (Mus. Pract. Geol.)
gelasinosus, Portuocx. Fig. 6, tolerably perfect surface of
Ayrshire specimen. (Mus. Pract. Geol.)
Vigs. 7, 8, Portlock’s figured specimens from
Tyrone. Both are Caradoc localities.
juvenis, Sauter. Fig. 9, exterior of glabella, Chair of Kildare.
Fig. 10, internal cast, Sholeshook, Pembrokeshire. Fig.
11, side view of same. Fig. 12, tail from Chair of
Kildare. Caradoc Beds. (All from Mus. Pract. Geol.)
octolobatus, McCoy. Caradoc of Penwhapple, Ayrshire. (Brit. Mus.)
= The same, tail from Rhiwlas, Bala. (Mus. Pract. Geol.)
(Probably this is the C. clavifrons, Dalman ; C. afinis,
Angelin.)
cancrurus, SALTER. Originally described specimen, from the Chair
of Kildare. (Mus. Pract. Geol.)
» £ Chair of Kildare. (Sir. R. Griffith’s coll.)
Sedgwicki, McCoy. Llandeilo Flags of Builth. (Woodwardian
Museum.) | ie
Fredericit, Sautur. Upper Tremadoc Slate of Portmadoc, N.
Wales. (Fig. 18, Mr. D. Homfray’s cabinet. Fig.
19, Mr. Ash’s cabinet. Fig. 20, Mus. Pract. Geol.)
Frederici 7, variety. Same formation and locality, Garth Hill, Port-
madoc. (Mr. D. Homfray’s cabinet.)

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15, 16.
17.
18.

19, 20.

21—24.
25.

26.

27, 28.

29, 30.

31.
32.

TABLE VI.
UPPER AND LOWER SILURIAN.
UPPER SILURIAN.
Spherevochus mirus, Bryricu. Dudley. (Mr. Shedden’s cabinet.) Young coiled specimen.
3 Of various ages. From the Wenlock Shale of Malvern Tunnel. (Dr.

Grindrod’s cabinet.)
A coiled-up specimen. (Brit. Mus., Gray coll.) 5 a. The head, dissected, front view, showing ©

”

the anterior glabella-furrows, and at 6 the anterior segment, the cheeks connected by the
hypostome, without the intervention of a rostral shield. c¢. The convex eye. d. The
lentiferous surface, magnified, the lenses removed.

The same viewed dorsally, and showing the strong basal glabella-furrows, the surface finely
granular. 4. The cheeks. A minute tubercle indicates the place of the head-spines. c. A
body-ring, third or fourth, showing the position of the fulcrum (d), and the prominence
behind, against which the fulcrum abuts. e. Incurved tip of pleura. f. Last thorax-
segment, the fulcrum near the axis. In this and the preceding figure the pleure are repre-
sented as flattened out to show their characters; they would appear much shorter on
viewing them from above. g. The tail, magnified. (Figs. ¢ to g are from Capt. T.
Fletcher’s Dudley collection, now in the Fitzwilliam Museum, Cambridge.)

Cheirurus articulatus, Minster. A large and a small head from Mr. Pengelly’s cabinet.

From Lammaton, Torquay, in Middle Devonian Limestone.
Zs bimucronatus, Murcuison, var. 6. A half-grown but very perfect oe,
(Cabinet of Mr. E. Hollier, junr.) Dudley.

A fine specimen, shortened by pressure, from Mr. Ketley’s collection. Same variety,—f.

A Malvern specimen, cleared by Mr. C. Ketley, and now in his cabinet. It shows the labrum
and the central mucro to the tail, var. a. - 11 6. Side view of ditto.

Labrum, also from Mr. Ketley’s cabinet.

Shows the interior view of the same organ. At a, a, the ascending processes, which are attached
to the sides of the glabella. 5, 6. The incurved triangular plates. There is a hollow space
under the ascending processes, answering to the lateral notch on the upper surface (fig. 12).

Pleurze of C. dimucronatus, from aspecimen in Mr. Mushen’s cabinet. The lower figure is an
internal cast of ditto, copied from the Decades of the Survey. a. The posterior fulcral tubercle.

_ 6. The anterior tubercle. c. Free tip of pleura. d. Cast of vertical ridge on interior surface.

Tails of young specimens, var. a. Dudley collections.

Entire young specimen, var.a. (Mr. Mushen.) Dudley.

C. bimucronatus, var. 3, centralis. Dudley. (Mr. E. Hollier, junr.)

(Figs. 19—24 are from the Mus, Irish Industry.)
Phacops nudus, Sauter. a, 6, c. Fragmentary heads. Fig. d is c mapuiiedl e. Eye,
magnified. /. The lenses, magnified. Fig. 20, tails, two specimens.
Upper Silurian Limestone, Dingle, Co. Kerry.

LOWER SILURIAN.
Phacops Bailyi, Sauter. Caradoc of Tramore, Co. Waterford. 24 a. Interior cast of tail.
6. Exterior cast.
»» conopthalmus, Borck.? Caradoc, N. Wales. (Cambridge Museum.)
Spherexochus mirus, Bryricu. Caradoc, Chair of Kildare. (Mus. Pract. Geology.)
Fe boops, Satter. Caradoc. Haverfordwest. Fig. 27 (Mus. P. Geol.). Fig. 28,
Westmoreland. (Cambridge Museum.)
Amphion pseudo-articulatus, Portuock. Caradoc of Tramore, Waterford. (Mus. Pract.
Geology.) ,
ps benevolens, Sauter. Caradoc of Newtown, Waterford. (Mus. Pract. Geology.)
9 pauper, Sautnr. Caradoc of Tramore. (Mus. Irish Industry.)

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TP AAD ARTY SP UCIVZEI

PALMONTOGRAPHICAL SOCIETY.

INSTITUTED MDCCOXLVIL,

LONDON :

MDCCCLXIY.

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PORTA

A MONOGRAPH

OF

ala ae es A ae a

DEVONIAN BRACHIOPODA.

BY

THOMAS DAVIDSON, ESQ., F.R.S., F.G.S.,

ETC. ETC

PART -VI.
FIRST PORTION.

LONDON :

PRINTED FOR THE PALZONTOGRAPHICAL SOCIETY.
1864.

a ed

Mp
J, E. ADLARD, PRINTER, BARTHOLOMEW CLOSE.

A MONOGRAPH

or

BRITISH DEVONIAN BRACHIOPODA.

PRELIMINARY REMARKS.

Brtwexn the Upper Silurian and Lower Carboniferous series of deposits there exists a
very extensive formation, to which the designation of OLp Rep Sanpstonz or Devontan
System has been given. ‘This formation, composed of numerous alternations of sand-
stone (chiefly red), shale, slate, and limestone, is largely developed in several of the
counties of Great Britian, and especially in those of Devonshire and Cornwall, whence
most of the examples of Brachiopoda figured in this monograph have been derived.

In the present monograph on the British Devonian Brachiopoda, I purpose to
commence with illustrating their many and varied forms, and to reserve, until a future
occasion, any remarks upon their local and general distribution. Before, however,
entering into these details, I would direct attention to the following observations of
Professor Ramsay, given in his Anniversary Address to the Geological Society of London,
on the 20th of February, 1863, as being the most recent views published upon the
subject.

“ Devonian Rocks.—Lxcepting that they are arranged in a given order of superposition,
there is little to be said respecting the relation of the fossils to the stratigraphical relations
of the Devonian rocks of the south-west of England. When, many years ago, that area
was mapped, extreme analyses in geological surveying had scarcely been introduced ; and
in that country, consisting so largely of granite and gneiss, contorted greywacke and
limestone, no one attempted on maps to split up the Devonian series into distinct sub-

A

2 BRITISH DEVONIAN BRACHIOPODA.

formations. So exceedingly disturbed are the strata, that without a new survey it is to
this day impossible to say what unconformities may or may not exist among its members.
Neither, till the country is remapped, is it possible to make out accurately the exact
zoological relations of the subdivisions ; and the data I now present are only approximate,
being the result of an examination of the Devonian lists with Mr. Salter, who placed his
intimate knowledge of the ranges of Palzeozoic forms at my disposal.

“ First, then, the Devonian fossils are distinct from those of the Silurian rocks of the
district, a circumstance easily accounted for when we know that they lie directly and
unconformably on Lower Silurian strata.

“This, therefore, makes it impossible to prove that in Devon or Cornwall the lowest
Devonian rocks exist. In North America, where such beds lie directly on Upper Silurian
strata, it is plain that the latter suffered extensive erosion before the deposition of the
former, this physical break being accompanied by a marked break in organic succession.
There is thus reason to believe that, if our Upper Silurian strata were in contact with the
Lower Devonian rocks of Devon and Cornwall, the same broken relations would exist
between them ; for of the several hundreds of Upper Silurian forms, it is said that only
about six species occur in the Lower Devonian rocks, perhaps not more than 1] per cent.

“Thus, therefore, we have a zoological break, all but total, between two formations,
accompanied, probably, by a vast lapse of time unrepresented by any strata in Devonshire,
and only possiély represented by the so-called unfossiliferous Lower Old Red Sandstone of
Treland, Scotland, and Wales.

“There being, in Mr. Salter’s opinion, no marked zoological line between our Lower
and Middle Devonian orders, I have massed them, and divided the series as follows :—

“1. Marwood and Pilton beds =the Coomhola Grits of Mr. Jukes and Carboniferous
Slate of Sir R. Griffith.

“©2. Upper Devonian strata.

“3. Middle and Lower Devonian.

“The result of an elaborate analysis from tables prepared for the purpose, is that of
known Middle and Lower Devonian fossils there are about 61 genera and 170 species ;
and of these about 23 species only pass into the Upper Devonian division, or about 133
per cent.

“The Upper Devonian beds yield about 30 genera and 70 species; and of these 24
(or about 34 per cent.) pass into the Marwood beds, which in Devonshire have heretofore
given about 31 genera and 65 species, of which 14 species, or about 21 per cent., pass
imto the Carboniferous rocks. Judged by the imperfect data of mere per-centages, it
appears, then, that the Upper Devonian are less intimately connected with the Lower
Devonian than with the Marwood beds, and that the Marwood beds are zoologically more
nearly related to the Upper Devonian than to the Carboniferous strata. In the south-west

PRELIMINARY REMARKS. 3

of Ireland the Coomhola grits and Carboniferous slate pass downwards into Old. Red
Sandstone, and upwards into Carboniferous Limestone; and they are considered by Mr.
Jukes either to be the lowest part of the Carboniferous series, or else to form a distinct
group together with the upper half of the Irish Old Red Sandstone, which is stratigraphi-
cally quite unconnected with the lower half. Further, it must be remembered that for
many years, in Devon and Cornwall, Silurian and Devonian rocks were all massed together
and called by one name. But we know that there must be an unconformity discoverable
between the Lower Silurian and Devonian rocks, if properly searched for; and analogy
would lead us to expect, from the strong breaks in organic succession, that the same
broken stratigraphical relations—lapses of unrepresented time—must exist between the
various members of the typical Devonian series, just as they certainly occur in what
geologists consider their equivalents, the Old Red Sandstones of Scotland and of Ireland.”*

Mr. Pengelly, whose knowledge of Devonshire and Cornwall Devonian Geology is very
considerable, informs me that, according to Professor Sedgwick’s system, (‘ Quart. Journ.
Geol. Soc.,’ vol. viii,) the slates aud limestones of North Devon and Cornwall, as those
of Looe, Woolborough, Ramsleigh, Hope’s Nose, Glampton Creek, Galmpton Point, Black
Hall, St. Veep, Polruan, and Whitesand Bay, belong to the lowest Devonian group found
im the two counties ; that he followed him in his paper on the distribution of the fossils of

1 The late D. Sharpe, writes in June, 1852 (‘ Journ. Geol. Soc.,’ vol. ix, p. 22), that he urged Mr. Morris,
in 1843, to separate from the Devonian system the fossiliferous beds of Pilton and Barnstaple (and,
perhaps, Marwood) in North Devon, and those of Tintagel and South Petherwin in the South, and to
place them in that group of strata which corresponds to the Lower Limestone-shales of Northumberland
and the Scotch coal-field.

Mr. Salter thus classes the North Devon strata in descending order.

I. Prrron Beps.—An alternating series of calcareous sandstones and grey shales, with their bands
cf limestone and grey slate, full of fossils, several hundred feet thick.
II. Marwoop Brps.—A thick series of greenish-grey grits, with bands of Cuculea and Avicula in
abundance, with olive slate in which a Lingula occurs plentifully (both Mr. Salter and Sir
H. de la Beche make the Lingula-beds to be older than the Pilton group), they run parallel
with, and in close proximity to the Cuculea-beds.
Ill. Morre Grovr.

No Devonian Brachiopoda have been found in Scotland. The Dron Shales form a small patch in
Lower Strathearn, dipping southwards into the base of the Ochils and towards the coal-fields of Fife, but
separated by the entire breadth of the Orchils and the Old Red plains of 8S. Watheden. Mr. D. Page,
Professor Harkness, Mr. Salter, Mr. Powrie, Professor R. Jones, Mr. Etheridge, and myself, are inclined to
regard them as Lower Carboniferous, and not Devonian, as some have supposed. ‘hey contain but a
single species of Brachiopoda, which appears referable to Rhynchonella pleurodon: the other organisms,
although generally very imperfectly preserved, are of a Carboniferous type, Leperditia subrecta (Portlock’s
Cypris subrecta), a common Lower Carboniferous fossil, having been also recognised by Mr. Jones.

The Devonian formation is largely represented in Ireland, and especially in the southern portion of
the island; but, with the exception of a few localities wherein plants, fish-scales, and Anodon Jukesii have
been found, it is non-fossiliferous, and I have not heard of any Brachiopod having been hitherto met
with.

4 BRITISH DEVONIAN BRACHIOPODA.

Devon and Cornwall, in the ‘ Geologist,’ vol. v, p. 10, &c., but that neither Professor
Sedgwick nor himself intend by this to express any opinion respecting the co-ordination of
these Devonian rocks with those of the Devonian system elsewhere. Mr. Pengelly would,
however, arrange the localities represented by the fossils he sent for my examination as
below, in descending order :— .

Barnstaple, Bagey, Tintagel 2»; «. ..s'...00xess0s0e Transition or Devonian-Carboniferous Beds,
Dintagel ( Petherwiit x. xsosscuseclususeicms- sorkenne: Upper Devonian of Devon and Cornwall,

L ton, Woolb oh, Ramsleigh ?, Hope’ oie :
sapear a ap hgh tan tage “st ES Middle Devonian of Devon and Cornwall,
Nose ?, Galmpton or Warren Point .........

Looe, Meadfoot, Galmpton Creek, Black Hall, | Lower Devonian of Devon and Cornwall = Upper
St. Veep, Polruan, Whitesand Bay ......... Old Red of Scotland,

but that he would not be surprised to find the Hope’s Nose beds belonging somewhat
higher ; that Ramsleigh, though very near Woolborough, has little in common with it. It
certainly yields in great plenty the coral Acervularia pentagona, which Murchison marks
a characteristic fossil in his “ Middle Devonian,” but, so far as he knows, this organism is
not found elsewhere in the district; moreover, the Upper Silurian coral, Chonophyllum
perfoliatum, occurs at Ramsleigh but in no other Devonian locality, so the locality is rather
a puzzling one.

Professor L. de Koninck considers that the Torquay beds correspond to the psam-
mites of the Rhine, while those of Newton would represent those of the Eifel. The
Devonian formation is therefore composed of a very remarkable series of deposits,
which have attracted much interest in this country as well as upon the Continent and in
America, and been the subject of many important researches and works by some of our
most able geologists and paleontologists, among whom we may mention Sir H. De la
Beche, Sir R. Murchison, Sir C. Lyell, Professors Phillips, Sedgwick, M‘Coy, Schnur,
Hall, and Jukes; Viscount d’Archiac and M. De Verneuil; Drs. Sandberger, Messrs.
Godwin-Austen, Lonsdale, Pengelly, Weaver, Kelly, Sowerby, H. Miller, Salter,
Schlotheim, I’. Roemer, Baron Von Buch, and others, whose labours and works will be
alluded to in the sequel.

The material I have been able to examine in connection with this monograph has been
considerable, but has not always been so good in quality as in number of specimens ; and this
may be easily accounted for when we remember how many of our Devonshire and Cornwall
fossils have been contorted and put out of shape from the effects of cleavage and pressure,
and that a large proportion of the fossils are found in the state of imperfect imternal casts,
or obscure fragments and impressions, at times completely undeterminable. It is in the
limestone of the Middle Devonian, especially from the neighbourhood of Newton Abbot,
‘Torquay, Plymouth, and some other localities, that our most perfect specimens have been
obtained ; and it is a most pleasing duty to again return thanks to Sir R. Murchison and
Professor Huxley for the use they have kindly enabled me to make of the valuable series of
specimens preserved in the Museum of the Geological Survey of Great Britain, and where

PRELIMINARY REMARKS. 5

a large proportion of the specimens described by Phillips in his work on the Paleozoic
Fossils of Cornwall, Devon, and West Somerset, have been carefully preserved. I am also
greatly indebted to the Council of the Geological Society of London for the loan of their
valuable series of Devonian fossils, which were collected by Sedgwick and Murchison,
De la Beche, Hennah, D. Sharpe, &c., and which have been partly described and figured
by J. Sowerby in the fifth volume, second series, of the ‘Transactions of the Geological
Society.’ I wish also to record my thanks to the officers of the Geological Department of
the British Museum, for having allowed me to examine and draw those specimens which were
required for the present monograph. Much, however, of the material was contributed
from private museums. ‘To Mr. Pengelly my thanks are due for much valuable information,
as well as for the loan of his extensive series of Devonshire and Cornwall Brachiopoda.
To the Rev. J. E. Lee, of Caerleon, I am indebted for the loan of his important series of
Barton Middle Devonian fossils, and in which are preserved many of the original specimens
described and figured by Phillips in the work already named. My sincere thanks are
likewise due to Mr. R. Stewart, Hon. Sec. of the ‘Torquay Natural History Society ; to
Mr. Vicary, of Exeter; Mr. Champernowne, of Dartington Hall, Totness, Devonshire ; to
Mr. W. Walton, of Bath ; Mr. C. Spence Bate, of Plymouth ; Mr. R. H. Valpy, of Ilfracombe ;
Mr. F. M. Hall, of Barnstaple ; Mr. Symons, of Braunton ; the Rev. F. Mules, of Marwood ;
Professor Phillips, of Oxford; Mr. Salter, and others, for much information and the loan of
their fossils. Many specimens are also preserved in the Cambridge Museum, as well as in
the museums of different local institutions in Cornwall and Devonshire, such as that of
Taunton, which contains the collection of the late Rev. D. Williams, the Bristol Institution,
that of Plymouth, Torquay, Truro, &c. I am also greatly indebted to Professor L. de
Koninck, F. Roemer, and to Mr. Bouchard, for the comparison they have kindly made of
some of our British Devonian species with those of the Continent.

Before proceeding further, it may be as well to mention that in the last edition of
Professor Morris’s ‘Catalogue of British Fossils,’ published in 1854, some ninety-four
species (?) of British Devonian Brachiopoda have been enumerated, but it will be found
by the sequel that a certain number of these will have to be located among the synonyms,
and that some other important new or well-known foreign Devonian forms, such as Uncites,
Gryphus, Davidsonia Verneuilii, Atrypa lepida, &ec., will require to be added to our British
catalogue. I must not, however, attempt to conceal that I have experienced great difficulty
and uncertainty relative to the identification of some of these so-termed species, chiefly from
the want of sufficiently perfect material, and, at times, insufficiency of description and illus-
tration by several original describers. In these cases I have reproduced the original
descriptions and figures, and have prefixed a point of interrogation to each description
where some doubt may prevail, or where the material has not been quite sufficient to
warrant a satisfactory determination.

I will not at present anticipate what I may have to say with reference to those species
which are common to the Silurian, Devonian, Carboniferous, and Permian systems, as I

6 BRITISH DEVONIAN BRACHIOPODA.

shall endeavour to treat that question in the concluding portion of this monograph, but
will, without further observations, proceed with the description of the species we have been
able to assemble.

Famly—_TEREBRATULID A.
Genus—TEREBRATULA, Llhwyd.

TEREBRATULA SAccULUS, Martin; variety? PI. I, fig. 1—8.

ANOMITES SAccULUS, Martin. Petref. Derbesiana, tab. xlvi, figs. 1 and 2, 1809.
— — Dav. Mon. Carb. Brach., p. 14 and 213, pl. i, figs. 23, 24, 27, 29, 30.
TEREBRATULA SACCULUS, Phillips. Palzeozoic Fossils of Cornwall, Devon, and West Somer-
set, p. 9], tab. xxxv, fig. 166, 1841.
—_ HASTATA. Ibid., fig. 168.
— vireo, Ibid., fig. 167.
—_ saccuLus, A. Roemer. Die Versteinerungen des Harzebirges, pl. xii, fig. 23.

Specific Character—Shell ovate, or imperfectly pentagonal, front margin straight,
rounded, or slightly emarginated, valves almost equally and evenly convex, with or
without a small depression near the front in the central valve, beak slightly produced and
truncated by a small circular foramen: beak-ridges more or less defined. Surface
smooth. Proportions variable. Two British specimens have measured

Length 10, width 8, depth 5 lines.

PP RIO SS Jap SIMS OS Fe

Observations.—W hile describing the Terebratulee from the Middle Devonian Limestone
of Barton and Lummaton, near Torquay (Z! juvenis excepted), Professor Phillips appears to
have laboured under the same difficulties and uncertainties I now experience in the
identification of these very variable shells. These Barton Terebratule are divided by
Phillips into three so-termed species; those that are oblong-ovate with a straight or
emarginated front he identifies with 7! sacculus ; those that are ovato-lauceolate, uniformly
convex, with a prominent beak, and contracted nearly straight front margin, he terms
7. virgo; while others are believed by him to resemble young specimens of 7. hastata
from the Mountain-limestone. It would not, however, be correct to admit three distinct
species out of so variable a shell, and especially so, when in a handful of specimens every
gradation of shape can be found connecting the three extreme conditions described by
Phillips. At p. 214 of my Carboniferous Monograph, I entered into many details in

TEREBRATULA. ree 7

order to show the apparently very close connection existing between all our hitherto dis-
covered British Carboniferous and Permian Terebratulae, and which are in all probability
mere variations in shape of a single species, and it is my impression that the Devonian
form above described is nothing more than another slight modification of the Carboniferous
species, or, in other words, that both the Carboniferous and Permian shells are
derived from, or are mere slight modifications of the Devonian one above described. Mr.
Bouchard is, however, of opinion, that figs. 1 to 8 of our plate should be referred to
Scholtheim’s Zer. elongata, a form found in the Permian strata of England and of the
Continent, as well as in the Devonian Limestone of Grund in the Hartz; at Ferques, near
Boulogne, and in that of the Eifel, I am quite ready to admit with Mr. Bouchard, that
some of our Barton and Lummaton specimens do exactly resemble young examples of
T. elongata, which have both valves convex, and a nearly straight front line; but it must
also be remembered that in adult and well-shaped specimens of Schlotheim’s species the
ventral valve presents in profile a regularly arched curve from the extremity of the
beak to the front, with a wide depression or shallow simus, commencing towards the
middle of the valve and extending to the front, producing in the frontal margin a convex
and elevated curve, varying in degree according to age and individual, but which is not
the usual aspect of Barton and Lummaton species. It appears to me probable that the
shell under description will be more correctly located with Z. sacculus, and of which
T. hastata and 7. Gillingensis are vavieties, for many of our Lummaton specimens exactly
resemble each of these modifications, and which we consider to belong to a single species.
I should also mention that Mr. Carrington has recently discovered several examples of
T. sacculus with colour-bands similar to those we have described in 7. hastata, so that
one of the objections brought forward by some paleontologists to the uniting of those two
so-termed species is now removed.

It is quite evident that Schlotheim originally applied the name of 7" elongata to the
Permian form, but that subsequently he referred some Devonian specimens to his Permian
type, and I have shown in Pl. 54, figs. 1—4 of my Carboniferous Monograph, that many
specimens of the Carboniferous 7. /astata and the Permian 7. elongata are undis-
tinguishable.

From these considerations I quite coincide in the opinion expressed by Mr. Bouchard,
that it would be only encumbering science with another useless synonym were we to
give to the Devonian form a separate specific designation, and as that of Sacculus
is the oldest on record, it would I think be prudent to make use of it in the
present instance. 7! sacculus has been also found in the Middle Devonian Limestone of
the neighbourhood of Plymouth, and in the Upper Devonian (?) brown grits of Pilton and
Marwood in Devonshire.

8 BRITISH DEVONIAN BRACHIOPODA.

? TeREBRATULA ELONGATA, Schlotheim. PI. I, fig. 9.

TEREBRATULITES ELONGATUS, Schloth. Akad. Miinch., vol, vi, pl. vii; figs. 7—14, 1816;
and Nachtragen zur Petrefactenkunde, pl. xx, fig. 2,
1822.

Some internal casts of a Terebratula, resembling specimens of 7. elongata, from our
British Permian shell-limestone, have been found in brown grits of the Upper Devonian (?)
(Pilton and Marwood series) of East Hill, Braunton, North Devon.

TEREBRATULA JUVENIS, Sow. PI. I, figs. L1O—15.

ATRYFPA JUVENIS, Sow. Geol. Trans., 2d ser., vol. v, pl. 56, fig. 8.
TEREBRATULA JUVENIS, Phillips. Figures and Descript. of the Paleozoic Fossils of Corn-
wall, Devon, and West Somerset, p. 90, pl. xxxv, fig. 165, 1841.

Spec. Char. Shell ovate, as broad as, or longer than wide, contracted in front, widest
near the beak. Ventral valve deep and uniformly convex; beak wide, rounded, and
much incurved; foramen minute, contiguous to the umbone; lateral ridges angular ;
forming -well-marked curves on either side. Dorsal valve nearly flat, or shghtly convex,
sometimes rather depressed in the middle and at the front ; surface smooth, marked only
by lines of growth. Proportions variable.

Length 7, width 6, depth 4 lines.

Fo, gee Os. Bd “OAs
Fei A Oa 85. Dam 90 o> Oh aap

Obs. This Terebratula is remarkable on account of the great difference observable in
the respective convexity of its valves; the dorsal one being perfectly flat in young
examples, and but slightly convex even in adult individuals, whilst at all ages the ventral
valve is deep and very convex. The shell is also characterised by a peculiarly shaped
beak, which looks as if it had been compressed so as to touch and overlie the umbone,
which leaves a flattened space between its angular beak-ridges and the hinge-line. The
interior is unknown, but the loop was in all probability short and simple.

7. juvenis abounds in the limestone of the Middle Devonian of Barton and Lummaton,
near 'l'orquay. The original type described by Sowerby was derived from similar beds
near Plymouth, and is now preserved in the museum of the Geological Society of London.

TEREBRATULA? Nuwtonrensis, Dav. PI. IJ, figs. 16, 17.

Spec. Char. Shell slightly pentagonal, valves almost equally deep, and moderately
convex, depressed or flattened along the middle near the front ; beak not very prominent,

i

TEREBRATULA. 9

with well-marked lateral ridges in either valve, continued along the sides without incurving
to join the hinge and lateral margins, and leaving a concave, subparallel space between
them and the hinge-line; foramen minute, completed by a deltidium; surface smooth.
Dimensions variable; length 12, width 13, depth 5 lines.

Obs. Of this species I have seen three or four examples derived from the Middle
Devonian limestone of Lane’s or Woolborough quarry, near Newton Abbot, in Devonshire ;!
but, from not having been able to examine its internal dispositions, [am uncertain as to its
genus, and have, therefore, provisionally located it under 'lerebratula. In external shape,
T. Newtoniensis bears much resemblance to the Jurassic Waldheimia numismalis ; but it
might perhaps belong to Prof. Suess’s sub-genus Meganteris. The thickening or emargina-
tion of the valves is very great in some specimens, reminding us of what is sometimes seen
in Zerebratula carinata. One large example in the collection of Mr. Vicary came to hand
too late to be figured in its proper place.

T. Newtoniensis occurs also in the Devonian limestone of Néhou in France, from
whence I obtained two examples.

1 Mr. Pengelly informs me that there are various limestone-quarries, all more or less good fossil-
localities, in the neighbourhood of Newton Abbot (Newton really consists of two towns, Newton Abbot
and Newton Bushell, separated by a small stream), namely, Woolborough, Ramsleigh, Ogwell (2 or 3),
Bradley (2), and all spoken of by strangers, and even by resident collectors, under the common term
“Newton ;” it is therefore desirable, where possible, to mention the exact locality, as some species occur in
one place which are not found in the others. ‘The same may be said with reference to Torquay and its
neighbouring localities, Barton, Lummaton, Hope’s Nose, Meadfoot, &c. Barton and Lummaton quarries
are among the richest spots we are acquainted with, and are situated at about two miles’ distance from
Torquay. The village of Barton lies between them; Phillips, and all other strangers, would in all proba-
bility call both “Barton.” The Lummaton quarry is at the north-west extremity of the mass of lime-
stone which forms a great part of the Torquay peninsula. Barton quarry is in an outlier of the same, and
is separated from it, perhaps, about three furlongs, the intermediate vale being occupied by the Devonian
slate, which underlies the limestone. I have no doubt, from the similarity of many of the fossils, that both
Barton and Lummaton are on the horizon of the Woolborough beds. Hope is frequently mentioned by
Phillips; it should be Hope’s Nose, the northern extremity of Torbay. This is again a limestone outlier,
a relic which, like sundry islets in Torbay, testifies to a vast amount of denudation; the strata are well
marked, but greatly contorted and cleaved, and occasionally unconformable, so that the fossils are but
rarely well preserved. The Woolborough limestone is a very curious deposit ; some parts of it have a very
metamorphosed aspect, and very frequently the change is so very sudden that small hand-specimens appear
like parts of different rocks. Occasionally, moreover, the quarrymen suddenly break into small cavities
containing an almost black, unctuous powder, in which our best fossils occur. This powder contains a
considerable amount of iron. Many of the limestones contain silex, This quarry is mentioned by the
late Sir H. De La Beche, under the name of ‘‘ Newton Quarry,” as remarkable for the number and variety
of the fossils it has yielded, Mr. Godwin-Austen having found no fewer than 139 species (see ‘Memoirs
Geol. Survey,’ vol. i, p. 88). Ramsleigh is about half a mile from Woolborough, and belongs to the great
mass of Ogwell, Ipplepen, and Denbury limestones. There are also several distinct localities in the neigh-
bourhood of Plymouth, &c., which should be carefully noted.

10 BRITISH DEVONIAN BRACHIOPODA.

Sub-genus—ReEnssELaRiA, Hall.
RENSSELERIA STRINGICEPS,’ var.? LF. Roemer (sp.). Pl. IV, figs. 5; 6, 7.

TEREBRATULA STRIGICEPS, F. Roemer. Rhein. Uebergangsgeb., p. 58, tab. i, fig. 6, 1844.
— — Ibid. Schnur, in Dunker und Von Meyer’s Palzonto-
graphica, vol. ili, p. 183, tab. xxv, fig. 2, 1853.
RHYNCHONELLA — Sandberger. Die Brachiopoden des Rheinischen Schichten-
Systems in Nassau, p. 41, pl. xxxii, fig. 14, 1855.

Spec. Char. Shell oval, elongated ; valves almost equally convex, without fold or sinus ;
beak much incurved and pointed ; surface of valves covered with numerous small radiating
ribs, which increase in number by the intercalation of additional ones at various distances
from the beak. Proportions variable ; length 12, width 9 lines.

Obs. Of this interesting species I can offer but an incomplete description, on account
of the very imperfect material at command, consisting of casts and impressions,
chiefly of the ventral valve, discovered by Mr. Valpy in the Middle (?) Devonian limestone
of Hagginton Hill, near Ilfracombe. Having compared these casts with others of 7.
stringiceps from the Eifel, I could discern no valid ground for the creation of a separate
species, and will, therefore, at any rate provisionally leave our British specimens under the
specific name of striagiceps. Iam also somewhat uncertain as to the genus to which
these casts should be referred ; but cannot, I think, be very far mistaken while provisionally
leaving them with Rensseleria, a sub-genus proposed by Professor Hall for a set of shells,
such as &. Swessana and £2. ovoides, and which appear to nearly agree in general character
with &. stringiceps. Professor Hall describes his sub-genus as follows: —‘“ Shell inequivalved,
oval, ovoid or suborbicular, elongated or rarely transverse, generally gibbous or ventricose ;
valves more or less convex, without mesial fold or simus; beak prominent, acute, more or
less incurved ; foramen terminal, sometimes concealed; . . . surface radiatingly striated, or
finely plicated, rarely smooth;’” all which would agree with the description we have
given of the exterior characters of 2. stringiceys. ‘The muscular impressions resemble
those observable in Rensseleria, but nothing further can be said relative to the interior
dispositions, although we have reason to suspect that they must be similar to those de-
scribed by the American paleontologist, and which consist of an elongated loop not
unlike that so well described by Professor Suess in Meganteris, to which the sub-genus
Rensseleria, if not a synonym, is at any rate very nearly related.

ft. stringiceps has been obtained from the Lower Devonian beds of the Rhine, in
Nassau, &c.

Roemer spells this name Strigiceps, but it ought by right to be Stringiceps, in accordance with the
Greek genitive, as Stringocephalus.

ae Twelfth Annual Report of the Regents of the University of the State of New York,’ p. 38, 1859.

STRINGOCEPHALUS. 11

Genus—StRINGOCEPHALUS, Defrance.

SrrincocerHatus Burtini, Defrance. PI. I, figs. 18—22; Pl. Il, figs. 1—11.

Srrycocepnatus Burtini, Defrance. Dic. des Sciences Naturelles, vol. li, p, 102, et Atlas,
pl. Ixxv, figs. 1, 1%, 1827.
TUREBRATULA PORRECTA, Sow. Min. Con., pl. 576, fig. 1, Nov., 1827.
SrRIGocEPHALUS Burtint, Blainville. Malacologie et Conchyliologie, p. 511, t. liii.
TEREBRATULA STRIGOCEPHALUS, VY. Buch. Ueber Terebrateln, p. 117, 1834.
STRIGOCEPHALUS GIGANTEUS, Sowerby (Terebratula gigantea, Sow., Encye. Metropl.),
Trans. Geol. Soc. of London, vol. v, 2nd series, pl. lvi,
figs. 10, 11, 1837-39.
StryGocePHALus Burtini, D’ Archiae et De Verneuil. Description of the Fossils in the
Older Deposits of the Rhenish Provinces; Trans. Geol. Soc. of
London, 2nd series, vol. vi, p. 393, 1840.
— porsatus, De Vern. (Strygocephalus dorsalis, Goldf., Bonn Mus.).
Ibid., p. 369, pl. xxxv, fig. 5, 1840.
STRIGOCEPHALUS Burttni, Phillips. Figs. and Descrip. of the Paleozoic Fossils of Corn-
wall, Devon, and West Somerset, p. 79, fig. 141, 1841.
— GIGANTEUs. Ibid., p. 80, fig. 142.
SrrincocupHatus Burtini, F. A. Roemer. Beitrage zur Kenntness des Nordwestlichen
Harzgebirges in Dunker u. V. Meyer’s Palzeontographica,
vol. iii, p. 24, pl. x, fig. 2, 1850.
Uncrtes Lavis, M‘Coy. British Paleozoic Fossils, p. 380, pl. ii a, fig. 6, 1852.
SrrincocerHaLus Burrini, Sehnur. Beschreibung Eifel. Brachiopoden, p. 195, pl. xxviii,
fig, 55 pl. xxix, fig. 1; pl. xxxi, fig. 1, 1853.
= — Davidson. Introduction, p. 73, pl. vii, fig. 98, and French
Ed., Mém. de la Soc. Linnéenne de Normandie, vol. x, p. 74,
figs. 45—50, 1856.
— — Suess. Zur Kenntniss Stringocephalus Burtini, Verhandl. d. z.
b. Vereins, iii, 1853, and German Ed. of Davidson’s Intro-
duction, pl. i, fig. 16, 1856.
— HIANS, Sandberger. Die Brachiopoden Rheinischen Schichtensystems in
Nassau, p. 31, fig. 4, 1859.

Spec. Char. Shell very variable in shape, suborbicular, transversely or longitudinally
oval ; valves usually either evenly convex, without fold or sinus, or with, sometimes, a more
or less distinct median groove upon each valve. Ventral valve usually somewhat deeper
than the ventral one; beak incurved, more or less prominent, entire and pointed at its
extremity ; hinge-area distinct, and in the young age divided by a large fissure, which
becomes with age gradually surrounded by the deltidium, so as to become oval, and even
sometimes finally closed, in some adult individuals. External surface smooth, and, when
perfectly preserved, covered with very fine, delicate, slightly undulated, longitudinal
strie. Valves articulating by means of a large prominent tooth situated on either

12 BRITISH DEVONIAN BRACHIOPODA.

side at the base of the deltidium, close to the hinge-line, and fitting into corresponding
sockets in the smaller valve. In the interior of the ventral valve a large, mesial, longi-
tudinal septum extends from the extremity of the beak to within a short distance of the
frontal margin. This plate is thick at its origin and base, but gradually decreases in width
while increasing in depth as it recedes from near the extremity of the beak. In the
smaller or dorsal valve a massive, curved, very prominent cardinal process stretches to the
opposite valve, where it clasps the ventral mesial septum with its forked extremity. Near
the base of this process in the dorsal valve a longitudinal septum arises, smaller than that
of the ventral valve, and divides the quadruple impression of the adductor-muscle; the
socket-walls are very much expanded, forming prominent hinge-plates curving inwards
on each side of the cardinal process. ‘The lower portion of the hinge-plate supports a
shelly loop in the shape of two flattened stems or lamellae, which, after proceeding with a
slight upward curve to near the extremity of the septum, are suddenly reflected, and again
approach the sockets before sweeping submarginally round in the shape of a large, wide
loop, from the inner edge of which a number of smaller lamella branch off and converge.
Shell-structure punctate. Dimensions variable ; some examples have attained five or six
inches in length by something less in width, but the generality of specimens have smaller
proportions.

Obs. ‘This very interesting and characteristic Devonian species has been the subject
of much investigation ; and although its internal arrangements were partially known since
many years, it is to Professors King and Suess that science is mainly indebted for the
knowledge we now possess of the calcified supports of the labial appendages. Like many
of its congeners, it has been shifted about from genus to genus, and has received several
specific denominations ; but palzeontologists have now very generally agreed to retain for
it the generic and single specific denomination Stringocephalus* Burtint.

Professor Suess, in his excellent paper, ‘ Zur Kenntniss des Stringocephalus Burtini,
states that, if one discards the very doubtful figure in Schlotheim’s ‘ Petrefactenkunde ’
(p. 260, pl. xvi, fig. 4), it is Defrance who was the first to name and describe the
species. In the month of November of the same year Sowerby published a description
and figure of the same shell from Bradley, under the name of Zerebratula porrecta.

To varieties also of this species Hoeninghaus and Goldfuss have given two catalogue-
names, Sérig. clongatus and Strig. striatus ; and in the ‘ Encyclopedia Metropolitana’
Sowerby described and figured some large, flattened, and distorted examples of Séring.
Burtini from Plymouth, under the denomination of TZerebratula gigantea and 7.
LTennahiana (sce likewise ‘ Geol. Soc. Trans.,’ 2 ser., vol. v, part 3, Explan. of plates).

1 The etymology of Defrance’s term Strygocephalus has been the theme of some difference in opinion.
Dr. Sandberger appears to have been the first paleontologist who wrote the name Stringocephalus (in
Leonhard und Bronn’s ‘ Jahrb.,’ 1842). The term sérix, sometimes from corruption written séryx or struz,
means a screech-ow] (orpi£, genitive orpryyos, stringos), and is no doubt the meaning intended by Defrance,
although he spelt the name erroneously.

ATHYRIS. 13

Strig. dorsalis, D’ Archiac and De Verneuil, is a variety having a more or less distinct
median groove upon each valve, this groove being prolonged to the beak of the ventral
valve and only to about the middle of the dorsal one. It is, however, a mistake to suppose
that it is only this variety which has its surface covered with delicate, longitudinal striae,
for I have observed the same on some well-preserved German specimens which had no
groove in either valve.

Stringocephalus Burtini has assumed many shapes and degrees in the projection and
incurvature of its beak, and Professors De Koninck and Suess, who have along with
myself examined the original example of M‘Coy’s Uncites levis (Pl. II, fig. 9, of this
monograph), have expressed it to be their opmion that the last-named shell is nothing
more than an exceptional, much elongated example of Defrance’s String. Burtint.

Stringocephalus Burtini is a characteristic fossil of the Middle Devonian limestone or
“« Stringocephalen-Kalk” of the Germans. In England it occurs in South Devonshire
at Plymouth ; Bradley, near Newton; and Chircombe Bridge, near Ogwell. In North
Devon at Combe Martin and Hagginton. Mr. Valpy states that he found a specimen
in the limestone of Ilfracombe.

On the Continent it is very abundant at Paffrath, near Cologne, at Villmar, and in the
Eifel ; also at Diete, Brilon-upon-the-Lahr, and at Chimay and Nimes in Belgium, &c.

Family—SPIRIFERID Al.
Genus—Arnyris, M‘Coy,;’ vel Spiriamra, D’ Ord.

1 In 1853, while publishing my ‘General Introduction’ in the first volume of the present work, I
proposed to apply the term Athyris, M‘Coy, to shells such as dtrypa tumida, Dal., and Terebratula
Herculea, Bar., and to make use of D’Orbigny’s better name Spirigera for those species with a perforated
beak, such as Athyris concentrica. This view or substitution of names and shells was subsequently objected
to, it being justly considered that as M‘Coy’s generic designation of Athyris was intended for shells such
as dA. concentrica, that it could not be correctly applied to another group of species. Therefore, much to
my regret, but in order to adhere to the Jaw of priority, I subsequently restored to Athyris 4. concentrica
and its congeners, and made use of Merista for those to which I had, in 1853, applied the term Athyris.
I believe, however, that with time the term Athyris will be completely disused, and that of Spirigera
preferred, as the law of priority should not be allowed to perpetuate a palpable zoological misnomer. Mr.
R. Jones is of opinion that generic, being group names, may be improved upon (see his ‘Monograph on
Estherie,’ p. 11, note).

In the ‘Thirteenth Annual Report of the Regents on the State Cabinet of New York,’ published in
1860, Professor Hall makes some interesting observations on the subject, which we will transcribe, as
being little known in this country.

“Among the fossils referred for many years to Terebratula, Atrypa, &c., European authors have
separated the genera Athyris and Merista, shells which have many characters in common, and which
were, indeed, at first united under Spirigera or Athyris, until in 1851 the genus Merista was proposed by
Professor Suess. In my later studies of the Brachiopoda of the American Paleozoic strata, I have referred
to the genus Athyris certain species which have a subglobose or ovoid form, with lamellose surfaces, and

14 BRITISH DEVONIAN BRACHIOPODA.

Atuyris concentrica, You Buch (sp.), 1839. Pl. III, figs. 11—15, and 24.

TEREBRATULA CONCENTRICA, Von Buch. Ueber Terebrateln, p. 103, Berlin, 1834; and
Mém. Soe. Géol. France, vol. iii, p. 214, 1839 (described,
but not figured).

without or with scarcely perceptible radiating strize; while other forms, which are less distinctly lamellose,
and always more or less distinctly radiatingly striate, with fine concentric lines of growth, I have referred
to the genus Merista. Many of the latter have the general form and surface-characters of Merista
(4trypa) tumida, Dalman, but are less ventricose ; they all have internal spires, and when perfect, the
beaks appear to be imperforate. ‘The radiating striee, though visible in well-preserved specimens, are still
more conspicuous in the partially exfoliated shell. dtrypa tumida of Dalman is cited by Davidson as one
of the types of the genus Merista.

‘IT proposed last year (‘Twelfth Report of the Regents’) a separation of certain Merista-like forms
under the name of Camarium, on account of the presence of an arching transverse septum in the ventral
valve. Subsequently a more careful consideration of the characters of Merista, as given by Mr. Davidson, and
an inspection of his figures, have shown me that the arching septum, in its attenuation towards the beak, is
identical with the shoelifter process described as belonging to the genus Merista. An examination of numerous
specimens of different species of those which I have referred to the genus Merista shows no evidence of
this process or septum, and the deep muscular impression below the rostral cavity, and the thickening of
this part of the shell, are characters incompatible with the existence of the septum. Moreover, I conceive
that this arching septum, or the extension of the shoelifter process into the cavity of the valve, would
produce such a modification of the soft parts of the animal, that the inhabitants of these shells were
generically distinct from the inhabitants of the large uninterrupted cavity of the shells which heretofore I
have referred to Merista.

“In order, if possible, to reach a solution of the question, I have had the shell removed from a solid
specimen of M. tumida (from Dudley), which is one of the types of the genus, and there is certainly no
evidence of the septum or shoelifter process, but, on the contrary, the presence of all the character-
markings of the American species which I have referred to Meriséa, in vol. iii, ‘Pal. New York.’ At the
same time, the MJerista (Terebratula) scalprum of Barrande [ Herculea of Barrande, or scalprum of
Roemer], in the most solid of the specimens which I possess, really reveals the presence of the septum.

“Since this shoelifter process, or septum, was originally described by Professor Suess as characteristic of
the genus Merista, and the species designated by him as the types of the genus (the ©. sca/prum and
M. Herculea of Barrande) ‘do possess this feature, the genus must be retained for the species with the
shoelifter process.’ (Davidson.)

“It would appear, therefore, that the genus Camarium, proposed by me in the preceding report,
possesses characters identical with Merista, as originally described by Suess, but which have been over-
looked to some extent in consequence of the reference to M. tumida as a typical form of the genus......
At the same time, as the JZ. tumida of Dalman, an English and Swedish species, in common with numerous
well-marked forms in our Silurian and Devonian strata, do not possess this feature, we can no longer with
propriety refer them to that genus.

“With this restriction, the Meriste proper consist of smooth, ovoid, circular, or transverse shells,
with usually a conspicuous sinus upon the ventral valve, and a corresponding wide, often undefined, mesial
fold or elevation upon the dorsal valve ; the hinge-articulation being not very different from that of Athyris,
to which they are allied.

«The interior of the ventral valve, however, is strongly distinctive, and the septum or shoelifter process

ATHYRIS. 15

TEREBRATULA HISPIDA, Sow. Trans. Geol. Soc., 2nd series, vol. v, pl. liv, fig. 4.
some CONCENTRICA, De Verneuil. Bull. Soc. Géol. de France, vol. xi, p. 251,
pl. ii, fig. 1, 1840.
SprrIGERA CONCENTRICA, D’Orb. Prod., vol. i, p. 98, 1849.
ATHYRIS CONCENTRICA, M‘Coy. British Paleozoic Fossils, p. 378, 1852.

SPIRIGERA — Dav. General Introduction, vol. i, pl. vi, figs. 65—67, 1853.

TEREBRATULA — Schnur. Beschreibung Eifel. Brachiopoden, in Paleontographica,
vol. iii, p. 3, 1853.

ATHYRIS —_— Morris. A Catalogue of British Fossils, p. 130, 1854.

SPIRIGERA — Sandberger. Die Brachiopoden Rheinischen Schichten-Systems in

Nassau, p. 3], pl. xxxii, fig. 11, 1835.

Spec. Char. Shell usually wider than long, suborbicular, transversely oval, circular,
or slightly subpentagonal, with rounded contour; valves almost equally convex, increasing
in gibbosity with age. When young, the front is evenly rounded, but with age a more or
less developed broad lobe or mesial fold commences at a little further down than the
middle of the valve, and extends to the front, near to which it attains its greatest elevation.
In the ventral valve a sharply defined sinus commences towards the middle of the valve
and extends to the front. Beak tumid, moderately produced, incurved and truncated by
a small circular aperture lying close to the umbone of the opposite valve ; beak-ridges
undefined, surface more or less deeply marked by numerous close, concentric, regular,
imbricating lamine of growth. In the interior of the smaller or dorsal valve the hinge-
plate presents four depressions or pits, and close to the extremity of the umbo a small
circular aperture appears to communicate with a circular tube, which, after originating
under the platform, extends longitudinally and freely with a slight upward curve to about

is not unfrequently shown in the cleavage of the beak of that valve, in solid specimens, where the interior
is inaccessible.

«‘The forms which I have regarded as Merisfa are similar to those above ; but instead of this septum,
or shoelifter process, they have a deeply marked, triangular, muscular area, just below the rostral cavity of
the ventral valve, which is bordered on the anterior side by a callosity of the shell, and on the two other
sides by the strong dental Jamelle. This feature is not conspicuous in Athyris ; the dental lamellze in that
genus are shorter and less strong, and the form of the muscular impression is different. The dorsal valve

of those shells now under consideration has a longitudinal median septum, a feature which is obsolete, or

partially obsolete, in the species of Athyris, In the Camarium or Merista proper the exterior of the ventral
valve sometimes shows what appear to be two diverging septa, somewhat similar to those in the dorsal
valve of Pentamerus, which are the margins of the shoelifter PIOCESS <ieist eo)

“Restricting, therefore, the signification of the genus Merista to such forms as were originally
included by Professor Suess under that name, it becomes necessary to designate those species of similar form,
but without the peculiar appendage of the ventral valve, by another generic term, and I would therefore
suggest the name Meristella, proposed by me last year.” These three genera or sub-genera would therefore
be typified as follows:

1, ArHyris, or SprricerRa. Ex. d. concentrica, A. phalena, &c.
2. MeRISTA. Ex. M. Herculea, M. plebeia = M. sealprum, &e.
3. MERISTELLA. Ex. M. tumida, M. levis, M. bella, &e.

16 BRITISH DEVONIAN BRACHIOPODA.

a third of the length of the valve. ‘To the inner extremities of the socket-ridges are fixed
the spinal processes, with their extremities directed towards the lateral margins of the
shell. The spiral cones are united by a complicated system of lamelle, somewhat as in
A. pectinifera, A. Royssu, &e. No defined septum is observable in this valye, but a rudi-
mentary mesial ridge divides the quadruple impressions of the adductor. In the ventral
valve the dental plates are tolerably developed, while the adductor leaves a small oval scar
towards the middle of the valve, and which scar is separated into two parts by a minute
mesial elevation, under and outside of which are seen the large impressions of the
divaricator muscle. Proportions variable; the largest English specimen I have seen
measured—length 13, width 15, depth 8 lines.

Obs. ‘This species is characteristic of the Upper Devonian strata of France, as well as
of other countries, but does not appear to be very common in Great Britain, if I may so
judge from the very scanty and imperfect material I have been able to assemble.

In Devonshire a few adult but incomplete examples have been found by Mr. Pengelly
im shales at Mudstone Bay. Internal casts showing the muscular impressions have been
met with by Mr. M. Hall in brown grits of the Marwood and Pilton Upper Devonian (?)
series at Orchard quarry, Pilton, one mile north of Barnstaple, and large impressions of
the same shell were found by the same gentleman at Croyde Bay, seven miles west-
north-west of Barnstaple.

A. concentrica has been met with at Hope’s Nose, near Torquay, and in dark-gray slate
at Galmpton Creek, on the River Dart, but usually in a very fragmentary and contorted
condition; and it has also been obtained from the Upper Devonian strata of South
Petherwin, in Cornwall. At page 130 of his ‘ Catalogue,’ Professor Morris mentions that
the shell occurs in the Middle Devonian of Newton and Ogwell, in Devonshire; but
from those places I have not seen specimens.

On the Continent it is a common fossil at Ferques and Néhou, in France; at Refrath
and Gladbach, in the Eifel; at Hiibigenstein, Tchudovo, &c.; but I am not quite certain
whether it has been really discovered in America, notwithstanding that the Athyris (Tere-
bratula) spiriferoides, Eaton, has been referred to .4. concentrica (but with uncertainty),
by M. De Verneuil, Conrad (‘ Ann. Rep. New York,’ pl. m., 1832), and others. In
his ‘Final Report, 4th District, New York,’ p. 198, fig. 5, Professor Hall expresses a
similar opinion to that advocated by M. De Verneuil ; but subsequently, in the ‘ Report of
the Regents of the University,’ p. 118, 1857, he observes that “this species (the Spzrifera
spiriferoides) has generally been referred to the Zerebratula (Spirigera) concentrica of Bronn,
from which it differs in the straightness of its hinge and much less prominent beak. It
also presents other slight but constant differences of form, the broadest part being almost
always a little above the middle, while in Z! concentrica it is generally a little below it (?).
‘The lamelle are likewise more distinctly imbricated in our shell than in Sp. concentrica. A
comparison of the European specimen with the American ones has shown the propriety of
separating them, and of adopting the name given by Eaton in ‘ Silliman’s Journal,’ 1831.”

