a hed C437 2 re hinederms THE VOYAGE OF H.M.S. CHALLENGER. AOOWOGY. REPORT upon the Crivoipea collected during the Voyage of H.MLS. Challenger during the Years 1873-76. By fd epee CARPENTER, D.Sc., Assistant Master at Eton College. , PART I—GENERAL MORPHOLOGY, WITH DESCRIPTIONS OF THE STALKED CRINOIDS. PREFACE. Tur circumstances under which I have come to be charged with the duty of reporting upon the entire collection of Crinoidea made during the Challenger Expedition are as follows.—The researches of my father, Dr. Carpenter, C.B., F.R.S., early led me to take a special interest in Comatula and its allies. Some of his statements respecting the anatomy of the arms having been called in question, I was led to reinvestigate the matter towards the end of the year 1875, by methods which were almost unknown during the progress of his researches nearly fifteen years before ; and I had the pleasure of verifying all those points in his descriptions of the arms of the European Comatule which other observers had disputed. I was then working in the zoological laboratory of Prof. C. Semper at Wiirzburg, who most kindly placed at my disposal the arms of some tropical Comatulze which he. had obtained in the Philippines. It soon appeared that the minute structure of Crinoids offered a promising field for investigation, and Prof. Semper therefore generously put into my hands several specimens of aremarkable tropical Actinometra as material for a monograph of the type. This work occupied me during the whole of the year 1876 (ZOOL. CHALL, EXP.—PART xxxiI.—1884.) a fea rsoniian ise Ss YS C ui; 4/9, ( 0600 NET Sonal Mise yy7 il THE VOYAGE OF H.M.S. CHALLENGER. and the earlier months of the following year, the greater part of which time was spent at Wiirzburg, where I had the constant advantage of Prof. Semper’s criticism and advice. I also received much valuable help from my father, who freely placed at my disposal all the material which he had accumulated some years before for his mvestigation of the structure of Antedon, Pentacrinus, and Rhizocrinus. A portion of his observations were communicated to the Royal Society in his now classical memoir on the skeleton of Antedon rosacea, and in a later paper on the anatomy of the disk and arms. but he has still a large amount of unpublished material; and of this I have always been permitted to avail myself as fully -} I wished. How important this help has been to me will be vppareit to every subs quent worker at Crinoid morphology, my own researches having followed very closely on \the lines which he had laid down. The results of my study of Aetinomeira aud various other Crinoids were communicated to the Linnean Society in the sumumer of 1877, and shortly afterwards Sir Wyville Thomson offered to entrust me with the preparation of the Report upon the Comatule dredged by the Challenger. The collection was sent to me in January 1878; and for the next four years the time which I could spare from my professional duties was devoted pretty continuously to the examina- tion and description of some hundred and fifty new species. Eighteen plates had been drawn and nearly all the specific diagnoses written out, when on Sir Wyville’s untimely death in March 1882 I was requested by Mr. John Murray to include the Stalked Crinoids in my Report. During the cruise of H.M.S. Challenger, and also for some years before it, Sir Wyville had devoted much attention to the Stalked Crinoids, and he proposed himself to investigate the collection of this group of animals which was made during the Expedi- tion. He also arranged with Prof. Alexander Agassiz that he should embody the descriptions of the Stalked Crinoids dredged in the Caribbean Sea by the U.S. Coast Survey steamer “ Blake” in his Report on the Challenger collection, so that it might assume the form of a monograph of all the species known to science. He was able to do but little with the “‘ Blake” collection, however; and with the concurrence of Prof. Agassiz it was sent to me by Mr. Murray along with the Challenger collection, proofs of plates, drawings, preparations, and some notes, in the spring of 1882. Sir Wyville had not made much progress with the preparation of his Report. Twenty- eight plates illustrating the structure of Holopus and of the more remarkable types dredged by the Challenger had been drawn and lithographed at Edinburgh under his superintendence by Messrs. George West and W. 8. Black, but he was never able to draw up any specific diagnoses; and he left no manuscript behind him of any kind, except one or two generic and specific names which he had written upon the proofs of some of these plates. Descriptions of Hyocrinus, Bathycrinus, and of Pentacrinus maclearanus had, however, already been published in his popular work on the Voyage of the Challenger—The Atlantic. REPORT ON THE CRINOIDEA. ill Upon examining the two collections of the “Blake” and the Challenger, I found that they contained some half dozen species of which no figures had been drawn at all; so that several additional plates would be necessary in order to illustrate them adequately ; while diagnoses were wanted of nearly thirty specific types, most of them being undescribed, and some representing new genera. The preliminary study of these various forms in their zoological aspect alone occupied a good deal of time; but having a strong conviction that they could only be properly understood by the help of a detailed knowledge of their fossil representatives, I was led to take up the study of the fossil Crinoids, more especially those of th Sevondary end Tertiary periods. This naturally brought up the question of the relation between os Neocrinoids and the Paleocrinoids, which had already been occupying my ‘ioughts for some time past. Besides these paleeontological questions, many others presented cticimselves oi a morphological nature; and I have endeavoured to obtain such a knowledge of the morphology of recent Crinoids as would be of substantial aid in the interpretation of the many puzzling forms among their fossil representatives, and also bring out their relation to the other Echinodermata. Many others have been at work upon the same lines, with varying opportunities and different degrees of success. Very much, however, still remains to be done, more especially with regard to the finer details of microscopic anatomy, which can only be thoroughly investigated in individuals specially prepared for the purpose when quite fresh. In this way alone is it possible to obtain series of sections of the requisite thinness and perfection of histological detail ; and I would therefore ask those who may be disposed to criticise my figures to remember that the preparations were mostly made before the introduction of the Jung or Caldwell microtomes, from material which had been in spirit for periods varying from two to fifteen years. Several morphological and one or two systematic works upon the Crinoids have appeared during the passage of this Report through the press ; and I have therefore added an Appendix which contains a series of notes discussing the various questions to which those works relate. Reference is given to these notes in the text, so that this first part of the Crinoid Report may be regarded as presenting an epitome of our knowledge of Crinoid structure up to the end of the present year. The second part of the Report, containing descriptions of the Comatulz collected by the Challenger and “ Porcupine,” will be published as soon as ever the necessary plates can be drawn, and the manuscript revised, parts of the latter being now more than five years old. Of the sixty-nine plates accompanying Part I., twenty-eight were drawn at Edin- burgh under the direction of Sir Wyville Thomson. Five others illustrating the structure of Pentacrinus wyville-thomsoni were prepared by Mr. George West to accompany a memoir upon this type, commenced some years ago by my father, who has lv THE VOYAGE OF H.M.S. CHALLENGER. kindly permitted me to make use of them here. They are distinguished by the initials “W.B.C.”; while thirty-one of the remaining thirty-six which are marked “ P. H. C.,” have been drawn under my own superintendence by Messrs. C. Berjeau, F.L.S., and P. Highley. I am very greatly indebted to both these gentlemen for the care and skill with which they have performed a difficult and laborious task, one, moreover, involving a considerable acquaintance with minute structural details. I am under similar obliga- tions to Mr. George West, who lithographed three anatomical plates, and also gave me valuable information respecting the specimens from which he had drawn several plates foy Sir \yyville Thomson. I have likewise to thank Mr. Black for similar information concerning those plates which had been drawn by himself; and also Mr. W. E, Hoyle, M.A., of the Challeager Office, for kindly working out the magnification of some of the figures upon Mr. Black’s plates. i have fucther gratefully to acknowledge much valuable bibliographical assistance from . my friends Prof. F. J. Bell, F.Z.8., and Mr. W. P. Sladen, F.L.S.; while my thanks are also due to Prof. H. N. Moseley, Dr. P. P. C. Hoek, Mr. H. B. and Dr. G. 8. Brady, and to Mr. Edgar Smith, F.Z.8., for kindly identifying various organisms which I had found attached to different parts of the Crinoids. Prof. Carl Zittel of Munich and Prof. G. Meneghiniof Pisa have been good enough to send me several fossil specimens of Rhizocrinus for examination, and I take this opportunity of thanking them. But I find it difficult to express my indebtedness to Mr. Charles Wachsmuth of Burlington, Iowa, U.S., who is so well known as the leading authority upon the Palzocrinoidea. Not only has he frequently sent me for examination very rare and valuable specimens illustrating the morphology of the Palzocrinoids and Blastoids, but he has repeatedly answered my inquiries in the fullest and most complete manner possible. The relations of the Neocrinoids and the Paleocrinoids have been the subject of a prolonged discussion between us, extending over more than two years; and it is a matter of sincere regret to me that we have been obliged to agree to differ. Time will show how far our respective views will need modification. We have approached the subject from different sides ; but upon one point we are in complete accordance, viz., the desire to find out the truth, whether or not it agree with our own ideas upon the subject. Mr. Wachsmuth will shortly publish an explanation of his own position, to which I would refer those who are interested in the matter. In conclusion, I must express my sincere thanks to Mr. John Murray and to Prof. Alexander Agassiz for having entrusted me with the working out of the Crinoid collections in their charge, and for their readiness to afford me every possible assistance in doing so; while I would pay a heavy debt of gratitude to the memory of the late Sir Wyville Thomson. It was my privilege to accompany him and my father in the short but eventful cruise of H.M.S. “ Lightning” in the year 1868 and in the “ Porcupine” expedition of 1869; and to his kindness and encouragement both then and sub- REPORT ON THE CRINOIDEA. Vv sequently is due much of such success in zoological work as I may subsequently have attained. To my father, as will be readily understood, I owe far more than can well be put into words ; and I will only express the hope that the following pages may be regarded as a not unworthy sequel to his many contributions to Invertebrate Zoology. Eron Cottece, December 1884. TABLE OF CONTENTS. MORPHOLOGY. I.—Tue SKELETON GENERALLY, WITH THE MopEs or UNIon OF ITs COMPONENT JOINTS, Syzygies, Articulations, I[.-—Tuer Stem anp 17s APPENDAGES, . A. Pentacrinide, . ; P Termination of the Stem below, B. Bourgueticrinide, Morphology of the Stem, C. Hyocrinide, I1J.—Tue Catyx, A. The Basals, B. The Radials, C. The Interradials, Anal Series, IV.—Tue Rays, A : ; é A. The Ray-Divisions and Arms, . B. The Pinnules, . : 2 Pinnules of Paleocrinoids, . V.—Tue ViscrraL Mass, A. The Oral Plates, B. The Perisomatic Skeleton, C. The Visceral Skeleton, V1I.—Tue Minute Anatomy oF THE Disk AnD ARMS, The Geography of the Disk, The Digestive Tube, The Water-Vascular System, . The Blood-Vascular System, Labial Plexus, Plexiform Gland, Chambered Organ, . . The Genital Glands, . The Nervous System, Ambulacral Nerve, . Axial Cords, Parambulacral Network, Circular Commissure, : G. The Sacculi, and the Colouring Matters, yawP i PAGE Vill THE VOYAGE OF H.M.S. CHALLENGER. VII.—On tHe Hasits oF RECENT CRINOIDS, AND THEIR PARASITES, Modes of Attachment, Myzostoma, VIII.—Tue GrocraPHIcAL AND BATHYMETRICAL DISTRIBUTION OF THE CRINOIDS, A. Geographical Range, B. Bathymetrical Range, C. The Association of the Genera at Pavioulat Stations: IX.—On THE RELATION BETWEEN THE RECENT AND THE Fossii Neocrinoips, X.—On THE RELATIONS OF THE NEOCRINOIDS TO THE PALMOCRINOIDS, The Miillerian Classification ; Articulata and Tessellata, General Characters of the Neocrinoids, Structure of the Calyx, Characters of the Arms, The Disk and Oral Plates, The Vault of the Paleocrinoids, Vault of Haplocrinus, Allagecrinus, and Conturenas, Vault of Cyathocrinus, Subtegminal Ambulacra, Vault of Actinocrinide, Homologies of the Calyx and Dorie Plates Radial Dome Plates, Vault of Platycrinide, Vault of Ichthyocrinide, ; . Vault of Glyptocrinus, Reteoerinus, and fees XT.—CLAssIFICATION, : Definition of the Pelmatozoa, Definition of the Crinoidea, . Other Systems of Classification, Characters of the Pelmatozoa, Definition of the Neocrinoidea, XII.—Descrretion or THE SPECIMENS, Family Holopide and Genus Holopus, A. General Account of the Type, Holopus rangi, VOrbigny, The Calyx, ‘ The Axillary Radials, . The Arms, The Disk and ienbulaera! Anatomy of the Arms, . : B. On the Systematic Position of Holopus, Cyathidium, Cotylecrinus, Eudesicrinus, Gymnocrinus and Micropchnas Edriocrinus, REPORT ON THE CRINOIDEA. Family Hyocrinide, and Definition of Hyocrinus, A. General Account of the Type, Hyoerinus hethelidannes Wyville Thomson, B. On the Systematic Position of Hyocrinus, . : Family Bourgueticrinide, Definition of genus Bathycrinus, . Structure of the Calyx, Distribution of the Axial Cords, : Trifascial Articulations of the Outer Radials ad Arm- J oints, . The Disk, Axial Cords of the emis 3 Comparison of Bathycrinus and Rhizocrinus, Bathycrinus campbellianus, n. sp., aldrichianus, Wyville Thomson, gracilis, Wyville Thomson, Definition of Genus Rhizocrinus, Characters of Conocrinus, ‘ Composition of the Calyx in Rhizocrinus, Views of Pourtalés, Sars, and Ludwig, Distribution of the Axial Cords, Syzygies in the Arms, Affinities of Rhizocrinus, ; Rhizocrinus lofotensis, M. Sars, rauwsoni, Pourtales, : Variations in the Shape of the Calyx, . The genus Democrinus, Perrier, Definition of the family Pentacrinide, Synopsis of the Genera, Genus Pentacrinus, A. Characters of the Genus, Characters of Hxtracrinus, Cenocrinus and Neocrinus, Cainocrinus, Variations in the Size of the Basle in Pantie Arms of Pentucrinis, Characters of the Stem, B. On the Characters of Young Pentacrinide, C. The Calyx and its Contents, D. The Geological History of Pentacrinus, Synopsis of the recent Species, Pentacrinus asterius, Linn. sp. miller’, Oersted, maclearanus, Wyville Thomson, wyville-thomsoni, Jeffreys, . : Termination of the Stem below, and the Mode of Eh ecnmont of ae Den tatriniilie Pentacrinus alternicirrus, 1. sp., NATesianus, . SP. blaket, P. H. Carpenter, decorus, Wyville Thomson, Variability of its Characters, Pentacrinus mollis, n. sp., (400L, CHALL, EXP,—PART xxx11.—1884.) b bo bo bo bb b&b bo eo US ES Re bo b bo jo ww onl to ~I iS) bo bw by WS bw bd bs bv seme uo MmMOoOoDmDnDonnr at Lo) on EP LOR © FE OO 2 bo b bo x THE VOYAGE OF H.M.S. CHALLENGER. PAGE Definition of genus Metacrinus, . 5 : : . : . 339 Synopsis of the Species, : 4 . ; : : . 3844 Metacrinus angulatus, 0. sp., - : . : . é . 345 cingulatus, D. Sp., - P 5 ‘ 5 , ee OAT Murray, D.S8)p., — - : ; : : : . 9349 nobilis, N. sp. . ; ? . 3 ; . 351 varians, 2. Sp., —. : : : : : - 3853 moseleyt, D. sp... : . ‘ ; 3 a8 (ODD: wyvillii, Dn. sp., —- c 5 5 ; : . 308 costatus, 1. sp., : : 3 : ; : . 360 nodosus, D. 8p. 5 ; ; : A ood: interruptus, 0. Sp., - : : . : ; oe cli tuberosus, D. Spy - : : 3 . , 369 family Comatulide, and Definition of genus HM eee : : : a) eo) Thaumatocrinus renovatus, P. H. Carpenter, . 3 . . - 32 {1,—Bavurmetrica® DisTRIBUTION AND Station Lists, P 374 tation List of the Stalked Crinoids which have been eesti by the various s British J ns for Deep-Sea Exploration between the Years 1868 and 1880, .. ous: Station Tae t of the Stalked Crinoids which have been obtained by the various American Expeditions for Deep-Sea Exploration (mostly under the direction of Mr. Alexander Agassiz) between the Years 1867 and 1880, . ; 379 A List of the known Living Species of Stalked Crinoids, Shenae their Bathpmcical aa Geographical Distribution, . : i 5 , : 5 . 3885 Analysis of this List, é : ; ; . j ; : . 388 Bathymetrical Tables, ; ; : : : ; : : . 388 Summary, : : : : ‘ : : . 390 Crivoids of the itty ssal Tees : : : . 5 : : Beeotuil APPENDIX. PAGE Nore A.—On the Homologies of the Crinoidal Calyx in the other Echinoderms, ; : oe Apical System of Urchins and Starfishes, : 5 5 Pls. XXXV— XXXVIT.; Pl. XXXIX. fig. 1; Pl. XLII). In some species (of Metacrinus especially) this condition is retained throughout the whole length of the stem (Pl. XXXVIIL; BIOECXEX. fies. 3-11; Pl. XL; Pl) XLIX, figs. 1-3); but in others the joints gradually become more rounded, or at any rate pentagonal, as new ones are formed successively above them (Pl. XI.; Pl XIII. fig. 11; Pl. XIX. fase 154,55) Pl. XXII. fies: Tone 23-26; Pl. XXVIII. fig. 2; Pl. XXX. figs. 25-30; Pl. XXXVI.; Pl. XLI. figs. 3, 7; Pl. XLVIL figs. 4, 8). A continual production of new joints goes on at the top of 1 Encriniden, pp. 196, 230, Tab. 98, figs. 2, 3, 107. * Monographie des Crinoides fossiles de la Suisse, Mém. Soc. Pal, Swisse, 1877-79, pp. 122, 144. 16 THE VOYAGE OF H.M.S. CHALLENGER. the stem immediately beneath the calyx, what appears to be the top stem-joint in a side view having one or two more smaller joints resting in its upper surface but not reaching the exterior as shown in Pl. XXXIV. fig. 9. The top stem-joint—for the time being—of a specimen of Pentacrinus wyville- thomsoni is shown in Pl. XXII. fig. 2. Resting on its upper surface is a smaller stellate plate without any markings whatever, which in its turn would appear as the top stem- joint until it was replaced by the development of another above it. As these joints are relatively carried downwards from the calyx in succession by the appearance of younger ones above them, they also become separated from one another by the intercalation of new joints between them. Various stages of this process are shown in Pl. XXII. figs. 9-12, while fig. 4 shows an isolated young joint, and fig. 5 the depression in the next joint, which lodged it. Similar intercalated joints are shown in Pls. XXIL. fig. 3, and Pl. XXIII. figs. 1,2. The result of this process is that the growing part of the stem appears to consist of thick and thin joints alternating with one another (Pl. XIII. fig. 1; PIX. Ply MV. figs. 1, 25, Pl.) XV fig. 1, 25) Pl KEK hie, 2G feels SAY. XV XK KXKIV.-XXKVIL;, Pl. XXXIX. fig, 1; (PL SEM hs. 27 PX Eye fig. 2). The former are the older, the latter bemg subsequent additions. These intercalated joimts are always internodal, and the process goes on until the number of joints between any two nodes reaches a certain average, which is constant for each individual species. There are many indications that the increase in length of the stem of the fossil Pentacrinidze was due to the same process. Quenstedt’ gives an excellent figure of a young concealed joint superposed upon an older and larger one, very much as shown in Pl. XXII. figs. 9-12; and others of his figures upon the same plate illustrate the different stages of growth on the stem of Hatracrinus subangularis, as many as three or four concealed joints being sometimes found intercalated between two of the larger ones. In this species, too, with a stem which may reach 50 or 70 feet in length, the production of nodal jomts at the top of the stem must have been very rapid. According to Quenstedt? forty or more succeed one another without any internodal joints being visible externally, though the presence of concealed intercalated jomts is revealed by the examination of longitudinal sections of the stem. The final result of their growth was to enormously increase the total number of internodal joints. Stem-fragments have been found by Quenstedt consisting of as many as eighty joints, all internodal, and it is impossible to say how many more there may have been; while he states that he finds traces of small intercalated joints in almost every part of the stem. In most cases the new joints which have been intercalated between two older ones eventually reach the same size as their predecessors, so that it is difficult to tell the older from the younger joints in any mature stem. But in some species there appears to 1 Encriniden, p. 298, Tab. 101, figs. 24a, 240. 2 Thid., p. 297, Tab. 101, figs. 16-19, REPORT ON THE CRINOIDEA. 7/ be a permanent inequality, large and small joints alternating all down the stem. This is the case, for example, in the fossil Pentacrinus jaccardi and Pentacrinus nicoleti figured by de Loriol,t and also to some extent in the recent Metacrinus moseleyi (Pls. XLV., DaGY I): There is very little difference between the upper and the under faces of the young nodal joints, or between either of them and the ordinary internodal joint (Pl. XXII. figs. 1, 6-8, 15; Pl. XXXa. figs. 2, 3; Pl. XXXVII. figs. 14-16; Pl. LI. figs. 2-5). But as the jomts become older and more pentagonal their differences are more apparent (PL XIIL figs. 2, 3, 5,6, 10; Pl. XXII. figs. 16-18; Pl. XXXVI. figs. 11-13, 17, 18); while in the lower part of the stem the simple syzygial nature of the under face of the nodal jot and its loss of the denticulate petaloid markings become very distinct (EE SSVeotie G5) Bl XX figs, 19, 20; Pla XXVI. figs. 13, 14; Pl, XX VIL fies. 2.3; PL XXX. figs. 26, 27; Pl. XXXVII. figs. 21, 22; Pl. XXXIX. figs. 4,5; Pl. XLV. figs. 4,5; Pl. L. figs. 21, 22). In some species of Pentacrinus, e.g., Pentacrinus wyville-thomsoni, the lowest and therefore the oldest stem-joints gradually lose the more or less prominent ridges which appear on the faces of those higher up the stem, and become much more smooth and simple in their character (Pl. XXII. figs. 23-26). A similar change seems to take place in Pentacrinus asteria (Pl. XIII. figs. 10, 11), and also in other species, though I have not been able to trace it so distinctly as in Pentacrinus wyville-thomson. It is manifested externally by the gradual disappearance of the crenulation of the interarticular lines, which is so very prominent in the upper and middle parts of the stem (Pl. XIII. figs. 7, 8; Pl. XV. figs. 1, 2, 4; Pl. XIX. figs. 2-5; REE PELE XXVIL fig, 15) Pl XOX. fig. 3 yp Pls. XXXV.-XRAKVIT; Plo ee fers aelly Sek Or;) Ble NUTT. fig: 1). The amount of crenulation varies considerably in different species, according to the position of the large teeth bordering the outer ends of the petaloid spaces. When these start from near the edge of the joint, as in Metacrinus cingulatus, Metacrinus nobilis, or Metacrinus costatus (Pl. XLI. figs. 1-3, 5-7 ; Pl. XLIX. figs. 3-5), the interarticular line is well crenulated. But there is sometimes a sort of rim outside the ends of the teeth, as in Metacrinus murrayt and Metacrinus varians (Pl. XLI. figs. 15, 17; Pl. XLVIL. figs. 6-9), and the external crenulation is then less marked. This outer rim is only formed comparatively late, the teeth of a young joint starting directly from its edge, as is well shown in Pls. XXII., XXIII., and XX XVII. The increase in the length of the internodes only takes place gradually, and pari passu with the continual formation of new joints just below the calyx. Hence, in the upper part of the stem, there is a variable number of premature internodes, those nearest the summit being the shortest, and consisting of the smallest number of joints. The 1 Swiss Crinoids, pp. 130, 140, pl. xv. figs. 13, 36, (ZOOL. CHALL, EXP.—PART XXx11.—1884.) 3 18 THE VOYAGE OF H.M.S. CHALLENGER. upper part of the stem is also distinguished from the more fully grown portion below it by the presence of the “ interarticular pores.” These are small pore-like openings between the successive joints which are situated in the re-entering angles between the interradial ridges, and are therefore radial in position (Pl. XI.; Pl. XIII. fig. 7; Pl. XV. figs. 1, 2; Pl, XIX. figs, 2, 3; Pl. XXV.; Pls. XXVIIL, XXIX., XXXIV=XXXVIIL, XLIV., XLVII.; Pl. XLIX. fig. 2; Pl. L. figs. 1, 3). They are produced by the apposition of two faint grooves radiating outwards from the centres of the contiguous joints, which are largest at their central ends and shallowest towards the periphery (PI. XIII. fig. 9; Pl. XXII. figs. 8, 10, 12; Pl. XX XVII. figs. 10-18, 20, 22). They do not reach the central canal of the stem; and so there is no communication effected by the agency of these pores between the internal vascular axis and the exterior. Similar openings occur in many Comatulz, leading into spaces between the upper surface of the centro-dorsal and the under surfaces of the radials which rest upon it ;* but they effect no communication between the body-cavity and the external medium. Until comparatively lately but little has been known respecting the termination of the lower part of the Pentacrinus stem. Nearly all the specimens obtained had a fractured stem, from which no conclusions could be drawn. From what we know of the development of the Comatule we may fairly assume that the young Pentacrinus commences life attached to some foreign body by means of a terminal plate (the dorso- central) at the base of its stem, and a calcareous expansion subsequently developed around it. Mature individuals have been found attached in this way to telegraph cables. Capt. E. Cole of the telegraph steamer “Investigator” has reported to Prof. Agassiz “that he has frequently brought up the West India telegraph cable on which Pentacrim were attached, and that they are fixed, the basal extremity of the stem spreading slightly, somewhat after the manner of Holopus, so that it requires considerable strength to detach them.”? The condition of the lower part of the stem fragment of Pentacrinus naresianus, represented in Pl, XXXa. fig. 4, is perhaps due to this mode of attachment. At the same time there appears to be ample evidence that a Pentacrinite may lead the same sort of free life that a Comatula does, attaching itself temporarily by its cirri. Sir Wyville Thomson long ago pointed out, in the case of Pentacrinus decorus,’ “ that the animal seems to have had the power of detaching itself” at any of the syzygies of the stem in the same sort of way as the arms are thrown off during life, or break up after death. He described an individual in which the stem terminated below in a worn and rounded nodal joint, and he supposed it ‘‘ to have finally parted from its attachment and to have led a free life.” He stated some years afterwards that this was the case in all the complete specimens which he had seen, “ showing that the animal must have been for long free from any attachment to the ground.”* He then went on to describe the same 1 The Genus Actinometra, loc. cit., pp. 88-90, pl. viii. figs. 5, 7. * Bull. Mus. Comp. Zool., vol. v. No. 14, p. 296. 3 Sea Lilies, p. 7. ‘ The Depths of the Sea, pp. 442-444, oft wot) inal Sha Poe ae a REPORT ON THE CRINOIDEA. 19 condition as it occurs in Pentacrinus wyville-thomsoni. “All the stems of mature examples of this species end inferiorly in a nodal joint surrounded by its whorl of cirri, which curve downwards into a kind of grappling root. The lower surface of the terminal joint is in all smoothed and rounded, evidently by absorption, showing that the animal had for long been free. I have no doubt whatever that this character is constant in the present species, and that the animal lives loosely rooted in the soft mud, and can change its place at pleasure by swimming with its pinnated arms; that it is, in fact, intermediate in this respect between the free genus Antedon and the permanently fixed Crinoids.” Many other species of Pentacrinus and some of Metacrinus exhibit the same condition. It is best seen in Pentacrinus wyville-thomsoni, in which the nodal joint sometimes loses its ordinary characters altogether, becoming much enlarged and rounded below so as to be almost hemispherical in appearance (PI. XXII. fig. 27). In other cases, however, it retains its petaloid form and more or less of the small amount of sculpture which is usually found upon its lower face ; and a small rounded tubercle appears in the centre of the latter closing up the opening of its central canal. This is the usual condition of other species of Pentacrinus (e.g., Pentacrinus asteria, Pl. XI.) and of Metacrinus; and the analogy between it and the condition of a young Comatula just detached from its stem is very striking, as was pointed out by Sir Wyville Thomson.’ In both cases the severance takes place between a nodal joint and the top joint of the internode below it. The relations of the two longest stems that I have met with in this condition are shown as follows :— Pentacrinus decorus, stem 48 cm. long, rounded off at the thirtieth node. Metacrinus angulatus, stem 38°5 em. long, rounded off at the thirty-fifth node. With one exception (Pentacrinus maclearanus, Pl. XVI.) the three shortest of these semi-free stems that I have examined all belong to Pentacrinus alternicirrus. A, 47 mm. long, ends at the eleventh node; B, 49 mm., ends at the eleventh node; and ©, 55 mm., ends at the twelfth node. On the other hand, the smallest number of nodes in a semi-free stem oceurs in Pentacrinus wyville-thomsoni; one individual having a stem 90 mm. long, which 1 The unusual enlargement of the lowest nodal joint in this individual suggests the idea that the structures which have been described by Hall under the name of Ancyrocrinus(Fifteenth Annual Report, New York State Cabinet of Natural History, 1862, pp. 89, 90) may be the detached stems of a Paleocrinoid in the semi-free condition. According to Hall they “have the form of a bulb or thickened column, with lateral ascending processes and a central ascending column of greater or less length ;” and he suggests that they “indicate the existence of a free floating Crinoid with the thickened bulb below serving as a balance for the column and body above. The articulating scar on the lower extremity of the smaller ones indicates that the animal was fixed in its young state.” The four lateral spine-like processes may very well have been cirri, the jointed structure of which has become obliterated by a calcareous overgrowth, just as in the lower part of the tetramerous stem. ? Sea Lilies, p 10. 20 THE VOYAGE OF H.M.S. CHALLENGER. ends at the sixth node. This is due to the great length of the internodes in this species CPL VII fie. 3; Pl. XIX. fig. 1). Pentacrinus maclearanus presents exactly the opposite type of structure. There are only twelve nodes in the stem of the solitary individual obtained (Pl. XVI). But these all occur in a stem barely 40 mm. long, as there are never more than two, and generally only one internodal joint ; while the cirri cluster thickly round the stem, so that it has an appearance more like that of Hatracrinus briareus than is commonly met with in the Pentacrinide. It is noteworthy that in the last-named species the stem does not seem to have reached any great length, and that it sometimes tapered downwards.’ This peculiarity was also noticed by MM. Eudes-Deslongchamps in some stems belonging to a large colony of Pentacrinites which they discovered in the Great Oolite of Soliers, near Caen ;? while it is very characteristic of Millericrinus pratt: from the same horizon in Gloucestershire ;* and also of the Carboniferous Woodocrinus, certain Blastoids, and of the Silurian Glyptocystites, Plewrocystites, and other forms. The most remarkable instance of this in a fossil Crinoid, however, is that of the Lower Silurian Glyptocrinus schafferi of S. A. Miller,* for which he has recently established the new genus Pycnocrinus. In one specimen found by Miller the lower part of the stem was “wound around a Crinoid column of a distinct species, almost as neat as a thread can be wound upon a spool. The column gradually tapers as it coils, until it becomes so small as to be scarcely visible to the naked eye, the larger plates of the column which give it that banded appearance, or make it resemble a string of small spools, gradually diminish, and before the column terminates it becomes as smooth as a silken thread.” Two other species from the same locality at Cincinnati, Lichenocrinus dubius and Dendrocrinus navigiolum, were also found by Miller to have tapering stems. In the case of the former he infers that ‘‘the column was free and used to direct and guide the course of the animal through the water, and perform such other functions as were performed by the columns of other floating Crinoids, except that it was never used for purposes of attachment.” One must not, however, conclude at once, from the tapering condition of the stem in a fossil Crinoid, that the animal was free in its habits. In a young Lucalyptocrinus crassus, for example, which is figured by Hall,’ the stem tapers downwards very considerably, but is attached below by a spreading root. I have found a tapering stem in certain individuals belonging to six species of recent Pentacrinide, but it appears to be the exception rather than the rule, and is therefore entirely devoid of any systematic value. 1 Encriniden, p. 271. 2 Etudes sur les ¢tages Jurassiques inférieurs de la Normandie, Paris, 1864, p. 232. 3 On some new or little known Jurassic Crinoids, Quart. Journ. Geol. Soc., vol. xxxvill. pp. 31-33, pl. 1. figs. 6-8, 10-14. 4 Description of four new Species and a new variety of Silurian Fossils, and remarks upon others, Journ. Cincinn. Soc. Nat. Hist., vol. iii., 1880, pl. vii. fig. 3, p. 2 (of separate copy). 5 Twenty-eighth Annual Report of the New York State Museum of Natural History, Albany, 1879, pl. xvii fig. 5. ef) a Sd REPORT ON THE CRINOIDEA. Pail In one example of Pentacrinus alternicirrus, which has a stem only 55 mm. in length, and rounded off at the twelfth node, the width diminishes gradually from above downwards, though not to any very great extent. The same is the case in another specimen with a stem 47 mm. long and rounded off at the eleventh node. In other examples of the same type, however, the width of the stem remains uniform or even increases slightly from above downwards. In a large specimen of Pentacrinus naresianus the width of the stem, which is 5 mm. at the eighth node, is reduced to 3°5 mm. by the thirtieth node, which is rounded off below. In the young Pentacrinus wyville-thomsoni represented in Pl. XVIII. fig. 3, the stem is 65 mm. long; but it is not half as wide at the lowest (sixth) node as it is beneath the calyx. It was described by Sir Wyville Thomson’ as follows:—‘The stem is broken off in the middle of the eighth internode from the head. The lowest complete internode consists of fourteen joints, the next of eighteen, the next of twenty, and the next of twenty-six joints. There are eight joints in the cirri of the lowest whorl, ten in those of the second, twelve in those of the third, and fourteen in those of the fourth. This is the reverse of the condition in adult specimens, in all of which the numbers of joints in the internodes, and of joints in the cirri, decrease regularly from below upwards. The broken internode in the young example and the three internodes above it are all atrophied and undeveloped; and suddenly at the third node from the head the stem increases in thickness and looks as if it were fully nourished. There can be no doubt that in early life the Crinoid is attached, and that it becomes disengaged by the withering of the lower part of the stem.” ” The diminution in the size of the stem is rather more gradual than is implied in the above description, for it commences at the head and extends regularly down to the third node, where there is a more sudden change, as there is again at the fourth, below which the diameter decreases but slowly. But it is in a very young individual of Pentacrinus decorus (Pl. XXXV.), in fact the youngest Pentacrinite that I have seen, that this downward tapering of the stem and gradual diminution in the size of the cirri are most marked. The stem isa trifle over 60 mm. in length, and has ten distinct cirrus-whorls apart from the very small 1 On the Crinoids of the “ Poreupine” Deep-Sea Dredging Expedition, Proc. Roy. Soc, Edin., vol. vii. p. 768. Also in the Depths of the Sea, p. 445. 2 The above description requires a little correction. The stem in its present condition, as represented in PI. XVIII. fig. 3, is broken at the top of the seventh internode, which is certainly the one referred to by Sir Wyville as the eighth. But its length is at least 5 mm. greater than as stated by him; and the number of joints in the two lowest internodes should be given as fifteen and seventeen, not fourteen and eighteen. They are drawn correctly in the figure, but the joints at the top of the third internode are not properly represented, as is also the case with some of the cirri. The figures of this and of the other plates drawn for Sir Wyville Thomson had been on stone for so long when the stalked Crinoids came into my hands after his death, that I thought it better to let any errors remain unaltered rather than to risk spoiling the plate by correcting them. The description given of the cirri is also only roughly accurate. Neither on the fourth whorl from the bottom nor anywhere else on the stem are there any cirri with fourteen joints, even where the terminal claw is included; though the regular decrease in the size of the cirri from above downwards is very striking, as pointed out by Sir Wyville. 22, THE VOYAGE OF H.M.S. CHALLENGER. ones just beneath the calyx. Throughout its whole length it tapers downwards from the calyx, rapidly at first, then more slowly and afterwards somewhat rapidly again, till the joints are but little larger than those of the most developed cirri on its middle part. The number of internodal joints also diminishes in this lower part of the stem ; for while it reaches eleven or twelve in the middle of the stem, the numbers in the four lowest internodes are respectively nine, seven, five, five ; and the remains of the cirri borne at the intervening nodes show a corresponding diminution in size. The inferior termi- nation of the stem is not known, as it is broken at the syzygy beneath the lowest whorl of cirri. The free mode of life appears to be attained in these individuals, not by actual fracture of the stem at a node so as to shorten it more or less, but by the lower and therefore older part remaining undeveloped, while new joints appear in succession above it, each growing to a larger size than those previously formed. The stem thus becomes slender and tapering, and but ill adapted for attaching itself below; but its length is not diminished so much as if it were broken at a node. The downward tapering of the stem in some of the fossil Pelmatozoa has been already noticed; and it is evidently a character of more general occurrence than was suspected by Sir Wyville Thomson. Quenstedt’ contrasts the comparatively short tapering stems of Kxtracrinus briareus with the gigantic ones of Hatracrinus subangularis, which may reach the length of 50 or even of 70 feet; and he suggests that the former type and its allies “kénnten gleichsam als ee Comatula betrachtet werden, deren Knopf zu grésserer Liinge in einer Zeit heranwuchs, wo es noch keine eigentlichen Comateln gab.” De Loriol? in like manner regards it as probable—“ quwils avaient, & l'état adulte, une tige court, libre, et qu’d l’aide de leurs cirrhes tres nombreux et trés longs ils pouvaient nager facilement et se transporter, rapidement peut-étre, d’un lieu & un autre; ils avaient aussi la faculté de se fixer & quelque objet, lorsqwils en avaient le désir, au moyen des crochets dont est munie Vextrémité de leurs cirrhes.” I suspect, however, that the swimming was effected rather with the arms than with the cirri, which are not used for that purpose by the Comatule, and would have to be moved with considerable power in order to effect the locomotion of the animal. The condition of so many recent species is a strong argument in favour of the views formerly expressed by Buckland® and others regarding the possible locomotive powers of the Liassic Pentacrinide, though they have been somewhat discredited of late. Now too that their recent representatives have been found so abundantly in depths of less than 100 fathoms, instead of being exclusively abyssal types as was once supposed, the 1 Encriniden, p. 271. 2 Notice sur le Pentacrinus de Sennecey-le-Grand, Chalon-sur-Saone, 1878, p. 12. 3 Geology and Mineralogy, vol. i.’p. 437. REPORT ON THE CRINOIDEA. 23 possibility of their becoming attached to floating timber does not seem so very distant after all. They may have been attached above by a slightly spreading base as on the modern telegraph cables; or, on the other hand, they may have been drifted in large numbers by the currents after detaching themselves from their original base of attachment. Occupying the innermost part of the stem of a Pentacrinite, and lodged within its central canal, is its internal vascular axis (Pl. XXIV. figs. 1-5; PI. LXII.). This consists of five peripheral vessels arranged around a central one. The former Pl. XXIV. figs. 2-5; Pl. LVIII. fig. 3—ch’) are downward extensions from the chambers of the quinquelocular organ within the calyx (Pl. XXIV. figs. 6-8; Pl. LVIII. figs. 1-3—ch; Pl. LXII.); while the latter (Pl. XXIV. figs. 2-5, v.) is similarly connected with the axial vessel or vessels of the chambered organ (Pl. XXIV. fig. 6; Pl. LVIII. figs. 1-3—»v.; Pl. LXII.). This central vessel does not increase in size at the nodes, where the peripheral vessels expand considerably, so as to form a miniature chambered organ (Pl. XXIV. figs. 3, 4, ch.n.); and each chamber gives off one cirrus- vessel (fig. 4, cv.). The fibrillar sheath around the chambered organ in the calyx (PL XXIV. figs. 6,7; Pl. LVIII. fig. 1—ca; Pl. LXII.) is continued down the stem, around its vascular axis (Pl. XXIV. figs. 1-5, ca; Pl. LVIIL. fig. 3; Pl LXII). It is sometimes closely surrounded by a more or less complete ring of pigment masses, stmilar to those which occur in the surrounding tissue (Pl. XXIV. figs. 2, 5, p.); but in other parts of the same stem these are absent in the immediate neighbourhood of the central axis (figs. 3, 4). Radiating extensions of the latter are frequently to be seen (fig. 1. fig. 2, ca’). They proceed outwards into the organic basis of the skeleton, and then become lost, though they probably reach the epidermis, like the similar branches from the axial cords of the arms and pinnules, to which a nervous nature has long been attributed. B. BourGuETICcRINIDA. The type of stem which occurs in this family differs in many respects from that characteristic of the Pentacrinidee. The joints are very variable in their relative propor- tions, instead of being uniformly discoidal; they never form syzygial unions, but are freely movable upon one another, and are connected by successive pairs of ligamentous bundles instead of being strung, as it were, upon five tendons of variable length. In the only two recent genera which belong to this family, Bathycrinus and Rluzocrinus, one or more of the young upper stem-joints are simple circular disks, with little or no markings of any kind upon their terminal faces (PI. VII. figs. 1-3, 11; PieVilinehers—oe bh Villa ne. > Pl IX. fies, 13; PL X. figs. 2,9, 10; PL LE figs. 7, 8). But lower down the stem the joints become first cuboidal and then elongated, so that their length may be two or three times their diameter (PI. VII. figs. 1, 10; Pl. Villa. figs. 2, 3; Pl. IX. figs, 1, 3; Pl. LIII. figs. 7,8). The younger of these elongated joints are simply cylindrical ; but the older ones are more dice-box shaped with 24 THE VOYAGE OF H.M.S. CHALLENGER. expanded ends, while the articular ridges in the long axes of the terminal faces cross one another at various angles. This mode of articulation is common to all the Bourgueticrinide, though the stem- joints are not always so long as in Rhizocrinus and Bathycrinus. It oceurs also in the curious genus Thiolliericrinus and in the stem of the larval Comatula. Both Thiollieri- crinus and Bourgueticrinus occur in the Jurassic rocks ; while the same kind of column as occurs in these genera existed also in the Carboniferous Platycrinus, and according to Messrs. Wachsmuth and Springer’ “forms one of the most characteristic features of the genus.” There is a considerable amount of variation among the different members of the Bourgueticrinidee in the characters of the terminal faces of the stem-joints. In the Jurassic genus Thiolliericrinus, in Bourgueticrinus (Jurassic and Cretaceous), and in the Cretaceous Mesocrinus the articular ridge is narrow and linear, expanding somewhat around the opening of the central canal to form the real articular surface. ” In all these genera a median groove extends along each half of the ridge, from the central opening towards the margin of the joint face ; and short shallow branches proceed from it on either side so as to cut out the upper portion of the ridge into a double row of small teeth. In Thiolliericrinus, Mesocrinus, and Bourgueticrinus ellipticus the ligament-fosse at the sides of the articular ridge are either uniformly shallow throughout their whole extent, or they are deepest in the immediate neighbourhood of the central canal. But they are completely separated from one another by the articular ridge, which is continuous from end to end of the elliptical surface. Very much the same is the case in the upper and middle stem-joints of Bathycrinus (Pl. VIla. figs. 8, 9), except that the articular ridge is relatively larger and is destitute of teeth. But in the lowest stem-joints of this genus (Pl. VII. figs. 12, 13; Pl. Vila. fig. 11), and in all parts of the stem of Rhizocrinus (Pl. X. figs, 11-14), the articular surface is incomplete, and instead of surrounding the central canal, is actually divided by it into two trihedral portions, the upper edges of which are toothed just like the corresponding parts of the complete ridge in Bourgueti- erinus ellipticus or Mesocrinus. The two ligament-fossee communicate with one another around the opening of the central canal, which thus appears to lie at the bottom of a deep depression. Quenstedt ° figures some stem-joints of this kind from the white chalk of Riigen under the name of Apiocrinus constrictus. 1 Revision of the Paleocrinoidea, part ii., Proc. Acad. Nat. Sci. Philad., 1881, p. 69 (243). * In a stem-joint from the Mestricht Chalk, which is figured by Quenstedt as Apiocrinus (Bourgueticrinus) ellipticus (Encriniden, Tab. 104, fig. 70), there is no articular ridge at all, but merely an oval articular surface around the opening of the central canal. Unless this be the result of an accidental removal of the ends of the articular ridge, it is a somewhat striking peculiarity which tends te approach the condition of the middle stem- joints in Bathycrinus, and has a still closer resemblance to a form of articular surface which is especially characteristic of the cirrus-joints (ante, pp. 7, 8). 3 Encriniden, Tab. 104, figs. 64-66. REPORT ON THE CRINOIDEA. 25 While the general characters of the stem are identical in Rhizocrinus and Bathy- erinus, there is a good deal of variation in its details, and especially in the mode of growth. In all cases the new joints are added at the top of the stem, immediately beneath the cup ; but the rate at which they increase in length is very different in the different species. It appears from Sars’s figures,’ and from my own observations, that the pro- duction of new joints in the stem of Rhizocrinus lofotensis is slow compared to their subsequent increase in length. For there are very rarely more than three joints beneath the cup which are wider than high, and even these have an appreciable thickness (Pl. IX. figs. 1, 2; Pl X. fig. 1). Sars remarks of the uppermost one that it is “annulaire et a 2 ou 3 et méme souvent 5 ou 6 fois plus de largeur que de hauteur ;” while there are usually not more than eight cylindrical joints beneath it. Below this limit the jomts have the well-known dice-box shape, with the characteristic terminal faces, the peculiarities of which begin to appear very few joints below the cup. Most individuals of Rhizocrinus rawsoni seem to be generally similar to Rhizocrinus lofotensis in these characters (Pl. IX. fig. 3; Pl. LIII. figs. 7, 8). But in one example I found five joints beneath the cup which were wider than high. The second and third are mere circular disks with perfectly plain faces like those of the fourth (Pl. X. fig. 10) ; and the faces of the newly formed joints of Rhizocrinus lofotensis which are figured by Sars? are of the same nature. But the uppermost joint of all is of a different character altogether (Pl. X. fig. 9). It has a pentagonal outline, and its surface, which rises gradually from the circumference towards the centre, is divided by five radiating ridges into an equal number of trapezoidal fossee that receive the lower ends of the elongated basals (Pl. X. figs. 3, 5). Here, therefore, we find the top stem-joint presenting the same characters that it does in Apiocrinus* and Millericrinus,‘ and entering to some extent into the composition of the cup, while the new joints are probably intercalated below it. Quenstedt°® speaks of this uppermost stem-joint in the Apiocrinid indif- ferently as “Endstiick, Endsiiulenglied, or Fiinfrippenglied.” De Loriol® has named it “article basal ;’ while Zittel’ speaks of it as the “ Centro-dorsal,” and remarks “ Dasselbe scheint, wie aus der Andeutung von Nihten hervorgeht, aus 5 urspriinglich getrennten Stiicken entstanden zu sein und entspricht wahrscheinlich den 5 Infrabasalpliittchen bei Encrinus.” It is perhaps a little expedient to employ the term “ centro-dorsal” for a joint which bears no cirri, as its similarly named homologue does in the Comatule. 1 Mémoires pour servir 4 la connaissance des Crinoides vivants. 1. Du Rhizocrinus lofotensis, tab. i., ii. 2 Op. cit., tab. ii., figs. 20-22. 3 D’Orbigny, Histoire Naturelle, générale et particulitre des Crinoides vivans et fossiles., pl. ii. fig. 3, pl. iii, fig. 4, pl. v. fig. 4. * Ibid., pl. xiv. figs. 15, 23, 24; and Quart. Journ. Geol. Soc., vol. xxxviii. p. 33, pl. i. 5 Eneriniden, pp. 314, 315. 6 Swiss Crinoids, p. 4; Paléont. Frang., loc. vit., p. 19. 7 Handbuch der Paleontologie. Palzozoologie, Bd. i., pp. 388-390. (ZOOL, CHALL, EXP.—PART xxxIr.—1884.) Ti 4 26 THE VOYAGE OF H.M.S. CHALLENGER. But I should prefer doing this to using a name, as de Loriol has done, which is so very similar to that universally employed to designate some of the calyx plates, although there is no sort of homology between the two structures. This latter point is recognised by de Loriol, who makes it clear that he regards the “article basal” as a stem-joint. Whatever may be the case in Apiocrinus, this plate is single in Rhizocrinus rawsoni (Pl. X. fig. 9), and I cannot help suspecting that Zittel has been misled by the appearance of sutures into regarding it as probably consisting of five coalesced under-basals. I have noted a somewhat similar condition in Millericrinus pratti.’ Owing to the larger number of discoidal joints in the stem of Rhizocrinus rawsoni than in that of Rhizocrinus lofotensis, the gradual development of their articular faces is more easily made out in the former species. As the joints become longer than wide, shallow fosse appear to the right and left of the opening of the central canal, which thus seems to be the deep middle portion of an oval depression occupying the shorter axis of the elliptical face (Pl. X. fig. 12). These fossee gradually increase in relative size, and encroach more and more upon the original plane surface of the joint face, still, however, remaining in connection with one another around the central canal (Pl. X. figs. 11, 13, 14). They reach nearly to the margin of the joint face, so as to leave a small articular rim outside them ; but they do not reach so far in the direction of the long axis, at the ends of which the original surface of the jomt remains to form the so-called “articular ridge.” This is, however, by no means continuous across the opening of the central canal, as is implied by its name; for it is merely represented by two triangular surfaces which encroach upon the original oval depression so that it assumes the form of a rather short-handled dumb-bell (Pl. X. figs. 11, 18, 14). The two ends slope rapidly downwards towards the centre, where the opening of the axial canal is situated. It thus establishes a connection between the two fosse and interrupts the continuity of the articular ridge. This type of joimt-face also occurs in the lowest part of the stem of Bathycrinus (Pl. Vila. figs. 10, 11), but it is the result of a different mode of growth altogether. There are several thin discoidal joints at the top of the stem (PI. VIL. figs. 1-3, 11; Pl. Villa. fig. 1), and the uppermost one, on which the basals rest, has its surface marked by a ten-rayed depression which extends outwards from the five-lobed opening of the central canal (Pl. VIIa. fig. 3). The corresponding face of the basal ring is marked in the same manner (figs. 13, 14); and the fossze lodge the five horse-shoe shaped ligamentous bundles which unite the basals to the stem-joints below them. On the upper face of the second joint, however, the opening of the central canal is surrounded by a raised articular rim, still showing traces of fosse like those on the top joint, and this rim is more marked on the next few joints (figs. 4, 5). As the joints below become thicker and their terminal faces more oval, the articular rim also 1 On some new or little known Jurassic Crinoids, Quart. Jowrn. Geol. Soc., vol. xxxvili. p. 34. REPORT ON THE CRINOIDEA. 27 assumes an oval form, and the ten markings on its edge first become arranged into two groups of five each (fig. 5), and then finally disappear (fig. 6). This is due to the five ligamentous bundles mentioned above as being attached to the basals, becoming gradually replaced by the two larger and somewhat crescentic bundles which unite the joints lower down the stem. The articular rim eventually becomes restricted to a broad ridge which occupies the short axis of the oval oblong face, and is pierced in the centre by the oval opening of the central canal (figs. 7, 8). In the slender joints of the upper third of the stem (fig. 7) this: ridge takes up the greater part of the articular surface, and there is merely a shallow fossa on either side of it. As the joints increase in stoutness the ridge becomes relatively narrower, and the lateral fossze proportionately larger (figs. 8, 9). They are shallowest at the edge, and gradually deepen as they approach the ridge. When the joints begin to shorten again but continue to increase in stoutness, their terminal faces become more circular (fig. 10), though the planes of the articular ridges at the two ends of each joint still continue to cross one another. The ridges themselves still diminish in relative width, and become somewhat constricted in the middle, until there is only a very narrow rim around the opening of the central canal (figs. 9, 10). Lower down the stem this rim disappears altogether (PI. VII. figs. 12, 13; Pl. VIla. fig. 11), so that the two lateral fossee communicate around the central opening just as in Rhizocrinus (Pl. X. figs. 11-14). The joint-faces also become oval again, and the articular ridges now occupy their longer axis (Pl. VIla. fig. 11) instead of the shorter ones, as is the case at the top of the stem (figs. 7-9). The two halves of each ridge which are separated by the opening of the central canal are of an elongated triangular shape, and relatively narrower than in Rhizocrinus rawsont, owing to the greater size of the lateral fossze. Hach is denticulate along its median line, as in the other Bourgueticrinide. The distinction of the lower stem-joints of Rhizocrinus and Bathycrinus thus becomes a matter of some difficulty, though those of the upper and middle parts of the stem are very different in their characters. In the young individuals of both genera most of the stem-joints are simple, more or less elongated cylinders; and the characteristic dice-box shape is only visible in a few joints immediately above the root (Pl. VIIIa. figs. 2,3; Pl LIIL. figs. 7, 8; woodcut, fig. 16, p. 244). The lower part of the stem in the Bourgueticrinide may bear a large number of irregularly branched radicular cirri, two or more proceeding from ‘each joint near the end of the long axis of one face (Pl. IX. fig. 1; Pl. X. figs. 13, 15) ; while the main axis may eventually break up into a similar set of branching rootlets. These two forms of roots may coexist in the same individual, or either may occur alone. In some specimens of Rhizocrinus lofotensis the radicular cirri are exceedingly abundant. Thus in an indivi- 28 THE VOYAGE OF H.M.S. CHALLENGER. dual figured by Sars’ they occur on the lowest thirty-three jomts of a stem with fifty- nine joints altogether. In another case five out of eighteen joints are cirriferous ; while the individual represented in Pl. IX. fig. 1 has only nine cirriferous joints in a stem of over forty. A similar variation occurs in Rhizocrinus rawsoni. Every joint in the lowest part of the stem may bear cirri at one or both ends of the long axis of its upper face. But I have in no case found more than fifteen joints in this condition, and they are sometimes not consecutive, a cirrus-less joint being occasionally interposed between two others which bear cirri (Pl. X. fig. 15). On the other hand, in the only individual with a complete stem which was obtained by the Challenger, and also in the young specimens dredged by the “ Porcupine,” there are no radicular cirri at all, but only a spreading root formed by subdivision of the main axis of the stem (Pl. LHI. fig. 7) ; and this appears to be a constant condition in Bathycrinus (Pl. VIL. figs. 1, 9; Pl. VIIa. fig. 3). Below the last of the regular and dice-box shaped joints, which may or may not bear cirri, there come one or more others of irregular shape and variable size. Spreading rootlets proceed outwards from these, as a rule more abundantly in Rhizocrinus than in Bathycrinus. In Rhizocrinus lofotensis this inferior joint usually bears several slender root filaments disposed around a central one ; while one or two stronger and branching rootlets sometimes come off between it and the regular stem-joints. This is more especially the case in Rhizocrinus rawsoni ; but in Bathycrinus the inferior joint, or “ root- joint” as it has been called, is quite short, and gives off two or rarely three chief roots, which themselves subdivide into smaller ones (Pl. VII. figs. 1, 9; Pl. VIIla. fig. 3). Both these rootlets of the stem-axis itself and the radicular cirri are composed of a series of gradually diminishing joints closely united by ligaments. They attach them- selves to foreign bodies by calcareous expansions round their ends or beneath the sides on which they happen to rest (Pl. IX. fig. 1; Pl. X. fig. 15). Anything serves for this purpose which may improve the anchorage of the Crinoid in the soft mud, which is nearly universal at great depths, e.g., fragments of shell, grains of sand, sponge-spicules, foramin- iferal tests, &c. Hence, whatever be the case in the Pentacrinide, Rhizocrinus and Bathycrinus must remain permanently fixed in one place throughout life. In a specimen of Rhizocrinus rawsoni which was dredged by the “ Travailleur,” and was described as a new genus Democrinus by Perrier,’ the diameter of the stem is lessened at the origin of two groups of rootlets, and regains its former size lower down. Perrier suggests the question “si la partie qui se prolonge au dela des racines n’est pas destinée & devenir un second pédoncule surmonté d'un second calice. Si cette induction se vérifie, les Democrinus constitueront le premier exemple actuel d’Echinodermes vivant en 1 Op. cit., tab. i. fig. 1. 2 Sur un nouveau Crinoide fixé, le Democrinus Parfaiti, provenant des dragages du “ Travailleur,” Comptes rendus, t. xcvi., No. 7, pp. 450, 451: 7 ia Om “ee = , REPORT ON THE CRINOIDEA. 29 colonies et ramifiés.” I can, however, see no probability whatever in this supposition, having met with no facts confirmatory of it either in any of the numerous roots of Rhizocrinus and Bathycrinus which I have examined, or in the descriptions of these genera by Sars and Danielssen. Neither is it supported in the slightest degree by what we know of the embryology of the Crinoids. Prof. Perrier has suggested some further views of the morphology of the stem which I find myself unable to accept. He begins by saying “ De tous les Crinoides fixés actuels, les Democrinus sont ceux chez qui les dimensions transversales du calice sont le plus foibles par rapport au diamétre du pédoncule.” I am indebted to his kindness for the following measurements of his specimens— Length of the calyx from the terminal furrow to the top stem-joint, . : 9 mm. Maximum diameter of the calyx, : 6 5 ‘ : 4 Py es Diameter of the stem-joints, . : é - f 5 5 Ly 5 That is to say, the diameter of the calyx does not exceed twice that of the stem-joints. But at the time Prof. Perrier made the statement quoted above he had before him the following measurements of the calyx and stem in three varieties of Rhizocrinus rawsoni— Basal tube. Stem-joints diameter. 1. Blake, . ; ; SOs o) e200) mm. 2°25 mm. 2. Challenger, F : 5 BAO) Se PAOLO 2:00; 3. Porcupine, 5 : 5) SiO) Se Alera ss Te2Dn ss Hence the maximum width of the calyx in the Challenger specimens of Rhizocrinus rawsoni is the same as that of the largest stem-joints ; while the proportion is as 2: 1 im the so-called Democrinus, and this is not attained by the calyx, either of the “ Blake” or of the “Porcupine” specimens. It seems to me that the calyx of Democrinus is larger relatively to the stem than in any of the Crinoids most nearly allied to it (instead of being narrow as stated by Prof. Perrier), who proceeds as follows :—“Si l'on songe que, chez les Echinodermes libres actuels, le corps tout entier ne représente que le calice des Crinoides fixés surmonté de ses bras, on est étonné de voir une partie qui est absolument nulle chez les représentants des autres groupes prendre chez les Democrinus un développement tel qu’elle représente cing 4 six fois au moins le volume du corps propre- ment dit. Ce fait seul nous avertit que le pédoncule doit étre pris en grande considération pour la détermination de la forme fondamentale des Kchinodermes. Chez les Demo- crinus, il produit un appareil radiculaire formé de rameaux articulés ramifiés ayant la méme structure que lui-méme et présentant des dimensions supérieures & celles des bras ; cet appareil ne saurait étre davantage négligé au point de vue morphologique, et l’on est conduit \ considérer ses diverses branches comme ayant la méme valeur que le pédoncule lui-méme dont elles ont la structure.” A far better instance than Democrinus of disproportion between stem and head is 30 THE VOYAGE OF H.M.S. CHALLENGER. furnished by the Liassic Evtracrinus, the stem of Extracrinus subangularis reaching a length of 50 to 70 feet. But even as regards Democrinus I cannot admit that the dimensions of the stem are so much greater than those of the arms. This may indeed be the case in Perrier’s three specimens, of which “deux sont totalement dépourvus de bras ; le troisiéme n’en présente que des restes trés courts, d’aprés lesquels il est aisé de voir que les bras devaient étre extreémement peu développés.” But in the Carribbean examples of Rhizocrinus rawsont the longest stem (180 mm.) contains sixty-eight joints above the root, while there are five arms, each consisting of about eighty joints. Nearly half of these bear pinnules, so that even if the radicular part of the stem is taken into account, the superior dimensions would seem to be on the side of the arms rather than on that of the stem, which Perrier considers to represent five or six times the volume of the calyx and arms together. It is likely enough that this may have been true in his three specimens of Demo- erinus, which had lost the whole or greater part of their arms, owing to fracture at the syzygies, as is only too often the case with both species of Rhizocrinus. But when a tolerably perfect individual is obtained the arms are found to be considerably more than “extremement peu développés,” as was so easily inferred by Perrier upon totally insufficient evidence. He goes on to say, “ Alors méme qu’ils ne vivraient pas en colonie, le volume considérable de leurs racines ramifiées, la ressemblance de ces racines avec les bras qui surmontent le calice et dont elles sont probablement homologues, suffisent i démontrer que la disposition arborescente des parties, préface en quelque sorte de la symmétrie radiaire, n’est pas plus étrangére au type des Kchinodermes qu’au type des Ceelentérés.” The relationship of the Echinoderms to the Ccelenterates need not be discussed here ; but the resemblance and “probable homology” which Prof. Perrier sees between the arms and the root of a Crinoid appear to me to be forced in the extreme. The arms are merely extensions of the body, containing the same nerves, vessels, and body-cavity as are found in the calyx, together with the fully developed genital glands which are usually sterile in the body. But the branches of the root have the same structure as the stem, as remarked by Perrier himself; and this is very different from that of the cup and arms. It is true that the rootlets, like the arms, are traversed by axial cords which are connected with the fibrillar envelope of the chambered organ; but there the resemblance ends. They support no soft parts as the joints of the arms and pinnules do; and being formed entirely on the right antimer are totally devoid of any of the ambu- lacral structures which are so important in the morphology of the arms. If the term “homologous” is to be employed for a mere superficial resemblance of this kind, a new word must be introduced to denote community of origin and morphological similarity. One might almost as reasonably say that the quills on the back of a porcupine are homologous with its limbs. REPORT ON THE CRINOIDEA, 31 Both in Bathycrinus and in Rhizocrinus the organic and calcareous networks, which interpenetrate one another, are not always perfectly continuous throughout the substance of the stem-jomts. For both in optical and in transverse sections of de- calcified stems empty spaces are often visible, especially in the immediate neighbourhood of the central axis. Five of these spaces appear in some of my transverse sections of the lower stem-joints of Bathycrinus (Pl. VIIa. fig. 2, rs). They are radially disposed, being situated immediately outside the five peripheral vessels of the central axis (ch’), which they may not greatly exceed in size. Both spaces and vessels may contain larger or smaller masses of pigment granules (p). The walls of the former are less well-defined than those of the latter, but are distinctly sharper than the outlines of the spaces in the organic plexus forming the remainder of the stem-joint. It sometimes happens in the lower part of the stem that one of these spaces may increase very greatly in size, and so displace the central axis from its median position ; or the space may approach quite near to the surface of the jot. They are much more irregular in the lower part of the stem than in the uppermost elongated joints, where they are also of larger relative size (Pl. VIIa. fig. 1, 7s); and they appear to communicate with one another from joint to joint, through the elongated oval opening of the central canal (Pl. VIla. fig. 7). But there is nothing to be seen of them in the discoidal joints at the upper part of the stem, which are continuously traversed by closely set ligamentous fibres (Pl. VIIb. fig. 1). The best preparations that I have been able to obtain illustrative of this point have been from the stem of Bathycrinus ; but I have also seen these spaces, though not so well, in Rhizocrinus. The former genus (or at any rate Bathycrinus aldrichianus) is remarkable for the abundance of delicate fibrils which may be seen proceeding outwards from the central fibrillar axis of the stem, the nervous nature of which is gradually coming to be recognised. Some of the larger of these fibrils are shown in optical section in Pl. VIIa. fig. 1, ca’. But a much larger number of smaller ones may be seen with a high power. They leave the central axis in a more or less transverse direction, and form an open plexus, im- mediately beneath the external surface of the stem. This is most distinctly seen over the radial spaces, where the decalcified stem is, of course, more transparent than else- where. It is noteworthy that the arms of Bathycrinus aldrichianus, like the stem, are also remarkable for the large number of branches which proceed outwards from their axial cords (Pl. Vb. figs. 6, 7; Pl. VIIa. figs. 4, 5—a’). The corresponding branches in the stem of Pentacrinus have been already noticed (ante, p. 23). C. Hyocrrmip&. The stem of Hyocrinus is one of considerable interest, because it is the only recent Crinoid in which the terminal faces of the stem-joints are of the same nature as those of 32 THE VOYAGE OF H.M.S. CHALLENGER. the Apiocrinide and of so many of the Palzocrinoids. The applied surfaces of the cylin- drical joints, forming the lowest portion of the stem with which we are acquainted, were described by Sir Wyville Thomson * as “being marked with a pattern of radiating grooves and ridges.” There appears, however, to be a good deal of variation in this respect ; for, while some of the joint-faces have the radiating pattern very well developed, others are perfectly plain (PI. Ve. fig. 4), and others have only slight indications of the striation. But the radiating strie never “resemble minute pores penetrating the walls,” as stated by Wachsmuth and Springer,’ of the similarly marked joint-faces in the Paleeocrinoids. The stem of Hyocrinus is much more rigid than that of the Bourgueticrinide. The short cylindrical joints are united by uniformly disposed ligaments (PI. Ve. fig. 5, 7s), the fibres of which are all of equal length and not longest in the centre as in the oldest parts of the stem of Bathycrinus and Rhizocrinus. The ligamentous fibres at each end of the joint extend into its substance for about one-fifth of its length, so that the calcareous tissue is closer towards the ends than in the median parts of the joints. These contain radial spaces (Pl. Ve. fig. 5, rs) of the same nature as those just described in the Bourgueticrinidee (Pl. VIIa. figs. 1, 2, 7s). So far as I can make out from the only two fragments of stém which have reached me, measuring 70 and 85 mm. respectively, there are a large number of discoidal joints at the top of the stem (PI. VI. figs. 1-3). Their thickness gradually increases from above downwards, until they are about half as long again as wide. The length then diminishes again and the width increases, rising im one example from 1 mm. to nearly 1°5 mm. within twelve joints. The lower joints thus become more discoidal again, like those some little way below the calyx. What they were in the stem-fragment, 170 mm. long, which is mentioned by Sir Wyville Thomson, I have no means of knowing. Neither are we acquainted with the nature of the actual base of attachment. 1 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p. 52, 1878. ? Revision, part i. p. 14. REPORT ON THE ORINOIDEA. 33 Iil.—THE CALYX. In all the recent Crinoids, with the single exception of Thawmatocrinus (P]. LVI. figs. 1-4), the calyx proper is formed of but two series of plates, viz., the basals, which rest upon the top stem-joints, and the radials, which are supported by and alternate with the basals. The plates of these two series are suturally united to their fellows and to one another; and they enclose a central cavity which is sometimes large enough to contain the whole visceral mass, as in Holopus (Pls. I-IV.) and Hyocrinus (Pl. VI). In other cases, however, the internal cavity of the calyx is reduced to a minimum, and it lodges nothing but the chambered organ with the plexiform gland which rises from it ; while the entire visceral mass is situated altogether above it, and is very easily detached from it, as in many Comatule, so that there can hardly be said to be any cup at all. Intermediate conditions between these two extremes are met with im the Bourgueti- crinidee and Pentacrinide. In the last named family the cup which is formed by the united upper surfaces of the radials is wider than in Antedon, but somewhat more hollowed than in Actinometra (Pl. XII. figs. 1, 2, 15, 16; Pl. XVII. fies745, 5)25 Pla XOK: figs. 5,8; Pl. XXVI. fig. 11; Pl. XXX. figs. 3, 4; Pl. XXXII. figs 556 Pl UX, figs. 7,8; Pl. L. figs. 5, 6); and the lowest portion of the visceral mass rests in this concave upper surface of the radial pentagon ; while the greater part of it lies in the cup which is formed by the outer radials and lowest distichals (P]. XVI. fig. 5; Pl. L. fig. 1; Pl. LXII.). But the central funnel of the calyx, which is between the inner faces of the radials, only contains the plexiform gland ascending from the chambered organ (Pl. LVIII. fig. 3, ~). This is also the case in Rhizocrinus and Bathycrinus (Pl. VIIb. figs. 1, 4, 5, x). In the former genus the upper surface of the calyx has a deep hollow which lodges a portion of the intestinal coil (Pl. X. figs. 1, 4, 6, 7, 8); while the upper part of the visceral mass is entirely supported by the first four brachials in two syzygial pairs (Pl. X. figs. 2, 20). In Bathycrinus, however, the gut hardly descends to the level of the first radials ; and though the visceral mass is very largely supported by the large wing-like processes of the axillaries, it is practically quite free from the lowest brachials (Pl. VII. fig. 3;, Pl. VIIb. figs. 1, 7, 8). Concealed in the lower portion of the calyx is the chambered organ, the position of which, relatively to the calyx-plates, varies considerably. In all the Comatule it is lodged within the cavity of the centro-dorsal, and it is therefore entirely on the dorsal side both of the radials and of the basals, whether the latter have been metamorphosed into a rosette or not. But in the stalked Crinoids there is no enlargement of the central canal of the stem within its uppermost joint, and the vascular axis passes up into the calyx before expanding to form the chambered organ. In Rhizocrinus, Bathyerinus, and (z00L, CHALL. EXP.—PART xxxu1.-—1884.) id 34 THE VOYAGE OF H.M.S. CHALLENGER. Pentacrinus this expansion takes place near the top of, but entirely within the basal ring, the radials having no share in the protection of the chambered organ, though they surround the lowest portion of the plexiform gland which rises out of it (Pl. VIIb. festa <4, 53° PL Villa. figs 67s Pie Oxy. ffigs, -7=9 > Pl Vee es Pl. LXII.). Within this central funnel of the radials, and closely enveloping the plexiform gland, is a kind of plug formed by numerous irregular limestone bars which are developed from the inner faces of the radials. In Bathycrinus it is practically little more than calcified connective tissue (Pl. VIIb. figs. 1, 4, 5, c), but it becomes very solid in Rhizocrinus, and has been wrongly described as a basal rosette (Pl. VIla. fig. 7 ; Pl. X. figs. 1, 4,br.). It isalso well developed in Pentacrinus (Pl. XXIV. figs. 8, 9, ”p.), and is lodged in a small depression upon the upper surface of the basal ring, which is formed by the truncation of the inner ends of its component pieces (Pl. XX. figs. 2-6, 9). Among the Apiocrinide the cavity which lodged the chambered organ is bounded in varying proportions by the basals and radials. In some species, such as Millericrinus milleri, this structure must have lain altogether upon the ventral aspect of the basals. These form a complete ring, just as in the aberrant Comatule, Atelecrinus and Thaumatocrinus; but in both these types the basal ring is on the ventral side of the chambered organ, which is precisely the opposite condition to that of Millericrinus nulleri. A. Tue Basats. The basals of the Neocrinoidea vary considerably in the extent to which they are developed. In all the Paleocrinoids the radials are separated from the top stem-joint by one complete ring of plates, to which a second is often added. But in the Neocrinoids no basals may be visible at all upon the exterior of the calyx, as in most Comatule ; or there may be a single complete ring of high plates as in Rhizocrinus (Pl. IX. figs. 1-3 ; Pl. X. figs. 2,3; Pl LIII. figs. 7, 8); or there may be two rows of plates of variable size as in Encrinus, Extracrinus, and Marsupites. The absence of external basals in most recent Comatulz is due to their having undergone metamorphosis into the well-known rosette, which is concealed between the centro-dorsal and the radials. But the occurrence of this condition in a stalked Crinoid would appear somewhat improbable. Personal examination has convinced me that in two cases’ at any rate the supposed absence of basals in fossil Pentacrinidee is merely the result of defective observations ; but this may not be invariably true. No basals are visible externally in the Jurassic Isocrinus pendulus, Meyer,’ nor in the Pentacrinus pentagonalis personatus from the Brown Jura, which is figured by Quenstedt* without 1 These are (1) Pentacrinus fisheri, Forbes, from the Kimmeridge Clay of Weymouth ; and (2) a fine specimen from the Chalk, which is figured in Dixon’s Geology of Sussex (1878 edition, pl. xix. 22). * Tsocrinus und Chelocrinus, Museum Senckenbergianum, Frankfurt, 1837, Taf. xvi. figs. 1, 2. 3 Encriniden, Tab. 98, fig. 137. REPORT ON THE CRINOIDEA 35 any notice of its peculiarities. They likewise appear to be absent in the Forest-Marble specimen from Farley in Wiltshire, which was described by Goldfuss as Pentacrinus scalaris ;* while they are certainly absent externally in one of the two known specimens of Metacrinus costatus, though fully developed in the other (Pl. XLIX. figs. 1, 2). This is a most curious anomaly; but as the specimen cannot be sacrificed to investigation, it is impossible to ascertain whether the basals are absent entirely, or whether they have been metamorphosed into a rosette. It is possible that they are so greatly reduced in size as to fail to appear externally, as occasionally happens in Hnerinus and in the fossil Comatule, which retain their embryonic basals in an unmetamorphosed condition.? They are sometimes quite small and insignificant in comparison with the radials, asin the Liassic Pentacrinus tuberculatus, and in some varieties of the recent Pentacrinus decorus (Pls. XXXIV.-XXXVL). In these and similar forms they appear at the lower angles of the calyx as minute rounded plates, between which the lower edges of the radials rest directly upon the top stem- joints. The basals are therefore only in contact with one another by their inner ends (Pl. XXXIV. fig. 8). But in other species, both recent and fossil, they are considerably larger, and their outer ends separate the radials more completely from the top stem-joint (Pl. XIII. fig. 1; Pl. XV. fig. 2); while the union of their inner ends is more extensive Pl. XIL fig. 16; Pl. XXVI. fig. 11). In fact all degrees of union may be traced (both in different species and in different individuals of the same species) from the condition of Pentacrinus blaker and Pentacrinus decorus (Pls. XXXI., XXXV.) to that of Pentacrinus wyville-thomsoni and Pentacrinus maclearanus, in which the radials are separated from the top stem-joint by a ring of large and closely-united basals (Pls. XVI, XIX. figs. 1, 6, 7). The genus Caznocrinus of Edward Forbes has been lately revived by de Loriol 3 for a few fossil species which possess a closed basal ring, but are not otherwise different from Pentacrinus. The condition of the recent Pentacrinidee, however, is such as to entirely preclude the possibility of employing this very variable character as a generic distinction. A similar series of gradations is to be met with among the fossil Comatule, in which group there appears to be much more individual variation than among the Pentacrinidz. In some few species no basals are visible externally at all. In others, the outer ends of small prismatic rods may appear at some angles of the calyx but not at others, while their inner ends do not meet at all or only very slightly so. In some species again, the outer ends of the basal rods are smaller than the inner ends, which meet together and entirely separate the median portion of the radial pentagon from the centro-dorsal beneath, Lastly, in a chalk Comatula mentioned by Schliiter* 1 Petrefacta Germaniz, vol. i. pl. lx. fig. 10. 2 On the genus Solanocrinus, Goldfuss, and its Relations to recent Comatule, Journ Linn. Soc. Lond. Zool., vol. xv. pp. 211, 212. 3 Swiss Fossil Crinoids, pp. 111, 112. Ueber einige astylide Crinoiden, Zeitschr. d. deutsch. geol. Gesellsch., 1878, p. 66. 36 THE VOYAGE OF H.M.S. CHALLENGER. there is a complete ring of united basals as in the recent genera Atelecrinus and Thaumatocrinus (Pl. LVI. figs. 1-4). In the four other genera of recent Comatulidee, however, the primary embryonic basals undergo transformation into the well-known rosette, which is really a secondary structure. It lies over the chambered organ, between the under surface of the radial pentagon and the, upper face of the centro-dorsal ; but it is entirely concealed, and does not appear at all upon the exterior of the calyx. In many Comatulez more or less prismatic rods proceed outwards from the inter- radial angles of the rosette, and their ends are often visible on the exterior of the calyx. They occupy exactly the same positions as the rod-like basals of many fossil Comatulz, but do not represent them morphologically, for they are not developed from the primary embryonic basals. These last become transformed into the rosette, which is a secondary structure as shown by Dr. Carpenter ;' while the tertiary basals which are connected with its interradial angles are merely ossifications in the connective tissue of the synostosis between the radials and the centro-dorsal, and are somewhat variable in their development.” They do not occur in Antedon rosacea, nor in the species on both sides of the Atlantic which are most nearly allied to it, viz., Autedon phalangium, Antedon dentata, Antedon hageni, &c.; and they seem to be absent in Eudiocrinus, at any rate in Hudiocrinus semperi. But they reach a relatively large size in many tropical species both of Antedon and of Actinometra, in which latter genus I have never found them to be absent, and they also occur in Promachocrinus see fig. 1, A on p. 37). [See Note B. s p B. Tue RaApImALs. There is considerable variation in the degree of lateral union between the individual basals and radials of stalked Crinoids. Those of Holopus (Pls. I-IV.) are so intimately fused that the sutures are entirely invisible on the exterior of the tubular calyx. In Hyocrinus (Pl. VI.) the interradial sutures are quite evident, but those between the basals are very obscure. In Rhizocrinus, and especially in Rhizocrinus lofotensis, the sutures between the basals are usually entirely invisible, not only externally but also in transverse sections of the decalcified calyx; while the basiradial and interradial sutures are merely indicated by very faint lines on the surface of the cup (Pl. IX. figs. 1, 2); and strong measures are necessary before the individual jomts will separate from one another. In the Pentacrinide and Comatulide the union between the radials is less close and the sutures well defined, while the condition of the basals varies accord- ing to circumstances (Pl. XIII. fig. 1; Pl. XV. figs. 1,2; Pl. XVI.; Pl. XX. ; Pl. XXXIIT. figs. 8-10; Pls. XXXV.-XXXVII.; Pl. XXXIX.; Pl XLIII.). The union of the 1 Phil. Trans., 1866, pp. 744, 745. 2 The genus Actinometra, Trans. Linn. Soc. Lond. (Zool.), vol. ii. pp. 98-105 ; and the genus Solanocrinus, Journ. Linn. Soc. Lond. (Zool.), vol. xv., 1880, pp. 212-214. REPORT ON THE CRINOIDEA. 37 basals of Bathycrinus is extremely close, and in old individuals no sutures are visible externally (Pl. VII. figs. 1, 2, 11; Pl. VIIa. figs. 12-14), though they appear in transverse section (Pl. VIIb. fig. 2) and also in young examples. I have never suc- ceeded, however, in separating the plates from one another by the usual methods. The radials of Bathycrinus, on the other hand, are much less closely united. They are thin plates in contact with one another by quite narrow sides (Pl. VIL. figs. 6, 6a). Those of Bathycrinus aldrichianus were described by Sir Wyville Thomson as being “ often free ; but in old examples they also are frequently anchylosed into a funnel-shaped piece.” All the specimens which I have examined are in the latter condition, though the plates are readily separable. But I do not think it possible that they could ever be perfectly free as the other two radials are; and I have always found them to be closely united by ligaments up to the level of the circular commissure (Pl. VIIb. fig. 4,7), though they become much more free near the top of the calyx (Pl. VIIb. fig. 5). The Fic. 1.—Pronachocrinus kerguelensis. Calyx, x 6. A. Side view, showing the alternation of the five primary radials with the five others, which are separated from the centro- dorsal by the rays of the basal star. B. Upper view, showing the interior of the central funnel formed by the radials. difference between the “free” and the “anchylosed” conditions is probably only due to variations in the extent to which limestone is deposited around the fibres of the above mentioned interradial ligaments. The difference between the basal and radial rings in the amount of lateral union (z.c., in the distinctness of the sutures) between their component joints, which is more or less evident in Hyocrinus, Bathycrinus, and Rhizocrinus, appears also in some fossil Crinoids. Beyrich has pointed out? that in young individuals of Enerinus gracilis the sutures between the basals are invisible, although those between the radials are distinct enough ; and the same character has been noticed by Mr. R. Etheridge, jun., and myself as occurring in the Palzeozoic Allagecrinus austini.3 ? Journ. Linn. Soc. Lond. (Zool)., vol. xvi. p. 50. * Ueber die Crinoiden des Muschelkalks, Berlin, 1857, p. 44. * On Allagecrinus, the representative of a new family from the Carboniferous Limestone Series of Scotland, Ann. and Mag. Nat. Hist., ser. 5, 1881, vol. vii. pp. 285-288. 38 THE VOYAGE OF H.M.S. CHALLENGER. The second brachials of Rhizocrinus (Pl. VIIIa. fig. 8, B;), and the second radials of Bathycrinus (Pl. Vib. fig. 6, A.) are in contact by their lower edges, but soon become entirely free from one another (Pl. VII.; Pl. VIII. figs. 1, 2; Pl. TX. figs. 1-3; Pl. X. figs. 1, 2, 6-8); while the corresponding plates in Hyocrinus (Pl. VI.) are absolutely free. But in many Crinoids the second radials are often very closely united by ligamentous bundles. These are lodged in fossee at the sides of the proximal face which is not quite so wide as the distal one (Pl. XII. figs. 9,10; Pl. XXI. figs. 5a, 5c). The first joints beyond every axillary are more or less closely united in the same way (Pl. XXI. figs. 3b, 4b). But the second joints and the axillaries themselves are free, ’ though often in very close contact with their neighbours, so that their apposed sides are more or less flattened (Pl. XXI. figs. 1b, 2b); and in some cases the first four or five of the free brachials have their sides flattened in this way, where they come in contact with one another and with the corresponding joints of adjacent rays (Pl. XV. fig. 2; PL XVI, fig. 1; Pl. XXXa. "fig. 8). In all the Pentacrinide there are invariably five rays. I have never met with any exception to this rule, and all the specimens of Bathycrinus that I have seen conform to it also. The original specimen of Holopus is tetramerous; while J have seen four Comatulee with the same peculiarity, and one with six rays. Four and six rays are more common in Rhizocrinus (Pl. VIIa. figs. 6, 7), and in very rare cases there may be seven. In the Comatulid genus Promachocrinus, however, ten is the normal number, but the basals are pentamerous. Only five rays extend outwards from the central rosette to appear externally beneath five of the radials (fig. 1, 4), and they must therefore be regarded as representing the primary interradii of the type. Hence those radial pieces which are not separated from the centro-dorsal by basal rays are the original embryonic radials, homologous with those of other Crinoids and of the five-rayed Star-fishes. The five others may perhaps be compared to the additional radials developed in many-armed Star-fishes, in which, however, the positions of the five primary rays are not indicated in the adult as they are in Promachocrinus. C. Tur INTERRADIALS. In almost all adult Neocrinoids the first radials meet one another all round the calyx so as to form a complete ring; and until lately this character has been regarded as one specially distinctive of the group. For in a large number of Palzeocrinoids an anal plate retains its primitive embryonic position and rests upon a basal, thus separating two of the radials and destroyimg the complete pentamerous symmetry of the calyx. A good instance of this type is the Carboniferous genus Belemnocrinus, which has a calyx very similar to that of the recent Rhizocrinus except for the presence of the intercalated anal REPORT ON THE CRINOIDEA. 39 plate. Hewxacrinus, Dichocrinus, and their allies present a similar condition. In a few genera of the Rhodocrinide, which have been grouped together into a section Rhodocrinites by Wachsmuth and Springer, the radials are not contiguous laterally; but between every two there is an interradial plate which rests on a basal below. This character, which occurs in no stalked Neocrinoid, either recent or fossil, reappears in the singular Comatulid Thawmatocrinus’ (Pl. LVI. figs. 1-4). But with this excep- tion all the primary radials of every adult Neocrinoid, recent or fossil, stalked or free, form a complete ring. Calyx-interradials are very usually present in the Palzocrinoids, helping, together with the higher orders of radials, to mcrease the size of the cup, and strengthen its walls. According to Wachsmuth and Springer? “The first interradial is always larger than any of the rest, and is situated between the upper sloping margins of the adjoining first radials, except in some species of the Rhodocrinide, in which it rests directly upon the basals, separating the ring completely. There are generally two plates in the second series, and two or three in each succeeding one.” In the Mesozoic genus Guettardicrinus, and in some species of Apiocrinus (Apioerinus martini, Apiocrinus roissyanus), there are calyx-interradials essentially similar to those of the Palocrinoids. Each series commences with a single plate resting upon the upper angles of two first radials which are truncated for its reception (see fig. 9, on p. 183). It is followed by several others, more or less irregularly arranged ; and these, together with the two outer radials, and sometimes also the two lower brachials, form the im- movable wall of a large cup just as in the Palocrinoids. No recent Crinoid presents this condition, at any rate in the adult state; though it occurs in many Ophiurids, as pointed out elsewhere.? But in all the Pentacrinide, recent and fossil,* the interradials, if present, are not calyx-plates at all, but merely small and more or less irregular plates developed in the perisome which unites the rays and their subdivisions (Pl. XIII. fig. 1; Pl. XXXI. fig. 2; Pl. XXXIV. fig. 1; Pl. XXXV. fig 7) "Pl ROR Tien t; Pl. L. fig. 1). It would seem, however, that regular calyx-interradials may appear in the early larval stages of Antedon rosacea. At any rate this is the way in which I should interpret the following statement by Sir Wyville Thomson.’ ‘In one or two cases, however, I have observed about the time of the first appearance of the anal plate, a series of five minute rounded plates developed interradially between the lower edges of the oral plates and the upper edges of the basals.” These plates therefore, separate the radials from one another all round the calyx. Their ultimate fate is uncertain. Sir 1 On a new Crinoid from the Southern Sea, Phil. Trans., 1883, pp. 919-926, pl. 71. 2 Revision, part ii. p. 12. 3 On the Apical System of Ophiurids, Quart. Journ. Micr. Sci., vol. xxiv., N.S., January 1884, p. 12. 4 See, for example, Quenstedt’s Encriniden, Tab. 101, figs. 23, 39a ; Austin’s Crinoidea, pl. xiii. fig. le; and Buckland’s Geology (Bridgewater Treatise), vol. ii., pl. lili. fig. 2. 5 Phil. Trans., 1865, p. 540. 40 THE VOYAGE OF H.M.S. CHALLENGER. Wyville made no further reference to them except to say that they sometimes remained permanently in the adult Antedon, usually in groups of three or five. These last, however, like those already noticed in Pentacrinus (Pl. XIII. fig. 1), are merely periso- matic plates developed in the tissue uniting the second radials. Good figures of them were given by Dr. Carpenter ;* and it is by no means certain that they are a further development of the primitively single plates which appear between the orals and basals, for the direct continuity of the two structures has never been definitely traced. I am inclined to believe that where they do appear in ordinary Comatule these primary calyx-interradials eventually undergo resorption like the orals and the anal plate. But they are permanent in Thawmatocrinus (Pl. LVI. figs 1-4), as are also the orals (fig. 5). This remarkable genus has five calyx-interradials which rest on basals and separate the radials just as in certain Ophiurids and in some types of the Palaeozoic Rhodocrinidee. It is much to be regretted that this extraordinarily interesting form is only represented by a single individual. For the study of the distribution of the axial cords within the calyx would have been of some importance. If Thaumatocrinus resembles the ordinary Comatule and Pentacrinidz, the circular commissure (Pl. XXIV. fig. 9, c.co., 7.co.) is formed by both interradial and intra- radial commissures which connect the paired branches of the five primary interradial cords (Pl. XXIV. figs. 7-9; Pl. LVIIL figs. 1-3—av); and the interradial commissures must traverse, or at any rate, lie upon the inner surfaces of the interradial plates. But the general embryonic characters of Thawmatocrinus lead me to think that the arrange- ment of its axial cords must be more like that which occurs in Bathycrinus. In this genus the primary cords do not fork within the basal ring, but pass upwards through it and enter more or less complete canals which are formed by the apposition of two grooves, one on each of the contiguous lateral faces of adjacent radials (Pl. VII. fig. 6a). When they reach about half the height of the radials they fork, and the resulting branches themselves form the interradial commissures, entering the radials by the apertures in their lateral faces. I cannot help suspecting that the same condition may occur in Thawmatocrinus, 1.e., that the primary interradial cords run upwards through the basals into the interradials, and there fork, one branch entering each of the two radials which are separated by the interradial lodging the primary cord. This simple condition would correspond very well with the general embryological characters of the type, as revealed in other ways. But owing to the want of material there is unfortunately but little chance of the above hypothesis being verified or disproved. While resembling the Rhodocrinites in having five large plates separating the radials, Thaumatocrinus differs from most Palocrinoids, with the exception of the Platycrinide, in the absence of any higher series of interradial plates. Except on the anal side these 1 Phil. Trans., 1866, pl. xxxili. fig. 7 A, B. REPORT ON THE CRINOIDEA. 41 primary interradials of Thaumatoerinus all end simply in a free rounded edge at the margin of the disk (Pl. LVI. figs. 1-3, 5), which is doubtless partly due to the simplicity of the arms. For these become free at once, and are not connected laterally by perisome, in which higher orders of radials could be supported. The interradial of the anal side, however, bears a small tapering appendage of four or five gradually decreasing joints, which terminates in a blunt point without any connection whatever with the anal tube near it (Pl. LVI. figs. 2, 4, 5). It appears to me to be of the same nature as the so-called proboscis of Taxocrinus, Gnormmocrinus, Onychocrinus, &e. The anal plates of these genera do not support a huge “ ventral sac,” such as occurs in the Cyathocrinide, but are of an altogether different nature. Good figures of them are given by Schultze,’ Angelin,’ and by Meek and Worthen.*? They may be advantageously compared with figs. 2 and 4-on Pl LYVI. According to Wachsmuth and Springer‘ the first anal plate of Tuaocrinus “ has a truncated upper side, and is succeeded by from two to six similar, narrow, quadrangular plates, longitudinally arranged. The plates diminish in size upwards, and form the dorsal side of a short and slender lateral proboscis, whose ventral parts, as well as the wall supporting them, have never been found preserved, and evidently consisted of more fragile material.” A few pages farther on they describe Onychocrinus as follows :—‘ In the anal area there is a series of from three to five very narrow, quadrangular plates, which rests upon the truncated or slightly excavated upper side of the basal, and forms a small lateral proboscis as in Taxocrinus. Interradials three to twenty, perhaps more in some species ; the first one large, resting between the first. and second radials, the succeeding ones smaller, rapidly decreasing in size and thickness upward, and having an inward curvature. They are followed by very minute irregular polygonal -plates, which form the interradial portion of the vault.” Meek and Worthen® described this anal series as resting upon the larger truncated basal, “ much as the arms of Platycrinus rest upon the first radials, and really looking very much like a diminutive arm rising from the anal area. This arm-like range of small pieces seems never to consist of more than from four to six or seven pieces, which are so small and narrow as to leave a wide open space between them and the posterior rays on each side.” Subsequently, however, they met with a specimen showing “ the space between the little arm-like range of anal pieces, and the radials and vault to be occupied by very numerous minute pieces.”® These last occur in each interradius, and are directly continuous with those forming the so-called “ vault ” or ventral disk, just in the same way as the perisomic plates between the rays of recent Crinoids (Pl. XIII. fig. 1; Pl. XXXIV. figs. 1,2; Pl. L. figs. 1, 2), of Hatracrinus, and 1 Monographie der Echinodermen des Eifler Kalkes, Denkschr. d. k. Akad. d. Wiss. Wien., Bd. xxvi., 1866, Taf. iv. figs, 2, 2b, 3, 4b. 2 Tconographia Crinoideorum, Stockholm, 1878, Tab. xvii. fig. 8; Tab. xx. figs. 9, 13, 16; Tab. xxiii. fig. 5. 3 Paleontology of Illinois, vol. v. pl. xiv. fig. 4. 4 Revision, part ii. p. 46, 5 Paleontology of Illinois, vol. ii. p. 243. 8 [bid., vol. iii. p. 494. (ZOOL. CHALL. EXP.—PART XXx1.—1884.) 6 42 THE VOYAGE OF H.M.S. CHALLENGER. of Apiocrinus, are continued upwards on to the surface of the disk between the ambulacra. Wachsmuth and Springer described this ventral disk of Onychocrinus and of other Ichthyocrinide as “ composed of a more or less soft or scaly integument, yielding to motion in the body and arms;”* and they regard it as homologous with the more solid vault of Platycrinus and Actinocrinus. I believe, however, as I shall explain more fully further on, that this was the real ventral surface of the Crinoid and not a “vault” at all; while the so-called proboscis or anal tube with the small interradials round it is just in the condition which the anal appendage of Thawmatocrinus would assume, did it exist in a larger Crinoid such as Pentacrinus asteria (Pl. XIII. fig: 1), with a well-plated perisome between the rays. This plating may be continued up on to the disk and to the summit of the anal tube (Pl. VI. fig. 42> PL eV fe 96 5 6PL SX VE. hess JET. fie 25 Pl XXXTX. fie, 25 Pls LY.), Tt unites the lower arm divisions closely together; and any additional appendage in the anal interradius would naturally be bound in with it, just as the four to seven joints of the anal appendage in Onychocrinus are bound in with the numerous minute pieces between the rays. But I see no reason for supposing that such an appendage would form part of the tube up to its opening, and be in any way grooved on its inner side. For it seems to taper away rapidly and to become merged into the general plating of the anal interradius in the flexible vault, or disk as I should call it. The passages quoted above both from Meek and Worthen, and from Wachsmuth and Springer, would admit of this interpretation ; and in the first case at any rate, it seems (from the context) to be the one which was intended. But Wachsmuth and Springer also speak of the anus of the Ichthyocrinide as “unknown except in Taxocrinus and Onychocrinus, which have a small lateral tube.”? This observation refers to the small appendage already mentioned; but it must not be understood to imply (as it well might) that this appendage is hollow and pierced by the rectum. Some older Crinoids, however, than Yaaxocrinus and Onychocrinus seem to have had an anal appendage like that of .Zhaumatocrinus, which was sometimes surrounded by numerous minute interradial pieces, so as to form a support to the anal side of the disk between the rays. I mean the genera Heterocrinus, Hall; Reteocrinus, Billings ; and Xenocrinus, Miller, all from the Lower Silurian of America.’ According to Wachsmuth and Springer’s definition of FReteocrinus, the posterior 1 Revision, part i. p. 31. * Revision, part i. p. 31. * As regards the second of these, I shall speak of it in the sense in which it is used by Wachsmuth and Springer, Wetherby, and others (Revision, partii. p. 191; Amer. Journ. Sci. and Arts, April 1883, p. 256). Ishould say, however, that 8S. A, Miller differs from his fellow-workers in America upon this subject, and refers the species grouped under Reteocrinus by Wachsmuth and Springer to, at least, three genera (Amer. Journ. Sci. and Arts, August 1883, p. 105 ; and Journ. Cine. Soc. Nat. Hist., vol. vi., December 1883, pp. 217-230). As, however, all the species referred by them to this genus appear to possess an anal appendage like that of Thaumatocrinus, Onychocrinus, and Tamocrinus, it is obviously more convenient to consider them all as congeneric, as I am also inclined to do for other reasons (see Phil. Trans., 1883, pp. 923-933). - REPORT ON THE CRINOIDEA. 43 interradial area is wider than the other four “with a conspicuous row of decidedly larger and more prominent pieces along the median part.” Billings’ gave a good figure of this in Reteocrinus stellaris, and spoke of it as follows :—“ If this series of joints constitute a true arm there must be six arms in this species.” Miller, who has examined the original specimen of Reteocrinus stelluris, describes it thus—“ Azygous interradial area covered by a large number of plates, probably one hundred or more, very unequal in size, the middle row being decidedly larger and more prominent than the others, so as to form a ridge up the middle. The plates in this row, however, do not rapidly diminish in size and fade out in their distinctive character before reaching the top of the vault; on the contrary, they are longer than the primary radials, four of them reach nearly as high as the secondary radials, and while the specimen is not preserved above this, enough is disclosed to the palzontologist to show that this series continued up the face of a proboscis that extended, may be as far, or farther, than the arms and the pinnules.” In default, however, of further evidence I prefer to believe that the middle row of plates in the anal area of Reteocrinus stellaris was of the same nature as, though perhaps on a larger scale than, that of Reteoerinus nealli, which Miller describes as follows :— “ Azygous interradial area covered by fifty or sixty plates, very unequal in size, the middle row being decidedly larger and more prominent than the others, so as to form a ridge up the middle, while the other smaller and less prominent ones are crowded in, irregularly, on each side. The plates in this middle row, however, have no uniformity in size or shape; the first one is large and elongated, the fourth is small and subquadrate ; and the row has become almost obsolete at the sixth plate, where all are nearly of the same size and scarcely distinguishable from the minute pieces which cover the flattened vault, and with which they unite.” The figures of this type in the Paleontology of Ohio (vol. i. pl. ii. figs. 3b, 3c) illustrate this description admirably, the original specimens having doubtless been seen by Miller; while the figure of Reteocrinus subglobosus on the same plate (fig. 2c) shows the incorporation into the body of a pinnule borne by one of the secondary radials. This pinnule is closely surrounded by the minute interradial plates, but may be distinguished from them at its origin just as the anal appendage is. This condition is still better shown in Reteocrinus richardson, Wetherby, which has two “fixed pinnules” in the anal interradius, one on either side of the median appendage. All three are “soldered” together by the minute irregular plates which pass insensibly upwards into those of the so-called “vault ;” and the ordinary pinnules on the lower parts of the arms after the last axillary are united in just the same way.” This condition recurs constantly in the Liassie Hatracrinus and in the recent 1 Decades of the Geological Survey of Canada, vol. iv. p. 64, pl. ix. fig. 4a. 2 Deseriptions of New Crinoids from the Cincinnati Group of the Lower Silurian and the Subcarboniferous of Kentucky, Journ. Cine. Soc. Nat. Hist., vol. ii. pl. xvi. figs. 1, la. 44 THE VOYAGE OF H.M.S. CHALLENGER. Pentacrinidz and Comatule ; and I see no reason to believe that the minute interradials of Reteocrinus are in any way different from those of the Neocrinoids. But I regard them as perisomic plates continuous with those of the disk above, which was in no sense a “vault” like that of the Actinocrinide. Meek’s figure of Reteocrinus nealli! illustrates this point admirably, and after examining disks like those of Pentacrinus wyville-thomsoni, Pentacrinus alternicirrus, Pentacrinus naresianus, and Pentacrinus mollis, together with similar disks in numerous Comatulee (Pl. XVIL fig. 6; Pl. XXVI. figs. 1, 2; Pl. XXX. fig. 2; Pl XXXIIT. fig. 7; PL LEV, fie. d0ic¢o Ph LV.) eamdaleo (thanks to the kindness of Mr. Wachsmuth) that of Reteocrinus nealli, I find it difficult to believe that the so-called vault of Reteocrinus was anything but the true oral surface of the animal. Miller's genus Xenocrinus’ is in this respect essentially similar to Reteocrinus. “The azygos area is remarkably large and covered in the central part by a vertical series of plates having about the same size as the regular radial series; and upon each side of the vertical series there is a depressed area covered by small plates having a tubercle in the central part, as in the regular interradial areas. There are seven plates, each having a length about twice as great as its width, in the vertical series, from the basal plate, upon which the series rests to the top of the vault. This vertical series is continued to the top of the proboscis, and contains in its entire length more than fourteen plates. It has such strong resemblance to the radial series, except as to the branching at the secondary radials, that the general appearance of the body is that of a species having six radial series.” Miller figures the specimen with fourteen plates in the vertical series, and remarks that we learn from it that “the proboscis extends as high as, and probably beyond the extremity of the arms.” He also says that the small plates between the rays and their subdivisions “ continue over the margin of the vault, and undoubtedly cover it, and also more or less of the long proboscis.” I do not see, however, that this so-called but unknown proboscis is anything more than an anal tube covered by perisomic plates, asin Letracrinus and so many other Neocrinoids. I also doubt whether Miller is right in stating that the vertical series is continued to the top of the proboscis, for (to judge from his figures) he does not seem ever to have met with a specimen perfect enough to show the top as it is shown in Meek’s figure of Reteocrinus nealli.