ATHYRIS. 7

Athyris hispida, Sow. (fig. 24), has been considered by Professors M‘Coy and Morris to
belong to A. concentrica; but not having been able to sce the original example, I can
hardly express a decided opinion upon the subject.

M. Bouchard is of opinion that figs. 11 and 12 of our plate should be considered a
different, but closely related, species; but I have not ventured to separate them from
A. concentrica, to which they appear to me connected by numerous gradations in shape ;
indeed, in a large series of specimens of 4. concentrica from the Eifel, now before me,
some young and old examples appear almost smooth, so fine are the concentric lines and
laminee, while in other specimens of the same dimensions these same lines and lamine
are strongly marked and developed.

Professors M‘Coy and De Koninck have considered Atrypa decussata and A. indentata
(Sowerby) as synonyms of the species under description; but, as I have not been able to
examine the original examples so named, nor any other specimens of these so termed
species, I shall express no positive opinion upon the subject, and content myself by
reproducing the author’s original description and figures.

(Athyris >) Atrypa decussata, Sow. Plate Ill, fig. 17. (Sowerby, ‘Trans. Geol. Soc.,’
2nd series, vol. v, pl. liv, fig. 5.)

“ Subglobose, slightly compressed ; front even, straight ; surface concentrically striated
and decussated ; beak of the lower valve very little prominent, with a triflmg angle on
each side. Zoc., Petherwin.”

(Athyris?) Atrypa indentata, Sow. Plate III, fig. 16. (Sowerby, ‘Trans. Geol. Soc.,’
2nd series, vol. v, pl. liv, fig. 6.)

'l'ransversely obovate, with an indented front ; the edge of the lower valve elevated,
its beak small, prominent.

“The front of this shell appears as if impressed by the finger, whence its name. ‘The
elevation in the margin of the lower valve does not affect the surface of the other. This
may serve to distinguish it from 4. odovata (‘Silur. Syst.,’ pl. viii, fig. 9), to which it
bears a very close affinity.

“ Zoc., Petherwin (with the last, abundant), Barnstaple.”

(Athyris?) Atrypa oblonga, Sow. Plate III, fig. 1. (Sowerby, ‘ Trans.. Geol. Soc.,’
2nd series, vol. v, pl. liu, fig. 6.)

“Oblong-oval, convex, smooth; front produced, elevated; the elevation narrow.

2

Loc., Barnstaple.’

18 BRITISH DEVONIAN BRACHIOPODA.

It- is stated by Professor M‘Coy, p. 378 of his ‘ British Pal. Fossils,’ that this is a
crushed internal cast of 4. concentrica ; but, although I have seen the original specimen
in the Geological Society's Museum, I would not, upon such scanty and unsatisfactory
material, either venture to confirm or infirm the statement given by the distinguished
paleontologist above named.

ATHYRIS PHALENA, Phil. (sp.), 1841. PI. III, figs. 19, 20, 21.

SPIRIFERA PHALHNA, Phillips. Figures and Descriptions of the Paleozoic Fossils of Corn-
wall, Devon, and West Somerset, p. 71, pl. xxviii, fig. 123, 1841.
— HIRUNDO, Phillips? Ibid., pl. xxviii, fig. 122.
TEREBRATULA Hispanica, De Verneuil. Bull. Soc. Geol. France, 2nd ser., vol. ii, p. 463,
pl. xiv, figs. 6, 7, 1845.
SPIRIGERA PHALZNA, Dav. General Introduction, British Foss. Brach., vol. i, pl. vi, fig.
70, 1853.

Spec. Char, 'Transversely elongated, two or three times wider than long, with
rounded cardinal angles. Hinge-line slightly curved, valves moderately convex, with a
wide biplicated fold in the dorsal valve, and wide sinus in the ventral one, bordered by
two rounded ribs ; beak small, incurved and truncated by a small circular aperture ; beak-
ridges tolerably defined, leaving a somewhat elongated flattened space between them and
the hinge-line. External surface regularly traversed by continuous, equidistant, small
ridges or furrows. Dimensions variable, the only two British examples hitherto discovered
measured — :

Length 7, width 16 lines.

95 Seep era ky Game:

Ods. This very interesting species appears to be rare in great Britain, for I have
been able to examine but two imperfect specimens, obtained by Professor Phillips at
Hope’s Nose, near Torquay, and now preserved in the Museum of the Geological Survey of
Great Britain; and indeed but one of these two (a single imperfect ventral valve) was
named Sp. phalena by Phillips, while the second decorticated example received the name
of Sp. hirundo. Both are, however, considered by Professor De Koninck and myself as
belonging to a single species. Sp. phalena occurs plentifully in the Devonian limestone
of Ferrones (Asturias), Spain, from whence M. De Verneuil obtained some examples
which had attained one inch in length by three and a quarter in width. Some short time
afterwards I discovered specimens of the same, but of smaller dimensions, in beds of the
same age (“‘ Rhenane’”’), at Néhou, in France.

ATHYRIS. 19

Atuyris? Barroniensis (n. sp.). Pl. II, fig. 23.

Spec. Char. Rhombic, with rounded angles, wider than long. Valves moderately
and uniformly convex to about half their length, the remaining portion of the
dorsal valve being trilobed, a concave space separating the central from the lateral lobes.
A shallow sinus exists towards the front in the ventral valve; beak not much produced.
External surface smooth, marked only by lines of growth.

Length 2} inches, width 3 inches, depth 1 inch 2 lines.

Oés. Of this remarkable species I have seen but one example, discovered by Mr.
Lee, in the Middle Devonian limestone of Barton, near Torquay. It is not quite perfect,
but by its dimensions and shape is so different from any other Devonian Athyris ? with
which I am acquainted, that I have ventured to give it a separate designation.

ATHYRIS ? (n. sp.?). Pl. IV, fig 4.

We find in the Lower (?) Devonian grits of Looe, in Cornwall, distorted internal casts of
aremarkably shaped shell, which we suppose to belong to the genus d¢hyris, but they are too
imperfect to admit of specific determination. In shape the shell is somewhat transversely
pentagonal, about one inch one line in length, by two inches two lines in width; the valves
are moderately convex, with a shallow sinus in the ventral one; the beak is moderately
produced, and there appears to exist a flattened space between its ridges and the hinge-
line. I cannot venture to propose a specific denomination on such incomplete material,
but better specimens may perhaps turn up now that the attention of collectors will have
been called to the subject. M. Bouchard thinks it might belong to Spirifera curvata, a
common Eifel species; but the obtuse hinge-line appears to me more like that of an
Athyris than of a Spirifera. I may however be mistaken in my appreciation of the matter.

? Arnyris Newrontensis (n. sp.). Pl. III, fig. 22.

Spec. Char. Shell transversely oval, wider than long, valves almost equally convex,
without fold or sinus; beak moderately produced, and truncated by a foramen ;
beak-ridges sharply defined, leaving a flattened or concave space between them and the
hinge-line. External surface smooth, marked only by concentric lines of growth.

Length 1 inch 9 lines, breadth 2 inches 4 lines, depth 1 inch.

Obs. This shell was discovered by Mr. Champernowne in the Middle Devonian lime-
stone of Woolborough quarry, near Newton Abbot, Devonshire.

20 BRITISH DEVONIAN BRACHIOPODA.

Genus—Merisva, Suess.
Menista PLeBEIA, Sov. (sp.), 1837. Pl. IIL, figs. 2—10.

ATRYPA PLEBEIA, Sow. ‘Trans. Geol. Soc., 2 ser., vol. v, pl. lvi, figs. 12, 13.
— LacryMa, Sow. Ibid., fig. 9.
TEREBRATULA suUBCURVATA, Miinster. Beitrage, Heft 3, pl. 14, figs. 4, 5, 6.
SPIRIFERA PLEBEIA, Phillips. Pal. Fossils of Devon, Cornwall, &c., p. 70, pl. xxviii,
fig. 121, 1841.
SPrRIGERA PLEBEIA, D’Orbigny. Prodrome, vol. i, p. 99, 1849.
TEREBRATULA SCALPRUM, Roemer. Das Rheinisch. Uebergangsgeb., p. 68, pl. v, fig. 1,
1844.

Spec. Char. Shell transversely obovate, as wide as or a little wider than long ; valves
moderately convex, with a slightly elevated’ wide mesial lobe or fold, apparent only near
the front of the dorsal valve ; a shallow sinus or depression is visible in the corresponding
portion of the ventral one; beak small, very much incurved ; external surface marked with
close contiguous lines of growth ; proportions variable ; two examples have measured—

Length 9, width 10, depth 5 lines.

Ue yee ane a;

Obs. ‘This common species is very variable in shape, some specimens being wider than
long, whilst others are longer than wide. It is usually almost circular, the mesial
fold never attaining much projection or elevation. <Atrypa lacryma, Sow., of which the
original type is preserved in the Museum of the Geological Society, along with the types
of A. plebeia, appears to belong to the same species as the shell under description, for we
find every intermediate shape uniting them. ‘The generality of specimens have not their
outer shell-surface perfect ; and consequently a longitudinal line is seen to extend along
the smaller or dorsal valve from the umbo to half or, more of its length, denoting
the presence of an interior septum, while two diverging lines extend from the extremity
of the beak to about two thirds of the length of the valve, indicating the presence of large
condyle-plates, to which are fixed the transverse plates, or shoelifter-shaped process, while in
some examples the portion of the matrix between the hinge-plates has dropped out, leaving
a triangular hollow in the shell or cast, as seen in fig. 5.

M. plebeia occurs abundantly in the Middle Devonian limestone of Mount Wise and
Stonehouse Hill, near Plymouth ; at Barton and Lummaton, near 'l'orquay; Ramsleugh
Quarry, near Ogwell ; Woolborough, near Newton Abbot; and at Hagginton Hill, near

Ilfracombe, in Devonshire. On the Continent it occurs at Gerolstein, in the Eifel; at
Elbersreuth, &c.

RETZIA. 21

Genus—Retzia, King.

Rerata verira, Von Buch (sp.), 1834. Pl. IV, figs. 8—10.

TEREBRATULA FERITA, Von Buch. Ueber Terebrateln, 1834, p. 76, pl. ii, fig. 37; Mém.
~ Soe. Géol. de France, vol. iii, pl. xvii, fig. 4.
— — Phillips. Pal. Foss. of Devon, Cornwall, and West Somerset, p. 89,
pl. xxxv, fig. 163, 1841.
—_ — D Archiac et De Vernewil. Trans. Geol. Soc., 2nd ser., vol. vi,
p- 368, pl. xxxv, fig. 3, 1841.
SEIRIGERINA FeRITA, D’Orb. Prodrome, vol. i, p. 100, 1849.
TEREBRATULA — Quenstedt. (landb. der Petrefactenkunde, p. 475, pl. xxxviii, figs. 13,
14, 1851.
— — Schnur, in Dank. u. Von Meyer’s Paleontograph., vol. iii, p. 184,
pl. xxv, fig. 4, 1853.
Rerzia rerira, Sandberger. Die Brachiopoden des Rheinischen Schichtensystems in
Nassau, p. 34, pl. xxxil, fig. 13, 1855.

Spec. Char. Shell somewhat sub-triangular or oval, longer than wide, the greatest
width being situated about the middle of the shell, or towards the front. Valves mode-
rately convex. Surface costated; in the dorsal valve there exist five, seven, or nine strong
ribs, of which the central one is usually (although not always) the largest, while in the
ventral valve there are four, six, or eight, with a deep median groove corresponding to the
central rib of the opposite valve. ‘The surface of ‘the valves is likewise crossed by
numerous fine contiguous concentric striz, while the shell-structure is very finely punctured.
Beak elongated, nearly straight, tapering, and truncated by a small circular foramen which
is rendered complete, and is separated from the hinge-line by a long narrow deltidium, a
flattened space or small triangular area existing between the beak-ridges and the short
nearly straight hinge-line.

In the interior, the shelly spiral processes are directed outwards. Proportions
variable in different specimens.

Length 6, breadth 5, depth 3 lines.

Obs. his elegant little species has been several times beautifully figured, and is
characteristic of the Middle Devonian limestone of England, as well as of the Continent. It
occurs at Barton and Lummaton, near Torquay; near Newton Abbot, and at Dock
Yard, near Plymouth. On the Continent it has been found in the Eifel at Villmar, in
Nassau, &c.

22 BRITISH’ DEVONIAN BRACHIOPODA.

Genus—Uncites, Defrance.

Uncites erypnus, Schlotheim (sp.). PITY, Hes. 11, Az.

TEREBRATULA, Beuth. Julize et Montium Subterranea, &c., p. 134, No. 74, 1776.
TEREBRATULITES GRYPHUS, Schlotheim. Petrefactenkunde, pl. xix, fig. 1, 1822.
Uncites GrypHoipes, Defr. 1. Fér. Bull., 1827, xii, 152.
UNcITEs GRYPHOIDES, Blainville. Conchyliologie et Malacologie.
— GrypuHus, Bronn. Lethza Geogn., 1 Auf, pl. ii, fig. 6.
Gyprpia GRyYPHOIDES, Goldfuss. Von Dechen’s Translation of Sir H. De La Beche’s Manual,
p. 527, 1832.
TEREBRATULA GRYPHUS, VY. Buch. Ueber Terebrateln, p. 69, 1834, and Mém. Soe. Géol.
France, vol. iii, p. 174, pl. xvi, fig. 18, 1838.
UncITES GRYPHOIDES, Quenstedt. Handb. Petrefactenkunde, p. 459, pl. xxxvi, fig. 40,
1851.
— Grypuus, Davidson. British Fossil Brachiopoda, Introduction, vol. i, p. 89, pl. vil,
figs. 79—86, 1853.
—_ — Sandberger. Die Brachiopoden Rheinischen Schichtensystems in Nassau,
p. 38, pl. xxxi, fig. 5, 1855.
—_ — Woodward. A Manual of the Mollusca, p. 225.

Spec. Char. Shell elongated, oval ; bi-convex valves nearly equally deep, with a long
incurved beak, tapering at its extremity, hollow and truncated in young specimens by a
small, oval, apical foramen; no true area, a large concave deltidium partly surrounds the
aperture, and extends to near the cardinal edge. ‘The umbo of the dorsal valve is con-
siderably incurved, and partially concealed by the deltidium of the opposite valve. The
sides of the beak as well as the lateral portions of the umbo become at times considerably
deflected inwards, producing deep, lateral, elongated, concave depressions or pouches
opening externally, but not communicating with the interior. Surface covered with
numerous longitudinal radiating striz, or flattened ribs, which bifurcate at variable dis-
tances from the beak and umbo. Valves articulating by the means of teeth and sockets.
Shell impunctate. Dimensions variable.

Length 16, width 14, depth 9 lines,

Obs. The interior characters of this species have not been completely determined.
Professor Beyrich discovered in one specimen internal spiral processes, directed outwards ;
but I have some misgivings as to these spirals having in reality belonged to the specimens
in question, and should be glad to find Professor Beyrich’s discovery confirmed by the
evidence of other specimens. The shape and position of the muscular impressions
remain likewise still unknown; and it must also be remarked that the singular lateral
pouch-shaped depressions do not occur in all the specimens. The beak is rarely straight,
being more often bent to one side or the other.

ryyy,: . . . . »
This remarkable shell has been long known as characteristic of a certain horizon of

SPIRIFERA. 23

the Devonian period (‘ Stringocephalen-Kalk’ of the Germans), but had not been noticed
as a British fossil until the month of April, 1863; when I had the good fortune to discover
one or two small incomplete examples among some fossils sent me by Mr. Champernowne,
which he had obtained from a quarry on his estate of Dartington, near Totness, in
Devonshire. The upper beds of the Dartington band of limestone contain the Uneites ;
and it is found likewise a little lower down in a dolomite, which is partly decomposed,
forming quite sandy masses. Along with the shell under description I recognize the
following species ;—Apirifera nuda, Sp. octoplicata, Atrypa recticularis and A. aspera, Pen-
tamerus brevirostris, Rhynchonella primipilaris, and R. impleaxa, and one or two others not
sufficiently perfect to warrant a correct specific determination being arrived at. A larger
and perfectly characterized species of the shell under description has also been discovered
by Mr. Vicary, in Lane’s or Woolborough Quarry near Newton Abbot. ‘The British
examples of Uncites hitherto discovered are small, however, when compared with others
which I have picked up in the neighbourhood of Paffrath, and at Klustein near Gladback,
in the vicinity of Cologne, and which attained nearly two and a half inches in length.
Von Buch states that it is small at Gerolstein; and I have it also from Nimes in Belgium.
Dr. F. Sandberger gives an excellent figure of a specimen he found in the Devonian lime-
stone of Nassau.

Genus—SPiriFERA, Sowerby.

SpIRIFERA DIssuNcTA, Sow. PI. V, figs. 1—12; Pl. VI, figs. 1—5.

SPIRIFERA DIsJUNCTA, Sow. Trans. Geol. Soc., 2nd ser., vol. v, pl. liii, fig. 8; pl. liv, figs.
12, 13.
— cALcaRATA, Sow. Ibid., pl. liii, fig. 7.
—_ EXTENSA, Sow. Ibid., pl. liv, fig. 11.
— GIGANTEA, Sow. Ibid., pl. lv, figs. 1—4,
— tnornata, Sow. Ibid., pl. liii, fig. 9.
— _ pROTENSA, Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 69,
pl. xxviii, fig. 119, 1841.
— catcarata et Sp. pissuncra, Phillips. Ibid., pl. xxix, figs. 128, 129.
— pissunota, Phillips. Ibid., pl. xxx, fig. 129.
— GiGanTea, Phillips. Ibid., pl. xxx, fig. 130.
? — GRand&va, Phillips. Ibid., pl. xxx, fig, 131.
— _ pistans, Phillips (not Sow.). Ibid., pl. xxix, fig, 127.
— VeERNEUILU, Murch. Bull. Soc. Géol. France, vol. xi, p. 252, pl. ii, fig. 3,
1840.
— Arcuiact, Murch. Ibid., pl. ii, fig. 4.
— Lonspaet, Murch. Ibid., fig. 2.
Sprrirer DisJuNcTUS, De Verneuil. Geol. of Russia, vol. ii, p. 157, pl. iv, fig. 4, 1845.

24 BRITISH DEVONIAN BRACHIOPODA.

Sprrirer Arcuract, De Verneuil. Geol. of Russia, vol. ii, p. 157, pl. iv, fig. 6, 1845.
= Morcuisontanus, De Kon. De Vern. and Keys., Geol, Russia, vol. 11, pl. iv, fig. 1,

1845.
— DisJuNoTUS, Dav. Quarterly Journal of Geol. Soc., vol. ix, p. 354, pl. xv, figs.
1—5, 1853.

— VerRNEvVILI, M‘Coy. British Pal. Fossils, p. 376, 1852.
— _ pissJunotus, Murchison. Siluria, 2nd edition, p. 299, fig. 4, 1859.
— Barumensts, Sow. MS,. Salter, Journal Geol. Soc., vol. xix, p. 480.

Spec. Char. Shell variable in shape, transversely semicircular or subrhomboidal ;
hinge-line usually as long as the width of the shell, with the cardinal angles slightly
rounded, or extended to a greater or smaller extent, in the shape of long, attenuated,
contracted prolongations ; valves convex, sometimes gibbous. In the dorsal valve the
mesial fold is sharply defined, of moderate convexity and elevation ; m the ventral valve
the sinus is concave; beak produced and moderately incurved ; area triangular, flat, or
concave, and of greater or smaller dimensions; fissure partly arched over by a pseudo-
deltidium in two pieces. The surface of each valve is ornamented by from forty to ninety
small radiating ribs, with interspaces of almost equal width. The ribs are simple on the
lateral portions of the shell, but increased in number to a small extent on the mesial fold
and sinus, by means of intercalated ribs, which appear at variable distances from the beaks;
the whole surface is crossed by numerous, fine, contiguous, concentric lines. Dimensions
variable, some very large examples having attamed as much as two or more inches in
length, by three or three and a half inches in width; but the larger number possessed
smaller proportions.

Oés. 'Yhis very important Middle and Upper Devonian species has been described and
illustrated under many denominations ; but I quite concur with those paleontologists who
have considered Sp. calcarata, Sp. eatensa, Sp. gigantea, Sp. inoraata, Sp. Verneuilit, Sp.
Lonsdalei, Sp. Archiaci, and Sp. Murchisoniana, and one or two more, as mere synonyms or
variations in shape of a single species. Sp. profensa was founded on a single decorticated
and injured specimen of what I take to be a mere variation in shape of the shell under
description. Sp. grandeva has been described from such very imperfect material that it is
hardly safe to offer any opinion as to its specific value, further than to say that Phillips’
figure looks very like a variation in shape of Sp. disjuncta, and that the author
himself admits that it is “decidedly alhed to Sp. gigantea, but with only half the
number of lateral ribs.” It must be borne in mind that Sp. grandeva is a small
shell, while Sp. gigantea is a very large or fully grown condition of the species, and is
consequently possessed of a larger number of ribs. The term Sp. Barumensis appears to
be a local name given to a large variety of Sp. disjuncta, with an unusually developed area ;
but the area is also very large in some examples of Sp. disjuncta proper, and cannot, there-
fore, be made use of as a specific character. I quite coincide with the observations made
by Professor M‘Coy, that, ‘“‘when the shell approaches its adult size, it becomes the

SPIRIFERA. 25

Sp. gigantea of Sowerby and Phillips, without the slightest change of character, so that
many of the specimens at Petherwin and Tintagel could not be referred by a conscientious
observer to the one species in preference to the other. The character supposed by Phillips
to distinguish Sp. gigantea from Sp. disjuncta, viz., the mesial fold being ‘indistinctly
furrowed or nearly smooth,’ is negatived by Mr. Sowerby’s original figures, by his type-
specimens, and the greater number of others which I have seen. Mr. Sowerby has himself
suggested the possible identity of his Sp. disjuncta and Sp. gigantea ; and De Koninck and
De Verneuil suspected the possible union of the four so-called species here united. Cleavage
and pressure have produced the most singular contortions in specimens of this and other
species ; some are completely flattened or greatly elongated, while others are made to
assume much more than their natural width ; some, again, are bent and twisted to the one
or other side, and completely put out of shape.’

When describing Sp. calcarata, Sowerby states that his shell (of which the charac-
ters are taken from a single internal cast) “approaches closely to Sp. attenuata, M.C. ;
but distinguished by the sudden contraction of the sides and the very slight elevation of
the front. Still we have some doubts of its being distinct from the many varieties of that
species.” ‘This leads me to observe that I possess two or three specimens of Sp. sériata,
var. attenuata, with simple lateral ribs, identically similar in every respect to the Devonian
example (Pl. V, fig. 4); but it must be remembered that in the greater number of specimens
of Sp. striata the ribs upon the lateral portions of the valve augment very much in number
by the intercalation of additional ribs at various distances from the beak and umbone,
while in Sp. disjuncta they are all simple. It is, therefore, easy by this character alone to
distinguish the larger number of specimens of the two species, while we cannot deny that
some few can hardly be separated. The character of the ribs in the fold and sinus of the
Carboniferous and Devonian species are exactly similar; and in both we often find a couple
of deeper grooves, which sometimes appear to divide the fold into three portions, as is so
common in Sp. disulcata. Sp. disjuncta occurs in the Upper Devonian brown grits of
Croyde Bay, seven miles west-north-west of Barum; in the neighbourhood of Barnstaple,
Braunton, &c.; at South Petherwin, in slates and subordinate limestone; in chloritic

1 The reader is referred to a very interesting and important paper ‘On Slaty Cleavage,”’ by Daniel
Sharpe, in the ‘ Quarterly Journal of the Geological Society,’ vol. v, p. 74, 1847, in which the author has
given an elaborate description and illustration of the many modifications effected on Spirifera disjuncta
by cleavage. He also observes, that “in determining the species of fossils of the older forma-
tions, great difficulties arise from the distortion of form which they have frequently undergone, which
sometimes makes it impossible to ascertain the species or even the genus to which they belong. This
distortion varies much in specimens from the same locality, and still more so in those from different
districts. . . . . . These differences in the angle at which the cleavage intersects the bedding
appear to have had an influence on the amount of distortion of the organic remains, as these are usually
most altered in form where the angle of incidence of the planes is the least. . . . . . The distortion
of the organic remains, in each bed, is in proportion to its cleavage; in the slates they are extravagantly
distorted, in the limestones slightly so, while in the soft ochreous beds, in which there is little cleavage,
the fossils have preserved their form nearly unaltered. . . . . .” &e.

D

26 BRITISH DEVONIAN BRACHIOPODA.

slate at Tintagel, &c.; in the Middle Devonian limestone, at Woolborough, near Newton
Abbot; at Ilfracombe, Barton, Lummaton, and Hope’s Nose, near Torquay, &c. Also
in slaty and sandy beds between thick Carboniferous Limestone and genuine Old Red
Sandstone in various localities in the County of Cork, Ireland. On the Continent it
abounds at Ferques, in the Boulonnais, &c., in France ; at Chimay, &c., Belgium ;
Ferrones, Spain ; in Nassau, Stolberg, near Aix-la-Chapelle ; in Russia, America, China, &c.

? SPIRIFERA CANALIFERA, Val. (sp.) in Lam., 1819. Pl. VI, fig. 9.

TEREBRATULA CANALIFERA, Val.in Lam. Hist. Nat. des Animaux sans Vertébres, vol. vi,
p- 254, 1819. Encycl. Méthodique, pl. cexliv, fig. 5; and
Dav., Notes on an Examination of Lamarck’s Species of
Fossil Terebratulee, Annals and Mag. of Nat. Hist., 2nd series,
vol. v, p. 442, pl. xiv, fig. 40, 1850.

TEREBRATULITES APERTURATUS, Sch/oth. Nachtragen zur Petrefactenkunde, pl. xvii, fig. 1,

1822.
SPIRIFERA APERTURATA, Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset,
p. 77, pl. xxx, fig. 133, 1841.

Spec. Char. Shell somewhat transversely sub-rhomboidal, rather wider than long ;
hinge-line shorter than the width of the shell; cardinal extremities angular. Valves
convex, sometimes gibbous. Dorsal valve semicircular; mesial fold sharply defined, of
moderate elevation, and flattened along its middle ; the surface of the valve is ornamented
by a variable number of simple or bifurcating ribs, these being smaller on the fold than
on the lateral portions of the valve. Ventral valve deeper or more convex than the
opposite one, with a wide, shallow sinus, this valve and its sinus being ornamented
similarly to the dorsal one. Beak more or less incurved, area triangular, and of variable
breadth. Fissure partly arched over by a aoa deltidium. Proportions variable.
Length 22, width 23, depth 20 lines.

Obs. At p.77 of his work on the ‘ Paleozoic Fossils of Cornwall, Devon, and West
Somerset,’ Professor Phillips mentions that only one specimen had occurred to his obser-
vation, from the coarse slaty rocks of Linton, in Devonshire, and that it may be viewed as
identical with the fossil of Bronn and Schlotheim, though there is a rather nearer approach
to equality between the mesial and lateral ribs. Not having been able to procure a sight
of the fragment described by Phillips, or of any other British specimen, I must quote this
species as a British fossil entirely upon the authority of Professor Phillips. Sp. canalifera
has much of the general shape of Sp. disjuncta, but will be easily distinguished on account
of the bifurcation of its lateral ribs, a feature not observable in Sp. disjwncta. When ex-
amining Lamarck’s original types of fossil Terebratule, which had been kindly lent me
by the Admiistration of the Jardin des Plantes, I had occasion to notice that the
Terebratula canalifera of Val. in Lam. belonged to the genus Spirifera, and that reference

SPIRIFERA. 27

is made by that author to pl. 244, fig. 5, of the ‘ Encyclopédie Méthodique,’ for a figure
of the type of his species, and which belongs to the well-known Devonian shell subse-
quently described and figured by Schlotheim in 1822, under the name of Zerebratulites
aperturatus, and I am glad to find that Valenciennes’ or Lamarck’s name is now made
use of by the generality of paleontologists. It is at the same time necessary to mention
that Valenciennes’ var. (pl. 244, fig. 4, of the ‘Encyc. Méth.’) is a specimen of Sp. dis-
juncta, Sow., and not of canalifera.

Sp. canalifera occurs in the Devonian limestone of Paffrath, near Cologne, in Prussia.

Not having been able to procure the sight of a specimen of the following four so-
termed species, and as the illustrations given by Phillips are extremely incomplete, I will
reproduce the original descriptions and figures simply as memoranda, not wishing to
take any responsibility as to their specific value. It is also uncertain whether the rocks
containing the first three are Devonian, or whether they should not be classed as Carbo-
niferous.

?? SprrireRA MESOMALA, Philips. PI. VI, fig 8.

SPIRIFERA MESOMALA, Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 78,
pl. xxxi, fig. 137, 1841.

“ Characters. Depressed, transversely elongated, radiated from the beak, with many
small lateral and a few broad, flat, mesial undulations. It is this latter circumstance
which attracted my attention. ‘The mesial ridge of the upper valve of ordinary Spirifera
is here a broad, flat, acute-edged fold, margined by two broad grooves, beyond which
small radiating ribs cover the sides. Locality. In North Devon, Brushford.”

PP SprrireRA OBLITERATA, Phillips. Pl. VI, fig. 10.

SPIRIFERA OBLITERATA, Phillips. Pal. Foss. of Cornwall, Devon, &c., p. 78, pl. xxxi, fig.
135, 1841.

“Semicircular, more than twice as wide as long, very convex, with extended acute
terminations to the cardinal area; surface radiated with rounded, very little prominent
undulations, crossed by distant lines of growth. Mesial sulcus slight, placed between
two obtusely convex radiations much larger than the rest. Allied to Sp. speciosa, and
the species ranked with Sp. rhomboidea, Sp fusiformis, &c.,in the Mountain-limestone.
Locality. In North Devon, Brushford.”

28 BRITISH DEVONIAN BRACHIOPODA.

? ? Sprrirera MEGALOBA, Phillips. PI. IX, fig. 23.

SPIRIFERA MEGALOBA, Phill. Pal. Foss., pl. xxx, fig, 140, 1841.

“ Characters. General figure rhomboidal (?), gibbous ; surface radiated with very
few, extremely broad, transversely imbricated ridges and hollows. Having seen only the
crushed specimens here represented, Iam not able to present a more perfect description,
but I presume it will be easily recognized. Locality. North Devon, Brushford.”

PP Sprrirera RupIs, Phillips. Pl. IX, figs. 24 and 25.

SPIRIFERA RUDIS, Phill. Pal. Foss., p. 78, pl. xxxi, fig. 136, 1841.

“The specimens figured are all that have fallen under my notice, and not sufficient
to allow of precise definition. I found them in a hard black limestone, among the slaty
rocks of Croyde Bay, on the south side of Baggy Point. Locality. Baggy Point, North
Devon.”

SprRIFERA L&vicosta, Val. (sp.) in Lamarck. Pl. VIII, figs. 4, 5.

TEREBRATULA LEVIS E MaJorIBUS, &c., Beuth. Julie et Montium Subterranea, p. 146,
No. 158, 1776.

— L&vicosta, Val. in Lamarck. Hist. Naturelle des Animaux sans Vertébres,
vol. iv, p. 254, 1819; and Davidson, ‘‘ Notes on an Exami-
nation of Lamarck’s Species of Fossil Terebratulz,” Annals
and Mag. of Nat. Hist., 2nd series, vol. v, p. 443, 1850.

TEREBRATULITES OSTIOLATUS, Schlotheim. Nachtragen zur Petrefactenkunde, pl. xvii, fig. 3,
1822.
SPIRIFER — Von Buch. Ueber Delthyris oder Spirifer und Orthis, p. 33,
1837; and Mémoires Soc. Géol. France, vol. iv, p. 178, pl. viii,
fig. 1, 1840.
= — Steining. Eifel, p. 33.
— — Bronn. Index Paleontologicus, p. 1178, 1848.
~— — Quenstedt. Handi. der Petrefactenkunde, p. 477, pl. xxxviii,
fig. 17, 1851.
oom — Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset,
p. 76, pl. xxx, fig. 132, 1841.
L&vicosta, M‘Coy. British Pal. Fossils, p. 375, 1852.
— — Schnur, in Dunker u. Von Meyer’s Paleeontographica, vol. iii,
pl. xxxii’, fig. 3, 1853.

Spec. Char. Shell rotundato-quadrate, slightly wider than long ; valves very convex ;
hinge-line hardly as wide as the shell; ventral area concave, of moderate width; beak

SPIRIFERA. 29

slightly incurved, with a smooth mesial smus extending from the extremity of the beak to
the front, and to which in the dorsal valve corresponds a rather wide, smooth, prominent,
mesial fold. Hach valve is ornamented by from twenty to thirty simple, obtusely rounded
ribs. ;

Length 15, width 15, depth 13 lines.

Oés. No reference as to figure is given by Lamarck ; but it is stated that the fossil
was found at Bensberg, near Cologne. M. Valenciennes informed me, when sending his
type for my inspection, and which is preserved in the Muséum du Jardin des Plantes in
Paris, that he had received the shell from which he established the species in 1817 from
Professor Néggerath, while on a visit to Bonn; and it was figured by myself in the ‘ Annals
of Nat. Hist.’ for 1850. A similar specimen was illustrated and described in 1822 by
Schlotheim, under the designation of Terebratulites ostiolatus, and subsequently placed
among the Spirifers by Von Buch, and by Bronn in Kénig’s genus Zrigonotreta. But
since Valenciennes appears to have been the original describer of the species, it should
retain the name of /evicosta, and I am glad to find that Professors Schnur, M‘Coy,
Morris, and several other paleeontologists, have adopted this view. ‘To Professor Quenstedt
we are indebted for an excellent figure, showing the shape and position of the spiral
appendages.

Sp. levicosta does not appear to be a very common fossil in Great Britain. It occurs
in the Devonian shales of the Valley of the Rocks, Linton, North Devon. Phillips’s figured
specimen, which is a mere incomplete impression of the ventral valve, is preserved in the
Museum of the Geological Survey. It has also been found in Middle Devonian limestone
near Newton Abbot. On the Continent it is common in the Eifel, at Chimay, &c.

SpiriFeRA spEcIosa, Schlotheim (sp.). Pl. VIII, figs. 6—8.

TEREBRATULITES sPEcTosus, Schlotheim. Taschenbuch fiir die gesammte Mineralogie, pl. ii,

fig. 9, 1813.
—_ PARADOXUS, Id. Ib., pl. ui, fig. 6.
— SPECIOSUS, Id. Nachtragen zur Petrefactenkunde, pl. xvi, fig.1,
1822.
-— INTERMEDIUS, Id. Ib., fig. 2.

TRIGONOTRETA SPECIOSA, Koenig. Icon. Foss. Sectiles, iii, pl. vi, fig. 71.
— _ Bronn. LUethea Geog., pl. ii, fig. 15.
DELTHYRIS MICROPTERA, Goldf., in Von Dechen’s Translation of Sir H. De La Beche’s
Manual, p. 525, 1833.

SprriFeR spectosus, Von Buch. Ueber Delthyris oder Spirifer und Orthis, p. 35, 1837;
and Mém. Soc. Géol. de France, vol. iv, p. 180, pl. viii, fig. 4,
1840.

== — Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 77,

pl. lviii, fig. 134, 1841.

30 BRITISH DEVONIAN BRACHIOPODA.

? SPIRIFER CostTaTus, Sow. Trans. Geol. Soc., 2nd series, vol. v, pl. lv, figs. 5, 6.

— speciosus, D’ Archiac et De Verneuil. Descriptions of the Fossils in the Older
Deposits of the Rhenish Provinces, Trans. Geol. Soc., 2nd series,
vol. vi, pp. 395 and 408, pl. xxxviii, fig. 5.

— _ SPECIOSUS = INTERMEDIUS und PARADOXUS, Bronn. Index Palzontologicus,

p. 1181, 1848.
— — M‘Coy. British Pal. Foss., p. 376, 1852.
— — Schnur, in Dunker u. Von Meyer’s Paleontographica, vol. iii, pl. xxxii,
fig. 2, 1853.

Spec. Char. Shell transversely fusiform; hinge-line straight and long; cardinal angles
and lateral margins gradually attenuated ; valves moderately convex ; beak small, incurved ;
ventral area of moderate breadth; sinus wide, regularly concave, extending from the ex-
tremity of the beak to the front, and to which corresponds a mesial fold in the opposite
valve. ach valve is ornamented by from twelve to eighteen, or more, simple rounded
ribs, the surface of the shell being regularly and closely crossed by sharp, concentric lines
or laminee of growth.

Length 9, width 18 lines ; but the shell has attained larger proportions.

Ods. Characteristic specimens of this species occur in the Middle Devonian shales of
Hope’s Nose and Meadfoot, near Torquay. Professor M‘Coy mentions its occurrence at
Fowey, East Looe, St. Veep, Polruan, &c., in Cornwall; but from these localities no
specimens have come under my notice. On the Continent it is common in the Eifel, at
Convin in Belgium, and Luga; also in the States of Ohio and New York in America.

This appears to be a very variable shell, and has been somewhat differently interpreted
by paleontologists. It may therefore be desirable to enter upon some details in connection
with its history.

The first notice we can find of Spzrifera speciosa is contained in p. 52 of Leonhard’s
‘Taschenbuch,’ for 1813. The shell is not described, but mentioned by Schlotheim in the fol-
lowing words:—*‘Zerebratulites speciosus,aus der Gegend von Belinzona: meine Sammlung;”
and in the accompanying pl. ii, fig. 9, he gives a representation of his species. The shell is
fusiform, with a simple fold and sinus, each valve being ornamented by some ten or twelve ribs,
the whole closely traversed by concentric lines or slightly projecting laminee. Subsequently,
in 1822, and at p. 252 of his ‘Die Petrefactenkunde,’ Schlotheim again mentions his species,
and gives a good illustration of it in pl. xvi, fig. 1, of his work. This specimen shows
about twenty-eight rounded ribs in each valve. Here, also, for the first time, he intro-
duces his so-termed Zerebratulites intermedius (pl. xvi, fig. 3), which the generality of
palzeontologists consider to be a simple variety or variation in shape of Sp. speciosa, with
about twelve ribs upon each of its valves. Both are stated to have been derived from the
Eifel.

In 1833 Goldfuss appended a list of fossils to Von Dechen’s translation of Sir H.
De La Beche’s ‘ Manual of Geology,’ and introduced a number of new names without
description or illustration, and has thus furnished us with another instance of the confusion

SPIRIFERA. 31

that can be created by the pernicious effect of manuscript names. Here we find for the
first time, at p. 525—\“ Delthyris micropterus, Goldf., 7. intermedius, Schloth.—Eifel,
Gloucestershire, Herefordshire, &c ;” but no such species occurs in the counties named.

Now, I cannot understand why he should have introduced this new name, since he
considers it and Schlotheim’s 7- intermedius to be synonymous! Here we find also—

“ Delthyris macropterus, Goldfuss,—= 7. speciosus and T. paradowus, Schl., of the Eifel.”

Therefore, according to Goldfuss, Sp. speciosus and Sp. paradozxus, and Sp. macropterus,
would be synonymous, and in default of description we are bound to take him at his word.

In 1837, at p. 35, of his ‘ Ueber Delthyris,’ &c., Von Buch enlarges upon the subject
of Spirifer speciosus, and adds—‘ Among the principal varieties of this species we may
reckon the following—

“1. Sp. speciosus micropterus, Goldt., with from ten to eighteen ribs on each side of the
fold.” But the celebrated Prussian paleontologist is, I] think, mistaken when stating
that Sp. distans, Sow., may belong to this variety.

2. Sp. speciosus intermedius, Schloth. (macropterus, Goldf.). Six to eight large ribs on
each of the lateral portions of the valve, or from twelve to sixteen ribs, without counting
the fold.”

I must here express my surprise that, after Goldfuss has so distinctly intimated that
his Delthyris micropterus = T. intermedius, Schloth., and that his Delthyris micropterus =
T. speciosus and T. paradoxus, another interpretation should have been put upon the
matter by Von Buch.

“3. Spirifer speciosus alatus.” This last is a Permian shell, which appears to be
closely related to Sp. macropterus.

I consider Von Buch likewise mistaken when he states that Sp. convolutus, Phillips,
Sp. fusiformis, Sow., and Sp. rhomboidalis, Phillips, may be varieties of Sp. speciosus, the
character of the mesial fold and sinus being sufficient to negative such a conclusion.

At p. 1181 of his ‘Index Palzontologicus’ (1848), Dr. Bronn gives us a long list of
synonyms and references to Schlotheim’s Sp. speciosus ; and among them we find Delthyris
microptera, Goldfuss, Hysterolithes hystericus, Schloth.; and as named varieties, B. Zere-
bratulites intermedius, Schloth., and y. Terebratulites paradoxus of the same author. But
I must confess that the figures given by Schlotheim of his Hysterolites hystericus lead me
to believe that it cannot be considered as a synonym of Sp. speciosus.

In vol. v of the ‘ Transactions of the Geological Society of London,’ 2nd series (May,
1840), Sowerby describes and figures some very imperfect and distorted casts and impressions
of a fusiform Spirifera, not unlike Sp. speciosus or Sp. paradoxus, under the denomi-
nation of Sp. costata, and adds, “(—‘S. speciosa of the Eifel ?),” implying that it might be
synonymous with Schlotheim’s species ; and in 1852 Professor M‘Coy (‘ British Pal. Fossils,’
p- 376) unhesitatingly places Sp. costata as a synonym of Sp. speciosa. Phillips, i his
‘Figures and Desc. of the Pal. Fossils of Cornwall, Devon, &c.,’ p. 77, 1841, adopts
Sowerby’s Sp. costata, but observes, at the same time, that it “certainly resembles “yp

32 BRITISH DEVONIAN BRACHIOPODA.

spectosus of Bronn, ‘ Leth. Geog.,’ pl. u, fig. 15 (which is not quite like Zered. speciosus,
Schloth., pl. xvi, fig. 1); but that its lateral ribs are much more decided even in a cast
—it appears distinct. It seems also nearly allied to Sp. undulata, Sow., from the
magnesian limestone of East Trichley.” But I would here again observe that all
Phillips’s and Sowerby’s figures of Sp. costata, which represent very badly preserved and
distorted casts, have not angular, but rounded ribs, just as in Sp. wadulata and Sp.
speciosa proper. We would not, therefore, venture to admit Sp. costata as a distinct
species upon such unsatisfactory material.

We now come to the ‘ Tables of the Distribution of the Fossils in the Older Deposits
of the Rhenish Provinces,’ by Viscount D’Archiac and M. De Verneuil, p. 395, 1840,
where we find Hysterolites paradoxus, and H. vulvarius, Schlotheim, given as synonyms
of Sp. speciosus ; and this leads me to fear that our distinguished friends may have intended
to allude only to the Zerebratulites paradoxus of Schloth., Hysterolithes vulvarius of that
author belonging to the genus Orthis.

Further on, at p. 408 of the same memoir, in an appendix by J. De Carle Sowerby,
we find—“ Pl. xxxvii, fig. 5, Sp. speciosus, Schloth. . . . Sp. macropterus, var.,
Goldfuss, MS.?: there is no character that I am aware of to distinguish this form
from Sp. speciosus of Schlotheim ; but, as the internal structure exhibited by the cast is
totally different from that of Sy. micropterus (?), I quote Goldfuss with doubt.”

Sowerby further on considers the last-named shell, as a synonym of Hysterolites
hystericus, Schloth., to be specifically distinct ; a view also advocated by De Verneuil,
at p. 394 of his ‘Tables :’ and here commences another phasis in the confusion involving
these several Devonian so-termed species.

In 1851 Professor Schnur considered Sp. micropterus, Goldf., to be a variety of Sp.
ostiolatus ; and later, in his work on the Eifel Brachiopoda, ‘ Paleeontographica,’ vol. iii, p-
197, places Sp. entermedius, Schloth., among the varieties of Sp. speciosus ; considers Sp.
paradoxus, Schlotheim, to be a distinct species ; Delthyris macropterus, Goldf., bemg men-
tioned as a synonym; and proposes a third species by the name of Sp. subcuspidatus,
with which he locates Delthyris micropterus, Goldf., and Hysterolites hystericus, Schloth.,
as synonyms.

And lastly, in his ‘ Die Brachiopoden des Rheinischen Schichtensystems in Nassau,’ p.
21 (1855), Dr. Sandberger admits as a species Sp. macropterus, Goldfuss, and considers
Sp. mucronatus and Sp. micropterus, Goldfuss, as varieties of the same.

From all this diversity of views it is difficult to arrive at any positive opinion with
reference to the synonyms of Sp. speczosa; but I am inclined to believe that Sp. intermedia,
Sp. paradoxa, Schloth., Sp. costata, Sow., Sp. macroptera, and Sp. microptera, Goldfuss,
may all be varieties or modifications im shape of a single very variable species. My
material in German specimens of the shells here named is not, however, as extensive
as I could have desired, and therefore trust that the subject will be reconsidered by some
of the German paleontologists.

SPIRIFERA. 33

Schlotheim’s first notice of Sp. paradovus will be found in the ‘ Taschenbuch fiir die
gesammte Mineralogie’ for 1813, pl. ii, fig. 6. This figure represents the internal cast
of a very fusiform Spirifer, with a smooth sinus, and about thirty-eight rounded ribs, and
not very unlike specimens 1] and 13 of our Pl. VIII.

We will therefore provisionally refer our figs. 6, 7, 8, to Sp. speciosa proper, and
figs. 9, 10, 11, and 13 to the var. paradowa of Schlotheim.

The imperfect specimen, fig. 12, from the Middle Devonian shales of West Ogwell,
I am unable to identify with any degree of certainty. It has been referred by the Survey
paleontologists to Sp. Bouchardit, and we find it so registered at p. 151 of the second
edition of Professor Morris’s ‘Catalogue of British Fossils.’ The wide triangular area
exhibited by this specimen leads M. Bouchard and myself to question the identification,
the area of Sp. Bouchardit being in all the very many specimens hitherto found, linear,
narrow, and parallel, and we can perceive no median rib in the sinus of the ventral valve
of our English specimen, although this rib, which exists in well-shaped specimens of Sp.
Bouchardii, is at times absent or obscurely defined. In external shape and angularity of
its ribs, the shell under notice resembles some American examples of Conrad’s Delthyris
mucronata ; but here again we have a linear, parallel area, and not a triangular one, as
seen in the Ogwell specimen.

M. Bouchard objects to the assimilation made by Herr F. Roemer, and some other
paleontologists, of Sp. Bouchardii with Sp. comprimatus, Schlotheim (‘ Min. Taschenbuch,’
tab. ii, fig. 8); but, not having seen the original specimen, I dare not venture to express a
positive opinion upon the question, and especially as Schlotheim’s figure differs much
in general shape from the shell to which De Verneuil has applied the designation of
Bouchardii. M. Bouchard informs me that he has never seen any true example of Sp.
Bouchardii from the Eifel, and that he is convinced that the specimen of Sp. Bouchardii
figured by F. Roemer, under the denomination of Sp. comprimatus, Schloth. (‘ Rheinisch.
Uebergangsgeb.,’ pl. iv, fig. 3, 1844), was obtained at Labuyssiére-sur-Sambre, in Belgium;
and I may add that I possess specimens from that locality identical in shape and character
with Roemer’s figures. Up to the present time I have not seen any true British example
of Sp. Bouchardit.

SPIRIFERA SUB-cusPIDATA, Schnur. Pl. VIII, figs. 14, 15.

SPIRIFER suB-cUsPIDATUS, Schnur. Programm, &c., die Brachiopoden aus dem Uebergangs-
gebirge der Eifel, p. t1, 1831.
= — Id. Dunker’s Paleontographica, vol. iii, p. 202, pl. xxxiv,
fig. 1, and pl. xxxiii, fig. 3, 1853.

Spec. Char. . Shell transversely semicircular, or obscurely sub-pentagonal ; hinge-line
as long as the width of the shell ; cardinal angles acute, sometimes prolonged, with tapering
E

34 BRITISH DEVONIAN RRACHIOPODA.

extremities; valves convex, with a smooth fold in the ventral valve. From twenty to
twenty-four angular ribs ornament the surface of each valve, the whole being traversed by
numerous concentric lines or slightly prominent lamine. Beak almost straight; area flat,
triangular, comparatively large; fissure partly arched over by a pseudo-deltidium. Two
specimens have measured—

Length 10, width 143, depth 6 lines.

ding Pts meal Be yt ais

Obs. Professor De Koninck and M. Bouchard are of opinion that the shell above
described should be referred to Sp. sub-cuspidatus, Schnur, and that it is specifically
distinct from the Hysteriolites hystericus of Schlotheim (?). Professor Schnur, however,
mentions as synonyms of his species Delthyris microptera, Goldfuss, and Hysterolites
hystericus of Schlotheim ; but, if this was his opinion, I cannot understand why he did not
adopt one of the two designations, instead of proposing a new name for the shell under
description.

Sp. sub-cuspidata occurs in the Middle Devonian limestone of Woolborough, near
Newton Abbot, and at Hope’s Nose, near Torquay. On the Continent it is a common
fossil in the Eifel. .

SPIRIFERA HYSTERICA, Schlotheim (?). (sp.) Pl. VIII, figs. 16, 17.

HyYsTEkIOLiTEs HysrEeRicus, Schlotheim. Erklarung der Abbildungen der zu diesem Werke
gehorigen Kupfertafeln, Petrefactenkunde, pl. xxix., fig. 1%,
1822.
Sprrirer MicroprEerus, D’ Archiac, De Verneuil, and J. De C. Sow. Descript. of the
Fossils of the Older Rhenish Provinces, Trans. of the Geol. —
Soc., 2nd series, vol. vi, pp. 394 and 408, pl. xxxviii, fig. 6:
(not of Goldfuss?).

Spec. Char. Shell transversely semicircular or sub-pentagonal ; hinge-line almost as
long as the width of the shell ; dorsal valve moderately convex ; fold simple, sharply defined,
rounded; ventral valve deeper than the opposite one, with a shallow sinus. Surface of
each valve ornamented by from twenty-six to thirty simple ribs ; beak slightly incurved ;
area triangular, of moderate width ; fissure partly covered over by a pseudo-deltidium.

Length 12, width 17 lines.

Oés. Impressions and internal casts of the shell under description do not appear
rare in the Middle Devonian (?) yellowish grits of Linton, in North Devon; but the
absence of the shell itself precludes the possibility of our arriving at a positive conclusion
as to its specific identification.

In external shape, character of fold, and number of ribs, it so nearly approaches
Schlotheim’s figures of #/. dystericus that I have ventured to provisionally leave it under
that designation. It also closely resembles the figures given by J. De C. Sowerby in

SPIRIFERA. 35

pl. xxxviii, fig. 6, of the ‘Geol. Transactions,’ above quoted; which figures resemble
likewise the original ones of hystericus published by Schlotheim. 1 cannot, however,
understand why Sowerby should have made use of the term Sp. micropterus, Goldfuss, for
his specimens, since he admits that they agree with /ysterolites hystericus, but which
last he stamps as a synonym of Sp. micropterus.

We may now inquire what is H. hystericus, Schlotheim ; and, in the absence of any
description or well-authenticated specimen, the question can be answered only by a close
examination of the author’s figures. These consist of internal casts of the dorsal and
ventral valves of a Spirifer imbedded ina slab of shale or grit, and which will answer to the
following description :

Shell transversely semicircular or sub-pentagonal; hinge-line about as long as the
width of the shell; valves convex, with a smooth mesial fold in the dorsal valve, to which
corresponds a similar sinus in the opposite one ; surface of each valve ornamented by some
twenty angular ribs, the widest of which does not much exceed one line in breadth ; length
14, width 20 lines; and this description would suit equally well to our Linton specimens.
It has been said that the surface of H. Aystericus was crossed by concentric lines or laminze
similar to those of Sp. speciosa and of other species; but these are not observable in
Schlotheim’s figures of internal casts any more than they could be seen on the Linton
specimens, and may have been present in both had we the shell itself to examine. ‘he
subject of this identification must remain an unsettled question until more perfect material
and direct comparisons can be effected between our Linton specimens and Schlotheim’s
original ones of /ystericus.