® But I think it quite possible that, considering the size of this vertical series, it may have become free at the top of the calyx as the anal appendage of Thawmatocrinus does (Pl. LVI. figs. 4, 5), instead of tapering away quickly and ending on the lower part of the anal tube as in Reteocrinus nealli. The ventral sac or proboscis of Cyathocrinus is usually much larger and more 1 Paleontology of Ohio, vol. i. pl. ii. fig. 3c. * Description of some New and Remarkable Crinoids and other Fossils of the Hudson River Group, Journ. Cine. Soc. Nat. Hist., vol. iv. pp. 72, 78, pl. i. fig. 3; pl. iv. fig. 6. $ Paleontology of Ohio, vol. i, pl. ii. fig. 3c. REPORT ON THE CRINOIDEA. 45 complex in nature than that of Reteocrinus and Xenocrinus. But a transition between the two appears to be presented by some forms of Dendrocrinus, Heterocrinus, and Tocrinus. A little specimen figured by Meek, and referred to the aberrant type Dendrocrinus casei, shows the anal side very well.!_ Meek’s description runs as follows : — Anal series with the first piece resting directly upon the upper truncated side of the heptagonal posterior subradial (v.¢., basal) hexagonal in form, and bearing in direct succession above a series of hexagonal pieces gradually diminishing in size; while alternating with these similar small hexagonal pieces can be seen on each side of the mesial series, for some distance above the body between the free rays, and connecting with those of the ventral part.” His figure is a curious one, and does not quite agree with his description; for there seems to be a single large and pentagonal anal plate which separates two radials and rests in the angle formed by the upper edges of two basals (subradials, Meek). Upon this plate rests a series of seven gradually diminishing hexagonal pieces which stand out prominently from the smaller plates at their sides, just like the middle row of plates in the anal area of Reteocrinus nealli with which they seem to be comparable. If they supported a ventral sac like that of the typical Dendrocrinus, it was relatively much larger than that of Reteocrinus nealli, so that the vertical series of plates would end much farther from its summit than in that species. . Thus then in Onychocrinus, Taxocrinus, Reteocrinus, Xenocrinus, and even in Dendrocrinus casei the anal side shows this regular vertical series of plates which rests on a basal below and gradually diminishes in size. The only essential difference between it and the anal appendage of Thaumatocrinus is that it forms part of the body, being bound in with the rays by minute interradial plates which are not present in the simpler Thaumatocrinus. But this is often the fate of the lower pinnules in the Neocrinoids ; and it would assuredly also be the fate of an anal appendage in a Crinoid with the same calyx-characters as Thauwmatocrinus, but standing in the same relation to it as an extensively plated and multiradiate Comatula does to the naked and ten-armed Antedon rosaced. In the Cyathocrinoid genus Heterocrinus there appears to have been an anal append- age like that of Onychocrinus and Reteocrinus ; but it rested on the upper sloping sides of two adjacent radials instead of on a basal. In this type, as in the Cyathocrinidee generally, the capacity of the cup is compara- tively small, and the visceral cavity within the disk is almost entirely limited to its anal ce interradius, which is enormously enlarged, and forms the structure known as the “ ventral sac.” In Cyathocrinus itself this is a heavily plated tube, that commences at the upper edge of the “special anal” plate, above which its characteristic porous structure appears at once. But in Heterocrinus the ventral sac appears to be less robust, while the anal 1 Paleontology of Ohio, vol. i. pl. iii. bis. fig. 2c, p. 29. 46 THE VOYAGE OF H.M.S. CHALLENGER. series consists of ‘‘a single row of plates, longitudinally arranged, the outer side rounded and forming a prominent ridge, which gives the appearance of an arm.” * The physiological condition of this type appears to me to be very similar to that of Reteocrinus nealli, v.e., the anal interradius is supported by a special row of plates, the lowest of which are more or less incorporated into the calyx, while the upper ones are closely surrounded by perisomic plates. In Poteriocrinus and Ewpachycrinus this anal appendage is practically reduced to one plate, the so-called third anal plate, or the first plate of the ventral tube; but it rests on the first anal or azygous plate, which is itself supported by a basal. This azygous plate is absent in Ceriocrinus, and the first plate of the tube (anal appendage) comes down to rest directly upon a basal. Another curious modification is presented by Locrinus. The posterior side of the calyx is occupied by a large plate that rests between two basals and is in line with the radials. It has been variously described as a radial and as an azygous piece.? On its upper surface is a triangular plate which “supports on its right sloping side the usual number of brachials, and on the left a row of quadrangular plates, vertically arranged, | extending to the tips of the arms, and forming the posterior wall of a large ventral tube. In external appearance these plates resemble the brachials and arm plates, only they are somewhat higher and not quite as wide; they are gibbous and form an elevated ridge, which causes this appendage to resemble an arm or a branch of the ray.” This median ridge extends to the full length of the ventral sac, and it is bordered, just as is the case in Reteocrinus nealli, by a number of more delicate perisomic plates. I have little doubt that it served the same purpose in both cases, supporting the anal interradius, though in no way specially grooved for the reception of the hind gut. It is well figured by Meek in the Paleontology of Ohio, vol. i. pl. i. fig. 9D. 1 Revision, part i. p. 69. * For further information upon this subject, see Wachsmuth and Springer, Revision, part i. pp. 65, 71; and Amer. Journ. Sct. and Arts, vol. xxvi. 1883, pp. 370, 376; also P. H. Carpenter, Quart. Journ, Geol. Soc., vol. xxxviii., 1882, pp. 306, 307. REPORT ON THE CRINOIDEA. 47 IV.—THE RAYS. A. Tue Ray-privisions anp ARMS. The arms of a Neocrinoid, viewed in a strictly morphological aspect, must be regarded as commencing with the first joints beyond the primary radials. The same is the case in many Paleeocrinoids, of which Schultze says, “ Die Arme (brachia) beginnen unveriin- derlich da, wo eine deutliche Gelenkfacette eines festen Kelchstiickes ihren Ursprung ”* In the Platyerinidze and other Palzeocrinoids, and in all Neocrinoids (except- anzeigt. ing perhaps Guettardicrinus), this articular face is on the first radial. In the five-armed Eudiocrinus indivisus the next joints beyond the radials are syzygial, with pinnules on the epizygals,’ which clearly shows that they must be considered as arm-joints and not as belonging to the calyx, although they undoubtedly represent the so-called second and third radials of a ten-armed Crinoid. The other species of Hudiocrinus have these two primitively separate joints not united by syzygy but articulated, just as in Thawmatocrinus (Pl. LVI. figs. 1-4). The second one bears a pinnule both in Thawmatocrinus and in Eudiocrinus varians; but in Hudiocrinus semperi and Hudiocrinus gaponicus the first pinnule is on the fourth joint after the radial. This would correspond to the second brachial of a ten-armed Crinoid, but it is really the fourth brachial in Eudiocrinus. Lastly, in Perrier’s Kudiocrinus atlanticus * the first pinnule is on the fifth brachial, which corresponds to the third brachial of an Antedon. The well-known genus Rhizocrinus resembles Hudiocrinus indivisus in the syzygial union of the first two joints beyond the primary radials (Pl. X. figs. 1, 2, 6-8, 20). They have generally been called the second and third radials ; and there is some ground for this in the case of Rhizocrinus lofotensis, as they are considerably broader than all the joints which follow them except the first (Pl. LX. figs. 1,2). But in Rhizocrinus rawsoni (Pl. IX. fig. 3; Pl. LIII. fig. 7) they are not much larger than the four following joints, which contribute with them to support the visceral mass (Pl. X. fig. 20); while the first pinnule is on the last of these, 7.e., on the sixth joint above the calyx (PI. IX. fig. 3; Pl. X. fig. 20). Considering the evidence afforded by Hudiocrinus, I think, however, that it will be more consistent to describe Rhizocrinus as having only one radial; while the first pinnule would then be on the sixth (Rhizocrinus rawsoni) or on the eighth brachial (Rhizocrinus lofotensis). The terms second and third radials would then be used only in those cases where there are ten or more arms, owing to the third radials and more or fewer of the 1 Op. cit.,p.5. Seealso the genus Actinometra, Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. i. pp. 20-25, 1883 ; Zittel’s Palontologie, t. i. p. 339; de Loriol, Paléont. Frang. Terr. Jurass., t. xi. p. 15; Wachsmuth, Revision, part ii. pp. 9, 10. 2 Budiocrinus and Atelecrinus, Journ. Linn. Soc. (Zool.), vol. xvi. p. 495, 1882. 3 Sur des Eudiocrinus de Y Atlantique et sur la nature de la faune des grandes profondeurs, Comztes Rendus, t. xevi. No. 11, p. 726. 48 THE VOYAGE OF H.M.S. CHALLENGER. following joints being axillaries. This is in accordance with the nomenclature employed by Zittel, who speaks of the joint in Cupressocrinus, which is called “articulare” by Schultze, and ‘“‘second radial” by Roemer, as a “first brachial ;” while he only describes one series of radials in the five-armed Pisocrinus.* The developmental history of the plates also indicates elearly that the second and following radials are really arm-joints. For they commence as imperfect rings, which soon become filled up with lengthening fasciculated tissue, just as is the case with the stem-joints and later brachials. But the first radials, like the basals and orals, commence as expanded cribriform films; while the endogenous additions by which they are subsequently thickened are cribriform like those of the basals, and not fasciculated like those of the two outer radials and the following arm-joints. Messrs. Wachsmuth and Springer’ have been led by their study of the Paleocrinoids to the same conclusion, 7.e., that “the arms fundamentally commence with the second radials ;” although they find in practice that for purposes of description “ it is more convenient to regard the arms as commencing with the first free plate beyond the calyx.” In very many Neoerinoids with ten or more arms this would be the second radial ; and in the multiradiate Metacrinus (Pl. XXXVIII.; Pl. XLIII. fig. 2; Pl. XLVI.; Pls. XLVIII.—LIL.) this is actually a syzygial jomt with a pinnule on the epizygal just as in the simpler Hudiocrinus indivisus, but an axillary appears a few joints farther on, and the rays begin to divide. In the other Pentacrinidze, however, in Bathycrimus, Holopus, and in most Comatule, as well as in the fossil Hnerinus and Apiocrinide, the second joints above the primary radials are axillaries, and it is not till the second (or rarely the first) joints beyond these that pinnules appear. In all these types the axillary and the joint immediately below it are of the same width as the primary radials in the calyx. But in Marsupites and in many Paleocrinoids (Platyecrinus, Cyathocrinus, &c.) they are very-much smaller than the primary radials, just as the homologous joints are in Hyocrinus (Pl. VI.). The primary radials which form the upper part of the calyx are generally distin- guished as the first radials ; while the following joints, as far as the first axillary inclusive, are called the second, third radials, &c., though they are really only arm-joints as is shown by their bearing pinnules in Metacrinus (Pl. XII. figs. 6,8; Pl. XXXVIIL; Pl. XXXIX. Gos PLAKLU fig. 2) Pl XLV. figels PL XLVI ; Pl. GV fot Pie xe figs, 1,; 2\sP1. Ly figs..1, 8,10, 14,165 Pl U1. fig..1 ; (PL LIL digo), oisince, too; ibis very convenient for descriptive purposes to use different names for the different regions of the arms, I see no reason for altering the names by which these plates are generally known, provided that their real nature is not lost sight of. The conventional use of the term “radials” for the joints between the calyx and the 1 Paleontologie, pp. 348, 349. 2 Phil. Trans., 1865, p. 541, pl. xxvii. figs. 1, 3; Ibid., 1866, pp. 729, 742, pl. xli. fig. 1. 3 Revision, part ii. p. 10. —. | REPORT ON THE CRINOIDEA. 49 first axillary (inclusive) is particularly advisable in the case of the Neocrinoids. For among all the members of this sub-class which have ten or more arms,’ Metacrinus is the only genus besides Plicatoerinus in which the second joint beyond the primary radials is not an axillary, a character which has-elsewhere been pointed out as distinguishing the Neocrinoids from the Palzocrinoids.? In the various types of Comatulze and in some species of Pentacrinus there is a similar constancy in the number of joints which intervene between the successive axillaries of the dividing arms. I have therefore found it convenient ® to give special names to. the joints composing the primary and secondary arms respectively, and to restrict the term “brachials” to the joints composing those portions of the arms which undergo no further division. The joints of the primary arms may be called “ distichals,” a term no longer used with the precise meaning which Miiller attributed to it;* while the joints of the secondary arms (if there be any) may be termed “palmars.” These names are of much use in descriptions of Comatulz ; for in this family the number and character of the segments between the successive divisions of the arms exhibit variations which are, to a great extent, constant in different species, and thus give us the means of classifying them into larger or smaller groups.” The Pentacrinidze, however, exhibit a much greater irregularity in this respect ; and they also present more exceptions to the following rule, which holds good in almost all the Neocrinoids. The first two joints beyond every axillary of the dividing rays are united to one another in the same manner, either syzygy or bifascial articulation, as the second and third radials are. Thus, for example, there is a syzygy between the two outer radials of Encrinus, and another between the two lowest brachials. In Apioerinus and Millericrinus the corresponding joints are respectively united by bifascial articulations. This rule holds good in all the ten-armed Comatulx, whether the joints are articulated (Antedon rosacea) or united by syzygies (Actinometra solaris); and it is equally true in all the many-armed species with the exception of two groups of Actinometre, together with a few unusually aberrant types. In one group, which is represented by Actinometra multiradiata, the two outer radials and also the first two of the three distichals are articulated by ligaments only; but in all the subsequent arm divisions there is a muscular joint between the first two segments after each axillary, and the second one is traversed by a syzygy, whether it be itself an axillary or a free brachial, while the first bears a pinnule. Another variation occurs in Actinometra typica, Actinometra nove- guinee, and their allies. These forms have three distichals in the primary arms, the first two of which are articulated, while the axillary is a syzygy; but the two outer 1 This passage does not refer to Promachocrinus, in which genus there are ten primary rays. 2 On Allagecrinus, &e., Ann. and Mag. Nat. Hist., ser. 5, vol. vii., 1881, p. 296. 3 Actinometra, Trans. Linn. Soc. Lond., (Zool.), ser. 2, vol. ii. p. 24. + Bau des Pentacrinus, p. 31. 5 Classification of Comatule, Proc. Zool. Soc. Lond., December 1882, pp. 746, 747. (ZOOL. CHALL, EXP.—PaRT xxx11.—1884.) 7 50 THE VOYAGE OF H.M.S. CHALLENGER. radials are united by syzygy, as are the first two joints beyond the distichal and all subsequent axillaries. Exeept im these and a few other cases, however, there is a very great uniformity throughout the arm-divisions of the Comatule. In five of the eight recent species of Pentacrinus the two outer radials form a syzygy, and in correspondence with this the lowest distichals and brachials are similarly united in pairs (Pl. XII. figs. 18, 21; Pl. XV. figs. 1,2; Pl. XVI. fig. 1; Pl. XVIII. figs. 1-3, 8,11; Pl. XTX. figs, 1,16; 75 Pl. XXII. figs. 1d, 2d, 50; Pl. XXV.; PL XXVI figs. 4, 5, 8). On the other hand, the ten-armed Pentacrinus naresianus has a bifascial articulation between the two outer radials, and also between the two lowest brachials, just as in Antedon rosacea (Pl. XXX. figs. 1,11, 12, 16,17). But in Pentacrinus decorus and Pentacrinus blake: the rays divide twice or thrice; and though the two first joints beyond the lowest axillaries resemble the outer radials in being articulated by ligaments, yet there is a muscular joint between the two lower brachials of the ultimate arms, the second of which is usually a syzygy (Pl. XXXI. figs. 1, 2; Pl. XXXII. figs. 16-18; Pl. XXXIV. figs. 3,6; Pls. XXXV.-XXXVIL). The syzygial union of two arm-joints is of a somewhat peculiar character. For the hypozygal entirely loses its individuality as a separate segment of the arm, and bears no pinnule as the epizygal and the remaining brachials do (Pl. XII. fig. 9; Pl, XV. fig. 3; Pl XXX. figs. 1, 19, 20; 223) PL XXXa. figs. 10a,10b ita, 1b: Pl. XXXII. fig. 4; Pl. L. figs. 6-16). Thus, for example, in very nearly all Comatule the original third and fourth joints of the growing arm differ from those which ultimately appear beyond them. For ‘‘ whilst the majority of these gradually come to possess the true articulations, and to be separated by the intervention of muscles and ligaments, a certain small proportion become more intimately united on a simpler plan, which admits of no motion between them.”! The double or syzygial joimts thus formed resemble the ordinary brachials in bearing but one pinnule, and they are therefore best considered as single joints. In Antedon rosacea, for example, the third and fourth, the ninth and tenth, and the fourteenth and fifteenth joints of the growing arm are respectively united in pairs by syzygy ; but the arm is best described as having syzygies in the third, eighth, and twelfth joints. Soagain in the numerous Comatulz, such as Actinometra parvicirra, which have axillaries on some or all of the primary arms. Counted from the third radial, the distichal axillary is primitively the fourth jomt. The first, as is almost invariably the case, bears no pinnule, while the second has a pinnule, but the third not, for it is united to the following (axillary) joint by asyzygy. The first ray-division would therefore be described as consisting of three distichal joints, the second bearing a pinnule, and the third (axillary) a syzygy. The same arrangement occurs in the genus Metacrinus, which is distinguished from Pentacrinus and from all other Neocrinoids by having, not three radials only, but 1 Phil. Trans., 1866, p. 721. Serre fie, bie ‘e Hei » ‘ i¢ pt , + LG a eae he ‘ . : REPORT ON THE CRINOIDEA. 51 primitively five or eight. Two instances in which Pentacrinus varies in the direction of Metacrinus have come under my notice. One is in Pentacrinus miilleri (Pl. XV. fig. 2). The second and third radials are articulated, but the latter is an axillary with a syzygy, so that there are primitively four radials. In the other case (Pentacrinus decorus) there are seven primitive jomts in the ray. The first two above the primary radials are united by a bifascial articulation, while the axillary is a syzygy. I have elsewhere de- scribed two specimens of Millericrinus pratt: in which there are four radials, in one case on two out of the five rays (Quart. Journ. Geol. Soc., vol. xxxviii. p. 35, pl. i. fig. 23). Similar variations occur among the Comatule. In one Antedon that I have examined, one of the rays consists of five joints, the axillary being a syzygy ; while in individuals of two other species, the axillary rests directly upon its first radial, the second radial having remained undeveloped. When there are five radials in Metacrinus, as in Meta- crinus angulatus, the third and fourth bear pinnules; but the second does not, for it is united by syzygy to the third, and has lost its individuality as a separate joint (Pl. XII. figs. 5-10; Pl. XXXIX. fig. 1). The radials of Metacrinus angulatus, therefore, are practically four in number, the second of which is a syzygy and bears.a pinnule like the third. In Metacrinus nodosus, on the other hand, there are primitively eight radials, but besides the syzygy between the second and third, there is another between the sixth and seventh ; so that there are really only six joints, all of which except the first and last (axillary) bear pinnules, while the second and fourth have syzygies, and are as much single arm-joints as the third brachial or any other syzygial joint in the arm of Antedon rosacea (Pl. L. figs. 1, 6-16; Pl. LI. fig. 1). In Encrinus, Extracrinus, and in most recent species of Pentacrinus, as also in a few Comatulz (Actinometra solaris, Actinometra typica, &c.), the two outer radials and the first two joints beyond them are respectively united by syzygy. On the principle ex- plained above, each pair would therefore be considered as forming a single joint, so that the true third brachial (itself a syzygial pair) would come to be the second. This would involve our describing these forms as having but two radials, the axillary with a syzygy, and syzygies both in the first and in the second brachials. I think, however, that this would be misleading, and make the difference between this type and that of Antedon rosacea and Pentacrinus naresianus appear much greater than it really is. The presence of three radials is such an absolutely constant character in all the five- rayed Neocrinoids excepting Metacrinus and Plicatocrinus,' that the fact of the outer ones being united by syzygy and not articulated seems to me to be of minor importance; and I do not assign to it the same morphological value as the syzygial union of the third and fourth primitive brachials, in which the former loses its pinnule. No Crinoid with 1 Zittel has described a six-rayed example of this genus, in which the first joint above the cup (called by him the first brachial) is axillary as in many Palocrinoids (Sitzwngsb. d. IL. Ol. k. baier. Akad. d. Wiss., 1882, Bd. i. p. 105). 52 THE VOYAGE OF H.M.S. CHALLENGER. three radials ever has a pinnule on the second one; and when this becomes the hypozygal of a syzygy, it does not therefore lose its individuality, as is the case with the hypozygals of the ordinary brachial syzygies. Almost the same may be said respecting the first two brachials. Most Comatulee, like Pentacrinus naresianus (Pl. XXXa. figs. 1, 10a, 10), 12a, 12b), have a syzygy in the third brachial with a bifascial articulation between the two preceding joints, of which only the second bears a pinnule. Hence, when these two are united by syzygy, as in Actinometra solaris, Actinometra typica, &c., the lowest or hypozygal loses no individuality as an arm-joint. They are, therefore, better described as the first and second brachials, and not as a first brachial which “is a syzygy.” This method has the advantage of retaining the third brachial as a syzygial joint as a condition which is common to by far the larger number of Comatule. For it is only in a very few species like Actinoietra fimbriata and Actinometra multiradiata that there is a syzygy in the second brachial and a pinnule on the first, as is often the case in Metacrinus. This is an entirely different type, and arises from the coalescence of the primitive second and third joints of the growing arm. Syzygial unions of two primitively separate arm-joints occur with great regularity throughout the arms of the Comatule. In the two principal genera Antedon and Actinometra, there are large groups of species typified by Antedon eschrichti and Actinometra parvicirra respectively, in which syzygies occur at tolerably regular inter- vals of three joints. It is rare, however, to find a perfectly regular arm, especially in the latter species, in which the “syzygial interval” may vary from 0 to 10 joints.!. In other species the interval may be as much as twenty joints or more; while it is occasion- ally two, as in Antedon rosacea, and in rare cases one joint only, as in Rhizocrinus. But it is generally possible to find a considerable amount of regularity in the number of joints which form the syzygial interval in any given species, and this is often of some value for systematic purposes. Among the Pentacrinide, however, this is only the case to a very slight extent. The syzygial interval is perhaps most regular in Pentacrinus naresianus (Pl. XXVIIL); but it is long as in many tropical Comatulz, and in other Pentacrinide the brachial syzygies are usually “ few and far between.” In Rluzocrinus and Hyocrinus, on the other hand, the syzygial union of the primitive brachials is carried on to a very great extent. In the former genus syzygial and muscular unions alternate with one another continuously from the calyx to the arm-ends (Pl. IX.; Pl. X. fig. 20; Pl. LIII. fig. 7). In Hyocrinus (Pl. VI. figs. 1, 2), as was well described by Sir Wyville Thomson,” the five arms “ consist of long cylindrical joints deeply grooved within, and intersected by syzygial junctions. The first three joints in each arm consist each of two parts separated by a syzygy; the third joint bears at its distal end an articulating facet from which a pinnule springs. The fourth arm-joint is intersected by 1 Actinometra, loc. cit., p. 49. 2 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p, 52. i 7 REPORT ON THE CRINOIDEA. D9 two syzygies, and thus consists of three parts, and so do all the succeeding joints; and each joint gives off a pinnule from its distal end, the pinnules arising from either side of the arm alternately.” In this type, therefore, two-thirds of the arm-joints lose their individuality altogether. They bear no pinnules and take no part in the movements of the arms. In Rhizocrinus half the brachials are in the same condition; while more than half are devoid of pinnules, as the lowest pinnule-bearing joint is the sixth or sometimes even the eighth primitive brachial (PI. [X.). It is worth notice that the modes of arrangement of the arm-joints which are characteristic of Hyocrinus and Rhizocrinus respectively, are precisely paralleled by the condition of certain species of the Paleozoic Heterocrinus. Thus in Heterocrinus con- strictus, Hall, the pimnules are borne alternately on opposite sides of the arm by every third joint ; and I have little doubt, from the figures of the arms which are given both by Hall” and by Meek,’ that each group of three joints is intersected by two syzygies just as in Hyocrinus (Pl. VI. fig. 1). On the other hand, the alternation of syzygies and muscular joints, which is so characteristic of Rhizocrinus, also occurs in Heterocrinus simplex ; and Meek’s figures * show that the opposed syzygial surfaces were striated as in Apiocrinus and Comatula, and not plain as in Pentacrinus and Rhizocrinus. It has been pointed out already * that the supposed syzygies in the arms of Bathy- crmus (Pl. VIL. fig. 2; Pl VIIL figs. 1, 2; Pl. VIIa. fig. 1) are really articulations of a peculiar type, though the fossze and vertical ridge are barely visible in the outer parts of the arms, and would probably have escaped notice altogether, but for the very marked differences from ordinary syzygial surfaces which are presented by the apposed faces of the two outer radials, or of two of the paired lower brachials (Pl. VIIa. figs. 16, 19, 20, 22). Nevertheless, the proximal joint of a pair so united resembles the hypozygal of a syzygy in the non-development of its pinnule ; and it might therefore be urged that every pair so united should be properly considered as a single joint, just as in the case of a syzygial pair which only bears a pinnule on the epizygal. It must be remembered, however, that the syzygial union is an immovable one, which is far from being the case with any arti- culation, whether bifascial or trifascial; and the reasons given above for retaining the individuality of the two outer radials and of the first two joints beyond any axillary, even when they are united by syzygy, apply equally well in the case of Bathycrinus. For the hypozygal joints of syzygial pairs are not the only ones which never bear pinnules. The lower joint of every pair forming a bifascial articulation is distinguished in the same way, e.g., the first joints of the various arm-divisions in most Comatulz, and the first brachials of Pentacrinus naresianus (Pl. XXXa. fig. 12b). The same is also true in the many- armed Pentacrinide, when there are many joints in an arm-division and the axillary is 1 Twenty-fourth Annual Report on the New York State Museum of Natural History, Albany, 1872, pl. v. figs. 13, 14. * Paleontology of Ohio, vol. i. pl. i. fig. 10. 3 Ibid., pl. i. fig. 7. 4 Anie, pp. 8, 9. 54 ‘ THE VOYAGE OF H.M.S. CHALLENGER. united to the preceding joint by a bifascial articulation instead of by syzygy. In fact it is a general rule in all Crinoids that pinnules are only borne by those joints which are united to their successors by paired muscular bundles. The hypozygal in the brachial syzygies may be fairly considered as losing its indi- viduality. Not only does it bear no pinnule, but it takes no part in the movements of the arm. But when two joints are united by ligamentous bundles on either side of a vertical ridge, they are able to share in the lateral movements of the arm, though not in those of flexion and extension ; and it therefore seems unreasonable to consider a pair so united as equivalent to one joint only. Sir Wyville Thomson was accustomed to regard the stem and its appendages as constituting the “vegetative system” of the Crinoid, as distinguished from the more strictly animal portions, viz., the cup and arms. In describing Rhizocrinus for example,’ he specially alluded to the great ‘“ preponderance in bulk of the vegetative over the more specially animal parts of the organism ;” and he subsequently pointed out that in Hyocrinus and Bathycrinus,? as in Rhizocrinus, there is ‘a comparatively excessive development of the vegetative system.” This was generally the case throughout the Bourgueticrinidee and Apiocrinide, none of which have any very great number of arm- joints, though the “body” may be considerably enlarged with the help of the upper part of the stem. Thus, for example, d’Orbigny’® describes two twenty-armed species of Millericrinus, each reaching a total length of one metre, out of which the calyx and arms together only take up 86 and 94 millimetres respectively, less than one-tenth of the whole; while in one ten-armed species the calyx and arms together only measure 29 out of 920 millimetres. Among the Palocrinoids there is considerable variation in the relative development of the stem as compared with the body and arms. The latter are often absent altogether, as in the Blastoids* and many Cystids; while they are few in number and poorly developed in Haplocrinus, Pisocrinus, Symbathocrinus, &e. On the other hand, the body and arms, so enormously developed in Crotalocrinus, are quite extensive in many Cyathocrinide and Actinocrinide ; but the stem is often large and complicated at the same time, as in Barycrinus and Megistocrinus.’ In the Liassic Extracrinidee the stem, immensely developed as it may be, still falls considerably short of the body and arms in the complication of its structure. Extracrinus briareus has a comparatively short stem; but in Extracrinus subangularis it may exceed 50 or even 70 feet,° with but few cirri except near the calyx, and those 1 “Porcupine” Crinoids, Proc. Roy. Soc. Edin., vol. vii. p. 771. 2 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p. 48. 3 Hist. Nat. des Crinoides, pp. 39, 41, 44. 4 The so-called “pinnules” of the Blastoids cannot be properly compared to those of the Crinoids, for they do not seem to have contained the genital glands. 5 Revision of the Palzocrinoidea, vol. i. pp. 14, 15. § Eneriniden, pp. 271, 291. REPORT ON THE CRINOIDEA. 55 only small ones. The arms, however, reach an enormous development, and Quenstedt calculates the total “ Krone” to contain not less than five million pieces.’ In the recent Pentacrinidze the arms are generally well developed in proportion to the stem. This proportion is of course least in young individuals, as shown in Pls. XXXV. and LI., while it is greatest in forms like Pentacrinus miilleri, Pentacrinus maclearanus, Pentacrinus wyville-thomsoni, and Pentacrinus alternicirrus (Pls. XIV., XVI., XIX., XXV.). These lead a semi-free existence, owing to the fracture of the stem at a node, as was probably also the case in Eutracrinus briareus with its large “Krone? Among the Comatulide the vegetative system is reduced to a minimum, as they have no stem in the adult condition. The arms, however, are often very extensively developed, far more so than in any recent Pentacrinide. The ultimate arms of a Pentacrinus or Metacrinus do not often exceed forty in number; and they rarely consist of more than one hundred joints, though twenty or thirty more may intervene between the last axillary and the calyx (Pls. XIV., XVI; Pl. XVIII. fig. 1; Pl. XIX. fig. 1; Pl. XXV.; PL XMVIUL. figs Us) Pl) XXX. fig.1; Pl. XXXIV. fig. 1; Pls. XXXVML,'XIk, XUIL- Bie fee Ele SUING fies? » PL XLV. figs U2 Pls, XVI, KEVIN: PL XLS fig. 1; Pl. LIT. fig. 1). On the other hand, although there are quantities of ten-armed Comatule, very many species, especially of Actinometra, have from forty to sixty arms; some, like Actinometra bennetti, and Actinometra schlegeli, eighty or more; and in a few gigantic types like Actinometra nobilis’ there may be over one hundred arms. Further, the number of arm-joints is generally from one hundred and twenty to one hundred and fifty, apart from the syzygies ; while in a large Antedon eschrichti or Actinometra bennetti and in other multiradiate species of the latter genus there may be over two hundred arm-joints. Nearly all of them bear pinnules, which are often very long until quite near the arm ends. But in Metacrinus and also in Pentacrinus, though to a considerably less extent, the development of pinnules stops short some little way from the extremity of the arm ; and its outermost segments bear little stumps of two or three joints only, or may even show no signs of pinnules at all (Pls. XXV., XXVIII, XXXI., XXXIV., XXXVIIL, XL., XLIL; Pl. XLII. fig. 4; Pls. XLIV., XLVI., XLVIIL, XLIX., LL, LIL). The same peculiarity is repeated on a smaller scale in the ambulacral plates of the pinnules. Those of Comatule (when present) are continued almost to the end of the pinnule (Pl. LIV. fig. 6). But in the Pentacrinide the last few pinnule joints, some- times even four or six, are totally devoid of any ambulacral plating (Pl. XV. figs. 7-9; RES Siete ehh Xl hey 9) PE XLVIL fig, 10; Pl) XLIX: fig. 7; Pl Ep fig. 5). The same is the case with the extremities of the arms. In fact, both in the persistence of the stalk and of the external basals, and also in the nature of the arms, 1 Encriniden, p. 292. * The specific formula of this type is—a.3. 5 .3.3. ; : 56 THE VOYAGE OF H.M.S. CHALLENGER. the Pentacrinidee show very clearly that they are rightly regarded as permanent larval forms of the Comatulee. Rhizocrinus and Bathycrinus, with their relatively large vegetative system, manifest the same character in another way, viz., the absence of pinnules from the arm-bases; though the ambulacral plating is continued to the end of both arms and pinnules (EVIL fas: 2.75 Pl. VIlEsiee ies. SeePe VUla. fig. 1). There is good reason to believe that the late appearance of the basal pinnules (excepting on the second brachial) is a marked developmental character among the Comatule;* and in one genus, Aftele- erinus, the first pinnule is as far out as the twelfth brachial, the lower pinnules not developing at all. In Rhizocrinus rawsoni it is on the epizygal of the third syzygial pair, or the sixth primitive joint, and in Rhizocrinus lofotensis on the epizygal of the fourth pair (PI. IX. figs. 1-3); while in Bathycrinus it may be as many as eleven joints from the radial axillary, though occasionally only eight or nine (Pl. VIIL. figs. 1, 3). Tn all the genera of living Crinoids, with one singular exception, the mouth is situated at or near the centre of the disk (Pl. III. fig. 2; Pl. VI. fig. 4; Pl. VII. fig. 3; Pl. XVII. figs. 6,10; Pl. XXVI. figs. 1,2; Pl. XXXIV. fig. 2; Pl. XXXIX. fig. 2; Pl. LV. figs. 3-7 ; Pl. LVI. fig. 6), and the arms are about equally developed on all the five rays. But in the large Comatulid genus Actinometra the mouth is excentric or even marginal (Pl. LV. figs. 1, 2; Pl. LVI. figs. 7,8); and there is frequently a considerable amount of difference in the development of the oral or anterior, and the aboral or posterior arms. Even when all the arms are provided with food-grooves on the ventral surface as in other Crinoids, those which come off round the mouth are usually longer, sometimes considerably so, than those which spring from the hinder part of the disk; while in other species the anterior and posterior arms are all grooved and all equal in length, but the distribution of their syzygies is quite different. A great many species of Actinometra, however, are characterised by a still more striking difference between the anterior and posterior arms. The former have a wide food-groove of the usual character and a well-developed tentacular apparatus at its sides, while they always appear to end in a “ growing point.” The posterior arms, on the other hand, have an ungrooved and convex ventral surface, which is without any respiratory tentacles at all (Pl. LVI. fig. 7). They are only about half the length of the grooved anterior arms, and, therefore, taper much more rapidly, while they terminate in an axillary segment which bears two pinnules of the ordinary character. The genital glands which they contain are usually far more developed than those of the anterior arms. Not only are there more fertile pinnules, though the total number of pimnules may not be much more than half that of an anterior arm; but the portions of the glands within these pinnules also attain a greater size than in the oral arms, the basal and median pinnules of the latter being usually less swollen than the corresponding pinnules of a posterior arm. 1 Preliminary Report on the Comatule of the Caribbean Sea, Bull. Mus. Comp. Zoél., vol. ix., No. 4, pp. 14, 15. i REPORT ON THE CRINOIDEA. 57 A similar inequality in the development of the genital glands has been noticed by Prof. A. Agassiz as occurring in the Echini.* This frequent difference in length between the anterior and the posterior arms of Actinometra, accompanied by the difference in the character of their terminal pinnules, seems to be to some extent dependent upon the condition of the respiratory apparatus occupying their ventral surface. When this is well developed the arm seems to have the power of indefinite growth. For in a great many individuals of various species which have all the arms grooved and tentaculate like those of Antedon, there is no very appreciable variation in their length or m the development of their genital glands. There appears to be no rule of any kind respecting the condition of the arms in any given species of Actinometra. In the case of Actinometra parvicirra, for example, I have seen individuals with thirty-three arms, all of which were grooved and tentaculate ; while in another with thirty-one arms as many as nineteen were grooveless and unprovided with tentacles. All sorts of gradations between these two extremes will be found in any large collection of Actinometre.’ Half the species of this genus which were dredged by the Challenger have more or fewer ungrooved and less developed arms. They may occasionally be found upon the anterior rays; while in Actinometra nobilis and Actinometra magnifica,’ which have one hundred arms or more, several of those on each ray are short and less developed, with neither food-groove nor tentacles on their ventral surface (Pl. LVI. fig. 7). Even in the normal grooved arms of Actinometra the lower pinnules are frequently erooveless and non-tentaculate, just as the hinder arms may be (Pl. LXI. fig. 3). Some- times only three or four, sometimes as many as forty, are in this condition, bemg more or less swollen by the development of the genital glands within them; but they do not receive any branches from the brachial ambulacrum, which is itself often but imperfectly developed (see woodcut, fig. 4, p. 113). This ungrooved condition of the lower pinnules may also occur on all the arms of some species of Antedon ; and it is especially remarkable in types like Antedon acala and Antedon angusticalyx,* which have a strongly plated ventral perisome. The ambulacral grooves of all the arms and of the later pinnules are well protected by plates (Pl. LIV. figs. 4, 7, 8, 9); but they do not extend on to (about) the first twenty pinnules which contain the large genital glands, though the latter are protected by a very close and regular pavement of anambulacral plates (PI. LIV. figs. 1-8, 5). In other species, however, which have equally plated pinnules, such as Antedon incerta, the ambulacra extend over their ventral surface in the usual way (Pl. LIV. fig. 6). 1 Revision of the Echini, part iv. pp. 680, 681. 2 Actinometra, loc. cit., pp. 31-41. 3 The specific formula of this type is—a.3.2.3.3. = : 4 The following are the specific formule of these types: Antedon acela,—A .10. a Antedon angusticalyx,—A . 3. - : ® The specific formula of Antedon incerta is—A . 10. < ; hs (ZOOL. CHALL, EXP,—PART xxxI.—1884.) 53 THE VOYAGE OF H.M.S. CHALLENGER. B. Tae PINNULEs. The pinnules are repetitions of the arms on asmall scale, and are especially adapted for the protection of the genital glands (PI. Ve. figs. 7, 8,10, ¢; Pl. VII. fig.7; Pl. X. fig. 20). In no ease is a pinnule developed earlier than the second joint above the first radials of the calyx. This condition occurs in the two five-armed genera Thawmatocrinus (Pl. LVI. figs. 1, 2) and Eudioerinus. One species of the latter (Hudiocrinus varians) has this second brachial free and capable of lateral movement, while im another (Ludiocrinus indivisus) it is the epizygal of a syzygy. The corresponding radial joint of Metacrinus is of the same character, and there are pinnules on each of the following radials as far as the axillary (Pl. XXXVIIL; Pl. XXXIX. fig. 1; Pl XLIL; Pl. XLII fier kl SUuEW.s (Pi, kV, oat PL VIL PY ek VEE ines ole Lee ke tess Pls. L.—LII. fig. 1). But in the majority of Neocrinoids which have the third radial an axillary, the preceding joint bears no pinnule, while it sometimes contributes to the enlargement of the cup. Pinnules are always absent from every axillary joint, from the hypozygal of every syzygy (Pl. XXXa. fig. 106; Pl. XXXII. figs. 4, 6, 13, 14; Pl. L. figs. 11, 12), and also from the lower one of every pair of joints which are united by a ligamentous articu- lation; so that in the great majority of Comatule, as in some species of Pentacrinus, the first joint after each axillary bears no pinnule. In the former group too the pinnules on the third and the four or five following brachials which form the arm-bases, do not appear till after those of the eighth and following joints, though the pinnule of the second brachial is developed comparatively early ; while in Atelecrinus, Rhizocrinus, and Bathycrinus more or fewer of the lowest brachials are permanently devoid of pinnules. The lowest pinnules of the Comatule, and in a less degree those of the Pentacrinidze also, usually differ somewhat from their successors; and they may present a variety of characters, which are of considerable value in the discrimination of species, owing to the comparative constancy of their occurrence. They are frequently distinguished by the presence of spurs or keels upon their basal joints, as in Actinometra solaris; or they may be long, slender, flexible, and flagelliform, as in Antedon rosacea; or they may be stiff, straight, and spine-like, as in Antedon protecta; or they may have large prismatic basal joints, as in Metacrinus (Pl. XXXVIIL; Pl. XXXIX. fig: 1; Pl. XLIIT. figs. 2, 4 ; PL SEI. “fie, 2;PE XLVI: Pl XIX. fies, 15/2 PE os ear ey eA siren or the dorsal surfaces of their joints may have forward projecting keels, as in Pentacrinus asterius (Pl. XIII. figs. 1, 14). Dr. Carpenter’ has observed that the first pinnules of the ten-armed Antedon rosacea, which habitually arch over the disk and are much longer than their successors, are 1 On the Structure, Physiology, and Development of Antedon (Comatula) rosaceus, Proc. Roy. Soc., vol. xxiv., 1876, p. 226. REPORT ON THE CRINOIDEA. 59 extremely susceptible of irritation. When they are touched in the living animal, the whole circlet of arms is suddenly and simultaneously coiled up over the disk ; while irritation of one of the ordinary pinnules is simply followed by the flexion of the arm which bears it. The structure of these “oral pinnules,” which in Antedon rosacea and allied species are borne by the second brachials, differs very considerably from that of the pinnules on the other arm-joints. For not only are they sterile, but they have neither tentacular apparatus nor ambulacral groove. Their ventral surface is slightly convex, instead of being concave, as in the ordinary arms and pinnules; while the ciliated ambulacral epithelium, together with the subjacent nerve and radial blood-vessel, are also absent. This.appears to be the case with the oral pinnules of almost all Comatulze ; while in some species of Actinometra whole arms, with all the pinnules which they bear, are in the same condition. In the Pentacrinid, however, the lowest pinnules of the rays are usually all grooved like their successors, and not devoid of the ambulacra with all their accessory structures, as in the Comatule (Pl. XXXIV. fig. 2). In fact the pinnule-ambulacra of Metacrinus often start directly from the peristome or from the five primary groove-trunks of the disk, instead of from the particular branches corresponding to the arms which bear the pinnules (Pl. XX XIX. fig. 2; Pl. XLII. fig. 3; Pl. L. fig. 2). The fact that the pinnules are only arms in miniature is very well shown by the process of their development at the terminal growing points of the young arms. The first indication of a pinnule is the formation of a fork at the growing point, the two limbs of which are at first almost equal (Pl. XXXV. fig. 1). “One of these rami, however, grows faster than the other, and soon takes a line continuous with that of the axis of the arm, from which the other diverges at an acute angle, so that the former comes to be the proper extension of the arm, while the latter soon takes on the characters of a pinnule. Ere long, however, the growing point of the arm again subdivides ; two branches are formed as previously ; and whilst one of these becomes a continuation of the arm, the other is soon to be distinguished as-a pinnule given off from it on the side opposite to that of the first formed pinnule.” ? In all the Neocrinoidea, with the exception of Hyocrinus, the pinnule borne by any joint is small in comparison with the arm of which that joint is a part. But in this aberrant genus (PI. VL. figs. 1, 2) the pinnule-bearing joints have rather the appearance of axillaries. For the pinnules are large in proportion to the arms, and are nearly equal in length to the parts of the arms which are beyond the joints where they originate, so that the outer ends of all the pinnules, as well as those of the arms, meet nearly on a level. Hence the pinnules of Hyocrinus have some resemblance to the “armlets” or small and undivided but pinnule-bearing arms which come off from the inner faces of the axillaries of Extracrinus. But their function as pinnules is shown by the way in which they are 1 Phil. Trans., 1866, p. 734. See also Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. ii., 1877, p. 40, pl. ii. figs. 4, 6. 60 THE VOYAGE OF H.M.S. CHALLENGER. enlarged to receive the fertile portions of the genital glands, no part of these appearing in the arms (Pl. Ve. figs. 7, 8, 10, ¢; Pl. VI. fig. 1); while they have no appendages of their own as the armlets have in Extracrinus. The peculiar pinnule arrangement of Hyocrinus helps us to understand why there are no pinnules upon the axillaries of multiradiate Crinoids. These may be considered as ordinary pinnule-bearing joints, so modified that the pinnule and the continuation of the arm which bears it are equal in size or nearly so. As mentioned above, this is in fact the mode of formation of the pinnules at the growing points of the arms, as is well shown in a very young individual of Pentacrinus decorus (Pl. XXXYV. fig. 1). The joint which bears the last formed pinnule is an axillary with two nearly equal distal faces; and the pinnule can only be distinguished from the continuation of the arm by the greater length of its component joimts. Furthermore, in the short posterior arms of Actinometra, the only ones in which the normal mode of termination has been observed,’ the last joint is an axillary which bears two pinnules of the ordinary character. In Rhizocrinus (Pl. IX. figs. 4, 5) as in Hyocrinus (Pl. VI. figs. 1, 2) the pinnule- bearing joints have very much the appearance of axillaries with unequal distal faces; and a similar inequality is shown by the axillaries of Hatracrinus, each of which bears an “armlet” on one face and the continuation of the main arm-trunk on the other. Numerous instances of reparation after injury also indicate the close similarity of arms and pinnules. A very common one, sometimes to be met with in Antedon rosacea, is as follows :—The epizygal of the third brachial is broken away, carrying with it all the outer part of the arm, as well as the pinnule which it bears. But it is replaced by an axillary with two distal faces, from each of which an arm eventually grows out, one or other of them perhaps dividing again, as in the specimen of Pentacrinus decorus shown on Pl. XXXVI. On the other hand, in an abnormal individual of Metacrinus angulatus, the eighth distichal is not an axillary, as is usually the case. But it is somewhat swollen and has a slightly larger pinnule than the preceding joint, so that it resembles an axillary with unequal faces. In the specimen of Actinometra strota which is represented on Pl. LV. fig. 2, one of the second brachials of the right posterior ray bears two fully developed pinnules instead of an arm and its own proper pinnule, so that it looks like an axillary. There is no disk-ambulacrum corresponding to this undeveloped arm. Considering therefore the fundamental identity of arms and pinnules, one would scarcely expect that an axillary joint which gives rise to two arms (often unequal in size) should bear a pinnule as well (see pp. 347, 358). The pinnule arrangement of Hyocrinus is totally unlike that of any other Neocrinoid, although, according to Sir Wyville Thomson,’ we have something very close to it in some species of the Paleozoic genera Poteriocrinus and Cyathocrinus. These names were probably employed by Sir Wyville in the wide sense, and not with the restricted meaning Actinometra, loc. cit., p. 40, pl. ii. fig. 6, 2 Journ. Linn. Soc. Lond. (Zool.), vol. xiii., 1876, p. 52. REPORT ON THE CRINOIDEA. 61 which they now possess. - There are no true pinnules in Cyathocrinus proper, but only repeatedly branching arms, which must therefore have contained the genital glands; and each of the branches borne by one of the lower axillaries may fork again several times, so that they cannot be compared to the long, undivided pinnules of Hyocrinus (Pl. VL. figs. 1, 2). In Poterioerinus, on the other hand, the successive arm-joints bear pinnules which are not specially different from those of Neocrinoids ; while the mode of branching of the arms resembles that characteristic of Pentacrinus miilleri, and more especially of Extracrinus, the axillaries being generally limited to the outer arms of the ray, and having unequal distal faces." It is in the curious genus Barycrinus, which was separated from Cyathocrinus by Mr. Wachsmuth, that we find the nearest approach to the pinnule-arrangement of /Tyocrinus. According to Wachsmuth and Springer” “all the main arms, instead of bifureating, give off at regular intervals, alternately on opposite sides, and from the inner margins of the plates, short, rounded, simple armlets, which in most species throw off secondary branches as in Botryocrinus, and these armlets here as there, probably performed the office of pinnule.” Barycrinus hoveyi, var herculeus, M. and W., is one of the excep- tional species in which the armlets are simple and without secondary branches. The excellent figure of it which is given by Meek and Worthen® shows these armlets to come off alternately on opposite sides just as in Hyocrinus, but from every second joint, instead of from every third (Pl. VI. figs. 1, 2). They have unfortunately never been found in a perfect condition; and we cannot tell therefore whether they reached to the level of the top of the arms proper as in Hyocrinus, though Meek and Worthen’s description seems to indicate that such is the case. The difference between these armlets of Barycrinus herculeus and those of Hxtra- erinus is that the former seem to bear no pinnules as the latter do, and must therefore have contained the genital glands ; while they come off alternately from opposite sides of the main arm-tfunk, and not from its inner one only as in Hxtracrinus. We have seen that the pinnule of a Neocrinoid is practically a reduced copy of an arm, but modified by the great development of the fertile portion of the genital gland which it contains, that part of the gland which is confined to the arm being usually sterile and known as the “ genital cord” or “rachis” (Pl. Ve. fig. 1; Pl. VIIla. figs. 4, 5; Pl. LX. fig. 6—ge.). Although it would seem improbable that the pinnules of Palzocrinoids are essentially different in nature from those of the Neocrinoids, Messrs. Wachsmuth and Springer have attempted to show that the small alternating plates covering the brachial ambu- lacra of Cyathocrinus are homologous with the pimnules of the Actinocrinide and Platycrinide. These are long, comparatively slender, and closely arranged side by side 1 See p. 277. 2 Revision, part i. p. 103. 3 Paleontology of Illinois, vol. v. pl. xiii. fig. 2. 62 THE VOYAGE OF H.M.8. CHALLENGER. = just as on the feathery arms of Antedon eschrichti and hosts of other Comatule ; and they are obviously of the same nature as the pinnules of Neocrinoids generally. “‘ When the arms are closed, the two series of pinnulz of one arm are laid upon each other so neatly, that the arm-furrow must have been thereby perfectly shut off from the surround- ing water. No additional covering has yet been observed in these genera, and it was evidently unnecessary. All this seems to point to the conclusion that the pinnule had the same functions, partly at least, as the alternate plates in Cyathocrinus, &c., and as both have the same position, and evidently could be opened and closed by the animal, we do not hesitate to consider the latter as the homologue of the former, or in fact as rudimentary pinnulz.”* The first sentence of the above passage concerning the pinnules of Actinocrinus and Platycrinus would apply equally well to any Comatula or Pentacrinus, whether the ambulacra be plated or not (Pl. XIII. fig. 13; Pl. XIV.; Pl. XVII fig. 1; Pl. XXVII. Hes 5 Pl IT, fie. 33) Pleo Mil feo dds Ply VL, fete Aa atte, a) 3 As regards the last paragraph, 1 cannot help thinking that it affords an instance in which analogy has been mistaken for homology. The overlapping of the pinnules so as to cover in the ambulacra may occur in all recent Crinoids; while the grooves of the pinnules themselves, like those of the arms and disk, are often bordered by two more or less distinct rows of minute movable alternating plates, the “covering plates.” These may themselves be supported on “side plates,” thus making four rows in all, which are sometimes very fully developed as in Hyocrinus, together with many Pentacrinidee and Comatulee (Pl. Ve. figs. 9, 10; Pl. VIlla. fig. 5—cp. Pl. XIIL figs. 15,16; Pl. XVII. fig. 8; Pl. XXVII figs. 4-6, 11-13; Pl. XXXIII. figs. 1-4; Pl. XLI. figs. 4, 11-13; Pl. XLVII. figs. 10-12; Pl. XLIX. figs. 6, 7; Pl. LI. figs. 11,12; Pl. LIL figs. 5,6; Pl. LIV. figs. 4, 6-9). Similar plates occur on the pinnules of Actinocrinidee and Platycrinidee, their grooves being “ covered by a double series of very minute pieces, though, owing to defective preservation, this covering is rarely observed.” These pinnules “fit together so neatly and cover the arm-furrow so perfectly that additional plates were scarcely needed.”” A teleological argument of this kind is, however, no proof that the brachial ambulacra are unprovided with plates in Actinocrinus and Platycrinus, when there is a double series on the pinnules which they bear; and, as a matter of fact, the evidence afforded by the Neocrinoids is all against this view. Hyocrinus, Bathycrinus, and Rhizocrinus all have covering plates on the arms as well as on the pinnules (Pl. Ve. figs. 8-10; PL VE figs. 1-4; (Pl. VIL. figs. 2,.7, 85 PL VILL figs. 3."oeee ey iia. ies os PL alee figs. 1-4; Pl X. fig. 20). The first of these has side plates on the pimnules (PI. Ve. figs. 9, 10, sp.), but they are not distinctly differentiated on the arms; and the same is the case in the Pentacrinide and Comatule. But except in Pentacrinus maclearanus 1 Revision, part 1. p. 25. 2 Tbid., part ii. p. 25. 3 Ibid., p. 24, —- REPORT ON THE CRINOIDEA. 65 (Pl. XVI. figs. 2,3; Pl. XVII. fig. 1), with its extraordinarily narrow arm-groove, the ambulacral plating of the pinnule always arises from a similar but less defined skeleton on the brachial ambulacrum (Pl. XVII. figs. 7-9; Pl. XXXIII. figs. 3, 4; Pl XLI. figs. 4,13; Pl. LIV. fig. 7). This is itself directly continuous with the ambulacral plates of the disk; while the perisomic plates, which may appear at its sides (Pl. XX VII. figs. 6, 13; Pl. XLI. figs. 4, 13), are in like manner connected with the anambulacral system over the arm-bases (Pl. XXVI. figs. 1,2; Pl. L. fig. 2). Wachsmuth’s own beautiful observations have demonstrated the existence both of anambulacral and of - ambulacral covering plates on the upper surface of the body, beneath the vault of Actinocrinus; and since the latter also appear on the pinnules, it seems unreasonable to doubt their presence on the arms. But if, as I firmly believe, brachial covering plates occurred in Actinocrinus as in Cyathocrinus, what becomes of the supposed homology between these covering plates in the latter genus and the pinnules of the former type ? Mr. Wachsmuth appears to me to have been much nearer the truth when he suggested that the many little branches of the bifurcating arms in Cyathocrinus performed the functions of pinnules,’ though he gave no explanation as to what these functions were. In recent Crinoids, and most probably therefore in the fossil ones also, the functions of the pinnules are threefold, viz., (1) the protection of the fertile portions of the genital glands, which are all connected together by the sterile rachis in the arm; (2) respiration ; (3) alimentation. Dr. Carpenter’ has pointed out that the Crinoids are very closely dependent for the maintenance of their life upon pure, well aerated water. He alludes to the importance of the pinnated arms in bearing a vast aggregate of tubular tentacles by which respiration is effected; and regards it as probable “that the ordinary pinnules are specially related to the function of respiration, in virtue alike of their proper branchial canals, and of the ambulacral canals and the tubular tentacula with which they are furnished.” This process of respiration was doubtless effected just as well by the tentacles connected with the water-vessels in the many-branched arms of Cyathocrinus, as by those on the pinnules of Actinocrinus or Comatula; and there i8 no reason why the genital glands should not have been contained in these pinnule-less arms, for they frequently extend from the pinnules down into the arms both in Holopus (Pl. Ve. figs. 1, 2, ov.), in many Comatule (Pl. LXI. fig. 3), and even in Pentacrinide ; so that they often appear in section as taking the place of the sterile genital cord, which unites the more fertile portions of the gland that are contained in the successive pinnules. The third great function of the pinnules of a Crinoid arm is to present as large an 1 Notes on the Internal and External Structure of Paleozoic Crinoids, Amer. Journ. Sci. and Arts, vol. xiv. p. 120. 2 Plul. Trans., 1866, pp. 701, 702. 64 THE VOYAGE OF H.M.S. CHALLENGER. area as possible of the ciliated ambulacral grooves on their ventral surface in order to catch the minute organisms in the surrounding water which might serve as food, and send them down the ambulacra of the arms towards the central mouth. For this purpose, as for that of respiration, the repeated branching of the long arms of Cyathocrinus would be as effective as the development of pinnules on the successive joints of less divided arms in other Crinoids. The three great functions of these pinnules would thus have been performed without difficulty by the branching arms of Cyathocrinus. But for which of them are the covering plates of the arm-grooves at all adapted, and how far can these plates be considered as repetitions of the arms on a small scale? To each of these questions only a negative answer is possible. The covering plates of recent Crinoids may be found closed down over the food-groove after déath (Pl. XIII. fiz. 16; Pl XVII. fig. 7; Pl XXVIL fig. 12; Pl XXXIX. fig. 12; Pl. XLVII. fig. 10; Pl LI. fig. 12; Pl. LIL fig. 6; Pl. LIV. figs. 4,6); but they are just as often met with in a more or less erect position, thereby opening the food- groove to the exterior (Pl. Vc. figs. 8-10; Pl. VIIIa. fig. 5—cp. Pl. XVII. figs. 2, 8, 9; Pl. XLVIL. figs. 4, 13; Pl. LI. fig. 11; Pl. LIV. figs. 7-9). Just in the same way the arms are frequently closed round the disk in the dead animal (Pls. XVIII, XIX.,XXV., XXVIIL., XXXL, XLV., XLIX., LIT.) ; while in other cases they are more or less expanded, as they were during life (Pls. XXXIV., XL., XLII.). Messrs. Wachsmuth and Springer argue, however, (1) because the arm-groove of the fossil Cyathocrinus is closed by covering plates which could be opened and closed by the animal (as it is in the dried arm-fragment of Pentacrinus asterius which is shown in Pl. XVII. fig. 7), and (2) because the arm- groove of Actinocrinus must have been perfectly shut off from the surrounding water by the apposition of the pinnules when the arms were closed; therefore the covering plates of Cyathocrinus are homologous with the pinnules of Actinocrinus. But what advantage is it to the animal to have its arm-grooves closed up, whether by covering plates or by pinnules, and so shut off from the surrounding water? It could not breathe properly in this condition, neither could it get its food. None of the food particles which one finds so frequently in the alimentary canal of a Crinoid, e.g., Radiolarians, Foraminifera, Diatoms, &c., could enter the food-grooves of the arms if they were closed by covering plates or by the apposition of the pinnules over them. The habitual expansion of the arms is essential to the whole life of a Crinoid, and Prof. L. Agassiz has well described their movements in the living Rhizocrinus. ‘We had the Crinoid alive for ten or twelve hours. When contracted the pinnules are pressed against the arms, and the arms themselves shut against one another, so that the whole looks like a brush made of a few long coarse twines. When the animal opens, the arms at first separate without bending outside, so that the whole looks like an inverted pentapod; but gradually the tip of the arms bends outward as the arms diverge more and more, and when fully expanded the crown has the appearance of REPORT ON THE CRINOIDEA. 65 a lily of the Lilium Martagon type, in which each petal is curved upon itself, the pinnules of the arms spreading laterally more and more as the crown is more fully open. .. . When disturbed, the pimnules of the arms first contract, the arms straighten themselves out, and the whole gradually and slowly closes up.” ? Taking all these facts into consideration, I cannot but feel that a homology is of no real value when it is based upon the physiological condition of the arm-grooves in the dead animal, and still more in the fossil forms, closed up as they are in every possible way, especially when this condition is one which the living animal only assumes when disturbed, and cannot long maintain without the risk of being both starved and suffocated. The whole poimt of Wachsmuth and Springer’s argument, however, is based upon this closure of the arm-grooves by pinnules and covering plates respectively ; and they attempt to support the proposed homology by certain morphological considera- tions, which must now be discussed. On each side of the brachial ambulacra of Cyathocrinus iowensis there are, according to Wachsmuth,” two rows of minute alternating plates, six to each arm-joint. Pl Vege GOsailoVls figs: 3, 4; PO Xo figs. 73203) Pl LVL fig.. 5). Their rudiments appear in the free-swimming larva simultaneously with those of the basals, which are developed spirally round the right peritoneal tube; while the orals appear in a similar spiral around the left one. The skeleton is at first limited entirely to these two rings of plates, the edges of which meet around the equator of the growing cup, though they ultimately become separated by the appearance of the radials between them. At the base of the closed pyramid formed by the oral plates is the upper portion of the larval body, in the centre of which the opening of the mouth is formed. The rest of the space above the circular lip and beneath the oral pyramid is occupied by the tentacular vestibule. This, according to Goette,’ is derived from the left peritoneal tube, and contains the fifteen first formed tentacles which are borne on the water-vascular ring, At a certain period of development the five valves of this oral pyramid gradually separate so as to open the mouth to the exterior and allow of the protrusion of the tentacles ; while the floor of the original tentacular vestibule, with the mouth in its centre, becomes the peristome of the growing Crinoid. Five of the tentacles correspond to the intervals between the oral valves ; and a conical projection, the commencement of a ray, appears at the base of each of them. The growing rays are supported by the first radial plates, which appear in the rapidly expanding equatorial portion of the body, «e., the band of perisome between the upper edges of the basals and the lower edges of the orals. As the rays grow the second radials appear between the bases of the orals, and the equatorial band continues to increase in diameter. But the orals maintain their original position round the mouth, so that they become completely separated from the basals and radials by the equatorial perisome and are relatively carried inwards, while the second radials project somewhat outwards. The diameter of the oral circlet continually decreases in proportion to that of the disk, which enlarges rapidly as new arm-joints are added in succession. ‘The orals are thus left as a circlet of five separate plates protecting the peristome in the centre of the upper surface of the disk; and the ambulacral grooves extend outwards between the bases of the orals, as the growing rays carry the first formed tentacles away from the water-vascular ring. In all the Pentacrinide, and also in the Comatule, with the single exception of Thaumatocrinus (Pl. LVI. fig. 5), the orals eventually undergo a process of resorption, which commences in the latter case before the young Comatula detaches itself from the larval stem, so that no traces of the orals are to be found in the adult. Neither are there any in the adult Bathycrinus aldrichianus (Pl. VII. fig. 3), nor even in the young Bathycrinus gracilis (Pl. VIIa. fig. 1); though according to the observations of Danielssen and Koren they would seem to be present in Bathycrinus carpenteri, but in a 1 Vergleichende Entwickelungsgeschichte der Comatula Mediterranea, Archiv f. mikrosk. Anat., Bd. xii. p. 621. fe THE VOYAGE OF H.M.S. CHALLENGER. reduced and partially resorbed condition.’ In Rhizocrinus, Hyocrinus, Holopus, and Thaumatocrinus they persist through life, and in each case present a different stage of development. The orals of Holopus retain their embryonic position, and are scarcely separated at all from the first radials, coming into close relation with the inner faces of these plates, while the arms are altogether above and outside them (PI. III. fig. 2). But in Hyocrinus (Pl. Ve. fig. 6, O; Pl. VI. figs. 1-4) and also in Thaumatocrinus (Pl. LVI. fig. 5), though still relatively large, they are separated from the edges of the radials by a marginal zone of perisome which is paved with closely-set plates, and occupies about one- fifth of the total diameter of the disk. The orals appear to be unequally developed in the two living species of Rhizocrinus. In Fhizocrinus lofotensis they would seem either to undergo some amount of resorption, or else to remain in a comparatively undeveloped condition. For they are figured and described by Sars? as minute valvule-like plates which occupy the central ends of the triangular interpalmar fields on the disk; so that there is a comparatively large amount of perisome between their bases and the edge of the disk, just as there is in many young Comatule after separation from the stem. In Rhizocrinus rawsoni, however, they are relatively larger, and their bases approach more closely to the lower brachials, from which they are only separated by a narrow band of perisome (PI. X. figs. 7, 20). Under these circumstances, therefore, it is hardly to be expected that the orals should be preserved in the fossil species of Rhizocrinus; for as they are only united to the calyx by membrane, they would naturally become separated from it when the soft parts were destroyed. In all the recent Comatulz, with the exception of the archaic type Thaumatocrinus (Pl. LVI. fig. 5), they are resorbed before maturity is reached ; and if this was not the case in the fossil species, they probably persisted in somewhat the same form as in Rhizocrinus. Even in Holopus there is no very close connection between the orals and the tubular cup (Pl. III. figs. 1, 2); and the type is so rare in the fossil state, that specimens with the orals preserved are not likely to be found. In the Paleocrinoids, however, the orals reached a greater development than in the later Neocrinoids, resembling rather the solid plates of Holopus and Hyocrinus (PI. III. fig. 2; Pl. Ve. fig. 6; Pl. VI. figs. 1-5) than the mere films of delicate limestone network which represent them in Rhizocrinus and in the Comatule. It will, however, be more advantageous to postpone the discussion of the nature and position of the oral plates in the Paleocrinoids until the chapter which deals with the relation of these older forms to the Neocrinoids. 1 Fra den norske Nordhays-Expedition, Echinodermer, Nyt Mag. f. Naturvid., Bd. xxiii. p. 9. 2 Crinoides vivants, p. 17, figs. 40, 41, 85, 86, 89-91—o. REPORT ON THE CRINOIDEA. 733 B. Tue Perisomatic SKELETON. This name was given by Sir Wyville Thomson’ to “the basal and oral plates, the anal plate, the interradial plates, and any other plates or spicula which may be developed in the perisome of the cup or disk.” He pointed out that the plates of this system are “essentially variable in number and arrangement; most of the minor structural modi- fications throughout the group depend upon the multiplication or suppression of plates of this series. Even in the same species they are by no means constant,” e.g., Antedon rosacea. The nature of the basals and orals has been already discussed; and very little need be said about the anal plate. For although this forms an essential part of the cup of the Pentacrinoid larva of Comatula, and is of extreme importance in its paleontological relations, yet it disappears soon after the termination of Pentacrinoid life, undergoing exactly the same process of resorption as the orals have previously done. It is curious, however, that there should be no special anal plate in Hyocrinus, which has such large orals (Pl. VI. figs. 1-5), while it is also absent in the adult Rhizocrinus, and is perhaps never developed at all; for Sars figures a young individual only 25 mm. long in which the first brachials are comparatively large and form a sort of pyramid, while the second brachials are undeveloped, and he makes no mention whatever of an anal plate.? Whereas in Antedon rosacea the anal plate appears soon after the second radials (which represent the first brachials of Rhizocrinus) ; and it is relatively quite large by the time that the first brachials are developed, forming a nearly complete circle together with the first radials, between two of which it is intercalated. The interradial plates are those minute disks or granules which occur in the substance of the perisome uniting the rays and their subdivisions, and are sometimes difficult to distinguish from the lowest joints of the pinnules. They were first detected in Antedon milleri by J. 8. Miller,’ who figured them as forming one “intercostal” between every two second radials. This was probably due, as remarked by Dr. Carpenter,‘ to his having only employed a low magnifying power in his examination of them. Miiller’ described them as occurring in Pentacrinus asteria (Pl. XIIL. fig. 1), and noticed their difference from the plates on the ventral surface of the disk which are pierced by the water-pores (Pl. XVII. figs. 6, 10). They are very abundant in some species of the Comatulide and Pentacrinide, uniting the rays and their lowest divisions very closely together ; while in other types they may be wholly or entirely absent in some individuals, and more or less well developed in others. In fact, the same individual may have them in one or two of 1 Phil Trans., 1865, pp. 540, 541. 2 Crinoides vivants, p. 27. Tab. iv. fig. 95. 3 This is the Comatula fimbriata of Miller, which occurs in Milford Haven. See his Natural History of the Crinoidea, Bristol, 1821, Frontispiece, fig. 2, G. 4 Phil. Trans., 1866, p. 716. 5 Bau des Pentacrinus, loc. cit., p. 49. (ZOOL. CHALL, EXP,—PART Xxx11.— 1884.) h 10 74 THE VOYAGE OF H.M.S. CHALLENGER. the interradial angles but not in the others. They are, however, very well developed in many of the fossil Neocrinoids, e.g., Marsupites, Apiocrinus, and Extracrinus; and they often have a very solid and substantial appearance. Like the anal plate they are most important in their palzontological relations ; as is also the single calyx-interradial of Thaumatocrinus (Pl. LVI. figs. 1-5), which has been already described (ante, pp. 39-41). The margins of the ambulacra of the disk, arms, and pinnules, and the interpalmar areas of the disk, are rarely, if ever, perfectly free from any traces of caleareous structures. Those of the ambulacra may take the form of simple short spicules which are almost entirely limited to the marginal leaflets ; or they may be forked and branching spicules, or rounded cribriform plates of variable size, which are movable and can either be erected or closed down over the grooves. They are well developed in Hyocrinus, Bathycrinus, and Rhizocrinus (Pl. Ve. figs. 8-10, ep; Pl. VI. figs. 1, 6; Pl. VIL he? cok, Vio digs, goo > abl Wallace. As PL hg PL x. die 20). in the first named genus they are sometimes separated from the dorsal skeleton by other plates which will be noticed later (Pl, Ve. figs. 9, 10, sp); and the same is often the case in the Pentacrinide and Comatulide (Pl. XXXIII. fig. 1; Pl. XLVII. figs. 11, 13; Pl XRTX. fies. 6, 7%; Pl. LL figs 11,12; Pl. LIL fes 5,6; Pl LIV. fies..416-9): These covering plates of the ambulacra of Pentacrinus were termed “ Saumplittchen ” by Miiller, to distinguish them from the uncalcified marginal leaflets of the ambulacra or “Saumlippchen,” which correspond to them in most Comatul ;* while Sars,’ doubting the mobility of these parts in Pentacrinus and Comatula, gave the name “Jamelles du sillon” to the large, oval, and movable plates which border the ambulacra of Rhizocrinus. All three structures, however, are of essentially the same nature. The covering plates of the stalked Crinoids are abundantly represented in many of the Comatule, always, however, resting upon a more or less developed “side plate” as in the Pentacrinide ; and the fact that they are merely an extensive development of the limestone rods and networks in the perisome bordering the ambulacra is evident when all the intermediate stages are examined. All the Pentacrinide have plated ambulacra; but this is by no means the case in the Comatulz, especially in Actinometra ; though individual species of Antedon have a relatively larger and more substantial ambulacral skeleton than any Pentacrinus or Metacrinus (compare Pl. XXVII. figs. 4, 11, 12; Pl. XXXIII. fig. 1; PI XUN IT figs. 11,13); PY LL figs. 11,12; PL LIL figs 5, 6 5 Pi abveses: 4 69). The covering plates which border the ambulacra on the arms and pinnules of Pentacrinus asteria were briefly mentioned by Miiller.2 But he described them as resting upon the joints of the skeleton, which is not always the case; and in fact, two pages further on he spoke of the plates which are situated on the perisome at the sides of the arms and pinnules, just as on that of the disk; while he does not seem to have ? Ueber den Bau der Echinodermen, Abhandl. d. Berlin Akad., Jahrg. 1853, p. 57 (of separate copy). ? Crinoides vivants, p. 24. 3 Bau des Pentacrinus, p. 46. REPORT ON THE CRINOIDEA., 75 noticed the great differences of form, size, and regularity of arrangement between the ambulacral plates of the arms and pinnules respectively. But he pointed out that the covering plates of the disk-ambulacra rest upon other plates which he called “ side plates,” and that both are distinguished from the general anambulacral plating of the disk by the absence of water-pores." It is difficult to individualise these plates when looking at the disk from above, as they are so irregularly arranged (PI. XVII. fig. 6; Pl. XX XIX. fig. 2 ; Pl. XLUI. fig. 3; Pl. L. fig. 2) ; but they are more easily distinguished in a cross section of an ambulacrum (Pl. LIV. fig. 11; Pl. LVII. fig. 3, sp.). Miiller further mentioned a series of median subambulacral plates as lying beneath the food-groove and water-vessel, which he believed to rest in a furrow along their upper surface ;” and he described a series of ambulacral pores between the median row and the side plates, which might be related to the tentacles, and possibly served for the passage of vessels connecting these organs with ampulle. He had previously figured some plates as underlying the sides of the food-groove, with pores in or between them, which he spoke of as “Oeffnungen des Tentakelcanals in die Tentakeln der Tentakelrinne.”* But it is difficult to make out whether they are identical with those which he subsequently described and figured as ambulacral pores.* In reality, however, there are no pores of this kind beneath the ambulacra of the disk; and there are no large ampullee connected with the tentacles as there are with the tube-feet of the Stellerids. But there is often a large amount of calcareous tissue beneath the water-vessels of both disk and arms, which takes the form of more or less regular plates (Pl. LIV. fig. 11; Pl. LVII. fig. 4, swb; Pl. LXII.).. They have no definite arrange- ment, however, and are practically only a portion of the general limestone plating beneath the upper surface of the disk. Although therefore, owing to their subambulacral position, they are generally equivalent to the rotulze of the Urchins, the lancet-plates of the Blastoids, and the radial pieces in the oral rmg of Holothurians, I do not think that they quite deserve the morphological importance which was attributed to them by Miiller. It is possible that the series of plates which were discovered by Prof. Huxley and described by Billings’ as forming an elongated arch beneath the subtegminal ambulacra of Actino- crinus rugosus may be true subambulacral plates. But from the descriptions of them which are given by Meek and Worthen,’ and also by Wachsmuth and Springer,’ I am rather inclined to think that they may be the adambulacral or side plates (Pl. LVIL. fig, 3, sp.). Besides going somewhat fully into the nature of the ambulacral skeleton in Penta- crinus asteria, Miller drew attention, as his predecessors had done, to the plates on the 1 Bau der Echinodermen, p. 58. 2 Thid., pp. 57, 58, Taf. vi. figs. 7, 9, d. 3 Bau des Pentacrinus, p. 70, Taf. ii. fig. 14. 4 Bau der Echinodermen, pp. 58, 63, Taf. vi. fig. 7, ¢. 5 On the Cystidez of the Lower Silurian Rocks of Canada, Geol. Surv. of Canada, Decade iii, p. 27. 6 Notes on the Structure and Habits of the Paleozoic Crinoidea, Paleontology of Ilinois, vol. v. p. 331. 7 Revision, pt. ii. p. 28, 76 THE VOYAGE OF H.M.S. CHALLENGER. interpalmar areas of the ventral perisome. They are continuous over the edge of the disk with the perisomatic plates uniting the rays; and he came to the conclusion that while many of the ventral plates are perforated by water-pores which lead downwards into the body-cavity, these openings are never found in the interradii at the sides of the disk. He termed them “anambulacral” to distinguish them from the “ ambulacralen Kelchporen fiir Fiisschen ;”? and this name has been conveniently extended both to the plates which they pierce, and also to the remaining imperforate plates of the interpalmar areas. Owing to the large size of the oral plates in Hyocrinus, which are themselves pierced by water-pores (Pl. Ve. fig. 6, wp), the number of these anambulacral plates on the disk is very small. But ina large Pentacrinus or Comatula they may be very extensively developed, and the pores are occasionally to be found on the sides of the disk between the rays (Pl. XVII. figs. 6, 10; Pl. XXVI. figs: djo2: IRL EXT Tig. 07% Pl. XXXIV. fig.i2; Pl XXXIX. fig. 2. Pl. LVII. figs. 1, 3, 4; Pl LIX. figs. 2,4, 6—wp ; EIS bexuD.): At the edge of the disk the anambulacral plates of its upper surface pass gradually downwards into the interradials, which are developed in the perisome uniting the rays; so that in some species both of Comatula and Pentacrinus the visceral mass is every- where protected by a continuous armour of plates. Many of the fossil Pentacrinide: and also some species of Apiocrinus show signs of the same structure. It is especially well- marked in the Liassic genus Extracrinus, which had a very large and thickly plated “ventral sac.” In fact the disk of these Crinoids seems to have borne stouter plates than that of many of the Paleozoic Ichthyocrinide ; and I do not understand how the ventral disk of this family, which is described by Wachsmuth? “as composed of a more or less soft or scaly integument, yielding to motion in the body and arms,” can be compared to anything else than the oral surface of a recent Crinoid, with which, however, Wachsmuth says that it “cannot in the remotest degree be homologised.*” I have not seen any good disk of Pentacrinus asteria; but, judging from the condition of its peripheral part in the specimen figured by Miller, I imagine it to have been covered with a continuous pavement of tolerably large plates. This is also the case in Pentacrinus wyville-thomsoni (Pl. XVIL. fig. 6). The interpalmar areas are covered with a very closely-fitting pavement of polygonal plates, the largest of which may be pierced by four or five water-pores, The anal tube, which is plated almost up to its summit, occupies the greater part of the corresponding interradius ; but the anambu- lacral plates which are between it and the mouth (in the specimen figured) are smaller than elsewhere, and less distinctly defined. In fact they look as if they had fused into two uwregularly-shaped plates which abut directly on the peristome. A similar fusion of small plates appears to have taken place on the anal tube of the Metacrinus nodosus 1’ Bau des Pentacrinus, p. 49. 2 Bau der Echinodermen, p. 63. % Revision, pt.i. p. 31. 4 Amer. Journ. Sci., vol. xiv. p. 190. REPORT ON THE CRINOIDEA. 77 represented in Pl. L. fig. 2. It seems at first sight to be perfectly bare, but careful examination proves it to be covered by very closely set small plates with ill defined boundaries. The ambulacra of Pentacrinus wyville-thomsoni form rather prominent ridges, which are composed of four irregular rows of plates. The plates of the two inner rows are somewhat elongated transversely and generally closed down over the grooves, representing the covering plates of the pinnule ambulacra. A well plated disk also occurs in Pentacrinus alternicirrus (Pl. XXVI. figs. 1, 2); but the ambulacra are less heavily plated than in Pentacrinus wyville-thomsoni, and are therefore not so readily distinguished from the anambulacral plates. These are sometimes larger than in the Atlantic species, and are pierced by abundant water-pores which are not shown in the figure; but they do not always fit quite closely together, so that gaps of bare perisome are visible here and there. As in Pentacrinus wyville- thomsoni, the plates are generally larger in the anal interradius than elsewhere. A disk of Pentacrinus naresianus was drawn for Sir Wyville Thomson by Mr. Black (Pl. XXX. fig. 2) ; but it seems to have been mislaid or else cut into sections, for it has not come into my hands. So far as can be judged from the figure, the anambulacral plates were small; while the ambulacra appear to be well-defined ridges and to come jnto close union around a very small peristome, which is thus entirely concealed by the apposition of their large covering plates. I have not seen a disk either of Pentacrinus maclearanus or of Pentacrinus blakei ; but in Pentacrinus miilleri and Pentacrinus decorus it is far from being as completely plated as in the species already noticed (Pl. XVI. fig. 10; Pl. XXXIV. fig. 2). For the anambulacral plates are generally isolated and not in contact with their fellows. They are small and numerous in Pentacrinus miilleri; but in Pentacrinus decorus they are fewer in number and comparatively large, some of them containing as many as twenty water-pores.* There are about four irregular rows of plates on the ambulacra, the imner ones being elongated, and sometimes standing up rather prominently at the edges of the grooves. The relation of the food-groove to the arm-joints varies greatly in the different species of Pentacrinus, so that mere fragments of the arms can be identified by the characters of their ambulacra, quite apart from any peculiarities of their arm- and pinnule- joints. The middle line of the upper surface on each joint of the brachial skeleton is occupied by a groove of variable depth and width, to which Miiller gave the name “ arm-groove ” (Pl. XVIL figs. 1, 4, 7, 8, 9). It is bordered on each side by the more or less prominent muscle plates of the successive joints; and the vascular structures which are partially 1 These are omitted in the figure, and the plates are drawn too close together. 78 THE VOYAGE OF H.M.S. CHALLENGER. contained in it are continued from one joint to another between the two large muscular bundles that unite them. In Antedon eschrichti and in many other Comatulz, more especially those belonging to the genus Actinometra, this arm-groove merely lodges the lowest part of the cceliac canal; while the genital cord, with the water-vascular and blood-vascular trunks and the ambulacral epithelium, are all situated above the arm- groove, and separated from it by a variable amount of intervening perisome, so that little more than half the vertical height of the arm is due to its dorsal skeleton. The lower parts of the arms in Metacrinus murray: present a somewhat similar condition (Pl. XLI. fig. 13). In other Comatulz, however, and in Pentacrinus a great part, sometimes even the whole, of the soft parts of the arm are lodged within the groove on the upper surface of the skeleton (Pl. XVII. figs. 1, 4; Pl. XXVII. fig. 6); and there is no substantial ventral perisome in the ordinary sense of the word, or it is reduced to a mere film, sometimes thinly plated, which covers up the muscular bundles. In many species, and especially in the small deep-sea Comatulee, this layer of perisome is excessively thin and transparent, so that the food-groove appears to rest upon and between the muscular bundles. In some of the tropical Antedons, however, it bears a continuation of the anambulacral plates of the disk, and this is also the case in Pentacrinus wyville-thomsoni, Pentacrinus alternicirrus, Pentacrinus naresianus, and Pentacrinus blaket (Pl. XVII. fig. 4; Pl. XXVII. figs. 6,13; Pl. XXXIIL. fig. 3). The third of these, Pentacrinus naresianus, has the greatest development of this plated perisome on the arms (Pl. XXVII. fig. 13). It is continuous from one pinnule socket to the next on the same side, so as to cover in both the muscular bundles and also the upper surface of the intervening arm-joint; and the ambulacra are thus distinctly above and outside the arm-groove. They are bordered by large oval covering plates which overlap alternately from opposite sides, and are continued on to the pinnules (Pl. XXVII. figs. 11, 12). These plates do not rest directly upon the pinnule-joints, but are separated from them by a thin limestone band which is a continuation of the lateral plating of the arm. It does not, however, exhibit any differentiation into side plates, though its edges are cut out into alternate teeth and notches (Pl. XXVII. fig. 11). The latter are occupied by the — tentacles, but can be closed, or nearly so, by the covering plates which rest on the intervening teeth. In the arms of Pentacrinus blakei (Pl. XXXIII. fig. 3) the sides of the joints bend inwards towards the middle line more than they do in Pentacrinus naresianus, so that the arm-groove is narrower, and the ambulacrum practically coincides with it instead of lying above it. It is bordered by long plates which are really the covering plates fused with the side plates. When they pass on to the pinnules the former become more differentiated, but the latter lose their individuality and become parts of a con- tinuous denticulated band just as in Pentacrinus naresianus (Pl. XXXIIL. fig. 1). REPORT ON THE CRINOIDEA. 79 A somewhat different type of ambulacrum is presented by two other Caribbean species, Pentacrinus asteria and Pentacrinus decorus. The arm-groove of the former is relatively wide and the proximal parts of the ambulacra are distinctly above it, though they gradually sink down into it as they get farther from the disk; as long as the rays continue to divide their ambulacra and those of their pinnules are covered by an irregular double row of large plates (Pl. XIII. fig. 16; Pl. XVII. fig. 7), After the last bifurcation these plates become smaller and more regularly arranged, so that they take the form of oblong covering plates with rounded ends which stand up at the sides of the groove (Pl. XVII. fig. 8). They do not, however, extend uninterruptedly along each side of the groove, but are arranged in a series of linear groups between the successive pinnules of either side, so that they alternate in position on the two sides of the arms successively. They are largest and best developed at the base of a pinnule, where its ambulacrum comes off from that of the arm, and from this point they diminish gradually in size towards the disk until the base of the next pinnule is reached, when a fresh set appears upon the proximal edge of its ambulacrum. Thus, then, the covering plates which pass on to the pinnule-ambulacrum from that of the arm are at first limited to its proximal or outer side only. But a second set soon appears on the inner side of the ambulacrum ? (7.¢., that next the arm), and their outer ends gradually become more and more rounded until they present the appearance shown in Pl. XIII. fig. 15. Their bases are all fused into a narrow band of limestone which rests on the pinnule-joint and represents the side plates that are better developed in other species; while the rounded outer portions represent the covering plates proper, which alternate with one another from opposite sides, so as to leave a series of openings through which the tentacles are extended. The lower portions of the ambulacra of Pentacrinus decorus are essentially like those of Pentacrinus asteria, except that they sink more deeply into the arm-groove, while the plates covering them are smaller and far less regularly arranged (Pl. X XXIII. fig. 6). But the muscle plates of the successive arm-joints fit less closely together than in most other species of Pentacrinus, so that the muscular bundles are long and also visible externally ; for they are not covered in by plated perisome as in the allied Pentacrinus blakec (Pl. XXXIIL. fig. 3). In the middle and outer parts of the arms the ambulacra are generally like those of Pentacrinus asteria, thbugh not so open (Pl. XXXIII. fig. 4) ; for the groups of plates which protect the bases of the pinnule-ambulacra overlap somewhat closely from opposite sides, while their parts are more distinctly differentiated. Farther out on the pinnules the segmentation of the lateral limestone band is sometimes carried so far that the side plates can be distinctly individualised ; but there is a good deal of variation in this respect (Pl. XXXVII. figs. 23, 24). A third type of arm, with a very narrow median groove to which the ambulacrum is 1 Compare Pl, XVII. fig. 3; Pl, XLVII. fig, 11. 80 THE VOYAGE OF H.M.S. CHALLENGER. almost entirely limited, is presented by the four species Pentacrinus miilleri, Pentacrinus maclearanus, Pentacrinus wyville-thomsoni, and Pentacrinus alternicirrus. The nearest approach to Pentacrinus asteria is to be found in Pentacrinus miillert (Pl. XVII. fig. 9), as might be expected for various reasons. The arm-groove is narrower, but the covering plates which rest on its edges pass up on to the pinnules alternately from opposite sides very much as in Pentacrinus asteria ; though the successive groups do not overlap one another so much as in that type, and there is more differentiation of the side plates upon the pinnules (Pl. XV. figs. 7,8). In Pentacrinus wyville-thomsoni the arm-groove is still narrower, and the ambulacrum almost entirely withdrawn into it (Pl. XVII. fig. 4). The plates bordering it are smaller and more irregular than in Pentacrinus miilleri, and more distinetly limited to the pinnule-bearing side of the arm; while the intervals between the joints are larger and covered by small irregular plates as in Pentacrinus naresianus and Pentacrinus blakei. The plating of the pinnules is limited at first to their outer sides (Pl. XVII. fig. 3); but it eventually appears on the inner sides as well, and becomes differentiated into covering plates resting on a limestone band which is sometimes imperfectly separable into side plates (Pl. XVII. fig. 2). A further reduction in the width of the arm-groove and in the size of the plates at its edges appears in Pentacrinus alternicirrus (Pl. XXVII. fig. 6). The intervals between successive joints which are occupied by the muscular bundles are larger than in Penta- crinus wyville-thomsoni, and are more distinctly plated. The rudimentary covering plates are limited to the origins of the pinnule-ambulacra, and a short distance behind them ; so that between every two pinnule-ambulacra of one side there is a short space of unprotected arm-groove. As in Pentacrinus wyville-thomsoni, the bases of the pinnule- ambulacra are plated on the outer side only, and in their distal portions the lateral band on which the covering plates rest is not divided into side plates (Pl. XXVII. fig. 5). Lastly, in Pentacrinus maclearanus the arm-groove is extraordinarily narrow, and bounded by little else than the broad plate-like upper surfaces of the component joints (Pl. XVII. fig. 1), while the covering plates are almost entirely limited to the pinnules (Pl. XVI. figs. 2, 3). They are relatively small, and the lateral band supporting them, though broad at first, soon narrows away considerably. The disk of Metacrinus presents much the same variations in the extent to which it is plated as that of Pentacrinus does. In Metacrinus nobilis (Pl. XLIII. fig. 3) there is a tolerably continuous pavement with well defined ambulacral ridges. These are bounded by about four rows of plates, those of the two inner rows being transversely elongated, and alternating with one another. In other types the anambulacral plates are more isolated as in Pentacrinus decorus, being more closely set, however, along the sides of the ambulacra, which are covered by longish plates. This is the case in Metacrinus angulatus (Pl. XXXIX. fig. 2), Metacrinus cingulatus, and Metacrinus nodosus (Pl. L. fig. 2). The scattered arrangement of the anambulacral plates is not well represented in the last ™ REPORT ON THE CRINOIDEA. $1 mentioned figure ; and it is too small to show the very numerous water-pores piercing the ‘plates, some of which have as many as twelve or fifteen openings. They are much less abundant in Metacrinus cingulatus and Metacrinus angulatus (Pl. XX XIX. fig. 2), while the plates are also smaller. The disk of Metacrinus differs from that of Pentacrinus in the greater irregularity of its ambulacra; the branches of which proceeding to the large lower pimnules often come off directly from the primary groove-trunks, or even from the peristome itself. This is especially well shown in Metacrinus angulatus and Metacrinus nobilis (Pl. XXXIX. figs: 2): Plo XM tie: 43)- Another point of difference is the relatively larger size of the anal tube in Metacrinus, which is well shown in Metacrinus nodosus (Pl. L. fig. 2). It may occupy the whole of the interpalmar area in which it lies, and is often considerably inflated, so as to be a somewhat prominent object on the surface of the disk. It is erroneously represented as perfectly bare in the figure of Metacrinus nodosus, and this actually seems to be the case at first sight. Closer examination shows, however, that its apparent bareness is really due to the smoothness and very close approximation of the plates which cover it."" They are thinner than the corresponding plates in the other interpalmar areas, and form a smooth continuous pavement over the whole of the lower part of the tube, becoming more nodular and irregular towards the top. The whole appearance of the anal tube in this species forcibly recalls Buckland’s well known figure of the “abdominal integument” of Extracrinus briareus.? There are indications of this close pavement on the anal tube of Metacrinus nobilis (Pl. XLUL. fig. 3); and it is better shown im a curious specimen of Metacrinus angulatus (Pl. XXXIX. fig. 2), which has a smaller supplementary anal tube by the side of the larger one. The plates of the pinnule-ambulacra in Metacrinus are better differentiated on the whole than those of Pentacrinus. For in the outer parts of the pinnules, at any rate, the covering plates rest upon a row of distinct side plates (PI. XLVIL fig. 11; PL LL fies, 11, 12; Pl. LIL. figs. 5, 6), and not upon an almost undivided band of limestone as in most species of Pentacrinus (Pl. XIII. fig. 15; Pl. XXXVIL fig. 23). In the lower parts of the rays and arms the anambulacral plating of the disk extends outwards at the sides of the ambulacra, in which the arrangement of plates is confused and indefinite (Pl. XLI. fig. 13). Farther out, however, where the zig-zag course of the ambulacrum (still distinctly above the arm-groove) is more marked, and the ambulacral plates less abundant, the elongated shape of the plates immediately bordering the groove is more distinctly visible (PI. XLI. fig. 4). In most species their extremities gradually become bifid, as is well shown in Metacrinus angulatus and Metacrinus murray: (Pl. XXXIX. fig. 13; Pl. XLI. fig. 14). Both of these, especially the former, have the 1 See the remarks on the disk of Pentacrinus wyville-thomsont, ante, p. 76. 2 Geology and Mineralogy, vol. i. p. 439 ; vol. ii. pl. 51. fig. 2. (ZOOL. CHALL. EXP.—PART XXxi1.—1884.) li ll 82 THE VOYAGE OF H.M.S. CHALLENGER. ambulacra well above the level of the arm-grooves; and there are no other plates on the arm than the covering plates which really belong to the pinnule-bases, while the muscular bundles are freely visible at the sides of the ambulacra. But in other species, such as Metacrinus nobilis (Pl. XLL fig. 11), the food-groove is more concealed within the arm-groove, and the forked covering plates are less abundant at the pinnule-bases. Farther out on the pinnule, the proximal half of the fork becomes gradually less and less prominent ; and it is eventually absorbed into the basal part of the plate, which thus represents a side plate; while the distal half of the fork, becoming larger and better defined, separates itself off as a rounded covering plate (Pl. XLI. fig. 12; Pl. XLVII. fig. 11). The branches of the ambulacra which pass on to the massive basal joints of the prismatic lower pinnules are usually but little plated, as is the case in Pentacrinus asteria (Pl. XIII. fig. 16; Pl. XLI. figs. 4, 12,13; Pl XLVIL fig. 13; Pl LI fig. 12). But beyond the first two joints the plating reappears; and the four rows of plates become gradually developed from the irregular plates at the sides of the groove, which come to assume a definite form and break up into covering plates and ill defined side plates. The gradual differentiation of side and covering plates upon the pinnules from the single forked plates at the sides of the brachial ambulacra takes place in this way in most species of Metacrinus; but the four rows are never so distinctly separable as in the Comatulee (Pl. LIV. figs. 4, 6-9). A slight variation of this process occurs in Metacrinus costatus (Pl. XLVII. fig. 13; Pl. XLIX. figs. 6,7); while Metacrinus murrayi and Metacrinus nodosus (Pl. XLL fig. 12; Pl. LI. fig. 12) are the intermediate links between this species and the other types of Metacrinus. The bases of the pinnule-ambulacra just beyond the wide lower joimts are bordered by a series of rounded plates, which are deeply hollowed in the centre so that their edges stand up rather prominently. The first eight or ten of these are attached to the pinnule-joints on each side by a continuous band of limestone. This gradually becomes absorbed into the raised proximal edges of the rounded plates so as to form the side plates; while the distal halves eventually separate themselves off as the covering plates (Pl. XLVI. fig. 13). The side plates only become properly differentiated in the outer parts of the lower pinnules, and in the later pinnules on the arms (PI. XLIX. figs. 6, 7); but they retain a more or less prominent backward process, which is the remains of the raised hinder edge of the rounded plates on the proximal parts of the ambulacra. Although there are no side plates on the arms and pinnule-bases of Hyocrinus, yet they are large and well developed on the enlarged portions of the pinnules which contain the genital glands (Pl. Ve. fig. 10, sp). The proximal ones, taking the place of numerous small anambulacral plates, are smaller than their successors, which considerably increase the depth of the body-cavity within the pinnule. Distally, the side plates gradually diminish in size and finally disappear altogether, so that the covering plates come to rest directly on the edges of the pinnule-joints (PI. Ve. figs. 8, 9). REPORT ON THE CRINOIDEA. 