? SPIRIFERA cuLrRiguGATA, Roemer. Pl. VIII, figs. 1, 2, 3.

SPIRIFER CULTRIJUGATUS, Roemer. Rheinisch, Uebergangsgeb., p. 70, pl. iv, fig. 1, 1844.
— — Roemer. Beitrage zur geologischen Kenntness der nordwest-
‘ lichen Harzgebirges, in Dunker’s Paleontographica, pl. xv,
1852.
— — Schnur. Palzontographica, vol. iii, pl. xxxiii, fig. 1, 1853.
_ — Sandberger. Die Brachiopoden der Rheinischen Schichten-
systems in Nassau, pl. xxxii, fig. 4, 1855.

Spec. Char. Shell large, transversely semicircular ; hinge-line usually rather shorter
than the width of the shell ; dorsal valve convex, at times gibbous, with a large prominent
fold or central rib, and six or seven strong simple ribs on each of the lateral portions of
the valve; ventral valve convex, with a similar number of ribs and a wide median sinus ;
beak of moderate proportions, and incurved ; area triangular ; fissure large, partly arched
over by a pseudo-deltidium ; proportions variable, two British specimens have measured—

Length 1 inch 10 lines, breadth 23 inches.

s inches, S 3 inches 9 lines.

o>

36 BRITISH DEVONIAN BRACHIOPODA.

Obs. This large Spirifer occurs plentifully, but in a very distorted and compressed
condition, in the state of internal casts and impressions, in the Devonian grits of Looe,
in Cornwall.

With such imperfect material at our command, it is hardly possible to arrive at an
exact specific identification ; but the less injured specimens resemble, by their general aspect
and character of ribs and fold, some similar casts of Sp. cultrijugatus 1 have received
from the Hifel district, and which were sent to me so named by Herr F. Roemer. In all
the figures published by Roemer, Schnur, and Sandberger, of Sp. cultrijugatus, the ribs on
the lateral portions of the shell are simple, and do not exceed about twenty on each valve ;
but in a specimen so named in my possession from the Falls of the Ohio, near Louisville,
in America, and which I received likewise, some years ago, from Herr F. Roemer, the
ribs are small, in some places bifurcated, and numbering about thirty-four in each valve.
Some of our British examples bear, also, a certain resemblance to the Sperif. socialis of
Krantz, from the Devonian beds of Menzenberg ;’ but it is very difficult to be certain
while comparing such imperfect distorted internal casts.

SPIRIFERA UNDIFERA, /. Roemer. Pl. VII, figs. 1—10.

SPIRIFER UNDIFERUS, F. Roemer. Rheinisch. Uebergangsgeb., p. 72, pl. vi, fig. 6, 1844.
— — Schnur, in Dunker’s Paleeontographica, vol. iii, p. 204, pl. xxxiv,
fig. 34464, 1853.
— -- Sandberger. Die Brachiopoden Rheinischen Schichtensystems,
p. 18, pl. xxxi, fig. 8, 1855.

Spec. Char. Shell transversely or longitudinally oval; hinge-line less than the width
of the shell ; cardinal angles rounded ; dorsal valve moderately convex ; mesial fold broad,
more or less sharply defined, of small elevation, and either slightly longitudinally depressed
or obtusely rounded. From sixteen to twenty-eight flattened or but slightly rounded ribs
ornament the surface of each valve. Ventral valve rather deeper than the opposite one ;
sinus broad, varying in depth, with one or two faintly marked longitudinal ribs on either
of its sides; beak tapering, moderately produced and incurved; area triangular, wider
than high; fissure partly arched over bya pseudo-deltidium. The surface of the valves is
regularly crossed by numerous fine, contiguous, concentric, serrated ridges, &c. Pro-
portions variable ; three specimens have measured—

Length 14, width 16, depth 10 lines.

Ne ish ot, Saree ec
aU gs MU. LTC ay

' «Ueber ein neues bei Menzenberg aufgeschlossenes Petrefakten-Lager in den Devonischen Schichten,’
tab. viii, fig. 3.

SPIRIFERA. 37

Obs. Many examples of this very variable species bear so great a general resemblance
to the Carboniferous Sp. ovalis, and to its transverse variety, Sp. hemispherica, M‘Coy,
that I am in no way convinced we are justified while making use of a distinctive denomi-
nation for the Devonian shell.

It has been urged that, in perfectly preserved examples of Sp. undifera, the surface is
regularly crossed by numerous concentric, contiguous strie or ridges, while in Sp.
ovalis the surface is smooth ; but it must likewise be borne in mind that we but very rarely
meet with any Carboniferous shells so perfectly preserved as to exhibit their delicate outer
surface, the larger number being decorticated ; and this is also the condition in which we
find almost all our British specimens of Sp. undifera.

Having requested Messrs. Young and J. Thompson to kindly search for some well-
preserved examples of the Carboniferous Sp. ovalis, they were so fortunate as to find one
or two at Corrieburn and Brockley, in Scotland, in which the outer surface was closely
covered with numerous fine concentric striz or ridges, very nearly resembling those
observable in Sp. undifera.

Sp. undifera is a common shell in the Middle Devonian limestone of Woolborough
Quarry, near Newton Abbot, and has been also found in that of Barton and Lummaton,
near Torquay. On the Continent it occurs in the Eifel, in Nassau, at Ferques, &c.

SPIRIFERA UNDIFERA, var. UNDULATA, F. Roemer. Pl. VIII, figs. 11—14.

SprRIFER curvaTus, Schloth., var. uNDULATUS, F. Roemer. Rheinisch. Uebergangsgeb.,
p- 70, pl. iv, fig. 5, 1844.
— UNDIFER, Schnur, in Dunker’s Paleeontographica, vol. iii, p. 204, pl. xxxiv,
fig. 9 gand4, 1853.

Spec. Char. Shell transversely oval; hinge-line shorter than the width of the shell;
cardinal angles rounded ; dorsal valve convex ; mesial fold simple, wide, divided along the
middle by a shallow, longitudinal depression or groove, each valve beg ornamented with
from twenty to thirty rounded or slightly angular ribs, of which (in some specimens) a certain
number are due to the bifurcation or intercalation of additional ribs at variable distances
from the beaks. Ventral valve rather deeper than the opposite one, with a sinus of
variable width and depth, flattened along the middle, and with one or two feebly marked
ribs along its sides ; beak moderately produced and incurved ; area triangular, of moderate
size. Surface of the shell regularly crossed by numerous concentric ridges, as in the type
undifera. Proportions variable.

Length 18, width 25, depth 14 lines.

Obs. After very considerable hesitation and uncertainty, I have ventured to refer figures
11 to 14 of our plate to a well-marked variety or modification in shape of Sp. uadifera,
and this notwithstanding the bifurcation and intercalation of some of the ribs, which is

38 BRITISH DEVONIAN BRACHIOPODA.

not a character or feature of Roemer’s type. I have been led to this impression from the
study of fig. 9, g and/, of Schnur’s Sp. wndifera ; and it appears to me that Dr. Sandberger
is, perhaps, mistaken while excluding this modification from the varieties of the last-named
species. I possess, likewise, a similar specimen from the Eifel, sent me some years ago by
Herr F. Roemer, and labelled Sp. curvatus, Schl., var. undulatus, F. Roemer, and this,
although quite distinct from Schlotheim’s figures of Sp. curvatus, which represents a
smooth shell without lateral ribs, does closely resemble some varieties of the shell we are
at present describing. I may, however, be mistaken in my appreciation of this matter, but
have been unable to identify the shell with any other known Devonian species, and could
hardly venture to apply to it a new specific denomination. When we examine a large number
of specimens of Sp. wndifera and of the variety (?) undulata, we can perceive a far greater
connection between the two than the necessarily limited selection of illustrations will here
convey, and this leads me to believe that the whole series of specimens figured in PI. VII.
do probably belong to a single but variable species. We find similar modifications to
occur with the Carboniferous Sp. ovalis, Sp. pinguis, and its variety Sp. rotundata.
Indeed, the resemblance between these Devonian shells and those last named are often
so very striking as to almost lead one to believe that they are all mere modifications in
shape of a single species.

Sp. undifera, var. undulata, occurs plentifully in company with Sp. uadifera in the
Middle Devonian limestone of Woolborough Quarry, near Newton Abbot.

SPIRIFERA NUDA, Sow. PI. IV, figs. 17—24.

SPIRIFERA NUDA, Sow. Trans. Geol. Soc., 2nd series, vol. v, pl. lvii, fig. 8.
— PULCHELLA, Sow. Ibid., fig. 9.
— NuDA, Phillips. Pal. Foss., p. 78, pl. xxxi, fig. 138, 1841.
SPIRIFER NuDUS, F’. Roemer, in Dunker’s Paleeontographica, vol. v, pl. iv, fig, 20, 1855.

Spec. Char. Shell transversely semicircular, wider than long ; dorsal valve moderately
convex; mesial fold smooth, sharply defined, but of small elevation, one or two rounded
ribs existing on either of the lateral portions of the valve close to the mesial fold, the
remaining unoccupied lateral space being smooth ; hinge-line shorter than the width of
the shell; cardinal angles rounded. Ventral valve deeper than the opposite one, with a
shallow sinus, and one or two ribs on either side; beak prominent, angular, more or less
bent backwards, with its extremity incurved ; fissure partly closed by a pseudo-deltidium.

Length 11, width 13 lines; but the shell is usually smaller.

Oés. 'Uhis interesting species varies to some extent, on account of the greater or
smaller proportions of its area and number of ribs. In some specimens the mesial fold
and sinus are alone observable, all the remaining portion of the valves being smooth (fig.
17). In other examples (figs. 19—21) there exists one rounded rib on either side of the

SPIRIFERA. 39

mesial fold, while in some specimens the number is two on each side. The ribs on the
lateral portions of the valves are also more or less sharply defined in different specimens.
After comparing the original examples of Sowerby’s Sp. nuda with those of the same
author’s, Sp. pulchella (Sowerby’s types being preserved in the Museum of the Geological
Society), I arrived at the conclusion that the last-named shell is only a small variety or
condition of the first. In Sowerby’s two examples which we have figured (23, 24) it will
be seen that the same disposition of ribs as described for Spy. muda may be observed in
Sp. pulchella. We must not omit to call attention to the great similarity of character
existing between the Middle Devonian species and the Carboniferous Sp. triradialis (vol.
i, p. 49, pl. ix, figs. 4—12), the same disposition of ribs being prevalent; but the
Carboniferous shell is usually less transverse, and its beak smaller and more incurved.
Spirifera nuda and its variety Sp. pulchella occur in the Middle Devonian limestone of
Dockyard, near Plymouth. It is found also at Woolborough, near Newton Abbot, at
Barton, and Lummaton, near Torquay, and at Dartington, near Totness, in Devonshire.

SPIRIFERA CURVATA, Sch/oth. (sp.). PL. IV, figs. 29—32, 33 (?), 34 (?); Pl. IX, figs. 26, 27.

TEREBRATULITES CURVATUS, Schlotheim. Nachtragen zur Petrefactenkunde, pl. xix, fig. 2,

1822.
SPrRIFER cuRvATUS, Buch. Ueber Delthyris, p. 52, 1837.
Detruyris — Goldf. in Von. Dechen’s Handb., p. 526.
SPIRIFER — Schnur. Uebergangsgebirge der Eifel, Brachiopoden, in Dunker’s

Paleeontographica, iii, p. 208, pl. xxxvi, fig. 3.

Spec. Char. Shell variable in shape, transversely oval, and usually wider than long ;
valves almost equally convex, with a mesial fold of variable elevation in the ventral valve,
to which corresponds a sinus in the opposite one; hinge-line shorter than the width of
the shell; cardinal angles rounded ; beak incurved ; ventral area triangular ; dorsal one
linear ; fissure partly covered over by a pseudo-deltidium ; surface closely crossed by rows
of imbricated, serrated ridges. Proportions very variable ; two specimens have measured—

Length 19, width 24, depth 18 lines.

4 POs ates ROS Shih oy

Oés. In general shape, the larger number of our British specimens of Sp. curvata are
undistinguishable from Sp. glabra; and,indeed, had we only the decorticate examples usually
met with in our Middle Devonian rocks (Pl. IV, figs. 29—32), we should at once identify
them with Martin’s Carboniferous shell. The difference, as far as we can at present
perceive, appears to rest in the external surface or sculpture; for in well-preserved
examples of Sp. curvata the shell is finely striated and closely imbricated, and decussated
by numerous transverse or concentric, finely serrated ridges (Pl. IX, figs. 26, 27),
similar in character to those which may be seen in Sp. disulcata, Sp. undifera, Sp. lineata,

40 BRITISH: DEVONIAN BRACHIOPODA.

and many other species. Hitherto this kind of sculpture has not, as far as I am aware
of, been observed in any specimens of Sp. glabra, although numerous concentric lines of
growth traverse its surface ; hence the, at present, supposed specific difference. Schlotheim’s
figures are not good, and afford but a very imperfect idea of the shell; but those by Schnur
show well the characters of the species, and are quite similar to the more perfect examples
we pick up in Great Britain.

Sp. curvata is a common fossil in the Middle Devonian limestones of Woolborough
and Chircombe Bridge, near Newton Abbot, at Ramsleigh, near Ogwell, Barton,
Lummaton, and Hope’s Nose, near Torquay, Dartington, near Totness, Ilfracombe, &c.,
in Devonshire.

In the Lower Devonian grits of Looe, in Cornwall, occur numerous compressed casts
(Pl. IV, fig. 33), which we have, with much uncertainty, referred to the species under
description. It is possible that the fragment from Hope’s Nose (PI. IV, fig. 16), described
by Phillips under the name of Sp. microgemma (‘ Pal. Foss.,’ p. 68, pl. xxvii, fig. 116), may
belong to Sp. curvata, but from such a fragment we cannot form any decided opinion.

SPIRIFERA NEWTONIENSTS, (n. sp.?) Pl. IX, fig. 21.

Spec. Char. Shell of a somewhat square or pentagonal shape, longer than wide,
smooth ; lateral margins almost parallel, slightly indented in front ; hinge-line as long as
the width of the shell. Ventral valve convex; sinus of moderate width and depth; beak
nearly straight, acute; area triangular, flat; fissure large. Dorsal valve semicircular, not

so deep as the opposite one; mesial fold obscurely defined, rounded, and of moderate
elevation.

Length 20, width 18 lines.

Obs. A single specimen of this species (?) from the Middle Devonian limestone of
Woolborough Quarry, near Newton Abbot, is preserved in the British Museum. The
length of its hinge-line, as well as the shape of its beak and area, will hardly allow us to
consider it as a mere variation of shape of Sp. glabra or Sp. curvata; and as we are not
acquainted with any other smooth Devonian Spirifer with which it can be identified, I have
reluctantly ventured to describe the shell as a new species,

SPIRIFERA. 4]

SprriFeRA Urit, Fleming, 1828. PI. IV, figs. 25—28.

Sprrirer Unit, Fleming. British Animals, p. 376, 1828.
ATRYPA UNGUICULUS, J. Sow. Trans. Geol. Soc., 2nd ser., vol. v, pl. liv, fig. 8.

SPIRIFERA — Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 69,
pl. xxviii, fig. 119, 1841.
SPIRIFER a A. Roemer. Dei Versteinerungen des Harzgebirges, pl. iv, fig. 22.

Martinia Crannyana, King. Cat. of the Organic Remains of the Permian Rocks of
Northumberland and Durham, 1848; and Mon. of English Per-

mian Fossils, p. 134, pl. x, figs. 11—13, 1350.
Sprrirera Uri, Dav. Mon. Carb. Brach., p. 58, pl. xii, figs. 13, 14; and p. 267, pl. liv
figs. 14, 15. ,

Spec. Char. Shell small, suborbicular, rather wider than long; hinge-line shorter
than the greatest breadth of the shell; cardinal angles rounded. Dorsal valve semicircular,
slightly indented in front, with a narrow hinge-area; nearly flat or but slightly convex—
most so at the umbone—with a shallow mesial furrow, commencing at a short distance
from the umbone and extending to the front. Ventral valve much more convex and deep
than the opposite one, with a comparatively large, incurved beak, and longitudinal furrow,
commencing at the extremity of the beak and extending to the front. The area is
triangular and of moderate length and width, the fissure being partly arched over by a
pseudo-deltidium. The external surface, where perfect, is covered with small spinules.
Dimensions variable.

Length about 4, width 43, depth 2 lines.

Obs. ‘This little species has been fully described in the second volume of this work ;
therefore all we need now repeat is, that the Permian, Carboniferous, and Upper Devonian
specimens are identical in shape and character, as a comparison of specimens, as well as of
the figures, will sufficiently prove. This identity has been likewise recognized by Professor
Morris, at p. 154 of his ‘Catalogue,’ by Messrs. Salter, Howse, Kirkby, De Verneuil, and
myself, and by Sir R. Murchison, who does not omit to mention, at p. 299 of the second
edition of his admirable ‘Siluria,’ that Spirifera Urit, Sp. disjuncta, and Orthis interlineata,
are found associated together, and that they are common fossils of the Barnstaple or
Marwood and Pilton series, as well as in that of South Petherwin; these beds being
referred by the above-named and celebrated geologist to the Upper Devonian of this
country.’ .

1 This is not the place to discuss the much controverted question relating to the real or supposed value
or claims of the Devonian formation, that is to say, whether it should or not be considered a distinct and
independent system; but, as I have often to make use of the provisional terms “‘ Upper” and “ Middle
Devonian” with reference to the fossils described in this monograph, a few lines of explanation may now
appear to be absolutely required.

Some geologists have gone so far as to suggest that the so-termed Devonian, as a system, could be ad-

F

42 BRITISH DEVONIAN BRACHIOPODA.

Sp. Urii is exceedingly common in the shape of casts in the brown grits of Marwood,
Barnstaple, and Braunton, in Devonshire ; and it occurs also in what Mr. Salter considers

vantageously dispensed with; that the lower portion of the strata representing the Siluro-Carboniferous
interval should be given to the Silurian, while the upper portion, including the Petherwin, Marwood, and
Pilton beds, should form part of the Carboniferous system. The strong notion of the equivalency of the
Devonian and Lower Carboniferous is growing up in some quarters, as well as that of a close affinity and
representativeness of the Devonian and Carboniferous forms; but such views are far from having been
hitherto satisfactorily proved. At the time I first began my researches among the Brachiopoda, I believed
to some extent, along with many others, in the supposed independence of geological systems ; but, as I pro-
gressed with my geological and paleontological studies, I gradnally began to doubt the existence of any
absolute paleontological demarkation between any contiguous geological systems, and was led to concur with
M. De Verneuil, who attaches less importance than do many geologists to those geological and palzontological
divisions of the crust of the globe, which he believes to be more in our idea than in nature, and conforming
more to the actual state of science than to its complete development. I therefore hasten to declare, that
I do not consider the Devonian formation to be an independent system any more than I do the Carboni-
ferous and Permian ; all three appearing to me to be connected by a gradual passage of certain species.
I am, therefore, quite prepared to admit that a certain number of Brachiopoda have passed from what is
termed Upper Devonian into Lower Carboniferous ; and some species from the other classes are common to
the two periods; certain bivalved Entomostraca, for instance, are declared by Mr. R. Jones to be identical,
&c. But for all that, if for nothing else but the sake of convenience and reference, I should feel disposed
to retain the divisions introduced by Sir R. Murchison and other geologists, when deprived of the fallacious
idea of their absolute independence.

Mr. J. Beete Jukes informs me that he considers the Carboniferous Slate of Cork to be absolutely con-
temporaneous with the Carboniferous Limestone of the rest of Ireland, and that the Marwood and Pilton
grits of North Devon are also the sandy representatives of the Carboniferous Limestone, and therefore not
Devonian at all. The study I have recently made of some of the Brachiopoda collected by Mr. Jukes
and the Irish Geological Survey, in the slaty and sandy beds which lie between thick Carboniferous Limestone
and genuine Old Red Sandstone at Scariff, and in other localities in the county of Cork, would lead me
to agree with Mr. Jukes that these brown grits and slates may be contemporaneous with or equivalent
to the North Devon, Marwood, and Pilton beds, whether they be considered as Upper Devonian or as
Lower Carhoniferous. ‘They possess several fossils in common, such as Spirifera disjuncta, Sp. cristata,
var., an Athyris, probably referable to A. concentrica, Rhynchonella pleurodon, and some species of Orthis,
Chonetes, and Preductus, to be hereafter described. The nature, however, of these fossils, as well as the
presence of Cyrtina heteroclita, associated with Spirifera disjuncta in the grits of Reenydonegan Point, at
the head of Bantry Bay, would make me pause awhile prior to recognizing these beds to be, strictly speak-
ing, Carboniferous, or until it may have been satisfactorily proven that what geologists have hitherto
considered as Upper Devonian should in reality form part and parcel of the Carboniferous. Mr.
Jukes informs me, moreover, that the beds at Reenydonegan Point, which contain so interesting an
assemblage of what I should consider Upper Devonian and Carboniferous Brachiopoda, is up near the top
of what he terms the Irish Carboniferous Slate, or 4000 or 5000 feet above the top of the Old Red Sand-
stone, and that they are full of Phillipsia pustulosa, the common Carboniferous Trilobite, and other fossils,
apparently common Carboniferous species. These Irish and North Devon grits would therefore, on
paleontological grounds, seem to be intermediate beds, connecting the Devonian with the Carboniferous ;
for there can be no doubt that, taken as a whole, the fauna of the Devonian formation is distinct from that
of the Carboniferous, although the two formations may be connected by a gradual passage and mixture of
Devonian and Carboniferous species ; or, in other words, it is no doubt the truth that there are certain
species of fossils common to Devonian beds and the Carboniferous system ; but it is not the whole truth, for

SPIRIFERA. 43

to be lower beds at Petherwin, in Cornwall. Herr A. Roemer has also found larger
examples of this shell in the Devonian beds of Griind, in the Hartz.

? SpiriFeRa LinEata, Martin (sp.). Pl. IV, figs. 183—15, 16.

CoNncCHILIOLITHUS ANOMITES LINEATUS, Martin. Petref. Derb., pl. xxxvi, fig. 3, 1809.

TEREBRATULA LINEATA et IMBRICATA, Sowerby. Spirirer Martini, Fleming.

SPIRIFERA LINEATA, Phillips. Pal. Foss. of Cornwall, Devon, and West Somer-et, p. 70.
pl. xxviii, fig. 120, 1841.

MICROGEMMA, Phillips. Ibid., p. 68, pl. xxvii, fig. 116.

~—

there are also some species common to Devonian beds and the Stlurian system; whilst by far the greater
number are neither Silurian nor Carboniferous, but intermediate forms, that is, they represent an inter-
mediate period, if it be possible for fossils to do so. The results of Mr. Jukes’ examination of these Irish
beds, and of their fossils, will be found in the ‘ Explanations of the Geological Survey of Ireland ;’ and
at pp. 215, &c. (also foot-note, p. 185) of the same author’s ‘School Manual of Geology.’ This subject
will, however, require much further examination, and it will be necessary for all the classes of fossils
found in the North Devon and South of Ireland brown grits aud slates to be carefully compared with
Carboniferous types, before any positive determination relative to the age of these beds be finally settled.
In Ireland we appear to have, first, some Upper Silurian rocks, full of marine mollusca, Brachiopoda,
&c.; then, a very thick formation, of what Mr. Jukes terms Dingle beds, resting conformably on the upper
Silurian, but covered unconformably by genuine Old Red Sandstone, neither containing any Brachiopoda ;
above this, a very thick succession of slaty and sandy beds or grits, full of marine fossils, and containing
a mixture of Devonian and Carboniferous species of Brachiopda; and above part of this, again, beds of
Carboniferous Limestone, full of genuine Carboniferous fossils aud Brachiopoda ; while other parts have
no limestone over them, but in some places shales, that appear to be Coal-measures, the parts not covered
by the limestone being much thicker than those that are.
Mr. Jukes informs me that he has now arrived at the following general conclusions :
Ist. That the uppermost bed of the trne Old Red Sandstone was in existence before any of the beds
containing marine Devonian fossils were deposited.
2nd. That the Devonian fauna was contemporaneous with the Carboniferous, the terms reaily
indicating a geographical and not a chronological distinction. He believes this will ultimately
be found to be true for America as well as Europe.
3rd. That the so-called Old Red Sandstone of Wales and Scotland belongs to two periods, distinct
in their forms of life, the one (containing Cephalaspis, &c.) belonging more properly to the
Upper Silurian, the other being more closely connected with the Carboniferous,
4th. He would limit the term Old Red Sandstone to the latter; and his first conclusion will then
show the confusion produced by using the words “Old Red Sandstone”? and ‘‘ Devonian” as
synonymous.
In his valuable paper “On the Upper Old Red Sandstone and Upper Devonian Rocks ” (‘ Journal of
the Geol. Soc. of London,’ vol. xix, p. 490, &c., 1863), Mr. Salter, with the concurrence of Sir R.
Murchison, refers the Marwood and Pilton beds of North Devon to the Upper Devonian {Verneuilii-
Schiefer, &c.). The Petherwin and Landlake group he considers to constitute a lower band also of the
Upper Devonian, but not to represent that of Barnstaple or of the Marwood and Pilton series, these last
being the equivalents of the Clymenien-Kalk or Cypridinen-Schiefer of the Prussian geologists, and, perhaps,
of the red slates of Morte Bay ; so that, in Mr. Salter’s opinion, the Marwood and Pilton Beds overlie the
Petherwin group.

44 BRITISH DEVONIAN BRACHIOPODA.

Spec. Char. Transversely oval, or suborbicular ; hinge-line much shorter than the width
of the shell; cardinal angles rounded ; beaks more or less approximate, and considerably
incurved. Ventral valve gently and evenly convex, rarely exhibiting any mesial elevation.
Dorsal valve rather deeper than the opposite one, uniformly convex, or presenting a shallow
longitudinal depression, apparent only in the proximity of the front, or extending to the
extremity of the beak. Area small, with lateral margins obscurely defined; fissure
triangular, partially covered by a pseudo-deltidium. Surface of both valves marked by
numerous concentric ridges, rarely more than a line apart in any place, but usually very
much closer, and from which projected numerous closely. packed spines, forming a series
of spiny fringes overlapping each other all over the shell. Proportions variable.

Length 12, width 13, depth 8 lines.

Oés. Specimens which appear to agree in shape with Martin’s Sp. /ineata have been
found in the Middle Devonian limestone of Woolborough Quarry, near Newton Abbot
(fig. 13); while other examples are described and figured by Phillips under the same
denomination, from the Upper Devonian beds of South Petherwin and.Landlake (figs. 14,
15). In the specimens I have been able to examine, the outer shell-surface was very

Mr. Jukes, on the other hand, informs me that an exploration in North Devon, in 1862, showed him
that the red and green slates and sandstones of Morte Bay were precisely like the “‘ Upper Old Red” beds
of the western part of Cork, and the section above them, round Baggy Point into Croyde Bay, exactly like
the section which always comes above the Upper Old Red in West Cork. He can have no doubt, then, that
the beds at the southern end of Morte Bay are the Upper Old Red, in which no trace of a marine fossil has
yet been found, either in North Devon or South Cork. He also says that he could see no stratigraphical
reason for believing that the Petherwin beds were above or below the Pilton beds. The Pilton beds rise
from underneath the Coal-measures on the north and the Petherwin beds on the south, witliout any
evidence, so far as he could see, of any unconformability between the Coalmeasure-slates above and the
others below in either locality; neither was the lithological difference between the beds at the two localities
very striking, nor greater than might naturally occur in a distance of twenty-five miles. This intervening
distance is occupied by a very disturbed basin of crumpled Coal-measures, which also greatly resemble the
Coal-measures of the south of Ireland.

The Middle Devonian of the Eifel would, anyhow, be represented in England by the Plymouth, Wool-
borough, Torquay, Dartington, and cther similar deposits, and may, perhaps, be susceptible of being divided
into several horizons. At Torquay we would, according to Mr. Salter, have the Spirifer-sandstone group of
the Rhine; in other places we certainly have the Stringocephalen-Kalk and Calceola-Schiefer or Lenne-
Schiefer (Eifel-Kalk of the Prussian geologists). The Lower Devonian Mr. Salter considers to be, perhaps,
the equivalent of the Old Red Sandstone; the ‘‘Tilestones,’’ or Ledbury Shales, being, according to his
views, the Lowest Devonian.

Mr. Pengelly informs me that, if the entire Siluro-Carboniferous interval is represented by the
Old Red Sandstone, as Mr. Jukes would appear to hold, it will follow, he thinks, that the Devonshire
lower slates, 7. e. those below the Torbay, Newton, and Plymouth limestones, are the only Devonian beds
we have, all above being Carboniferous; and that, should Mr. Jukes carry out his threat of handing
over to the Carboniferous system the Upper Old Red, the lower slates must go too, as he believes them
to be on the same horizon. Mr. Pengelly’s impression, however, is that the Old Red Sandstone represents
the Lower, and the Devonshire or Damnonian beds the Upper, Devonian Period, or Siluro-Carboniferous

SPIRIFERA. 45

imperfectly preserved ; but Phillips describes those he has seen and figured as “ Concen-
trically undulated, with concentric, raised, small ridges, across which run fine, interrupted,
longitudinal lines, producing a minute crenulation, or even granulation;”’ and these
markings are, no doubt, due to the concentric spiny fringes which cover the surface of the
shell, and which I have already had occasion to describe and illustrate at p- 225, and
Pl. LI, fig. 15, of my ‘Monograph of British Carboniferous Brachiopoda.’ One of the
specimens resembled Spirifer concentricus, Schnur, from the Hifel.

Sp. microgramma, Phillips (fig. 16), I have not been able to examine ; and, as the very
imperfect figure represents only a portion of one of the valves, it is impossible for me to
offer any decided opinion as to its specific claims. I will, however, here reproduce the
original description :

“ Character.—Sub-orbicular, rather depressed, with a slight mesial undulation (convex
on the lesser valve). Surface thickly and finely striated from the beaks, the stria being
crossed by the rather conspicuous edges of many lamine of growth ; at the intersections
of these two sets of lines are minute rounded eminences.

“The analogues of this species are fossils of the Mountain-limestone, viz., Sp. imbricata,
Sp. mesoloba, &c. Having collected two agreeing specimens from different districts, I am
desirous of calling attention to it, as at least a definite and delicate variety of Sp. imbricata.
Loc.—In North Devon— Brushford ; in South Devon— Hope, near Torquay.”

_ It must be remembered that I have already shown, at p. 64 of my ‘ Carboniferous
Monograph,’ that Sp. imbricata and Sp. mesoloba are synonyms, or simple modifications in
shape, of Sp. /éneata, and that we are, therefore, so far justified in provisionally locating
Phillips’s so-termed species among the synonyms of Martin’s shell.

interval, as in the following scheme (the Barnstaple group being omitted, as belonging to the Carboni-
ferous rather than to the Devonian system, or, perhaps, forming passage-beds between the two).

CARBONIFEROUS.

Petherwin beds.

Dartmouth or Upper Slates: the “Dartmouth” group may be on the horizon
of the ‘*Petherwin”’ series, but it is not easy to determine this point, as the
former has yielded but few fossils.

Torquay or Limestone beds.

Meadfoot or Lower Slate, and Upper Old Red.
Middle Old Red.

Lower Old Red.

UPPER SILURIAN,

DEVONIAN.

Old Red. | Damnonian.

And that it may be true that ‘‘nobody has ever yet described any place where the South Devon beds
lie above rocks which contain undoubted Upper Silurian,’ and below others containing Carboniferous
Limestone fossils; but that surely we must not expect to find an unbroken sequence everywhere.

46 BRITISH DEVONIAN BRACHIOPODA.

SPIRIFERA SIMPLEX, Phillips. PI. VI, figs. 18—22.

SPIRIFERA SIMPLEX, Phillips. Paleozoic Fossils of Cornwall, Devon, and West Somerset,
p. 71, pl. xxix, fig. 124, 1841.
SPIRIFER — Roemer. Die Versteinerungen des Harzgebirges, pl. iv, fig. 11.
— — Sandberger. Die Brachiopoden des Rheinischen Schichtensystems in
Nassau, pl. xxxul, fig. 10, 1855.
== = Quenstedt. Hand. der Petrefactenkunde, pl. xxxviii, fig. 22, 1851.

Spec. Char. Obtusely pyramidal, wider than long ; hinge-line straight, slightly shorter
than the width of the shell. Ventral valve deep, pyramidal, and longitudinally divided by
a sinus, which commences at the extremity of the beak and extends to the front. Area
triangular, as wide as long, and situated at a right angle to the general level of the dorsal
valve ; fissure narrow, arched over by a pseudo-deltidium. Dorsal valve semicircular,
evenly and uniformly convex, with or without a slight elevation near the front. Surface
smooth. Proportions variable.

Length 14, width 18, depth 12 lines.

Oés. This species is easily distinguishable from other British Devonian species. It
occurs in the Middle Devonian limestone of Woolborough, near Newton Abbot, and has
also been found in limestone near Plymouth, in Devonshire. On the Continent it occurs
abundantly at Paffrath, near Cologne, in Nassau, the Hartz, &c.

Sub-genus—Spinirerina, D? Orbigny.

SpmIRIFERINA cRIsTATA, Schloth. (sp.), var. Pl. VI, figs. 11—15.

TEREBRATULITES CRISTATUS, Schlotheim. Beitr. z. Naturg. d. Verst, in Akademie der Wissen-
schaften zu Miinchen, pl. i, fig. 3, 1816.

Sprrirera cristata, Dav. Mon. British Permian Brachiopoda, p. 17; and Carboniferous
Mon., pp. 38 and 226,

Spec. Char. Shell transversely subrhomboidal ; valves almost equally convex ; hinge-
line as long as or slightly shorter than the width of the shell; cardinal angles acute or
slightly rounded ; ventral area triangular ; fissure partly arched over by a pseudo-deltidium ;
beak incurved. The mesial fold in the dorsal valve is usually formed of a single rib,
flattened along the middle, and to it corresponds a sinus in the opposite one. The remain-
ing portion of each valve is covered with from eight to twelve angular ribs, the surface
of the shell being also (in perfect specimens) intersected at close intervals by numerous

SPIRIFERINA. 47

concentric lamine of growth. Shell-structure perforated by large canals. Proportions
variable ; two Devonian specimens have measured :

Length 8, width 11 lines.

Oés. The question relating to the origin and recurrence of the Spiriferina we are at
present describing is one of some difficulty, demanding considerable attention and further
research. It is an exceedingly variable shell, being small (adult) in some localities or
strata, while in others it has attained considerably larger dimensions. Thus, at Looe, in
Cornwall, the shell is large, while at Dartington it is apparently always of small size. It
is my strong impression that we must look for its first appearance or origin in the Silurian
time, and that it continued to be represented, with some slight modifications, in the
Devonian, Carboniferous, Permian, and perhaps up to the Jurassic period (?). One thing
certain is, that, having compared some of our Scottish Carboniferous specimens, for example,
with the Silurian Azomia crispa of Linneus,' I could detect hardly any modification in
shape or character. Other examples strongly resemble De/thyris sulcata, Hisinger, as
well as some other so-termed closely related American forms. I will not, however, at
present, go further into the question, but content myself by stating that our British
Devonian specimens appear to be specifically the same as those we find so abundantly in
the Carboniferous and Permian periods, and to which Schlotheim has applied the denomi-
nation of crisfata, and Sowerby that of octoplicata, At Looe distorted internal casts are
abundant ; and it occurs in company with Uncites gryphus in the Dartington dolomitic
limestone of the Middle Devonian time. Some specimens have also been found in the
Pilton and Marwood beds. As we have already had occasion to observe, it is difficult
to obtain from the Paleozoic limestones specimens with their outer surface perfectly pre-
served, and it is usually from soft shales that we must seek for examples preserving their
outer sculpture; this is why the concentric laminze which cover the surface of the shell,
and which sometimes overlap each other in perfectly preserved specimens of Sp. cristata,
and its Carboniferous and Devonian representatives, are not commonly seen; this, in
addition to the variability in the number of ribs, has led to the fabrication of several so-
termed species. Sp. aculeatus, Schuur, appears also to be very closely related to the shell
under description.

1 This is not the place, however, to enter more deeply into the question relating to the Silurian form.
In his ‘ Ipsa Linnzei Conchylia,’ by 8S. Hanley, 1855, we find at p. 128 the following statement :—‘‘T cannot
find a specimen in the Linnean Cabinet to which the whole of the description will apply. The Swedes
(Wahlenberg, Nilsson, Hisinger) have handed down so many of the fossil species of our author in an un-
broken chain of tradition, confirmed in so many cases by the types in the collection of Linnzeus, that the
Spirifer recognized by them (Terebrat. crispa, Hising., ‘ Vet. Acad. Handl.,’ 1828, pl. vii, fig. 4 ; Delthyris
erispa, Dalman, ‘ Vet. Acad. Handl.,’ 1827, pl. iii, fig. 6; Hisioger, ‘ Lethzea Suecica,’ pl. xxiv, fig. 5) for
this species of Anomia may be accepted as such with some degree of confidence. (Sharpe, MS.) This
opinion is in harmony with that of Mr. Davidson ;” but the subject will be fully discussed in our mono-
graph of Silurian species.

48 BRITISH DEVONIAN BRACHIOPODA.

P SPIRIFERINA INSCULPTA, Phillips (sp.), var. Pl. VI, figs. 16, 17.

SprriFera INscuLpta, Phillips. Geol. of Yorkshire, vol. ii, p. 216, pl. ix, figs. 2 and 3, 1836.
SPIRLIFERINA — Dav. British Carb. Brachiopoda, p. 42, pl. vii, figs. 48—55, and
pl. lii, figs. 14, 15.

Spec. Char. Shell somewhat pentagonal, wider than long; hinge-line straight, and
usually slightly shorter than the width of the shell; cardinal angles rounded; area
triangular and slightly curved. Dorsal valve moderately convex, with from five to seven
strong angular ribs, of which the central one is the largest. Ventral valve slightly deeper
than the opposite one, with from four to six strong angular ribs, divided by a sinus of
greater depth ; beak incurved ; fissure partly arched over by a pseudo-deltidium. Surface
of the shell closely and regularly intersected by numerous concentric lamine of growth.
Shell-structure perforated.

Length 7, width 8, depth 5 lines.

Obs. It is possible that the shell under description may be nothing more than a
modification of Sp. cristata, with fewer and stronger ribs. It bears also some resemblance
to certain examples of Spiriferina crispa, but more so to the Carboniferous Sp. inseulpta,
with which it is, at any rate, provisionally identified.

It occurs in the Middle Devonian limestone of Lummaton, near Torquay.

Spiriferina laminosa, M‘Coy, has been stated by Mr. Salter to occur in the Marwood
beds of North Devon; but I have not been fortunate enough to procure examples.

Genus—Cyrrtina, Dav.
CyrtIna nererocuita, Defrance, (sp.)' Pl. 9, figs. 1—16.

CALCEOLA HETEROCLITA, Defr. Dic. Se. Nat., vol. Ixxx, fig. 3, et De Blainville, Malaco-
logie, pl. lvi, fig. 3.
SPIRIFER HETEROCLYTUS, Buch. Ueber Delthyris oder Spirifer und Orthis, p. 40, 1837;
and Mém. Soc. Géol. de France, vol. iv, p. 186, pl. viii, fig. 11,
1840.
— weTEROcLITA, Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 72,
pl. xxix, fig. 125, 1841.
— SUBCONICA, var. Sowerby (not of Martin). Trans. Geol. Soc., 2 ser., vol. v, pl. lvii,
fig. 10.
Sprrirera (Cyrtra) weTerocuita, M‘Coy. British Pal. Foss., p. 377, 1852.

1 Some palzontologists have spelt the term Heteroclitus with a y (Heteroclytus), but the first is the
correct spelling. Heteroclitus means originally a verb irregularly declined ; in Greek, érepo«Aéros, with
_the « short.

CYRTINA. 49

SPIRIFER HETEROCLITUS, Quenstedt. Handbuch der Petrefactenkunde, pl. xxxviii, fig. 21,
1851.
— — Davidson. General Introduction, pl. vi, figs. 63, 64, 1853.
_— — Schnur, in Dunk. u. Von Meyer’s Palzeontograph., vol. ili, pl. xxxv,
fig. 6, 1853.
_ _ Sandberger. Die Brachiopoden des Rheinischen Schichtensystems
in Nassau, pl. xxxii, fig. 8, 1855.
CYRTINA HETEROCLITA, Dav. Mon. Carb. Brach., p. 67, 1858.

Spec. Char. General shape acutely pyramidal ; hinge-line as long as, or alittle shorter
than, the width of the shell. Ventral valve pyramidal, and much deeper than the opposite
one ; area flat, triangular, very large, and bent back at various angles to the general
surface of the dorsal valve; fissure long, narrow, and almost entirely arched over by a
pseudo-deltidium ; sinus deep, angular, extending from the extremity of the beak to the
front. Dorsal valve semicircular, with a prominent, more or less angular, fold. Each
valve is ornamented with from six to sixteen or more angular ribs. In the interior of the
ventral valve two contiguous vertical septa coalesce into one median plate, which extends
from the extremity of the beak to within a short distance of the frontal margin, and then
diverges to form the dental plates, in a very similar manner to what we perceive in
Pentamerus. The median septum is continued as far as the under surface of the
deltidium, although this is not always seen in our specimens. Shell-structure punctated.
Proportions very variable :

Length 5, width 7, depth 10 lines.

Obs. This important and characteristic fossil of the Middle Devonian limestones of
Great Britam and the Continent is exceedingly variable in shape, this being chiefly
occasioned by the greater or lesser development of the area, and of the number of ribs
with which the surface of the shell is ornamented. In some specimens the beak is also
twisted to one side or the other. It is a small species, but some French specimens
have attained twice the dimensions of any hitherto found in this country. In Devonshire
it occurs in Upper Devonian limestone, near Plymouth ; at Barton and Lummaton, near
Torquay ; Woolborough, near Newton Abbott; Dartington, near 'l'otness, and in coarse
limestone at Hagginton Hill, near Ilfracombe, North Devon. On the Continent it
is found at Ferques, in the Boulonnais (France); Chimay (Belgium); the Eifel, im
Nassau, &c.

Var. mMuutipiicata, Dav. Pl. IX, figs. 11—14.

SPIRIFERA cusPIDATA, Phillips (not of Sow.). Pal. Foss. of Cornwall, Devon, and West
Somerset, p. 72, pl. xxix, fig. 124%.

Spec. Char. Shell transverse, wider than long; lateral margins formmg attenuated
acute angles with the extremities of the hinge-line or area; dorsal valve semicircular,
G

50 BRITISH DEVONIAN BRACHIOPODA.

moderately convex, with a prominent angular fold; ventral valve pyramidal, deeper than
the opposite one; sinus angular, commencing at the extremity of the beak and extending
to the front ; area large, flat, triangular; fissure narrow, entirely arched over by a pseudo-
deltidium. ach valve is ornamented by from twelve to twenty small angular ribs, the
surface being likewise traversed by numerous concentric lines of growth.

Length 4, width 8, depth 5 lines.

Oés. I am much puzzled how to deal with this shell, for although closely connected to,
and probably nothing more than a modification in shape or variety of, Cyrtina heteroclita,
it presents certain differences which might lead one to imagine it almost a distinct species.
Indeed, Phillips has described and figured it as a small form of the Carboniferous Spirifera
cuspidata ; but from this it is not only specifically but also generically distinct, for its
internal dispositions agree with those we have already described for Cyrtina heteroclita.
Some specimens also appear to connect this variety with the typical forms of the species.

It may, therefore, be better to provisionally consider it a variety of C. heteroclita, with
the distinctive denomination of ‘ ma/tiplicata ;’ and I have figured a series of specimens
which will enable the reader to determine the question as he may think proper. ‘The
variety here described has been found at Barton and Lummaton, near Torquay.

Crrtina Demarut, Bouchard, MS. Pil. IX, figs. 15—17.

SprRIFERA suBCONTCA, Phillips (not of Martin nor Sowerby). Pal. Foss. of Cornwall,
Devon, and West Somerset, p. 72, pl. xxix, fig. 126, 1841.

Spee. Char. Shell small, wider than long; hinge-lme about as wide as the shell ;
dorsal valve semicircular, moderately convex ; ventral valve pyramidal, much deeper
than the opposite one, with a sinus of moderate depth, to which corresponds a biplicated
mesial fold in the opposite one; about twelve simple ribs ornament the lateral portions of
each valve ; area large, triangular, situated at right angles to the general plane of the
dorsal valve; fissure narrow, arched over by a pseudo-deltidium ; shell-structure
punctated.

Length 3, width 4, depth 3 lines. Some specimens attained somewhat larger pro-
portions.

Oés. The longitudinal groove in the centre of the mesial fold serves to distinguish
this shell from C. heferochita. The interior arrangements appear to be similar to those of
the last-named species, the median septum in the ventral valve being continued as far as
the under surface of the deltidium, while the dental converging plates are fixed to its sides.
Mr. Lee found two specimens of this small shell in the Middle Devonian Limestone of
Barton, near Torquay ; and it has been often collected by Mr. Bouchard and by myself at
Ferques (France).

ATRYPA. 51

Cyrtina ? AMBLycona, Pizllips (sp.). Pl. IX, figs. 18—20.

TEREBRATULA AMBLYGONA, Phillips. Paleozoic Fossils of Cornwall, Devon, and West
Somerset, p. 88, pl. xxxv, fig. 160, 1841.

Spec. Char. Shell oblong, somewhat pentahedral, nearly as wide as long ; hinge-line
rather shorter than the width of the shell; dorsal valve slightly convex; mesial fold rather
flat, of small elevation, originally with one narrow rib, but gradually widening and forming
two additional ribs by bifurcation, or by the juxtaposition of a lateral rib; eight or ten
other simple ribs ornament the surface of the valve; ventral valve convex, deeper than
the opposite one; sinus shallow, rather flat, and composed of two ribs at its origin, but
these bifurcate at a short distance from the extremity of the beak ; the area is triangular,
rather large ; fissure narrow, arched over by a pseudo-deltidium. ‘Two specimens have
measured :

‘Length 7, width 6, depth 3 lines.
clit sit ala Y ial cane: sae

Ods. Having procured from Mr. Lee the loan of the figured type, and removed the
matrix which obscured the beak and a portion of the surface of the dorsal valve, I soon
perceived that the shell belonged either to Spirfera or Cyrtina, and not to Terebratula,
as had been supposed by Phillips. Not having been able to examine its interior arrange-
ments, I am uncertain whether it should be classed under Spirifera or Cyrtina, and have
therefore left it provisionally with the last-named sub-genus. ‘T'wo specimens were found
by Mr. Lee in the Middle Devonian Limestone of Barton, and I have another from Lum-
maton, near ‘Torquay.

Genus—AtryPa, Dalman, vel Spiricerina, D’ Orbigny.
) Lgny

Arrypa LENS, Phillips (sp.). Pl. X, fig. 1.

Ortuis LENS, Phillips. Paleozoic Fossils of Cornwall, Devon, and West Somerset, p. 65,
pl. xxvi, fig. 110% 2, 1841.
TEREBRATULA DIVIDUA, Schnur. Programm der vereinigten héhern biirger und provinzial
Gewerbeschule zu Trier, p. 6, 1851, andin Dunker und Von Meyer’s
Palzontographica, vol. iii, p. 179, pl. xxiv, fig. 2, 1853.
OrtHis LENS, D’ Archiac and De Verneuil. Description of the Older Deposits of the
Rhenish Provinces, Trans. Geol. Soc., 2d series, vol. vi, p. 396.
_ — Morris. Catalogue of British Fossils, p. 140, 1854.
Ortuis Eirutensis, J. Steininger. Geognostische Beschreibung der Eifel, p. 80, pl. v,
fig. 5, 1853.

Spec. Char. Shell small, compressed, longitudinally oval, notched in front ; valves
almost equally deep, very slightly convex, with a longitudinal sulcus or groove along the
centre of each valve, but usually deeper in the dorsal one ; surface ornamented with from

52 BRITISH DEVONIAN BRACHIOPODA.

twenty-two to twenty-four small, rounded, radiating ribs, of which a few are sometimes
bifurcated, with interspaces of almost equal breadth between them. The two or three
ribs which occupy the median groove are usually smaller than those which ornament the
lateral portions of the valves, the whole being crossed by numerous concentric lines of
srowth. Beak of the ventral valve small, slightly incurved, and with a minute, circular
aperture under its angular extremity ; a small, fiattened space existing, likewise, between
the beak-ridges and the hinge-line. Proportions variable :

Length 6, width 53, depth 13 lines.

Obs. ‘This little shell, characteristic of the Middle Devonian beds of England and of
the Continent, was first discovered at Hope’s Nose, near Torquay, and described by
Phillips as an Orthis. Subsequently, it was found by Professor Schnur in beds of a
similar age at Priim and Gerolstein, in the Eifel, where the shell appears not to be very
uncommon. Professor Schnur, however, gave to the Prussian specimen a new name,
Terebratula dividua, and figured at the same time a portion of the interior, to show two
vertically and spirally coiled lamella, of which the extremities are directed towards the
bottom of the dorsal valve. ‘This species is, therefore, not an Orthis, as was supposed by
Phillips, De Verneuil, and others, nor a Chonetes sarcinulata, as hinted by Professor Morris,
nor a Zerebratula, as supposed by Schnur, but should find place in Dalman’s genus
Atrypa, or Spirigerina of D’Orbigny.

The ‘Atrypa lens of Sowerby (Pl. 21, fig. 3, of Murchison’s ‘Silurian System ’)
belongs to the genus Pentamerus.

The careful examination I have made of the original types now preserved in the
Museum of the Geological Survey, as well as of some others found likewise at Hope's
Nose by Mr. Champernowne, and of a numerous suite of specimens sent to me from the
Hifel by Professor Schnur, leaves no uncertainty in the determination of this iteresting
little species, or of its identity with Zerebratula dividua of the last-named author.

ATRYPA LEPIDA, Goldfuss (sp.). Pl. X, fig. 2.

TEREBRATULA LEPIDA, D’ Archiac and De Verneuil. Description of the Fossils of the Older
Deposits of the Rhenish Provinces, Trans. of the Geol: Soc., 2nd

series, vol. vi, p. 368, pl. xxxv, fig. 2.
_ — A. Roemer. Die Versteinerungen des Harzgebirges, pl. xii, fig. 22,

1843.

SprricERINA — D’Orbigny. Prodrome de Paléontologie Stratigraphique, vol. i, p. 100,
1849.

TEREBRATULA — Schnur,in Dunker und Von Meyer’s Palzeontographica, vol. iii, p. 180,

tab. xxiv, fig. 1, 1853.

Spec. Char. Shell very small, longitudinally oval, or circular; ventral valve ventri-
cose, convex, and deep, with a shallow median groove and three feebly projecting
rounded ribs on each side of the lateral portions of the valve; beak exceedingly small,

ATRYPA. 53

angular; foramen minute, a small flattened space existing between the beak-ridges and
the hinge-line; dorsal valve elliptical and flattened, with a wide, shallow, median depres-
sion, or sinus, extending from the umbone to the front, while a small longitudimal rib
occupies the centre, the sinus being limited on each side by a rounded rib. The surface
of each valve is closely and regularly intersected by numerous squamose concentric lamine.

Length 4, width 4, depth 2 lines.