83 In many of the tropical Comatul the pinnule-ambulacra are fully as well or even better plated than those of the Pentacrinide. Antedon acoela and Antedon inequalis,' both from Stations where Pentacrinidze are abundant, are good instances of this (Pl. LIV. figs. 4, 6-9). The differentiation of side plates and covering plates is more complete ; and the plates themselves are not only larger relatively to the pinnule-joints, but also absolutely so. When the covering plates are erected and the groove opened, as shown in Antedon inequalis (Pl. LIV. fig. 8), the tentacles are extended between them. But the tentacles can be completely retracted and the plates closed down so as to convert the grooves into tunnels, as shown in Antedon acoela (PI. LIV. fig. 4). In the distal edge of each of the side plates is a small rounded notch, so that there is a series of gaps along each side of the ambulacrum, one between every two plates. These lodge the problematical “ sacculi” which are so characteristic of the genus Antedon. In those Comatule with plated pinnules which have short and rounded genital glands, instead of the long fusiform structures characteristic of Antedon eschrichti, Hyo- erinus, and the Bourgueticrinide, there is sometimes a curious modification of the perisomatic skeleton on the genital pinnules. The enlarged part of the pinnule is protected by a very strongly developed anambulacral plating, which is much more regular and closely set than that of the disk and arm-bases, especially in the case of Antedon acoela (Pl. LIV. figs. 1-3). Resting upon the four or five middle joints of the short pinnules there is a double row of large plates, which are rectangular at the base but somewhat more irregular in shape at their upper ends. There are generally five or six plates in each row; but those of the two sides have no fixed relative positions, sometimes corresponding exactly, and sometimes alternating as exactly. They have the same protective function and very much the same appearance as the large side plates of Hyocrinus (Pl. Ve. figs. 9, 10, sp), but differ from them in two ways. In other species of Antedon, such as Antedon angusticalyx and Antedon incerta (BE ALLY, figs. 5, 6), these protecting plates are smaller and more irregular than in Antedon acoela; while in Antedon incerta the two rows are separated by the ambulacrum with its well developed side and covering plates. But im Antedon angusticalyx and in Antedon acoela these swollen lower pinnules receive no branches from the brachial food-groove, Just as 11 many species of Actinometra; and the anambulacral plates covering the genital glanas consequently meet one another in the medio-ventral line of the pinnule above the gland within. The sacculi, however, which he at the sides of the ambulacra may extend on to these grooveless pinnules, and occupy small holes between the large protecting plates; while in the outer joints of the pinnules, beyond the glands, the sacculi occupy the median groove on the upper surface of the skeleton, as is well shown in Antedon angusti- calya (Pl. LIV. fig. 5). 1 The specific formula of this typeis— A. 8(1. or 2p.) e : 84 THE VOYAGE OF H.M.S. CHALLENGER. It is curious that these protecting anambulacral plates on the genital pinnules of Antedon acoela should be so largely developed,’ while those which cover the inter- palmar areas of the disk are comparatively small and irregular in character (PI. LV. fig. 5). In many Comatulz, however, the disk is very closely plated, both in the ambulacral and in the interambulacral areas. The plates of the latter are mostly small, and rarely pierced by more than one water-pore ; while the ambulacra are generally marked by an irregular double row of transversely oblong plates, as in Antedon angusticalyx (Pl. LV. fig. 6). But these are sometimes barely distinguishable from the anambulacral plates, and the whole set encroach very much upon the peristome, so that it is scarcely visible in the dry state, as shown in Antedon basicurva® (Pl. LY. fig. 7). This is still more marked in Antedon acoela (Pl. LV. fig. 5). Both the ambulacral and the anambulacral plates are palisade-like in form, as the former are in Pentacrinus decorus (Pl. XXXIV. fig. 2); and they are very much crowded, so that the course of the food-grooves can only be made out with difficulty even in spirit specimens, while the peristome is frequently entirely invisible. The disks of the three Antedon species just mentioned are very much incised between the ambulacra, so that they are markedly stellate in form. The arrangement of the coiled digestive tube is consequently much less complex than in large disks like those of Antedon eschrichti or of Pentacrinus, which have the rays united by perisome so as to increase the capacity of the cup; while the interradial spaces are filled up with connec- tive tissue which supports extensions of the digestive tube. In some species of Antedon with an incised disk the anambulacral plates are somewhat squamous, with a tendency to overlap one another. This is the case, for example, on the disks represented on Pl. LY. figs. 3,4. They probably belong to Antedon multiradiata,? having been dredged at Cape York in an isolated condition, together with entire indivi- duals of this species. The edges of the interpalmar areas rise rather sharply towards the ambulacra, which are marked by strong ridges with indications of a median groove visible upon their upper surface. The food-groove beneath is really comparatively deep, with its edges plated somewhat regularly and turned in towards one another. ‘This is very marked in the immediate neighbourhood of the peristome, which is thus completely closed. 1 The position of the plates which protect the genital glands as regards the pinnule-joints, and the very regular appearance which they frequently present, have led me to think that the so-called “rudimentary pinnules” of Cyathocrinus longimanus, Angelin, may possibly be of the same character, and not ambulacral side plates more largely developed than usual (see chap. iv. pp. 62-66). A comparison of Angelin’s figures of these structures as seen from the side and from above (Tab. xxvi. figs. 4b, 4c), with the corresponding views of the protecting plates in Antedon acocla (PL LIV. figs. 2, 3), shows a remarkable similarity in their number and general arrangement. In the recent form, however, these plates are on the pinnules, while those which they appear to resemble in the Paleozoic Cyathocrinus are on the arms. But as these bear no pinnules, and must therefore have themselves contained the genital glands, the difference between the two structures is not so great as it would seem to be at first sight. ? The specific formula of this type is—A. 10. = . 5 The specific formula of this type is—A.R.3.3. = : REPORT ON THE CRINOIDEA., 85 It is concealed in the smaller specimen by the large and prominent anal tube which pro- jects forwards over it. The original of Hyponome sarsii, the “recent Cystidean,” was the disk of a plated Antedon, very probably of this species, Antedon multiradiata. Allusion has already been made to the frequency with which these disks are met with in an isolated condition ; and their resemblance to the curious Paleozoic forms Agela- crinus, Lepidodiscus, &e., is very striking. I know that Sir Wyville Thomson had a suspicion whether these problematical organisms may not have been the separated disks of some one or other of the numerous Palocrinoids, as suggested by Lovén and Liitken.* Deep ambulacral grooves with strongly plated sides are also met with on the disk of Actinometra strota. This species is very common at Cape York, and its disk, which was also obtained in an isolated condition, may be nearly bare, or plated very completely, as is shown in Pl. LIV. fig. 10, and Pl. LV. fig. 2. The whole of the large interpalmar area in which the anal tube is situated is covered with more or less scaly plates, which become stouter and more granular in the neighbourhood of the subcentral anal tube. The sides of the deep ambulacra are bounded by numerous smaller plates without any definite arrangement. But they are strictly limited to the disk, not extending on to the arms. The large size of this armature, relatively to the tentacles and the ambulacral groove proper, is well shown in the cross-section represented in Pl. LIV. fig. 11. Much of it extends beneath the water-vessels, and corresponds to what Miiller called the subambulacral plates of Pentacrinus’ (Pl. LXILI.). Actinometra jukesi is another species which is common at Cape York. The large anal area is often beset with numerous irregular plates, many of which bear nodules of variable size (Pl. LV. fig. 1). They are smaller on the base and sides of the anal tube; and there are few or none in the small interpalmar spaces between the edge of the disk and the circumferential ambulacra, which are themselves devoid of supporting plates, though deep like those of Actinometra strota. Some species, both of Antedon and Actinometra, have the ventral perisome of disk and arms entirely devoid of any continuous plating; though this may be strongly developed between the lower divisons of the rays, sometimes extending up to the level of the third axillary. C. Tue ViIscERAL SKELETON. I use the term “ visceral skeleton” to denote the numerous spicules and networks of limestone which occur more or less plentifully in the bands of connective tissue that traverse the visceral mass of the Comatule. It also includes the more or less regular plates, often quite well defined, which occur within the disk of Pentacrinus. They are 1 Canad. Nat., 1869, p. 268. 2 Bau der Echinodermen, pp. 57, 58, Taf. vi. figs. 7, 9, d. 86 THE VOYAGE OF H.M.S. CHALLENGER. formed, like the anambulacral plates, of a calcareous network interpenetrated by an organic basis, which is of the same nature as in the joints of the rays and arms (Pls. LVIIL, LXIZ.). The simple spicules and thin networks of limestone which occur in the less heavily plated disks are especially abundant in the visceral layer of the peritoneum. ‘This is well seen in those Crinoids, such as Antedon rosacea’ and Actinometra strota, in which there is but little connection between this visceral layer and the parietal one lining the interior of the cup, so that the entire visceral mass is readily detached from the calyx. Unlike that which lines the cup, the oral perisome is usually very closely adherent to the visceral mass, and cannot be separated from it without some trouble. The peritoneal covering of the latter also contains limestone deposits, so that sections through the upper part of the disk show two layers of plates and spicules. The upper one is in the perisome itself, and belongs to the anambulacral system; while the lower belongs to the upper surface of the visceral mass. These lower plates were described and figured by Miiller.? Together with those of the sides and lower parts of the visceral mass they seem to be the modern representatives of the so-called ‘“intervisceral plexus” which lined the cup of the Actinocrinide. Wachsmuth * has pointed out that in some members of this family “almost the entire test is lined with a delicate calcareous plexus or network. This lining is not in contact with the test directly, but connected with it by small partitions, producing innumerable little chambers, which communicate with each other and with the visceral cavity.” It rarely extends below the level of the second radials, and passes gradually upwards into the plates, coating the interpalmar areas on the upper surface of the disk below the vault. These, which extend right up to the edge of the peristome, are of course anambulacral in character, and it is not easy, any more than it is in Pentacrinus, to say where the one set begins and the other ends. But so far as the lower part of the cup is concerned, the intervisceral plexus of the Actinocrinide is merely a greater development of the limestone deposits in the visceral layer of the peritoneum of recent Crinoids. All of these have more or less abundant plates and spicules in the connective tissue which lies beneath the peristome and supports the lip, and also in that which unites the coils of the digestive tube (Pl. LXII.). In the regular endocyclic Crinoids this organ makes rather more than a single round turn upon itself (fig. 2 on p. 89); and it is the aggregation of limestone deposits upon its central side which forms the so-called “columella,” once regarded as a sand canal. This supporting skeleton of the digestive tube, like that enclosing the visceral mass, was much better developed in the Actinocrinide than in recent forms. Occupying 1 Ludwig (op. cit., p. 330, Taf. xix.) has given an excellent diagrammatic section of this type, in which this point is well illustrated. 2 Bau der Echinodermen, p. 58, Taf. vi. fig. 9, f- 3 Revision, part ii. p. 26. SORES Pa PM hres ee ee AN REPORT ON THE CRINOIDEA. 87 the greater part of the interior of the cup, but not reaching down to the basals, is a large convoluted organ, which has a general resemblance to the shell of a Bulla. It is open at both ends, and its longer axis nearly coincides with that of the body of the Crinoid. Wachsmuth and Springer’ describe its wall as being “simple in all cases, very delicate, and constructed of an extremely fine filigree work, which generally in the fossil became thickly incrusted with siliceous matter on both sides.” Hall, who was the first to notice this organ, made no suggestions respecting its nature. Meek and Worthen supposed it to be a kind of framework supporting the coiled digestive tube ;? while Wachsmuth and Springer suggest that it might be “an extensive plexus of blood-vessels surrounding the ambulacral (!) canal;” and desiring that it “should receive a more appropriate name than any yet given,” they propose to call it the “‘ cesophageal network.”* That it supported some of the intervisceral blood-vessels I have very little doubt ; but there is no reason to suppose that it actually represents the vessels themselves, which would have passed through the meshes of its network (compare Pl. LVIL fig. 5). As a similar though less developed structure occurs in recent Crinoids, I see no reason to doubt the correctness of Meek and Worthen’s determination. Neither do I think Wachsmuth and Springer’s name a good one, for it implies that the structure in question was connected with the cesophacus, and not with the rest of the digestive tube. But as it is so large, relatively to the interior of the calyx, the remainder of the digestive apparatus must in that case have been quite small, which is improbable for many reasons. According to Meek and Worthen,* “its slightly dilated upper end seems to stand with its middle almost, but apparently not exactly, under the middle of the nearly central proboscis of the vault; while at the anterior side of its upper margin, and a little out from under the proboscis, it shows remains of a kind of thickened collar, which we found to be composed of minute calcareous pieces. From this there radiate five ambulacra, composed of the same kind of minute pieces as the collar itself.” The thick collar was the edge of the peristome with its more or less regular supporting plates as in any recent Crinoid. The mouth was placed within this peristomial space, and the greater part of the convoluted organ would thus have lain altogether behind it. The direction of its spiral is exactly the same as that of the digestive tube in Antedon or Pentacrinus, as may be seen by comparing Dr. Carpenter's figure of the latter’ (viewed from above) and the “inferior end view” of the convoluted organ given by Meek and Worthen.’ I believe that the gullet ran downwards and backwards as it does in Pentacrinus; and that the intestine, after following the convolutions of its support, turned upwards again to end in the long anal tube, the so-called “ proboscis.” 1 Revision, part ii. p. 35. 2 Paleontology of Illinois, vol. v. p. 329. 3 Revision, part ii. p. 35. 4 Paleontology of Illinois, vol. v. p. 331. 5 Proc. Roy. Soc. Lond., vol. xxiv. pl. viii. fig. 1. § Paleontology of Illinois, vol. v. pl. ix. fig. 120. rip es a) 88 THE VOYAGE OF H.M.S. CHALLENGER. VL—THE MINUTE ANATOMY OF THE DISK AND ARMS. I do not propose to treat the subject of this chapter as fully as I have done the comparative morphology of the Crinoid skeleton. Much has been written about it lately, and a general resumé of this recent work, together with some independent observations of my own, was published in the Quart. Journ. Micr. Sci. for April 1881. Since that time I have been able largely to increase the range of my observations on the anatomy of the Comatule, and have also extended them to Pentacrinus, Bathycrinus, and Rhizocrinus. The result has been that I am able to confirm in almost every respect the admirable investigations of Ludwig on the minute anatomy of Antedon rosacea." On the other hand, there are some points, notably in the relations of the axial cords of the skeleton, which were entirely overlooked by him; while he also omitted to describe some remarkable peculiarities in the structure of the plexus of blood-vessels which is situated in the lip, and is connected with the oral blood-vascular ring. It is only fair to state, however, that my new observations upon the nervous and vascular systems of this type owe their origin, in great measure, to my having been able to examine other species in which the peculiarities in question are much more developed than they are in Antedon rosacea. A. THE GEOGRAPHY OF THE DIsK. I find that it is most convenient, on the whole, to use the terms right and left precisely as in human anatomy. When the ventral surface is upwards, with the mouth north, or pointing away from the observer, and the anus posterior, the right side of the disk would be west in a map, and the left side east (figs. 2, 3). On the other hand, when the dorsal surface of the skeleton is upwards, the anal area being, of course, posterior, the eastern rays are those of the right side, and the left rays are in the west. The same method applies to the arms, a pinnule on the right side being east in a dorsal view, and west in a ventral one. B. Tue Digestive TusE. Little need be said about the alimentary canal, the general course of which alters but slightly in the endocyclic Crinoids (Antedon, Pentacrinus, Rhizocrinus, &c.), though it varies a good deal in the complexity of its cavity. Both in Antedon rosacea and in Antedon eschrichti the gullet runs downwards and backwards, trending slightly to the 1 Op. cit., Zeitschr. f. wiss. Zool. 1877, Bd. xxviii. pp. 255-353, Taf. xii.—xix. Pt Des REPORT ON THE CRINOIDEA. 89 left. When it has reached the bottom of the visceral mass the intestine turns off to the right, and coils round its anterior side. It follows the watch-hand, until it has reached the hinder part of the disk, behind the commencement of the first coil (fig. 2). Here it turns upwards and slightly forwards, to end in the anal tube. The spiral form of the whole organ is thus almost identical with that of the so-called digestive organ in the Palzocrinoids, which I believe to be nothing but the more or less calcified connective tissue that supported the intestinal wall, as explained in the previous chapter. In simple forms, like Rhizocrinus and Bathycrinus, more especially the former, the development of the gut is but slightly more advanced than it is in the Pentacrinoid. Horizontal sections through the lowest part of the cup of the larva are remarkably similar to corresponding sections of Rhizocrinus and Bathycrinus, such as are represented in Pl. VIIb. figs. 6, 7, and Pl. VIIIa. fig. 8. Fic. 2.—Diagram showing the course of the Digestive Tube in an endocyclic Crinoid (Antedon, Pentacrinus, &c.), as seen from the ventral side. A, B, C, D, E, the five ambulacra of the disk ; m, mouth ; @, anus. The lower part of the cup between the second radials is occupied in Bathycrinus and in the Pentacrinoid larva by a large expansion of the lowest portion of the coiled gut, just as described in Rhizocrinus by Ludwig.’ It is somewhat kidney-shaped in section, and the concavity is occupied by the plexiform gland, which is always inter- radial in position where it comes out of the calyx (Pl. VIIb. fig. 6, x). At the level of the third radials of Bathycrinus, or the second brachials of Rhizocrinus, the circular course of the intestine is more apparent, and the plexiform gland is separated from the body-wall by the rectum, as shown in PI. VIIb. fig. 7, and Pl. VIIla. fig. 8. In both of these figures the « indicates the plexiform gland, which is here situated just below (¢.e., south of) the lower end of the fore-gut, where it passes into the mid-gut or intestine generally. ' Zur Anatomie des Rhizocrinus lofotensis, M. Sars, Zeitschr. f. wiss. Zool., 1877, Bd. xxix. p. 64. (ZOOL. CHALL. EXP.—PART XXx11.—1884.) Ti 12 90 THE VOYAGE OF H.M.S. CHALLENGER. The further course of the rectum is shown in Pl. VIIb. fig. 8, which represents a section through the upper part of the disk at the level of the articulation between the first and second brachials ; and the last trace of the plexiform gland (z) is seen between the fore-gut and the final coil of the intestine. Both Rhizocrinus and Bathycrinus exhibit a peculiarity in the relations of the digestive tube and visceral mass which does not appear in the Pentacrinoid. The large crests at the sides of the arm-groove in the second brachials of Rhizocrinus, which were well figured by Sars," have always been a puzzle to me, for they are something more than unusual developments of the muscle-plates at the distal end of the joint. Horizontal sections of the cup show, however, that they support the sides of comparatively large interradial diverticula from the intestinal coil, the outer ends of which are overlapped to some extent by the broad dorsal surfaces of the brachials (Pl. VIIIa. fig. 8). The first traces of these extensions of the digestive cavity appear in Rhizocrinus lofo- tensis at the level of the muscle-plates of the first brachials, by which they are in a great measure supported. They become more independent of the skeleton at the syzygy with the second brachials ; but enter into close relations with these joints at their distal ends, where the crests on the ventral surface become more prominent. They are much more marked in some individuals than in others, but the outline of the visceral mass is always distinctly pentagonal, even if its angles be not produced outwards, so as to give it a stellate appearance. The same peculiarity appears in Bathycrinus. The crests on the radial axillaries are large, wing-like processes, altogether distinct from the muscle- plates to which the first brachials are attached, as is shown in PI. VII. fig. 4a, and Pl. VIIa. fig. 17; and they afford a large amount of support to the interradial diverticula of the gut (Pl. VIIb. fig. 7). These develop themselves gradually from below upwards, no trace of them appearing below the articulation of the second and the axillary radials; but indications of them are still visible at the upper part of the first brachials, as shown in Pl. VIIb. fig. 8. In this figure, too, may be seen the earlier and simpler stages of that plication of the inner or adcentral wall of the gut which is so much more marked in Pentacrinus, and still more so in the Comatule, especially in Antedon eschrichti, Promachocrinus, and allied forms (Pl. LVIII. figs. 4-6). The disk of the Comatulz is generally flatter than that of the stalked Crinoids, and is almost entirely independent of any lateral support from the second radials. These lie beneath more or less of its dorsal surface, but do not protect its sides. The descending portion of the fore-gut is therefore comparatively short, and the coiled intestine into which it passes lies spread out on the upper surface of the radials; so that there is no general dilatation of the gut at the bottom of the cup as in Rhizocrinus, Bathycrinus, and the Pentacrinoid. Some of the Pentacrinidee approach Antedon, while 1 Op. cit., figs. 55-57. REPORT ON THE CRINOIDEA. 91 others rather resemble Rhizocrinus and Bathycrinus in the arrangement of the digestive tube. Pentacrinus decorus is one of the latter. Even at the level of the radial axillaris the gut appears in section as a simple, but spacious cavity, with slight extensions at two points round the connective, or rather calcareous, tissue in which the plexiform gland is embedded. But it could hardly be called kidney-shaped, as it is in Rhizocrinus and Bathycrinus. Some sections of a Pentacrinus disk, that were made for Sir Wyville Thomson by Dr. Stirling, show the indentation of one wall of the gut at the level of the radial axillaries by the plexiform gland and its surroundings to be considerably more marked than in Pentacrinus decorus (Pl. LVI. fig. 4)‘ I am unfortunately unable to determine the species, as the sections were not properly labelled, and the series is not sufficiently complete for the purpose. In Pentacrinus wyville-thomsoni, however, the condition of the gut is much more like that found in Antedon, which it further resembles in its disk being somewhat more inde- pendent of the skeleton than in other Pentacrinidee. Even at the level of the second radials, a horizontal section of the disk shows a strong concavity at one side of the gut, which is thus almost crescentic in outline. The plications of the inner wall, however, are by no means so well developed as they are in many Comatule. In the remarkable genus Actinometra, the radial centre of the water-vascular system does not correspond with that of the dorsal skeleton; and the curious duality of the Crinoid organisation is thus seen more distinctly in this type than in any other. The mouth is not sub-central but excentric, or even marginal (Pl. LXI. fig. 2), and there is no regular symmetry in the distribution of the ambulacra (PI. LV. figs. 1, 2; Pl. LVI. fig. 7). The mouth may be radial, as in all endocyclic Crinoids, and such species of Actinometra as Actinometra solaris, Actinometra pulchella, and Actinometra jukesi (Pl. LY. figs. 1, 2); or it may be interradial, as in Actinometra magnifica (PL LVI. fig. 7); while in some types its exact position is difficult to determine. This is, however, immaterial as regards the course of the digestive tube, which proceeds directly downwards to a point somewhat behind and on the left (east) of the centre of the disk, and then commences to wind. Its direction, just as in the endocyclic Crinoids, follows the watch-hand when seeu from the ventral side; but there are four coils instead of one. This is shown in fig. 3, where the + at the end of the first coil marks the termination of that part of the gut which represents the whole digestive: tube in the endocyclic forms. This first coil occupies the extreme edge of the lowest part of the disk, and consequently passes in front of the mouth, so as to appear beneath it in longitudinal section (Pl. LXI. fig. 2). The second coil passes immediately behind it, and is followed by two more in an ever narrowing but ascending spiral, which terminates in the more or less central anal 1 This figure nearly corresponds to the southeast corner of Pl. VIIb. tig. 7. 92 THE VOYAGE OF H.M.S. CHALLENGER. tube (PL LXI. fig. 1). This is often some little distance in front of the point where the lowest part of the long gullet turns off westwards to enter the great outside coil, The walls of this long digestive tube are tolerably simple and but slightly plicated. For an Fic. 3.—Diagram showing the course of the Digestive Tube in an Actinometra with Interradial Mouth, as seen from the ventral side. Letters as in fig. 2. The + on the hinder portion of the outer coil indicates the limit of that part of the gut which corresponds to the entire digestive tube (excepting the rectum) of an endocyclic Crinoid. extensive secreting surface is amply provided, without the necessity of this further complication,” which is so largely developed in the simple spire of the gut in Promacho- erinus, Antedon eschrichti, and Antedon antarctica. C. THe Water-VascuLaR SYSTEM. The water-vascular system of a Crinoid consists, like that of the Stellerids, of an oral ring and radial vessels, the former being connected indirectly with the exterior through the intervention of the water-tubes, water-pores, and the body-cavity. Neither the oral ring nor the radial vessels have any ampulle connected with them ; though, as suggested by Ludwig," these are perhaps represented by the small lateral pouches of the radial vessels which are opposite to the tentacular branches, and are crossed by muscle-threads? (Pl. LX. fig. 6). The presence of these tentacular branches is invariably correlated with that of the food-groove. Where this is well marked, and lined by ciliated epithelium with the subjacent ambulacral nerve and blood-vessel, the water-vessels beneath the latter give off their branches to the tentacular groups in the usual regular way (Pl. Ve. fig. 7. Pl LVEL. figs, 1) 35.42 PII ies, 1,5 Pi, Tk figs. 1,2, 6—tb; Pl. LXI. figs. 4, 6). 1 Crinoideen, Loc. cit., p. 337. 2 See also fig. 5 on p. 121, m’. REPORT ON THE CRINOIDEA. 93 But if the food-groove on the ventral surface of the arm or pinnule remains undeveloped (Pl. LXI. fig. 3), not only are the ambulacral epithelium, nerve, and blood-vessel absent altogether, but the water-vessels are simple tubes like the integumentary water-vessels of the Molpadide, and have no lateral extensions, as tentacles are absent (fig. 4 on p. 113, w). This condition may occur in a majority of the arms and even on the disk of Actinometra (Pl. LVI. fig. 7); on more or fewer of the lower pinnules of Antedon acoela and Antedon angusticalyx (Pl. LIV. figs. 1-3, 5); and on the proximal pinnules of Antedon eschrichti and Antedon rosacea, which receive no branches from the brachial ambulaecra. In Metaerinus, on the other hand, the ambulacra, and with them the water-vessels, of the large basal pinnules may start directly from the primary. ambulacra of the disk, or even from the peristome itself (Pl. XXXIX. fig. 2; Pl. XLIII. fig. 3; Pl. L. fig. 2). The radial water-vessels which underlie the disk-ambulacra of the Comatule pass off from the angles of the somewhat pentagonal water-vascular ring as single trunks, situated beneath the median lines of the ambulacra. But in Pentacrinus, at any rate in Pentacrinus decorus and Pentacrinus wyville-thomsoni, there is a radial extension of the labial blood- vascular plexus in this position (Pl. LVII. figs. 1, 3, 4, lv); and the two trunks which ultimately unite into the single water-vessel of the ambulacrum are thus kept separate from one another to a considerable distance, 1°5 mm. or more, from the edge of the peristome; that is to say, the angles of the water-vascular ring are produced in the direction of the rays, so that its outline is that of a short-armed Asterias rather than the more regularly pentagonal figure of a Goniaster. The ciliated water-tubes (‘ Steincaniile,” Ludwig) by which the water-vascular system communicates with the body-cavity, and thence with the exterior, vary very greatly in their development. The early Pentacrinoid has but one, situated in the same interradius as the fore-gut. In the later stages of Pentacrinoid life and in the young Comatula just free there are five, one in each interradius; and the same is the case in Rhizocrinus lofotensis. They are multiple in Bathycrinus, though not abundant ; while in the adult Antedon rosacea there are about thirty in each interradius; and in Antedon eschrichti and in Pentacrinus the number becomes still larger (Pl. LVII. figs. 1,3, 4; Pl. LIX. fig. 5—wt). The radial water-vessels of Comatula commence as single trunks arising from the water-vascular ring at the edge of the peristome ; and in a large Comatula like Antedon eschrichti the water-tubes may be found depending from the bases of the radial vessels beneath the middle line of the ambulacrum in the first two or three sections beyond the edge of the peristome. In Pentacrinus, however, the middle line of the commencing ambulacrum is occupied ho 94 THE VOYAGE OF H.M.S. CHALLENGER. by the. blood-vascular plexus (Pl. LVII. figs. 1, 4, U7), which has a water-vascular trunk on each side of it; and the water-tubes extend outwards in a radial direction as long as the water-vessels remain double. This is very evident in some horizontal sections through the upper part of the disk of Pentacrinus naresianus, which were made for Sir Wyville Thomson by Dr. Stirling. The double row of water-tubes may be seen extending along the sides of the ambulacra beneath the line of tentacles, to a distance of 3°5 mm. from the peristome, and then it is not complete. The position of the water-tubes beneath the primary ambulacra is well shown im Pl. LVI. figs. 1, 38, 4. They are seen, as it were, coiling round the subambulacral plates to open below into the upper part of the circumvisceral coelom. When, however, the radial extensions of the labial plexus gradually thin out and the two lateral water- vessels unite into a single median trunk, the water-tubes become less numerous, and are only found in the first two or three sections beyond the point of union. They are thus really in the same position as in the Comatulz, if we consider the double water-vessels as expressing extensions of the angles of the water-vascular rmg in the direction of the rays. The water-pores which pierce the ventral perisome, whether it be plated or not, are in a close functional relation with the water-tubes. They are the openings of minute canals which are lined by columnar epithelium, and expand almost immediately into enlarge- ments where the epithelium is ciliated (Pl. LVIL. figs. 1, 3,4; Pl LIX. figs. 2, 4, 6—wwp). The inner end of the canal beyond the enlargement is lined by pavement epithelium, and opens into the body-cavity. According to Perrier’ the primary water-tubes of the early larval Comatule are directly continuous with the inner ends of the water-pores, without the intervention of the body-cavity. He has not yet figured this connection, however ; and after the careful observations of Ludwig upon the subject, with which my own are in complete accordance, I have considerable hesitation in accepting Perrier’s statements, especially as he admits that the water-pores of mature Comatulz do establish communication between the body-cavity and the exterior, just as described by Ludwig in the Cystid phase. This subject is discussed more fully elsewhere.” [See Appendix, Note D. | In the smaller and simpler types of Crinoids the water-pores correspond in number to the water-tubes. The young Antedon has one in each interradius ; and the same is the case in Rhizocrinus, the single water-pore piercing the oral plate. In Hyocrinus, however, the number of pores is larger. In both the specimens which I have examined there are two pores in the oral plate of the anal interradius, and there are no others in any of the anambulacral plates which lie between it and the edges of the radials. In the other interradii the disposition of the water-pores is as follows :— 1 Sur le développement des Comatules, Comptes rendus, t. xeviii., 1884, pp. 444-446. 2 On some points in the Anatomy of Larval Comatule, Quart. Journ. Micr. Set., N.S., vol. xxiv., 1884, p. 320. ro ro REPORT ON THE CRINOIDEA. 95 Taste [.—Water-pores of Hyocrinus. | Oral Plates. Anambulacral Plates. Interradius. —— ——— as | A | B. A B | No. 11 (anal), . 2 2 0 0 | ree ee 0 | ’ | 2 4 | | | | Cy Sig MS ee 0 | 1 | 3 9 | | | ae th hes 0 | 1 3 7 | | pal, ieee) Saka 1 1 2 7 Thus, therefore, one specimen has all the oral plates perforated by water-pores, with one possible exception ; while in the other it is only in the anal interradius and in the next one to it that the oral plate is pierced by a water-pore. It is significant that this interradius (No. 5) is that in which the primary water-pore appears in larval Asterids, Ophiurids, and Crinoids ; and also that in both the specimens of Hyocrinus the water- pore is situated a little beyond the middle line of the large oral plate (Pl. Ve. fig. 6, wp), just as is the case with the single water-pore of the Pentacrinoid. The disk of Holopus is practically entirely made up of the oral plates, and there is no ventral perisome at all. In the figure of these plates which was drawn for Sir Wyville Thomson by Mr. Black (Pl. III. fig. 2), each plate seems to be pierced by several pores ; but as the specimen was further dissected after being drawn, and the oral plates were not preserved, I have been unable to satisfy myself upon this point. The number of water-pores which may occur in any ordinary Comatula or Pentacrinus varies to a considerable extent. Ludwig estimates that there are 1500 in the ordinary adult Antedon rosacea, and there must be even more in Antedon eschrichti. Except in the immediate neighbourhood of the mouth they are less abundant in the anal interradius than elsewhere ; and though they sometimes occur on the sides of the disk, v.e., over the edge of the ventral surface, they never extend far down towards the dorsal side. When the disk is plated, the pores may be scattered singly in individual plates (Pl. XVII. fig. 6), or they may be grouped together on one plate, sometimes even to the number of twenty, as in Pentacrinus decorus. In the exocylic type Actinometra, the water-pores are generally situated in the immediate neighbourhood of the ambulacra; and the greater part of the disk which is occupied by the large anal interradius is almost entirely free from them. They are not necessarily limited to the disk, for they may also be found on the lower parts of the 1 These numbers correspond to those which are employed by Ludwig in Asterid morphology. 96 THE VOYAGE OF H.M.S. CHALLENGER. arms and also on the proximal pinnules. In both cases they open into that section of the body-cavity which surrounds the generative apparatus, and is known as the genital canal (Pl. LXI. fig. 5). In a few cases too, I have found water-pores on the middle and later pinnules of the arms. They open into the genital canal of the pinnule, close to the point where it arises from that of the arm. D. THe Bioop-Vascunar SystTEM. The foundation of almost all our accurate knowledge of the blood-vascular apparatus of the Crinoids is due to the researches of Ludwig. The blood-vessels form a highly complex system, parts of which are entirely unrepresented in the unstalked Echinoderms (Echinozoa) ; while other parts of it, such as the oral rig and its radial extensions above the water-vessels, conform to the ordinary Echinoderm type. The radial vessels (Pl. VIIa. figs. 4,5; Pl. LIX. figs. 1,5; Pl LX. figs. 1, 4, 6—b) vary considerably in size, and are often invisible if the section be at all oblique. They are large in Antedon eschrichti and in Actinometra nigra, and may frequently be found to contain yellow pigment-masses or coagula. In the latter type they are some- times triangular in section, with the apex pointing downwards so as to be received into a strongly marked concavity in the upper edge of the water-vessel (Pl. LXI. fig. 6) ; but in Antedon eschrichti, Pentacrinus decorus, and in most other types their section is more or less lenticular. Sometimes, however, it is triangular with the apex projecting upwards towards the epithelial layer above, and so rendering the ambulacral nerve much thinner in the middle line than in its more lateral portions (Pl. LX. figs. 1, 6, ). Its cellular lining is much more delicate than that of the intervisceral blood-vessels, and is not easy to make out. Ludwig? found that this radial blood-vessel in the arms of Antedon eschrichti is sometimes divided into two parts by a vertical septum, which has a distinctly cellular covering ; and I have not unfrequently found im the disk of the same species that the lumen of the vessel may be crossed in various directions by delicate threads with nuclei upon them. These resemble the nucleated muscle-threads in the water-vessels, but are much finer and less refractile. The oral ring which connects the radial blood-vessels, and resembles them in structure, extends somewhat beyond the inner edge of the water-vascular ring (Pl. LXIL.); and its wall thus projects into that part of the body-cavity which is contamed within the dense mesh-work of connective tissue supporting the lip (PI. LX. fig. 4, ¢). Ludwig has described in Antedon rosacea a number of more or less branching tubules which are connected with the oral blood-vascular ring, and have a somewhat better defined epithelial lining than the intervisceral blood-vessels.” He thought it possible that they might be in connection with the ramifications of the upper (ventral) end of the plexiform gland, 1 Crinoideen, loc. cit., p. 287. 2 Tbid., p. 328. REPORT ON THE CRINOIDEA. 97 but he was unable to satisfy himself upon this point. The Naples variety of Antedon rosacea, upon which he worked, is about the worst type that could have been chosen for delicate observations of this kind, the quantity and character of the pigment- granules which the lip contains almost totally obscuring the other tissues. This pigment-substance is altogether different from the yellow and brown pigment masses so common in all Echinoderms. It is apparently related to the calcareous spicules which are so abundant in the under part of the perisome and in the intervisceral connective tissue. When these have been removed by acid their outlines are seen to be well defined by streaks of pigment-granules, which appear black by transmitted, ‘and yellowish-white by reflected, light. They are especially abundant in the lip, and in some individuals almost entirely conceal the blood-vaseular plexus which it contains ;! while in specimens from other localities, and in Antedon eschrichti, it is scarcely developed at all, and I have found no difficulty in tracing the connection of the plexiform gland with the oral rmg. This is very evident in all the other Comatule, including Antedon, Actinometra, and Promachocrinus, which I have examined, as well as in Pentacrinus (PE EVI fis: 35Pl, DXi). The branching tubules depending from the oral ring which much resemble the visceral blood-vessels, .open into a dense plexus of more glandular looking tubules that is supported by connective tissue, and extends right round the lip (Pl. LVIL. figs. 1, 3, 4; Pl. LIX. fig. 5; Pl. LX. figs. 1, 2, 4—lp). It is connected with (1) the ventral branches of the plexiform gland (Pl. LVII. fig. 3, av); (2) with the genital vessels of the rays (Pl. LX. figs. 1, 2, gv); and (3) with some of the intervisceral vessels (Pl. LVII. figs. 1, 3, 4; Pl. LX. figs. 2,3, 5,7b; Pl. LXIL). These last form an extensive network over the coiled digestive tube, and are also directly connected with the plexiform gland (Pl. LVII. figs. 2,5; Pl. LVIIL. fig. 6, 7b). This labial plexus is most abundantly developed beneath the south and south-east portions of the peristome, 7.e., in the neighbourhood of the left posterior ambulacrum. It lies between the hind-gut forming the last coil of the digestive tube, and that part of the capacious fore-gut which lies between the two lateral ambulacra of the right side. It is always pretty sharply defined from the surrounding connective tissue, and is usually a some- what prominent object in a well-stained section which is examined with the naked eye ora simple lens. This is partly owing to the relatively thick walls of its component tubules, and partly to the delicacy of the connective tissue holding them together. Its relations are easily made out by the study of series of tranverse and longitudinal sections through the disk. It is not very specially developed beneath the origins of the anterior and antero- lateral ambulacra, the plexiform genital vessels of which may be traced into it; though it is somewhat denser on the left (east) than on the right side, where it is connected 1 [ have found the same equally impracticable pigment in the disk of Actinometra pectinata from Singapore, and also in some individuals of Actinometra parvicirra from Bohol, although others from the same locality are totally devoid of it. (ZOOL, CHALL, EXP,—PART X¥XX11.—1884.) hls 98 THE VOYAGE OF H.M.S. CHALLENGER. below with the plexiform gland rising alongside the fore-gut. But it is very marked indeed in transverse sections behind the mouth (7.e., between it and the anus), as is well shown in the case of Pentacrinus wyville-thomsoni (Pl. LVII. fig. 1, Up), Antedon eschrichti (Pl. LX. fig. 5), or of any Actinometra. It gradually diminishes in size as the distance from the mouth increases, occupying an intermediate position between the two posterior ambulacra. Itis usually rather nearer to the left one (C), but is sometimes closer to the other (D). The genital vessels of these ambulacra are derived from it (Pl. LVIL. fig. 3; Pl. LX. figs. 1, 2—gv), and it finally passes insensibly into the inter- visceral vesssels of the hinder part of the disk. In the specimen of Antedon carinata, one section of which is represented in Pl. LX. fig. 2, the labial plexus lies, as usual, rather nearer the left posterior ambulacrum, continuing very close and compact until just in front of the anal tube, where its meshes open out, and it passes into the ordinary net- work of intervisceral vessels. In like manner the examination of a series of longitudinal sections shows that the labial plexus is denser, and extends farther from the peristome on the left side than it does on the right. In the specimen of Antedon rosacea, a section of which is figured in Pl. LIX. fig. 5, the plexus is much more developed, both anteriorly and posteriorly, at the left edge of the mouth-slit than at the right edge, or even than in the median plane which traverses the anterior ambulacrum. ‘The section figured (Pl. LIX. fig. 5) passes through the left angle of the peristome, from which the two lateral ambulacra diverge ; and the labial plexus is seen as a broad band (/p), which lies between the water-tubes depending from the water-vascular ring (wt), and the fore-gut (fy); it diminishes in size as the distance from the mouth increases, and loses its individuality when the two ambulacra become differentiated. Unfortunately I do not know the locality of this specimen; but it is singularly devoid of the dichroic pigment which so unpleasantly increases the difficulty of accurate observation in the Naples variety of Antedon rosacea. In Promachocrinus kerguelensis, in Antedon eschrichti and its allied species Antedon quadrata and Antedon antarctica, a portion of the labial plexus between the mouth and the anal tube differs very considerably in structure from the rest of this organ. The limits of this portion are so well defined, and it differs so much from the remainder of the labial plexus, that I propose to designate it by the name “spongy organ.” Its relations to the rest of the labial plexus in Antedon eschrichti are shown in Pl. LX. figs. 3, 5, so. The former represents a longitudinal, and the latter a transverse section of it; while in Pl. LIX. fig. 8, a portion of the spongy organ of Promachocrinus kerguelensis is shown more highly magnified. It lies between the mouth and anus on the left or eastern side of the gullet, and therefore is slightly nearer to the left posterior than to the right posterior ambulacrum. In its most fully developed condition, only found between the mouth and anus, the REPORT ON THE CRINOIDEA. 99 spongy organ is a somewhat ege-shaped mass, consisting almost entirely of a delicate net- work of connective tissue with more or less open meshes. The latter are rather wider in Promachocrinus than in any other Crinoid which I have examined. The trabeculee forming its outer portion are much more delicate than those nearer the surface; and I have been unable to make out that they possess any epithelial covering. The surface of the organ, however, is more compact, with larger trabeculae and generally smaller meshes. These are lined by epithelial cells, being in fact the ends of those blood-vessels forming the labial plexus which are connected with the spongy organ, mostly, if not entirely, on its ventral side (Pl. LX. fig. 5). Some of these vessels are seen in more or less oblique section at the right end of the spongy organ of Promachocrinus kerguelensis (Pl. LIX. fig. 8), while the relation of the spongy organ to the labial plexus generally is well shown in the transverse and longi- tudinal sections through the disk of Antedon eschrichti (Pl. LX. figs. 3, 5). The spongy organ of this species is more compact than that of Promachocrinus. It is similarly situated in the space left by the incomplete adhesion of the visceral and parietal layers of the peritoneum ; and it is suspended in this space by threads of connective tissue. It is practically the direct backward continuation of the labial plexus at the eastern angle of the mouth, where it is much more largely developed than on the opposite side. The relatively thick epithelial wall of the vessels gradually disappears as they enter the spongy organ ; while the latter in its turn passes insensibly backwards into the plexus of vessels on the upper surface of the visceral mass, from which are derived both the inter- visceral vessels and the genital vessels of the two posterior ambulacra. The absence of an epithelial lining in the spaces of the spongy organ is very marked, although the epithelium is quite distinct in the blood-vessels which terminate therein. But, on the other hand, I have found, both in this species and in Antedon quadrata, that the nuclei of the connective tissue forming the trabeculee stain very prominently, much more so than I could get them to do in Promachocrinus kerguelensis. Although the simple reticular structure of the spongy organ in this latter type is limited, as described above, to that part of the labial plexus which is situated between the mouth and anus, yet the distinction between it and the remainder of the labial plexus is far less sharp than in Antedon eschrichti. For the vessels forming the labial plexus of this type are much more closely grouped, and have a less definite epithelial wall than is the case in Antedon eschrichti, so that it assumes a decidedly reticular character. This is also the case with the upper end of the plexiform gland, which retains its individuality till quite close to the mouth (Pl. LIX. fig. 9, wv), for it remains large and lobulated, instead of breaking up as in Antedon ; and the connection of its reticular portion with the labial plexus at the north-east angle of the mouth is quite distinct ; while at the western angle the labial plexus, though somewhat reticular in structure, is but poorly developed. 100 THE VOYAGE OF H.M.S. CHALLENGER. Towards the hinder edge of the mouth the trabecular structures in the left division of the labial plexus become more and more delicate, their cellular covering thins out, and the true spongy organ appears, with the characters described above. It is formed almost entirely from the network on the left side of the mouth in which the plexiform gland ends (Pl. LIX. fig. 9, vv). It remains throughout nearer to the left than to the right of the two posterior ambulacra, gradually becoming more compact again, and finally passes into the plexus of intervisceral and genital vessels. The spongy organ of the type which is generally called Antedon rosacea varies very much in its structure. In some cases it is almost as reticular as in Antedon eschrichti, while in others it is hardly differentiated from the rest of the labial plexus, and consists of a mass of twisted tubules, which have well defined epithelial walls. It is possible that these variations may be due to specific differences, but upon this point I can, as yet, offer no opinion. The labial plexus of Pentacrinus, at any rate of the two species which I have studied (Pentacrinus decorus and Pentacrinus wyville-thomsoni), is much more highly developed than in the Comatule, but it contains nothing like the spongy organ of Antedon eschrichti and its allies. It extends outwards for some little distance from the peristome, both beneath and between the ambulacra. In the former case it is connected with the radial blood-vessels, beneath the middle line of the groove, thus keeping apart the converging water-vascular trunks at its sides as already described (Pl. LVIL. figs. 1, 3, 4, 77). Its histological condition in the individuals of both the species which I have examined is not such as to facilitate the observation of minute structural details, but from what I have seen of the better preserved portions of it, I have no reason to think that it differs essentially from the corresponding organ in Antedon. The epithelial lining of its cavities is often fairly distinct, as shown in Pl. LVII. fig. 4. As the ambulacra recede from the peristome and thus diverge more and more, the vascular plexus underlying the interpalmar area which separates them gradually thins out, until it is only represented by the uppermost intervisceral vessels and the genital vessels of the rays, both of which originate init. The former belong to the cireumvisceral layer of the peritoneum, and the latter to the parietal layer ; but the two systems are in free communication with one another (Pl. LVII. fig. 3, gv, ib). The tubules depending from the radial blood-vessel and entering the subambulacral plexus gradually become less and less abundant, and finally disappear altogether, shortly before the limit of the water-tubes is reached. In the anal interradius the labial plexus is specially developed, as is well shown in transverse section in Pentacrinus wyville- thomsoni (Pl. LVII. fig. 1, 7p), lateral extensions of it being connected with the radial blood-vessels by the tubules above mentioned. [See Appendix, Note D.] The subdivision of the upper end of the plexiform gland into numerous branches which terminate in the labial plexus, can generally be made out without any difficulty REPORT ON THE CRINOIDEA. 