Oés. I was glad to recognise a specimen of this interesting little species in the
collection of the Rev. J. E. Lee, who had found it in the Middle Devonian Limestone of
Barton, near Torquay, where the shell appears to be rare. It does not appear to have
attained much larger proportions than those above given. Itis stated to be also rather
uncommon in the Hifel, from whence, however, I have obtained about a dozen specimens.
It has been beautifully figured by M. De Verneuil and Professor Schnur. Viscount
D’Archiac and M. De Verneuil have likewise observed that “its form would bring this
species into 4¢/rypa of Dalman, if that genus could be preserved in a scientific classification,
which they think it cannot.” My learned friends were, however, mistaken in this last
supposition, for whether the shells in question be termed Aétrypa or Spirigerina, the genus
is among the best we have in the classification ; and under no circumstance could the shell
be considered a Zerebratula. Although we have never seen the interior dispositions, I
think that the shell must have been provided with spiral appendages similarly disposed
to those figured by Schnur in Afrypa lens.

- A. lepida occurs at Priim, Gerolstein, &., in the Hifel ; and has also been found in the
Hartz.

AtRYPA RETICULARIS, Linneus (sp.). Pl. X, figs. 3, 4.

ANOMIA RETICULARIS, Linneus. Syst. Nat., ed. xii, p. 1132, 1767.

TEREBRATULH PECTINATH, T. SUBTILISSIME STRIATH, T. CANCELLAT&, T, MINUTISSIME
sTRIATH, Schréter. Abhandlungen iiber verschiedene Gegenstande der Natur-
geschichte, pl. iii, figs. 11—18, and pl. iv, figs. 19—26, 1777.

TEREBRATULA PECTINATA, Bruguiére. Hist. Nat. Vers. ; Testacés, Encyclopédie Méthodique,

pl. 242, pl. iv, 1789.

ANOMITES RETICULARIS, Wahlenberg. Nov. Act. Soc. Upsal., vol. viii, figs. 65, 66, 1821.

TEREBRATULA AFFINIS, Sowerby. Main. Con., tab. 324, fig. 2, Jan., 1822.

Sprrirer SowersyI, Def. Dict., vol. 1, p. 295, t. Ixxvi, fig. 2 (valva brachiis spiralibus ornata).

TEREBRATULA (MaGas) cANCELLATA, Hichw., Zool., i, 276, tab. iv, fig. 11.

TEREBRATULITES PRISCUS, Schlotheim. Nachtragen zur Petrefactenkunde, pl. xvii, fig. 2,

1822.
— EXPLANATUS, Schloth. Ibid., pl. xviii, fig. 2.
ATRYPA RETICULARIS, Dalman. Vet. Ac. Handl., pl. iv, fig. 2, 1827; Hisinger, Lethea
Suecica, pl. xxi, fig. 11.
TEREBRATULA PRISCA, Buch. Ueber Terebrateln, p. 71, 1834.

BRITISH DEVONIAN BRACHIOPODA.

ATRYPA AFFINIS, Sowerby, in Murchison’s ‘Silurian System,’ pl. vi, fig. 5, 1839.
Detruyris Prisca, Fahrend., in Bull. Mosc., p. 788, 1844.
TEREBRATULA (ATRYPA) PRISCA, Pfill. Figures and Descriptions of the Palzozoic Fossils
of Cornwall, Devon, and West Somerset, p. 81, pl. xxxiii,
fig. 144, 1841.
a — INSPERATA, Phillips. Ibid., p. 83, pl. xxxiil, fig. 17, 1841.
SPIRIFER AFFINIS, Sow. Trans. Geol. Soc., 2nd series, vol. v, pl. lvii, fig. 11.
TEREBRATULA PRISCA, D’ Archiac and De Verneuil. Trans. Geol. Soc., 2nd series, vol. vi,
p. 392.
_ Prisca, A. Roemer. Die Versteinerungen des Harzgebirges, pl. v, figs. 11—13,
1843.
— RETICULARIS, De Verneuil. Geol. of Russia and the Ural Mount., vol. ii,
pl. x, fig. 12, 1845.
ATRYPA LENTIFORMIS, Vanuzem; and A. AFFINIS, Hall. Geology of the State of New York,
1846.
TEREBRATULA RETICULARIS, Barrande. Ueber die Brachiopoden Silurischen Schichten von
Boehmen, pl. xix, fig. 8, 1847.
— — Bronn. Index Paleontologicus, p. 1248, 1848.
SPIRIFERINA — D’ Orbigny. Prodrome, vol. i, p. 99, 1849.
TEREBRATULA PRISCA, Quenstedt. Handbuch der Petrefactenkunde, p. 461, tab. xxxvii,
figs. 1—4, 1851.
ATRYPA RETICULARIS, Davidson. British Fossil Brachiopoda, Introduction, vol. i, pl- vii,
figs. 87 —93, 1853.

TEREBRATULA INSQUAMOSA, Schnur. Dunker und Meyer’s Palzeontographica, vol. iii, p. 181,

fig. 4, 1853. 2
ATRYPA RETICULARIS, Morris. A Catalogue of British Fossils, p. 132, 1854.
ANOMIA —_ Sharpe, in Hanley’s ‘Ipsa Linnea Conchylia,’ p. 127, 1855.
SPIRIGERINA — M‘Coy. British Paleozoic Fossils, p. 379, 1852.

— _— Sandberger, Die Brachiopoden des Rheinischen Schichtensystems
in Nassau, p. 51, pl. xxxiii, fig. 1, 1851.

ATRYPA — Woodward. A Manual of the Mollusca, p. 228, figs. 144, 145, and
pl. xv, fig. 21, 1856.

— — J. Hall. Report on the Geological Survey of the State of Iowa, pl. vi,
figs. 4 and 5, 1858.

ah — Hall. Natural Hist. of New York, Paleontology, vol. iii, p. 253,
pl. xlii, fig. 1, 1862.

(Many more references could be added, but the list above given contains the most
important.)

Spec. Char. Shell oblong ovate, widest near the hinge ; beak small, acute, very little

produced, incurved, and often pressed to the umbone of the ventral valve, so that the small
circular foramen, situated under its incurved extremity, is rarely perceptible. Dorsal valve
uniformly convex, at times gibbous, and without any defined fold, but becoming slightly
concave towards the cardinal extremity or on either side of the umbone. Ventral valve much
less convex and deep than the opposite one, convex at the beak and along the middle, but
becoming gently concave towards the lateral portions or margins of the valve; front margin a

PP oem

ATRYPA. 55

little advanced, indenting that of the dorsalone. Surface of valves ornamented with nume-
rous small, radiating, rounded ribs, which continually augment towards the margin by the
means of bifurcation, or by the intercalation of ribs at various distances from the beaks.
The surface is also closely intersected or crossed by numerous foliacous expansions, in
the shape of plaited laminz or frills. Shell-structure fibrous and impunctate. Spiral
appendages, originating at the base of the socket-walls, form two large hollow cones
placed horizontally, with their apices directed inwards and towards the hollow of the
same (dorsal) valve, which they almost fill; the inner sides of the spires are pressed toge-
ther and flattened, and with their terminations close to each other near the centre of the
bottom of the shell (Pl. xi., figs. 7, 8). In the interior of the dorsal valve the quadruple
impressions of the adductor muscle are separated by a medio-longitudinal ridge, the
pedicle or dorsal adjustor muscles being probably fixed to the two small cardinal plates.
In the ventral valve, at the base of the teeth a semicircular ridge curves on each side,
forming a saucer-shaped depression, open in front, and into which the muscles were
fixed (Pl. x1., fig. 9); the divaricator muscles seem to occupy the largest portion of the
depression, and to have been divided by an obscure mesial ridge ; beyond these, and at
a little higher up, are placed the pedicle muscular impressions, and above the mesial
ridge, nearer the beak, is seen the oval scar Jeft by the adductor. The vascular impres-
sions on the dorsal valve consist of two principal trunks, originating on each side
between the cardinal and pedicle muscles ; these soon divide into two primary branches,
which extend right and left almost parallel to the margin, giving off at various intervals
smaller bifurcating veins, which are directed towards the edge of the shell. Proportions
very variable :

Length 2 inches 5 Jines, width 2 inches 2 lines, depth ] inch 2 lines; but the shell
has usually smaller dimensions.

Oés. At page 127 of Hanley’s ‘Ipsa Linnzea Conchylia’ we find the following re-
marks :—‘* Anomia reticularis. In the Linnean collection are several specimens of this
fossil, which alone of those present—and its presence in his cabinet has been recorded by
our author—answers to the description in the ‘Systema.’ The species, which is well
known, and is found very abundantly in all the beds from the Devonian to nearly the
bottom of the Silurian system, has received the following appellations :

“ AnomirEs RETICULARIS, Wahlenberg, ‘ Nov. Act. Soc. Upsal.,’ vol. vii, p. 65.

“'TEREBRATULITES PRISCUS, Schlotheim, ‘ Petrefact.,’ pl. Ixxxvil, fig. 9.

“'TBREBRATULA AFFINIS, Sowerby, ‘ Min. Conc.,’ pl. 324, fig. 2.

* &ex &e.

“The name of reticularis, being traced back to Linnzeus, must henceforth be adopted
to the exclusion of the many others it has received. (Sharpe, MS.)”

In this statement I am fully prepared to coincide, having also carefully studied the
Linnean specimens in company with MM. Bouchard and Salter.

It is a most variable shell, and has, consequently, been shifted about from genus to.

56 BRITISH DEVONIAN BRACHIOPODA.

genus, and has received a great number of different specific denominations. In 1777,
several of its varieties were well figured by Schréter, and who, while describing them,
did apply to each modification in shape distinctive denominations, such as pectinata,
subtilissime striata, cancellata, minutissime striata, &c. ‘The width and number of the
striae, as well as of the concentric laminz, constitute the principal differences observable
in specimens of this important and curious species. All these modifications can be
traced in specimens from any single locality, as is the case at Ferques, in the Boulonnais,
France, as well as at Reffrath, near Cologne, in Prussia, where the shell is exceédingly
abundant. The beak is usually so closely-pressed to the umbone of the dorsal valve,
that no foraminal aperture can be perceived; and this led Dalman, the founder of the
genus Atrypa, to suppose that the beak was czmperforate. In some examples, however,
of A. reticularis the foramen can be perceived: consequently Dalman’s term becomes
a zoological misnomer, and D’Orbigny’s Spirigerina would be a preferable substitute.
The identity of the Silurian and Devonian specimens have likewise been recognised by
‘ several distinguished observers. ‘Thus, at page 297 of the second edition of Murchison’s
‘ Siluria,’ we find—‘ Among the Mollusca nearly all the, species of Atrypa, Orthis, and
Spirifer, differ from those of the Silurian era. One shell, however, the Atrypa reticularis,
must be mentioned as an exception to the prevalent rule of each great group being
distinguished by peculiar forms ; for this hardy species, with which the reader became so
familiar in the Silurian rocks, lived on to the Devonian era, and is as common in the
limestones and shale of Devonshire as in the older series. It even ranges to the
furthest known geographical limits of the Devonian rocks, to Armenia, the Caucasus,
and China on the east, and to the Devonian deposits of America on the west!” And
again, at page 379 of the work on ‘ British Paleozoic Fossils, Professor M‘Coy observes,
while treating of Spirigerina reticularis, that he cannot perceive the slightest difference
between some of the Eifel and Upper Silurian and some of our Devonshire specimens.

Atrypa reticularis occurs abundantly in the Middle Devonian Limestones of Barton,
Lummaton, and Hope’s Nose, near Torquay. In limestone of a similar age at Dartington
and Black Hall, near Totness ; near Plymouth ; at Woolborough and Ogwell, near Newton
Abbot ; Chircombe Bridge, near West Ogwell; and Hagginton Hill, near Ilfracombe, &c.,
in Devonshire. In Cornwall it occurs at Looe; and, according to Mr. Salter, in the
Upper Devonian beds of Petherwin and Landlabe (?).

On the Continent it abounds at Ferques, Chimay, Couvin, Hay; in the Eifel; at
Paffrath, Refrath, Lustheide, Hibigenstein (Hartz), Lake Ilmen, Volkof, Voronege, &c. ;
also in the Ural, Smeimogorsk (Altai); State of Ohio, New York, Tenessee, &c., &c.

Some modifications (?) of this species may be worthy of varietal denominations.

Fic.

PLATE I.

DEVONIAN SPECIES.

1—8. ? Terebratula Sacculus, Martin, varr. Several modifications in shape. From the

18.

19, 20.

21.

Middle Devonian Limestone of Barton
and Lummaton, near Torquay, Devon.
elongata, Sch].? Upper Devonian? Brown grits of East Hill,
Braunton, Devonshire.
juvenis, Sow. Different specimens from the Middle Devonian
“Limestone of Barton and Lummaton. Fig. 13,
Sowerby’s type; Plymouth. Mus. Geol. Soc.
* Newtontensis, Dav. Middle Devonian, Woolborough Quarry, near
Newton Abbot, Fig. 16, Collection of Mr.
Champernowne. Fig. 17, Mr. Vicary’s Col-
lection.
Stringocephalus Burtini. Def. Middle Devonian, Bradley, near Newton. Maus,
Geol. Soc.

= Terebratula porrecta, Sow. After the original
figures, Min. Conch., tab. 576, fig. 1. Bradley,
near Newton.

A circular, and unusual shape ; Chircombe Bridge,
Devonshire. Mus. of Geol. Survey. A similar
specimen is represented in p. 294, fig. 4, of the
second edition of ‘Siluria,? but there named

29

2? 33 3)

29 9) bP]

St. giganteus.

= St. giganteus, Sow. A large distorted example,
from the Middle Devonian Limestone, near
Plymouth, and of which a reduced figure is
given by Sowerby in the ‘Trans. Geol. Soc.,’
vol. v, 2d series, pl. lvi, fig. 11.

3”? 39 3)

DEVONIAN,

sade
eae

Tho® Davids del & lith WWest imp

anes cian : .
i

pe) ee :

- atres oi. Le , >

fer cibee
; Bath yen ats
Bir

tr

HAND

as: .

10,44,

3)

PLATE II.

DEVONIAN SPECIES.

Stringocephalus Burtini, Def. Young shells. Middle Devonian, Bradley, near

Newton. Museum of the Geological Society.

From Woolborough Quarry, near Newton Abbot. Col-
lection of Mr. Walton.

= St. giganteus, Sow. After Phillips’ ‘Pal. Foss. of
Cornwall, Devon, and West Somerset,’ pl. xxxii, ~
_ fig. 142.

= St. giganteus. A very large, distorted, flattened
specimen. From near Plymouth. Mus. Geol.
Soe. :

= Uneites levis, M‘Coy. After M‘Coy, ‘ British Pal.
Fossils,’ pl. 24, fig. 6. From near Newton.
Cambridge Museum.

Specimens showing the internal dispositions of the

loop, &c.; reduced figures after the originals .
by Prof. E. Suess.

Pl Il

DEVONIAN

Tho® Damidson del.& lith.

SrAlOr

Vg.

13, 14,

15.

16.

Ww bo
c=

PLATE III.

DEVONIAN SPECIES.

Athyris ? — Atrypa oblonga, Sow., ‘Trans. Geol. Soc.,’ 2nd series, vol. v, tab. xxxvi, fig. 6,
Upper Devonian?, Barnstaple. Mus. Geol. Soc. Stated by Professor M‘Coy
to be a crushed internal cast of Athyris concentrica.

Merista plebeia, Sow. sp. = Sp. scalprum, Roemer. Fig. 2, from Sowerby’s type, Mount Wise,
near Plymouth. Mus. Geol. Soc. Fig. 4 from north side of Stone
House Hill, near Plymouth. Plymouth Inst. Mus. Figs. 3, 5, 6,
7 from near Newton Abbot and Torquay ; fig. 5 shows the peculiar
fissure produced by a portion of the matrix having dropped out where
the “‘shoe-lifter-shaped process’ existed.

= dtrypa lacryma, Sow., ‘Geol. Trans.,’ 2nd series, vol. v, tab. xxxvi,
fig.9. These drawings are made from Sowerby’s original specimens,
in the Mus. Geol. Soc., from the Middle Devonian Limestone of
Stone House Hill, near Plymouth.

Athyris concentrica, var. Fig. 11, Upper Devonian, East Petherwin, Cornwall. Fig. 12, from

Hope’s Nose, near Torquay. Collection of Mr. Pengelly.
Von Buch. Typical shape, from the shale at Mudstone Bay, South of Berry
Head, Devonshire. Collection of Mr. Pengelly.
Internal cast, showing the muscular impressions, from the Upper Devonian,
Pilton Beds, Orchard Quarry, 1 mile north of Barum, North Devon.
Collection of Mr. J. M. Hall.

re eit ees = Atrypa indentata, Sow., ‘ Geol. Trans.,’ 2nd series, vol. v, pl. liv, fig. 6.
Petherwin, Cornwall. After the original figure.
33 te skoad = Atrypa decussata, Sow., ‘Trans. Geol. Soc.,’ 2nd series, vol. v, pl. liv,
fig. 5. Petherwin. After the original figure.
ue Le ae Perhaps the same as A. decussata, near Newton Abbot. Collection of Mr.
Vicary.

Athyris phalena, Phillips. The original specimens from shale at Hope’s Nose, near Torquay.
Mus. Geol. Survey.

= A. hirundo, Phillips, From the original example, Hope’s Nose, near
Torquay. Mus. Geol. Survey.

Athyris Newtoniensis, Dav. Middle Devonian, Woolborough Quarry, near Newton Abbot.

Collection of Mr, Champernowne.
» Bartoniensis, Dav. Barton, near Torquay. Collection of Mr. Lee.
concentrica ? = A. hispida, Sow., ‘Trans. Geol. Soc.,’ vol. v, 2nd series, pl. liv, fig. 4,
Petherwin, Cornwall.

3) ”

bE)

bi na

a

nidson del.% h

AL

DEVONIAN

W West imo

we

4 hs

ay A * thin eo ve
v8 nw. te weasel iD, j

i

Fic.
1—3.
4,
3I—7.
8—10.
Vi, Wz.
le.

14, 15.
16.
17—22.
28; 2A.
25—28.
29—32
33:

34; 4%

PLATE IV.
DEVONIAN SPECIES.

Athyris, sp.? Supposed to belong to 4. concentrica. Casts and impressions from brown grit,
Upper Devonian of Incledon, near Barnstaple and Braunton.
2 ? Internal cast of an undetermined species, from the light brown grits, Looe,
Cornwall. Collection of Mr. Pengelly.
Rensseleria stringiceps’? F. Roemer. Casts, Devonian Limestone, Hagginton Hill. Collection
of Mr. Valpy.
Retzia ferita, Von Buch. Fig. 8, Woolborough Quarry, near Newton Abbot. British Museum.
Fig. 9, Barton, near Torquay. Collection of Mr. Lee. Fig. 10,
Mus. of the Geol. Survey.
Uneites gryphus, Defr. From the Dartington dolomitic limestone, near Totness, and Middle
Devonian Limestone, Woolborough Quarry, near Newton Abbot.
Spirvifera lineata? Martin. Middle Devonian, Woolborough Quarry, near Newton Abbot. Col-
lection of Mr. Pengelly.
after Phillips, ‘ Pal. Foss. of Cornwali, Devon, and West Somerset,’ t. xxviii,
fig. 120, Upper Devonian, Petherwin and Landlake. [Never having seen
these specimens, I am unable to affirm their identity with the Carboniferous
Sp. lineata.]
ie A == Sp. microgemma, Phil., ‘Pal. Foss.,’ pl. xxvii, fig. 116, Not having seen
this specimen, I here introduce it upon Professor Phillips’ authority.
Hope’s Nose, near Torquay.
Spirifera nuda, Sow. Middle Devonian. Fig. 17, Barton, near Torquay. Sharpe Collection,
Mus. Geol. Soc. Fig. 18, original type, Dockyard, near Plymouth.
Mus. Geol. Soc. Figs. 19, 20, Woolborough, near Newton Abbot.
Fig. 21, Dartington, near Totness, Devon. Collection of Mr.
Champernowne. Fig. 22, Barton. Collection of Mr. Lee.

” ,

~

cs », =WSp. pulchellus, Sow., ‘Trans. Geol. Soc.,’ vol. v, 2nd ser., tab. lvii, fig. 9,
Middle Devonian Limestone, Mount Wise, near Plymouth. Mus. Geol.
Soe.

55 Urii, Flem. = Sp. unguiculus, J. Sow., in brown grits, Upper Devonian of Bradford,

near Barum, North Devon; and South Petherwin, Cornwall.
Fig. 26, original figure in ‘ Geol. Trans.,’ 2nd series, vol. y,
pl. liv, fig. 8.

5; eurvata, Schloth. Decorticated examples. Fig. 29, Barton, near Torquay. Sharpe’s
collection, Mus. Geol. Soc. Fig. 30, Lummaton, near Tor-
quay. Fig. 31, Chircombe Bridge, near Newton. Collection
of Mr. Vicary. Fig. 32, near Torquay. (See more perfect
examples, pl. ix, figs. 22, 26, & 27.)

ob) », - Internal flattened cast, Devonian, Looe, Cornwall.

% » ? Woolborough Quarry, near Newton. Collection of Mr. Pengelly.

de ANS

VONIAN

Dae

ith

hos Davidson, del ¢

TT)

Ag

eentitoy ol}. Woe
pe ewilli deulions tuo. A

ted }
ih)

ot
/

Fic.

cw

9)

PLATE V.

DEVONIAN SPECIES.

Spirifera disjuncta, Sow. = Sp. Verneuiliit, Murch. After the original illustra-

>>

tion, ‘ Trans. Geol. Soc.,’ 2nd ser., vol. v, pl. liv, fig. 13.
Upper Devonian, Petherwin, Cornwall.

Ibid., vol. v. pl. lin, fig. 8. This internal cast shows the
muscular impressions. Barnstaple.

From South Petherwin. Correctly restored, from exact
measurements.

Middle Devonian, Woolborough Quarry, near Newton
Abbot. Fig. 4, Collection of Mr. Champernowne ; fig.
5, Mr. Lee’s Collection ; fig. 6, Geol. Survey Coll.

Brown grits, Barnstaple.

= Spirifera gigantea, Sow. Flattened and distorted, in
micaceous Devonian slate, at Tintagel, Cornwall. Sowerby
mentions that some examples measured nearly nine
inches across.

= Sp. calcarata, Sow. After the original illustration,
‘Trans. Geol. Soc.,’ 2nd series, vol. v, pl. liu, fig. 7.
Barnstaple.

Brown grits, Upper Devonian, Croyde Bay, seven miles
north-north-west of Barum. Coll. of M. M. Hall.

= Sp. eatensa, Sow. Distorted specimen. From South
Petherwin, Cornwall. Mus. Geol. Soc.

= Spirifer protensus, Phillips. The original illustration, ‘ Pal.
Foss. of Devon, Cornwall, and West Somerset,’ pl. xxviii.
South Petherwin. Mus. Geol. Survey. This is a de-
corticated, injured specimen, or cast; but as remains of
the striation occur on several portions of the ventral
valve, I have been able to give a correct restored illus-
tration in fig. 12%.

Teal Wi

DEVONIAN

BES SR si weir

ison del eb Irth

Vhos Dawic

L

oy | a

Fic.
1—4.

ot

6, 7.

10.

PLATE VI.

DEVONIAN SPECIES.

Spirifera disjuncta, var. Barumensis,Sow. Fig. 1, a correctly restored measured

2?

representation, taken from two specimens in the brown
grits, Upper Devonian, of Braunton. Fig. 2, a fragment
from the Pilton beds, Croyde Bay. Fig. 3, from
Braunton, Fig. 4 is taken from a gutta-percha cast,
made from an impression of the shell left in the brown
grit of Braunton. The area is unusually largely
developed.

og = (Sp. distans, Phillips, not of Sow., ‘ Paleozoic Fossils of
Cornwall, Devon, and West Somerset,’ tab, xxix,
fig. 127). Devonian, near Newton. Collection of

Mr. Lee.

we = Sp. grandeva, Phillips. After the original representation,
pl. xxx, fig. 131. Upper Devonian, South Petherwin,
Cornwall.

3 = Sp. mesomala, Phillips. Pl. xxxi, fig. 137. Brushford,
North Devon. This is the original figure, but to me
undeterminable.

aperturata, Schl.? After Phillips, pl. xxx, fig. 133. Linton, North
Devon. This fragment will not admit of a certain
identification.
obliterata, Phil. After Phillips, pl. xxxi, fig. 135. Brushford,
North Devon.

11—15. Spiriferina cristata, var. octoplicata. Figs. 11, 12, 13, casts in the Devonian

16,217.
18—21.

yellow grits of Looe, Cornwall. Figs. 14, 15, from
the dolomite, Dartington, near ‘lotness, Devon.
Coll. of Mr. Champernowne. Found in the same
beds with Uncites gryphus.

3 insculpta?, Phillips. Middle Devonian, Lummaton, near Torquay.

sere simplex, Phil. Barton, Lummaton, and Woolborough. Collections

-of the Geol. Survey, Mr. Pengelly, and Mr. Vicary.

PL VI

semen
Ase ee

W.West imp

del. et lith

ThoS Dayidson

tie Liston aig Fe

: eo on 7 ‘
: 059 > Pave ie: i

- es - ae
, 7 = ‘< ban ; h

=

Fie:
t.,
2—10.
11—14.

PLATE VII.

DEVONIAN SPECIES.

Spirifera undifera, ¥. Roemer. ‘Typical shape. Middle Devonian Lime-
stone, near Newton Abbot.. British Museum.

Several variations in shape. Fig. 2 preserves its con-
centric lines or sculpture. Figs. 2, 6, 7, 8, Wool-
borough (decorticated examples). Figs. 3—5 from
Barton, near Torquay. Collecticn of Mr. Lee. Fig. 4,
Mus. Geol. Survey. Fig. 10, Sp. pinguis ?, Phillips,
‘Pal. Foss. of Cornwall, Devon, &c.,’ pl. xxxi, fig. 139.
Barton, near Torquay. Collection of Mr. Lee.

>? 2?

>? svar. undulata, ¥. Roemer. Several variations in shape,
Woolborough Quarry. Collections of Messrs. Pengelly,
Lee, and Vicary.

> 2?

DEVONIAN. PL. VIL

Tan* Davidson del. et lith

inet

PLATE VIII.
DEVONIAN SPECIES.

1—3. Spirifera cultrijugata?, F, Roemer. Internal casts and impressions. Lower
Devonian ?, Looe, Cornwall. Collection of Mr.
Pengelly.

A, 5. . levicosta, Val. in Lamarck, = Sp. ostiolatus, Schl. Fig. 4, partly re-
stored specimen, from Middle Devonian, Woolborough,
near Newton Abbot. Fig. 5, from an imperfect speci-
men likewise, figured by Phillips (‘ Pal. Foss. of
Cornwall, Devon, &c.,’ pl. xxv, fig. 132°); Valley
of Rocks, Linton, Devonshire.

6—8. 5 speciosa, Schlotheim. Hope’s Nose, near Torquay. Fig. 6, Col-
lection of Mr. Pengelly. Fig. 7, Mus. Geol. Survey.
Fig. 8, Mus. Geol. Soc.

9; 20. g »? =Sp. costatus, Sow. Fig. 9, after the original figure (“T'rans.
Geol. Soc.,’ 2nd ser., vol. v, tab. lv, fig. 6); Fowey,
Cornwall. Fig. 10, Sp. costatus, Phill. (‘ Pal. Foss.,’
pl. xxx, fig. 134°); Meadfoot Sand, near Torquay,
Devon. Are these referable to Sp. paradova? The
specimens are so imperfect as to be hardly determinable.

GES. pe »? =p. paradoxus, Schl. Fig 11, Hope’s Nose, near Tor-
quay. Fig. 13, Fowey, Cornwall. Mus. Geol. Survey.
12. , (uncertain) It has been referred by the Survey Palzontologists to Sp.

Bouchard ; but the width of the area negatives such
a conclusion.

14, 15. 5 sub-cuspidata, Schnur. Hope’s Nose, near ‘l'orquay. Collection of
Mr. Pengelly.
liye 17: _ hysterica, Schloth.? From Linton, North Devon. Sharpe’s Col-

lection, Mus. Geol. Soc.
18. i »? Middle Devonian Limestone, near Plymouth.

ee ee ee

DEVONIAN. PI. VIL

Tho* Davidson del g

Fic.
1—10.
11—14.
15—17.
18—20.
21.
22.
20%
24, 25.
26, 27.

PLATE IX.
DEVONIAN SPECIES.

Cyrtina heteroclita, Def. All the figures, with the exception of fig. 2, from
Middle Devonian, Barton and Lummaton. Fig. 2,
from Woolborough. Fig. 4, Sp. subconica, var., Sow.,
not Martin. Collections of Messrs. Lee, Pengelly, &c.,
Fig. 9, interior of the ventral valve, enlarged. Fig. —
10, longitudinal section of the shell.

‘ ay var. Sp. cuspidatus, Phillips, not Martin (‘ Pal. Foss.,
t. xxix, fig. 124). Barton and Lummaton, near Tor-
quay. Collections of Messrs. Lee and Sharpe, &c.

,, Demarlii, Bouchard. Barton, near Torquay. Collection of Mr. Lee.

,, ? amblygona, Phill. Fig. 18, Ter. amblygona, Phill., from the original
example, Barton. Collection of Mr. Lee. Figs. 19
and 20 from Barton and Lummaton, near Torquay.

Spirifera Newtoniensis, n. sp. Woolborough. British Museum.

2 curvata, Schloth., var. of Sp. curvatus? Woolborough Quarry.

Collection of Mr. Champernowne.
» megaloba?, Phill. After Phill., ‘Pal. Foss. of Devon,’ &., pl. xxxi,
fig. 140. Brushford. Undeterminable fragment.

» rudis?, Phill. After Phill., ‘ Pal. Foss.,’ tab. xxxi, fig. 186. Baggy
Point. Undeterminable fragments.

, eurvata, Schloth. Fig. 26, Middle Devonian, Dartington, near
Totness. Fig. 27, Hope’s Nose. Collection of Mr.
Champernowne. 7

DEVONIAN. a

PRUL a

he? Davidsen dale Ei

a

PALBONTOGRAPHICAL SOCIETY.

INSTITUTED MDCCCXLVIT.

LONDON :

sa

A MONOGRAPH

OF

THE EOCENE MOLLUSCA,

OR,

DESCRIPTIONS OF SHELLS

FROM

THE OLDER TERTIARIES OF ENGLAND.

BY

SEARLES V. WOOD, F.G:S.

PART II.

BIVALVES.

LONDON:
PRINTED FOR THE PALHZONTOGRAPHICAL SOCIETY.
1864.

day

J. E, ADLARD, PRINTER, BARTHOLOMEW CLOSE,

BIVALVIA. 75

21. Mopioua Barronensis, S. Wood. Tab. XIX, fig. 18.

A small specimen of a Modiola, of which the figure above referred to is a repre-
sentation, has very recently come into Mr. Edwards’s possession. It is not in a state of
preservation sufficient for full and fair description, and I have proposed the above name
provisionally. It appears to be covered entirely with large rays or costule; it is more
elongated than the fragment figured at fig. 5, Tab. X, and it has not the diversified rays
which ornament that shell.

22. Moprona (?) crassistriaTa, Hdwards, MS. Tab. XIX, fig. 16.

Spec. Char. M. testé parvd, ovato-trigonuld, tenui, siphoni-regione depressiusculd,
radiatim costellaté aut crassistriatd ; costellis vel striis rotundatis, dichotomis ; umbonibus
minimis, subterminalibus ; margine cardinali subrecto.

Shell small, ovately triangular, thin; siphonal region somewhat depressed, covered
with thick radiations or riblets, rounded and bifurcating ; beaks small, nearly terminal ;
dorsal area straight.

Length, + an inch.

Locality. Bracklesham (Hdwards).

The specimen above described has recently been added to the cabinet of Mr.
Edwards, and I have considered it, as Mr. Edwards has done, a distinct species. It
differs from both of the previously described coarsely striated species, flabellula and
nodulifera, being much shorter than the former, with the strie or riblets somewhat finer ;
and from the latter, with which it agrees in form, it differs in not having the nodules of
that species. Our present specimen is a pretty shell, and the rays with which it is
ornamented are rounded, the spaces between them rather narrow, or at least they are less
so than the rays themselves. ‘The specimen adheres too closely to the matrix to permit of
a removal, and the interior is entirely hidden. It bears some resemblance to M. pectinata,
Lam. (Desh., ‘ Coq. foss. des Env. de Par.,’ t. 1, p. 259, pl. 39, figs. 6—8), but our shell
is shorter, more angulated, with a comparatively longer dorsal area, and the striz are
coarser.

The umbo in this is nearly terminal, with a very trifling projection of the pedal
region ; there is an uncertainty as to its correct admission into Modiola. .

11

76 EOCENE MOLLUSCA.

Moproia DesHayEsIAna? J. Sowerby. Tab. XIX, fig. 19.

A shell from Mr. Edwards’s cabinet here represented is referred with doubt to the
Bracklesham species. The figure 14 of Tab. XIII was copied from Mr. Dixon’s work,
and a comparison could not be instituted. I have therefore thought it desirable to
represent the present specimen, as it presents a difference in outline, and may possibly
belong to another species; at least it constitutes a variety, which I will call Hemp-
steadiensis.

The form of our fossil is more pointed in the siphonal region than the figure of the
Bracklesham or the Paris Basin specimens; it is less regularly cylindrical, and not so
elongated, and there is a considerable slope from the extremity of the hinge-line to the
siphonilateral margin. Several casts of specimens have been found, and there is on one
individual a portion of the shell remaining which is very smooth and glossy, and with a
magnifier the fine and faint cross or radiating strize may be seen. The animal appears
to have formed for itself a thickened lining to the crypt in which it dwelt. The only
locality at present known is Hempstead, where it is found embedded in the shell of an
oyster.

In the ‘ Quarterly Journal of the Geol. Soc.’ for November, 1862, p. 330, is a paper
by Dr. Sandberger, in which he speaks of a fossil from Hempstead as identical with Mod.
delicatula, Desh. This British fossil was received by him from Mr. Edwards, and is the
same species as the one I have had figured, but I cannot coincide in Dr. Sandberger’s
opinion. The following differences appear to me to be sufficient to keep the English and
the French shells specifically distinct. The umbo is more terminal, the ventral margin
less convex, the dorsal or hinge area shorter, and the siphonal region is more oblique and
pointed in our shell than in JW. delicatula. My comparison is dependent upon the
characters given by M. Deshayes; but judging from the figure and description by that
accurate and able naturalist, I think the two forms cannot be specifically united.

23. Mopioua (?) consoprina, S. Wood. Tab. XIX, fig. 17,

Length, 2 inches.

Locality. Alum Bay (Fisher).
One specimen is all that I have yet seen, and that unfortunately is not in a condition

for fair determination. It was found, Mr. Fisher tells me, in the Bracklesham bed at
Alum Bay; the specimen is firmly imbedded in the matrix (a sandy marl), by which the
interior is hidden, and the umbonal region is not quite perfect. It differs from J/. sud-
cancellata principally in having fewer and coarser rays, and it has not the concentric ridges
or distinct lines of growth subcancellating the exterior of that species. The figure has

BIVALVIA. ri

been a little too much improved at the umbo, and it is difficult in its present condition
to say whether it belongs to Mytilus or Modiola. Its present name is merely
provisional.

16*. Mopioxa suscarinata? Lamarck. Tab. XIX, fig. 20.

At page 71, Tab. XII, fig. 9, is figured and described a shell from the London Clay
at Highgate, and referred with doubt to Lamarck’s species from the Paris Basin.
Mr. Edwards has since obtained a specimen from Barton, with the general characters
of the French species, although differing in some minor particulars, and I have thought it
desirable that it should be represented. In comparing our present specimen with the
figure of the Paris Basin species, there appears a difference in the length of the hinge-area,
and also in the direction of the margins, both the dorsal and ventral margins being more
curved in the French shell than im our own; there is also a slight difference between
the Barton specimen and the one previously figured from Highgate, which has a more
prominent or subcarina] projection, with the umbo rather more terminal.

Our shell is covered with elevated or rather imbricated lines of growth, and these are
more distant upon the siphonal region than upon the other parts of the shell; they appear
as if they once supported a fringed epidermis like that which ornaments the shell which
has been called J. darbata.

Since the above was written and the figures engraved, I have seen a specimen in the
cabinet of Mr. Prestwich of the following dimensions :—3} inches in length, with a height
or breadth of 1 in., and a tumidity of an inch and half: this was obtained at Clarendon
Hill, near Salisbury, and I presume it to be the same as M. subcarinata from Highgate.

24. Mopiota suBcANcELLATA, Ldwards, MS. Tab. XIX, fig. 15.

Locality. Barton (Hdwards).

An imperfect specimen has recently come into the possession of Mr. Edwards, to
which is attached the above specific name. It bears considerable resemblance to two
species from the Paris Basin, viz., Mod. Rigaultii, Desh. (‘ An. sans vert. du Bass. de Paris,
t. 1, p. 29, pl. 74, figs. 23, 24), and Mod. Levesquei (id., p. 30, pl. 75, figs. 4, 5); our
shell appears to approach rather nearer to the latter, and, if the specimens themselves
could be compared, might possibly be referred to that species; there are, however, some
differences which may be here pointed out. The Barton shell does not appear to have
been so broad or so high as that of the French species, neither has it so long an area for
connexus ; the dorsal edge is finely but deeply denticulated, as that of J. Levesque is
also represented to be, but it does not appear so much curved as in the latter. There

78 EOCENE MOLLUSCA.

are two rather unequal and not very perfect teeth immediately beneath the umbo, within
which is also the impression of the oral adductor; the external radiations are numerous
and flat, and they bifurcate at an early age; the interspaces are ornamented with raised
lines of growth, which impart to them an irregularly cancellated appearance, and these, if
they exist, are not represented in the French shell. In the young state, the form
resembles more the normal state of JModiola, which it seems to have nearly lost in the
adult, where the umbo has become more pointed, like that of Mytilus.

ARCA. JLinneus.

Generic Character. Shell inequilateral, generally equivalved, more or less quadrate
or trapezoidal; ventral margin sometimes closed, at others open or sinuated; externally
covered with radiating striz ; umbones distant, with more or less open area for connexus ;
hinge straight, with many teeth; palleal impression entire.

This is almost exclusively a marine genus, and comprehends nearly five hundred species.
Some of these, however, vary so materially in the form, number, and arrangement of the
denticles upon the straight and elongated margin of the hinge, as to have been separated
into several genera or sections, in accordance with those variations. The generality of
species show an opening more or less in the ventral margin, indicating a habit in the
genus to spin a byssus.

In some few species there is an inequality in the valves; when this is the case, the left
one is the larger of the two, and this inequality is found principally in those species
which are without a sinuated margin. |

The hinge, or dental area, is quite straight; this in some species is furnished with nu-
merous small teeth placed at right angles to the line of it; in others, the denticles are few in
number and are variously inclined, until they become at the extremities parallel with the
hinge-margin, exhibiting every possible degree of intermediate variation. ‘I'he shells that
have been generally included in this genus from the older rocks have most of them very
oblique denticles, like those of Cucullea, but they are not restricted to that form of dentition.
The area between the umbo and the dental margin over which the connector is spread is
at times very large and open; the diverging and chevron-formed lines which ornament
this space are deeply impressed in the shell; into them a portion of the ligament has
been inserted for strength and protection, as also to have an intervening raised portion
on which to act as a fulcrum. There is in this character an approach to Limopsis,
in which there is an angular depression; but it has not any analogy with the bipartite or
amphidesmous form of connexus, inasmuch as the action of the whole connector is liga-
mental, acting by contraction and elongation. In Pectunculus the area is marked with a
single divergence, forming an obtuse angle; but in the present genus, in which some of

BIVALVIA. 79

the more inequilateral species have a large, open, and elongated space for connexus, the
linear portion diverges from the umbo at an acute angle; and thus a greater strength is
given to these lines than if they were spread over the entire surface. If the same mode of
divergence existed in the siphonal region of these shells, the linear portions of the ligament
would be extended at an angle so obtuse, that they would be almost useless for a ligature,
and therefore another set of divergent lines is formed on this part of the dorsal area, by
which a greater tenacity is obtained and the firmer union of the two valves is secured.

1. Arca apprnpicuLaTa, J. Sowerby. ‘Tab. XIV, fig. 3, a—c.

ARCA APPENDICULATA. J. Sow., Min. Conch., t. 276, fig. 3, 1820.
— pvupticata. J. Sow. Min. Conch., t. 474, fig. 1, 1824.
= — Morris. Catal. Brit. Foss., p. 185, 1854.
— uactEa. Solander, in Brand. Foss. Hant., t. 8, fig. 106, 1766.
— sutcicosta. Nyst. Coq. foss. Belg. p. 257, pl. 18, fig. 9, a, 6, 1843.

Spec. Char. A. testé elongata, subtrapezoidali, gibbosuld, inequilaterah, equivalvi,
radiatim striata vel costulaté, concentricé decussatd ; costulis duplicatis vel bifurcatis ;
siphoni-regione longiore, oblique truncata; pedi-regione superné angulatd, inferné rotun-
data ; umbonibus subprominentibus, tncurvis ; ared connexiis magna, partim ornatd.

Shell elongate, irregularly trapezoidal, tumid, inequilateral, equivalve, radiated with
prominent lines or riblets, decussated by lines of growth; pedilateral margin angular
above and rounded below ; siphonal region angulated; beaks rather prominent, with a
large area for the connector, partly lineated.

Length, 13 inch ; height, sths of an inch.

Localities. Barton.

Belgium, Viiermael, Hoesselt, and Lethen (WVyst.).

This species is in England restricted to the above locality, where it is not very
rare; and as I believe the four names above mentioned belong to one and the same species,
I have adopted appendiculata as being the older of the four. The peculiar appearance
which suggested the name appears to be a plain and naked space on the pedal side of the
area for connexus, which is free from any diverging impressed lines, while they are distinct
on the siphonal side ; at least I presume this to be so; I am quite unable to see anything
like appendages to this part of the shell. The exterior of the valve’ is ornamented with
radiating stri or riblets, and these generally duplicate, sometimes triplicate, on the outer
or older portion of the shell ; the lines of growth are prominent, decussating the interspaces
as well as the rays, which, in consequence, become somewhat nodulous, particularly over
the pedal region; the dental area is furnished with teeth along the entire length; they
are at nearly right angles to the hinge-line, but incline as they recede from the centre,

80 EOCENE MOLLUSCA.

2, Arca avicuLina? Deshayes. Tab. XV, fig. 7, a, 0.

ARCA AVICULINA. Desh. An. sans Vert. du Bass. de Par., t. i, p. 887, pl. 66, figs. 15—17,
1858.

Spec. Char. A. testa elongatd, angusto-subcylindraced, depressiusculd, inequilaterali,
radiatim eleganterque costellata ; costellis inequalibus, in medio tenuibus; extremitatibus
crescentibus, elevatis, subimbricatis ; umbonibus depressis, brevibus ; ared connexis parvd ;
area dentah paucidentata.

Shell slender, elongate, subcylindrical, somewhat depressed, inequilateral, elegantly
covered with rays or small ribs ; rays smaller or thinner in the centre, enlarging towards
the lateral margins; beaks small, depressed ; area of the connector narrow; dental margin
sparingly furnished.

Length, \sinch; height, 2ths.

Localities. Bracklesham, Bramshaw, Brook (Zdwards), Huntingbridge (Fisher).

This is an elegant species, and, I believe, not very rare. ‘There is considerable
difference between our shell and the figure of the French species, to which it is here
doubtfully referred ; but I feel unwilling to separate them upon what do not appear to be
essential distinctions. ‘There is also a difference between the British specimens from
different localities, those from Bramshaw and Brook being more delicately rayed than
those from Huntingbridge and Bracklesham. In general, our shell appears to be less
cylindrical than that of the Paris Basin species; but in this character our own specimens
vary materially. The principal difference is in the position of the umbo, which is more
eccentric in the British than in the French shell, and in this character the former more
closely approaches 4. cnferrupta, where the siphonal region is alsu broader or higher; but
it differs from that species in being longer, differently rayed, and in having the central
portion somewhat compressed, with an inflated or tumid siphonal region. *

3. Arca BiaNGULA, Lamarck. Tab. XIV, Fig. 1, a—/

ARCA BIANGULA. Lam. An. du Mus., t. vi, p. 219, 1809, and t .ix, pl. 19, fig. 4, a, 4, 1824.
— — Desh. Coq. Foss. des Env. de Par., t. i, p. 198, pl. 34, figs. 1—6, 1824.
— Branperi. J. Sowerby. Min. Conch., t. 276, figs. 1, 2, 1821.

— HyanTuLa. Desh. Coq. Foss. des Env. de Par., t. i, p. 199, pl. 34, figs. 7, 8, 1824.
_ — Goldf. Petr. Germ., vol. i, p. 143, t. 122, fig. 3, a—d, 1826.
Byssoarca Branpert. J. Sow., in Dixon’s Geol. Sussex, pp. 92, 169, t. 111, fig. 23, 1850.

1 Since the above has been in press, I have seen the description and figure of Arca Laekeniana, Le
Hon. (‘ Descr. suce. de quelq. nouv. esp. des terr. tert. Eoc. des env. de Brux.,’ p. 7, No. 15), a species which
more resembles our fossil than does the one to which it is here doubtfully assigned, but the rays upon our
shell are somewhat different ; they are apparently more distant, and have intermediate strize, which are
neither shown nor said to exist.upon the Belgian fossil. I think, however, that when specimens of each
can be compared, they may be found to be identical.

BIVALVIA. 81

Spec. Char. A. testé variabili, plerumqué oblonga, angustatd, subtetragond, sub-
obliqua, valdé inequilaterali, striata; umbonibus distantibus, recurvis; siphoni-regione
producta, biangulata ; striis radiantibus, numerosis, squamoso-granulatis.

Shell variable, for the most part elongately oblong ; somewhat oblique, very inequi-
lateral; umbones distant, recurved; siphonal region much the larger, biangulated; strice
numerous, granulated, and slightly imbricated.

Length, 3 inches ; height, 1 inch.

Localities. Bracklesham, Selsey ; var. 6, Barton.

France, Grignon, Courtagnon, Senlis, Valmondois (Des/.).

The ligamental area in this species has a broad, flat, and deep depression, with chevron-
formed lines, which when the valves are united form lozenge-shaped ornaments imme-
diately beneath the umbo, one within the other, the smaller closely approaching the
hinge-margin ; sometimes there is another set of the lozenge-shaped marks on the siphonal
region, but these latter are more often only parallels to the radiating umbonal lines. In
specimens from Barton this area is tinged with a dark-red colour by the remains of the
ligamental connector. The hinge-margin is furnished with numerous small teeth, rather
more strongly displayed in the young state than in the old. Most of the large specimens
from Bracklesham have the outside much eroded and nearly smooth, like specimens of
A. tetragona that have inhabited some crypt where the movements of the animal have
abraded the otherwise striated surface of the shell. This species is particularly abundant
at Bracklesham, where it attains to large proportions. In the full-grown shell from that
locality there is generally a large sinus, the ventral margin being deeply indented; but in
the younger shells from the same locality this is not so strongly marked, and in some of
those from Barton the valves are quite closed; it is so, however, with various specimens
of A. tetragona. The shell called A. bcangula, from the Bordeaux and Touraine beds, is by
M. Deshayes considered as not identical with the Paris Basin species, and in this I think
he is correct. There is, however, a slight difference between our own shell and that of the
Paris Basin, ours being more finely striated all over, especially so upon the pedal region.
Mr. Sowerby has retained the name of 4. Branderi for the British fossil, which, he
says (p. 169), “‘ differs from 4. d¢angula, Desh., in having a much less acute keel.” The
keel, however, is variable in that respect among the French fossils, and this difference does
not always exist in the British shell. The pedal region in specimens from Barton is some-
times broader or higher than in those from Bracklesham ; this arises from a less smuated
margin, which otherwise contracts the shell at that part; the large rays have generally a
smaller intermediate one, and these are decussated by very visible lines of growth. ‘The
Barton shell may, perhaps, be considered as a variety under the name Brander, but I think
there is not a specific difference ; it much resembles 4. miniata, Desh,

82 EOCENE MOLLUSCA.

4, Arca prpressa, J. Sowerby. Tab. XIV, fig 4, a—e.

ARCA DEPRESSA. J. Sow. Min. Conch., t. 474, fig. 2, 1824.
— — Morris. Catal. Brit. Foss., p. 185, 1854.

Spec. Char. A. testa tenui, elongato-oblongd, valdé inequilaterali, depressd, radiatim
striatd et concentricé decussatd ; striis tenuibus, distantibus, subtuberculatis ; marginibus
ventrali et dorsali subparallelis.

Shell thin, elongately oblong, very inequilateral, depressed, radiately striated, and con-
centrically decussated ; striz thin, and slightly tuberculated; ventral and dorsal margins
nearly parallel.

Length, tths of an inch; height, } an inch.

Localities. Woolwich (Sowerby), Basingstoke (Prestwich).

The specimens of this species that I have seen are very few and imperfect, and the
characters for specific determination are not satisfactorily displayed. The principal distinc-
tion appears to be its depressed form, or shallow valve; the striz upon the exterior Mr,
Sowerby describes as “very distant upon the anterior side (siphonal region ?), and appear
like small knotted threads ;’ those on the shorter or pedal region are close, with inter-
spaces of the same width. The cast of a species of Arca in Mr. Prestwich’s cabinet from
New Cross, Tab. XV, fig. 15, has the above name (in MS.) attached, and I have had it
figured, as it appears somewhat to differ in being more inequilateral; but it is scarcely
possible to determine a species from a cast alone.

5. Arca DunwicuiEnsis, Ldwards, MS. Pl. XV, fig. 6, a, 4.

Spec. Char. A. testd ovato-oblongd, subobliqud, gibbosuld, valdé inequilaterali,
utrdque extremitate late obtusd, in medio depresso-sinuosd, radiatim costellatd ; costulis
angustis prominulis, in siphoni-regione distantioribus ; cardine—?

Shell ovately oblong, slightly oblique, somewhat gibbous, greatly inequilateral ; each
extremity broadly obtuse ; ventral margin slightly sinuated, covered with radiating riblets,
rather distant upon the siphonal region ; hinge—?

Length, 12 inch ; height, iths of an inch.

Locality. Dulwich (Ldwards).

A few specimens of a shell, apparently belonging to this genus, have been turned out
of the “diggings” for the main sewer at Dulwich; they enrich the cabinet of Mr.
Edwards. ‘These specimens, unfortunately, do not exhibit to view the hinge-area; but
the exterior has the form and sculpture which generally characterise the genus 4rca, The
valves have been pushed a little out of their natural position, and display a few elongated
furrows and ridges nearly parallel with the dorsal or outer margin of the shell; these

BIVALVIA. 83

resemble the parallel lines upon 4. heterodonta, Desh. (‘An. sans vert. du Bass. de Par.,’
p. 906, pl. 67, figs. 22—25), but the lines upon our shell appear to be in the area for
connexus, and not upon the dental margin ; this I am unable correctly to ascertain. Our
shell is very inequilateral, and the siphonal region is not only longer, but larger and
higher; the radiations are a little wider or further apart on the larger or broader portion
of the shell than upon the pedal region. This shell resembles, in outline, 4. ob/iquaria,
Desh. (id., p. 893, pl. 67, figs. 8—10, 10 bis), but is larger, shorter, and not quite so
oblique. It is separated from 4. depressa, as well by difference in outline as by the
apparent difference in the hinge-area,

6. Arca Eximta, Hdwards, MS. Tab. XV, fig. 3.

Spec. Char. A. testé elongata, obliqué sub-quadrangulart, valdé inequilaterali, sub-
depressd, radiatim costulaté et concentricé decussatd, punctatd ; umbonibus prominentibus,
distantibus ; area connewtis levigata ; dentibus medianis minimis ; siphoni-regione productd.

Shell elongate, oblique, irregularly quandrangular, very inequilateral, somewhat de-
pressed, punctated, covered with radiating lines or riblets, crossed by distinct lines of
growth ; beaks rather prominent ; area of the connector rather narrow and smooth; teeth
small in the middle of the dental area; siphonal region produced.

Length, sths of an inch.

Locality, Brook (Edwards).

A single specimen of the left valve of a species which appears to be quite distinct,
and to which is attached the above MS. name, is in the cabinet of Mr. Edwards; it is
not quite perfect, and so closely attached to the matrix that I am unable to see the
interior. Its nearest relative is, I think, 4. punctifera, Desh. (p. 202, pl. 32, figs. 13, 14),
but it differs from that species in several characters. he English shell appears to be more
elongated and more inequilateral, and to have the area for connexus larger and broader
than that described in the French shell, in which it is characterized as being so small and
narrow as to bring the umbones almost close together, giving thereby a very small extent
for the marginal separation of the valves. Our shell has the surface regularly rayed, with
rather narrow and rounded single lines, which are decussated by broad and prominent
lines of growth, leaving between each a deep depression or puncture ; and where the rays
are narrowest these punctures are, of course, most numerous. The area for connexus is
broad, flat, concave, and smooth, and widest over the pedal region ; the denticles are close
and numerous, inclining towards the extremity of the hinge-line. Iam unable to see if
the internal edges of the margin be denticulated. 4. ewornata, Desh. (‘ An. sans vert. du
Bass. de Par.,’ p. 889, pl. 69, figs. 1—3), as also A. intersecta, figs. 25——27, resemble it
in some characters.

12

84 EOCENE MOLLUSCA.

7. ARCA GLOBULOSA (°), Deshayes. Tab. XV, fig. 9, a, 6.

Arca GLoBULOsA. Desh. Coq. Foss. des Env. de Par.,t. i, p. 209, pl. 33, figs. 4—6, 1824.

Spec. Char. “A. testdé ovato-oblongd, brevi, gibbosd, globulosd, subcordatd, inequilaterali,
obliquatd, striata, striis alternis minoribus, levigatis ; cardine arcuato, multidentato (°) ;
margine crenato.’—Deshayes.

Shell ovately oblong, short, tumid, or somewhat globular or gibbous, inequilateral,
oblique, and striated ; strize alternately large and small; dental margin slightly curved ;
ventral margin deeply crenulated.

Length, th of an inch; height, 3th of an inch.

Locality. Wighcliff, Barton.

This is not particularly rare. I have referred it, with considerable doubt, to the Paris
Basin shell. It may possibly be a variety, swbglobulosa.

On comparison with French specimens, I find that the English shell is rather smaller,
less quadrate, or more rounded on the siphoni-lateral margin; and the dental area in the
French shell is longer, and furnished with more numerous teeth, 17, 18 (Desh.); our
specimens have four denticles on one side of the umbo and five on the other; those on the
siphonal side are much inclined, almost parallel with the margin at the extremity, and,
from the comparatively great depth of the valve, I imagine that our shell is a full-grown
species, and not the fry of a larger one. The sculpture on the exterior resembles that
upon A. scapulina, the rays being alternately one large and one small; the smaller rays
are nodulous, and the interspaces are decussated, the lines of growth being large, promi-
nent and regular, thickening periodically the smaller rays; but the larger rays are nearly
smooth. ‘There appears to be in this species a small triangular fossette beneath the umbo,
hke that in 4. /evigata, dividing the connector into two different arrangements, as in
Limopsis.

8. Arca impo.ita, J. Sowerby. Tab. XV, fig. 4, a, 3.

Arca IMPOLITA. J. Sow. Geol. Trans., 2nd ser., vol. v, p. 136, pl. 8, fig. 10, 1834.
— — Morris. Catal. Brit. Foss., p. 185, 1854.

Spec. Char, A. testa oblongd, convead, tumidd, levigatd, glabra ; valdé inequilaterali,
pedi-regione brevi, rotundatd ; siphoni-regione sub-quadratd ; marginibus intis integris ;
dorsali et ventrali sub-parallelis.

“'Transversely oblong, very convex; marked with longitudinal rows of punctures ;

anterior portion small, rounded ; posterior rounded ; front parallel to the hinge-line ; shell
thin.’—J. Sowerby.

BIVALVIA. 85

Length, sths inch; height, sths inch.

Localities. Hampstead, Potter’s Bar, Highgate, Haverstock Hill (Hdwards and
Weth erell) :

“Tt approaches 4. cucullaris, Desh. (vol. i, p. 206, pl. 33, figs. 1, 2, 3), but differs
slightly in form as well as in the teeth being all transverse.” —J. Sowerby.

All the specimens of this species that I have been able to see have the two valves
united, and the dentition obscured ; it resembles 4. nitens of the same deposit, but is
less oblique.

A small individual in Mr. Wetherell’s cabinet (fig. 4, c) appears to be free from all
exterior ornament ; it is possible that this may be the result of abrasion. There are also
a few specimens of this genus in the same cabinet from the well at Hampstead, which are
in a mutilated condition, and not sufficiently perfect for determination ; they resemble the
present species in shape, but appear to be more strongly and distinctly radiated.

9. Arca inTERRUPTA, Lamarck. ‘Tab. XV, fig. 2, a, 6.

ARCA INTERRUPTA. Lamk. (non Poli). Ann. du Mas., t. 6, p. 220, No. 5, 1809.
— —_— Desh, Coq. Foss. des Env. de Par., t.i, p. 213, pl. 32, figs. 19, 20, 1824.
— — Id. An. sans Vert. du Bass. de Par., t. i, p. 888, 1858.
— — Morris. Catal. Brit. Foss., p. 185, 1854.

ByssOaRCa INTERRUPTA. J. Sow., in Dixon’s Geol. of Suss., p. 93, t. 111, fig. 21, 1850.

Spec. Char. A. testé obliqua, ovato-oblongd, compressa, valde inequilaterali ; costulaté
et decussatd ; pedi-regione angustiore, siphoni-regione latiore et longiore ; cardine brevi, in
medio edentulo, ad utramque extremitatem recurvo, pauci-dentato.

Shell oblique, ovately oblong, compressed, very inequilateral ; striated and decussated by
lines of growth; pedal region narrow and short; hinge area edentulous in the centre ;
extremities with few oblique denticles ; ligamental area narrow ; umbones approximate.

Length, 1 inch; height, $ inch.

Localities. Bracklesham, Selsey (Zdwards).

France, Grignon, Parnes, Mouchy, Fontenay, Auvers (Deshayes).

A fine series of this shell enriches the cabinet of Mr. Edwards. It is slightly com-
pressed in the centre and contracted in the ventral margin opposite the umbo, but it has
very little gape. he hinge-area contains about six or seven denticles, those on the pedal
side (three or four) are very slightly inclined to the hinge-margin, neither are the three or
four on the siphonal side quite parallel with the dorsal edge. Between the striz or coste,
which strongly denticulate the margins, there is an intermediate ray. Some of the French
specimens are a trifle broader in the siphonal region than in the English shells, and the
intermediate ray is scarcely so prominent.

86 EOCENE MOLLUSCA.

10. Arca Lavieata, Caillat. Tab. XV, fig. 8, a, 6.

Arca L&vicaTa. Caillat. Desc. des quelq. Coq. Nouv., p. 4, pl. 2, fig. 7, 1834.
= — Nyst. Tabl. Syn. des Arches, p. 40, No. 212, 1849.
— = D’ Orb. Prod. de Paléont., t. ii, p. 390, No. 1059, 1850.
— — Pictet. Traité de Paléont., t. iii, p. 551, 1855.
== — Desh. An. sans Vert. du Bass. de Par., t. i, p. 905, pl. 68, figs. 23—26,
1858.
— e1EeGans. S. Wood. Lond. Geol. Journ., p. 3, 1846.
— prm®TeNuIS. Charlesworth. MS. Nat. Hist. Soc. Illust.

Spec. Char. A. testd minutd, glabri, tumidd, ovato-subquadrangulari vel subtra-
peziformi, subequilaterali ; pedi-regione laté semicirculari ; siphoni-regione paulo minore,
angulatd vel oblique truncata ; umbonibus acutis, distantibus ; margine integro, dentibus
in medio interruptis ; fossuld in ared cardinali excavatd.

Shell small, glossy, ovately quadrate or slightly trapeziform ; subequilateral, sub-
equivalve, tumid; pedilateral margin rounded; siphonilateral truncated or angulated ;
beaks distant ; margins smooth; triangular depression in cardinal area.

Length, 7th inch; hezght, 4th of an inch.

Localities. Barton, Bracklesham (Zdwards), Isle of Wight (Charlesworth).

France. Grignon, &c., Calcaire grossier (Desh.).
This elegant little shell is by no means rare in England, and specimens present
‘considerable variation.

T have obtained it also from a small patch of the so-called Upper Marine, which
intervenes between the true freshwater deposits at Hordle.

There is a peculiarity about this and one or two other species hitherto included in the
genus Arca which will entitle them to be placed in a distinct section, perhaps to be
regarded as forming a distinct genus; they present the same difference from Arca that
Lnmopsis does from Pectunculus, having a portion of connexus placed in a triangular pit
immediately beneath the umbo.

M. Deshayes has figured and described two species with this peculiarity in the
connector, viz., 4. /evigata and A. effossa, the latter differing from the former in having
the exterior surface more distinctly cancellated, while the former is described as being
quite smooth, as the name imports. Our little shell corresponds in outline, and pretty
well so in magnitude and relative proportions, with both these species, but it does not
correctly agree with either in the ornamentation, except that there are a few more promi-
nent rays over the angular ridge on the siphonal region; it has the exterior cancellated,
though in a fainter or minor degree than A. effossa, but it is not smooth in perfect
specimens. ‘This, M. Deshayes remarks, is the smallest known species of the genus, and it
is not quite equivalved, the right valve being slightly the larger of the two. It approaches
closely to Z'rigonocelia, and might be called Zrigonodesma.

BIVALVIA. 87

Since my Plate was engraved, I have seen in Mr. Prestwich’s cabinet a small Arca
found by himself at Shapley Heath, and mentioned in the ‘Journ. of the Geol. Soc.,’
1847, p. 390, as an undescribed species. This shell strongly resembles the above, and
as Mr. Prestwich considers the deposit in which it is found as belonging to the Brackle-
sham series, it must, for the present at least, have the same name: it does not, however,
satisfactorily conform to the characters of the Barton shell, neither to the specimens found
at Bracklesham ; in those shells the pedal region is decidedly the larger of the two, and is
longer and more elevated ; the whole shell is also shorter and more tumid. ‘The Shapley
Heath specimens are comparatively longer, and the pedal side is the shorter ; the hinge-area
also appears to have fewer and larger denticles, and the exterior, so far as can be observed,
is quite smooth. I feel unwilling to make another species of it from want of better
materials, but I think it must at least be considered as a variety.

11. Arca Lyrti1? Deshayes. Tab. XV, figs. 12, a, 4, and 13, a, 6.

Arca LYELLI. Desh. Coq. Foss. des Env. de Par., t. i, p. 200, pl. 34, figs. 9—11,
1824.
— — Id. An. sans Vert. du Bass. de Par., t. i, p. 873, 1859.

Spec. Char. A. testa elongata, subcylindraced, gibbosuld, inequilaterah, plus minusve
trregulart, sulcaté aut radiatim costulatd et concentricé squamoso-lamellosa vel tuberculoséd ;
siphoni-regione longiore angulaté aut oblique truncataé; umbonibus minimis, depressis,
obliguis ; ared connextis angusta, dentibus medianis wregularibus ; marginibus crenulatis.

Shell transversely elongate, subcylindrical, slightly tumid, inequilateral, more or less
irregular in outline, covered with radiating and rounded ridges decussated by lamellated
lines of growth ; siphonal region the longer, and obliquely truncated ; umbones depressed ;
area for connector small, narrow ; margins crenulated.

Length, sths of an inch,

Localities. Barton (Hdwards), Colwell (H. H. Wood).

This species seems to be rare in our Eocene beds. A few specimens from Barton
are in Mr. Edwards’s cabinet, and the Rev. H. H. Wood has kindly sent me a specimen
from Colwell Bay.

The shell from the French beds, to which this is with some slight doubt referred, is
said to be variable; and M. Deshayes has proposed two new species, 4. conforta and
A. lamellosa, which he thinks, however, may be ultimately united to 4. Lyell, and I am
inclined to the same opinion. ‘I'he shell represented by fig. 13 of our Plate, which I at
first imagined to be distinct, may perhaps be referred to /amedlosa, and that by fig. 12 to
contorta ; these all so closely accord with 4. clathrata, that I am doubtful whether the
‘Touraine shell be anything more than a variety induced by difference of conditions. Among
the few English specimens that I have seen, there is considerable variation ; in one the
dental area has only a few large teeth, in another of the same size this margin is studded

88 EOCENE MOLLUSCA.

with double the quantity of denticles ; in some the margin is crenulated all round, in others
the central portion appears to be free from crenulations, and in 4. contorta the margin is
said to be smooth; this variation is perhaps dependent upon the state of preservation of
the specimens. The surface of our shell is covered with rounded rays more or less broad
or numerous, and these rays generally project at the margin, particularly on the siphoni-
lateral region ; this is more especially the case in the shell fig. 12, where the diagonal or
carinal ridge is prominent, and the rays are more distinctly Jamellated. The position of the
umbo is not a permanent character, some specimens being more inequilateral than others.

12. Arca MopioLiFoRrMIs, Deshayes. Tab. XIV, fig. 5, a, 4.

ARCA MODIOLIFORMIS. Desh. Coq. Foss. des Env. de Par., t.i, p. 214, pl. 32, figs. 5, 6, 1824.
— — Id, An. sans Vert. du Bass. de Par., t. i, p. 896, 1858.
a ~ Potiez et Mich. Gal. de Douai, t. ii, p. 111, No. 16, 1844.

Spec. Char. A. testa elongato-obliqud, ovatd vel irregulariter trapeziformi, valdé
mmaquilateralt, modioliformi ; radiatim striatd, striis in siphoni-regione depressis, undulatis
distantioribus ; cardine in medio edentulo.

Shell elongately oblique, ovate or irregularly trapezoidal, very inequilateral, radiately
striated, the striz on the siphonal region somewhat undulating and distant; hinge-line
without denticles in the centre, with a few only at each extremity.

Length, 1 inch; height, ths of an inch.

Localities. Stubbington (Ldwards).

France, Cuise-Lamothe, Valmondois (Deshayes).

This is apparently a tolerably well-marked species. I have seen only three British
specimens ; these correspond so well with the Continental shell, that I think there will be
no dissent from the identification.

M. Deshayes gives two varieties of his species in his first work, but in his more recent
one he has separated what were formerly included under the above name. Our shell
appears better to agree in form and in the exterior ornament with what he has called
A. Rigaultiana ; but the ligamental area is narrower, neither has the British fossil so many
denticles. Old shells will often have the area of connexus enlarged, but the central
portion of the dental area in that case has the denticles obliterated, somewhat after the
manner of those in Pectunculus.

13. Arca nitens, J. Sowerby. Tab. XV, fig. 5 a, 3.

ARCA NITENS. J. Sow. Trans. Geol. Soc., 2nd ser., vol. v, p. 136, pl. 8, fig. 9, 1834.
_— — Prestwich. Geol. Journ., 1847, p. 401.

Spec. Char. A. testdé elongata, obliqud, subtrapezoidali, convexd, tumidd, levigatda

BIVALVIA. 89

glabra, valdé inequilaterali ; pedi-regione brevi, rotundatd, siphoni-regione altiori, sub-
cuneiformi vel obtuse angulatdé ; umbonibus prominulis ; marginibus integris.

Transversely oblong, convex, smooth, and glossy; pedal region the shorter; siphonal
region obtusely wedge-shaped; front oblique; shell thin; beaks slightly prominent ;
inner margin of valves smooth.

Length, 3 meh; height, ths of an inch.

Localities. Hampstead (Wetherell), Primrose Mill (Hdwards).

“Some specimens have a few punctures, in which character they approach 4.
impolita.” —Sow.

This species is not quite so abundant as 4. impolita, which it much resembles. The
difference which appears to have caused the separation is a little more obliquity in the
siphonal region of this species. The ventral margins appear to be free from crenulations,
or at least, if they possessed them, they were very small and fine, and there is no sinuation
for a byssus. The punctures spoken of by Mr. Sowerby arise from the want of continuity
in the smoothness of the outer coating by which the radiating lines are seen distinctly
separated, showing punctures or depressions between them and the decussating lines of
growth.

14. Arca pranicosta, Deshayes. Tab. XIV, fig. 2, a, 6.

ARCA PLANICOSTA. Desh. Coq. Foss. des Env. de Par., t. i, p. 204, pl. 32, figs. 1, 2, 1824.
— — D Orbigny. Prod. de Paléont., t. 2, p. 390, No. 1047, 1850.
— — Desh. An. sans Vert. du Bass. de Par., t. i, p. 878, 1858.

Byssoarca DupLicata. J. Sow., in Dixon’s Geol. of Suss., p. 93, pl. 3, fig. 22, 1850.

Spee. Char. A. testa elongatdé, subcylindraced, convewxiusculd, inequilaterali, tenut,
in medio depressiusculd ; siphoni-regione valdé longiore, obtusé angulatd ; pedi-regione
converd, marginibus ventrali et dorsali subparallelis ; radiatim costellatd costellis SEPlus
planulatis, bifurcatis, aliguando granulatis ; umbonibus depressis ared ligamenti angustd ;
dentibus in medio minimis, utrdque extremitate obliquis.

Shell elongate, subcylindrical, inequilateral, siphonal region much the longer, central
portion depressed ; pedilateral margin convex, siphonilateral margin obtusely angulated,
dorsal and ventral margins nearly paraliel ; radiately costated with flattened and some-
times divided rays; umbones depressed, ligamental area narrow; teeth small in the
centre, inclining towards each extremity.

Length, 2 inches ; height, 1 inch.

Localities. Bracklesham, Bramshaw, Brockenhurst, Brook (Zdwards).

France, Senlis, Parnes, Valmondois, Auvers, Le Fayel (Deshayes).

This is by no means rare at any of the localities cited, but I have not seen it from

Barton. It appears to correspond with the Paris Basin shell of the above name, and it

90 EOCENE MOLLUSCA.

is closely allied to 4. darbatula ; it differs from the Barton 4. appendiculata in being more
elongated and less inflated, and the siphonilateral margin is more rounded, less angular,
and not so much produced. The rays also are more prominent in appendiculata, and the
lines of growth more distinct, giving to that shell a more elaborate ornamentation ; it has
also a larger or broader ligamental area; the extremity of the hinge-line on the pedal
side is more angular, and there is a difference in the dentition. This species also appears
to attain to larger proportions. The only variation that I can detect between the English
shells and the French species, to which they are referred, is that the rays upon the siphonal
region of the Engish shells are not quite so broad as upon those from the Paris Basin.
The margin of the interior of our shell is slightly and irregularly denticulated. Consider-
able variation exists among specimens in regard to proportional dimensions, more particu-
larly in those from Huntingbridge; in some the height is equal to three fifths of the
entire length, but in others the shell is very cylindrical, with a height not equalling half
the length.

In the list of fossils from the Eocene deposits of this country, given by Mr. Prestwich
in his paper on the London Clay, published in the ‘Journal of the Geol. Soc.,’ vol. in,
p- 401, is the name of 4. dardatula, as from Barton and Bracklesham. I have not seen a
specimen from any of our British deposits that can be safely referred to that species ; the
nearest approach to it are some of the elongated specimens of this species from Hunting-

bridge.

15. Arca tecuLaTa, Ldwards, MS. Tab. XV, fig. 10, a, 3.

Spec. Char. A. testa elongata, subcylindraced, depressd, lucidd, tenut, inequilaterali ;
obsoleté costatd concentricée decussatd ; pedi-regione sub-attenuatd, siphoni-regione paulo
dilatatd, umbonibus minimis, remotis, prominulis ; ared connextis angustd, lanceolaté,
levigala ; dentibus —?

Shell elongate, somewhat cylindrical, depressed, glossy, thin, and inequilateral ; obso-
letely or lightly rayed, and decussated by lines of growth; siphonal region a little the
broader; umbones small, remote and prominent; area for ligament narrow and smooth.

Length, %ths inch ; height, ith inch.

Locality. Bracklesham (Hdwards).

This appears to be intermediate in form between 4. angusta, Desh. (‘ Coq. foss. des
Env. de Par.,’ t.1, p. 201, pl. 32, figs. 15, 16), and .4. Zuceda, Desh. (‘ An. s. vert. du Bass.
de Par.,’ t. 1, p. 891, pl. 67, figs. 26—28), it is nearer to the latter, but it is not so broad
in the siphonal region. Ours is an elegantly formed shell, and the only specimen I have
seen which has the two valves united is the one figured. The surface is ornamented with
rays irregularly distant; those on the pedal region are narrow and close, increasing in
size as they approach the siphonal region, where they are broad and flat with a narrow
line between them; these are crossed by a broad flat ridge of growth, which is smooth,

BIVALVIA. 91

and it imparts a gloss or polish to the exterior like that of 4. /wcida. The dental area of
our shell appears to be well furnished with teeth, and there is a slight sinuation in the
ventral margin.

16. Arca tessELLata, Fisher, MS. Tab. XV, fig. 14, a, d.

Spec. Char. A. testé crassd, elongata, ovato-oblongd, depressé, sub-obliqua, inequi-
laterali ; siphoni-regione angulo decurrente definitd ; sulcis quatuor crassis, granosis ornatda ;
umbonibus depressis, obliquis; area connexiis obliqud, sulcatd, ared cardinalt arcuatd in
medio edentuld, ad extremitatem pauci-dentaté ; margine ventrali sinuoso, integro.

Shell elongate, of an ovately oblong form, depressed, slightly oblique, inequilateral ;
siphonal region with an angular elevation, ornamented with four thick rays; beaks
depressed, oblique ; area of connector narrow, oblique, and ridged angularly; dental area
slightly curved, with few teeth at the extremities, central portion plain; ventral margin
sinuated, edges plain.

Length, \% inch; height, ?ths of an inch.

Localities. Brook (Fisher), Huntingbridge (Adwards).

This appears to be closely related to two or three species found in the Paris Basin, but
with no one of which does it accord so as to be satisfactorily regarded as anidentity. It is
not far removed from 4. rwdis, Desh. (‘ Coq. foss. des Env. de Par.,’ t. 1, p. 210, pl. 33,
figs. 7, 8), but the rays and decussating ridges of that species are larger and coarser than
they are on our shell, and the dental area is different. 4. Moriert, Desh. (‘ An. vert. du
Bass. de Par.,’ p. 874, pl. 65, figs. 18, 19), also resembles our shell, but it has a less pro-
minent and less distinctly marked angular ridge, running from the umbo diagonally across
the siphonal region. The rays which ornament our shell are broad and flat, separated by
a deep and narrow depressed line, decussated by distinct lines of growth, which imbricate
the rays on the larger side. ‘The adductor-muscle-marks are large, particularly the oral

one, and the mantle-mark is not very near to the margin of the shell; there is also a long

pedal-muscle-mark under the dental margin on the siphonal side. The teeth of our speci-
mens are not in very good condition, but they appear to have been numerous, and those
on the pedal side are slightly inclined. ‘There is a sinus or indenture in the margin for a
byssus, and the siphonal region is broader or higher than on the pedal side.

A fossil apparently identical with this species has recently been obtained at Lattorf,
Magdeburgh, by Herr A. von Koenen, in a deposit of the Upper Locene (or in what is
called by the German geologists Oligocene) period. ‘The German specimens are, however,
much larger than our own. One perfect individual measures three and a half inches, and
a fragment of the same species indicates a length of nearly five inches.

13

92 EOCENE MOLLUSCA.

17. Arca tumrscrns, Hdwards, MS. ‘Tab. XV, fig. 1, a, 3.

Spec. Char. A. testa mediocri, subquadrangulari, sub-inequilaterali, equivalvi, gibbosd
vel tumidd; radiatim tenuissimé striatd et concentricé decussatd, politd; siphoni-regione
longiore, vie latiore ; marginibus dorsal et ventrali subparallelis, umbonibus approximaitis,
depressis ; areé cardinali angusta.

Shell of moderate size, subquadrangular, slightly inequilateral, equivaive, gibbous or
tumid, finely radiated, and decussated by slender concentric lines of growth, glossy ; dorsal
and ventral margins nearly parallel; beaks small or depressed, with a narrow ligamental
area.

Length, sths; height, sths of an inch.

Localities. Clarendon, Brook (#dwards).

Mr. Edwards’s cabinet contains several specimens of this species, in good. preservation,
and they appear to deserve a distinct specific name. ‘The shell, in some characters,
resembles 4. dmpolita, but it is more tumid, more equilateral than that species, and it is
also more quadrangular, and it is polished and glossy ; the very fine striae with which it
is covered are scarcely visible to the unassisted eye; the lateral margins are roundedly
angular, and the siphoni-lateral region is rather the broader or higher of the two. It is a
handsome shell, resembling, in some slight degree, our common recent species A. /actea.

18. Arca Wessteri, Porbes. Tab. XV, fig. 11, a, 4.

Arca WessTERI. Forbes. Mem. Geol. Sury., 1856, p. 150, pl. 3, fig. 8.

Spec. Char. “ T. parvdé, ovato-oblongd, modioliformi, transversim sulcaté, radiatim
striata, anticé angustiori, posticé latiori, effusd, sub-carinatd ; striis posticis elevatis, acutis,
striis ceteris obscuris; carind rotundatd ; cardine interrupto, dentibus prominentibus,
distantibus.”

“A small, depressed, modioliform shell, transversely sulcated and with radiating striz ;
the anterior narrow, the posterior part spread out and somewhat carinate; the posterior
strie are elevated and acute.”

“The umbones are placed near the anterior margin, and the middle part of the car-
dinal area is without teeth. The teeth are prominent and distant.”—Worris.

Length, :ths of an inch; height, half the length.

Locality. ‘From the Bembridge series.” (Morris.)

This is a pretty little species, and appears to be confined to the Upper Eocene Deposits.
Its principal distinctions are the form of the siphonal region and the ornament with
which it is covered. The shell is rather tumid, and a very obtusely angular ridge or

BIVALVIA. 93

rounded projection extends from the umbo to the base of the siphonilateral margin ; the
radiating strize are close and regular upon the pedal and ventral regions, but upon the
dorsal slope of the siphonal region these rays are more than usually distant, and are some-
what nodulous ; it is very inequilateral, with a recurved and rather prominent umbo.

CUCULLAA.! Lamarck, 1801.

Generic Character. Shell equivalve, inequilateral, trapeziform or subquadrate, ven- —
tricose ; valves closed and striated; umbones remote, separated by a wide and concave
ligamental area; anal muscular impression bounded by an elevated ridge ; hinge linear,
furnished with a few teeth, generally lateral and oblique, but parallel with the hinge-line at
the extremities ; connexus ligamental.

The shells of this genus approach so closely to some of the drce, that it is doubtful, in
the opinion of several naturalists, if there be any good character by which the two can
be generically separated. The principal distinction is its subquadrate outline and inflated
form, for many of the Ark shells of the older rocks have their dental apparatus with a very
similar arrangement, the lateral teeth being few and oblique, sometimes parallel with the
hinge-line. Mr. Lycett proposed a genus under the name Macrodon for certain fossils of
the Oolitic Formation, in consequence of the hinge-denticles differing somewhat in their
number and position ; those on the pedal side of the margin being almost at right angles
to the hinge-line, while at the opposite extremity they are parallel with it, appearing thus
to combine or unite the two genera, 4rca and Cucullea. The British species, Arca rari-
dentata, has the teeth much inclined on both sides. Very many fossils have been placed in
this genus, beginning as low as the Silurian Rocks and ranging up to the present period ;
only one living species is known which truly resembles the typical form, and that is an
Oriental shell. Some of the fossil species have the umbones inflected in a subspiral
manner, but a commencement of this form may be seen in some of the Arce.

CucuLLma DecussaTa, Parkinson. Tab. XVII, fig. 8, a—c.

CucuLLz#a Decussata. Park. Org. Rem., vol. iii, p. 171, t. xiii, fig. 1, 1811.
— — J. Sow. Min. Conch., t. 206, figs. 3, 4, 1818.
_ CRASSATINA. Morris. Catal. Brit. Foss., p. 197, 1854.
_ _ Prestwich. Quart. Journ. Geol. Soc., 1854, p. 109.

Spec. Char. Testd transversd, ovato-oblonga, gibbosd, incrassatd, obliqua, inequilaterali,
decussatim striatd, in medio compressiusculd ; pedi-regione brevi, obtusd, siphoni-regione

1 Ety. Cucullus, a hood. Type, Arca cucullus, Linn.

94 EOCENE MOLLUSCA.

subangulald ; ared connexis angusté; sulcis raris exaratd; marginibus denticulatis ;
dentibus lateralibus tribus.

Shell transverse, ovately oblong, inflated, thick, oblique, and inequilateral, striated and
decussated, slightly compressed in the middle of the shell; pedal region short ; Jigamental
area rather narrow, with few and obsolete chevron-form marks; margins denticulated,
three lateral teeth on each side.

Length, 2 inches ; breadth, 13 inch.

Localities. Faversham (Crowe), Herne Bay, Richborough, Oakwell, near Faversham,
Nash Park, near Boughton (Prestwich).

This shell is considered by Professor Morris, in his ‘ Catalogue of British Fossils,’ as
identical with Cucullea crassatina, Lamk. ; but, although there is a very close approxima-
tion, I am doubtful of their identity; and, as I am not imposing a new name, I prefer
the British fossil should remain with the one under which it was figured and described by
Parkinson and Sowerby. ,

On a comparison of the English shells with specimens in my own cabinet from
Beauvais, I find the following differences :—The French shells appear to be more inflated,
and they have a more prominent, angular, and distinct ridge diagonally across the
syphonal region, and the English shells are comparatively longer; neither can I see the
great inequality between the two valves which is so conspicuously shown in the French
specimens ; the rays upon our shell are large, wide, flat, and bipartite, and these rays are
more nearly alike upon’the two valves than are thoseof C. crassatina. The dental area is
furnished with a few teeth at each extremity of the line; those on the siphonal side are
about three or four in number, and parallel with the hinge-margin; at the opposite ex-
tremity there are about the same number, and they are also inclined; all of them are
vertically striated, or rather denticulated, but more finely so than are either of the French
species, and in the centre of the hinge-line are a few small teeth in a vertical direction ;
these are also finely nodulous ; the margin is crenulated by the outcrop of the rays.

PECTUNCULUS, Lamarck, 1789.

Gen. Char. Shell equivalve, orbicular, convex, or lenticular, nearly equilateral, smooth,
or radiately striated ; umbones central, generally distant, divided by a striated area for
connexus, which is wholly external or ligamental; hinge with a curved row of transverse
or angular denticles ; adductors nearly equal, palleal line simple, margins crenulated ; the
shells in the living state are generally covered by a thick and velvety epidermis.

Animal with the margins of the mantle simple, sometimes studded with minute ocelli;
foot large, crescent-shaped, capable of considerable expansion, so as to form a disc, on
which it is said to be able to move; this foot is supplied with retractor-muscles, the im-

BIVALVIA. 99

pression of which may be generally seen, one on each side and above the adductors, within
the extended dental margin.

Although the mantle is generally open all round, the animal is capable of contracting
or uniting the edges on one side, so as to form two openings, one for the incoming
current and the other for the outgoing, being the commencement of the true siphons.

The known recent species of the genus are about sixty or seventy, and perhaps a similar
number in the fossil state ; these last are very difficult of determination, from the generally
slight deviations in the form of the shell, the normal condition being nearly lenticular, the
specific distinctions depending principally upon the sculpture of the surface or dental
characters; but these teeth are very fallacious, as some are obliterated by age.

The peculiar form of these shells are favorable to their preservation, offering, as they
do, a protection from mutilation, and specimens are often in high perfection.

The genus, im the recent state, has a wide geographical extension, but the species are
somewhat restricted in their range; they are principally inhabitants of warmer regions, .
although 2. glycimeris is living in the British seas, and P. septentrionalis in those of the
north-west coast of America. A species found in the Eocene deposits of North America
is said to be identical with one of our own fossils of the same age. It is most difficult, as
before observed, to determine identity in shells of this genus; but, assuming it to be as
so stated (which I much doubt), we may, I think, fairly place this species in the same
category as Terebratulina caput-serpentis, Kellia suborbicularis, and many other living
molluscs, whose localities at the present day are separated by apparently impassable
barriers. We are not able now to trace these animals, whose localities are so unconnected,
to what may be assumed as a common ancestry for each species thus identified. Whether
these apparently identical forms are descendants of ancestors belonging to the same species
once living together in close geographical contiguity, or whether they are forms having a
distinct origin, but presenting no difference by which the malacologist can separate them
from the typical species, we have at present not the materials to determine.

1. Pectuncuus Brevirostris, J. Sowerby. Tab. XVI, fig. 8.

PECTUNCULUS BREVIROSTRIS. J. Sow. Min. Conch., t. 472, fig. 1, 1824.
— -- Id. in Dixon’s Geol. of Suss., p. 225, t. 14, fig. 32, 1850.
— BREVIROSTRUM. Morris. Catal. Brit. Fos., p. 219, 1854.
— PULVINATUS. Mantell. Geol. of Suss., p. 273, 1822.

PectuncuLus. Smith. Strata Identif., t. 11, fig. 3, 1816.

Spec. Char. P. testa suborbiculari vel obovaté, convexo-lenticulari viv inequilaterali,
sub-symmetricd ; radiatim obsolete costellatd ; concentricé striatd ; umbonibus brevibus de-
pressis ; ared conneaxtis magna, ared dentali arcuaté ; dentibus paucis magnis ; marginibus
crenulatis.

96 EOCENE MOLLUSCA.

Shell suborbicular, slightly ovate, tumidly lenticular, nearly equilateral and sym-
metrical ; covered with obsolete radiating ridges, and concentrically striated ; beaks short
or depressed; area of the connector large, dental margin curved, teeth few and large;
margins crenulated.

Diameter, 2 inches.

Localities. Bognor (Sowerby), Reading (Morris).

This is a long and well-known shell at Bognor, where it has been found in abundance,
with the valves generally united, and their ventral margins closed; the area for the liga-
ment is rather wide, and ornamented with about half a dozen diverging depressed
lines, and these oftentimes bear vertical strice, the impression of the linear composition of
the hgament. The radiating rays of the exterior are broad and depressed, separated only
by a thin, narrow line.

2. Pectuncuus pecussatus, J. Sowerby. Tab. XVI, fig. 7 a—d.

PEcTUNCULUS DECUsSATUS. J. Sow. Min. Conch, t. 27, fig. 1, 1812.
oo — Id. in Dixon’s Geol. of Suss., p. 116, t. 14, fig. 7, 1850.
_ — Smith. Strata. Identif., t. 11, fig. 10, 1816.

Spec. Char. P. testé suborbiculaté vel obtuse et irregulariter quadrangulari, equi-
laterali, tenui, depressiusculd ; radiatim costellatdé, concentricé striatd, decussaté; aredé
connexts bipartitd; aredé dentali arcuati, multidentaté ; umbonibus acutis ; marginibus
integris.

Shell suborbicular or obtusely and wregularly quadrangular, equilateral, thin, and
somewhat depressed ; radiately striated, and decussated by lines of growth ; area of the
connector bipartite ; dental margin curved and well filled with teeth ; beaks sharp, margins
smooth.

Length, sths; height, sths of an inch.

Localities. Highgate (Wetherell), Bognor (Dixon), Basingstoke (Prestwich), Clarendon,
Haverstock Hill (Zdwards).

This is abundant at Highgate, and Mr. Sowerby has figured a specimen from Bognor,
where, I believe, it is rare. The specimens from Highgate are generally in a good state of
preservation except at the umbones, nine tenths at least are there broken. The outline of
this species is more quadrangular than in the generality of the genus, especially at the
siphonilateral margin, and the shell is rather longer than it is high. ‘The surface is
prettily ornamented by the lines of growth, decussating the rays, by which they are made
slightly nodulous; the radiating lines are occasionally distant, with one to three interme-
diate or smaller rays. The radiations of the mantle are generally impressed upon the
interior of the shell, and the impressions of the adductors are very large. The area for the
connector is somewhat peculiar, having a large obtusely angular depression, and it is bipar-
tite, like that of Zimopsis; this depressed ligament is strongly marked with lines at right

BIVALVIA. 97

angles to the dental margin (fig. 7, c,d), showing the linear fibres of which it is composed,
these being the more durable portion, are alone remaining. Fig. 14, Tab. XIX, is the
representation of a young individual from Clarendon; it is of a rather more elongated
form than the generality of the larger specimens, but its peculiarity is in the area for con-
nexus, where it shows a bipartite character precisely resembling that which is considered a
generic distinction in Zimopsis ; in this young shell the triangular cavity is not only small,
but it is comparatively much less than in the adult shell. The connexion between the
two genera in the immature state appears so close as not to permit of generic separation,
showing, as in many other animals, a very near relationship in the early part of life, diverging
by the increase of age.

Some of these young shells have the rays upon the exterior fewer and more prominent,
resembling those upon P. deletus, the intermediate rays being small and scarcely per-
ceptible ; they are not peculiar to the Clarendon specimens, but may be seen also on young
shells from Haverstock Hill. Casts resembling this species have been found at Sheppey.

3. PrectuncuLus pELEtuS, Solander. Tab. XVI, fig. 3, a, 6.

ARCA DELETA. Solander, in Brand. Foss. Hanton., p. 97, pl. vii, fig. 97, 1766.
PEcTUNCULUs costaTus. J. Sow. Min. Conch., t. 27, fig. 1, 1813.
— DELETUS. Morris. Catal. Brit. Foss., p. 219, 1854.

Spec. Char. LP. testé orbiculatd, convead, vel regulariter lenticulaté ; radiatim
costaté ; costis equalibus angustis, acutis ornatd ; concentricé striata ; striis creberrimis ;
costis aliquando tuberculatis ; umbonibus subelevatis, recurvis; cardine valdé arcuato,
multidentato.

Shell orbicular, convex, or lenticular, radiately costated ; ribs equal, sharp, and narrow;
concentrically striated lines of increase numerous, close, ribs sometimes tuberculated; beaks
slightly elevated, recurved ; hinge-line with numerous teeth.

Diameter, 13ths of an inch.

Locality. Barton.

This is an abundant shell at Barton. I have not seen it from any other locality.

Some specimens are almost smooth, or at least are covered with only depressed rays,
without the appearance of abrasion, others are beautifully ornamented with narrow sharp
ribs, varying from twenty-five to thirty-five; and these are, in very well preserved specimens,
covered with tubercles produced by the prominent lines of growth. ‘The dental area is
well furnished with a continuous line of teeth varying from twenty to thirty. The
margin of the valves is regularly denticulated, and these are not the extension of the ribs,
but appear to be quite independent.

A shell found by Herr A. von Koenen at Lattorf appears to agree with the smooth
variety of this species.

98 EOCENE MOLLUSCA.

4. PecruncuLus eLososus, J. Sowerby. Tab. XVI, fig. 9.

PrcTUNCULUS GLOBosUs. J. Sow. in Dixon’s Geol. of Sussex, p. 170, t. 3, fig. 20, 1850.

Spec. Char. P. testé crassd orbiculari, globosd, sub-equilaterali, equivalvi, levigatd,
aut obsoleté radiaté ; margine cardinali arcuatd, umbonibus prominentibus, marginibus
crenulalis.

Shell thick, obliquely orbicular, globose, slightly inequilateral, equivalve, smooth, with
faint or obsolete radiations; hinge or dental area curved; beaks prominent; margins
crenulated.

Diameter, 1 inch.

Locality. Bracklesham (Dizon).

This appears to be more tumid at the upper part than any other species. There is
a resemblance between it and provimus, which is common at Barton; but that shell is
always more or less oblique, with a sharper or Jess tumid umbonal region, and this shell,
as its name implies, is more globose.

5. Puctuncutus Piumsreapiensis, J. Sowerby. Tab. XVI, fig. 6, a, 3b.

PECTUNCULUS PLUMSTEADIENSIS. J. Sow. Min. Con., t. 27, fig. 3, 1813.
— —_ Morris. Catal. Brit, Foss., p. 219, 1854.

Spec. Char. LP. testé tenui, lenticulart vel orbiculato-subquadratd, equilaterali ;
obsolete costatd vel radiata, concentricé striatd ; umbonibus depressis ; marginibus crenulatis ;
ared connexts parva.

Shell thin, lenticular, with a somewhat roundedly quadrangular outline; equilateral,
obsoletely costated or radiated; beaks depressed, with a small area for the connector;
margins toothed.

Diameter, 14 inch.

Localities. Plumstead; Upnor; Katesgrove, near Reading.

This is thinner than the generality of the genus, and the rays upon the exterior are
broad and rounded; it resembles drevirostris in having a small beak, but that shell is
more oblique, with the rays less prominent, the hinge less curved, and the denticles fewer.
Tn the ‘Geol. Journ.,’ vol. x, p. 120, 1854, this species and drevirostris are united with
P. terebratularis, Lamarck. M. Deshayes (p. 852) considers the two latter as distinct,
and I am disposed to agree with him, but I believe also that the above-named Plwin-
steadiensis is entitled to a distinct specific position.

BIVALVIA. 99

6 Prcruncutus proximus, &. Wood. Tab. XVI, fig. 5, a—e.

Spec. Char. P. testé oblique suborbicularé, inequilaterali, crassd, tumidd ; obsolete
costulaté vel radiata ; siphoni-regione subangulato ; umbonibus prominulis ; area connexiis
obtuse triangulari ; dentibus numerosis.

Diameter, 13 inch.

Locality. Barton (Hdwards).

This species differs from P. pulvinatus, with which it has been hitherto associated, in
being more oblique, more elevated, and less tumid, and there is always a greater extension
of the siphoni-lateral. margin, with a depression or flattened space above a slight ridge,
extending from the umbo on that side, particularly in elevated specimens. ‘The shell in
general has a greater diameter in the direction of its height, and in these specimens the
ligamental area is larger or higher, with the dental margin broader than in others ; but its
principal distinction is the angular ridge on the siphonal side. ‘Tab. XVII, fig. 11, is
from Huntingbridge, and may, I now think, be referred to this species; it- was at first
supposed to be a Zimopsis, but the character which induced that name is probably acci-
dental ; it is, however, smoother and thinner than the generality of the Barton specimens.

There are two or three species from the Paris basin to which our fossil bears a close
relationship, but to no one of them can I satisfactorily assign it. P.-depressus (Desh.)
resembles it in outline, but our shell is neither depressed (‘‘ depressissima”’), nor thin; it
is crenulated all round, not “‘ mince et lisse antérieurement et postérieurement ;” neither
is the “area ligamenti minima.”

7. Pecruncunus Putvinatus, Lamarck. Tab. XVI, fig. 2, a, 8.

PECTUNCULUS PULVINATUS. Lam. Ann. du Mus., t. vi, p, 216, and +. ix, pl. 18, fig.
9, a, 0.
_ — Desh. Par. Foss., p. 219, pl. 35, figs. 15—17.
— _— Ib. Coq. Caract. des Terr.,-pl. 5, figs. 9, 10.
—_ — ‘Bronn. Leth. Geogn., t. 1, p. 936, pl. 39, fig. 4,
— —_ Goldf. Petr. Germ., p. 160, No. 5, pl. 126, fig. 5.
_— — Nyst. Belg. Foss., p. 250, pl. 19, fig. 8, a, 5.
— — “J. Sow. in Dixon’s Geol. of Suss., p. 93, t. 11, fig. 25.
_ — Bronn. Syst. der Urw., p. 52, pl. 5, fig. 13, 1824.

Spec. Char. P. testa orbiculatd, ventricosd aut pulvinata, subequilaterali viz obliquatd,

striato-costulaté vel radiata, tenué decussaté ; margine crenato, crenults brevibus ; ared car-
dinali perangustd, umbonibus depressis.
Shell orbicular or lenticular, ventricose or puffed up, nearly equilateral, slightly
14

100 EOCENE MOLLUSCA.

oblique ; radiated or obsoletely costulated, finely decussated; margin toothed, area of
connector rather narrow ; beaks depressed.

Diameter, 2 inches.

Localities. Stubbington (Zdwards). ;

Belgium : Le calcaire d’Afflighem et d’Audenarde, Kleyn Spauwen (Wys?).
France: Grignon, Courtagnon (Deshayes).

A large number of fossils from various localities and from various formations have
been figured and described under the above name; Brongniart has given it to a species
from the neighbourhood of Turin, and Dubois to one from Volhynia, but these are, perhaps,
not strictly within what are called specific limitations. The principal character, as its
name imports, is a tumid or puffed-up appearance of the specimen, with a very slight
deviation from the orbicular or rather circular form of the margins. There is also a
slight angularity on the siphonal region, as is often the ease in shells of this genus. The
dental area is curved and well furnished with teeth, and the area for connexus is rather
small, but it increases considerably as the shell enlarges, and it is comparatively wider in
the old shell, where the ligamental portion of the connector has obliterated or overlapped
the denticles in the centre of the hinge area. The surface of the English specimens is
seldom or never in such a good state of preservation as those from the Paris basin, where
the small interstices between the rays and the lines of growth may be distinctly seen,
giving a slightly punctured appearance to the exterior, and in those shells a portion of the
connector is often preserved.

8. PzcruncuLus auasipuLvinatus, S. Wood. Tab. XVI, fig. 1, a, 4.

Spec. Char. LP. testdé lenticulato-complanatd, compressa, equilaterali, equivalvi, sub-
transversd ; radiato-striatd, striis depressis, obsoletis ; concentricé decussatd ; marginibus
crenulatis ; ared connexis perangustd ; umbonibus depressiuscults.

Shell compressed or depressedly lenticular; equilateral, equivalve, rather transverse or
elongated ; covered with depressed and obsolete striz ; decussated by obscure or irregular
lines of growth ; margins crenulated ; area of connector narrow ; beaks depressed.

Diameter, 24th inches.

Locality. Bracklesham.

This has hitherto been placed in cabinets under the name of P. pulvinatus, var., but I
think the differences are such as to entitle it to a separate specific position, and the speci-
mens themselves appear to show a permanence of difference which give them as good a
claim for isolation as most others in this perplexing genus. Our shell is much more com-
pressed than the true pulvinatus, and the proportions in this are also different, the shell
being more transverse or elongated. It differs also from the French shell called pseudo-
pulvinatus, which is neither so compressed nor so transverse as our present species. I

BIVALVIA. 101

have separated the two British shells in consequence of the very great difference in the
tumidity or convexity displayed between them, and this difference appears to be constant.
The Stubbington shell measures 2:th inches in diameter, with 1:ths inch in depth or
tumidity of the united valves, while the Bracklesham shell is longer than it is high, and it
has a depth of less than an inch between the inflation of the two valves. There is also a
difference in the hinge ; this latter shell has a narrower dental area, with a place for con-
nexus also smaller.

9. Pecruncuuus spissus, S. Wood. ‘Tab. XVI, fig. 4, a, 4.

Spec. Char. P. testdé spissd, tumidd, globosd, orbiculari, equilaterali ; radiatim
obsoleté costellatd, costis depressis ; umbonibus prominentibus; ared connextis elongato-
trigonatd, profunde sulcata ; margine dentali crassd, dentibus quatuor ad quinque, utroque .
latere transversalibus crassiusculis ; marginibus irregulariter crenulatis.

Shell thick, tumid, globose, orbicular, equilateral, with depressed and obsolete ribs ;
beaks prominent, area of connector broadly triangular, with deep chevron-formed lines ;
dental margin thick, with 4 to 5 teeth on each side, inclining towards the extremities ;
interior margins irregularly crenulated.

Diameter, 13 inch.

Locality. Southampton (Zdwards).

This species, I believe, is not rare; I have seen it only from one locality, and the
specimens appear to be nearly all of the same magnitude, as if the full-grown shell, which
I presume it to be, did not exceed the above dimensions. I have ventured to propose for
this a new specific name, considering the characters to differ from those of any other
species. ‘The nearest to which it approaches is P. globosus of the Bracklesham beds, but
from which it appears to differ in having a more prominent umbo, and that ‘shell has a
more thickened dental area, with fewer teeth.

10. PecruNcULUS TEREBRATULARIS, Lamarck. Tab. XVI, fig. 10.

PECTUNCULUS TEREBRATULARIS. Lamk. Ann. du Mus., t. vi, p. 217, No. 3.
— _ Desh. Coq. foss. des Env. de Par., t. i, p. 221, pl. 35,
figs. 10, 11, 1829.

Spee. Char. “ P. testd orbiculatd, subequilaterd, ventricosd, cordatd, incrassatd, radiatim
sulcatd, sulcis planiusculis decussatis, cardine lato paucidentato ; dentibus laterahbus
striatis.”

Shell orbicular, nearly equilateral, ventricose, heart-shaped, thick, covered with radiating

102 EOCENE MOLLUSCA.

strize or depressed riblets decussated by lines of growth ; hinge-area broad, with few teeth,
lateral denticles striated.

Diameter, 2 inches.

Localities. Herne Bay (Edwards), Upnor (Prestwich).

France: Les environs de Soissons, prés d’Etampes, &c. (Desh. ).

The most distinguishing character in this species is a prominent or rather recurved
umbo, somewhat resembling the beak of a Zeredratula, which, I presume, suggested the
name to Lamarck.

Fig. 10, Tab. XVI, represents a shell that was some years since obligingly given to me
by Professor Morris, and it had the locality-of Ilford attached to it, but that gentleman is
now unable to state from what bed it was derived. It was accompanied by a Cytherea from
the same locality, and this latter species 1 have since obtained from the Woolwich beds
underlying the London Clay, reached in a well-sinking at Romford.. There is therefore
every probability that our specimen came from the same bed at Ilford. Iam unable to
assign this specimen to any species known to me, unless it might perhaps be referred to
brevirostris, but with which it does not. strictly accord. P. polymorphus also much
resembles it.

A shell from the Paris Basin has been Gered and described under the name P. pawei-
dentatus (Desh.), ‘An. sans Vert. du Bass. de Par.,’ t. i, p. 852, pl. 73, f. 16, 17, which
has the locality of Woolwich attached to the description. I have not been able to find
any British specimen entitled to that distinction.

LIMOPSIS, Sassz, 1827.

Gen. Char. Shell orbicular or slightly oblique, convex or lenticular, equivalved, sub-
equilateral, closed; hinge with two slightly curved and slightly unequal series of projecting
and interlocking teeth ; umbones distant; connexus ligamental, bipartite, one portion
inserted in a triangular cavity immediately beneath the umbo; impression of the mantle
entire.

The animal of one species of this genus (ZL. aurita) has lately been obtained in the
seas of North Britain by Mr. Jeffreys, the account of which has been published in the ‘ Ann.
and Mag. Nat. Hist.,’ 1862, and he says ‘‘ the body is of a milk-white colour. The mantle
is open at every part except behind; it has no folds or tubes, and its edges are thickened
and furnished with papilliform glands. The foot is large in proportion to the rest of the
body, and it is shaped like a tobacconist’s knife; it can, in all probability, form a suboval
disc at the central portion, as in Pectunculus.” It so much resembles that genus that
the only distinction on which a separation can be founded is the triangular fossette in the
area for connexus, and this cannot be considered a very important one, as it is present
upon the young shell of Pectunculus decussatus.

BIVALVIA. 103

Some Eocene fossils have been figured and described by MM. Nyst, d’Archiac, and
Bellardi, under the generic name of Sta/agmium, strongly resembling aberrant forms of this
genus ; they differ, however, slightly in the dental area, the central portion being much
broader than in Limopsis, where the triangular fossette has pushed forward the ligamental
connector, so as to diminish materially the dental lme beneath the umbo. In those shells
called Stalagmium there is an absence of the external triangular fossette, the connector
being situated in a linear depression on one side only of the umbo, differing also in that
respect from Pectwnculus, which it otherwise somewhat resembles; the ligamental area is
ridged or furrowed like most of the shells of this family. If these differences be con-
sidered sufficient to constitute.generic distinction, those. shells must. be denominated
Stalagmium, Nyst, as the genus proposed by Messrs. Lea and Conrad is untenable for the
American Eocene fossil, which, as before stated, is a species of Modiola or Orenella.

I. Limopsis cranunata, Lamarck. Tab. XVII, fig. 10, a, 4.

PECTUNCULUS GRANULATUS. Lamk. Aun. du-Mus., t. vi, p: 117, No. 4, and t.-xi, pl. 18,
fig. 6, a, 0.
a —_—. Desh, .Coq. foss. des Env. de Par., t. i, p. 227, pl. 35, figs. 4—
. 6, 1829.
LIMopsIs — Prestwich, Geol. Journ., 1847, p. 404.
— _ J. Sow. in Dixon’s Geol. of Sussex, pp. 93, 170, t. 3, fig. 19.
— = Desh. An. sans Vert. du Bass. de Par., t. i, p. 842, 1859.