101 in vertical sections of a disk that is moderately free from pigment. In none of the species of Pentacrinus or Comatula which I have examined, have I failed to observe this connection satisfactorily ; and in some fortunate sections the vascular structure may be traced right down from the oral ring into the lower and more compact portion of the plexiform gland (Pl. LXIL). This is generally more or less lobulated in form, and in this respect very striking differences exist among the various types of Crinoids. Both in Rhizocrinus (Pl. Villa. figs. 7, 8, x), and in Bathycrinus (Pl. VIIb. figs. 1, 4-8, 2) it is almost as simple as in the Pentacrinoid. It is oval-oblong in section and has but slightly developed irregularities of outline. In Antedon rosacea, and in the lower part of the disk of Pentacrinus, until it commences to subdivide, it is more irregular in form (Pl. LVIII. fig. 4, x); and it shows indications of its lobular structure, as is well seen in Ludwig's admirable illustrations ' of the former type. I have made no horizontal sections of the disk of Antedon eschrichti, but imagine that its plexiform gland must be not very unlike that of Promachocrinus kerquelensis. Figs. 5 and 6 on Pl. LVIIL represent horizontal sections through the gland in the lower half of the disk of this type, fig. 6 being that nearer the calyx. The irregularity in the form of the organ is very striking. The upper part of the same disk was cut into vertical sections. They show the extreme subdivision of the ventral end of the plexiform gland, and the termination of its branches in the well defined labial plexus, the spongy part of which is represented in Pl. LIX. fig. 9, xv. The minute structure of the plexiform gland of the Crinoids is as yet unknown. According to Perrier? it is identical with that of the same organ in other Echinoderms. Fresh specimens, and not spirit-material, are absolutely essential for its elucidation ; but as Perrier and Koehler, who have both studied the plexiform gland of the Urchins, give accounts of its structure which differ from one another, and from Apostolidés’ description of the same organ in Ophiurids, there is a difficulty in determing from analogy, and still more so from observation, what its real nature is in Crinoids.*? Certain peculiarities that I have noticed in the appearance of its lower portion in Pentacrinus decorus lead me to think that Koehler’s account of it in the Urchins* is probably more correct than those of his fellow-workers. Upon one point, however, Iam quite satisfied. Although the condition of my material entirely precluded any minute observations on the structure of the plexiform gland, I have had no difficulty in tracing its connection with the intervisceral blood-vessels of the lower part of the disk (Pl. LVIL. fig. 2, Pl. LVI. fig. 6). This point was first noticed by Ludwig in Antedon rosacea, and he illustrated it with an excellent figure.’ I have 1 Crinoideen, loc. cit., Taf. xviii. figs. 57-59. 2 Sur organisation des Crinoides, Comptes rendus, t. xevii., No. 3, p. 18. 3 For a discussion of this subject see Quart. Journ. Mier. Sci., N.S., vols. xxii—xxiv., 1882-1884. 4 Recherches sur les Echinides des Cotes de Provence. Ann. du Mus. d’ Hist. Nat. de Marseille, t. i. pp. 73-77, 95-99. 5 Crinoideen, loc. cit., Taf. xviii. fig. 59. 102 THE VOYAGE OF H.M.S. CHALLENGER. myself described and figured the same connection in Actinometra parvicirra ;* and I have since seen it so frequently in the different species which I have studied, that I read the following statement of Perrier’s with some little surprise. Speaking of the plexiform gland of Antedon rosacea, he says,” “ Les vaisseaux qui paraissent en partir ne sont autre chose que les ramifications de la glande, se terminant d’ordinaire par des ren- flements ayant l’aspect de culs-de-sac. Ces ramifications courent au milieu des innom- brables trabécules du tissue conjonctif de la cavité générale, qui peuvent eux mémes parfois prendre l’apparence des vaisseaux.” I cannot gather from this passage whether Perrier means to deny the existence of intervisceral vessels altogether, or merely the connection of this system with the plexiform gland. I have good reason to believe, as pointed out elsewhere,’ that his statements refer solely to Antedon rosacea ; but even in this unfavourable type I have had no difficulty in confirming Ludwig's observations respecting the relations of this organ to the blood-vessels. If the latter be ramifications of the gland, as Perrier asserts, one would expect that they should have the same structure as it; whereas their nature is the same as that of the intervisceral blood-vessels, which are lined by a layer of pavement-epithelium (PI. LVII. fig. 5); while their apparent blindness is simply due to the impossibility of any single section showing more than a very small portion of their winding course. A careful study of a good dissection, or of a moderately thick transparent section, especially with a binocular, or an accurate plotting out on paper of a series of thin sections by means of a camera, will reveal much that is totally unrecognisable in other ways. [See Appendix, Note E. ] I have studied the intervisceral blood-vessels principally in Von Buch seems to have considered the Blastoids as a third group of equal value with these two. Roemer, on the other hand, degraded the Cystidea and Blastoidea to the level of families or sections of the order Crinoidea, separating off the brachiate forms of the latter as true Crinoidea.* A few years later he proposed to call these by the name “ Actinoidea,” and to rank them together with Blastoids and Cystids as suborders of the Crinoidea.’? This term was thus employed, not in the strict sense of Miller’s original definition, but as co-extensive with the name ‘ Pelmatozoa,” which had been proposed by Leuckart four or five years previously; though Roemer appears to have been unacquainted with it. This was unfortunate, as the use of Leuckart’s excellent name in the Lethaea Geognostica would have avoided much subsequent confusion. In the second volume of Bronn’s “‘Thier-Reich” the Echinoderms aret hrown together with the Ccelenterates into the comprehensive “ Kreis” of Strahlenthiere or Aktinozoa. Four classes of Coelenterates are first considered, and then the Blastoidea and Crinoidea, for which the cumbersome names ‘“ Blastactinota” and ‘‘ Crinactinota” are proposed. Fortunately, however, they have not come into general use. The Cystids are thrown back among the Crinoids, for Bronn did not consider them as differing from the brachiate Crinoids to the same degree as the Blastoids. This was altogether in opposition to the views of Von Buch and Edward Forbes, and also to those of Roemer,’ to whom the peculiarities of the Blastoids and Cystids appeared so marked, ‘‘ dass sie als gleichwerthige, wenn auch nicht gleich umfangreiche Sectionen oder Unterordnungen den achten Crinoiden entgegen zu setzen sind.” Viewed by the light of later knowledge, Bronn’s classification was of a distinctly retrogressive nature. Besides the Cystids he recognised two other divisions of the Crinoidea, viz., the Brachiata or the Crinoidea proper, and the Costata, Miiller, the latter imcluding the problematical Saccosoma. eae The terminology employed by Bronn for the different groups of the stalked Echino- derms is extremely difficult to understand, and appears to contain many errors. Thus on pp. 193 and 421 (op. cit.), the name ‘“ Actinoidea” for the true Crinoids is attributed to Miiller, though it is really Roemer’s, as explained above ; while on pp. 207 and 210 the true Crinoids are referred to as “ Anthodiata,” in contradistinction to the other division 1 Ueber Cystideen, Abhandl. d. k. Akad. d. Wiss. Berlin, 1845, pp. 12, 13, 17, 27. 2 A History of British Starfishes and other Animals of the class Echinodermata, London, 1841, p. xiv. 3 On the Cystidez of the Silurian Rocks of the British Islands, Mem. of the Geological Survey of Great Britain, and of the Museum of Practical Geology, 1848, vol. ii. part 2, pp. 526, 527. * Monographie der fossilen Crinoiden-familie der Blastoideen, und der Gattung Pentatrematites im Besondern, Archiv f. Naturgesch., Jahrg. xvii., Band i. pp. 387, 388. ° Lethaea Geognostica, Bd. i., Theil 2, p. 224. 5 Op. cit., pp. 180, 193. 7 Lethaea Geognostica, Bd. i. Theil 2, p. 224. REPORT ON THE CRINOIDEA. 191 of the “ Crinactinota,” viz., the Cystids. On the other hand, according to the scheme on p. 421, “ Anthodiata” was the name proposed by Burmeister for the Blastoids, while the term “ Brachiata” was also his, and included the true Crinoids and the Cystids. On pp. 8, 227, and 230, however, the term “ Brachiata” is used by Bronn to denote the true Crinoids only, and it is attributed to Miller. Zittel has followed Bronn in this respect, and, as I believe, erroneously. For I have searched Miiller’s writings on Crinoids repeatedly without finding this expression, though frequent reference is made to the “Crinoidea Tessellata mit Armen.” After various unsuccessful attempts to discover where Burmeister’s nomenclature was published, I applied to Prof. F. J. Bell, who was kind enough to make a search in the library of the Zoological Department at the Museum of Natural History, with the following result. In his Zoonomische Briefe, published at Leipzig in 1856 (vol. 1. p. 243), Burmeister gives the following “‘ Systematische Uebersicht der Crinoideen.” I. Crinoidea anthodiata. 1. Cystideen. 2. Blastoideen. Il. Crinoidea brachiata. 3. Tessellaten. 4. Articulaten. 5. Gesippten (Crinoidea costata). 6. Holopus. This classification of Burmeister’s deserved more attention than it has hitherto received ; for it was the first which clearly brought out the difference between the true Crinoids with segmented arms attached to the radials and the “ Anthodiata” or Blastoids and Cystids, in which there are either no arms at all or structures of an entirely different nature from those of the true Crinoids. In this, as in other respects, the Blastoids and Cystids at once differ from the Crinoids and resemble each other. In fact they are so closely linked together that it is extremely difficult to refer forms like Hybocystites and Cystoblastus to one group rather than to the other.’ The term Crinoidea should, I think, be limited to the strictly brachiate forms for which it was proposed by Miller; and it is much less applicable to the stalked Echino- derms generally than Leuckart’s name “ Pelmatozoa.” But except as regards this question of nomenclature Burmeister’s classification agrees far better with our present knowledge than many of those published before or since his time, e.g., that of @Orbigny, Pictet, or of Dujardin and Hupé. Low as the Cystids had fallen in Bronn’s classification from the ordinal position to 1 Quenstedt has solved the difficulty respecting the systematic position of Cystoblastus by describing it twice over. On p. 684 of his “Encriniden” it appears among the Cystids, and is figured on Tab. 113, fig. 89; but on p. 724 it is described as a Blastoid, and it is figured on Tab. 114, fig. 98, under the name of Cycloblastus. 192 THE VOYAGE OF H.M.S. CHALLENGER. which they had been raised by Forbes, they had been, and were subsequently, still further degraded. For d’Orbigny’ took an entirely different view of the characters of the various types of the Pelmatozoa from those held by some of his predecessors ; and he not only threw the Cystids and Blastoids back among the Crinoids, but he considered these two groups merely as families. He divided the order Crinoidea into twelve families, among which are the Comatulidze, Pentremitidee, Cystidee, and lastly the Pentacrinide ; and Pictet” subsequently reduced this number to nine, but without making any change in the four above mentioned. Dujardin and Hupé” also adopted this singular arrangement, according to which the differences between a Pentacrinus and a Pentrenutes, Echinospherites or Actinocrinus, are of no greater systematic value than those between Pentacrinus and Comatula. In this country, however, thanks mainly to the teaching of Prof. Huxley,* Crinoids, Cystids, and Blastoids have always been regarded as independent but equivalent divisions, formerly orders, but now classes of the Echinodermata. To these Huxley’ has since added another, as to the necessity for which there has been a considerable difference of opinion, viz., the Edriasterida. This group, which includes the curious sessile forms dAgelacrinus, Edrioaster, and their allies, has been generally placed among the Cystids ; but it has been re-established quite lately under the name of Agelacrinoidea by 8. A. Miller, in ignorance of Prof. Huxley’s classification of fifteen years ago. I am inclined to think myself that if these forms be anything more than the isolated disks of Palaeocrinoids, as was thought possible by Sir Wyville Thomson (ante, p. 85), their proper place is among the Cystids. Two other new orders (i.e., classes) of the class (¢.e., subkingdom) Echinodermata have recently been proposed by 8. A. Miller.” These are the Lichenocrmoidea and the Myelodactyloidea. But I cannot regard them as of equal value with the Crinoids, Cystids, and Blastoids. Our knowledge of the structure of Iichenocrinus is of the most limited character ; and it is therefore totally insufficient for the basis of a class definition. The same may be said of Cyclocystoides, which together with the so-called Myelodactylus is placed by Miller in a new order that he proposes to call Myelodactyloidea. Whatever be the nature of Cyclocystoides, there can, I think, be little doubt that Salter, Charlesworth, and more recently Nicholson and Etheridge’ were right in regarding the 1 Cours élémentaire de Paléontologie et de Géologie stratigraphique, Paris, 1852, t. ii. fase. i. p. 134. 2 Traite de Paléontologie, t. iv. p. 282. 3 Histoire Naturelle des Zoophytes, Echinodermes, Paris, 1862, yp. 55-58, 4 Lectures on General Natural History, Medical Times and Gazette, November 1856, p. 463. 5 An Introduction to the Classification of Animals, London, 1869, p. 130, 6 Description of three New Orders and four New Families, in the class Echinodermata, and eight New Species from the Silurian and Devonian Formations, Jowrn. Cineinn. Soc. Nat. Hist., vol. v. pp. 221-223. 7 A Monograph of the Silurian Fossils of the Girvan District in Ayrshire, Edinburgh, 1880, pp. 330-334. REPORT ON THE CRINOIDEA. ils} supposed arms and pinnules which were described by Hall as Myelodactylus* as a coiled up stem of peculiar structure. It may perhaps belong to some Crinoid of which the head is not yet known; but until Salter’s statements” have been satisfactorily refuted by Hall or Miller, I cannot admit the Myelodactyloidea as a class of Echinoderms equivalent to the Crinoidea, Ophiuroidea, or Blastoidea. The Echinoderms which have no tube-feet in their ambulacra, and are more or less permanently attached by their aboral surface, seem to me therefore to fall very naturally into three classes, Crinoidea, Cystidea, and Blastoidea. They have several characters in common which sharply distinguish them from the other Echinoderms, and serve to define the branch or division Prtmarozoa, Leuckart, which is of course synonymous with Crinoidea in the widest sense. I am indebted to my friend Prof. F. Jeffrey Bell for the reference to Leuckart’s original definition of the group. I heard the name first from Sir Wyville Thomson, who was greatly struck with its appropriateness, and introduced it into the syllabus of his class lectures. He could, however, give me no reference to it; but Prof. Bell was fortunately able to find it in Leuckart’s Bericht iiber die wissenschaftlichen Leistungen in der Naturgeschichte der niederen Thiere for 1864-65, where the Echinoderms are divided into Pelmatozoa, Echinozoa, and Scytodermata (Holothurians). Working back from this year Prof. Bell eventually succeeded in tracing back this classification of Leuckart’s to a morphological essay published in 1848, where, however, the familiar name Actinozoa is used to denote the Urchins and Starfishes together. After alluding to the essential characters of the Pelmatozoa, z.e., the presence of a stem either temporarily or permanently, Leuckart referred to the two orders of this class, the Cystids and the true Crinoids.? The latter is distinguished by the fact that “‘ An dem obern peripherischen Rande des Kelches noch besondere zahlreich gegliederte Arme sich vorfinden, deren Skeletstiicke immer dem Perisom angeh6ren und stets von dem dorsalen Pole ihren Ursprung nehmen.” In this description of the Crinoids, as well as in the prominence given to the presence or absence of a stalk in the morphology of the Echinoderms, Leuckart seems to me to have been peculiarly fortunate. The only point to which one might be disposed to take exception, and it is in reality more a verbal one than anything else, is his description of the arm-skeleton as belonging to the perisome; for the term “ perisomatic” skeleton is now somewhat limited in its meaning (ante, p. 73). The Pelmatozoa therefore differ altogether from other Echinoderms in the presence of a stem, and in the consequent departure from the ordinary habits of an Urchin, Star- fish, or Holothurian. Whether sessile, or provided with a stem, the Crinoid les on its aboral surface, instead of creeping about mouth downwards in search of food. The lateral 1 Paleontology of New York, 1852, vol. ii. p. 191, pl. xlii. figs. 5, 6. 2 Catalog. Camb. Silur. Foss. Woodw. Mus., Cambridge, p. 118. 3 Ueber die Morphologie und die Verwandtschaftsverhaltnisse der wirbellosen Thiere, Braunschweig, 1848, p. 42. (ZOOL, CHALL. EXP.---PART XXX1I.—1884.) Ti 25 194 THE VOYAGE OF H.M.S. CHALLENGER, branches of the water-vessels are therefore either absent altogether as in the Blastoids and in some of the arms in many Actinometre ; or they supply delicate papillate tubules, the tentacles, the chief functions of which are probably those of respiration and sensation. Ludwig’s researches have demonstrated that the primary water-pore of the Antedon-larva is homologous with the commencing madreporite of an Echinozoon. But inno Starfish or Urchin is the communication between the water-vascular system and the exterior effected through the intervention of the body-cavity as it is in the adult forms of recent Crinoids, whatever be the condition of the larva. There is good reason to believe that the hydrospires of the Blastoids and Cystids were neither connected with the water- vascular ring nor with the body-cavity, so that the absence of a continuous madreporic canal may be regarded as eminently characteristic of the Pelmatozoa, though it occurs in some Holothurians and possibly also in certain Ophiurids. The limitation of the functions of the water-vascular system in the Pelmatozoa, although a natural consequence of the presence of the stem, is in no way connected with this organ morphologically. With the blood-vascular and nervous systems, however, the case is different. There can be little doubt that the remarkable neuro-vascular axis which occupies the central canal of the stem of a Neocrinoid, occupied a similar position in the Palo- crinoids. Even in the case of sessile forms like Hdriocrinus there must have been a chambered organ, from the fibrillar envelope of which were derived the axial cords of the rays and arms, just as in the recent Holopus. The Blastoids all have basal and radial plates, and, with the exception of the Astrocrinide, a perforated stem, so that one can hardly be going too far im assuming that its central canal lodged a neuro-vascular axis, as in recent Crinoids. The same is probably true of the pedunculate Cystids; though I much doubt whether the Agelacrinidee had a chambered organ. This peculiar structure, which is so important a part both of the blood-vascular and of the nervous systems, is essentially anti-ambulacral, being developed in the right larval antimer. With its connections it is as important a part of the organisation of a Pelmatozoon as the cerebro- spinal axis is in a vertebrate animal; and there is in many respects a striking analogy between the two. Although in such intimate relation with the basal and radial plates, the chambered organ cannot be correlated with their presence ; for true homologues of these plates occur in the Echinozoa, in none of which have any traces of an aboral neuro-vascular centre yet been discovered. There are two characters, however, by which some or all of the Pelmatozoa are especially distinguished, viz., (1) the presence of a stem, and (2) the development of arms upon the primary radials, with muscular articulations between their component joints. The majority of the Pelmatozoa have both stem and arms, but the Astrocrinide seem to have had neither, though possibly stalked when young; while the remaining Blastoids REPORT ON THE CRINOIDEA. 195 and the Cystids had no such arms, and the Holopodide and Hdriocrinus were stemless. None of the typical Pelmatozoa, however, are devoid of both stem and arms, with one or both of which the chambered organ seems to be correlated. A so-called pedunculate Starfish has already been described by Prof. Perrier,’ and it was with much disappoint- ment that I learnt from Mr. Sladen’ that Caulaster is far from being the interesting type which it was at first supposed to be. Iam not without hopes, however, that future morphological work upon Urchins and Starfishes may throw more light upon this question ; and there is very much to be done by those who will go into the study of the Paleozoic Starfishes equipped with a knowledge of the morphology of recent Echinoderms, and will not be content with merely compiling empirical descriptions of new species. Miiller’s original classification of the true or brachiate Crinoids divided them into three groups, Articulata, Tessellata, and Costata, the last including the problematical genus Saccosoma, which may perhaps eventually turn out to be an Ophiurid. Reference has already been made (ante, pp. 145-147) to the unsuitability of the Miillerian names Articulata and Tessellata for the two other principal divisions of the brachiate Crinoids. The latter is practically co-extensive with the Paleocrinoidea of Messrs. Wachsmuth and Springer.’ These authors have gone further than Zittel and de Loriol, and have pro- posed to divide up the Crinoidea (understood in the widest sense) into the following orders :—(1) Blastoidea; (2) Cystoidea; (3) Paleeocrinoidea; (4) Stomatocrinoidea ; (5 2) Costata. This classification, however, has been by no means generally accepted. Different as are many of the Paleocrinoids, e.g., Hucalyptocrinus, from a Pentacrinite, others, such as the Ichthyocrinidz, have many of the characters of a recent Crinoid ; and an arrangement which elevates the difference between Pentacrinus and Ichthyocrinus to the same importance as those between Pentacrinus, Pentremites, and Echinospherites respectively, appears to me to be founded on a misconception of the value of morpho- logical characters. On the other hand, although the definition of the Paleeocrinoidea which has been given by Wachsmuth and Springer is capable of improvement in one or two respects, it is far more correct and is based upon sounder morphological principles than any definitions of the Tessellata which have been drawn up by Miiller and his followers. But I cannot regard the two groups Paleocrinoidea and Stomatocrinoidea (Articulata or Neocrinoidea) as equivalent to the Blastoids and Cystids ; so that while keeping the Paleeocrinoids at the level of an order, I should rank the Blastoidea and Cystidea as classes, in accordance with the practice generally adopted in this country. Prof. Chapman* has proposed a classification of the brachiate Crinoids which “is 1 Sur une Astérie des grandes profondeurs de l’Atlantique, pourvue d’un pédoncule dorsal, Comptes rendus, t. xcv. pp. 1879-1381. 2 The Asteroidea of H.M.S. Challenger Expedition, part ii., Jowrn. Linn. Soc. Lond. (Zool.), vol. xvii. p. 217. 3 Revision, part ii. p. 3. 4 A Classification of Crinoids, Trans. Roy. Soc. Canada, vol. i., 1888. Section iv., 1882, pp. 113-116. 196 THE VOYAGE OF H.M.S. CHALLENGER. based essentially on the presence or absence of a canaliculated structure in the calyx and arm plates.” The last of his three leading divisions, the Canaliculata, corresponds to the Articulata, Miiller ; but Chapman’s name does not appear to me to be so greatly superior to Miller’s that it could be adopted without hesitation. Platycrinus, Marsupites, and Uintacrinus have perforated first radials. They are, however, placed by Chapman among the Emedullata, in which “the calyx plates are without internal canals.” The absence of canals in the calyx plates is a character of very general occurrence among the Palzeocrinoids, and one which does not present itself in any adult Neocrinoid. But there are several Paleeocrinoids in which it does not occur at all, and it cannot there- fore be used as the principal “ differentia” for separating the older (Tessellate) from the younger (Articulate) Crinoids. Reasons have already been given for preferring the name “Neocrinoidea” for the latter group to either Stomatocrinoidea or Articulata. The second of these names is certainly founded upon a misconception, and I believe the same to be the case with the first one; while neither of them was ever properly defined by its author. The name Neocrinoidea is coming gradually into use; and as the essential differences between this order and that of the Palzeocrinoidea have already been discussed in Chapter X., it is not necessary for me to go into them again, though they may be conveniently put in the form of a definition. Order NEOCRINOIDEA. Crinoids with a regularly pentamerous calyx, which is generally without primary interradial plates, and except in one genus has no anal or azygous side. The calyx- radials are perforated, and are generally united to the succeeding plates by a muscular ‘ articulation. The rays may remain simple, or divide from one to eight times, the first axillary being usually the second joint after the primary radials of the calyx. Orocentral plate probably never developed ;. orals, when present, may be limited to larval existence, or remain through life partially covering the peristome, but capable of being separated so as to open the mouth to the exterior. The oral surface of the visceral mass, with the ambulacra traversing it, may be more or less paved by plates, but is not in any way covered up and shut off from the exterior by a vault. REPORT ON THE CRINOIDEA. 197 XII.—DESCRIPTION OF THE SPECIMENS. Class CRINOIDEA. Order NEocRINOIDEA. Family Hotorip®, Roemer, 1856 ; emend. Zittel, 1879, and P. H. Carpenter, 1884. Genus, Holopus, dOrbigny, 1837 ; emend. P. H. Carpenter, 1884. A. GeneraL Account oF THE TYPE. Definition.—Basals and radials completely anchylosed into an asymmetrical tube- like calyx, which is fixed by an irregularly expanded base. On the upper edge of the cup are five unequal articular surfaces for the attachment of the second radials. Arms ten, massive, and closely inrolled. Disk relatively small, with a central mouth pro- tected by five oral plates, between which and the edge of the cup is a very narrow irregular pavement of smaller plates. Anus probably present, but not yet observed. Remarks.—The description of this genus, which was established by d’Orbigny in 1837, attracted much attention on account both of the novelty and of the rarity of this singular type. The specimen described by d Orbigny? which was for a long time unique, was brought from Martinique by M. Sander Rang. It is tetra- instead of penta-radiate as most Crinoids are, and this seems to have caused some misconception respecting its true nature, for it receives no mention whatever in Pictet’s Paléontologie; while Dujardin and Hupé* expressed their opinion in 1862 that Holopus is not a Crinoid at all, but an altogether different type, probably a Cirripede.* A few years later, however, a normal pentaradiate example was brought up on a fisherman’s line from deep water off Barbados. It was fortunately acquired by the governor, Sir Rawson Rawson, and was placed by him in the hands of Prof. Louis Agassiz during the stay of the “ Hassler” at Barbados in 1872. Prof. Agassiz intended to have published a full description of the specimen, but was prevented from doing so by failing health, and after his death the figures which he had prepared were published by Mr. Alexander Agassiz, together with a short descriptive note by Count Pourtalés.’ 1 Mémoire sur une seconde esptce vivante de la famille des Crinoides ou Encrines, servant de type au nouveau genre Holope (Holopus), Guérin, Mag. de Zool., Tme année, Classe x., § pp., pl. 8, Paris, 1837. 2 Op. cit., p. 218. 3 Description of a Specimen of Holopus rangii from Barbados, Mem. Mus. Comp. Zodl., vol. iv. No. 8, p. 51. . 198 THE VOYAGE OF H.M.S. CHALLENGER. This specimen was subsequently entrusted by Sir Rawson Rawson to Sir Wyville Thomson, together with two others which he had obtained in 1876, after the publication of Pourtalés’ notice of the first one. Sir Wyville described the three as follows :* “One is very complete in all important points, wanting only the two ‘bivial’ arms, but retain- ing the mouth-valves. The second is a little larger; it wants the mouth-valves, and again the bivial arms; and with Sir Rawson Rawson’s sanction I boiled this specimen down to figure and describe the separate parts. The third specimen is quite perfect, the arms closely curled in in their normal position when contracted; but it is very young, only about 8 mm. in height. Besides the four examples mentioned, I am aware of only another which I have not yet seen; it was shown at the Philadelphia Exhibition, and was afterwards bought by the Museum of Comparative Zoology at Cambridge, Mass.” The second of these seems to have been the original specimen described by Pourtales, from which the oral plates or mouth-valves had dropped away; and as it was gradually fallmg to pieces from natural decay, Sir Rawson Rawson allowed it to be dissected. The figures on Pl. III., with the exception of fig. 2, and figs. 1-4 on Pl. V., show the results of this process, Fig. 2 on Pl. II. is a slightly idealised view of the interior of the cup, so as to show the oral plates of the large specimen represented in Pl. II.’ This was supposed by Mr. Murray to belong to Sir Rawson Rawson, and as it corresponds to No. 1 of Sir Wyville’s list, I quite imagined this to be the case; but Sir Rawson Rawson does not recognise it as his, and I conclude therefore that it is the mutilated dry specimen which Prof. Agassiz informs me was sent by him to Sir Wyville with permission to ‘cut it up for details. In like manner Sir Rawson Rawson thinks it possible that the original of Pl. IV. may be his young specimen mentioned by Sir Wyville as only about 8 mm. in height, but as Prof. Agassiz tells me that he also sent Sir Wyville a small individual, I fear that two specimens have somehow been mislaid. The one which was shown at the Philadelphia Exhibition, and subsequently bought by the Museum of Comparative Zodlogy, is the original of Pl. I. It was obtained by Mr. Wilderboer, the collector for Sir Rawson Rawson, after the latter gentleman had left Barbados, and having come into the hands of Prof. Agassiz, it was sent by him to Sir Wyville Thomson, together with the Holopus material obtained during the dredging expeditions of the “Blake.” This consisted of (1) the very young individual shown in Pl. V. figs. 9, 10; Cruise of 1877-78; Station 22, 100 fathoms ; off Bahia Honda, lat. 23° 1’ N., long. 83° 14’ W.; temperature 71° F. (2) The single ray shown in Pl. Vb. fig. 4. This was preserved in spirit, and the greater part of it was subsequently cut into sections. Cruise of 1878-79; Station 157, off Montserrat, 120 fathoms. 1 On the Structure and Relations of the genus Holopus, Proc. Roy. Soc. Edin., 1877, p. 407. 2 I did not find this out until too late to alter the notice of the oral plates of Holopus, which appears on p. 95. See p. 208. Ges | REPORT ON THE CRINOIDEA. 199 Holopus rangi, VOrbigny (Pls. L-Vb.; Pl. Ve. figs. 1-3). Dimensions. A. (Pl. 1.) B. (PI. IV.) Total height, . 5 : z ¢ ; - 40:00 mm. 8:50 mm. Greatest height of cup on trivial side, : : LosOORy,, 4:25 ,, Least height on bivial side, . : : 5 . 525 ,, G75) Fp Greatest diameter of upper edge of calyx, F : 5 W508) 4p 5:00 ,, Greatest width of trivial axillary (composite), 2 5 Ar) oa 310) 55 Greatest width of arm, , F s 3 5 | URRD a 2:00); Diameter of smallest specimen (Pl. V,) é : 2 oedN GS; Height of smallest specimen, . : : ¢ - 1:00 The tubular calyx which is attached by an irregular encrusting calcareous expansion of variable extent, is thick walled, inversely conical, and slightly bent to one side (Pls. I., I1., [V.; Pl. III. fig. 1). A more or less distinctly marked constriction separates the spreading base from the actual cup, the greatest height of which, measured on the convex side, is 15 mm. Its cavity narrows very rapidly from above downwards, so that the thickness of its walls, which is everywhere considerable, is greatest at its lower extremity (PI. V. figs. 1-4); and it is probable that the cup is completely closed below by the spreading base, if not some little way above it. The analogy of other Crinoids leads one to believe that the cup is composed of radial plates above, and of basals below; but it is difficult to define the limits of either. The radials, however, may be traced downwards some little way, owing to the differences of texture in the limestone network. Sections were made for Sir Wyville Thomson of the least perfect of Sir Rawson Rawson’s specimens. The articular faces round the upper edge of the calyx are shown in Pl. V. fig. 1 (compare also Pl. III. figs. 1, 2). They were described as follows by Sir Wyville Thomson \— “ Each facet is traversed by a transverse articulating ridge, a little in front of which there is the mouth of the tube which lodges the sarcode axis of the joints, and a little behind its centre there is a somewhat longer aperture which appears to lead into the cancellated structure of the outer part of the wall. There are two large shallow muscular impressions on the surface of the facet on the proximal aspect of the transverse ridge.” The larger of these two apertures is not the opening of a canal, like the smaller and inner one; but it leads into a deep pit which lodges the dorsal ligament connecting the radials with the joints above them. It reappears upon the proximal faces of these joints, and upon the articular surfaces of all the arm-joints (PI. III. figs. 3-15). In most Crinoids this pit is merely the deepest part of a large fossa lodging the dorsal ligament (Pl. VIIa. fig. 15, dd’. Pl. VIIb. fig. 5; Pl. Villa. fig. 7—ld; Pl. X. fig. 4; Pl. XX. fig 7); and there is an approach to this condition in the later arm-joints of Holopus, which have a large portion of the articular 1 Proc, Roy. Soc. Edin., 1876-77, p. 407. 200 THE VOYAGE OF H.M.S. CHALLENGER. face on the dorsal side of the pit (Pl. III. figs. 14, 15). But on the lower arm-joints and on the radials there is practically nothing of this kind, and the pit hes immediately next to the dorsal edge of the articular face. But the dorsal surface of the joint is strongly convex and produced far below this edge, as is well shown in PI. III. figs. 5-18. This is also the case with the distal portions of the first radials, as may be learnt from a comparison of figs 1 and 2 on Pl. V. The latter represents a horizontal section of the radials which passes 2 mm. below their edge on the concave (bivial) side, and 7°5 mm. below it on the convex (trivial) side. Around the opening of the central funnel, which is narrower than at the top of the calyx, is an irregularly shaped pentagonal figure. This is formed by the lines of the transverse articular ridges, which in Holopus, as in all other Crinoids, are formed of a much closer and denser limestone reticulation than the remainder of the skeleton. Immediately within these lines are the indications of the small openings of the central canals of the radials; and just outside them are the ends of the pits lodging the dorsal ligaments. The texture of the limestone network forming the inner faces of the radials and the fossee for the attachment of the muscles and the interarticular ligaments is remarkably different from that of the outer portion of the cup. The two are separated by the lines of the transverse articular ridge, as is shown in fig. 2 on Pl. V. and more distinctly in fig. 7, where the dark line indicates the position of the articular ridge. The substance of the radials inside this line is formed of an irregularly open network, the meshes of which reach 0°08 or 0°09 mm. in diameter, though many of them are much less, sometimes not a quarter that width. The peripheral portion of the cup, however, is formed of a much more regular net- work. ‘This consists of concentric and radiating rods which enclose circular or elliptical meshes from 0°015 to 0°035 mm. in diameter, and disposed im regular rows with their long axes tangential. Here and there, as shown in PI. V. fig. 7, the lines of the meshwork are a little irregular, but its general character is very uniform. The difference between the two types of network is most marked, as much in the regularity as in the size of the meshes, as is well shown in the inner and outer portions of fig. 7, and also in the enlarged portions of limited areas which are represented in figs. 5 and 6. Fig. 8, on the same plate, is an ideal diagram, constructed by Mr. Black, showing the regular disposi- tion of this peripheral reticulation. The difference of the two textures is obvious enough to the naked eye; but it becomes more apparent with the help of a lens which brings out the regularly striated aspect of the outer part of the cup. This is well shown in Pl. VY. fig. 2, and less clearly in fig. 4, which represents a section taken about 5 mm. above the basal expansion, and corresponding to the upper face of the vertical section shown in fig. 3. The central funnel is here much narrowed, and the lines of the articular ridges are seen at a distance of about 1 mm. from its opening. Outside the pentagonal figure REPORT ON THE CRINOIDEA. 201 bounded by these lines, the whole of the skeleton is formed by the regular, small-meshed network ; while the inner, less dense portion which has a whiter look, narrows gradually downwards as shown in fig. 3, until it entirely disappears from the wall of the diminish- ing central funnel. There is no trace of it round the greatly reduced opening on the under surface of the segment of the cup which is represented in figs. 3 and 4. In this specimen, as in that represented in Pl. I. and also in d’Orbigny’s original, the lowest portion of the calyx-tube immediately above the spreading base, is partially covered with a chitinous-looking layer of variable height, and marked by roughly concentric lines which somewhat obscure the calcareous network beneath. It is merely a thin superficial skin, however, and is evidently of no special importance, or it would be universally present. The pentagonal figure indicating the position of the articular ridges on the radials is still visible in the section shown in fig. 4, which corresponds to the upper surface of the fragment represented in fig. 3; and the openings of the central canals are also traceable. This would indicate that the greater part of the calyx-tube is composed of elongated radials. One of these canals is seen in nearly longitudinal section in the portion of the lower half of the cup which has been removed to expose the view given in fig. 3. But it is not traceable beyond the limit of the whiter, less dense portion of the skeleton. I strongly suspect, therefore, that this indicates the position of the lower surface of the radials ; and the analogy of all other Crimoids would lead to the conclusion that the small portion of the calyx-tube between this and the spreading base consists of closely anchylosed basal plates, the presence of which was taken for granted by Sir Wyville Thomson." There must certainly be a chambered organ, from the fibrillar envelope of which the axial cords of the rays and arms originate (PI. Ve. fig. 2, A); and one would naturally expect it to be situated at the lowest part of the calyx-tube. This narrows rapidly downwards, and its interior is marked by five vertical ridges corresponding with the radials in position. They are fairly distinct at the level of the section shown in Pl. V. fig. 4; but they become less marked as they proceed downwards, and, being composed of the whiter, less dense network, disappear together with it. They extend upwards to the edge of the cup at the intermuscular notches ; though they are much less distinct on some of the radials than on the others. They thus occupy the position of the ventral radial furrows which are often so marked on the interior of the central funnel of the calyx in other Crinoids (Pl. X. figs. 1, 4, vrf; Pl. XII. fig. 15; Pl. XX. fig. 8; Pl. XXX. fig. 3). From the facts detailed above, we may, I think, assume with tolerable certainty that the tubular body-chamber of Holopus is not composed of a “ piéce centro-dorsale sessile ” as stated by de Loriol;’ but that it consists of basals and radials like the calyx of any other Crinoid. I cannot quite make out whether de Loriol employs the word “centro- 1 Loe. cit., p. 407. 2 Paléont. Frang., loc. cit., p. 188. (ZOOL, OHALL, EXP,—PART Xxx1r.—1884.) li 26 202 THE VOYAGE OF H.M.S. CHALLENGER. dorsal” in the sense in which it is usually understood, 7.e., as the cirrus-bearing top stem- joint of the Comatule. The tubular body-chamber of Holopus is, however, distinctly not of this nature; so that the use of the name “‘ centro-dorsal ” is apt to lead to confusion. In a subsequent passage ' de Loriol expresses another view of the composition of this cup or “cupule.” He speaks of the axillaries which are articulated to its upper edge as “yadiales uniques,” resting as in Cyathidium, “sur les angles de la cupule, qui pourrait done étre evisagée comme étant composée de cing pitces basales interradiales.” This would be a most singular morphological condition, and one without a parallel in any other Crinoid. Primary radials would be in contact with each other, but not united, and rest on articular surfaces each of which would be formed by the upper edges of two basals. The union between basals and radials is invariably a simple synostosis such as I have described above (pp. 2, 3), and never a muscular joint like that between the upper edge of the calyx-tube of Holopus and the compound axillaries. The evidence afforded by sections of the cup, however, indicates clearly that it is principally composed of closely united first radials which, as will be pointed out subsequently, have a remarkable similarity to the radials of the Liassic genus Hudesicrinus. Sir Wyville Thomson thought it probable that second radials are also present in the cup. If so, they must be united to the first by synostosis, which would be a most unusual condition in any Neocrinoid; and the close resemblance of Holopus to Eudesi- crinus seems to negative this idea altogether ; while, as pointed out by Sir Wyville,’ there would be a true muscular joint between the second radials and the radial axillaries, which is not the case in any other recent Crinoid. Considering then the articular surfaces at the edge of the calyx tube as those of first radials, we find that they differ considerably in size. According to Sir Wyville Thomson ’ “‘ the upper border of the cup, bearing the facets, is very irregular in thickness ; and in all the specimens which I have seen, including d’Orbigny’s, one side of the border is much thicker and considerably higher than the other side, and the three arms articu- lated to it are much larger than those articulated to the opposite side. There is thus a very marked division into “bivium” and “trivium,” and consequently a bilateral symmetry underlies the radiated arrangement of the antimeres.” This is shown in Pl. V. fig. 1, and also, though less clearly, in Pl. III. fig. 1. Besides this again the individual facets, both of bivium and trivium, are of different sizes and shapes. The articular ridge which crosses the central facet of the trivium is considerably longer than that of either of the two remaining facets, and these are longer than the ridges on both the bivial facets. The adjacent muscular plates of these two last are fused into a short tongue-shaped process which stands up prominently in the angle of the bivium. It is essentially of the same nature as the “clavicular piece” which projects in the middle of the distal 1 Paléont. Frane., loc. cit., p. 191. 2 Loe. cit., pp. 407, 408. 3 Loc. ctt., p. 408. er ee aN tee et ee oe ee RT a eo rr REPORT ON THE CRINOIDEA. 203 face of every axillary, radial or otherwise (PI. II. fig. 4; Pl. XXI. fig. 1c). A similar but larger process is formed by the fusion of the remaining muscular plate of one of the bivial facets with its fellow on the adjacent facet of the trivium (woodcut, fig. 10). This is seen in the lower part of Pl. V. fig. 1; and it is also visible projecting into the cavity of the calyx in the corre- sponding part of fig. 2. The other projection seen to the west of it in the same figure is formed by the united muscle-plates of two of the trivial facets, which extend inwards in a more horizontal direction than the larger processes already described." These two large projections are also seen in the north-east por- Fic. 10 —View of the upper part of the calyx-tube of Holopus rangi tion of fig. 1 on Pl. II., which likewise shows very clearly the on its lower or bivial side. The A 8s é two bivial facets are well shown, separation of the two bivial facets by a pointed: upward together with the interradial pro- “ ae cess separating them. The left extension of the outer surface of the calyx. This is very hand one is separated from the 4 e a “ adjacent trivial facet by a still evident in Pl. I. fig. 1, and im the right hand figure on larger process ; but there is ouly a small one on the right side. Pl. II. The latter on its left hand side shows traces of the same condition between the other angle of the bivium and the trivial facet next it. This is also visible on the left of Pl. III. fig. 2. But it is much less distinct in the large specimen represented on P]. I. In the young individual shown in PI. IV. this character is fairly well marked, except at the two angles of the trivium ; while in the still younger and very remarkable specimen obtained by the “ Blake” (PI. V. figs. 9, 10), the shallow calyx is much more symmetrical, and its outer surface sends a pointed extension upwards between every two facets. This surface is marked by an irregular row of scattered tubercles, though none are visible in the other young specimen (PI. IV.). They are replaced, however, by tolerably well defined ridges which occupy the middle line of the radials, and extend downwards from their upper border to a little distance from the spreading base. They diminish as they go, and finally disappear altogether at a level which probably marks the downward limit of the radials. They are naturally more distinct on the trivial than on the bivial side, and are better marked on the united second and axillary radials, where they bifurcate and are continued outwards on to the arms as well defined medio-dorsal ridges. The lower joints, especially of the trivial arms, also bear one or two small tubercular elevations on either side of the median ridge. These median ridges like- wise appear on the second and third radials of the youngest specimen, in which, however, they have more the appearance of a partially disconnected line of tubercles (Pl. V. figs. 9,10). A row of ill defined tubercles is also visible immediately inside each lateral edge of the second radials. There is a good deal of difference in the external ornamenta- tion on the calyx-tube of the two adult individuals. The large American specimen 1 Both these figures, as well as the remaining ones on the plate, and in fact all those drawn for Sir Wyville Thomson, are reversed, haying been drawn upon the stone in the natural position of the specimens. Aue Pe Toa a See 204 THE VOYAGE OF H.M.S. CHALLENGER. (Pl. L) is almost bare, though faint elevations are visible along the middle lines of the radials, and indistinct, scattered tubercles appear between them, except in the centre of the trivium. In the smaller specimen, however (PI. II.), there are three, fairly distinct double rows of blunt tubercles which correspond to the trivial radials. But on the bivial side there is more indication of median ridges; while in the fragment shown in woodcut (fig. 10) the double row of tubercles is tolerably distinct all round the cup, except on one of the bivial radials. Other tubercles are scattered about between these rows, though without any definite arrangement; while they are abundant on the dorsal surfaces of the two outer radials and of the large lower arm-joints (PI. III. figs. 3-9), disappear- ing, however, as the joimts become more and more compressed laterally. All the entire specimens of Holopus which are known to science have been preserved in the dry state, and have a blackish-green tint which is due to pentacrinin, as stated above (ante, p. 129). It is darkest in the older individuals, and contributes to the shagreen-like appearance that is so characteristic of the type. An isolated ray (Pl. Va. fig. 3; Pl. Vb. figs. 4, 5) was, however, obtained by the “ Blake ” off Montserrat, and preserved in spirit. In this condition the skeleton has a dead white appearance. In the figure of d’Orbigny’s original specimen the first radials are shown to bear large, pentagonal axillaries which appear to be all in one piece. They were so described by Pourtalés,* and also by Sir Wyville Thomson,? who did not, however, exclude the possibility that they might be formed of the second and third radials coalesced, with the syzygy between them obliterated. The very young individual dredged by the “ Blake,” and the somewhat older form, shown in Pl. IV., throw much light upon this question. The calyx-tube of the former (Pl. V. figs. 9, 10) is wide and shallow, while the second radials which it supports are widely hexagonal and only partially in contact laterally. Resting upon their distal edges are the smaller triangular plates to which I have referred as the axillaries. Agassiz, in his brief description of this remarkable form,’ states that the larger hexagonal plates are “the radial axillaries of Sir Wyville Thomson, but the smaller ‘triangular ones seem to become fused with them in the adult.” I think, however, that there can be little doubt that the larger plates are second radials, and the triangular ones the third or axillary radials. They are all equal and similar, and meet one another all round so as to completely close the cavity of- the calyx. It might be suggested that these are the combined second and axillary radials, while the hexagonal plates are the first radials, and no others are present. I do not think, however, that this can be the case ; partly on account of the very marked manner in which the hexagonal plates are separated from one another and from the shallow cup below them; and partly because there is no indication whatever of their sending upward extensions between the 1 Mem. Mus. Comp. Zodl., vol. iv. No. 8, p. 62, 1878. > Loe. cit., p. 408. 3 Description of a young Holopus, Bull. Mus. Comp. Zoél., vol. v. p. 218, 1879. REPORT ON THE CRINOIDEA. 