Spec. Char. Testa orbiculatdé,; lenticulari, convexa-; subaequilaterali ;. decussatim
striata ; striis longitudinalibus angustioribus granulosis ; cardine recto, umbonibus minimis ;
marginibus obsolete crenulatis.

Shell orbicularly lenticular, convex, slightly inequilateral, striated or radiated and
decussated ; radiations fine and granular; hinge straight, umbones small, depressed ;
margins obsoletely or irregularly crenulated..

Diameter, 4 an inch.

Localities. Bracklesham (Edwards).

France : Grignon, Parnes, Senlis (Deshayes).

This is a rare species in England, and found only at the above locality ; it is said to
be abundant in the Paris Basin.

The surface of this shell is covered with fine, small, radiating striae, which are crossed
or decussated by prominent lines of growth; the conjunction of these two lines causes an
elevation, thus giving a granular surface to the exterior; the shell is nearly lenticular and
equilateral, the diameter being, as near as possible, the same in each direction, though
occasionally it is a trifle in excess in the height. The hinge is furnished with three to
five denticles on one side of the umbo, nearly vertical, and on the other from five to six in
a curving direction, and the interior margin is faintly and somewhat irregularly denticulated.

104 EOCENE MOLLUSCA.

The upper part of the hinge-line is nearly straight, which gives a small shoulder to the
shell on each side. Zrigonocelia granulata, Nyst, ‘Coq. foss. Belg.,’ p. 241, pl. 19, fig. 1,
strongly resembles our-shell by figure and description ; but M. Deshayes, who, I presume,
has examined the Belgian fossil, says it is specifically different. The artist has given
rather too much obliquity to our figure.

Limopsis Belcheri, Adams and Reeve, is said by Mr. Jeffreys, ‘Ann. and Mag. Nat.
Hist.,’ 2nd ser., vol. x, p. 345, Nov., 1862, to be the same as the Eocene species.

2. Limopsis scaLaris, J. Sowerby. Tab. XVII, fig. 9, a, 0.

PECTUNCULUS scaLaRIS. J. Sow. Min. Conch., t. 472, fig. 2.
— — Morris. Catal. Brit. Foss., p. 207, 1854.

Spec. Char. Testa orbiculatd, convead, inequilaterali obliqud ; radiatim costulatd, et
concentricé striata, decussatd ; costulis granulatis, angustis, separatis; curdine obliquo ;
umbonibus parvis ; marginibus crenulatis.

Shell orbicular, convex, ineequilateral, oblique, radiatedly costulated and decussated by
lines of growth; rays rough, subgranular; hinge oblique; umbones small; margins
crenulated. .

Diameter, ths of an inch.

Locality. Barton.

This is an abundant shell at Barton, where the two valves are often found united. The
exterior of this species is prettily ornamented with about twenty-four or twenty-six pro-
minent rays, or rather acutely angular coste, with often an intermediate ray, sometimes
two; these rays are cut or crossed by prominently rounded ridges of growth, which
decussate the surface, and produce a nodulous appearance on the rays, like the exterior of
Pectunculus deletus. ‘The transverse lines between the ribs resemble the steps of a rope-
ladder.” —J. Sowerby. The hinge-margin is furnished with about five to eight prominent
teeth, placed at nearly right angles to the hinge-line on the pedal side, and about nine
to twelve in a curving direction on the other. The interior of the entire margin is
irregularly denticulated, but not at the extreme edge. The triangular fossette in the
area of connexus is large and deep, diverging from the umbo at nearly a right angle.

TRIGONOCGLIA. Deshayes.

Generic Character. Shell equivalve, generally small, inequilateral ; more or less trigo-
nular or deltoidal; pedi-lateral margin rounded, siphoni-lateral angular; umbones pro-
minent, ventral margin smooth ; hinge-line divergent, with sharp and generally angular

BIVALVIA. 105

and prominent denticles, divided into two portions; connexus ligamental, placed in a
triangular fossette ; two adductor-muscles ; impression of mantle without a sinus.

The connector being situated entirely on the outside of the dental apparatus, concen-
trated in a triangular cavity and opening the valves by contraction, is a sufficient character
to entitle these shells to be placed in a distinct generic position. This triangular fossette
bears a resemblance to that upon Zimopsis, but there is no extended area or bipartite
division of the connector, as in that genus.

M. Nyst proposed the name Zrigonocelia for those bivalves which resembled Pectun-
culus, but differed in the disposition of the connector, as before remarked. TZ'rigonocelia,
therefore, from want of priority, had lapsed into a synonym. M. Deshayes has employed
the above name for his genus, as the type species had been called Zrigonocelia by M. Nyst.

The present genus is an emanation from Zimopsis, differmg from it by the loss of the
expanded ligamental area, approaching closely to Zeda in the form of the shell. The
animal is at present unknown, but from its pointed siphonal region it probably possessed
incipient siphons.

A few species only of this genus have been described; six of these are from the Paris
Basin, and one has been figured by Mr. Lea from the Eocene deposits of America ; these,
with the British species, are all confined to the older Tertiaries. The animals appear to
have been capable of firmly closing their valves ; they have large and well-marked impres-
sions of the adductors.

1. Triconocarta peLtoipDEA? Lamarck. Tab. XIX, fig. 11, a—e.

Nucuza peLtorpEA? Lamk. Ann. du Mus,, t. vi, p. 126, and t. ix, pl. 18, fig. 5.
— _ J. Sowerby. Min. Conch., t. 554, fig. 1.
Limopsis DELTOIDEA ? D’Orbd. Prod. de Paléont., t. ii, p. 389, No. 1019.
LEDA DELTOIDEA. Morris. Catal. Brit. Foss., p. 205, 1854.
TRIGONOCGLIA DELTOIDEA? Desh. An. sans Vert. du Bass. de Par., t. i, p. 840, 1858.

Spec. Char. T. testé trigoné vel deltoidea, tumidd, crassiusculd, subequilateralt, con-
’ centricé striata ; pedi-regione rotundatd, obsoleté radiata ; siphoni-regione angulatd, et
carinatd ; umbonibus magnis prominentibus ; cardine arcuato, dentibus 5 vel 6 utroque
latere ; fossuld connexiis profundd, triangulari.

Shell trigonal, tumid, rather thick, nearly equilateral ; concentrically striated ; pedal
region rounded and obsoletely rayed ; stphonal region angulated and keeled; beaks large
and prominent ; hinge-line curved, furnished with 5 or 6 denticles on each side ; depres-
sion for connector deep and triangular.

Length, ths inch ; heaght, ith inch.

Localities. Barton (Hdwards), Hordle (S. Wood), Shapley Heath (Morris).

106 EOCENE MOLLUSCA.

This species appears to be restricted to the uppermost deposits; I have not seen it
from below the Barton beds. It is not rare, though by no means so abundant as the
Paris Basin shell. On comparing the British fossil with the French species, the following
differences may be observed. Our shell is shorter, more elevated, and more regularly
ribbed in the direction of the lines of growth; the angle on the siphonal region is sharper
and more-distinct, and there are only small, fine, and very faint rays upon the edge of the
pedal region, whereas in the French shell these rays are few, large, sharp, and very pro-
minent. The exterior of our shell has faint radiating lines, only perceptible in very perfect
specimens, and by the assistance of a magnifier; they are most distinct on the siphonal
region, particularly beyond the angular slope near the siphoni-lateral margin. ‘The number
of denticles are fewer in our shell than in the French specimens. It. may be called var.
delta-formis. 4

2. TRIGONOCELIA CANCELLATA, Deshayes. Tab. XIX, fig. 12.

TRIGONOC@LIA CANCELLATA. Desh, An. sans Vert. du Bass. ‘de Par., t. i, p. 838, pl. 64,
figs. 3135, 1860.

Spec. Char. P. “ testd transversim trigond, inflata, subequilateral, antice obtusd, postice
acute angulatd, striis longitudinalibus, transversalibusque, eleganter decussatd, ad latus.anti-
cum longitudinalibus, proeminentioribus, distantioribus ; latere postico plano, ovato, angulo,
acuto, aliquantisper proeminenti separato, liris tenuibus distantibus ornato ; cardine brevt,
angusto, paucidentato ; dentibus minimis, sepius complicatis, fossuld lgamenti satis lata,
regulariter triangular.” —Desh. .

Shell elongately trigonular, slightly inflated ; subequilateral; pedal region the larger,
somewhat inflated; pedilateral margin rounded; siphonal region slightly compressed,
angular, with pointed termination; exterior radiated and decussated by prominent and
regular lines of growth ; hinge-area small,. denticles. few ; depression for connexus broadly
triangular and shallow.

Length, + an inch.

Localities. Wuntingbridge.

France: Parnes, Damery-Auvers,-Acy, Mary, Caumont, Crouy, La Ferté-
sous-Jouare, Le Fayel (Deshayes).

A single specimen only of this species has been obtained by Mr.,Edwards, and that
unfortunately is not quite perfect ; a part of the hinge-area has been destroyed, but the
exterior and general contour of the shell correspond with the French species, and it may
fairly remain with the above name for the present. It is quite distinct from our de/totdea.

BIVALVIA. 107

MUG eAnct amarok

Generic Character. Shell ovately trigonal or nut-shaped, smooth, or occasionally
sculptured ; nacreous, inside iridescent ; siphonal region short or truncated ; the umbones
never prominent; hinge with a row of more or less numerous angular and elevated inter-
locking teeth ; connexus cartilaginous ; palleal line simple.

Animal of the shape of the shell; margins of the mantle disconnected all round ; foot
large, capable of being expanded into a disc, and ornamented with fimbriated edges.

The peculiarity of this genus consists in having the larger portion of the shell on the
pedal side, and the umbo pointing in the opposite direction, an arrangement contrary to
that which prevails in the generality of bivalves, and also in having the spoon-shaped projec-
tion within the hinge-margin, on which is placed the cartilaginous connector on the pedal side
of the umbo. The hinge-line forms nearly a right angle, but this diverges into an obtuse
one im the aberrant species, where an extension of the shell, on the verge of the genus,
approaches the ovate or elongated form of Leda.

The animal of this genus, the inhabitant of the shell which is the type, is said not to
have any siphons, and that the margins of the mantle are disconnected. In the approxi-
mating genus Leda, the mantle in the siphonal region is connected so as to form two
distinct tubes, which are capable of considerable exsertile extension. ‘The animal of Nucula
proper has the mantle open all round; but in those species which have an extension on
the siphonal side approaching Zeda, it will probably be found that the margins of the
‘mantle in the siphonal region are partly connected, so as to separate the incoming from
the outgoing current. .

In this genus the greater number of the fossil species have the interior or ventral
margins of the shells ornamented with crenulations. ‘These crenulations are found in those
species only in which the exterior of the shell is covered with radiating lines ; they are
apparently due to the fimbriated edges of the mantle, and do not extend to the edges
of the dorsal margins, even where the area of dentition is limited. The ventral margins of
the mantle in JV. nucleus are said to be plain; but I imagine they must be very finely fim-
briated, in order to deposit the elevated layers of shelly matter which produce the radia-
tions. ‘These rays are most conspicuous upon the under surface, which is sometimes covered
over with a coating of enamel-like material, so as to obliterate or at least to obscure the rays ;
but when the margins are crenulated, I presume they will always be more or less visible.

The shells of the species which have the margins smooth will be entirely free from
radiating striae, and the edges of the mantle of those animals are probably quite plain.

The shells in the living state are covered with an epidermis, remains of which may be
occasionally observed upon specimens of the Eocene deposits. Some have their radiations
strongly decussated by elevated lines of growth ; a few species also have a peculiar ornament
in a zigzag form, and for these a sub-genus has been proposed, under the name Aei/a,

15

108 EOCENE MOLLUSCA.

by Messrs. Adams. I have not seen this kind of sculpture upon any Eocene fossils. In
this genus it is often difficult to determine, in descriptions, which part is intended for the
“anterior,” as that term is applied sometimes to the shorter, at others to the longer
division of the shell.

It has been generally supposed that the species of Nwcula are well defined and easily
determined, but I am sorry to say, they have not appeared so to me. The Eocene species
have given me more trouble in their assignment than those of almost any other genus,
and the result is not at all satisfactory to myself; it will be fortunate for me if I be the
only one of that opinion. The Eocene shells of this genus found in England, and here
illustrated, present a great variety of forms, most of which I have considered as entitled
to specific distinction ; it is however possible, that with a larger amount of materials,
some of these lines of division might disappear.

1. Nucuna ampia, Hdwards, MS. Tab. XVIII, fig. 5, a, 4, var. fig. 6, a, 4.

Spec. Char. WN. testa transversd, ovato-subtrigonuld vel nuciformi, ampla, tumidiusculd,
crassa, levigatd ; pedi-regione latiore ; ano-regione paulo attenuata, rotundatd ; margine
dorsali convexiusculd ; margine ventrali plus convead ; lunulé elongato-lanceolata ; dentibus
ad apicem gradatim minutis ; marginibus crenulatis.

Shell transverse, ovately trigonular or nut-shaped, broad, somewhat tumid, thick,
smooth ; pedal region the broader; anal region slightly projecting and rounded; dorsal
margin slightly convex, ventral margin more rounded; lunule elongated; denticles
diminishing towards the apex ; margins crenulated.

Length, } an inch.

Locality. Barton (Hdwards).

This species, I believe, is not very rare. Its peculiar or specific distinction is the
roundedly ovate form, which appears to be more so than in any other species I have seen. _
The anal region is much rounded, and the dental area on that side short, by which is
given a greater convexity to the ventral margin. It has an elongated indistinct lunule or
dorsal depression, with a slightly elevated corselet surrounded by a depression; it bears
some resemblance to JV. /unulata, Nyst, but it appears to differ from that species in having
both dorsal and ventral margins more curved, and it has not so distinct and prominent a
corselet as that species. The mterior is sometimes much thickened, and the adductor
marks are deep; there is also an elongated impression of the pedal muscle near the oral
adductor, beneath the dental margin, and generally in thickened specimens an upright
visceral (?) impression. Fig. 6, a, 4, in same plate, represents a specimen in Mr. Edwards’s
cabinet with the MS. name of covtigua; in this there is a slight difference in the contour,
and in the anal region, but I think it is scarcely entitled to specific distinction. I have
therefore considered it only as a variety of the above species.

BIVALVIA. 109

2. Nucuna sBisuteata, J. Sowerby. ‘Tab. XVIII, fig. 13, a—c.

Nucuta BisuLcaTa. J. Sow., in Dixon’s Geol. of Sussex, pp. 93, 170, t. 2. fig. 13. 1850.
— — Morris. Catal. Brit. Foss., p. 217, 1854.

Spec. Char. N. testdé ovato-subtrigond, elongata, crassd, levigatd ; pedi-regione
ellipticd, longiore et altiore ; siphoni-regione angulatd, subproducté, compressiusculd ; lunuld
elongato-lanceolaté, bisulcatd ; ano ovato, in medio prominente ; dentibus ad apicem gradatim
minutissimis ; marginibus integris.

Shell ovately sub-trigonular, elongated, thick, compressed, smooth; pedal region
elliptical, margin ovately rounded ; siphoni-lateral margin angulated, compressed, and
slightly produced; Junule elongately lanceolate, with a central ridge; anal region ovate,
prominent in the centre; teeth diminishing towards the umbo, ventral margin smooth.

Length, \} inch; heaght, 1 inch.

Localities. Barton, Bracklesham.

Specimens of this species are not very abundant, and have, I believe, been as yet only
found at the above localities.

The shell is nearly smooth, with the exception of distinct lines of growth. ‘I'he dorsal
margin has a sort of flattened space (lunule), with a central elevation or ridge, on each
side of which is a depression or furrow, giving a sinuation to the pedi-lateral margin, and
to this peculiarity of character the species owes its name. ‘The muscle-marks are both
deeply impressed, the anal one more especially so; it is of an elongated form, pointed
towards the umbo, and there is also an impression in the umbonal region, probably left by
the retractors of the foot. The teeth are not numerous, about a dozen on the pedal side,
and half that number on the other. The shell in the living state was probably covered
with a thick epidermis; traces of this may be seen on many specimens. The nearest
approach to this is a recent species, V. Cumingii, from the Indian Archipelago, but
from which it differs, according to description, in not having the lunule with a bipartite
division.

3. Nucuta Bowersankil, J. Sowerby. Tab. XVIII, fig. f£ 14, a, 3d.

Nucuta BowerBankul. J. Sow. Geol. Trans., 2nd series, vol. v, t. 8, fig. 11, 1834.
— _ Prestwich. Geol. Joury., 1847, p. 405.
— = Morris. Cat. Brit. Foss., p. 217, 1854.

Spec. Char. NV. testé late ovatd, subtrigond, valdé inequilaterali, convexd, radiatim
striata ; striis depressis, latis, approximatis ; siphoni-regione oblique truncata; lunuld
elongato-lanceslata vix perspicud ; marginibus crenulatis.

“ Elliptical, convex, smooth externally, striated within ; anterior (?) extremity obliquely

110 ‘ EOCENE MOLLUSCA.

truncated ; the slope filled by a large, pointed, nearly flat lunette, edge toothed ; impression
of the abductor muscles shallow.” —(J. Sowerby).

Length, \ inch ; height, 2ths of an inch.

Localities. Uighgate, Potter’s Bar (Wetherell); Haverstock Hill (Edwards).

This species was apparently covered by a thick epidermis, and the umbones have been
very much eroded. ‘The anal region or corselet is well marked and flat, with a slight rise
in the centre, and covered only by lines of growth. The surface of the shell is smooth to
the unassisted eye, but it is covered with narrow, deep, radiating lines, making the rays
broad and flat, and there is a depression on the dorsal portion of the pedal region irre-
spective of the lanceolated lunule, as if the ventral margins were capable of being widely
separated. The species appears to be confined to the London Basin.

The interior cast of a shell of this genus is figured and described in the ‘'Trans. of
the Geol. Soc.,’ 2nd series, vol. v, pl. 24, fig. 5, under the name JV. Baboensis, and is
said by the author to “nearly resemble V. Bowerbankii, but not truncated or pointed
below the lunette.” This specimen came from Baboo Hill in Cutch, and it is in that
easterly direction that we might look, I think, for shells probably identical with some
of our own Eocene fossils, but I fear it is not possible to certify a species by the cast alone.
There is also the cast of a species in this genus found in the Eocene Formation, between
Holyport and Birfield; the specimen was deposited in the Museum of the Geological
Society, by the late Mr. Warburton (marked No. 17839), and has a somewhat similar
form, but it presents the same difficulty for determination, and I am unable to assign
it to any species; these various casts do not show whether the inner margins were
furnished with crenulations.

4. Nucuna carpioipEs, Hdwards, MS. ‘Tab. XIX, fig. 8.

A single specimen from Pegwell Bay, in the cabinet of Mr. Edwards, has the above
name attached to it, and it appears to belong to a distinct species ; but it is very imper-
fectly preserved, and I am unable to describe its true characters. The shell is externally
rayed with distinct and well-marked striz or riblets, and the inner margin is crenulated.
Its present name must be considered provisional.

5. Nucuna compressa, J. Sowerby. ‘Tab. XIX, fig. 5.

NucuLa compressa. J. Sow. Geol. Trans., vol. v, 2nd ser., p. 136, pl. 8, fig. 14, 1834.
— _ Prestwich. Geol. Journ., 1847, p. 405.
— — Morris. Catal. Brit. Foss., p. 217, 1854.

BIVALVIA. 111

Spec. Char. WN. testa, elongato-ovatd, turgidd, tumidd, inequilaterali ; levigatd, glabra,
margine dorsali subrecta, pedi-regione ovatd ; siphoni-regione, prelongd, subrostrata ; mar-
gine ventrali converd ; lunuld viv conspicud ; apicibus depressis ; marginibus integris.

Shell elongately ovate, inflated, inequilateral, smooth and glossy; dorsal margin
nearly straight; ventral margin convex; pedal region large, ovate; siphonal region
obtusely pointed ; lunule inconspicuous ; beaks depressed ; margins smooth.

Length, xths of an inch; Aezght, §ths of an inch.

Locality. Wampstead Heath (Wetherell); Potter’s Bar, and Highgate (Edwards).

The peculiar distinction is the pointed or subrostrated form of the siphonal region,
where it is slightly compressed, from which I presume it received its name, as the shell is
otherwise rather tumid.

6, Nucuxa consors, 8S. Wood. Tab. XIX, fig. 7, a, 0.

Nucuta stmiLis. J. Sow. Min. Conch., vol. ii, p. 207, t. 192, figs. 3, 4, 1819.

Spec. Char. WV. testd obovatd, transversd, subtrigonuld, turgidd, valdé inequilaterah,
obsolete radiata, aliquantisper striis transversis decussatd ; pedi-regione prolongd, obtusa ;
siphoni-regione rotundate truncatd ; margine ventrali convexd ; lunuld viv distinctd ; ano
ovato in medio prominenti ; marginibus crenulatis.

Shell transverse, obtusely ovate, roundedly trigonal, turgid, very inequilateral, obsoletely
rayed, slightly decussated by lines of growth; pedilateral margin obtusely or roundedly
angulated ; dorsal and ventral margins convex ; lunule indistinct ; anal region slightly
prominent ; internal margins crenulated.

Length, } an inch; height, sths of an inch.

Locality. Uighgate (Wetherell).

Many specimens of this species are in the cabinet of Mr. Wetherell; but they are
seldom in good condition, the greater number of them being merely casts.

Professor Morris, in his ‘Catalogue of British Fossils,’ has rejected figs. 3 and 4,
t. 192, ‘ Min. Conch.,’ from being identical with the Barton species figured upon the same
plate, and Mr. Sowerby says, at p. 208, he is doubtful whether fig. 4 ought not to be
considered a distinct species, or at least a distinct variety, implying thereby a doubt as to
the propriety of admitting it under the name of szmz/is. I have, therefore, given it a new
specific name with more confidence, having the support of the above two opinions. It
resembles in many of its characters one or two species from the Middle Eocene, but with
none does it appear to be truly identical. It has no distinctly marked lunule. There is
a prominent anal region surrounded by a depression, and in those specimens which are
best preserved the radiating striz are very distinct, decussated by lines of growth. The
two valves are most commonly united, and many of them have been perforated by a
zoophagous feeder.

112 EOCENE MOLLUSCA.

Fig. 3 in ‘ Min. Conch.’ is more angulated than fig. 4, but I think they both belong
to the same species, as there is considerable variation in the outline among Mr. Wetherell’s
specimens.

7. N. curvata, Hdwards, MS. Tab. XVIII, fig. 12, a, 4.

Spec. Char. NV. testa transversd, ovato-subtrigonuld, tumidiusculd, crassiusculd, obsoleté
radiata, radiis vel striis tenuissimis ; valde inequilaterali ; pedi-regione angulata, producté ;
ano-regione brevi, in medio prominenti ; margine dorsali sub-recté ; margine ventrali con-
veatuscula ; lunuld lanceolata vix conspicud ; marginibus crenulatis.

Shell transverse, ovately trigonular, slightly tumid, and moderately thick ; obsoletely
radiated with very fine lines or striz; pedal region produced and angulated; anal region
short, and rather prominent in the centre; dorsal margin nearly straight, ventral margin
curved ; lunule scarcely conspicuous, margins crenulated.

Length, sths of an inch.

Locality. Clarendon (Hdwards).

This species is at present very rare. It somewhat resembles JV. sphenoides, but it
is comparatively longer; it is more produced and angular at the pedilateral margin, and
it is less tumid than the Upper Eocene shell.

Two or three specimens in Mr. Prestwich’s cabinet, obtained from a boring for an
Artesian well at Southampton, appear to belong to this species; the age of the bed from
which they came is not stated.

8. Nucuna Dixoni, Hdwards, MS. Tab. XVIII, fig. 7, a—e.

Nucuta stmitts. J. Sow., in Dixon’s Geol. of Suss., p. 93, t. 2, fig. 7, 1850.

Spec. Char. N. testé ovato-subtrigonuld, turgidd, lavigatd, valdé inequilateralt,
convexd ; siphoni-regione truncaté ; lunuld obtuse angulata vie perspicud ; cardine crassa,
dentibus magnis ; fossuld conneais elongaté ; marginibus crenulatis.

Shell ovately triangular, somewhat tumid, smooth, convex, very inequilateral ; stphonal
region truncated; lunule and corselet not very distinctly defined ; teeth thick and broad
towards the connector, margins crenulated.

Length, iths of an inch; height, tths of an inch.

Localities. Bracklesham, Stubbington, Whitecliff Bay (Zdwards).

This species is by no means rare at Bracklesham. It appears to differ from s¢mz/is in
being more tumid and less angular, and rather more elongated, and it has not the projecting
pointedness at the basal margin of the siphonal region which is characteristic of that species.
‘The exterior is more convex, and the radiating lines are less distinct in this than they are

BIVALVIA. 113

in similis, which is its nearest relative. It bears a strong resemblance to NV. margaritacea
of Nyst, ‘Coq. Foss. Belg.” p. 229, pl. xvii, fig. 9, a, 6, but the dorsal margin of that
figure is rather more curved. NV. margaritacea, Goldf., ‘Petr. Germ.,’ vol. i, p. 158. t.
125, fig. 21, a—d, also much resembles it.

Some specimens in Mr. Edwards’s cabinet from the same locality have attached to them
the MS. names of guadrans,'Vab. XVIII, fig. 8, a, 4, and planiuscula, same plate, fig. 9 ;
they differ im outward form, as those names indicate, but I think they are varieties of the
above. It is possible they may prove to be distinct.

9. Nucuta Heaponensis, Forbes, MS. ‘Tab. XVIII, fig. 3, a, 4.

Nucuta Heaponensis. Morris. Mem. Geol. Surv., p. 156, pl. 6, figs. 12, 12, a, 6, 1856.
= = Id. Catal. Brit. Foss., p. 218, 1854.

Spec. Char. “ Testa ovato-transversda, depressd, levi, latere antico brevi, subproducto,
margine arcuato, posticé angusto, margine ventrali subarcuato, intus crenulato ; lunuld
prominuld, sulco perspicuo circumdata.”

« An ovately transverse and somewhat depressed shell, with the anterior margin short
and slightly produced, the posterior extremity narrowed, the ventral margin arched and
internally very finely crenulated ; the lunule prominent, and surrounded by a conspicuous
furrow.” —Morris.

Length, *ths of an inch.

Localities. Colwell Bay, Headon Hill (Morris and Edwards), Hordwell (S. Wood),

This species has been separated from semlis by the late Edward Forbes; it has also
been considered by Mr. Morris as distinct, and I readily acquiesce in the separation.
Specimens are not particularly rare, and are found often in a very perfect state of preser-
vation. It somewhat resembles in outline V. Dizoni, but it is asmaller species ; the siphonal
region is shorter, and the basal extremity on that side is more rounded, and it appears also
to be a thicker shell. In the ‘Catal. Brit. Foss.,’ p. 218, 1854, Mucula similis, Wood, is
given as a synonym to this species, but I have not been able to find the reference.

10. Nucuua tissa, Hdwards, MS. Tab. XVIII, fig. 4, a, 3d.

Spec. Char. NV. testé elongato-ovatd, tenui, levi, glabra, compressiusculd, inequilateral ;
pedi-regione latiore, ovata ; siphoni-regione oblique truncata, subrostrata ; marginibus dorsali
et ventrali convewis ; lunuld lanceolato-elongatd, depressa ; ano cordiformi ; dentibus ad apicem
gradatim minutissimis ; marginibus integris.

Shell elongately ovate, thin, smooth, and glossy, slightly compressed, ineiuilaterst:;
pedal-region the wider and ovately rounded; siphonal region obliquely truncated ; dorsal

114 EOCENE MOLLUSCA.

and ventral margins curved; lunule elongate, distinct, and rather depressed ; anal region
heartshaped ; teeth small near the beak; margins smooth.

Length, } an inch ; heaght, sths of an inch.

Locahties. Highcliff, Barton, Brockenhurst, Hordwell (Hdwards). _

Although a thin and delicate shell, it has been obtained by Mr. Edwards in great
abundance. The exterior is smooth and glossy, with a few concentric ridges or obtuse
lines of growth. The interior has a strong nacreous lustre, with an enamelled exterior.
The hinge-line is narrow ; it has about a dozen denticles on the pedal side, with scarcely
half that number on the other, and the support for cartilage is simple, somewhat elongated,
projecting inwardly at an angle of 45° to the dorsal margin. ‘There is a deep depression
(lunule P) on the pedal region, producing a sharp elevation to the dorsal margin, with a
faint depression on the siphonal or anal region, but not very well defined. The extremity
of the siphoni-lateral margin is rather short and generally more or less pointed or subro-
strated ; this gives a considerable convexity to the ventral margin in the normal form. The
shell is thin, and the oral muscle scarcely visible, but the anal one is large and well
impressed.

There are, I think, three varieties of this species; at least, there are three different
forms, which I have referred to the above name, presenting as they do considerable
difference in outline, but not, I think, sufficient to entitle them to different specific
positions. Tab. XX, fig. 1, a, 4, c.

ll. Nucuna minor, Deshayes. Tab. XVIII, fig. 10.
Nucuta minor. Desh. An. sans Vert. du Bass. de Par., t. i, p. 823, pl. 64, figs. 17—20, 1860.

Spec. Char. N. “ testé minimd, ovato-trigond, turgidula, valdé inequilaterali ; posticé
transversim truncatd ; superné declivi; anticé attenuata, transversim tenui-sulcatd ; sulcis
anticé paulo undulatis ; lunuld nulla ; ano plano, non circumscripto ; cardine angusto, pauct
dentato ; dentibus angustis distantibus ; fossuld minimd, brevi, angustd ; marginibus sublente
minutissime crenulatis.”—Desh.

Shell small, ovately trigonular, slightly tumid, siphonal region short, obliquely trun-
cated ; pedal region ovately rounded ; concentrically ridged or sulcated ; ridges slightly
irregular ; no lunule; anal region smooth, convex in the centre; dental margin narrow,
teeth few and small; margins crenulated.

Length, ith of an inch.

Localities. Bracklesham (Edwards).

France. Le Guépelle, Chéry-Chartreuve, Ver, Beauval, Houdan (Deshayes).

The figure was taken from a unique and perfect specimen in the cabinet of Mr.
Edwards.

So far as I am able to determine from figure and description in the work above
referred to, I think our little shell may be considered as identical with the Paris Basin

BIVALVIA. 115

species. The only difference I can perceive between the English and the French fossils is
in the contour of the specimens ; ours being apparently a little longer and rather more
rounded on the pedilateral margin. Our shell is ridged concentrically, and these ridges
are rather broad, and occasionally inosculate or undulate, like those spoken of by M.
Deshayes, “ quelquefois un peu onduleux vers l’extremité anterieure.”

A recent species from the Straits of Malacca, figured and described by Mr. Hanley
under the name of JV. marmorea (‘ Monog. of Nuculide,’ p. 48, pl. v, fig. 145), appears,
from representation, to be its nearest relative.

72. Nucuna nupata, S. Wood. Tab. XX, fig. 4, a, é.

Spec. Char. NN. testdé ovato-trigond, transversd, tenui, valdé inequilaterali, laevigata ;
margine dorsali vie incurvatd, margine ventrali convewiusculd ; pedi-regione ovato-rotundata ;
lunula inconspicud ; ano depresso, ovato ; marginibus integris.

Shell ovately trigonal, transverse, thin, smooth, very inequilateral ; dorsal margin nearly
straight, ventral margin slightly curved ; pedal side roundedly ovate ; lunule inconspicuous ;
_anal region depressed ; margins smooth.

Length, 3rd of an inch.

Locality. Headon Hill (8S. Wood). Brockenhurst? (Hdwards).

A few specimens of this species were found by myself many years ago, and I have
considered them as entitled to the rank of a distinct species, in consequence of the ventral
margins being quite free from denticulations, and of the outward form differing from that
of any other smooth-margined species.

The shell in its contour much resembles WV. //cadonensis, but it is a little longer,
more rounded, and less tumid than m that species, and it is distinguished by the
difference of margin. It bears, also, some resemblance to JV. “ssa, but it differs in two or
three characters; in the latter species the anal or siphonal side is more pointed or
acutely angular, the dental area shorter, and the ventral margin more rounded than in J.
nudata; 1 NV. lissa, there is also a more distinct sinus or lunule below the dorsal
edge on the pedal side, and the shell is comparatively longer and thinner. The angle
formed by the two dental lines in this species is very little more than a right angle, but
in JV. Uissa that angle is very obtuse.

13. Nucuna rraionca, Edwards, MS. Tab. XIX, fig. 4 a, 3.

Spec. Char. N. testé elongato-ovatd, prelongd, levigata, tenui, conveaiusculd, inequi-
laterali ; pedi-regione ovato-rotundata ; siphoni-regione obliqué truncata ; lunuld clongato-
16

116 EOCENE MOLLUSCA.

lanceolatd, bisulcatd ; ano ovato, obtusé circumdato, in medio prominenti ; apicibus depressis,
approximatis ; marginibus integris.

Shell elongately ovate, smooth, thin, and slightly convex or tumid, inequilateral ;
pedal region ovately rounded ; siphonal region obliquely truncated, or very obtusely
rostrated; lunule elongated with a central elevation or ridge; anal region ovate and
centrally elevated ; beaks depressed ; margins smooth. |

Length, \ inch; height, 5 an inch.

Localities. Barton (Edwards).

This species has considerable affinity with WV. dzswleata. It appears to differ in being
of a more elongated form, and in having the siphonal region more inflated; the whole
shell appears to be more regularly convex, and the concentric lines or lines of growth are
more distinct than they are upon JV. dzsulcata.

This shell, perhaps, was not covered with a very thick epidermis, as there are no
remains of it upon any of the specimens I have seen, and the beaks are not eroded.

14. Nucuta pratoneata, S. Wood. Tab. XIX, fig. 1 a, 6.

Spec. Char. NN. testa ovato-clongatd, prelongatd, tenui, levigatd, converiusculd, ©
inequilaterali ; pedi-regione ovato-rotundata ; siphoni-regione brevi, subangulaté ; lunuld
lanceolata, bisulcatéd; ano ovato, circumdato, in medio prominenti; apicibus depressis,
approximatis ; marginibus crenulatis.

Shell ovately elongate, thin, smooth, and slightly tumid, inquilateral; pedal region
roundedly ovate ; siphonal side short and slightly angulated; lunule elongate, with double
shallow depression ; corselet slightly prominent in the middle; beaks depressed ; margins
crenulated.

Longest diameter, 1 inch nearly.

Locality. Bracklesham (Hdwards).

Only two or three specimens of this species have come under my observation ; they
somewhat resemble in form JV. prelonga, but the crenulated margin will distinguish them,
and there is a difference, also, in their comparative lengths. This shell seems, also, to be
more iridescent than JV. pre/onga, and rather more deep or tumid.

Two other specimens from the same locality, in Mr. Hdwards’s cabinet, have a somewhat
similar outline, but they have not the basal portion of the anal region quite so much
extended or angular; they appear, also, to have a more distinct lunule and corselet than
the one figured (prelongata) ; and these depressions (lunule and corselet) are divided by
a small central ridge, which I do not perceive in our figured specimens. I am, however,

unwilling to separate them, as they otherwise correspond, and future observations must
determine whether they be the same or different.

BIVALVIA. 117

15. Nucura proava, S. Wood. Tab. XX, fig. 3, a, 6.

Spec. Char. N. testa transversd, ovato-oblongd, turgiduld, levigatd, valde inequilaterali ;
umbonibus minimis, terminalibus ; lunulé nullé; ano brevi, ovato, in medio prominulo ;
margine dorsali conveaiusculdé ; margine ventrali curvatd; dentibus ad apicem gradatin
minutissimis ; marginibus integris.

Shell transverse, ovately oblong, slightly tumid, smooth, and very inequilateral ; beaks
small, depressed, terminal; no lunule; anal region short, distinct, and slightly prominent
in the centre; dorsal and ventral margins slightly curved, the latter rather the more so ;
teeth not very close, diminishing towards the umbo; margins smooth.

Length, sths of an inch; height, } an inch.

Locality. Near Bishopstone, Herne Bay.

A single specimen of this species is in the Museum in Jermyn Street, and the officers
of that establishment have kindly permitted me to have it figured. It is the only one
that I have seen.

The nearest approach to this shell that I know is NV. /evigata of the Coralline Crag,
but it differs from that species in outline; it is less curved in the ventral margin, and the
anal region is shorter. In form it somewhat resembles V. Bowerbankit, but that species
has the inner margins crenulated. The denticles are not very numerous on the pedal
side; they are hidden by the matrix on the margin of the anal region ; so, also, is the
place for connexus.

16. Nucuna prorracta, Hdwards, MS. Tab. XVIII, fig. 15.

Spec. Char. N. testd transversd, elongato-ovatd, levigatd, tenui, tumidiusculd, valde
inaquilaterali ; pedi-regione ovato-subattenuatd ; siphoni-regioni brevi, oblique truncaté vel
anguatd ; lunuld parvd, lanceolaté, unisulcatdé ; ano ovato, viv conspicuo ; marginibus
crenulatis,

Shell transverse, elongately oval, smooth, thin, slightly tumid, and very inequilateral ;
pedal region obtusely pointed ; siphonal region short, obliquely truncated or angulated ;
Junule small, plain, elongated, and flat; corselet ill-defined; margins crenulated.

Length, ths of an inch; height, &ths of an inch.

Locality. Bracklesham (dwards).

A single specimen in Mr. Edwards’s cabinet, from which the figure above referred to
was taken, appears to be distinct, and I have, in consequence, adopted the MS. name

118 EOCENE MOLLUSCA.

attached to it. The nearest approach to this in outward form is WV. sericea, Tab. XIX,
fig. 3, but that is a smaller shell, with the dorsal margin less convex and the ventral
margin less curved than in this species; this shell is more ovate or less wedge-shaped,
with the terminal portion of the siphoni-lateral margin more pointed, and the siphonal
region slightly compressed. It resembles in outline W. disulcata, but that shell has a
smooth margin.

17. Nucuxa stmris, J. Sowerby. Tab. XVIII, fig. 11 a—e.

Nucuta stmiuis. J. Sow. Min. Conch., t. 192, fig. 10, 1819.
a — Morris. Catal. Brit. Foss., p. 218, 1854.
— TRIGONA. J. Sow. Min. Conch., t. 192, fig. 5, 1819.
ARCA NUCLEUS. Solander, in Brand. Foss. Hanton., p. 40, t. 8, fig. 101, i766.

Spec. Char. NV. testa ovato-trigond, crassa, sub-compressd, levigatd aut obsoleté radiata,
concentrice irregulariter lineata ; siphoni-regione brevissimd, truncata, ad basim eversd,
sub-acuminata ; lunulé anoque angulo obtuso ; dentibus numerosis ; marginibus crenulatis.

Shell ovately trigonal, thick, slightly compressed, smooth, or indistinctly radiated, and
irregularly furrowed concentrically; siphonal region short, truncate, with the basal
termination everted and somewhat pointed; lunule and corselet indistinctly defined ;
denticles numerous, rather thin and compressed ; margin crenulated.

Length, 1 inch ; height, sths of an inch.

Locality. Barton.

Considerable difficulty exists with regard to this species, of which numerous specimens
are found at Barton. It is, I believe, the true Arca nucleus of Solander, a specimen from
his collection being still in the British Museum. J. ¢rzgona, Sowerby, is probably only the
young, or, at most, a variety of this species; and as it is so marked upon Mr. Edwards’s
tablet, I am pleased to find he is of the same opinion. There is a French shell figured by
M. Deshayes, WV. mixta, ‘ An. sans vert. du Bassin de Par.,’ t. 1, p. 819, pl. 64, figs. 1—4,
which very closely resembles it; but he says the distinctions between the specimens
themselves are evident and permanent, and such as will justify specific separation. Our
shell is a handsome one, and is of considerable solidity, rather flat or compressed; it is
readily distinguished from all other species excepting WV. mixta. The distinguishing
character is an extension or pointedness at the extreme basal portion of the siphonal
region, and the hinge also is somewhat peculiar, often presenting broad teeth near the
umbo.

BIVALVIA. 119

18. Nucuxa spHENoIDES, Hdwards, MS. Tab. XVIII, fig. 2, and Tab. XIX, fig. 2 a, 6.

Spec. Char. NN. testd minutd, irregulatim trigond vel sphenoided, tumidd, levissimd,
politad ; pedi-regione ovato-angulatd ; siphoni-regione brevissimd, truncata ; ano distincto,
circumdato, in medio prominent ; lunuld elongata, depressd, divisd ; margine dorsali sub-
arcuatd ; margine ventral convexd ; marginibus crenulatis.

Shell small, roundedly triangular or wedge-shaped, tumid, smooth, and glossy ; pedal
region obtusely pointed; siphonal region very short, with a prominent anal corselet
surrounded by a depression ; ventral margin very convex, with the edges crenulated.

Length, 3ths of an inch.

Localities. Hempstead, Brook? (Hdwards).

A few specimens of an elegant little species enrich the cabinet of Mr. Edwards, and
there is attached to them the above name in MS. ‘They very closely resemble a species in
the Paris Basin figured and described by M. Deshayes under the name of WV. Greppini,
especially the specimen represented by fig. 2, Tab. XIX, and when the specimens them-
selves are compared they may possibly prove to belong to the same species, but I have
not the means of doing this. There is, however, an apparent difference, which I may here
point out. Our shell has the dorsal margin less curved, while the ventral margin is more
so, than is represented in the figure of JV. Greppini, Desh., p. 882, pl. lxiv, figs. 13—16 ;
and it has a distinct lunule or dorsal depression, divided by a slight central ridge, and
it is more tumid. The anal region also has apparently a more prominent centre and
deeper external depression.

19. Nucuua sericea, S. Wood. Tab. XIX, fig. 3.

Spec. Char. N. testd tenui, transversd, subtrigonuld, levigatd, glabra, calvatd aut
obsolete radiata ; pedi-reyione producta, angulatd ; siphoni-regione obliqué truncata, sub-
attenuata ; lunuld inconspicud ; margine dorsali convexiusculd ; margine ventrali arcuata ;
umbonibus acutis, terminalibus ; marginibus crenulatis.

Shell thin, transverse, subtrigonular, smooth, glossy, naked, or with obsolete radiating
strie ; pedal region produced and angulated; siphonal side obliquely truncated, and
somewhat pointed ; lunule inconspicuous; dorsal margin slightly convex, ventral margin
more curved; beaks terminal; inner margins crenulated.

Length, } an inch.

Localities. White Cliff, Hunting Bridge (4dwards).

This species somewhat resembles prelongata and protracta, but it protrudes more on
the siphonal side, and the ventral margin is more rounded. It differs also in the anal

120 EOCENE MOLLUSCA.

region, and it is comparatively shorter. The shell is thin, and there is no perceptible or
distinct lunule on the pedal region; neither is there any distinct corselet. The specimens,
which are few in number, adhere firmly to the matrix, and I am unable to see the
interior.

20. NucuLa suprransveRSA, JVyst.? Tab. XIX, fig. 13.

NvucuLa sUBTRANSVERSA. Nyst.? Coq. Foss. Belg., p. 227, pl. xviii, fig. 7, a, 6, 1844.
— OVATA. Id.? Rech. Coq. Foss. de Hoesselt et Kl. Sp., p. 13, No. 3],
1836.
— — Potiers et Mich.? Catal. de Moll. de Douai, t. ii, p. 120, No. 3, 1844.

Spee. Char. N. testd transversd, oblongo-ovatd, turgidd, valdé inequilaterali, obsolete
radiata; pedi-regione prelongd, paulo attenuata; margine dorsali subrectd ; margine
ventrali convewiusculd ; lunuld inconspicud ; ano ovalo, in medio prominenti ; marginibus
crenulatis. d

Shell transverse or elongate, ovately oblong, or obtusely wedge-shaped ; very inequi-
lateral ; obsoletely radiated; pedilateral margin slightly pointed ; dorsal margin nearly
straight ; ventral margin gently curved; corselet or anal region ovate, elevated in the
middle; margins crenulated.

Length, ths of an inch; height, jths of an inch.

Locality. White Cliff Bay (/%sher).

The specimen figured enriches the cabinet of Mr. Fisher, who tells me it is not rare,
but very difficult to obtain in any degree of perfection.

I have considered it as identical with the Belgian species, depending entirely for so doing
upon figure and description, although the proportions given by M. Nyst do not quite accord
with those of our own shell. ‘This is extremely transverse or elongate—more so than any other
species from the English Hocene deposits ; and the umbo, which is depressed and much
eroded, is at the extremity of the shell, the siphoni-lateral margin forming aimost a right
angle with the dorsal edge. ‘The outer surface shows distinct but irregular lines of
increase, and the nearly obsolete rays upon the specimen are most visible towards the
pedilateral margin, as they are described to exist on the Belgian shell.

M. Nyst points out a distinction which exists between his shell and the one which he
considers to be the same from the Paris Basin in the number of the hinge-teeth. Unfor-
tunately I am unable to ascertain the dental characters of our shell.

BIVALVIA. 121

21. Nucunra THanatrana, Ldwards, MS. Tab. XIX, fig. 6.

Spec. Char. N, testd ovato-trigond, convewiusculd, tenui, valde inequilaterali, radiatin
striata ; striis tenuibus, sub-decussatis ; lunuld nulld aut indistinctd ; ano plano, levigato ;
cardine crassiusculo, umbonibus minimis ; marginibus dorsali et ventrali converiuscws ;
margine ventral erenulata.

Shell ovately triangular, rather convex or tumid, thin, very inequilateral, and covered
with radiating striz ; striee fine and irregularly decussated ; no distinct lunule ; siphonal
or anal region flattish and smooth ; hinge rather thick, umbones small ; dorsal and ventral
margins slightly and nearly equally convex ; margins crenulated.

Length, § an inch.

Locality. Pegwell Bay (Hdwards).

The figure above referred to was taken from an unique specimen in Mr. Edwards's
cabinet, of which the umbo was not quite perfect ; it represents the shell as rather more
elongated than it ought to be.

22. Nucuna rumxscens, Hdwards, MS. Tab. XVIII, fig. 1 a—e.

Spec. Char. NN. testé ovato-trigonuld, tumescenti, crassiuscula, levigatd, obsolete
radiataé ; pedi-regione sub-cuneatd; siphoni-regione brevissimd, truncata ; umbonibus ter-
minalibus, depressts ; lunuld indistinctd ; marginibus crenulatis ; dentibus numerosis, ad
apicem decrescentibus.

Shell ovately triangular and wedge-shaped, tumid, rather thick, and smooth; pedal
region obtusely wedge-shaped ; siphonal region very short; exterior obsoletely rayed ;
beaks terminal, depressed ; lunule indistinct ; anal region marked with an obtuse elevation
or ridge; margins crenulated ; teeth numerous, decreasing towards the umbo.

Length, } an inch; height, &ths of an inch.

Localities. Mead End, Barton (Hdwards).

This is not rare. ‘The principal distinction of the species is its great tumidity, thereby
giving more than ordinary depth to the interior of the umbonal region.

23. Nucuta WeraerELLi, J. Sowerby. Tab. XIX, fig. 9 a, 6.

NucuLa WETHERELLIT. J. Sow. Geol. Trans., 2nd ser., vol. v, pl. viii, fig. 12, 1834.
“ = Prestwich. Geol. Journ., 1847, p. 405.
—_ —- Morris. Catal. Brit. Foss., p. 218, 1854.

122 EOCENE MOLLUSCA.

Spec. Char. NV. testé ovatd, viv elongata, gibbosd, levigatd, subinequilaterali ; pedi-
regione rotundata ; siphoni-regione oblique truncaté vel obtusé rostrata ; umbonibus depressis ;
marginibus crenulatis.

“ Shell suborbicular, transverse, gibbose, smooth; extremities pointed ; beaks nearly
central, margin obtuse, edge toothed.” — J. Sowerby.

Length, ¥ an inch.

Locality. Wampstead Heath (Wetherell) ; Highgate, Sheppy ? (Zdwards).

“The radiating structure of this Nucula, common to the species of the genus, is very
conspicuous, but the inner surface is not striated, as in V. Bowerbankii.”—J. Sowerby.

The specimens of this species that I have seen are not numerous, and, unfortunately,
they are not in perfect condition; the umbones are excessively eroded, thereby reducing
their natural proportions, giving a slightly rounded outline to the shell.

Since the type for the preceding descriptions has been set up, several specimens
belonging to this genus have come under my inspection, which I cannot assign to any of
the foregoing species ; and although they do not present characters sufficiently determinable
for specific isolation and description, they are, I conceive, fully deserving of representation
and notice, and I propose here to give to them provisional names only until they can
hereafter, by the possession of more specimens, be satisfactorily characterised.

Tab. XX, fig. 10, represents the interior cast of a shell from Clewer Green, near
Basingstoke, kindly lent to me by Mr. Prestwich, and to which I will give the name of
LV. venusta ; it appears to have possessed a smooth margin to the edge of the valves, and
it has a very slight basal projection on the siphonal side; there is a prominence in the
anal region, and in its contour it is intermediate between JV. disulcata and WN. prelonga,
but to neither of those smooth-margined species can it, I think, be referred. The age of
the deposit i which it is found being greater than that of the two other species strengthens
the supposition that this is distinct.

Tab. XX, fig. 7, is the representation of a specimen, also from Mr. Prestwich’s cabinet,
to which the locality Cuffells is attached; this appears to be different from any of the
foregoing, but it is imbedded in the matrix, and I am unable to describe its true characters.
I give it the name of JV. consobrina ; in outline it somewhat resembles JV. consors, from
Highgate, but is, I think, too long and too much truncated for that species ; it has a very
slight elevation in the anal region, but there is no perceptible lunule, although there is a
slight depression on the dorsal surface extending from the umbo to the verge of the pedal
extremity ; the shell is thick, nacreous within, and the .denticles are large, twenty-four on
the pedal side, and seven or eight on the other.

Tab. XX, fig. 6, represents a specimen very recently obtained from the Woolwich
series at Bickley, by Chas. A. Meyer, Esq.; this shell has been kindly submitted to my
examination. It is probably distinct, and I will call it for the present M. gracilenta ; its
nearest relative appears to be WV. fragilis, but on a comparison with specimens of that

BIVALVIA. 123

species in the British Museum, it presents the following differences :—J. fragilis has
the basal margin on the anal side more pointed, with the centre of the anal region more
elevated and distinct, and the pedilateral margin is not quite so much rounded: there
appears also to be a difference in the number of denticles, but a larger number of specimens
will be required to determine its correct position.

Tab. XX, fig. 9, is a shell recently obtained by Mr. Gibbs from the Basement-bed of
the London Clay at Herne Bay, and the officers of the Museum in Jermyn Street, to
which it belongs, have kindly permitted me to have it figured. I am unable to refer it to
any known species, and propose to give to it the name of JV. striatella. It appears to be
specially distinguished by an unusually prominent anal region ; it is finely rayed, and the
margins are denticulated,

Tab. XX, fig. 8 a, represents a specimen also from the Thanet Sands at Herne
Bay. This I at first thought to be probably the perfect condition of VV. cardiovdes,
which the young or unmutilated portion of that shell somewhat resembles; but upon
close comparison the two specimens do not satisfactorily accord. Mr, Edwards has
given to this specimen the MS. name of sextans, the outline of it forming somewhat
irregularly the sixth part of the circle. Fig. 8 4, of the same plate is the likeness of a shell
in Jermyn Street, from Herne Bay, which may probably belong to the same species, coming,
as it does, from the same bed ; but I have had it represented in consequence of a difference
in outline, it being less triangular than fig. 8 a, the dorsal margin on the pedal side being
more convex, and the pedilateral margin less pointed. ‘lhe anal region (which, I think, in
general affords a good auxiliary character) is, unfortunately, in this specimen broken.

The recent discovery of these last-noticed specimens has caused considerable delay in
the preparation of my work, but they appear of so much interest and of so much importance
towards a history of the contents of our Hocene deposits, that I thought it would not be
pardonable to pass them over, and now, at the eleventh hour, another shell has come into
the possession of Mr. Edwards, which appears to me to be also worthy of especial notice,
and I have had it figured.