205 axillaries, like those visible in the next youngest specimen (PI. IV.); whereas the hexa- gonal plates themselves are separated in this manner. Further, in nearly all Neocrinoids which have ten or more arms there are three radials. This is true of all the recent Crinoids except Metaerinus, which has a larger number, four or six; and the only fossil genus which has two radials is the aberrant form Plicatocrinus. In all the Neocrinoids, except de Loriol’s recently established genus Hudesicrinus, there is either a syzygy or a hgamentous articulation between the two outer radials ; and the existence of a syzygy in Holopus is therefore nothing unusual, though there is less evidence of its presence in the adult condition than is usually the case. But this is scarcely surprising when we remember the excessively intimate union of the first radials, of which no indication whatever is visible on the exterior of the calyx. Some individuals, however, exhibit distinct traces of a sutural line dividing the large axillary into two parts. Such a line is visible in the young specimen (PI. IV.) on all the axillaries of the trivium, crossing them at the point where the medio-dorsal ridge bifurcates as described above ;* but it is less distinct in the two bivial axillaries. On the other hand, the three trivial axillaries of the large American specimen present’ no indications whatever of being composite joints, and have a regular; broadly pentagonal shape. This is well shown in Pl. I. fig. 2; but the bivial axillaries represented in fig. 1 are of an entirely different character, each of them being distinctly in two parts, which look as if they were articulated rather than suturally united, while they do not present the symmetrical appearance characteristic of the corresponding parts in other Crinoids. In the one case there is a large and wedge-shaped second radial which has all the appearance of an ordinary brachial. It supports a triangular axillary, but the apposed faces of the two do not: correspond exactly. The axillary extends beyond the narrower end of the second radial, and so comes in contact with the upward extension of the first radial already described. This is shown in Pl. I. fig. 1. The broader end of the second radial, however, extends considerably beyond the axillary, and meets not only the com- posite axillary of the adjacent trivial ray, but also the first brachial of its own ray as well as that of the next. The second radial of the other bivial ray, which is shown in the middle of PI. I. fig. 1, is more oblong than its fellow. Like it, however, it is wider than the roughly triangular axillary, and supports a considerable portion of the large first brachial. But it is not overlapped by the axillary at the other end, and completely cuts it off from the first radial below. None of the four remaining axillaries of the specimen figured in PI. II. show any distinct traces of their being of a composite character ;? though there are some lines upon 1 These lines are not clearly seen in the positions of the specimen which are represented on Pl, IV. 2 The lower angle of one of these exhibits an accidental fracture. 206 THE VOYAGE OF H.M.S. CHALLENGER. one or two of them which may perhaps admit of this interpretation. But not even this can be said of the originals of figs. 3 and 4 on Pl. III. I think, however, that the evidence detailed above is sufficient to bear out the statement that Holopus has three radials, of which the two outer ones are united by syzygy. We should accordingly expect to find a similar syzygial union between the first and second brachials; but of this there is no evidence whatever. The distal face of the first and the proximal face of the second brachial (Pl. III. figs. 3, 7) present the ordinary characters of a muscular joint. There are, indeed, in the small specimen shown in Pl. IV. some traces of lines crossing the first brachials, which might be taken as indicating a syzygial union of two primitive joints ; but they are nothing like as distinct as those in the radials. I think, therefore, that for the present, at any rate, we must regard Holopus as an exception to the general rule which holds good in other Crinoids, as to the similarity between the modes of union of the two outer radials and the two lower brachials respectively (ante, p. 49). It is further remarkable from the fact that there seem to be no syzygies between any of the other arm-joints. The outer surfaces of the composite radial axillaries were described by Sir Wyville Thomson’ as “ very gibbous, thrown ‘out into almost hemispherical projections, studded with low tubercles” (Pl. III. figs. 3-5). They are produced dorsally a considerable distance beyond the edges of the articular faces, as is the case with all the lower arm- joints (Pl. III. figs. 6-13); and they fit very closely against their fellows, their sides being flattened and more or less marked by ridges and furrows, which interlock with those on the adjacent axillaries. These furrows are also apparent on the sides of the lower arm-joints (Pl. II.; Pl. IIL. figs. 6-12; Pl. Va. fig. 3; Pl. Vb. fig. 4). The muscle-plates of the axillaries, and in a less degree also those of the arm-joints, are greatly thickened, and their upper edges are cut out into coarse teeth. ‘This is well shown in the right-hand figure on Pl. II. and in the upper part of Pl. III. fig. 2, where some of the adjacent axillaries are seen interlocking with each other. In all the specimens of Holopus yet known, including the fresh fragment dredged by the “ Blake” off Montserrat, the arms are strongly recurved, and by their close mutual apposition conceal the disk entirely (Pls. I., IL, IV.; Pl. Va. fig. 3; Pl. Vb. figs. 4, 5). Obviously, however, this cannot be the natural condition of the livimg animal. There is a large food-groove on the upper surface of each arm and pinnule (PI. Va. fig. 1; Pl. Vb. figs. 1, 4, 5); and there is every reason to think that the living animal, when undisturbed, spreads out its arms with the ventral surface upwards just as other Crinoids do for the purpose of obtaining food. The large size of the paired flexor muscles uniting the joints (Pl. Vb. fig. 1, m) would seem to give the power of rolling in the arms very rapidly and completely, so as to afford the utmost protection to the soft parts contained within the cup; while the small, but very close and compact bundles of elastic 1 Loc. cit., p. 408. OL REPORT ON THE CRINOIDEA. 207 ligaments on the dorsal side of the articular ridges would help in the extension of the arms again, It has already been mentioned that the trivial arms are larger and better developed than those of the bivium; but im both cases a variable number of the lower joints (Pl. IIL. figs. 6-13) are considerably larger than those which follow them (figs. 14, 15), and the passage from one to the other is usually somewhat sudden. On the trivial arms there are generally from 8 to 10 of these large, massive jomts; but on the bivium there are only about seven, six, or even less. The difference between the two is very well shown in the small specimen represented in Pl. IV. The shape of these lower arm-joints is rather variable. They may be roughly oblong as is the case with the first two or three, or their edges may be more oblique so. as to give them a truncated wedge-like form. The more wedge-shaped these joints are owing to the obliquity of their terminal faces, the greater is the inequality in the size of the muscle-plates on the two sides of the median groove. This inequality is visible in the joints represented in Pl. IIL figs. 10 to 12, though it is sometimes still more distinct. The pinnule-socket of such a joint is on the thickened upper edge of the higher muscle-plate. The general character of these lower arm-joints is much less regular and symmetrical than is the case in other Crinoids, so that many of them are more or less of a monstrous nature. In some few cases, indeed, the joint is smaller than usual and triangular, not extending completely across the arm, so that the joints above and below it come into contact with one another. This is shown in various parts of both figures on Pl. L.; and it is comparable to the condition of other parts of the same specimen, viz., the way in which the first brachials may partly rest on the second radials, or the axillaries on the first radials, as has been already described. Sometimes again, a first brachial becomes unusually large, as is shown on two of the bivial arms in Pl. I. fig. 1. The inner one of the two bears a small, triangular, second brachial, and consequently comes into contact with a similarly large, third brachial along its outer edge; but the outer edge of the other second brachial sends a long process forward by the side of the next three joints, which are much smaller than their fellows of the adjacent arm. Other irrecularities of growth appear in the same individual, but they are by no means so marked in that shown in Pl. II. This, moreover, shows very well the rather sudden diminution in the size of the arm-joints which lose their tubercles and gradually become laterally compressed, so that their medio-dorsal edge is tolerably sharp. This form of joint is figured in Pl. III. fies. 14, 15, and Pl. Ve. fig. 2. The longest arms seem to have about eighteen of them, raising the total number of brachials to between twenty-five and thirty. The larger, outer sides of all the brachials bear the pinnules (Pls. II., Va., Vb.). That of the first brachial is comparatively small, and is attached close to the distal edge of the joint; the next pinnule is invisible in all the specimens, but those of the third 208 THE VOYAGE OF H.M.S8. CHALLENGER. and following brachials are much larger and have broad lower joints that gradually come to take up more and more of the whole surface of the arm-joints to which they are attached. In fact the bases of the pinnules of alternate joints that are borne upon the same side of the arm are only just separated from one another by the narrow ends of the intervening joints, which have their pinnules on the opposite side of the arm. This is well shown in the right-hand figure on Pl. I1., and also in Pl. Va. fig. 3. The pinnules are rolled in upon themselves (PI. III. fig. 16) exactly in the same way that the arms are (PI. Va. figs. 1, 2). The four or five lower joints are very broad, but the rest of the pinnule tapers away rather rapidly. The joints are united by paired muscular bundles (PL Ve. fig. 2, m), which is a somewhat unusual condition. The disk of Holopus is unfortunately still but very imperfectly known, and I have only been able to examine it in one specimen. The central mouth is protected by five large and triangular oral plates which are opposite to the clavicular pieces of the united radials (Pl. III. fig. 2). The lateral edges of each of these plates are thickened and some- . times more or less cut into false teeth ; while the raised central portion is pierced by from fifteen to twenty minute holes, the water-pores. The bases of the orals seem sometimes to rest directly against the edge of the radials; while they are sometimes separated from this edge by an irregular row of small triangular plates. It is not unlikely that an anal tube is concealed somewhere or other among these plates, as in the case of Hyocrinus (Pl. VI. figs. 8, 4); but I have seen no certain traces of it in the dry specimen. The same would probably be the case with Hyocrinus under similar conditions. The food-grooves which come away from the mouth between every two of the oral plates are continued out on to the axillaries and from thence on to the arms. They occupy the deep channel between the large muscular processes at the sides of the joints, and in the dry specimen appear to be bordered by small, irregular plates. These, how- ever, do not seem to correspond either to the side plates or to the covering plates of other Crinoids \(Pl. Vie. figs.9, 10: ePl) Que fies 76/76 PL a, digs’ ai, 6125 Play figs. 4, 6-9); for an examination of spirit specimens shows that these small plates really belong to the tentacles, which are relatively large and stout (PI. Va. figs. 1, 2. Pl. Vb. fig. 2; Pl. Ve. figs. 1-3—T). The bases of these tentacles are protected by scale-like plates formed of the usual calcareous reticulation (Pl. Vb. figs. 2, 3). They are not easily made out at the side of the arm-groove, but on the lower parts of the pinnules there seem to be from two to three tentacles on either side of each joint. It is difficult to get a correct estimate of their absolute size ; but after careful comparison with an eyepiece micrometer I should judge them to be nearly twice the size of the largest that I could find in any preparations of Antedon eschrichti. The general arrangement of the tentacles is the same as in other Crinoids; but the epithelial layer covering them is, if anything, thinner than in Antedon eschricht, though thrown into much stronger corrugations at the outer ends of the tentacles. Py REPORT ON THE CRINOIDEA. 209 Shortly before his death Sir Wyville Thomson placed in my hands a portion of the ray represented in Pl. Vb., with the request that I would cut it into sections for him. I found this to be an exceedingly difficult task, partly because of the rolled-up condition of the arms, and partly because the calcareous substance of the skeleton is so much denser than that of other Crinoids; so that the organic basis which is interpenetrated by it and remains behind after decalcification, has nothing like the consistency that we meet with in the corresponding parts of the Comatule or of Bathycrinus. The presence of large bundles of muscles and ligaments without any helping syzygies also increases the difficulty of all attempts to obtain thin sections. But although I was not so successful as I could have wished, I was able to determine satisfactorily that the anatomy of a Holopus-arm is similar in all essential respects to that of an ordinary Crinoid (Pl. Vb. fig. 1; Pl. Ve. figs. 1, 2). The axial cord traversing the central canal of the skeleton gives off its pinnule branches in the usual way, #.e., alternately on opposite sides. These branches have a long distance to go before they reach the pinnules, owing to the attachment of the latter on the upper edges of the large muscle-plates. As long as the branch remains in the substance of the arm-joint it does not take a straight course as is the case in the other Crinoids, but is thrown into a series of loops in a dorsoventral direction (Pl. Ve. fig. 2, a), and after it enters the pinnule its course is still somewhat sinuous (Pl. Ve. fig. 3, @). These branches, like the main arm-trunk, are relatively of very small size, which is perhaps to be accounted for by the fixed position of the animal. No swimming movements are of course possible, but only those of flexion and extension are performed by the arms. All the ambulacral structures of the Holopus-arm are lodged in the deep median groove of its skeleton, and are usually small in comparison with the great transverse diameter of the joints. The cceliac canal is situated, as usual, between the two large muscular bundles, with a small genital canal separating it from the single subtentacular canal above (PI. Vb. fig. 1). The epithelial lining is very much the same in character in all these canals, consisting of low flattened cells. According to Ludwig? this is also the case in Antedon eschrichti, but this statement is not borne out by his figures. In one figure” he represents a well marked cellular lining to the cceliac canal and subtentacular canal, but leaves the genital canal without any; though in a more magnified representation ® the wall of the genital canal bears an excessively delicate layer of much flattened cells, which consist of little more than nuclei. This is more in accordance with my own observations, for | have always found that the epithelial cells in the genital canal are much flatter and less easy to see than those in the cceliac and subtentacular canals. In Holopus, however, the difference is much less marked. The genital cord is of essentially the same nature as in other Crinoids; though it is of a much less branching character in the axillary radial 1 Crinoiden, loc. cif., p. 29. 2 Thid., pl. xii. fig. 8. 3 Ibid., pl. xiii. fig. 13. (ZOOL. CHALL, EXP.—PART XXx1I,—1884.) Li 27 210 THE VOYAGE OF H.M.S. CHALLENGER. than is usually the case so near the disk. It is connected with ovaries alternately on opposite sides of the arm, from about the first to the fifteenth brachial (Pl. Ve. fig. 1, gc.). The ovaries are short and stout, and confined to the pinnule-bases in the broader, lower parts of the arms; but where the joints are smaller the ovaries appear immediately beneath the water-vessel, and the boundaries between the three arm-canals cannot be traced (Pl. Ve. fig. 2, ov). The ova, of which all stages are visible, are more like those of Antedon eschrichti than is the case in many Comatule, but they are somewhat larger, reaching a diameter of 0°22 mm.; while 0°1737 mm. is the size of the largest ovum of Antedon eschrichti which was measured by Ludwig. I have unfortunately been unable to make out anything definite with regard to the presence of a radial nerve and blood-vessel, which are ordinarily found between the water-vessel and the ciliated epithelium of the food-groove, but thisis so often the case in other Crinoids, except in sections of more than average goodness, that I have no doubt whatever respecting the existence of these structures in Holopus; and I see no good reason to believe that in any essential point of its visceral anatomy there is any important difference between it and other Crinoids. All the specimens of Holopus which have been preserved in the dry state are of a dull dark green tint, sometimes verging on black. But Mr. Agassiz records that on one occasion, off Montserrat, the “ Blake” dredged an imperfect whitish specimen. This consisted of a detached axillary jot and the two arms belonging to it, as shown in Pls. Va. fig. 3, and Vb. fig. 4. The green colour assumed by the dry specimens is possibly due to post-mortem changes, as seems also to be the case in the Pentacrinide. Prof. Moseley informs me that many of the individuals dredged by the Challenger were white when captured, although tinged with pentacrinin, owing to the colouring matter being in some way masked during life, and only manifesting itself after death. During a visit which I paid him recently at Oxford, one of the dry specimens of Holopus was treated with spirit, and yielded a dull green solution with a red fluorescence. Prof. Moseley examined it with the spectroscope, and found the colouring matter to be identical with the pentacrinin which he had discovered in the various species of Pentacrinus and Metacrinus that were dredged by the Challenger in the Pacific and East Indian Archipelago. Holopus has not yet been met with outside the Caribbean Sea. D’Orbigny’s original specimen was obtained at Martinique, while, thanks to St Rawson Rawson, others have been discovered in the neighbourhood of Barbados. The young individual figured in Pl. V. was dredged by the “Blake” in 100 fathoms off Bahia Honda; while the white fragment, already mentioned, was found. at a depth of 120 fathoms off Montserrat. During the stay of the Challenger at Bermuda,’ Sir Wyville Thomson obtained from 1 The Atlantic, vol. i. p. 321, REPORT ON THE CRINOIDEA. 201 a local collector “a small worn and rounded fossil, which seemed to be the cup of a Crinoid allied to Holopus.” Prof. Moseley tells me that he thinks it was a recent specimen in the dry state; but since it has unfortunately been lost, | am unable to say anything as to its nature. B. On tHE Systematic Position oF Ho.oprus. For some time after the publication of d’Orbigny’s original description of Holopus the real nature of this remarkable type was more’ or less misunderstood, partly, perhaps, because the original specimen was tetramerous and not pentamerous like most Crinoids. Eventually, however, Roemer * made the genus the type of a new family, Holopocrinide ; though he did not characterise it more closely. This proceeding was objected to by Quenstedt” partly on account of the imperfection of our knowledge of the type, and partly because he considered it possible that Holopus might be merely a larval form, destined eventually to become detached and to undergo further transformations. He added ‘‘ Die Kiirze der Siule, die keilf6rmigen Armeglieder mit einfachen Pinnulen sprechen an meisten fiir die Comatulafamilie.” The latter character, however, is absolutely worthless as a generic distinction, many Comatulz having discoidal or saucer-shaped arm- joints like those of Pentacrinus and Apiocrinus, while all the Neocrinoids have simple pinnules. The first peculiarity mentioned by Quenstedt is founded on a misapprehension, for he considered the calyx to be formed of the axillary radials only, regarding the tube- like body-chamber as a stem. It exhibits no transverse segmentation, however, and has five articular facets on its upper edge, while it encloses the viscera ; and all these characters are totally foreign to the stem of a larval Crinoid, or indeed of any Crinoid whatever. In the year 1847 a remarkable new type of fossil Crinoid was described under the name of Cyathidium by Steenstrup,’ who spoke of it as like Hugeniacrinus, but without a stem. In Theil u1. of the Lethzea Geognostica, Roemer made it the type of a separate family Cyathidiocrinidz, which he placed next to the Holopocrinide ; but in Theil v. he refers to it as belonging to the Poteriocrinide, together with Eugeniacrinus and Taxocrinus. Between Holopus and Steenstrup’s Cyathidiwm from the Faxoe Chalk there is certainly a very close analogy, though there are a few well marked differences. Apart from the bud-like peculiarities of growth presented by Cyathidiwm, it has a more open cup, with relatively thinner walls than that of Holopus, Its appearance varies consider- ably in different individuals, being sometimes low and shallow, and in other cases longer and more tapering. The articular facets on its upper edge are much smaller than in Holopus, and their downward slope faces inwards instead of outwards, as in the recent form (PI. III. fig. 1), 1 Lethza Geognostica, Theil. ii. pp. 226, 227. * Encriniden, p. 186. 3 Amt. Bericht w. d. 24 Versamml. deutsch. Naturf. und Aerzte in Kiel, 1846, published 1847, p. 15. 212 THE VOYAGE OF H.M.S. CHALLENGER. In fact the articular ridge and not the edges of the muscle-plates forms the immediate boundary of the central cavity; and the fossa for the dorsal ligament is still more reduced than in Holopus, where it is represented by a median pit that is scarcely to be traced at all in Cyathidium. The presence of these articular faces seems to have escaped the notice of de Loriol, which is doubtless due to his not having been able to examine sufficiently good specimens. For he describes the calyx of Cyathidium* as composed “dune piéce centro-dorsale cupuliforme portant, sur son bord supérieur, cing facettes syzygales, sur lesquels reposaient, sans doute, des piéces radiales dont le nombre est inconnu.” These supposed syzygial facets are, however, the articular faces of first radials, which are by no means so unknown as de Loriol supposes, though their inferior boundary is still uncertain. The imner face of each side of the more or less pentagonal cup formed by these radials is marked by a median furrow corresponding to the ventral radial furrow of other Crinoids (Pl. X. figs. 1, 4, orf; Pl. XX. fig. 8), and immediately external to its upper end is the opening of the central canal. These features indicate that in Steenstrup’s Cyathidium the sides of the pentagonal cup correspond to the radials, just as they do in Holopus (Pl. V. figs. 1, 2, 4). To this same genus Cyathidium, Schliiter has doubtfully referred a minute Crinoidal calyx discovered by him in the Eocene of Monte Spilecco near Venice.” It only reaches 9 mm. in height, but has the same general form as the cup of the recent Holopus, being attached by a spreading base, between which and the cup proper there is a more or less well marked constriction. This does not appear to be generally the case in the Faxoe specimens. In one or two cases there seem to be traces of basiradial and interradial sutures, and the position of the former, if real, would indicate that the basals are relatively much higher than they can possibly be in Holopus. The great peculiarity of Cyathidiwm spileccense, however, lies in the relative position of the radials in the pentagonal cup. Their articular surfaces correspond with the angles of the pentagon, and not with its sides, as is the case both in Holopus and in Steenstrup’s Cyathidium, while the middle of each side is raised into a slight ridge which separates the articular facets of two contiguous radials. The result of this is that the five openings of the radial canals are situated at the angles of the calyx. They occupy about the middle of the rim, the outer edge of which is slightly truncated, and shows traces of a fossa for an elastic hgament. The peculiar semilunar shape of these articular facets is considered by Zittel as one of the generic characters of Cyathidium. But it certainly does not appear in any of the Faxoe specimens which were lent to Sir Wyville Thomson by Prof. Lovén. We know too little about both of these species to make them types of different genera; and in default of further information it appears undesirable to unite them with Holopus. Both forms resemble and differ from it in various points, and are 1 Paléont. Frang., loc. cit., p. 187. * Astylide Crinoiden, loc. cit., pp. 50-54, Taf. iii. figs. 11-15. REPORT ON THE CRINOIDEA, 213 unquestionably very closely allied to it, but I am inclined to think that it would be premature to consider them all as congeneric. Two other fossil genera of Neocrinoids, Cotylecrinus and Eudesicrinus, both confined to the Lias, are nearly related to Holopus and Cyathidium, and should in my opinion be placed in the same family. This has been generally done with Cotylecrinus, which is perhaps better known by its older name of Cotylederma, Quenstedt. But Schliiter denied its relationship to Cyathidium,' which had been previously pointed out by Roemer? and Deslongschamps,’ on the ground that there are no perforated plates in Cotylecrinus. It is true that Quenstedt’s original specimens had no radials attached, and were therefore imperforate, as were most of those figured by Deslongschamps ; but the latter author also described and figured a fine specimen of Cotylecrinus docens, showing the large articular surfaces of the radials, and the openings of their central canals, just as in Cyathidium. This must surely have been overlooked by Schliiter, or he could scarcely have questioned the relationship of the two types. Both in Cotylecrinus and in de Loriol’s new genus Ludesicrinus, the radials rest wpon a more or less tubular structure which is slightly expanded below and has been variously described. In the former genus it has been called a stem by Quenstedt and by MM. Deslongschamps,* and a top stem-joint by Schliiter.’ Zittel® suggested that the upper part of it, which is marked by crests with intervening fossee for the reception of the radials, should be considered as composed of anchylosed basals, and that the lower part is a centro-dorsal ? De Loriol,’ however, considers the whole as a centro-dorsal piece, not having been able to find any trace of sutures separating the upper part from the lower. It is sometimes found in an isolated condition, while in other cases the radials still remain in connection with it, and form a perfectly symmetrical whole, no one of them preponderating in size over the others. They have only been seen in Cotylecrinus docens, in which they were first figured by Deslongschamps. As in Holopus and in Steenstrup’s Cyathidium, they correspond to the sides of the pentagon, and the dorsal fossa is greatly reduced. With regard to the so-called centro-dorsal of Cotylecrinus, I am decidedly of opinion that the upper portion on which the radials rest represents the basals. The absence of sutures noted by de Loriol is no proof to the contrary, as we know from the condition of the Paleozoic Allagecrinus and Agassizocrinus, and of the recent Rhizocrinus and Bathycrinus.* This is in fact tacitly admitted by de Loriol himself in the suggestion that the whole of the calyx tube in Holopus and Cyathidiwm consists of anchylosed basals.° If then the so-called cupule of Cotylecrinus, instead of being a centro-dorsal as its 1 Loe. ctt., p. 53. 2 Neues Jahrbuch fiir Mineralogie, 1857, p. 817. $ Mémoire sur la Couche 4 Leptena, Bull. Soc. Linn. de Normandie, t. iii. p. 181, pl. v. figs. 5, 6. 4 Op. cit., pp. 174, 179. 5 Loe cit., p. 53. 5 Palexontologie, p. 386. 7 Paléont. Frane., loc. cit., p. 190. ® See Ann. and Mag. Nat. Hist., 1883, ser. 5, vol. xi. p. 329. ® Paléont. Frang., loc. cit., p. 191. 214 THE VOYAGE OF H.M.S. CHALLENGER. name implies, really consists, either wholly or partially, of united basals, the composition of the calyx is the same as in Holopus and Cyathidiwm, in fact as in most Neocrinoids, few of which are dicyclic. In all cases of which we have full knowledge, the basals rest upon something representing a stem, the special organ which is so characteristic of the Crinoids. It may perhaps be only a central abactinal plate, which becomes ‘transformed into an expanded disk of attachment, as in the Pentacrinoid larva of Comatula. But I strongly suspect on general morphological grounds that the basal element im the cup of a Crinoid does not come into direct contact with the supporting surface ; and I have an equally strong suspicion that it is never entirely absent. The radials of all Crinoids, excepting the ordinary Comatulz, rest in fossee which are separated by interradial ridges that mark the median lines of the united basals (Pl. XX. figs. 2, 3). Such ridges occur in Cotylecrinus, the raised angles of the upper edge of the cupule being interradial im * and I-am therefore disposed to agree with Zittel in regarding them as belong- ing to basals, the lower limits of which are as yet unknown. There is another character, besides the symmetrical radials, in which Cotylecrinus resembles Cyathidium. This is the association of two or more individuals ina manner suggestive of a process of budding, both internal and external. Steenstrup noticed this peculiarity in Cyathidium, and de Loriol has described it in Cotylecrinus miliaris.” This last species is further remarkable from the fact that the outer surface both of the cup and of the second radials found associated with it, ‘‘ est couverte de petites pustules, tantédt un position ; peu écartées, tantdt, au contraire, trés serrées.” These at once recall the blunt tubercles of Holopus (Pls. I., II.). Cotylecrinus, Cyathidium, and Holopus are evidently very closely allied, though the two former differ from the latter in the symmetry of their radials. In the remarkable form, which after having been referred to Plicatocrinus and also to Eugeniacrinus, has been made the type of a new genus Hudesicrinus by de Loriol, there are, however, five asymmetrical radials. These rest “sur une base large, assez élevée, adhérente par un épitement aux corps soumarins. Cette base n’est point une piece centro-dorsale semblable a celle des Cotylecrinus, renfermant les parties molles de animal, c’est un simple support.” The radials of this type are much higher than those of Cotylecrinus, and enclose a less extensive space in the centre of the funnel which they form by their apposition. It narrows considerably below, however, and I question very much whether it contained more than quite a small portion, if any, of the digestive canal. But according to de Loriol® “ c’est donc dans la cavité formée par les piéces radiales que se trouvaient logées les parties molles de l’animal.” I suspect, however, that the greater part of the visceral mass lay above the surface of the cup, and was protected by the two outer radials and lower arm-joints, just as in Rhizocrinus and Bathycrinus (PI. VII. figs, 2)3:; Pl LX. figs ie eel x fio: 20), 1 Paléont. Frang., loc. cit., pl. 20, figs. 1, 2, 5, 6. 2 [bid., p. 204, pl. 19, figs. 15, 17. 5 Ibid., p. 98. REPORT ON THE CRINOIDEA. 215 With regard to the support beneath the radial pentagon of Hudesicrinus, I see no reason for doubting that the upper part consists of united basals. In fact, one of de Loriol’s figures! shows a distinct horizontal sutural line crossing the middle of the support, and separating the infra-radial portion with interradial crests on its upper surface from the more spreading, attached part below. In another specimen this suture seems to be indicated by an external circular ridge ; but the upper face of the support is marked by five petaloid depressions, one of them considerably larger than the rest, which surround acentral pit. De Loriol, and, I think, rightly so, regards these depressions as corresponding to the cavities of the chambered organ, the largest being that of the large radial in the trivium. Similar but more recular depressions appear round the middle of the upper surface of the large basal pentagon in Apiocrinus milleri, Quenstedt ; and they are also shown in de Loriol’s figure of Apiocrinus roissyanus, while it will be remembered that the chambered organ is invariably in close relation with the basals (Pl. VITb. figs. 1, 2; Pl; XXIV. figs. 6, 7; Pl. LVIII. figs. 1, 3—ch; Pl. LXI.). There can then, I think, be no doubt as to the presence of basals in Hudesicrinus, so that the so-called support does not in reality differ essentially from the centro-dorsal of Cotylecrinus. The radials, how- ever, are very different in the two cases.. Those of Cotylecrinus are equal and similar ; but in Eudesicrinus they are thus described by de Loriol,’ “Ces pieces sont fort inégales; lY'une est notablement plus longue et plus large que les autres, convexe et un peu arquée en dehors, mais d’une maniére uniforme ; les deux qui la touchent, bien plus courtes et plus étroites qu’elle-méme, ne sont guére plus larges, mais plus longues que les deux autres ; ces derniéres, qui sont les plus courtes et placées vis-A-vis de la plus large, s’arquent en dedans et se coudent un peu vers leur bord supérieur. Dans les échantillons frais la surface externe est couverte de granules épars, écartés, plus ou moins gros et plus ou moins serrés.” Here then we have a type which bears an unusually close resemblance to Holopus. The calyx is higher on one side than on the other owing to the inequality of the radials, the central one of the trivium being the largest, while the outer surface, not only of the radials, but also of the arm-joints, is coarsely granular or tubercular. Eudesicrinus, however, differs from Holopus in one or two minor points. The fossee on the radials which lodged the dorsal ligaments are larger; and there seems to have been a true muscular joint be- tween the second and the axillary radials, a character presented by no recent Crinoid, and also, so far as I know, by no other fossil species. In Hugeniacrinus mayalis from the same horizon the two joints are united by syzygy, just as I believe to be the case in Holopus, while the calyx is less.coarsely granular. These two species are quite small relatively to Holopus, the radials of Hudesicrinus not reaching a height of more than 11mm. Associated with them in the Leptena-bed (Middle to Upper Lias) of Calvados, in Normandy, are some wedge-shaped arm-joints with the muscle-plates on their broad outer sides produced into strong upward processes. These joints have very much the appear- 1 Paléont. Frang., loc. cit., pl. 29, fig. 7. * Ibid., pl. 44, fig. 2, 6. 3 [bid., p. 78. 4 Ibid., pl. 11, figs. 1-4. 216 THE VOYAGE OF H.M.S. CHALLENGER. ance of the more wedge-shaped brachials of a Holopus-arm (PI. IIL. figs. 10-12), but differ in having the pinnule-socket at the base of the lateral process instead of on its upper edge. Before the discovery of the support below the radials de Loriol considered Hudesi- erimus to be a species of Hugentacrinus ; and he still regards it as a member of the family Eugeniacrinidz, to which he has also thought of transferring Cotylecrinus, though he has never actually done so. This is partly due to his having been led to regard the calyx-tube of Holopus and Cyathidiwm as possibly composed of the five basal pieces only,’ though there are very serious objections to this view. We know also that the Eugeniacrinide, 1.e., Hugeniacrinus, Phyllocrinus, and Tetracrinus, have a jointed stem, which is not the case either in Hudesicrinus or in Cotylecrinus. Both these genera seem to me to find their proper place in the family Holopidee, which I should characterise as follows—Basals and radials closely united into a more or less tubular calyx of variable depth. It is sessile and attached by a somewhat spreading base, the foundation of which is probably formed by a dorsocentral plate, like that of Marsupites. Ten simple arms, composed of a small number of massive joints. A. Radials high but asymmetrical, exhibiting a difference of bivium and trivium. a. Radials fused together with basals into a tubular body-chamber lodging the viscera. A syzygy between the two outer radials, : ; : : - 1. Holopus. 8. Visceral mass was probably lodged above the radials, which are mostly found separated from the subjacent basals and the spreading base of attachment, A muscular joint between the two outer radials, : 5 : . 2. Eudesicrinus. B, Radials apparently all alike. Two or more calyces sometimes associated as if budding, a. Radials and basals fused into a tubular body-chamber, . Z * . 3. Cyathidium. B. Radials low, and readily separated from the basals and disk of attachment, . 4. Cotylecrinus. The remarkable Jurassic fossil, described by de Loriol as Gymnocrinus,® is still too imperfectly known to be placed in this family; but I cannot help suspecting that it is only a portion of the cup of a larger Crinoid. On the other hand, Micropocrinus gastaldv, described by Michelin® from the Miocene of Superga near Turin, seems to be closely allied to Holopus. Michelin’s diagnosis runs as follows: “Radix expansa, non ramosa, adhaerens, sublzevis ; corpus breve crassum, rotundatum, subpentagonale, exterius granulosum, interius profundum, irregulariter vacuum; margine revoluto in decem segmentis acutis subdiviso.” I am somewhat puzzled as to the identity of the ten marginal segments. I do not think that they can represent the individual muscle-plates, of which there would be ten in a decalcified calyx; nor does it seem likely that Micropocrinus is a ten-rayed type like Promachocrinus (ante, pp. 37, 38). The real nature of this Crinoid must therefore remain undecided for the present. On the other hand, the Paleozoic Edriocrinus, which has been described by Hall 1 Paléont. Frang., loc. cit., p. 191. 2 Tlid., p. 209. $ Description @’un nouveau genre de la Famille de Crinoides, Rev. et Mag. Zool., ser. 2, t. iii. p. 93. - tw | | REPORT ON THE CRINOIDEA. 217 from the Upper Silurian of North America, appears to be very closely allied to the recent Holopus and to Cotylecrinus. According to Meek and Worthen,’ it seems to differ from this last type “only in having an anal piece on the same range with the first radials, the relations between the two groups being exactly the same as between Hexacrinus and Platycrinus.” These two genera, however, are both Palzeocrinoids ; but Belemnocrinus and Rhizocrinus, a Paleocrinoid and a Neocrinoid respectively, are related im precisely the same way. The former, like Edriocrinus, has an anal plate in line with the radials ; while there is no such structure in Rhizocrinus nor in Cotylecrinus. The arms of Edriocrinus are more numerous than those of Holopus, as there are secondary axillaries beyond those in the radial series; but they were rolled in on one another very much after the manner of the Holopus-arms; and this was also the case in the Devonian Lecanocrinus roemeri, Schultze. The latter type has a stem; but this organ appears to have been altogether absent in Edriocrinus, which is thus described by Hall :2—*‘These Crinoids are sessile in the young state, adhering singly or in groups to other substances until fully developed, when they are separated from the foreign bodies, and gradually secreting ealeareous matter to cover the cicatrix or point of adhesion, become finally smooth rounded bases.” Elsewhere® again he described the radial plates as proceeding from this “short pedicle” as from the summit of a column. According to Wachsmuth and Springer‘ this pedicle really consists of five closely anchylosed, basal plates, with the sutures between them obliterated by a secondary calcareous deposit, which eventually removed all traces of the scar denoting the previous attached condition of the individual. The Mesozoic and recent Holopide do not seem ever to have passed into the “free” condition characteristic of Agassizocrinus and Hdriocrinus, so that there is no scar of attachment to be obliterated. But I strongly suspect that the subradial portion of the body, centro-dorsal, support, cupule, or whatever it be called, consists either wholly or (more probably) in great part of anchylosed basals, just as it does in the Paleozoic Edriocrinus.’ For I find it difficult to believe in the existence of a family of Crinoids which are normally devoid of any basal plates, as these are of fundamental importance both in the morphology of the Crinoids, and in that of Echinoderms generally. Family Hyocrinip, P. H. Carpenter, 1884. Genus Hyocrinus,’ Wyville Thomson, 1876. Definition.—Calyx high, and composed of basals and radials which are nearly equal in length. The former narrow gradually downwards, while the latter are broad and spade-like, each bearing a small undivided arm in the middle of its upper edge. Arm-joints united 1 Paleontology of Illinois, vol. iii. p. 371. 2 Natural History of New York, Paleeontology, vol. iii. p."120. 3 [hed., p. 143. 4 Revision, part i. p. 21. 5 Ann. and Mag. Nat. Hist., ser. 5, vol. xi., 1883, pp. 327-834 6 Named after Hog Island, one of the Crozets. (uooL. CHALL, EXP.—PART Xxx1L—1884.) Ji 28 218 THE VOYAGE OF H.M.S. CHALLENGER. _ by syzygy into groups of two or three, only the terminal jomts of which bear pinnules. Lowest pinnules the longest, and the following ones proportionately shorter, so that they all terminate on the same level as the arm-ends. Mouth protected by five large oral plates. Stem composed of short, cylindrical joints with simple or slightly striated faces. Mode of attachment unknown. A. GENERAL AccouNT OF THE TYPE. Hyocrinus bethellianus, Wyville Thomson, 1876 (Pl. Ve. figs. 4-10; Pl. VI). Hyoerinus bethellianus, Wyv. Thoms., Journ. Linn. Soc. Lond. (Zool.) (1876), 1878, vol. xiii. p. 51. Hyocrinus bethellianus, Wyv. Thoms., The Atlantic, 1877, vol. ii. pp. 96-99. Dimensions. Total length of calyx and arms ( ‘ie C. W. ©. a ; ; : - 60:00 mm. Total height of calyx, ; ‘ 5 F : T4255 3 Total diameter of calyx, 5 5 : 3 : ; : 6:00) =; Height of radial, F ; : : : d : : 4:00 ,, Width of radial, ‘ : : : é : : : 3:00), Height of oral plates, : : ; , ; : . PETG) Length of first pinnule, : : : ; 3 . eos OO lar Diameter of arm-joints, C . - : : : : L007, Greatest height of stem-joints, ; : ; : ; : ist) a5 Diameter of stem-joints, : ; ; ; : ; . 1:25 ,, The stem is rigid, and consists of short, cylindrical joints, usually a trifle higher than wide, and closely united by thin disks of ligamentous fibres (Pl. Ve. fig. 5, Js). The terminal faces of the joints (Pl. Ve. fig. 4) are slightly hollowed, and either plain or marked with indistinet radiating striez. The opening of the central canal is more or less definitely stellate, and in the substance of each joint itself there is a considerable space (Pl. Ve. fig. 5, rs) around the central axis (ca). The longest portion of the stem obtained was about 170 mm. in length, but its mode of attachment is not known. Towards the upper end the joints become much shorter, and in the uppermost 5 mm. they are mere disks with a slightly increased width (Pl. VI. fig. 3). The cup, which enlarges gradually upwards, consists of two tiers of very thin plates, the basals and radials, the latter being rather the higher of the two. The basiradial and the five interradial sutures are fairly distinct, but neither in the specimen represented in Pl. VI. nor in a fragment from the same locality, can I make out more than three interbasal sutures. Were it not that this seems to be the case in both specimens, I should be inclined to regard it as unim- portant; but under the circumstances I think we must consider that the lower part of the cup consists of two larger pieces and one smaller one, as in.certain Palocrinoids. The small single basal is the one immediately to the right of the anus, ¢.e., in the interradius beyond the anus to a watch-hand, when the disk is placed upwards. The remainder of REPORT ON THE CRINOIDEA. 219 the cup and the arms cannot be better described than in the words of Sir Wyville Thomson.* “The second tier consists of five radials, which are thin, broad, and spade- shaped, with a slight blunt ridge running up the centre and ending in a narrow articulating surface for an almost cylindrical first brachial. “The arms are five in number, they consist of long cylindrical joints deeply grooved within, and intersected by syzygial junctions. The first three joints in each arm consist each of two parts separated by a syzygy; the third joint bears at its distal end an arti- culating facet from which a pinnule springs. The fourth arm-joint is intersected by two syzygies, and thus consists of three parts; and so do-all the succeeding joints; and each joint gives off a pinnule from its distal end, the pinnules arising from either side of the arm alternately. The proximal pinnules are very long, running on nearly to the end of the arm; and the succeeding pinnules are gradually shorter, all of them, however, running out nearly to the end of the arm, so that distally the ends of the five arms and the ends of all the pinnules meet nearly on a level.” In all cases the first pinnule is on the left side of the arm. I can say nothing as to the total number of pinnules, the longest arm remaining having six of these appendages on each side. Owing to the large size of the pinnules in comparison with the arms, the epizygal joints to which they are articulated have the appearance rather of axillaries than of ordinary brachials. This is also the case in Rhizocrinus, but to a less extent (Pl. IX. figs. 4, 5). But as these appendages are simple and contain the genital glands like the pinnules of other Crinoids, they are undoubtedly of that nature, and must not be regarded as branches of the arms. The mouth is protected by a very perfect, five-sided pyramid of triangular oral plates, the outer surfaces of which are deeply hollowed along the median line (Pl. VI. figs. 1-4), while the imner surface slopes away rapidly on either side from a strong central keel (Pl. VI. fig. 5). Sir Wyville Thomson described it as marked with deep impressions for the insertion of muscles ; but I believe him to have been mistaken in this point. There is no trace whatever of any such muscles being attached to the inner surface of the oral plates in the mutilated specimen represented in fig. 5; while the orals of Rhizocrinus and of the Pentacrinoid larva of Comatula are certainly not so provided with muscles, and there are no @ priori reasons whatever for invoking their presence in Hyocrinus. About half the diameter of the disk is occupied by the oral pyramid which covers up the central mouth. Between its base and the edge of the cup there is a pavement of closely set, thin plates belonging to the anambulacral system, which have no regularity either of form or of arrangement. Some of these extend upwards on to the anal tube, which is situated near the edge of the disk in one of the interradial spaces. As in Rhizocrinus the oral plates are pierced by the ciliated water-pores which lead downwards into the body-cavity (Pl. Ve. fig. 6, wp). But the pores are more numerous than in Rhizocrinus, which has only one in each oral plate. In both the specimens of Hyocrinus which I have 1Journ. Linn. Soc Lond. (Zool.), vol. xiii. p. 52. 220 THE VOYAGE OF H.M.S. CHALLENGER. examined there are two pores in the oral plate of the anal interradius, and there are no others in any of the anambulacral plates which lie between it and the edges of the radials. The remaining oral plates, however, are not invariably pierced by the water-pores, as pointed out in Chapter VI. (ante, p. 95). The five ambulacra which radiate outwards from the mouth are protected as soon as they have passed through the angles of the oral pyramid by a very complete armour of caleareous plates (Pl. VI. fig. 3). This seems, as in most recent Crinoids, to be less completely differentiated on the arms than on the pinnules. In the wider, basal and middle portions of the pinnules which contain the fusiform genital glands, every pinnule-joint supports two or three quadrate side plates upon each side (Pl. Ve. figs. 9, 10, sp). Upon each of the side plates rests one of the covering plates (ep), which overlap one another alternately from opposite sides. There are no large side plates, however, in the narrow, proximal portion of the pinnule before the genital cord swells out into the fusiform genital gland; but the covering plates are separated from the pinnule-joints by a number of small irregular plates which belong to the anambulacral system (Pl. Ve. fig. 10). ‘Towards the distal end of the pinnule, on the other hand, the covering plates rest directly upon the edges of the pinnule-joints (Pl. Ve. figs. 8, 9; Pl. VI. fig. 6), as is the case throughout the entire length of the ambulacrum in Bathycrinus and Rhizocrinus (Pl. VI. fig. 7; Pl. VIIL figs. 4,5; Pl IX. figs. 2, 4). They are of a slightly oval shape, and may be as much as 0°6 mm. in diameter. The genital glands are long and fusiform, and give a swollen appearance to the lower portions of the pinnules (Pl. VI. fig. 1). This lasts for about six or seven of the elongated joints, after which the pinnules taper away slowly to their extremities, while the glands themselves are continued onwards for some little distance as delicate cords which often have a somewhat undulating course, and gradually diminish in size until they are no longer traceable (PI. Ve. fig. 8, t). The axial cord of the skeleton (a) is also thrown more or less into curves. The specimen obtained was a male, and the testes have lost all trace of histological structure, as seems to be not unfrequently the case with these glands in other species of Crinoids. They fill up the cavity of the pinnule almost entirely (Pl. Ve. fig. 7, t). A reduced cceliac canal (cc) with its ciliated cups (cic) being visible below the gland in transverse section ; while a small subtentacular canal (stc) intervenes between it and the water-vessel. The ambulacral nerve and blood-vessel, however, could not be detected, though there can of course be no possible doubt as to their presence. In one of the fragments’ which was obtained, the interior of the oral pyramid is exposed (Pl. VI. fig. 5). There is a ring of tentacles around the mouth, and, so far as can be judged from the condition of the specimen, there seem to be four of these on either side of the strong median keel of each oral plate, so that there would be forty in all. 1 Mr. Black did not see the original of this figure, but simply copied the woodcut, drawn in the first instance by Mr. Wild, which appeared in the Journ. Linn. Soc. Lond. Zool.) vol. xiii. p. 54, and subsequently in The Atlantic vol. ii. p. 96. REPORT ON THE CRINOIDEA. 221 The mouth leads into a funnel-shaped gullet, the internal epithelial lining of which is raised into strong glandular ridges, as is the case all along the first part of the digestive tract. There is no stomachie dilatation, but the tubular lower portion of the cesophageal funnel is continued into a narrow intestine which forms one simple loop, and turns upwards again to end in the anal opening, as shown in the right hand portion of Pl. VI. fig. 5. The body-cavity is occupied by the usual loose network of connective tissue, with dark brown granules dispersed through it in abundance. It is not strengthened, however, by any of the calcareous rods and plates which are so often found in a similar position in other Crinoids. Careful search also reveals the presence of visceral blood-vessels interpenetrating its meshes ; but I have not been able to discover satisfactory evidence of any water-tubes depending from the oral ring into the body- cavity, although these organs must certainly be present, and are probably numerous, like the water-pores on the disk. The colour of the spirit-specimen is a light yellowish-white. Localities.—Station 106. August 25, 1873; lat. 1° 47’ N., long. 24° 26 ’W.; 1850 fathoms; Globigerina ooze; bottom temperature, 36°°6 F. (1°°8 C.). Stem-fragments only (jide C: W. T.): Station 147. December 30, 1873; west of the Crozets; lat. 46° 16’S., long. 48° 27’ E.; 1600 fathoms; Diatom ooze; bottom temperature, 34°°2 F. (0°°8 C.). “One or two complete specimens and several fragmentary portions” (fide C. W. T.). The stem-fragments from Station 106 seem to have been mislaid; as neither Mr. Murray nor I have been able to find them in the collection of Crinoids which was in Sir Wyville’s hands at the time of his death, and was subsequently sent on tome. But the characters of the stem are unmistakable, being utterly different from those of either Bathycrinus or Rhizocrinus ; and unless the fragments in question belonged to a new generic type altogether, which seems improbable, I see no reason for doubting Sir Wyville’s identification of them with the Hyocrinus which he dredged four months later at Station 147. The point is one of some interest as regards distribution, for Station 106 is in the Mid Atlantic, just north of the Equator, while No. 147 is in the Southern Ocean, 30 miles to the westward of the Crozet group. The mention of ‘‘ one or two complete specimens ” said to have been obtained at this Station is unfortunately somewhat ambiguous. The original of figs. 1-4 on Pl. VI. seems to have been obtained in a fairly complete condition, lacking, however, the attached portion of the stem; but I am sorry to say that the stem and the head have since parted company. Another stem-fragment was sent me with portions of the thin basals still in connection with its upper end, and also two fragments of the disk, one with four of the oral plates (Pl. VL. fig. 5), and the other with the remaining plate (PI. Ve. fig. 6). These were mounted in balsam by the late Dr. von Willemoes Suhm, and doubtless belong to the stem-fragment just mentioned, but the greater part of the cup is wanting. Sir Wyville concluded his first account of Hyocrinus hy a reference to a specimen 222 THE VOYAGE OF H.M.S. CHALLENGER. which he provisionally named Hyocrinus bethellianus? with the following remarks :— “The last is a beautiful little thing which we dredged from a depth of 2325 fathoms at Station 223, in lat. 5° 31’ N., long. 145° 13’ E., in the east Pacific, with a bottom of Globigerina ooze, and a bottom-temperature of 1°°2C. It certainly is in many respects very unlike the adult Hyocrinus bethellianus ; but it may possibly turn out to be the young of that species. There was only one specimen.”