Tab. XIX, fig. 21.—This last specimen is a very elegant shell; it approaches in form
very closely to WV. /evigata of the Crag, and I have given to it the name WV. prelevigata,
in consequence of its very near relationship. It is excessively thin, quite smooth externally,
and it has amargin free from crenulations; it differs from WV. proava in being thinner, and in
having the anal region shorter than in that species ; and it differs from JV. /evigata in having
a depression or shallow sulcus on the dorsal region beneath the dental edge; the curva-
ture of the ventral margin, although nearly as great as in the Crag shell, is not quite so.
regular, and the pedilateral margin being a little broader in our present specimen, will
distinguish it. The interior I have not been able to examine. ‘The shell is too thin and
too firmly imbedded in the matrix to permit of removal.

17

124 KOCENE MOLLUSCA.

LEDA. Schumacher, 1817.

Generic Character. Shell equivalve, inequilateral, elongate, lanceolate, or elliptical,
sometimes fig-shaped, rounded at the pedilateral margin; siphonal region more or less
pointed or rostrated ; umbones small, approximate ; hinge with numerous sharp, generally
angular, and interlocking teeth, separated by a spoon-shaped or triangular fossette ; con-
nexus cartilaginous ; palleal line sinuated, with a linear impression, more or less distinguished,
extending from the middle of the umbonal region to the base of the oral adductor muscle-
mark. In the recent state the shell is covered by a thick epidermis.

Animal with the mantle open in front, margins simple, sometimes fimbriated ; foot large,
discoidal, with serrated edges; siphons slender, unequal, partially united.

This genus is distinguished from Vucula by the prolongation or extension of the siphonal
region making some of the species equilateral, or even reversing the comparative dimensions,
giving the smaller and shorter portion to the pedal side. Méller has subdivided this
genus, and proposed the name of Yo/dia for those shells which gape on each side.
These two names are still adopted by some authors, who maintain the distinction to be
sufficient for generic division. Mérsch has made another division for those which are
closed at both extremities, and for which he proposes the generic name of Portlandia,
while Leda proper is said to gape only onone side. The distinctions here spoken of are,
I fear, very unstable, and will probably, by the greater number of conchologists, be considered
only of specific value. So/inel/a has a similarly shaped shell, with the dental area furnished
with a row of small, sharp, angular teeth on each side of the umbo similar to those of the
present genus ; but the connector there is wholly ligamental, situate externally upon a pro-
jection or fulcrum, and this character fairly entitles the shell in question to generic
distinction.

The shells of this genus (Leda) are often quite smooth; but some have concentric
ridges or thickened lines of growth, and a few are ornamented with ridges in an oblique
direction, the inner margins of the shells are at all times free from crenulations.

Species of this genus in the recent state have been found in all parts of the world and
in all climates, and at all depths: upwards of seventy have been described ; and in the
‘Proc. of the Nat. Hist. Soc. of Philadelphia,’ 1860, p. 49, Mr. Binney called attention
to a species of Zeda which Dr. Gould says is common to the seas of Japan and to the coast
of Massachusetts.

In the fossil state they are also numerous, and have been found low in the Secondary
formations.

bo
ot

BIVALVIA. ]

1. Lepa amyepatorpss, J. Sowerby. Tab. XVII, fig. 6, a—e.

Nucuva amMyGpaLoiweEs. J. Sow. Min. Conceh., t. 554, fig. 4, 1821.
— — Wetherell, Tr. Geol. Soc., 1834, p. 134.
-- = Morris. Catal. Brit. Foss., p- 217, 1854.

Spec. Char. L. testdé elongato-ovatd, crassd, tumidd, sub-aequilaterali ; concen-
tricé striatd, striis obtusis rotundis ; pedi-regione ovato-rotundatd ; siphoni-regione obtuse
rostrata ; ared dentali crassiusculd ; fossuld conneatis minutd, profunda.

Shell elongately ovate, thick, tumid, glossy, nearly equilateral, and concentrically
striated ; striae rounded; pedilateral margin ovately rounded; siphonal region obtusely
pointed ; dental area rather thick ; cartilaginous depression small.

Length, \ inch ; height } an inch.

Localities. Tghgate, Potter’s Bar, Wandsworth, Sheppey, Hampstead, Southend,
Whetstone Park, Finchley, Hornsey (Ldwards and Wetherell), Cuffells (Prestwich).

This is an elegant shell, and abundant in some localities, but seldom found with the
valves separated. Casts of this shell (at least what appear to be so) are found at Sheppey.
‘The nearest approach to this species is V. Deshayesiana, Nyst (‘ Coq. Foss. Belg.,’ p. 221,
pl. xv, fig. 8); but that shell differs in being larger, thicker, with a more inflated and
more prominent umbo ; the striz in the British shell extend to the extreme margins, and
cover the entire surface, as they do also in WV. Deshayesiana. There is a distinctly marked
corselet as well as lunule on each side of the umbo, with an elevated ridge ; this is not so
distinctly marked in the Belgian shell, and the siphonal region of this latter species is
rather the more pointed of the two. There are about fifteen or sixteen denticles on each
side of the hinge-area of our shell, and the sinus in the mantle-mark is very shallow.

2. Lepa costunata, Deshayes. Tab. XVIII, fig. 3, a, 4.

Lepa costuLata. Desh. An. sans Vert. du Bass. de Par:, t. i, p. 829, pl. 65, figs. 8—10,
1858.

Spec. Char. L. “ testd ovato-transversd, subtrigond, soliduld, depressiusculd, equilateral,
anticé obtusd, posticé vie rostratd, transversim regulariter sulcatdé ; umbonibus minimis,
conniventibus ; lunuld levigatd, viv distinctd ; ano clongato, lanceolato, convexiusculo, angulo
obluso separato ; margine cardinali angusto ; dentibus serialibus minulissimis, approximatis ;
Jossuld ligamenti minutissimd.”’—Desh.

Shell elongate, ovately subtrigonular, strong, somewhat depressed, equilateral ; pedilatera]
margin ovately rounded; siphonal region scarcely rostrated, covered concentrically with broad
ridges and furrows ; beaks small; lunule indistinct ; corselet elongate, slightly convex, ex-

126 EOCENE MOLLUSCA.

tending the length of the siphonal region; hinge-area narrow, with a small pit for the
connector.

Length, + inch; height, 3ths of an inch.

Locality. Bracklesham (Hdwards). ,

A single specimen is in the cabinet of Mr. Edwards; it is the only one I
have seen, and, judging from the figure and copious description given by M. Deshayes,
I feel no hesitation in referring it to this elegant species. I agree fully in opinion
with M. Deshayes that it is quite distinct from Leda striata of the Paris Basin,
and it is still further removed from what has been called Leda striata from our own
deposits.

The siphonilateral margin of our shell is more rounded and less pointed than that of
L. striata, and it corresponds in that character both with Z. odlata and L. amygdaloides ;
but it differs from the former in being entirely covered with ridges, and in being also
more equilateral ; and from the young of the latter in having the ridges much larger and
more distant, and in being comparatively shorter. The dental margin is very narrow,
and is furnished with about a dozen denticles on each side of the cartilaginous pit, which
is also comparatively small; the shell is thin, and the muscle-mark on the siphonal side is
large; the external ridges are visible in the interior: Shell nacreous.

3. Lepa Gatzortiana, Wyst. Tab. XVII, fig. 2, a, 6.

Nucuta mucronata. Galeotti. Mém. Const. Géol. Prov. de Brabant, p. 155, No. 123,
1837.
— _— Nyst. Coq. Foss. de Belg., p. 223, pl. 18, fig. 3, 1844.
— sERRATA. Jd. Sow. in Dixon’s Geol. of Sussex, pp. 93, 170, pl. 2, fig. 9, 1850.
Lepa GaLeorrrana. D’Ord. Prod. de Paléont., t. ii, p. 378, No. 808, 1850.
— — Desh. An. sans Vert. du Bass. de Par., t. i, p. 830, pl. 66, figs. 1—3,
1858.
— seERRATA. Morris. Catal. Brit. Foss., p. 206, 1854.

Spec. Char. L. testd minima, depressd, ovato-lanceolatd, subequilaterali, pedi-regione
ovato-rotundatd, siphoni-regione rostrato-acuminatd ; concentricé striata vel costaté ; striis
paucis, magnis, elevatis ; lunuld lanceolatd paulo excavatd ; ano magno, bipartito ; umbo-
nibus depressis ; marginibus integris.

Shell small, depressed, elongately ovate, nearly equilateral; pedal region ovately
rounded ; siphonal region angularly pointed ; covered with a small number of elevated ridges
or lines of growth; lunule elongated and somewhat shallow; beaks depressed, margins
smooth.

Length, : meh ; height, th inch.

Locality, Bracklesham (Ldwards).

BIVALVIA. 127

France: Damery, Montmirel, Courtagnon (Desh.).
Belgium : Les sables de Laecken, de Jette, de Forét, et de Louvain (Wyst).
This elegant little shell appears to be rare. The ridges on the exterior are elevated,
distinct, and large, with deep furrows between them ; the furrows are nearly as broad as
the ridges. On the siphonal region there is a distinct and elevated keel, sloping from the
umbo to the extremity of the siphoni-lateral margin.

4. Lupa minima, J. Sowerby. Tab. XVII, fig. 7, a—e.

NucvLa MINIMA. J. Sow. Min. Conch., t. 192, fig. 8, 1818.

Spec. Char. L. testa minima, ovato-lanceolatd, elongata, tumidd, subequilateral,
concentricé striata striis numerosis prominentibus ; pedi-regione rotundatd ; siphoni-regione
rostrata, sub-acuminatd ; umbonibus minimis, approximatis; ano magno, lanceolato, angulo
mediano bipartito, angulo obtusiore conscripto ; cardine crassiusculo, multidentato ; fossuld
minima, profunda.

Shell small, elongately ovate, tumid, nearly equilateral; pedal region rounded, siphoni-
lateral pointed; beaks small, approximate, covered with concentric striz or ridges ;
corselet distinct, elevated in the centre; dental margin thick, with numerous teeth ; car-
tilaginous support small and deep.

Length, + of an inch; eight, +th of an inch,

Locality, Barton, Bracklesham, Bramshaw, Brook, Highcliff (Hdwards).

‘There are three or four species of this genus about the same magnitude, possessing
many similar characters, which have been found in the British Eocene deposits, and it is
somewhat difficult to say which was the one intended by Mr. Sowerby for WV. minima.
The present one is abundant, and probably was the one his figure is designed to
represent. He says, “'Transversely ovate, convex, transversely striated.” The strice in
this species cover the entire surface; they are fine and rounded, extending from the
pedilateral margin to the angular ridge on the slope of the siphonal region, beyond which
is a large corselet; this is of a lanceolate form, divided by a central ridge, the upper
portion of which is finely striated. There is a row of angular teeth (at least a dozen) on
each side of the cartilage-pit.

‘There are two varieties of this shell, one of which strongly resembles the figure of
L. gracilis, Desh. (‘ An. sans Vert. du Bas, de Par.,’ p. 831, pl. 64, figs. 24—26); and
several differences are presented, as might be supposed, among our numerous
specimens ; some have the pedal region almost smooth, as if from abrasion on that part,
which is generally buried by the animal in the living state.

128 EOCENE MOLLUSCA.

5. Lepa opuata, S. Wood. ‘Tab. XIX, fig. 10.

Spec. Char. LL. testé minima, elongato-ovatd, oblataé, levissimd, glabra, subequila-
ferali ; pedi-regione tumidd ; siphone-regione compressiusculd, margine obtuse rostrata ;
umbonibus prominulrs.

Shell small, elongately ovate, externally smooth and glossy, slightly inequilateral ;
pedal region tumid and rounded; siphonal region compressed ; obtusely rostrated ; beaks
slightly prominent.

Length, 3rd of an inch.

Localities. Chalk Farm (Wetherell), Potter’s Bar (HLdwards).

There are a few specimens in Mr. Wetherell’s cabinet, and also in Mr. Edwards’s,
which very much resemble, in outline and general characters, Z. partim-striata from
Highgate and Clarendon; but they differ im having the exterior perfectly smooth and
glossy, and appear to be quite free from the ridges which ornament the centre or ventral
portion of the shell of that species. This species presents some resemblance to the variety
L. prisca, from Highgate; but the shell is larger, and the siphoni-lateral margin is not so
pointed. The specimens are too closely imbedded in the clay to permit of removal,
and the interior is consequently invisible.

6. Lepa prisca Deshayes. ‘Tab. XVII, fig. 4, a—d.
Lepa Prisca. Desh. An. sans Vert. du Bass. de Par., t. i, p. 830, pl. 65, figs. 15—17.

Spec. Char. L. “ testé minima, obovata, tumidd, levigatd, politd, strits incrementi vix
conspicuis ; anticé rotundatd ; posticé angulatd, acutd, cuneatd ; umbonibus submedianis,
depressis ; lunuld ellipticd ; dentibus 8—9 utroque angulatis ; marginibus integris.”

Shell small, obovate, tumid, or inflated ; smooth, glossy, with scarcely visible lines of
growth ; one side rounded and the other angulated and sharp or wedge-shaped ; umbones
subcentral, depressed ; lunule elliptical; denticles about 8—9 on each side; margins
smooth.

Length, ths of an inch; height, jth of an inch. 2

Localities. Var. a, Highgate (Wetherell) ; var. B, Barton (Ldwards aud S. Wood).

‘his pretty little shell is by no means abundant. It strongly resembles Z. pygmaea,
the existing British and Mediterranean species.

There are two British Eocene shells that I think may be assigned to the French
species; they differ a little in the number of denticles; the one trom Ilighgate cor-
responds closely with the description given by M. Deshayes ; the other, from Barton, does
not appear to have quite so many teeth in the hinge-line. hey both differ from

BIVALVIA. 129

L. pygmaea in being rather more pointed or angulated at the siphoni-lateral margin, with
a less elevated umbo, and there is a rather large cartilaginous area and a narrower hinge,
the shell also is more tumid.

The Highgate variety of Z. prisca is most probably 1. minima of ‘Min. Conch.,’
t. 192, fig. 9, which Mr. Sowerby suspected might be the cast of another species.

7. Leva partim-staiata, 8S. Wood. Tab. XVII, fig. 1, a—c.
NucuLa striata, var. J. Sowerby. Trans. Geol. Soc., 2nd ser., vol. v, pl. viii, fig. 12, 1834.

Spec. Char. L. testd elongato-ovatd, oblatd, tumidd, tenui, subequilaterali; pedi-
regione convexd, siphoni-regione longiore et obtuse rostratd ; in medio longitudinalter
costaté vel sulcatd ; utrinque levigatd ; umbonibus prominulis.

Shell elongately ovate, oblate, tumid, thin, inequilateral; pedal region convex ; siphonal
region the longer, laterally compressed, and obtusely rostrated; central region longitu-
dinally ridged, with both extremities smooth; beaks slightly prominent.

Length, sed of an inch.

Localities. Clarendon, Highgate, Potter’s Bar, Haverstock Hill, Alum Bay (2dwards),
Hampstead Heath (Wetherelt).

Although this species appears to have had an extensive geographical range, it is
nowhere found in abundance.

The species to which it approaches nearest is WV. amygdaloides, Sow., from which,
however, it differs in being only partially covered with ridges, and it is also more inflated
and more obtuse. ‘The ventral region is covered with ridges, but the pedal, as also the
siphonal sides, are quite smooth. The shell is tumid only in the pedal and central
regions ; and compressed on the siphonal side.

8. Lepa propinava, 8S. Wood. Tab. XX, fig. 2.

Spec. Char. L. testé minutd, ovato-subtrigonuld, conveaxiusculd, sub-inequilaterali, tenui,
levigatd ; pedi-regione elongato-ovatdé vel semi-ellipticd ; siphoni-regione subrostratad et
angulataé ; umbonibus depressis, utrinqué sub-aqualiter declivis, lunulié anoque vie perspreuis.

Shell small, ovately triangular, slightly convex, nearly equilateral, thin, and smooth ;
pedal side elongately ovate or semi-elliptical ; siphonal side obtusely rostrated or dorsally
angulated ; beaks depressed, with nearly an equal slope on each side ; lunule and corselet
scarcely perceptible.

Length, 3ths of an inch; eight, half the length.

Locality. Colwell Bay (Zdwards). |

130 EOCENE MOLLUSCA.

A single specimen from the above locality is in Mr. Edwards’s cabinet, and this I am
unable satisfactorily to assign to any other species. I therefore give it the above name
provisionally. The species this shell most nearly resembles is Z. od/ata, from Highgate,
but the present shell is thinner and flatter; it is also comparatively longer, and the
siphoni-lateral margin is more pointed. Our shell appears to be quite smooth upon the
exterior, and glossy; the dorsal margin on the pedal side is slightly convex; on the
siphonal side it is nearly straight. The specimen is firmly imbedded in the matrix.

9. Lepa susstriata, Morris. Tab. XVII, fig. 5.
Lepa susstriaTa. Morris. Geol. Journ., vol. viii, p. 266, pl. 16, fig. 7, 1852.

Spee. Char. LL. testé minima, ovato-elongatd, subtrigond, tumidiusculd, sub-inequi-
lateral, concentricé striaté aut obtusé costatd ; pedi-regione ovato-rotundatd ; siphoni-
regione longiore, subrostratdé et sublevigatd ; umbonibus prominulis ; lunuld via distineté ;
ano elongato, lanceolato.

Shell small, ovately elongate, obtusely trigonular, rather tumid, slightly equilateral ;
concentrically striated or obtusely ridged; pedilateral margin ovately rounded; siphoni-
lateral obtusely pointed; beaks prominent; lunule ill defined.

Length, *ths of an inch; height, 4 of an inch nearly.

Locality. Richborough (Prestwich), Pegwell Bay (dwards).

“This shell, collected by Mr. Prestwich from the Thanet sands at Richborough,
Castle and Pegwell Bay, is difficult to distinguish from MWwcula striata, Lam., which it
resembles in general form, but is rather longer in a transverse direction, and the stric
differ a little, and are interrupted towards the posterior margin in some of the specimens
examined.” —Morris.

In addition to the above remarks I may observe, that the French shell has different
proportions: the siphonal region is rather less than the pedal, whereas in the British shell
it is the reverse. ‘This species appears still more to differ from Leda minima, which has a
distinct and well-marked anal or corselet region, with a defined and prominent ridge,
and the siphoni-lateral margin is in that shell more pointed than in either our present
species or the French shell Z. striata.

UNIO. Phillipson, 1788.

Generic Character. Shell equivalve, inequilateral, generally thick and externally
smooth, occasionally corrugated or ornamented with nodules or spines; aged specimens
sometimes become ponderous. Covered by an epidermis in the living state; eroded at
the umbones; hinge with two short cardinal teeth in the left valve, and one, sometimes
two, in the right, and one elongated lateral tooth beneath the dorsal margin. Impressions

BIVALVIA. 131

by the adductors large and deep; pedal muscle-marks distinct—one double, situate near
and below the oral, the other single, and above the anal adductor; mantle-mark without
a sinus; shell nacreous; connexus ligamental.

Animal with the margins of the mantle disunited, except between the siphonal
openings ; tubes short—one fringed, the other plain; foot compressed.

Variations in the fresh-water mussels are numerous and excessive, and many
genera, with very ill-defined lines of distinction, have been proposed for their reception.
Unios are of a peculiar construction, being formed almost entirely of nacre; and some of
the recent species not only display a beautiful pearly lustre, but are of a purple, pink, or
salmon colour in the interior. Colour, Mr. Lea says, is not always to be depended upon
for a specific distinction.

This genus is found in the Wealden formation, and is said to have been in existence
during the Carboniferous period.

Mr. Lea, who is our best authority on this subject, says of this genus that there are
already described, as inhabiting the rivers, lakes, and pools of the United States and Terri-
tories, 465 species, to which several more in his own cabinet will have to be added; and
he considers that there are upwards of 600 species belonging to the family Unionidze that
are peculiar to North America. This large number is, perhaps, the more extraordinary
when compared with the number of existing species on our own continent. Mr. Lea
further says (‘ Proc. Acad. Nat. Sc. Philad.,’ p. 3, 1860), that he had taken great pains to
procure specimens from all parts of Europe, “and he was satisfied that there were ninety-
-eight synonyms made by European authors for the single species Axodonta cygnea,
Drap. (Mytilus cygneus, Linn.), and that the synonomy is nearly as profusely erroneous in
Unio pictorum, Unio tumidus, Unio Batavus, and Unio littoralis”’ The number of recent
species he has allotted to Europe is seven Uniones, one Margaritacea, one Monocondylea,
and one Anodonta. This great discrepancy between the numbers on the two continents gives
to North America a preponderance of sixty-fold over those of Europe. ‘The extent of fresh
water in the rivers and lakes of America may in some degree be assigned as a cause for
the very great development of species in that continent over those in Europe; but that
alone appears insufficient for explanation, as the proportions of fresh water between the
two continents will not bear a comparison with this disproportion of species, more espe-
cially when we consider that it is principally on the shores of these extensive lakes, or at
least in not very deep water, that we are likely to find living many of the species, and
can hardly take imto our computations the fresh-water area of North America. This
would materially reduce the apparent excess in the area of feeding-ground for these animals
in America over that in Europe, and it does appear to me that some other cause than
mere difference in the superficial extent of the medium in which they live, is required to
account for this great difference in the relative number of the species found in the two
Continents. We have, according to Mr Lea, ninety-eight synonyms in a single European
species, thereby implying very great variation; but to what extent we are permitted to _

18

132 EOCENE MOLLUSCA.

carry our opinions respecting what amounts to simple variation and what constitutes
specific distinction will probably long be matter for dispute. The differences in America,
considered sufficient for specific isolation according to this author, appear to be more
clearly defined than they are with us. We have nothing in other sections of the Mollusca,
either marine or terrestrial, that will bear a comparison with such an enormous difference
in the number of species as is alleged to be exhibited in this family, and if correct (and
I am not able to say that it is otherwise) it is an anomaly in the history of the Mollusca.

The remains of fresh-water deposits of any past period give comparatively a very limited
number of species in this family, bearing in that respect a resemblance to the dissemination
of these animals on the continent of Europe. I have here figured seven species from the
Eocene deposits of England, but these are not at all well defined; and there are nine or
ten in those of France. The Upper Tertiary species are, I believe, still existing. We might,
perhaps, expect that the limited number of living species should have descended from a
limited number of their predecessors; but the fresh-water Tertiary deposits of America
appear also to have been but sparingly supplied by these animals, while the specific deve-
lopment in this family at the present day in America is out of all proportion when the
present is compared with the past, as is here attempted to be done with the Tertiaries of
Europe and their descendants. |

M. Deshayes considers one of the French Eocene shells U. Michaudi, to be very closely
related, probably the same, as a living species in North America, U. cicatricosus ; but I
have not been able to identify any one of our own. ‘This may arise from a want of
acquaintance with the numerous existing species of the American waters, where almost
every conceivable form of the genus is represented. On a comparison with the figures
and descriptions of the existing shells, given by Mr. Lea, there may be pointed out two or
three which very closely resemble those of British Eocene species; and when each comes
to be better known, and the specimens themselves compared, it is possible that one or
more may be found to have retired from England in the direction of America after the
Hocene period, through land, or rather rivers, that probably existed at that time on the
western side of the Eocene sea of Europe, such as has been the case with peculiar genera
of fresh-water fish and reptiles now confined to the American continent. Our own fossils
in this genus, from the older Tertiaries, are generally far from being in a perfect state of
preservation, so that no fair comparison can be made or relied upon. The specific separa-
tions here proposed must for the present be considered merely as provisional; for with
the fate of an existing European species before our eyes, with its ninety-eight synonyms,
it would be hazardous in the extreme to pronounce decisively upon the few and in most
instances imperfect specimens hitherto obtained from our Eocene deposits.

BIVALVIA. 133

1. Unto Austeni, Forbes, MS., and Morris. Tab. XX, fig. 12.

Usio Austentt. Morris. Mem. Geol. Surv:, p. 147, pl. 2, fig. 7, 1856.

Spec. Char. “ Testé oblonga, ovali, modioliformi, posticé obtusé rotundatd ; margine
dorsali leviter arcuato ; margine ventrali subrecto ; umbonibus feré terminalibus.

“An oblong, depressed, modioliform shell, somewhat expanded, and rounded posteri-
orly; the umbones are depressed and nearly terminal; the surface is but obscurely
striated.” —Morris.

Locality. Hempstead.

The only specimen that I have seen is the one which enriches the Museum in Jermyn
Street, and on which the species has been established. ‘The principal character of dis-
tinction appears to me to be its inequilaterality, which is in excess.

2. Unto Epwarpsit, S. Wood. Tab. XX, fig. 16, a, 4.

Spec. Char. U. testa elongato-ovatd aut elongato-cuneatd, crassa, irregulariter et con-
centricé sulcatd vel corrugatd, inequilaterali, convexiusculd ; pedi-regione obtuse rotundata ;
siphoni-regione valde longiore et obtuse acuminatd ; margine ventrali subcurvato.

Shell elongately ovate or wedge-shaped, thick, and irregularly ridged by lines of growth,
slightly convex or tumid ; pedilateral margin obtusely rounded ; siphonal region much the
longer and roundedly pointed; ventral margin slightly curved.

Length, 2 mches ; heaght, 14 inch.

Locality. Peckham (Hdwards).

Specimens of this species are few and imperfect, but the form is peculiar, differing
from that of any other Eocene species; it much resembles U. pictorum, but it is not
sufficiently pointed on the siphonal side, and it is more inequilateral. One of our figures
represents a specimen that has lost nearly the whole of the shell, but it gives a very good
representation of the outward form; and the other figure shows the exterior to have been
more than usually rugged or corrugated, from which circumstance the specimens have had
attached to them in Mr. Edwards’s cabinet the MS. name of corrugata, which I should
have adopted, had it not been employed for a recent species in America. I therefore
propose for our shell the name of the Author of the ‘Monograph on the Eocene Mollusca.’

3. Unto Gisssit, Forbes, MS., and Morris. Tab. XX, fig. 14.
Unto Gippsi1. Morris. Mem. Geol. Survey, p. 147, pl. 2, fig. 6, 1836.

Spec. Char. “ Testa elongato-ovatd, transversd, utrdque extremitate obtusa, sed posticé
obscuré angulata ; margine ventrali subrecto.

134 EOCENE MOLLUSCA.

“ An ovate, elongate, or somewhat quadrate shell, with the anterior extremity rather more
rounded than the posterior, which is slightly angulated and truncated.

“The specimen figured has undergone some compression, which has partially modified
the original form. It was considered, and therefore figured, as a distinct species by Pro-
fessor E. Forbes; it is, however, closely allied to and difficult to distinguish from some
varieties of U. Solandri.” —Morris.

Locality. Hempstead Ciiff.

I am much inclined to think, with Professor Morris, that it is only a variety (and that
not a very distinct one) of U. Solandri.

4. Unto Sonanprtl, J. Sowerby. Tab. XX, fig. 11, a, 3.

Unto Souanpri. J. Sow. Min. Conch., t. 517.
—_ — S. Wood. Catal. in Lond. Geol. Journ., p. 118. 1847.
— — Wright. Ann. and Mag. Nat. Hist., June, 1851, p. 6.
— — Morris. Catal. Brit. Foss., p. 230, 1854.

Spec. Char. U. testdé transversd, oblonga vel subrhomboidali, compressa valdé in-
aequilaterali ; pedi-regione rotundaté, siphoni-regione truncatd ; valvis tenuibus ; um-
bonibus vie prominentibus ; dente cardinali parvo, laterali elongato ; striis crescentibus
exilissimis.

Shell tranversely ovate, oblong, and slightly compressed, very inequilateral ; pedilateral
margin rounded, the opposite one somewhat angularly truncated ; valves thin; umbones
depressed ; cardinal hinge-tooth small, with an elongated lateral tooth ; connexus short ;
lines of increase very fine.

Length, 13 inch, breadth, ths inch.

Localities. Hordwell, Colwell Bay.

Although so common as this shell is at Hordwell, it does not appear to have been
known to Solander, at least he does not figure it.

The shell called Mya pictorum, Foss. Hant. fig. 95, referred to in ‘ Min. Conch.,’ vol. vi,
p. 29, with a?, is probably Cytherea levigata. The shells at Hordwell are in great profusion,
but they are exceedingly fragile, and generally exfoliated, so that it is very difficult to obtain a
perfect specimen. ‘The proportions in magnitude of this shell are generally about two in
length to one in height, and rather more than half a one in thickness or tumidity. The dorsal
and ventral margins are nearly parallel, or with a very slight curve inwards in the ventral
margin, and the siphonal is three times the length of the pedal region. In the right. valve
there is one rather prominent tooth a little on the pedal side of the umbo, and this is
obsolete in the left valve; the elongated lateral tooth is the reverse of this, being prominent
in the left valve and obsolete in the right. ‘The oral muscle-mark is of a moderate

BIVALVIA. 135

size, deeply impressed, and there is a distinct pedal one within and a little below it; the
anal one large and remote; the umbones are rugose, and generally eroded. The epidermis
is visible on well-preserved specimens, which have also the connector entire, extending from
the umbo about half the length of the shell.

A large portion of the stratum in which these shells abound at Hordwell is a marly
bed, but I obtained a few perfect specimens from a pure siliceous sand.

5. UNIO SUBPARALLELA, Hdwards, MS. ‘lab. XX, fig. 13, a, 6.

Unio DrsuayEst1? Prestwich. Quart. Journ. Geol. Soc., 1854, p. 118.

Spec. Char. U. testa elongata, sub-quadrangulatd vel ovato-oblongd, laevigata, depressd,
valde inequilaterali ; pedi-regione brevi, rotundatd ; siphoni-regione longiore, subangulata
vel oblique truncata ; umbonibus depressis ; marginibus ventrali et dorsali subparallels.

Shell transversely elongate, or ovately oblong, smooth, depressed, very inequilateral ;
pedilateral margin rounded; siphonal region much the larger, slightly angulated or
obliquely trunculated; umbones depressed’; dorsal and ventral margins nearly parallel ;
ventral margin slightly incurved.

Length, 2 inches; height, }3ths of an inch.

Localities. Peckham (2dwards), Counter Hill, Deptford (Prestwich).

The specimen referred to U. Deshayesit by Mr. Prestwich most probably belongs to the
same species as the one here figured, but “its mutilated condition would not permit of
determination.”

In comparing our present species with the U. Wateleti (olim U. Deshayesit), the
differences appear too great to permit of their being united, and I have therefore adopted
the MS. name that was attached to Mr. Edwards’s specimen.

I am the more disposed to this separation, because I have not only the figures
and description of the French shell in the valuable work by M. Deshayes, but there is also
a specimen in the cabinet of Mr, Edwards, sent from France by the author of the species.

A shell from the “ Terrain de lignite ” in the South of France has been figured and de-
scribed by M. Matheron under the name of Unio galloprovincialis; ‘Cat. meth. et descr. des
corps organ. foss. des Bouches du Rhone,’ p. 168, Pl. 23, fig. 1, which appears from
representation very closely to resemble our own, and when the specimens themselves can
be compared, may probably be found to belong to the same species. ‘The only difference
I can observe on comparing the figure is that the umbo of the French fossil is rather the
more prominent of the two.

136 KOCENE MOLLUSCA.

6. Unto tumEscens, Hdwards, MS. ‘Tab. XX, fig. 17, a, 6.

Spec. Char. U. testa transversd, irregulariter ovata, tumidiusculd, valdé nequilaterala,
levigatd ; pedi-regione converd, siphoni-regione productd, subcuneatd ; umbonibus pro-
minulis ; lunulé sub-excavatd; cardine angusto, dente cardinali obtuso, dente laterali
- elongato.

Shell transverse, irregularly ovate or ovately wedge-shaped, somewhat tumid, very
inequilateral; pedal region rounded, siphonal region produced; umbones_ slightly
prominent and rugose ; lunule shallow ; cardinal teeth obtuse, lateral tooth elongated and
narrow.

Length, 13 inch.

Locality. Teadon Hill (Ldwards).

A few specimens corresponding to the above characters are in Mr. Edwards’s cabinet,
which he has considered to be distinct. JI am unable to refer them to any published
species.

7. Unto Vectensis, Edwards, MS. Tab. XX, fig. 15.

Spec. Char. U., testa obtusé ovata, vel ovato-rotundatd, inflaté, gibbosd, crassa, levi-
gata; umbonbus magnis, sub-prominulis; pedi-regione rotundatd, siphoni-regione
oblique truncata vel obtuse angulaté ; margine dorsali convexiusculdé ; margine ventral sub-
planata.

Shell obtusely ovate or ovately rounded, inflated, thick, smooth; beaks slightly pro-
minent ; pedilateral margin rounded, siphonilateral obliquely truncated or sloping and
rounded ; pedal region one third the length of the shell; dorsal margin convex ; ventral
margin slightly curved. '

Length, 1} inch; height, 1 inch.

Locality. Ueadon Hill, (Zdwards).

I have seen but one specimen, and this appears to be so very different in outline that,
with Mr. Edwards, I believe it to be quite distinct ; I have therefore adopted the MS.
name he has given to it. .

Tab. XX, f. 19, represents a specimen of this genus from Headon Hill which I cannot
satisfactorily assign to any of the foregoing, or to any other species known to me; at the
same time I am unwilling to consider it as entitled to a distinct specific position. I think
it possible it may be a distortion, and until better specimens be found it must remain
under the name of U. twmescens var. Headonensis. .

CORRIGENDA

For Ostrea prona, ante p. 29, read Ostrea ventilabrum, Goldf.
Ostrea pulchra, p. 30, this name should be restricted to the small shell from Bromley ; the large shell

from Reading, figured in Tab. I, is probably a distinct species, which might be called Ostrea pulcherrima.

iis. a ae af of F t eatinontl SiNY 106 Ts. 1 : J y
rr Nie andity Hlfin si L '

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.
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FIG.

1, a—/.

2, a, 0.

3, a—.

A, a, 6.
5, a, b.

TABLE XIV.

Arca biangula, page 80.

c. specimen from Barton, var. Brander, with ventral margins closed.

Edwards.
7: specimen from Bracklesham, with large gape. Mus. Edwards.
Arca planicosta, p. 81. ;
Arca appendiculata, p. 79. a

a, 6, var. duplicata. >

d—f. specimen with area of connexus plain on the pedal side.

Edwards.
Arca depressa, y. 82. Mus. Brit.
Arca modioliformis, y. 88. Mus. Edwards.

The lines denote the size of the specimens represented.

Mus.

Mus.

Lia pig

Cape PS&E
UPS SERIAL ESAS
is =StRen
Ad SS

sl 5
ee
xs

RRenea
Fe eaerersastet

i)

CH. Sowerby

Fie.

TABLE XV.

1. a, 6. Arca tumescens, page 92. Mus. Edwards.

2.
3.
A.

10.

a, 6.

2?

interrupta, p. 85.
eximia, p. 83.
impolita, py. 84.
— Pvar. Mus. Wetherell.
nitens, . 88. Mus. Edwards.
Dulwichiensis, p. 82.

29

Laekeniana, p. 80.

3)

— ; var. cylindrica. Mus. Fisher.
levigata, y. 86. Mus. Edwards.

— =; hinge greatly enlarged.
globulosa? py. 84 Mus. Edwards.

— __; hinge greatly enlarged.
tegulata, py. 90. Mus. Edwards.
Websteri, p:.92.

)
— ; outside view of a specimen with less elevated siphonal region.
— __; outside and inside views of another specimen.
Lyelli var. contorta, p. 87. Mus. Edwards.
— ,, lamellosa. te 3

tessellata, p. 91.

33

Dulwichiensis ? py. 82. Mus. Prestwich.

The lines indicate the size of the specimens.

L2:a
12.a

—
Je Yr Pas

ip ap hittt TT oo ah Si
apigi 5; |

b
(

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a

or

10.

‘TABLE XVI.

Pectunculus quasi-pulvinatus, page 100. Mus. Edwards.

pulvinatus, p. 99. 5
deletus, p. 97. 9
spissus, py. 101. :
proximus, p. 99. +

Plumsteadiensis, y. 98. Mus. Brit.

- decussatus, p. 96. Mus. Wetherell.

brevirostris, g. 95. Mus. Edwards.

globosus, . 98. Mus. Brit.

brevirostris? p. 95. Mus. Edwards.

The lines indicate the size of the specimens.

BaNas

IEG: b

SER BN

4)! ; pes

xt

- See eRTMM MN

CRC
iy Ey

if

cm
=a

Sema

‘

Fira.

TABLE XVII.

1. a—c, Leda partim-striata, page 129. Mus. Edwards.

9.
:
A.

10.
aig

Sato

a, b.

bP)

Galeottiana, p. 126. rs
costulata, p. 125.

prisca,.p. 128. .
—.; from Highgate. Mus. Wetherell.
substriata, py. 130. : Mus. Pessoal
amygdaloides, p. 125. Mus. Edwards. _ .

minima var. a. gracilis, p. 127. ,,

* B communis. ~
Cucullza decussata, p. 93. x
” Mus. Bowerbank.

. a, 6. Limopsis scalaris, py. 104. Mus. Edwards.

granulata, p. 103. *

a, 6. Pectunculus proximus, py. 99. Mus. Fisher.

The lines indicate the size of the specimens.

7.6

6

6

Le 5}
il
Q

SOP SERS i go 88

Li.

a.

ab.
B05
a, b.

sett ———C.

39

3

TABLE XVIII.

. a—c. Nucula tumescens, page 121. Mus. Edwards.

sphenoides, p. 119. - ”
Headonensis, g. 113. Be
lissa, p. 113. } %»
ampla, py. 108. 29
— var. contigua, p. 108. #
Dixoni, p. 112 =

— var. planiuscula, p.112. ,,

— var. guadrans,p. 112. ,,

minor, p. 114. $9
similis, p. 118. is

— var. trigona, p. 118. A
curvata, p. 112. sf
bisulcata, p. 109. 5
Bowerbankii, poe...
protracta, p. 117. 0»

The lines indicate the size of the specimens.

LS EVES,

A
» be
‘
te

a

i.) md 7 “2 t a
A Pol Tei]

CH WAan Ep wo ww F

ee — es ee ee
eo Oo eS

15.
16.
LY.
iS:
19:
20.
21.

apd:

it, O.

a, 6.

ty Ds

22

2?

2)

>

39

TABLE XIX.

. a, 6. Nucula prelongata, y. 116. Mus. Edwards.

sphenoides, p. 119. A
sericea, p. 120. a
prelonga, p. 115. 55
compressa, p. 110. %
Thanatiana, p. 121. Ms

consors, g. 111. Mus. Wetherell.
cardioides, y. 110. Mus, Edwards.
Wetherellii, 7. 121. Mus. Wetherell.

Leda oblata, y. 128. es
. a—c. Trigonoceelia deltoidea, y. 105. Mus. Edwards.

cancellata, ». 106. 5

Nucula subtransversa, py. 120. Mus. Fisher.
. a—c. Pectunculus decussatus, juv., y. 97. Mus. Edwards.
Modiola? subcancellata, p. 77. =

Modiola? crassistriata, p. 75. .

P consobrina, y. 76. Mus. Fisher.

? Bartonensis, py. 75. Mus. Edwards.
Deshayesiana ? p. 76. Ee
subcarinata P p. 77. 09

Nucula prelevigata, p. 123. ~ .

The lines indicate the size of the specimens.

ED. eS

va

7.

aN

SAN |

ae
(au ivi,
seri NA

TABLE XX.

Fie.
1, Nucula lissa, g. 113. Mus. Edwards.
a. a », Var. normalis, p. 113. Mus. Edwards. ‘
b. m » jfes-ransversa,. ,, a!
C. "a >» » abnormis, ,, m -
2. Leda propinqua, p. 129. 5
3. a,6. Nucula proava,p.117. Mus. Jermyn Street.
4. a,6. *,, nudata, p. 115. Mus. Edwards.
5. » sphenoides, p. 119. Be View to show tumidity and anal
region.
6. > gracilenta, py. 122. Mus. Meyer.
fp: »» consobrina, p. 122. Mus. Prestwich.
8. a. » sextans, gy. 123. Mus. Edwards.
b. id.? py. 123. Mus. Jermyn Street.
g. », Striatella, p. 123. ee
10. ss venusta, p. 122. Mus. Prestwich.
11. a, 6. Unio Solandri, py. 134. Mus. Edwards.
12. , Austenii, ». 133. Mus. Jermyn Street.
13. ,, subparallelus, py. 135. .

a. Specimen from Counter Hill pits, Deptford. Mus. Prestwich.
Peckham. Mus. Edwards.

2)

», Gibbsu, py. 1383. Mus. Jermyn Street.

is 3 ~ P var. Headonensis, p. 133. Mus. Edwards.
» Vectensis, p. 136. a
a, 6. ,, Edwardsi, 9.133. re
. a, 0. ,, tumescens, p. 135. »
Pectunculus terebratularis, py. 101. NY

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MONOGRAPH

OF

THE FOSSIL REPTILIA

CRETACEOUS FORMATIONS;

INCLUDING

SUPPLEMENT No. II.

CRETACEOUS SAUROPTERYGIA.

SUPPLEMENT No. IIL.

IGUANODON.

BY

PROFESSOR OWEN, F.RS., F.LS., F.GS., &c.

LONDON :

PRINTED FOR THE PALAZONTOGRAPHICAL SOCIETY.
1864.

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SUPPLEMENT (No. ITD)

TO THE

MONOGRAPH

OF

THE FOSSIL REPTILIA

OF THE

CRETACEOUS FORMATIONS.

OrpErR—SAUROPTERYGIA, Owen.
Genus—P Estosaurus, Conybeare.

In former Monographs and works are given descriptions of the following species
of Plesiosaurus from Cretaceous deposits :

PLESIOSAURUS CoNSTRICTUS, Owen. ‘Dixon’s Geology and Fossils of the Tertiary
and Cretaceous Formations of Sussex,’ 4to,
1850, p. 398, pl. xxxvii, figs. 6 and 7.
From Steyning Chalk-pit, Sussex.
PLEsiosAuRUS Bernarpt, Owen. Op. cit., p. 396, pl. xxxvii, figs. 8, 9. From
the Upper Chalk, Houghton Pit, near
Arundel, Sussex.
PLESIOSAURUS PACHYoMUS, Owen. Monograph, Palzontographical Society, 4to,
1851, p. 64, tabs. xx, xxi. From the Upper
Green-sand at Reach, near Cambridge.
PLESIOSAURUS LATISPINUS, Owen. ‘ Descriptive Catalogue of the Fossil Remains
of Reptilia and Pisces in the Museum of
the Royal College of Surgeons of England,’
4to, 1854, p. 63, No. 251.
|

2 FOSSIL REPTILIA OF THE

PLESIOSAURUS NEOCOMIENSIS, Cpche. ‘ Description des Fossiles du Terrain Cre-
tacé des Environs de Sainte-Croix,’ 4to,
1858—1860, par N. J. Pictet and G.
Campiche, p. 12, pl. vi.

The following are descriptions of other species of Cretaceous Plesiosauri, with
additional illustrations of already indicated species:

PLESIOSAURUS PLANUS, Owen. Vertebral Centrums, Tab. I, II, and ILI.

The cervical centrum selected for the figures 1—4, Tab. I, gives the characters
afforded by this instructive part of the vertebral column of a Plesiosaurus. ‘The flat-
ness, both of the under (fig.4) and of the terminal articular surfaces (fig.2), suggested the
name distinguishing the species, or at least the vertebrae by which alone this cretaceous
Plesiosaur has hitherto been exemplified. The costal surfaces (Tab. I, figs. 1, 2, and
4, pl) are of a narrow, oblong figure, formed, as it were, by truncation of the lower
angles of the triangular centrum, of which the apex has been more broadly removed
by the sections, leaving the neural (ib., n) and neurapophysial (ap) surfaces above.
If the borders of the costal surface have projected with a sharper definition, they
have been abraded, as, indeed, is most probable ; almost all the bones derived from
the stratum of Cambridgeshire phosphatic Green-sand being more or less rubbed or
worn, either in the original imbedding, or subsequently by the mechanical appliances
by which the phosphatic nodules are extracted. I have selected the centrum which
has been least subject to this attrition, from a large series of the present species.
Subsequent observers, who may have been favoured with entire and unworn fossil
vertebra with the main features and proportions of the Plesiosaurus planus, will
make allowance for the circumstances in which the materials for reconstructing
that species first came to hand.

What may be more certainly predicated of the costal surface is the absence of
depth and of linear horizontal bisection, both which characters are present in the
cervicals of some other Plesiosauri. The distance between the costal and neura-
pophysial surfaces is nearly three times that of the vertical diameter of the former,
and the intervening non-articular surface is smooth, and also plane or flat, sloping
upward towards the neurapophysial border, and showing no sinking or concavity
in the longitudinal direction. The neural surface, 23 lines in breadth at the
narrowest part, slightly expands towards the posterior surface of the centrum.
The neurapophysial surfaces are coextensive with the long or fore-and-aft diameter
of the centrum, and of nearly equal breadth anteriorly ; they are smooth and very
shallow, with a slightly defined, thin border, which is undulated outwardly, descend-

CRETACEOUS FORMATIONS. 3

ing lower upon the fore than upon the hind half of the centrum, and giving, in the
pair, a contour somewhat like that of a saddle; I do not, however, insist upon this
as a constant character of the cervicals of this species. In the present vertebra
one of the venous orifices is larger than the other ; but in a second, of similar size
and contiguous position, they show the usual equality. The flatness of the ter-
minal surfaces is remarkable, and betokens restriction of the movements of the
-neck of the species. On the similarly flattened under surface the venous foramina
(fig. 4, ») open nearer the anterior than the posterior border.

In a cervical vertebra, of similar size and proportions, the neurapophysial sur-
faces are more concave in the longitudinal direction. As the cervical series
approach the back the centrums increase in length, while preserving about the
same relative breadth. In the vertebra, figs. 5—7, the costal surface (p/)has risen to
the neurapophysial one (np), with which it has become confluent ; the inferior tract of
the centrum now describes a convexity between the two costal surfaces, though it
is but slight; the contour of the terminal surface accordingly presents the form of
a transversely elongate ellipse (fig. 6). The fore-and-aft contour of the under
surface is very slightly concave, almost flat. The posterior border of the costal
surface is produced, forming the beginning of a parapophysis (fig. 7). The
neurapophysial surfaces are slightly excavated, with a defined but hardly raised
border; they are undulated, smooth, with scattered foramina ; their breadth is now
one third more than their length. In the posterior cervical (fig. 7) the venous
canals on the neural surface show the same inequality as in fig. 3.

In the vertebra in which the costal surface has wholly passed upon the neur-
apophysis (fig. 10, np), and which, from the proportions of length to breadth, is to
be reckoned as coming from the beginning of the dorsal series, the sides of the
centrum are excavated under the neurapophysial surfaces; but below the excava-
tion, which is not deep, the longitudinal contour is as nearly straight as in the
antecedent vertebra.

To one of the terminal surfaces of this vertebra (fig. 11) adheres the remnant
of the lower valve of the spondyloid shell—_Dianchora striata: the living Spondylus
Gussont, which most resembles the characteristic Green-sand bivalve, dwells at
great depths in coral-beds of the Mediterranean. We may conceive, by analogy,
that the carcass of the dead Plesiosaur, sinking and decomposing in a similar
chalky manufactory, left its scattered bones to serve as the resting-places of those
bivalves of its locality and period which, like the modern smooth and spiny oysters,
anchor themselves for life after a brief locomotive period.

Towards the middle region of the back the centrums gain in vertical diameter,
and somewhat in length, with a diminution of their transverse diameter. The
concavity of the non-articular surface from before backward is still greatest near
the neurapophysis, but has less the aspect of a circumscribed depression than in

4 FOSSIL REPTILIA OF THE

the anterior vertebra. The neurapophysial pits now diminish in breadth, pre-
serving their length nearly coequal with that of the centrum itself. The terminal
articular surfaces show a slight sinuosity, feebly concave, with a less convexity at
the middle part. The under surface still retains an aspect of flatness, both from
before backward and from side to side. Most of these mid-dorsal vertebrae show
a slight difference of length in the two sides, as in figs. 9 and 14.

In one dorsal vertebra (fig. 26) a terminal articular surface, showing a porous or
spongy character, is also marked by irregular grooves converging toward the
centre, like the corresponding surface of a Cetaceous vertebra from which the
epiphysial plate had become attached. Save in this single instance, I never met
with such an appearance in a Plesiosaurian vertebra; the opposite surface is
smooth, as are both surfaces in the other vertebra of Pl. planus.

In the tail the broad and short proportions of the vertebral centrum are resumed
(figs. 16—19), but with a more marked concavity of the terminal articular surfaces,
which in one vertebra showed fine lines radiating from the centre. A broad, but
almost flattened, border extends from the terminal surface upon the side of the
centrum, joining the costal surface, and expanding to mark the place and extent
of attachment of the hzemapophyses. The diminished size and feebler impression
of the neurapophyses bespeak the reduction of the neural arch at this part of the
vertebral column. The pleurapophyses retain their independency, and were
articulated to a small subcircular surface on the upper half of the side of the
centrum ; the lower half is almost flat, and joins, at an open angle, the equally flat,
broad under surface, which is bordered, like the sides, by the deflected tract from
the articular ends. The venous canals open upon the middle of the under surface,
about four lines apart.

A few small vertebral centrums belonging to the present series, and apparently
from a similar-sized Plesiosaur, if not part of the same individual, seem to be
reduced to the simplicity of supporting only neurapophyses, and show no distinct
marks of articulations for either pleur- or hem- apophyses. The centrums are
broad, depressed, with perfectly flat terminal surfaces, and a flattened under
surface. ‘They may come from the beginning of the neck, or from the end of the
tail. I reject the latter notion, because the analogy of the terminal caudal ver-
tebre, or those in which the haemapophyses ceased to exist, in other Plesiosauri,
would lead one to expect a concavity of the articular surfaces, and a diminution
in the lateral rather than in the vertical direction, a compressed rather than a
depressed form. Assuming, then, that these vertebrae are from the beginning of
the neck, the question next arises whether pleurapophyses were wholly absent, or
whether they were so small and so feebly articulated as to leave no sign of their
attachment, at least after the degree, slight as it is, of superficial abrasion to
which the fossils have been subject. I think the latter condition may be the more

CRETACEOUS FORMATIONS. H)

probable one, although in some species of Plesiosaurus, as e.g. the present, the
‘“‘hatchet bones” or cervical ribs might only commence on the third or fourth
vertebra, beyond the coalesced atlas and axis. As a general rule, they begin on
the second cervical.

Thus, the characters of the Plesiosaurus planus are exemplified, so far as they
are shown by the vertebral centres, from all the chief regions or parts of that
column. The majority of the vertebre which have served for the comparisons
and illustrations leading to the above-given information as to the species, have
been kindly confided to me for that purpose by the Rev. Adam Sedgwick, F.R.S.;
Woodwardian Professor in the University of Cambridge.

These vertebre differ from those of all the previously described species of
Cretaceous Plesiosaurs in the proportions of breadth to length, especially in the
cervical region, and in the flatness of the terminal articular and of some other
surfaces of the centrum.

Several larger vertebrae have reached me singly, as though from a more
scattered disposition of parts of the dislocated skeleton in the phosphatic Green-
sand bed of Cambridgeshire, which agree in character with the Plestosaurus planus.

In the Plestosaurus pachyomus the centrum increases in breadth as it approaches
the back, whilst some of the dorsal vertebre offer almost the same proportions as
those in the above-described series.

But the difference in the corresponding cervical vertebre is very striking, as is
exemplified in the following comparative admeasurements.

Admvasurements of vertebral centrum :—

Anterior cervical. Middle cervical.
Pl. pachyomus. Pl. planus. Pl. pachyomus. Pl. planus.
Tn. lines. Tn. lines. Tn. lines. In. lines.
Antero-posterior diameter or length . 1 9 : 0 [1 3 2 0 ; Ls
Transverse diameter or breadth , Teno F 1 10 : Fey GE F Vk
Vertical diameter or height . : 1 9 } al f Th G F TS:

The centrum (Tab. IT, figs. 1 and 2) is of a vertebra from the posterior part of
the neck. The anterior articular surface presents a transversely elongate elliptical
form (fig. 1), contrasting with the almost circular contour of the same part in
Plesiosaurus pachyomus (Monogr. 1851, Tab. XX, fig. 2). It is very slightly, but
uniformly, concave. The neurapophysial pits (fig. 2, np), of a triangular form, and
coextensive with the fore-and-aft extent of the centrum, are divided by a neural
canal (fig. 2, x), of about 4 lines in breadth, and their lower angle, which is rounded
off, projects from the side of the centrum, which is not the case in Plestosaurus
pachyomus. The costal pit (Tab.I, fig. 1, p/) is much smaller than in Plesiosaurus

6 FOSSIL REPTILIA OF THE

pachyomus (Il. c., Tab. XX, fig. 1, pi). The under surface of the centrum is flat
from before backward, and describes a gentle uniform convexity from one costal
pit to the other.

The vertebral centrum, Tab. IT, figs. 3, 4,5, is from the base of the neck,
and from a larger individual. The. bases of the neurapophysial' pits (fig. 4,
np) have not been coextended with the increased length of the centrum, and the
apex contracts more quickly, and is extended to the upper division of the costal
pit. The breadth of the neural surface (ib., ) is the same as in the more anterior
cervical centrum (fig. 2); but the orifices of the venous canals are more con-
spicuous. Only a small part of the costal pit (ib., »2) now marks the centrum;
it projects from the side of that element, nearer its posterior surface. The
articular surfaces of the centrum (ib., fig. 3, c) are nearly flat, and slightly undu-
lating, without a central pit. ‘lhe lower orifices of the venous canal are about
two lines apart.

The centrum, Tab. II, figs. 6—9, is from the base of the neck of another and
larger individual of the Plesiosaurus planus, and, with a moderate increase of all
its dimensions, shows least that of breadth. The articular surface of the centrum
(fig. 6, c) has ashallow depression at its middle part, occupying about half the breadth
of the surface; it is flat at the circumference, and its margin, though obtuse, is
narrow and well defined. The narrow outer part of the neurapophysial tract (ib.,
fig. 9, np) has a well-defined raised border, terminating in the major part of the
costal surface, the lower half of which is much reduced in size; the interspace is
occupied by a small mass of matrix. The under surface shows a slight concavity
from before backward. The non-articular surface of the centrum is almost
smooth.

A similar and closely succeeding vertebral centrum of the same species of
Plesiosaurus is figured in Tab. III, figs. 5 and 6. It is more mutilated, and a
portion of a rib is cemented to the neural surface (fig. 6). The costal surface has
risen wholly upon the neurapophysis (np), the base of which adheres to the
centrum, and projects outward as a costal diapophysis (a). ‘This centrum is
from the fore part of the dorsal region.

The cervical centrum (Tab. III, figs. 1—4) appears to have come from the basal
third of the neck, perhaps from the beginning of that part, in which the contour
of the articular surface, expanding towards the lower part, takes on, as in the
antecedent cervicals (Tab. I, fig. 2), something of a triangular form; here, however,
the shape of the neurapophysial surfaces (np) is of a more regular triangular form
(compared with fig. 2, Tab. II) and they are connected by a narrow, slightly elevated
tract with the costal pit (p/). This articular surface begins to diminish in antero-
posterior extent, indicating a corresponding change in the shape of the shaft of
the costal rib; the terminal articular surface of the centrum has a slight central

CRETACEOUS FORMATIONS. 7

depression, of the same relative extent as in fig. 6, Tab. II. The under surface
(Tab. III, fig. 4) is almost flat, both lengthwise and transversely; the venous
outlets present the same relative position, and the non-articular surface of the
centrum shows the same degree of smoothness and flatness as in the smaller ver-
tebree (Tab. I, figs. 2, 6). The present centrum belongs to the same species of Ple-
siosaurus as those of the more regular elliptical form, and is merely indicative of a
different position in the region of the neck.

A centrum with the surface much abraded (Tab. III, fig. 8) appears to have
presented the same inferior expansion, and consequent triangular form, as fig. 1;
but in the under surface (fig. 9) the venous canals have opened into well-marked
depressions. Other differences, as in the character of the neurapophysial surfaces
(fig. 7, np), may be due to the degree of abrasion to which the present fossil has
been subject.

PLESIOSAURUS BERNARDI, Owen. Cervical Vertebre. Tab. LV.

In my ‘Monograph of the Fossil Reptilia of the Cretaceous Formations,’
Volume of the Palzontographical Society for 1851, p. 60, I characterised a species
of Plesiosaurus from a cervical vertebra then in the museum of my esteemed
friend, FrepERIc Dixon, Esq., of Worthing, under the name of Plesiosaurus
Bernardi, which vertebra was figured in Plate X VIII of the above-cited Mono-
graph. I have subsequently had the opportunity of examining several other
vertebre of a Plesiosaurus from the Green-sand of Reach, near Cambridge, which
are referable to the same species, but most of them to an individual of smaller
size, and probably of immature age.

The specimen (Tab. LV, figs. 1, 2, 3, 4) is an anterior cervical vertebra, which
agrees with the more posterior one above figured in the degree of concavity of
the articular surfaces of the centrum, in the extent of the peripheral border of
that cavity, which is convexly bevelled off (évasé”’), and in the relative position
of the neur- and pleur-apophyses; the breadth of the centrum is not so much
greater proportionally to the length; but this difference I believe to be due to the
more anterior position in the vertebral series from which the present specimen
has been derived.

The neurapophysial depression (np) is deep and smooth, encroaching further on
the convex border of the centrum at its back than at its fore part; they are
divided at the upper surface of the centrum by a neural tract (fig. 3, »), about 2
lines broad at its narrowest part. The non-articular surface of the centrum is
moderately smooth, especially at the sides between the neur- (np) and pleur- (p/)

5 FOSSIL REPTILIA OF THE

apophysial pits, (fig. 1); its vertical extent here is not quite equal to that of the
pleurapophysial pit. Thisis of an oblong oval shape, less deeply concave than the
neurapophysial pit, with a smooth surface, nearer the posterior than the anterior
surface of the vertebra, with the border slightly prominent (fig. 4, pi). The
venous foramina at the lower surface (fig. 4) are situated in depressions, divided
by a ridge-like narrow tract of the centrum. In this character, but more espe-
cially in the depth of the terminal articular surfaces, with their broad and thick
convex border, and in the position of the riblet, the present centrum is referable
to the Plesiosaurus Bernardi.
The following are dimensions of this cervical centrum:

Pl. Bernardi.

In. lines.
Antero-posterior diameter or length . ; ‘ : : 1 2
Transverse diameter or breadth : ; : 3 , 1 4
Vertical diameter or height : : ; : : : 1 a4

The centrum, Tab. IV, figs. 5 and 6, appears to have succeeded the foregoing
in the same cervical series, with, perhaps, the intervention of one or two vertebre.
It is similar in colour and mineral character, and from the same locality. It
repeats the distinctive characters of Plesiosaurus Bernardi. It indicates by a
slight obliquity the effects of posthumous pressure.

This mechanical force has distorted in a greater degree a centrum (Tab. IV,
figs. 7 and 8), doubtless from a more posterior part of the same neck. The
margins of the pleurapophysial pits are here rather more produced. The middle
of the deep concavity of the terminal surfaces is impressed by a transverse pit or
linear mark (fig. 8).

Col. Kiprianoff, of the Imperial Russian Engineer Corps, submitted to me
some plesiosaurian vertebre from the Neocomian deposits, or Green-sand, of
Kursk, in the district of Kursk, near Moscow, which offered all the characters of
the Plesiosaurus Bernardi. A cervical vertebra, intermediate in size between figs. 6
and 7, shows a partial anchylosis to the centrum of both neur- and pleur- apophyses.
The riblet was confluent to a surface near the lower part of the centrum, about
the same distance from the neurapophysis as in the first-described vertebra (fig. 1)
from the Cambridge Green-sand. The under surface was ridged or pinched up, —
as it were, between the venous foramina, each of which was also situated in a
depression between the median ridge and the base of the riblet. This element
expanded, and its posterior angle was produced backward. The following were
the dimensions of the centrum of this vertebra :

CRETACEOUS FORMATIONS. 9

Plesiosaurus Bernardi.

In. lines.
Antero-posterior diameter or length . : ° . : : ° Les
Transverse diameter or breadth é : : : ; : : IF
Vertical diameter or height ; : : : : ; : : yen

In a more posterior cervical vertebra, from the same Russian locality, the
terminal articular surfaces are deeper towards the centre, with the out-turned or
“évasé” borders very thick. The base of the neurapophysis was here also par-
tially anchylosed, and the rib more completely so; it presented a rhomboid form,
being inclined backward as well as outward, with the anterior angle rounded, and
the posterior one produced. The inferior medial ridge was well marked. The
breadth of the centrum was relatively greater than in the preceding vertebra.

In the vertebra from the Cambridge Green-sand (Tab. IV, figs. 9 and 10), which
have succeeded one another from about the same part of the neck, anchylosis of
the pleurapophysis has not been completed ; but that of the neurapophysis (np) has
been so to a degree sufficient for preserving their base in connection with the
centrum, although the summit has undergone fracture. The line of suture is,
however, very distinct.

The terminal surface of the centrum presents the same degree of concavity, with
aslight central horizontal linear depression, Tab. V, fig. 1,as shown in Tab. IV, fig. 8.
The base of the neurapophysis (np) extends to the anterior margin of the centrum, but
not quite to the posterior one. The outer surface of the neurapophysis presents a
low obtuse ridge or rising, extending from near the infero-posterior angle to the
outer side of the prezygapophysis (Tab. IV, figs. 9,10, 11, z) ; the aspect of the arti-
cular surface of this process is obliquely upward and inward. The posterior border
of the neurapophysis is thicker, or more obtuse, than the anterior one; the
internal surface is smooth and even. Rather less than the vertical diameter of
the pleurapophysial pit (figs. 10 and 11, pi) intervenes between it and the base of
the neurapophysis (np). The inferior surface of the centrum presents the ridge
between the two depressions into which the venous vertical canals open.

In the vertebra (Tab. IV, fig. 11), from a more posterior part of the neck, or
from a larger Plesiosaurus, a greater proportion of the neural arch (np) is preserved,
partially anchylosed to the centrum; the sides are strengthened by the same
oblique thickening, extending to the prezygapophysis (z); this is larger than the
postzygapophysis (z’), and the breadth of the arch across the prezygapophyses is
nearly twice that across the posterior pair (Tab. V, fig. 6). The neural spine
appears to have been a thin plate ; its base (Tab. V, fig. 6) extends from the notch
between the postzygapophyses (-) to within 3 lines of that between the prezyga-
pophyses (z). This vertebra has been compressed laterally, and rather obliquely,
by posthumous pressure; yet under such general support that the neural arch,

2

10 FOSSIL REPTILIA OF THE

though apparently narrowed from side to side is not broken; the neural canal
(Tab. V, fig. 2, x) presents a vertical diameter of 11 lines, and a transverse diameter
of 7 lines. The costal depression (Tab. IV, fig. 11, »7) extends nearer to the
posterior than to the anterior surface of the centrum. The articular surfaces of
the centrum show the characteristic depth of the concavity, but with relatively
less thick obtuse borders, Tab. V, fig. 2.

The dimensions of this vertebra are:

In. lines.

Length of centrum . : * , ’ ; F ; : z 1 7
Height of ditto : : , ee ie
Breadth of hinder surface of ditto : : : +
From base of neurapophysis to end of postzygapophysis 2 3
From end of pre- to that of postzygapophyses ye
Breadth of neural arch across prezygapophyses . 2136

” » 9 99 99 postzygapophyses ee |
Antero-posterior extent of base of neural spine Bi

The vertebra, Tab. V, figs. 3, 4, and 5, appears to have come from the middle
of the neck of an older and larger Plesiosaurus, and it displays, in a striking degree, —
the characteristics of that part of the Plestosaurus Bernardi.

The depth of the concavity of the terminal surfaces of the centrum is almost
ichthyosaurian ; the breadth of the convex border of each cavity is extreme, and
is equally divided between the smoother articular surface continuous with that
of the concavity, and the surface roughened by fine concentric linear impressions,
forming the outer part of the border, and indicative of the strong circular liga-
ments which tied the vertebre together.

Anchylosis of both neur- and pleur-apophyses is here complete; and the
missing parts of both vertebral elements have been broken off. The neurapo-
physial suture is, however, traceable; and the characteristic distance between it
and the cervical rib is thus exemplified. The rising between the vascular depressions
on the under part of the centrum (fig. 4) is broader and less ridge-like than in
the more advanced vertebre of the neck. In this vertebra, in relation to its more
posterior position in the neck, the transverse diameter has increased upon the lon-
gitudinal one, as is shown in the following admeasurements :

In. lines.
Length of centrum . : : : : : : , : : re 9
Breadth of ditto, posterior surface. : . : . ; : AS &)

The riblet, at its fractured surface (fig. 5, pi), shows an antero-posterior
diameter of 10 lines, a vertical diameter of 5 lines.

Valves of the fry, or young, of a species of Plicatula (?) adhere to this fossil,
to which they attached themselves at the period when the cretaceous beds,

CRETACEOUS FORMATIONS. ll

receiving the carcases of the dead Plesivsauri, were still in process of formation,
where now the dry land of Cambridgeshire has risen.

In a dorsal vertebra of this species, from the Neocomian deposits of Kursk, the
terminal articular surfaces of the centrum were less concave than in the neck, and
the lower surface was obscurely or very obtusely ridged. This vertebra measured
in :—

In. lines.
Length . : : - : : ; . - : : Ltd
Breadth, anterior surface of centrum . : ; : ; i . 22.6
- posterior surface of centrum . : : : : : : Hh fe

A caudal vertebra of the same species of Plesiosaurus, from the same forma-
tion and locality, showed the hzemapophysial surface best marked on the posterior
border of the centrum; they were each subtriangular in shape, 6 lines in long
diameter, and 1 inch apart. The pleurapophyses were anchylosed to the upper
part of the centrum, or over the base of the neurapophysis; but the sutural line
of juncture could be traced. ‘The terminal surfaces of the centrum were mode-
rately and gradually concave, but with the broad obtuse border. The lower
surface was nearly flat and subquadrate, with only a feeble indication of a rising
between two small venous foramina. The length of this vertebra was 1 inch 7
lines, the breadth of the centrum was 2 inches 3 lines.

I have introduced the above notices of the vertebre of the Plestosaurus Ber-
nardi from the Green-sand beds of the neighbourhood of Moscow, in illustration of
the geographical range of the species at the period of geological time in which
it existed; this period extending from the “ neocomian” to the “ upper chalk” of
the Cretaceous series. In the following section will be found a similar illustration
of the geographical range of another Cretaceous Plesiosaur.

PLESIOSAURUS NEOCOMIENSIS, Campiche. Cervical and dorsal vertebre ; humerus
and femur. Plate VI.

Professor Pictet and Dr. Campiche, in their excellent ‘Description des
Fossiles du Terrain Crétacé des Environs de Sainte-Croix,’ 4to, 1858—1860, have
described and figured three centrums of a dorsal vertebra of a Plesiosaurus, to
which Dr. Campiche has attached the name neocomiensis, inasmuch as these fossils
were derived from the lower neocomian or “ valanginian’’ beds of the Cretaceous
deposits described in the above work. And this name, although there be other
neocomian Plesiosaurs, and there may be many, I retain for a species, richly
illustrated, from the Upper Green-sand deposits of Cambridgeshire, and which
I believe to be identical with Dr. Campiche’s.

12 FOSSIL REPTILIA OF THE

Dorsal centrums are usually the least significant of specific characters, owing
to the limitation of the articular surfaces to the neurapophysial and terminal ones,
and also owing to a resumption, more or less, in the dorsal region of the more
common proportions of the centrum, when this is departed from, either in excess
of breadth, depth, or shortness, in the cervical region.

Dr. Campiche’s description is so minute and exact that the correspondence of
the dorsal centrum (Tab. VI, figs. 9, 10, 11) with the characters expressed at p. 43,
op. cit., and shown in “ Plate VI” of that work, will be found to justify the specific
approximation. The centrum of Pl. neocomiensis is “a little broader than high, so
that the articular surfaces form nearly a transverse, very slightly elongated,
ellipse ; the shape would be even better expressed by a circle, of which the upper
part was flattened and subtruncate (see fig. 18).”* ‘“ The length is sensibly inferior
to the two other dimensions ; the sides are strongly and gradually excavated, so that
when the vertebra is viewed from above,” (as in fig. 11, Tab. V1) op. cit., “its middle
part is much narrower than its articular surfaces. The inferior region, corresponding
to the medial line of the body, is more feebly excavated.| ‘The two large and deep
neurapophysial pits are slightly arched inwardly, and are two and a half times as
long as they are large; but the most significant character is the slight concavity
of the terminal surfaces, with their middle part feebly raised into an irregular
protuberance.”

In the larger of the dorsal centrums from the Swiss Neocomian, measuring
2 inches 7 lines in transverse diameter, the median rising is 10 lines in diameter, but
not more prominent than the more circumscribed rising in Tab.VI, fig. 10 of the pre-
sent Monograph. In the smaller Swiss centrum (Plate VL, fig. 2 of op. cit.) the central
eminence is broader and lower than in the nearly equal-sized centrum (Tab. VI, fig.
10) of the present Monograph ; nevertheless, I am inclined to think that the mam-
millate character of the terminal articular surfaces shown in the cervical vertebra
may, like other characteristic modifications, be less strongly manifested in the dorsal
vertebrz, or in some of the dorsal vertebrz of the same individual ; and, therefore,
I supersede my MNS. denomination of Plesiosaurus mamillatus, under which I dis-
tinguished those vertebre from the Cambridge Green-sand, when first obtained

* « Un peu plus larges qu’ils ne sont hauts, en sorte, que leurs faces articulaires forment, 4 peu pres, une
ellipse transverse trés peu allongée. Leur forme serait méme mieux exprimée par un cercle dont la partie
supérieure serait aplatie et subtronquée.”—Op. cit., p. 43,

+ “La longeur est sensiblement inférieure aux deux autres dimensions. Les flanes sont fortement et
graduellement excavés, en sorte que, lorsqu’on regarde la vertébre au dessus, sa partie médiane est beau-
coup plus étroite que les faces articulaires.”” ‘‘ La région inférieure qui correspond 4 la ligne médiane des
corps est beaucoup plus faiblement infléchée, A la face supérieure, on voit deux grandes et profondes im-
pressions, correspondant a l’insertion des neurapophyses ou lames tectrices. Elles sont un peu arquees
en dedans, deux fois et demie aussi longues que larges, les faces articulaires sont legérement concaves, avec
leur milieu faiblement relevé en une protubérance irréguliére.’””—Op. cit., p. 43.

CRETACEOUS FORMATIONS. 13

for the British Museum, and adopt Mr. Campiche’s name, which has the priority
of publication, under the conviction of the specific identity of the vertebra from
the two localities.

All the mamillate vertebree I have yet seen from the Cambridge Green-sand
indicate a Plesiosaurus not larger than that represented by the smallest of the
dorsal centrums from St. Croix.

The cervical vertebra (Tab. VI, figs. 1—4) shows a greater proportional trans-
verse dimension of the centrum than in the vertebra from the dorsal region (ib.,
figs. 9, 10), the sides of the centrum are less concave (compare fig. 4 with fig. 11) ;
on the inferior surface the shallow impressions into which the vertical venous
canals open, are divided by a narrow ridge-like tract (ib., fig. 4). The neurapo-
physial depressions (figs. 1 and 3, np) are broader than in the dorsal centrum, are
of a triangular form, and, as the intervening neural tract is of equal breadth (ib.,
fig. 3), it is relatively larger than in the dorsal vertebra (ib., fig. 11); the venous
foramina in this tract (fig. 3,2) are also wider apart. The costal surface (fig. 1, pl)
is large in proportion to the centrum, well defined, but not deep; transversely
elliptic ; 9 lines in longitudinal by 6 lines in vertical diameter, and 3 lines distant
from the apex of the neurapophysial pit (np): it is situated rather nearer the pos-
terior than the anterior part of the centrum, and its margin slightly projects from
the level of the non-articular surface of the centrum; the distance between the
inferior borders of the two costal pits (fig. 4, p/) is 10 lines. ‘The terminal articular
surface (fig. 2) is less concave than in the Plesiosaurus Bernardi, and although
obtuse and convex at the circumference, is less thick or tumid there ; but the con-
spicuous and chief distinction is the well-defined mammillary eminence in the centre
of each of the terminal concavities. The following are dimensions of this centrum:

In. lines.
Length . ‘ : : ; : . : : ; : : el
Breadth . ; : ; ‘ ; : i , ‘ : i i 5
Depth ‘ ; : , : : : ; : : . : i 4

Figures 5 and 6 represent a vertebra of apparently the same individual from
the base of the neck, where the costal surface (Tab. VI, fig. 5, p?) has almost wholly
ascended from the centrum upon the neurapophysis (np), and is more prominent
than in the average cervical vertebreez. The under surface of the vertebra is not
excavated or ridged, and is very slightly concave lengthwise; it resembles that of
the average dorsal vertebre. ‘The mamillate character of the terminal articular
surface is as well marked as in the average cervical vertebra.

Figures 7 and 8 are of a posterior cervical vertebra of another individual, from
a different locality, in which the centrum is relatively shorter than in the two fore-

14 FOSSIL REPTILIA OF THE

going vertebre ; in other respects the characters closely accord with those of the
posterior cervical centrum (figs. 5 and 6), and I regard the present as indicating
a mere variety in the proportions of the centrum, which is also less than it
appears in the plate, on account of the abrasion of the circumference of one of
the terminal articular surfaces. ;

The dimensions of the restored centrum are:

In. lines.
Length. : ; 3 : : 3 : : : : : 1 3
Breadth of posterior surface : ‘ : : : - : : Sa
Height. ; : : : 3 f ; us 2 ‘ it 136

The dorsal centrum (figs. 9, 10, 11) exhibits the characters already specified
in the comparison of it with the type-vertebra of Dr. Campiche’s species; the
chief or sole difference is the more circumscribed and smaller circumference of
the central mamilla of the terminal articular surface; the neurapophysial pits
have undergone the change of form and proportions which brings them to the
same pattern as in the dorsal vertebra figured in the ‘ Paléontologie Suisse,’
loc. cit.

In the locality whence the specimens (figs. 1—6, 9—11, Tab. VI) were
exhumed, some portions of limb-bones were obtained of a Plesiosaurus of cor-
responding size, of which I select for figuring a left femur (fig. 12) and the lower
two thirds of a left humerus (fig.13)._ The outline of asection through the broadest
part of the distal and of the humerus is given to the left of fig. 13, to exemplify the
difference in the proportions of this bone from the humerus of the Plesiosaurus
pachyomus from deposits of the same age. The outline connected by dots with
fig. 12 represents a section of the proximal end of that femur. I think it
most probable that both these bones appertain to the Plesiosaurus neocomiensis
of Campiche.

PLESIOSAURUS LATISPINUS, Owen. Cervical vertebrae, Tab. VII; cervical and dorsal
vertebre, Tab. VIII; ilium and _ coracoid,
Tab. IX.

This species was founded on the characters of the two cervical vertebre figured
in Tabs. VII and VIII. They form part of a scattered series of about a dozen
vertebre, with ribs, scapula, portions of the coracoid bones (Tab. IX, fig. 2), an
ilium (Tab. IX, fig. 1), and a few other parts of the skeleton, included in a rock of
the “Shanklin-sand” or Lower Green-sand series, from the so-called “ Iguanodon
Quarry,’ at Maidstone, Kent, where they were observed and partially wrought out

CRETACEOUS FORMATIONS. 15

by the proprietor, Witnt1AmM Harpine BensteEp, Esq., to whom the earlier discovery
of remains of an Iguanodon in the same locality and formation, is due.*

My first knowledge of these remains was obtained from plaster casts of the two
most complete vertebree which were transmitted to me by Mr. Bensted for deter-
mination of the species in 1853, which casts were afterwards presented by Mr.
Bensted to the Museum of the Royal College of Surgeons.+ ‘The original of these
casts, with the other portions of the skeleton discovered by Mr. Binsted, have since
been purchased by the Trustees of the British Museum.

From the ‘Plesiosaurus pachyomus, Owen, of the Upper Green-sand of Cambridge-
shire, the present species differs in the greater relative length and breadth of the
centrum in proportion to its height, in the smaller relative size of the costal surface,
its greater prominence, and inferior position upon the side of the centrum, where
it is supported by a low parapophysis (compare Tab. VII with Tab. XX, tom. cit.,
Monogr. Cretaceous Reptiles). In that plate are represented the centrums of
three cervical vertebre of the Plesiosaurus pachyomus ; one (fig. 1) giving the charac-
ters of the ordinary or more numerous cervicals; a second (fig. 2) showing the
commencement of the rise of the costal surface, and the development of the
vertical ridge connecting it with the neurapophysial surface ; a third (fig. 3) showing
the junction of the two articular surfaces indicative of the passage of part of the
head of the pleurapophysis upon the base of the neurapophysis.

The following are dimensions of an ordinary cervical centrum of the two species :

Plesiosaurus latispinus _Plesiosaurus pachyomus.

In. lines, In. lines.
Length : : : : : : ; F 2° § : le Siri
Breadth : 3 70 es;
Height : ° Ja) 4st ; : 2He06 Bis ws:
Fore-and-aft diameter of the costal surface og) ty 4

The borders of the terminal articular surface are thinner and more defined in
Plestosaurus latispinus than in Plesiosaurus pachyomus. The costal surface (Tab. VII,
fig. 1, pl) is longitudinally coextensive, in Plestosaurus latispinus, with little
more than one third of the fore-and-aft extent of the centrum. In Plesiosaurus
pachyomus it is coextensive with two thirds of the same extent. In Plestosaurus
latispinus it is situated so low down as, in a direct side view, to mask part of the in-
ferior contour of the centrum. In Plesiosaurus pachyomus it allows the whole of the
lower contour to be seen in the same side view. In Plesiosaurus latispinus more than the
vertical diameter of the costal surface, by one fifth or one sixth, intervenes between it

* See ‘Monograph on the Fossil Reptilia of the Cretaceous Formations,’ volume of the Paleonto-
graphical Society for 1851, p. 105.

+ See ‘ Descriptive Catalogue of the Fossil Reptilia and Pisces,’ 4to, p. 63, No, 251.

16 FOSSIL REPTILIA OF THE

and the neurapophysial surface. The terminal articular surface (ib., fig. 3) is very
little concave, sububundulating, with a transversely elliptical, very shallow, central
depression. The sides of the centrum are slightly concave, the under surface more
feebly so, and it is not longitudinally ridged. The venous foramina are divided
by a transversely convex tract of 6 lines extent (Tab. VII, fig. 2). The whole of the
non-articular surface is smooth. The costal surfaces (fig. 1, pz) are almost wholly
situated in the posterior half of the centrum. ‘The neural arch and spine, by rare
fortune, are preserved in the present instance (fig. 1) in natural articulation with
the centrum. The sutural line describes a subangular convexity downwards, and
with the lowest part (np) nearer the anterior surface of the centrum. The neurapo-
physis, as it rises, has its fore-and-aft extent decreased by emarginations, of which
the posterior one is the longest ; this extent then increases by the development of
the zygapophyses, of which the posterior (’) is most raised ; but the anterior (2) most
produced. The spinous process (ns) is remarkable for its antero-posterior extent,
preserving the same width to its truncated summit; it thus presents a subquadrate
figure, and is inclined rather forward ; it arises from the entire fore-and-aft extent
of the median line of the neural arch. The total height of the vertebra, from the
under part of the centrum to the summit of the spine, is 9 inches; the height of
the spine itself is 45 inches; the antero-posterior diameter is 25 inches. The
articular surfaces of the prezygapophyses (2) look upward and a little inward ;
those of the postzygapophyses (z) look in the opposite direction.

Two other cervical vertebre, with the characters above defined, are preserved in
the slabs of stone exhibiting the parts of the skeleton of the same individual Plesiosaur.
In the last cervical vertebra(Tab. VIII, figs. 1 and 2) the costal surface is of large size,
especially in the vertical direction, and is supported in its lower third upon a parapo-
physis (p), which has now risen to the middle of the side of the centrum, and has come
in contact with a diapophysial development (a) of the side of the neural arch, support-
ing the upper two thirds of the costal surface. ‘Together they form a thick and deep
outstanding process, 2 inches in vertical by 1 inch 3 lines in transverse extent, with
the articular surface for the expanded head of the rib looking outward and rather
downward, fig. 2. The terminal articular surface of the centrum (fig. 2, ¢) presents
a sharper or better defined border than that of the normal cervical vertebra
(Tab. VII, fig. 3) ; it is 3 inches 6 lines in transverse, and 2 inches 8 lines in vertical
diameter, almost an ellipse in figure, but with the lower curve greater or deeper
than the upper one; the central shallow depression is continued in the present
vertebra, of similar proportions and contour as in the foregoing normal cervical
vertebra. The neural arch has become anchylosed to the centrum, but the
greater part is broken away. The neural canal (n) is subcircular, 8 lines in
diameter.

CRETACEOUS FORMATIONS. 17

In the dorsal region, where the rib is supported wholly by a diapophysis
developed from the platform of the neural arch (np), the centrum has assumed the
ordinary subcircular shape, at least at its articular ends (Tab. VIII, fig. 3). The
surface is very slightly and uniformly concave in most, with a slight central
depression occupying about one third of the vertical diameter of the surface; but
in some, as in fig. 3, there is hardly any trace of the median depression. The
sides of the centrum are rather more concave lengthwise than in the cervical
series, but least so at the lower part. |

The following are dimensions of the dorsal vertebra:

Plesiosaurus latissimus,

In. lines.
Length of centrum 2 6
Breadth of ditto, at articular aa QF Th
Breadth of ditto, at the middle 2 4
Height of ditto, at articular end Z 10
Vertical diameter of outlet of neural canal O° 10

The following are admeasurements of a dorsal vertebra, having a greater
proportion of the neural arch preserved :

In. lines.

Length of centrum . 2 8
Depth of terminal surface Ziel O
Breadth of ditto 3
Breadth of the middle of the bent 2 5
From the under part of the centrum to the upper pail of ite

diapophysis : 4 3
From ditto to summit of sata spine . 0
Fore-and-aft extent of neural spine . : : . 4 : : 2 3

The chief changes observed in the middle dorsal vertebre are the almost
circular contour of the articular ends of the centrum, and the minor antero-
posterior breadth of the neural spine.

Of one of the dorsal ribs an extent of fourteen inches in length is preserved ; it
shows two flexures; the first and shortest is concave upward, the rest convex
upward and outward, for half the extent of the rib, the rest being straight. Many
smaller parts of the ribs are scattered about the block of matrix.

The coracoids exhibit the proportional size, and broad expanse, characteristic
of the genus; they are in too fractured and mutilated a state to serve for deter-
mination of any specific characters. One of the largest portions is figured in
Tab. IX, fig. 2.

3

18 FOSSIL REPTILIA OF THE CRETACEOUS FORMATIONS.

The ilium, five inches in length, and one inch in breadth at the middle, expands
* to both extremities by outgrowth from one and the same margin, which is thus
made concave, whilst the opposite margin is nearly straight (‘Tab. 1X, fig. 1). The
upper expanded end is obliquely truncate. The lower one shows the articular
facets contributed to the acetabulum, and to the other pelvic: bones entering into
the formations of that articular cavity.

SUPPLEMENT (No. ITD

TO THE

MONOGRAPH

ON THE

eeu A NO DON:

Mandible of a young Iguanodon (Tab. X).

I nave been favoured by the Rev. W. Fox, M.A., Rector of Brixton, Isle of
Wigbt, with the inspection of a portion of the left mandibular ramus of an
Iguanodon (Tab. X, figs. 1—4), including the entire series of alveoli. These are
fifteen in number, and are clearly indicated by the angular risings of the outer
alveolar wall, forming the intervals or divisions of the alveoli (fig. 4, 1—15).
Between the summits of the angular processes the upper margin of the socket is
deeply concave, and, the sockets being contiguous, a strongly marked crenate
character is given to the border of the outer alveolar wall.

The longitudinal extent of the alveolar portion of the present ramus is 4 inches
3 lines. About an inch of the edentulous fore part of the ramus is preserved, but
the symphysial end is broken away. At the opposite part of the fragment it has
broken off, about three lines behind the last alveolus, from the rest of the jaw.

The teeth which occupied the alveolar depressions of the outer wall are gone.
The germs of three successional teeth (ib., figs. 1 and 2, 6, 12, 14) are preserved. The
summit of the hindmost (14) has risen to the level of the opening of the antepenulti-
mate socket ; the next in advance (12) has risen half way towards the outlet of the
twelfth socket ; the crown of the third just shows at the bottom of the sixth socket,
counting from before backward. Each of these germ-teeth has the inner surface
exposed of the summit of the crown, the anterior one showing the least proportion
of the tooth. The primary longitudinal ridge (fig. 5, a) and the marginal serra-
tions (cc') are boldly and beautifully marked on the dark, lustrous enamel, the
serrations being continued by grooves, some way upon the exposed inner side of

20 SUPPLEMENT TO THE

the crown. The primary ridge more equally divides the summit of the crown
here seen than in the part below, but the greater extent of the anterior area (c) is
appreciable ; the secondary longitudinal ridge (4) is discernible in both the anterior
and posterior arez of the crown, in the last two germs (fig. 1, 12, 14, and fig. 6). So
much of the crown as appears in these teeth shows greater fore-and-aft breadth than
the socket they would rise into, or rather than the socket of their predecessor, and
the difference of breadth is so much greater in the basal part of the crown as to
suggest much growth of the jaw in the progress of the germ to the state of a fully
developed tooth in place. We thus obtain evidence of the immaturity of the
specimen, and that it has not belonged to a distinct and diminutive species of
Iguanodon.

Like all reptiles, the [guanodon shed and renewed its teeth many times during
the course of life; the new following the old teeth vertically, and being, therefore,
in the growing animal, of a larger size than those they were about to displace.
With the shedding of the deciduous teeth there was more or less absorption of
their sockets, and with the rise of the successional teeth there was a concomitant
formation of suitable, and, therefore, larger sockets.

In the Crocodile the number of teeth, or of sockets of one and the same set of
teeth, does not vary with age, according to the observations of Cuvier.* Each
tooth succeeds its forebear vertically, and none are added to the series, as in
mammalia, from behind.

I believe myself able now to adduce evidence that the Iguanodon added this
mammalian mode of succession to some other characters, which have been in pre-
vious Monographs pointed out, exemplifying its greater resemblance to the
warm-blooded beasts than any existing form of reptile manifests.

The mandible of the young Iguanodon here described shows at the utmost
fifteen sockets in the unquestionably entire series, occupying a longitudinal extent
of four inches and a quarter. The mandible of the somewhat older Iguanodon,
from the Wealden of Stammerham, Sussex, described and figured in my Mono-
graph (1855) Tabs. X and XI, shows eighteen alveoli, occupying a longitudinal
extent of six inches.

The mandible of the Iguanodon from the Wealden of Tilgate, Sussex, figured
by Mantell in the ‘ Philosophical Transactions’ for 1848, Pl. xvii, seems to
have had at least twenty alveoli in a longitudinal extent of fourteen inches. The
back part of the series is too much mutilated for precisely showing the divisions

* «Tes dents offrent plusieurs remarques intéressantes dans le crocodile. La premitre, c’est
que leur nombre ne change point avec l’age. Le crocodile qui sort de |’ceuf les a autant que celui de vingt
pieds de long.’’—-‘‘Je me suis assuré de ce fait dans une serie de huit tétes croissant en grandeur, depuis
un pouce jusqu’a deux pieds.’’ Cuvier, ‘Ossemens Fossiles,’ 4to, tom. vy, pt. ii (1825), p. 90.

MONOGRAPH OF THE IGUANODON. 21

of the sockets ; but the number, eighteen, which I originally estimated, from the
figures of the fossil in the ‘Philosophical Transactions’ is clearly below the
number which may be estimated in the alveolar tract of the original specimen
now in the British Museum.

From the foregoing facts, therefore, it may be concluded that the Iguanodon,
in the progress of growth, from the period at which the dentigerous part of each
ramus of the mandible is four inches in length to that in which the same part is
fourteen inches in length, acquires four or five additional teeth in each series, which
from the rapidly decreasing depth of the three or four hindmost alveoli, I infer
to be developed, like the true molars of mammals, in new and distinct alveoli
behind those in place.

My obliging correspondent, Mr. Fox, who had been struck with the inferiority
of number of the alveoli in his small specimen, compared with the indication
of them in Mantell’s plate of the larger jaw from Tilgate, supposed that it might
indicate a distinction of species; but the whole evidence of the Iguanodon’s
mandibular structure, including the intermediate-sized specimen obtained by
Mr. Holmes from Stammerham, appears to me to show only difference of age,
and to bring to light a new and important characteristic of the dentition of the
large extinct Herbivorous Reptile.

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TAB. I.

Plesiosaurus planus, nat. size.

. Side view of centrum of an anterior cervical vertebra.

. Front view of ditto.

. Upper view of ditto.

. Under view of ditto.

. Side view of centrum of a posterior cervical vertebra.

. Front view of ditto.

. Upper view of ditto.

. Side view of centrum of a posterior cervical vertebra.

. Under view of the same centrum as fig. 7.

. Side view of centrum of the first dorsal vertebra.

. Front view of ditto, with portion of the lower valve of Dianchora striata
attached.

. Side view of centrum of a dorsal vertebra.

= ky
ES as ee eS, I Se de

—
—

—
bo

. Front view of ditto.

es
e Ow

. Upper view of ditto.
. Lower view of ditto.
. Side view of centrum of anterior caudal vertebra.

— —
oy Or

. Front view of ditto.

ee
Go wn

. Upper view of ditto.
. Under view of ditto. i.
. Front view of centrum of third (?) cervical vertebra.

Ww NW =
[p= te) is)

. Upper view of ditto.
. Side view of ditto.
. Side view of centrum of fourth (?) cervical vertebra.

oe)
Ww bo

. Front view of ditto.

Li )
AS

. Under view of ditto.
26. Front view of centrum of a dorsal vertebra, with grooved articular surface.

i)
On

From the Upper Green-sand near Cambridge. In the Woodwardian and

British Museums.

J.Dinkel del. et ith

PLESIOSAURUS PLANUS.

TAB. IL.
Plesiosaurus planus, nat. size.

1. Front view of centrum of posterior cervical vertebra.
. Upper view of ditto.

. Front view of centrum of posterior cervical vertebra of a larger individual.

. Upper view of ditto.

. Front view of centrum of posterior cervical vertebra of a larger individual.

. Under view of ditto. ;

2

3

4

5. Side view of ditto.
6

7

8. Side view of ditto.
9. Upper view of ditto.

From the Upper Green-sand near Cambridge. In the Woodwardian and
British Museums. ~

TIT.

J.Dinkel del et lith

WWest imp.

PLESIOSAURUS PLANUS.

TAB. ITI.

Plesiosaurus planus, nat. size.

1. Front view of a centrum from near the posterior part of the neck.

. Side view of ditto.

. Upper view of ditto.

. Front view of centrum of posterior cervical vertebra.

2
3
4. Under view of ditto.
5
6. Upper view of ditto.
7

. Upper view of anterior cervical vertebra, from an individual much larger than

the one to which the vertebra, Tab. I, figs. 1—4, belonged.
8. Front view of ditto, with the surface abraded. |

9. Under view of ditto.

From the Upper Green-sand, near Cambridge. In the Woodwardian and
British Museums.

TMT.

te

Seair

asa

PLESIOSAURUS PLANUS: figs Tae 7.

2, Var. trigonalis.

ae Ais archi :

a.

“hk

ey

« %
i

Gre, & -co +

iA:

TABETY.

Plesiosaurus Bernardi, nat. size.

. Side view of centrum of an anterior cervical vertebra.
. Front view of ditto.

. Upper view of ditto.

Under view of ditto.

. Side view of centrum of a cervical vertebra.
. Front view of ditto.

. Side view of centrum of cervical vertebra, slightly distorted by posthumous

pressure.

. Front view of ditto. |
. Side view of centrum and base of neural arch of cervical vertebra.

10.

Side view of centrum and base of neural arch of a succeeding cervical
vertebra.
Side view of centrum and neural arch, minus spine, of a cervical vertebra of a

‘larger individual.

From the Upper Green-sand, near Cambridge. In the British Museum.

TRING

Dmkel del. et lth

PLESIOSAURUS BERNARDI

St) ter) ates ies es

TAD V.

Plesiosaurus Bernard, nat. size.

. Front view of centrum and neurapophyses of cervical vertebra.
. Back view of centrum and neural arch, minus spine, of cervical vertebra.

. Front view of centrum and anchylosed base of neural arch of cervical vertebra

of a larger individual.

. Under view of ditto.
. Side view of ditto.
. Upper view of the vertebra, fig. 2.

. Under view of centrum of cervical vertebra, slightly distorted by posthumous

' pressure.

From the Upper Green-sand, near Cambridge. In the British Museum.

J.Dmnkel del. et hth.

PLESIOSAURUS BERNARDI

W.West imp.

AY

TAB. VI.

Plestosaurus neoconuensis, Cpche., nat. size.

ee
mE

. Side view of centrum of cervical vertebra.

Front view of ditto.

Upper view of ditto.

Under view of ditto.

. Side view of centrum of a posterior cervical vertebra.
. Front view of ditto.

Side view of centrum of last cervical vertebra.

Front view of Hitto.

. Side view of centrum of a dorsal vertebra.

erie. OS ey Pepe ce to

—

. Front view of ditto.

=
—

. Upper view of ditto.

—
bo

. Femur, side view, with outline of distal end.

—
ww

Lower part of humerus, with sectional contour of the expanded portion.

From the Upper Green-sand, near Cambridge. In the Woodwardian and

British Museums.

EVE

J.Dinkel del. et ltth

W.West amp

PLESIOSAURUS NEOCOMIENSIS. Cpche

yA
:

é ee.

7.

RA eet

ites
A cay

ee
SG ao Rey v¢ “1
Paar t

‘4

pat

“~

TAB. VII.

Plesiosaurus latispimus, nat. size.
Fig.
1. Side view of centrum of cervical vertebra.
2. Under view of ditto.

3. Front view of ditto.

Discovered by Mr. W. H. Bensted in the Lower Green-sand of the Iguanodon
Quarry, near Maidstone ; now in the British Museum.

PLESIOSAURUS LATISPINUS.

TAB. VIII.

Plesiosaurus latispimus, nat. size.

Fig.
1. Side view of centrum and part of anchylosed neural arch of a posterior cervical

vertebra.
2. Back view of ditto.

3. Front view of centrum and anchylosed neural arch, mutilated, of a dorsal

vertebra.

Discovered by Mr. W. H. Bensted in the Lower Green-sand of the Iguanodon
Quarry, near Maidstone ; now in the British Museum.

L.VII/

W.West imp

J Dinkel del et ith

a

IOSAURUS LATI

h

1a
~

Pee

TAB. IX.

Plesiosaurus latispinus, nat. size.

Fig.
1. Right iliac bone.

2. Portion of left coracoid bone.

Discovered by Mr. W.H. Bensted in the Lower Green-sand of the [guanodon
Quarry; now in the British Museum.

LEX:

BY

,

ae
as

W West imp

J Dinkcel del et Irth

ESIOSAURUS LATISPINUS

Lhe

bia

wr Aa

TAB. X.

Lguanodon Mantelhi, nat. size.

Fig.
1. Inner side of part of the left mandibular ramus, showing part of thin inner

alveolar wall (12), of a young Iguanodon.

bo

. Upper view of ditto.

3. Under view of ditto.
4. Outer side of ditto.

In each figure, 1 to 15 indicate the alveolar depressions in the outer wall.
5. Inner side of apex of crown of the successional tooth (6, fig. 1), magnified.

. Inner side of apex of crown of the successional tooth (12, fig. 1), magnified.

[=r

Discovered by the Rev. W. Fox, M.A., in the Wealden, near Brixton, Isle of
Wight.

YOUNG IGUANODON

e
faa As

= < a

2

7h oe
3
*

4

* ‘ : &'* \

¢, - -

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.

LOTT RUT AOS LE, =

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EES?

OF

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Blanford, H. F., F.G.S., 21, Bouverie Street, W.

Boase, H. 8., M.D., F.R.S., G.S., &c., Claverhouse, near Dundee.

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7

Busk, George, Esq., F.R.S., L.S., &c., 15, Harley Street, Cavendish Square, W.
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Cambridge University Library (by the Rev. James Power).

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Corder, Mrs. Ipswich

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8

Darlington Naturalists’ Society (by W. Parker, Esq.)

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2

Eassie, Wm., Esq., High Orchard House, Gloucester.

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9

Farnham, Lord, Carlton Club, 94, Pall Mall, S.W.

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)

10

Hanson, Samuel, Esq., Botolph Lane, E.C.; and 43, Upper Harley Street, W.

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I

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13

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Queen’s College, Cork, (by Messrs. Hodges and Smith).

14

Raban, Major, 7, Old Burlington Street.
Radcliffe Library, Oxford.

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Ramsay, William, Professor of Humanity, University of Glasgow.
Ransome, Robert Charles, Esq., iis

Raulin, Professor, Bordeaux.

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Sits

15

Shipp, W., Esq., Blandford, Dorset.

Sidney Sussex College Library, Cambridge (by the Rev. Robert Phelps, D.D., Master).
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16

Trautschold, Dr., Moscow.

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laa

Wood, Rev. Henry, F.G.S., Holwell Rectory, Sherborne, Dorset.

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Yorkshire Philosophical Society, York.
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Zeuschner, Professor, Cracow.

Os

LIST OF WORKS

ALREADY PUBLISHED BY

THE PALZONTOGRAPHICAL SOCIETY;

Showing the Orpur of publication; the Yuars during which the Society has been in
operation ; and the Contents of each yearly volume.

1847 The Univalves of the Crag, by Mr. S. V. Wood, 21 plates.
The Eocene Mollusca, Part I, by Mr. F. E. Edwards, 9 plates.
1848 { The Chelonia of the London Clay, &c., by Profs. Owen and Bell, 38 plates.
The Entomostraca of the Cretaceous Formations, by Mr. T. R. Jones, 7 plates.
1849 The Crocodilia aud Ophidia of the London Clay, &c., by Prof. Owen, 18 plates.
**") The Permian Fossils, by Prof. Wm. King, 29 plates.
The Fossil Corals, Part I, by Messrs. Milne-Edwards and Jules Haime, 11 plates.
The Bivalves of the Crag, Part I, by Mr. S. V. Wood, 12 plates.
1850 f The Mollusca of the Great Oolite, by Messrs. Morris and Lycett, 15 plates.
(The Fossil Brachiopoda, Part III, No. 1, Oolitic and Liasic, by Mr. Davidson, 13 plates.
( The Reptilia of the Cretaceous Formation, by Prof. Owen, 39 plates.
18514 The Fossil Corals, Part II, by Messrs. Milne-Edwards and Jules Haime, 19 plates.
The Fossil Lepadide, by Mr. Chas. Darwin, 5 plates.
( The Fossil Corals, Part III, by Messrs. Milne-Edwards and Jules Haime, 16 plates,
The Fossil Brachiopoda, Part I, Tertiary, by Mr. Davidson, 2 plates.
1859 The Fossil Brachiopoda, Part II, No, 1, Cretaceous, by Mr. Davidson, 5 plates.
The Fossil Brachiopoda, Part III, No. 2, Oolitic and Liasic, by Mr. Davidson, 5 plates.
The Eocene Mollusca, Part II, by Mr. F. E. Edwards, 6 plates.
The Radiaria of the Crag, London Clay, &c., by Prof. E. Forbes, 4 plates.
(The Fossil Corals, Part IV, by Messrs. Milne-Edwards and Jules Haime, 10 plates.
The Fossil Brachiopoda, Introduction to Vol. I, by Mr. Davidson, 9 plates.
1853 The Shells of the Chalk, Part I, by Mr. D. Sharpe, 10 plates.
The Mollusca of the Great Oolite, Part Il, by Messrs. Morris and Lycett, 8 plates.
| The Bivalves of the Crag, No. 1, by Mr. S. V. Wood, 8 plates.
(The Reptilia of the Wealden Formation, Part I, by Prof. Owen, 9 plates.
The Fossil Brachiopoda, Part II, No. 2, Cretaceous, by Mr. Davidson, 8 plates.
The Reptilia of the Wealden Formation, Part II, by Prof. Owen, 20 plates.
The Mollusca of the Great Oolite, Part III, by Messrs. Morris and Lycett, 7 plates.
18544 The Fossil Corals, Part V, by Messrs. Milne-Edwards and Jules Haime, 16 plates.
The Fossil Balanide and Verrucide, by Mr. Charles Darwin, 2 plates.
The Shells of the Chalk, Part II, by Mr. D. Sharpe, 6 plates.
{| The Eocene Mollusca, Part III, No. 1, by Mr. F. E. Edwards, 8 plates.
(The Fossil Echinodermata, Part I, by Dr. Wright, 10 plates.
The Eocene Mollusca, Part III, No. 2, by Mr. F. E. Edwards, 4 plates.
ae The Shells of the Chalk, Part III, by Mr. D. Sharpe, 11 plates.
The Bivalves of the Crag, No. 2, by Mr. S. V. Wood, 11 plates.
The Tertiary Entomostraca, by Mr. T. R. Jones, 6 plates.
The Reptilia of the Wealden Formation, Part III, by Prof. Owen, 12 plates.
The Fossil Echinodermata, Part II, by Dr. Wright, 12 plates.
The Crustacea of the London Clay, by Prof. Bell, 11 plates.
18564 The Fossil Brachiopoda, Part IV, Permian, by Mr. Davidson, 4 plates,
The Fossil Brachiopoda, Part V, No. 1, Carboniferous, by Mr. Davidson, 8 plates.
The Reptilia of the Wealden Formation, Part IV, by Prof. Owen, 11 plates.
The Fossil Echinodermata, Part III, by Dr. Wright, 14 plates.
1857 The Fossil Brachiopoda, Part V, No. 2, Carboniferous, by Mr Davidson, 8 plates.
The Reptilia of the Wealden Formation, Part V, by Prof. Owen, 12 plates.
The Polyzoa of the Crag, by Prof. Busk, 22 plates.
The Fossil Echinodermata, Part [V, by Dr. Wright, 7 plates.
1858 The Eocene Mollusca, Part III, No. 3, by Mr. F. E. Edwards, 6 plates.
The Reptilia of the Cretaceous and Purbeck Formations, by Prof. Owei, 8 plates.
The Fossil Brachiopoda, Part V, No, 3, Carboniferous, by Mr. Davidson, 10 plates.
fi The Fossil Brachiopoda, Part V, No. 4, Carboniferous, by Mr. Davidson, 20 plates.
18594 The Reptilia of the Lias, No. 1, by Prof. Owen, 7 plates.
(The Eocene Mollusca, Part IV, No. 1, Bivalves, by Mr. 8. V. Wood, 18 plates.
The Fossil Brachiopoda, Part V, No. 5, Carboniferous, by Mr. Davidson, 8 plates.
1860 The Reptilia of the Lias, No. 2, by Prof. Owen, 12 plates.
The Fossil Estherie, by Prof. Rupert Jones, 5 plates.
The Crustacea of the Gault and Greensand, by Prof. Bell, 11 plates.
1861 { The Fossil Echinodermata, Vol. I, Part I (Oolitic Asteroidea), by Dr. Wright, 13 plates,
Supplement to the Great Oolite Mollusca, by Dr. Lycett. 12 plates.
(The Fossil Cretaceous Echinodermata, Vol. I, Part I, by Dr. Wright, 11 plates.
J The Trilobites of the Silurian, Devonian, &c., Formations, Part I, by Mr. J. W. Salter, 6 plates.
18624 The Fossil Brachiopoda, Part VI, No. 1, Devonian, by Mr. Davidson, 9 plates.
| The Eocene Mollusca, Part IV, No. 2, Bivalves, by Mr. 8. V. Wood, 7 plates.
(The Reptilia of the Cretaceous and Wealden Formations (Supplements) by Prof. Owen, 10 plates.

19

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