* No reference whatever was made to this type in the description of Hyocrinus which was subsequently published in The Atlantic, and is substantially the same as that which appeared in the Journal of the Linnean Society. One would be inclined to conclude from this that the specimen in question was not a young Hyocrinus after all; for even though it was obtained in the Pacifie, reference would probably have been made to it in Sir Wyville’s later account of this very interesting genus. But as the specimen has totally disappeared, and has eluded all Mr. Murray’s anxious search, I am naturally unable to say anything about it. B. On tue Systematic Position or Hyocrinus. Hyocrinus was established by Sir Wyville Thomson in the year 1876,’ with the remark that “it presents certain general resemblances and even certain correspondences in structure which seem to associate it also with Rhizocrinus. There seems little doubt that Rhizocrinus finds its nearest known ally in the Chalk and Tertiary Bourgueticrinus, and that it must be referred to the neighbourhood of the Apiocrinide. Were it not that Bathycrinus and Hyocrinus are so evidently related to Rhizocrinus, the characters of the Apiocrinidee are so obscure in the two first-named genera that one would certainly have scarcely been inclined to associate them with that group.” Bathycrinus, though an aberrant form, is far more closely related to Rhizocrinus than Hyocrinus is. It has the same form of stem-joint and the same absence of pinnules from the arm-bases ; while the arm-joints themselves are united in pairs in a very nearly similar manner in both genera. But except in this last point, there is no resemblance between Rhizocrinus and Hyocrinus. The only known species of the latter genus was said by Sir Wyville Thomson to have “much the appearance, and in some prominent particulars it seems to have very much the structure, of the Palzozoic genus Platycrinus, or its subgenus Dichocrinus.”* In fact, Sir Wyville seems to have had considerable hesitation in referring Hyocrinus to the Apiocrinide ; and it was eventually associated by Zittel along with Plicatocrinus, in a family Plicatocrinide. But the definition which he gave of the family was far from bemg a satisfactory one, as it stated that basals were absent, which is by no means the case in Hyocrinus, and also that there are long, forked arms. Since then, however, he has found that there is an axillary second radial (first brachial, Zittel) in Plicatocrinus, which thus 1 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p. 55. 2 Tbid., p. 48. 3 Ibid., p. 51. ’) =. "eee REPORT ON THE CRINOIDEA. 223 has twelve (ten) arms, instead of five, as in Hyocrinus. These arms are composed of short, stiff joints in which no syzygial unions occur; while they bear short pinnules, ul of which, except the first four, consist merely of one elongated joint. Zittel further says,’ “ Aus dem Vorhergesagten geht hervor, dass Hyocrinus in Bezug auf den Bau der Arme einen differenzirteren Typus darstellt als Plicatocrinus. Immerhin aber stimmen beide Gattungen hinsichtlich ihres Kelchbaues besser mit einander iiberein, als mit irgend einer anderen bis jetzt bekannten Crinoideen-Genus und durften darum wohl derselben Familie zugetheilt bleiben.” It appears to me, however, that this supposed resemblance between Hyocrinus and Plicatocrinus is really very superficial ; and that it consists essentially in the condition of the thin and somewhat flattened calyx-plates. This is also the case with the radials of Bathycrinus, while the ealyces of young Penta- crinide have a very considerable similarity to that of Plicatocrinus. On the other hand, and apart from the question of basals, the arms of Plicatocrinus, as discovered and described by Zittel himself, are utterly and entirely different from those of Hyocrinus ; and although de Loriol says, ‘‘ Les analogies tendrent 4 montrer que les deux genres sont de la méme famille,”” he concludes as follows, “il faudra peut-étre établir une famille pour chacun de ces genres.” This I propose to do in the case of Hyocrinus, the definition of the family Hyocrinide being for the present the same as that given above for the genus. While resembling Apiocrinus and also many Paleoerinoids in the nature of the stem- joints, Hyocrinus differs in several respects from the other Neocrinoids. In the first place the apparent presence of only three basals and the small size of the articular facets as compared with the great breadth of the radials, give it a strong resemblance to some of the Palzeocrinoids, and more especially to the Platyerinide. Although Hyocrinus resembles Platycrinus in having a symmetrical, tripartite base, the position of the dorsal axis’ which divides the base symmetrically is not the same in the two genera. If a Platycrinus be “ orientirt” with the anal interradius posterior, the dorsal axis runs from the right anterior interradius to the left posterior radius; whereas that of Hyocrinus (ia the only specimen examined) runs from the left anterior radius to the right posterior interradius. But the general form of the calyx, as seen from the side (Pl. VI. fig. 3), is very like that of the Carboniferous Dichocrinus intermedius, figured by de Koninck.* Its composition, however, is different, as Dichocrinus only has two symmetrical basals. The persistence of the large oral plates is a noteworthy feature of Hyocrinus, but it finds a parallel in the Comatulid genus Thawmatocrinus (Pl. LVL fig. 5), and also to a certain extent in PRhizocrinus. 1 Ueber Plicatocrinus, Sitzwngsb. d. LI. Cl. k. baier. Akad. d. Wiss., 1882, Bd. i. p. 112. 2 Paléont. Frang., loe. cit., p. 63. 3 See Beyrich, Ueber die Basis der Crinoidea brachiata, Monatsber. d. hk. preuss. Akad. d. Wiss. Berlin, 1871, p- 42. * Recherches sur les Crinoides du terrain Carbonifére de la Belgique, Bruxelles, 1854, pl. iv. fig. 9. 224 THE VOYAGE OF H.M.S. CHALLENGER. It is in the character of the arms and pinnules, however, that Hyocrinus is most remarkable.’ The syzygial union of successive pairs of arm-joints is characteristic of Rhizocrinus; but in Hyocrinus the third and following joints are triple and not double only. A similar difference between the arms of Heterocrinus simplex and Heterocrinus constrictus has been already noticed." The arrangement of the pinnules of Hyocrinus was described by Sir Wyville Thomson s “hitherto entirely unknown in recent Crinoids, although we have something very close to it in some species of the Paleozoic genera Poteriocrinus and Cyathocrinus.”* 1 do not think, however, that this resemblance is such a very close one after all. For the lateral appendages of the arms of Hyocrinus, long as they may be, are true pinnules. Cyathocrinus, on the other hand, has no pinnules whatever, but long branching arms, each branch bifurcating several times. It is true that the terminations of all the branches are about on the same level, as is the case with the arms and pinnules of Hyocrinus. But in the one genus a bifurcation gives rise to two equal arms which divide again, and in the other there is no bifurcation at all, but the arm-joints bear a series of pinnules which remain perfectly simple throughout their whole length, great though this may be. It has been already pointed out that the nearest approach to the pinnule arrangement of Hyocrinus is to be found in Barycrinus herculeus from the Carboniferous series of Indiana, United States (ante, p. 61). The so-called armlets of this type alternate with one another upon opposite sides of the main arm-trunk and bear no pinnules, so that they seem to correspond somewhat closely with the pinnules of Hyocrinus. ; The closest approximation among the Necuenaids to the arrangement of the pinnules which occurs in Hyocrinus, though still differing from it in important points, seems to me to be found in the Liassic genus Hxtracrinus. In this curious type each arm consists of a principal trunk bearing pinnules as usual, and giving off at intervals from its inner side a series of smaller armlets which also bear pinnules. The lowest of these are as long as the remaining portion of the arm-trunk from which they spring; and the following ones are of successively diminishing lengths, so that the ends of the original arm-trunk and of its numerous armlets are all on about the same level. In this respect the armlets of Hxtracrinus are comparable to the pinnules of Hyocrinus; but they bear pinnules themselves, and only come off from one side of the main arm-trunk, instead of alternating from opposite sides. There is, therefore, no exact parallel to the condition of the arms of Hyocrinus to be found in any Neocrinoid; and remembering this, as well as the peculiarities of the calyx, we cannot say that Hyocrinus is specially related to any of the other Neocrinoidea, while it presents important characters which connect it with the Paleeocrinoids. 1 Ante, p. 53. 2 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p. 52. REPORT ON THE CRINOIDEA. 220 Family Boureveticrinip%, de Loriol, 1882. Genus Bathycrinus, Wyville Thomson, 1872; emend. P. H. Carpenter, 1884. Tlycrinus, Danielssen and Koren, Nyt Mag. f. Naturvidensk., 1877, Bd. xxiii. p. 4. Definition —Stem consisting of dicebox-shaped joints and attached by a branching root, the joints above which bear no cirri. The upper part of the stem, immediately beneath the cup, is formed of a large number of thin, discoidal joints. Calyx expanding upwards from the basals, which are closely united into a thickened, discoidal piece without any visible sutures, and but slightly wider than the upper stem-joints. First radials trapezoidal, and united to form a rapidly expanding cup. Second and third (axillary) radials united by trifascial articulation; the muscle-plates of the axillaries produced upwards into strong, wing-like processes. Arm-joints (with the exception of the third, sixth, and ninth) united in pairs by trifascial articulations, only the distal jomt of each pair bearing a pinnule, and there are no pinnules on the first few pairs. Interradial areas of the disk naked, paved with loose anambulacral plates, or supported by a single oral plate. Am- bulacra have covering plates, but no side plates. Remarks.—This genus was established by Sir Wyville Thomson in 1872 for a small immature individual which was dredged at the mouth of the Bay of Biscay by the “ Porcupine ” in 1869 from a depth of 2435 fathoms.’ But since the discovery by the Challenger of adult examples of two much larger species in the Atlantic and Southern Oceans, the original description of the genus requires modification. One of the Challenger species (Bathycrinus aldrichianus) was described by Sir Wyville in the Journal of the Linnean Society for 1876 ;-but in the meantime a fourth species was discovered in the North Atlantic by the Norwegian North Sea Expedition, and it was made the type of a new genus Ilycrinus by Danielssen and Koren.’ For it appeared to them to differ chiefly in size and in the presence of pinnules from Bathycrinus, as described by Six Wyville from the immature “ Porcupine” specimen; and his amended account of the genus, founded on the examples dredged by the Challenger, had not reached them in time for reference. The nearest ally of Bathycrinus is undoubtedly Rhizocrinus. In fact, without an acquaintance with this genus, one would hesitate to place Bathycrinus in the neighbour- hood of the Apiocrinide at all. There is but a very slight upward expansion of the stem below the head and even in the ring of basals which rests upon it; while the characters of the radials are very different from those of Rhizocrinus and Bourgueticrinus. The general character of the dicebox-shaped stem-joints and of the branching root is essentially the same as in Rhizocrinus. But the modes in which these joints are 1 Proc. Roy. Soc. Edin., 1872, vol. vii. p. 772; see also The Depths of the Sea, p. 450. 2 Nyt Mag. f. Naturvidensk., Bd. xxiii. p. 10. (ZOOL, CHALL, EXP.—PART Xxx1I.—1884,) li 29 226 THE VOYAGE OF H.M.S. CHALLENGER. developed from the thin disks that successively appear immediately beneath the calyx are different in the two genera (ante, pp. 26, 27). There is always a large number of these thin joints at the top of the stem of Bathycrinus (Pl. VI. figs. 1-3, 11; Pl. VIIa. fig. 1), whereas in Rhizocrinus (Pl. IX. figs. 1-3; Pl. LUI. figs. 7, 8) there are very few, often not more than one or two, and these by no means so thin as in Bathycrinus. An entire stem, or the upper and middle part of one, could therefore be referred without difficulty to its proper genus. But the lower and middle joints are so much alike in the two genera that the proper identification of a fragment or of isolated joints, either recent or fossil, would become a matter of uncertainty, if not of impossibility. The genus Bathycrinus was never formally defined by Sir Wyville Thomson ; but in his first account of it’ he said that, like Rhizocrinus, it “must also be referred to the Apiocrinide, since the lower portion of the head consists of a gradually expanding funnel- shaped piece, which seems to be composed of coalesced upper stem-joints;” and he nowhere mentioned the presence of any calycular plates below the radials. Subsequently, however, he stated,’ after examining Bathycrinus aldrichianus, that the stem of this 2 genus “ barely enlarges at its junction with the cup ;” and he described the lower portion of the latter as consisting of a series of basals which are soldered together into a small ring, scarcely to be distinguished from the upper stem-jomt (Pl. VII. figs. 1, 2, 11; Pl, Vila. figs. 12-14; Pl. VIIb. figs. 1, 2), The existence of basals in Ilycrinus (Bathycrinus) car- pentert was also recognised by Danielssen and Koren,’ who were fortunately able to see the interbasal sutures in young individuals, though these entirely disappear in the adult. Although invisible on the upper and lower surfaces of the basal ring of Bathycrinus aldrichianus, as well as externally (Pl. VIla. figs. 12-14), the sutures are clearly seen in sections through its middle portion (PI. VIIb. fig. 2). It expands very Fie. 11.—Diagram of a horizontal section through the lowest portion of the basal ring of Bathycrinus aldrichianus ; x 70. bl, ligaments uniting the basals to the top stem-joint ; ch’, the outer vessels in the vascular axis, which are continued downwards from the chambers of the chambered organ ; af, interradial portions of the fib- rillar sheath round the vascular axis which are separated by 7s, the radial spaces in the upper part of the stem; v, central vessel of the vascular axis. slightly from below upwards, and its somewhat hollowed under surface is marked by ten fosse radiating outwards from the centre and separated by intervening ridges (Pl. VIIa. fig. 14). They correspond to similar fossee on the upper face of the thin top stem-joint (Pl. VIIa. fig. 3), and lodge five strong but short interradial ligamentous bundles, each having somewhat the form of a horseshoe or V with thick limbs (woodcut, fig. 11, b/). These, as already described, unite the basals to the thin, upper stem-joints, and are gradually replaced as the joints become thicker by the two larger bundles which form cushion-like pads between every two of them (ante, p, 27; Pl. VIIa. figs. 4-6). 1 The Depths of the Sea, p. 450. 2 Journ. Linn. Soc. Lond. (Zool.), vol. xiii. (1876) 1878, pp. 48, 50. 3 Nyt Mag. f. Naturvidensk., Bd. xxiii. pp. 4, 5. REPORT ON THE CRINOIDEA. 227 Although in sections through the lower part of the basal ring the limits of its component joints may be traced by the grouping of the five ligaments referred to above, yet the interbasal sutures do not become clearly visible till the level of the lowest part of the chambered organ is reached. Here they appear as actual gaps in the otherwise contiuous network of nucleated connective tissue which forms the organic basis of the skeleton, so that in a stained preparation they are shown as five radiating white lines on a coloured ground (Pl. VIIb. fig. 2). They do not, however, reach the outer edge of the section where the connective tissue network forms a complete ring, and this accounts for the absence of any sutural lines upon the exterior of the composite basal piece (Pl. VIa. fig. 13). The sutural union between this piece and the stem-joints below it appears to be closer than that between the basals and radials, so that the head has a considerable tendency to break away from the stem at the basiradial suture. This was unfortunately the case with one of the two individuals of Bathycrinus gracilis which were met with by the “ Porcupine’s” dredge in 1869, and the head was consequently not brought to the surface. On the other hand, only the head of Bathycrinus campbellianus is now known (Pl. VIII. figs. 1,2. Woodeut, fig. 15 on p. 239), the stem with the basals having separated from it ; while Danielssen and Koren figure an isolated head of Bathycrinus carpenteri which has lost its basals But the most remarkable case of this kind was met with at Station 146, in the Southern Ocean, where the dredge must have passed over a small forest of Bathycrinus aldrichianus. About a dozen tolerably perfect individuals were obtained, together with a consider- able number of stems retaining the basal ring at their upper ends. This fact is one of no little importance from the light which it throws on the supposed composition of the calyx in the fossil genus EHugeniacrinus and its allies Phyllocrinus and Tetracrinus. These genera are very common in the Jurassic and Lower Cretaceous rocks, especially of the Continent ; but by far the greater number of calyces which are met with consist of the radials alone, just like that of Bathycrinus campbellianus (Pl. VIII. figs. 1, 2), and the family has accordingly been described as distinguished by the absence of basals. De Loriol’ says, for example, “ Le calice est formé de pieces radiales seulement sans pieces basales.” Occasionally, however, a calyx is met with still retaining a portion of the stem attached to it. But no sign of sutures is visible in what appears to be its uppermost joint immediately beneath the radials. This joint, with a portion of the stem attached to it below, is also sometimes met with separate from the radials, as in the case of Bathy- crinus aldrichianus and Bathycrinus gracilis. But the absence of sutures, as shown by the condition of an adult Bathycrinus, is no proof that the piece in question does not consist of a ring of closely united basals, a point as to which I have no doubt whatever.’ The fibres which effect the synostosis of the basals with the radials above them are 1 Nyt Mag. f. Naturvidensk., Bd. xxiii. Tab. i. fig. 6. 2 Paléont. Frang., loc. cit., p. 74. 3 Ann. and Mag. Nat. Hist., 1883, ser. 5, vol. xi, pp. 327-334. 228 THE VOYAGE OF H.M.S. CHALLENGER. rather more uniformly distributed over the apposed surfaces of the joints than those uniting the basals to the top of the stem. The upper surface of the basal ring presents five smooth and single sutural fossee for the attachment of the radials. They slope downwards and outwards from the edge of the central funnel, and each is marked near its outer edge by a single crescentic opening, or by two smaller ones in close proximity (PL VIla. figs. 12, 13). At first sight this more or less double opening would naturally be taken for the termination of the converging right and left forks of two adjacent interradial canals within the basal ring. This apparently obvious explanation is, however, very far from being the true one. The under faces of the radials which rest in these fossee on the upper surface of the basal ring are marked in the same way by more or less double openings ; but these are not the openings of the central canals, as the apparently similar openings are on the under faces of the radials of Pentacrinus and Metacrinus (Pl. XII. figs. 11, 22; Pl. XX. fig. 9; Pl. L. fig. 5). They are usually quite small and inconspicuous, and not nearly so well defined as the openings of the central canals on the distal faces (PI. VIla. fig. 15), with which indeed they have no communication, for they are merely small pits into which portions of the basiradial ligament are inserted ; and the same is the case with the corresponding openings in the fossee on the upper surface of the basal ring (PI. VIa. figs. 12, 13). Although the fibres of the basiradial ligament are generally distributed over the whole synosteal surface, they are more especially concentrated in ten bundles which are lodged in ten corresponding pits on each of the apposed surfaces of the basal and radial circlets. Owing to the curvature of these surfaces, these more defined bundles are not shown in the section represented in Pl. VIIb. fig. 3, which passes rather Besant cae cite cma ernie above their level through the general plane of the hianus, at the level of the upper part of the x ° basiradial oy ai, primary inter: synostosis ; but in the next section they are clearly peared Leaman maine visible, cut somewhat obliquely as shown in the woodcut (fig. 12,2). Bothin the woodcut, and in Pl. VID. fig. 3, the axial cords (az) are seen to be situated interradially. They retain this position until they reach about half the height of the radial pentagon, where they fork for the first time; and the branches enter the radials by the openings in their lateral faces (Pl. VII. fig. 6a). The right branch of one fork and the left branch of its neighbour in the adjoining basal occupy converging canals in the intervening radial, which meet almost directly, so that there is only one opening on the distal face (Pl. VIla. fig. 15). The circular commissure of Bathycrinus is thus mainly formed by the actual branches of the primary interradial cords, and not by special interradial commissures uniting these branches as in the Comatule and Pentacrinide (Pl. XXIV. fig. 9, cco). This is also the REPORT ON THE CRINOIDEA. 229 case in Rhizoerinus, as pointed out by Ludwig ;' but Bathycrinus occupies an inter- mediate position between Rhizocrinus and the types just mentioned, for the two converging cords within each radial are united by an intraradial commissure just as in Pentacrinus and Rhizocrinus (Pl. VIIa. fig. 6; Pl. XXIV. fig. 9—ico). This does not appear in the section represented in Pl. VIIb. fig. 4, though it is plainly visible in the next one. The distribution of the axial cords proceeding from the chambered organ of Bathycrinus is thus of a very singular character (woodcuts, figs. 18, 14). Each of the five primary Fic. 13.—Diagrammatic vertical section through the Fig. 14.—Plan of the distribution of the calyx of Bathycrinus aldrichianus ; x 35. It is inter- axial cords in the calyx of Bathycrinus radial on the right side, passing between two of the aldrichianus. B, basals; R1 R2 first chambers of the chambered organ, and through the and second radials. synostosis of two radials (which is shaded darker) so as to show the primary interradial cord (ai); while on the left side it passes along the middle line of a ray, and shows the axial cord (A) in the distal part of the radial (R1). B, ring of anchylosed basals ; ca, fibrillar sheath round vascular axis of stem; ch, one of the chambers of the quinquelocular organ ; ch’, its down- ward extension into the stem ; c.co, interradial portion of circular commissure; 7, basiradial ligament; dd, dorsal ligament; Ui, interarticular ligament; m, muscle; v, central vessel of the stem; x, plexiform gland. interradial cords proceeds upwards close to the central axis of the basal ring (woodcut, fig. 13, at). They pass out of this ring just inside the edge of its central funnel, at the inner ends of the ridges which separate the fossee lodging the radials and marking the median lines of the basals. For the remainder of their course each of them is contained in the more or less complete canal which is formed by the apposition of two grooves, one on each of two contiguous lateral faces of the radials. These grooves, which run downwards from 1 Op. cit., Zeitschr. f. wiss. Zool., 1877, Bd. xxix. p. 72. ‘] ’ ’ ) I 230 THE VOYAGE OF H.M.S. CHALLENGER. the openings in the lateral faces of the radials, but close to their inner edges, are well shown in Pl. VII. fig. 6a. As in the Comatule, therefore, the circular commissure of Bathycrinus (Pl. VIIb. fig. 4, cco) is in the innermost part of the radial pentagon, 7.e., quite near its centre. There is but a thin layer of limestone between it and the central space, while almost the whole of the fibres forming the interradial ligaments are outside it. The length of these primary interradial cords and their reception in grooves on the apposed surfaces of contiguous radials is very anomalous; and although I detected the true nature of these grooves at first sight, it was nevertheless very long before I could get rid of the notion that the radial openings on the top of the basal ring (PI. VIa. figs. 12, 13) were those of the converging branches of the forked interradial canals, as in other Crinoids ; and it was not until after some time that I was able to reconcile the apparently conflicting evidence afforded by the study of series of transverse sections on the one hand and of the dissected calyx on the other. From the facts detailed above, it will be seen that Bathycrinus occupies a some- what anomalous position among Neocrinoids. In Comatula, Pentacrinus, Apiocrinus, and Hncrinus the primary interradial cords fork within the basals; and the adjacent branches of neighbouring forks enter the radials by more or less distinctly double openings on their inner or under faces; but in Bathycrinus not only do the cords not fork within the basal ring, but they rise through half the height of the radial pentagon before doing so (woodcuts, fig. 13, a7; fig. 14). The nearest approach to this condition is presented by Rhizocrinus, though the relative proportions of the plates are exactly the reverse of what we meet with in Bathycrinus. In fact, if we make allowance for this difference the condition of Bathycrinus, except for the presence of the intraradial com- missure, is almost exactly that which was described by Ludwig in Rhizocrinus; though, as pointed out already, the real condition of this genus is slightly more normal, 7.e., the primary cords fork within the basals, and their converging branches enter the inner ends of the radials as in other Crinoids. The first radials, which form by their apposition a rapidly expanding eup, have an elongated, trapezoidal outline and rounded outer surface. According to Sir Wyville Thomson,’ those of Bathycrinus aldrichianus are “ often free ; but in old examples they also are frequently anchylosed into a funnel-shaped piece.” In all specimens of this type which I have seen, however, the radials are united laterally, just as in other Crinoids ; though they separate more readily than usual when treated with hot alkalies. The ligaments uniting them are close and well defined in the lower part of the funnel (PI. VIIb. fig. 4, 7); but in the upper part, 7.e., just below the level of the articular surface, there is no interradial ligament (Pl. VIIb. fig. 5), which probably explains the description that has just been quoted from Sir Wyville Thomson. The distal articular faces of the radials 1 Journ. Linn. Soc. Lond. (Zool.), 1876, vol. xiii. p. 50. ler ee eT wie) REPORT ON THE CRINOIDEA. 231 are relatively large, but otherwise of the usual character, with paired fosse for the muscles and interarticular ligaments (PL VIa. fig. 15, rm’ and lv’), and the single one beneath the articular ridge for the reception of the dorsal ligament (/d’). The second radials (Pl. VII. figs. 5, 5a) are broad, flattened, and somewhat quadrate in form, with a more or less distinct medio-dorsal convexity (Pl. VIIb. fig. 6, R2) and a well-marked furrow in the middle line of the ventral surface (Pl. VII. fig. 5a). The proximal face resembles that of the first radials, which is high relatively to its width (Pl. Vila. fig. 15), while the articular surface at the distal end is low and much extended laterally. The axillaries are more or less pentagonal, with a forking median ridge on the flattened dorsal surface, The ventral surface is flattened like that of the second radial, with which the axillaries articulate without the sntervention of muscles. But the lateral margins of the median ventral furrow rise gradually from the distal to the proximal end of the joint, where they are produced into more or less expanded, wing-like processes which project forwards over the first brachials (Pl. VII. figs. 4, 4a; Pl. Via. fig. 17). The bases of these serve for the attachment of the muscles and ligaments which unite the axillaries and first brachials, while their upper portions support the interradial diverticula of the gut (Pl. VID. fig. 7, Rs). According to Sir Wyville Thomson, the two outer radials of Bathycrinus gracilis and Bathycrinus aldrichianus are united by syzygy ; while Danielssen and Koren make the same statement respecting Bathycrinus carpenteri.| This is not really the case, how- ever, and as a matter of fact there are no true syzygies in Bathycrinus aldrichianus to) at all; nor, as I believe, in any species of the genus. The distal face of the second radial isshown in Pl. VIIa. fig. 16. Apart from its external form, it has a general resem- plance to the corres ponding face of the second radial in Pentacrinus decorus, Penta- crinus naresianus (Pl. XXX. fig. 1; Pl. XXXIV. fig. 6) and the Comatulee, 2.e., there is a vertical articular ridge which separates the two fosse lodging large bundles of ligament (i’). But in Bathycrinus a third and smaller bundle of ligament is inserted into a deep pit (Id’) at the lower or dorsal end of the vertical articular ridge. The proximal face of the third radial is of the same character ; and in reality the union of these two joints, instead of being an immovable syzygy, is a modification of the bifascial articulation permitting lateral movement only, which is so common in the Comatule, and is also characteristic of four recent species of Pentacrinus. Externally this form of articulation looks very much like a syzygy, as the joints are brought into closer connec- tion than when they are united by a pair of muscular bundles; but a glance at their apposed faces is sufficient to show that the plainness of the syaygies in Pentacrinus or Rhizocrinus, and the striation so common in the Comatule, are altogether absent, being replaced by distinct ridges and fosse. In describing Bathycrinus gracilis, Sir Wyville Thomson’ pointed out that “the first brachial is united to the second by a 1 Nyt Mag. f. Naturvidensk., Ba. xxiii. p. 6. 2 Proc. Roy. Soc. Edin., 1872, vol. vii. p. 773. ip SK ees ie hai: , 232 THE VOYAGE OF H.M.S. CHALLENGER. syzygial joint, but after that the syzygies are not repeated, so that there is only one of these peculiar junctions in each arm. . , . And the alternate syzygies in the arms, which form so remarkable a character in Rhizocrinus, are absent.” He subsequently stated that in Bathyerinus aldrichianus “ the first and second, and the fourth and fifth brachials are united by syzygies; and after that the syzygies oceur sparingly and at irregular intervals along the arms.”* Jn like manner Danielssen and Koren’ described the first two brachials of Bathycrinus carpenteri as united by syzygy; a true articulation between the second and third, and also between the third and fourth brachials ; while the fourth and the fifth are united by syzygy, the sixth articulated both to the fifth and to the seventh, and the ninth both to the eighth and tenth. After this point muscular articulations and syzygies alternate all along the arms. Owing to the kindness of Dr. Danielssen I have been able to satisfy myself that these “syzygial unions” in the arms of Bathycrinus carpenteri are really trifascial articulations like that between the two outer radials of Bathycrinus aldrichianus. If, however, this term be substituted for syzygy in the description by Danielssen and Koren, their statements respecting the grouping of the brachials would be perfectly correct, z.e., in the nine lowest brachials there are alternations of a pair of joints united by trifascial articulation and a single joint with muscular articulations at both ends. Beyond the ninth brachial the two forms of articulation alternate with great regularity. Apart from the question of nomenclature, therefore, the Norwegian naturalists were the first who correctly described the grouping of the joints in the arms of Bathycrinus; for I find that their description of Bathycrinus carpenter: applies both to the little Bathy- erinus gracilis dredged by the “ Porcupine” and to the two Challenger species, Bathy- crinus aldrichianus (Pl. VIL figs. 1, 2) and Bathycrinus campbellianus (Pl. VILL. figs. 1, 3). The non-syzygial nature of the paired unions in the arms of the two last has been determined by actual investigation of the joint faces; while careful microscopic examination of the small individual of Bathycrinus gracilis has convinced me that it resembles the other three species in this respect. The proximal face of the fifth brachial of Bathyerinus aldrichianus is shown in Pl. Vila. fig. 19; and that of a later joint in fig. 20. In both cases the three fosse are visible around the opening of the central canal; while in Pl. VIIb. fig. 8, the three ligamentous bundles uniting the first and second brachials are seen in section (i, ld). The same three fosse (/i’, Id’) appear in Pl. VIla. fig. 22, which represents a trifascial articular face of Bathycrinus campbellianus; while an ordinary muscular joint-face at the proximal end of a brachial is seen in fig. 23, The presence of this trifascial articulation, and its peculiar grouping, may therefore be considered as distinctive of Bathyerinus. Hence the alternation which was referred to by Sir Wyville as so characteristic of Rhizocrinus is repeated in Bathycrinus, though with two points of difference. In the latter genus the syzygies of Rhizocrinus are replaced by ? Journ. Linn. Soc. Lond. (Zool.), 1876, vol. xiii. p. 50. 2 Nyt Mag. f. Naturvidensk., Bd. xxiii. pp. 6,7. REPORT ON THE. CRINOIDEA: 233 trifascial articulations ; while the third, sixth, and ninth brachials are usually free, ée., united by muscles to the joints before and behind them, as the joints of a Crinoid arm generally are. In Rhizocrinus, however, the two joints of each successive pair are united by syzygy, so that muscular articulations and syzygies alternate regularly all along the arm. But as regards the last point Bathycrinus approaches Rhizocrinus much more closely than was supposed by Sir Wyville Thomson. Instead of there being one syzygy (trifascial articulation) only, or two at the base and others scattered sparingly at irregular intervals, there is just as much regular alternation after the ninth brachial as there is throughout the whole arm of Rhizocrinus. In fact, in some irregular arms of Bathycrinus the third brachial is the only joint which has muscles attached at both ends, the alternation which would ordinarily commence with the tenth appearing on the fourth and following joints. Except in Bathycrinus aldrichianus the bases of the arms are but little wider than the succeeding portions. The flattening of the dorsal surface at the sides of the median ridge, which commences on the two outer radials, is continued on to the first two or three brachials and then disappears (PI. VIIb. figs. 7, 8). The same is the case with the sharp lateral edge which is so marked on the second and axillary radials. In Bathycrinus aldrichianus it is continued out on to the first eight arm-joints (Pl. VII. fig. 2), and marks the line of junction of the curved dorsal surface and the side faces, which slope upwards and inwards towards the medio-ventral line (Pl. VII. fig. 8). Anarm of this species, 30 mm. long, consists of fifty joints ; but the first seven or more bear no pinnules. In most cases the first pinnule is borne on the eleventh joint, when this, as is normally the case, has a muscular articulation at its distal end. The ninth brachial is usually a joint of this kind, and in Bathycrinus aldrichianus and Bathycrinus campbellianus some- times bears the first pinnule, while the eighth may do so. But the joint which bears a pinnule is invariably united to its successor by muscles, so that the pinnules only occur upon eyery alternate joint through the whole length of the arm, exactly as in Rhizocrinus. The only difference is that the joints which do not bear pinnules are united to those which do by syzygies in Rhizocrinus, and by trifascial articulation in Bathycrinus. The distal face of a pinnule-bearing joint of Bathycrinus aldrichianus is shown in Pl. VIIa. fig. 21; and a corresponding joint-face of Bathycrinus campbellianus in fig. 23. In the latter type the pinnule-socket is more at the side of the joint and less at the end than in Bathycrinus aldrichianus, The pinnules of Bathycrinus (Pl. VII. fig. 7; Pl. VIII. fig. 5) are moderately short and slender, and composed of relatively few joints. The. lateral edges of these joints, especially the outer ones, are produced upwards at the sides of the medio-ventral furrow so as to protect it very completely. This is most marked in Bathycrinus campbellianus (Pl. VIIL. fig. 5) and to a less degree in Bathycrinus aldrichianus (Pl. VII. figs. 2, 7). It is also figured by Danielssen and Koren’ in Bathycrinus carpentert. The first six or 1 Nyt Mag. f. Naturvidensk., Bd. xxiii., Tab. i. fig. 14, (ZOOL, CHALL, EXP,—PART XXx11.—1884.) Li 30 OT Fe LOR re eC ae a prea ae ee ibe s/n 234 THE VOYAGE OF H.M.S. CHALLENGER. eight pinnules which contain the short fusiform genital glands show this feature most distinctly. Somewhat the same character presents itself in the enlarged lower portions ’ of the long pinnules of Hyocrinus. But in this case the plate-like sides of the pinnule- joints diverge considerably, so that the median groove is widened instead of narrowed as in Bathycrinus. It is therefore partially roofed in by side plates (Pl. Ve. figs. 9, 10), of which there is no trace in Bathycrinus. But the plate-like sides of the joints bound a narrow ventral furrow, just as in the arms, and the covering plates rest directly upon their edges (Pl. VIL. figs. 7, 8; Pl VIII. figs. 3, 5), as is the case in Rhizocrinus and in the outer parts of the pinnules of Hyocrinus (Pl. Ve. fig. 9; Pl. IX. fig. 4; Pl. X. fig. 20). They are continued down the sides of the arm-grooves on to the disk, and in Bathycrinus aldrichianus, which has no orals, they stand up all round the edge of the peristome, as is represented, though badly, in Pl. VII. fig. 3. These covering plates are scarcely so substantial as the corresponding plates in Hyocrius, and are also narrower, though nearly as long. The two lower brachials and part of the third assist im the protection of the visceral mass, the upper surface of which is more or less strongly convex (Pl. VIL. fig. 3). There is a very large, funnel-shaped peristomial opening, at the bottom of which is the mouth, and the anus is on a low papilla in one of the five interradial areas. In Bathycrinus carpentert these are supported, according to Danielssen and Koren, by large retiform caleareous plates a little sunk in the perisome, which are obviously persistent orals, though they seem to be entirely absent in the three other species of the genus. In his preliminary description’ of Bathyerinus aldrichianus Sir Wyville Thomson said “ the disk is membranous, with scattered calcareous granules. The mouth is subcentral; there are no regular oral plates ; but there seems to be a determination of calcareous matter to five interradial points round the mouth, where it forms little irregular calcareous bosses.” This description was accompanied by a woodcut which was definitely stated to represent the Bathycrinus from Station 106 (in Mid-Atlantic), and not one of the numerous specimens obtained at Stations 146 and 147 inthe Southern Ocean. The whole set were at first regarded by Sir Wyville Thomson as belonging to one and the same species, to which he gave the name Bathycrinus aldrichianus ; but he subsequently limited this name to the individuals from the Southern Ocean. They are figured on Pl. VII., which was lettered and printed off before hisdeath. The disk of one of them isshown on Pl. VU. fig. 3, and obviously bears neither scattered calcareous granules nor interradial bosses round the mouth. This individual has not come into my hands; but the disk of another which I have examined is perfectly naked, except for the covering-plates at the sides of the ambulacra, and the peristome is like that shown in fig. 3. The specimen which was obtained at Station 106, and had been already figured in the Journal of the Linnean Society as Bathycrinus aldrichianus, was drawn by Mr. Black for P]. VIII. ; but on one 1 Journ. Linn. Soc. Lond. (Zool.), 1876, vol. xiii. pp. 50, 51 ; also in The Atlantic, 1877, vol. ii. pp. 92-95, fig. 23. NS Wat SSUES ee Vin eg aE i i le aaa Le Ne Ce ee ie 7 “tek ~ oes , ‘ REPORT ON THE CRINOIDEA. 235 of the copies of this plate which were sent to,me I found the MS. name Bathycrinus campbellianus in Sir Wyville’s handwriting. He had evidently therefore come to regard this individual as specifically distinct from those subsequently obtained in the Southern Ocean, to which he eventually limited the name Bathycrinus aldrichianus; and the disk of this individual (Bathyerinus campbellianus) corresponds in most respects with his description quoted above. The whole of each interradial area is covered with closely set, calcareous plates, not scattered granules ; but 1 cannot make out that they are more abundant in the immediate neighbourhood of the mouth than elsewhere. The covering plates of the ambulacra are smaller and less regular than in Bathyerinus aldrichianus, and their course can only be followed with difficulty. In the solitary young specimen of Bathycrinus gracilis (Pl. VIlla. fig. 1) there are neither orals nor anambulacral plates, so that in these respects it resembles the southern Bathycrinus aldrichianus rather than the northern Bathycrinus carpenters. In order that I might be able to compare the anatomy of Bathyerinus with that of Rhizocrinus, two of the least perfect examples were cut into thin sections with a Leyser’s microtome. Unfortunately, however, the circum-oral portions of the one used for the vertical sections were somewhat mutilated, and the remainder was found to be contracted, and, as it were, coagulated by the action of the spirit, so that not even its general anatomy could be made out, much less any histological detail. The arms, on the other hand, yielded more satisfactory results. In correspondence with the different size of the basals, the chambered organ (PI. VIIb. figs. 1,2, ch) is more flattened than that of Rhizocrinus. It is continued below into thé vas- cular axis of the stem, which is thrown into numerous folds as it passes through the closely packed discoidal joints at the top of the stem. Asin Rhizocrinus there is only one central vessel (PL. VIla. fig. 2; Pl. VIb. fig. 2—v), and not two or more as in some species of Pentacrinus and in the Comatulz. The plexiform gland rising from the chambered organ expands considerably within the central funnel of the calyx (PI. VIIb. figs. 1, 3-5, «), and soon becomes lobulate. It appears to be made up of numerous small cells, which can be traced downwards into the flattened epithelial lining of the vessels in its lower part, and in the chambers of the chambered organ. But it has nothing like the glandular appearance of the corresponding organ in Antedon carinata, the numerous lobules of which consist of distinct tubules lined by columnar cells, like those of the urinary tubules. On its way up through the disk the plexiform gland becomes narrower again, probably on account of its giving off extensions which form the intervisceral vessels, as in other Crinoids. It is interradial in position, as usual, and may be followed at the sides of the fore-gut both in transverse and in longitudinal section (Pl. VIIb. figs. 6-8, x) to a little way below the peristome, where its further course cannot be traced. I have little doubt, however, that its connections are essentially the same as in other Crinoids. But owing to 236 THE VOYAGE OF H.M.S. CHALLENGER. the imperfect condition of the top of the disk in the specimens which were cut, I have been quite unable to make out many details of structure. One point, however, is of interest, and that is that there are more than five water-tubes; for there seem to be three in each interradius, and not one only asin Rhizocrinus. As in this genus too, there are strongly marked interradial diverticula of the gut (Pl. VIIb. fig. 7), which are supported by the expanding processes attached to the inner faces of the third radials (ELA VEL, fie: 4a; Pl Vilage 17): . The arms of Bathycrinus present no essential anatomical differences from those of other Crinoids. The food-groove which is sunk within the ventral furrow of the skeleton (Pl. VIL. fig. 8; Pl. Villa. figs. 4, 5), instead of being some distance above it (Pl. LXI. figs. 4-6), is narrow relatively to the width of the arm, and protected by covering plates, as already described. The radial blood-vessel (Pl. VIIIa. figs. 4, 5, b) and ambulacral nerve (7) could be clearly distinguished in sections, the latter being exceedingly thin, or apparently sometimes even absent beneath the middle line of the ambulacrum. Except at the arm-bases the water-vessel (w) is relatively small, being much flattened from above downwards ; but the tentacles are large and bear numerous papille. Beneath the water-vessel, and projecting into the subtentacular canal, so as almost to divide it into two parts, is a more or less continuous band of closely nucleated connective tissue, which perhaps represents the structure marked « by Semper! in Actinometra parvicirra (Actinometra armata, Semper, MS.). At the bases of the arms the subtentacular canals are hardly traceable, their places bemg occupied by a complicated network of genital vessels, which are doubtless connected in the disk with the upper end of the plexiform gland, as in other Crinoids. But this plexus soon passes into a simple genital cord, as represented in Pl. VIIIa. figs. 4, 5, gc. It sometimes nearly fills up the small genital canal in which it lies, while there is a large and triangular cceliac canal beneath it (cc). The axial cords of the rays and arms of Bathycrinus, like that within the stem, are remarkable for the extensive subdivisions of the branches which proceed from them. Like those within the pinnules of Holopus and Hyocrinus (Pl. Ve. figs. 2, 3, 8, a), they take a somewhat wavy course within the radials, as is seen in Pl. VIIb. fig. 1, A; while the branches which come off from them in the second and third radials are shown in figs. 6,7, a’. Owing to the small height of these joints, the two dorsal branches which are usually so well defined in the Comatule (Pl. LXI. fig. 6) extend themselves laterally in the plane of the transverse articular ridge, while they are scarcely visible at all in the arms. On the other hand, the branches which extend upwards towards the ventral surface of the arm subdivide again and again, giving rise to a number of exceedingly fine fibrils, in the course of which bipolar, and occasionally multipolar, cells are clearly to be distinguished (Pl. VIIa. figs. 4,5, a’). This character is better shown in Bathyerinus than in any other Crinoid which I have yet examined. 1 Arbeiten aus dem zool.-zootom. Institut in Wiirzburg, 1874, Bd. i. p. 261. REPORT ON THE CRINOIDEA. Ii The nearest, and in fact the only ally of Bathycrinus is Rhizocrinus; but the differences between the two genera are much greater than their resemblances. The latter may be summarised as follows :—1. The hifascial union of the stem-joints. This is common to Bourgueticrinus and Mesocrinus, to the Pentacrinoid larva of Comatula, and the Paleozoic Platycrinus. 2. The presence of large processes on the second joints above the radials, which support the disk. 38. The absence of pinnules from the lower parts of the arms, and the union of the arm-joints in pairs, with a pinnule on the second joint of each pair only. The differences between the two types are shown in the following Scheme. Rhizocrinus. a. May have radicular cirri. b. Only one or two discoidal joints at the top of the stem, and those not very thin. c. Basals long; radials short, and very closely united. d. Primary interradial cords fork within the basals. e. Five arms, f. All the joints above the first radials are united in successive pairs by syzygy. g. The first pinnule may be either on the primitive sixth or eighth joint above the first Bathycrinus. a. No radicular cirri. b. Many thin discoidal joints at the top of the stem. c. Basals short; radials long, and comparatively free, d. Primary interradial cords fork within the sutures between the radials, e. Ten arms. fj. The fifth, eighth, and eleventh joints above the primary radials have a muscular articulation at each end; the remainder are united in pairs by trifascial articulations. g. The first pinnule not lower than the eleventh joint above the first radial. radial, z.e., on the epizygal of the third or fourth syzygial pair. It has been already pointed out that Bathycrinus ranges through a greater number of degrees of latitude than any other Stalked Crinoid, even Rhizocrinus; and it is only surpassed in this respect by the ubiquitous Antedon. Bathycrinus carpentert was found by the Norwegian North Sea Expedition as far north as 65° 55’ N. lat. ; while Bathycrinus aldrichianus was twice met with by the Challenger in the Southern Ocean beyond the parallel of 46° S. lat. In the intervening Atlantic Ocean have been found Bathycrinus gracilis (Bay of Biscay) and Bathycrinus campbellianus (just north of the equator) ; while other examples of the genus, the specific characters of which are as yet unknown, were dredged by the “Talisman” in the Atlantic (1883) at a depth of from 2000 to 2380 metres (1200 fathoms).! It is distinctly an abyssal type, ranging from 1050 to 2435 fathoms. The only Crinoids which have been found at greater depths than the latter are two species of Antedon. We have no certain knowledge of the occurrence of Bath ycrinus in the fossil state ; though it is by no means impossible that some of the stem-joints so common in the 1 Rapport préliminaire sur Vexpédition du “Talisman” dans VOcéan Atlantique, Comptes rendus, t, X¢vil. p. 1392. 238 THE VOYAGE OF H.M.S. CHALLENGER. Tertiary beds of the Continent may really belong to this genus. Meneghini has indeed suggested that two forms of joint found in the Italian Tertiaries are those of Bathycrinus;' but there is no evidence either for or against this idea. For the lower stem-joints of Bathycrinus are indistinguishable from the non-cirriferous jomts of Rhizocrinus, though the differences between the immature joints of the upper part of the stem may be readily recognised in the two genera. Key TO THE SPECIES OF BATHYCRINUS HEREIN DESCRIBED. I. The lower part of the radial funnel much constricted, é : . 1. Campbellianus. II. The radial funnel slopes uniformly downwards from the upper to the fo er edge. a. Calyx constricted at the basiradial suture. Basal ring scarcely wider above than below. Arm-joints smooth, 5 ‘ . 2. Aldrichianus. b. The slope of the radials is continued on to the basal ring, sah? is W He above than below. Arm-joints overlap, . : : : . 3. Gracilis. 1, Bathycrinus campbellianus, n. sp. (Pl. VIIa. figs. 22, 23; Pl. VIII.; woodcut, fig. 15). Bathycrinus aldrichianus, Wyv. Thoms. (pars), Journ. Linn. Soc. Lond. (Zool.), (1876), vol. xiii., 1878, pp. 47-51, fig. 1; The Atlantic, 1877, vol. ii. pp. 92-95, fig. 23. Dimensions. Total length of specimen, without stem, . é . : . 982°00 mm. Greatest height of radial funnel, . : 5 : ‘ : SON Greatest diameter, ; ‘ ji : ‘ : : 3008s; Least diameter, . : 4 : : : ; : 7A0) 55 Length of second radial, . : - : : ¢ 3 IGS5) Ms Length of third radial, : : 5 : : ‘ Talo ee Stem and basals unknown. Description of an Individual.—The radial funnel widens slightly from below upwards to just beneath its equator, where it expands considerably, owing to the dorsal surface of the radials suddenly becoming much more convex. The rim of the funnel is thus drawn out into five curved edges in which the second radials rest. They are trapezoidal in form, widen from below upwards, and have a strong medio-dorsal convexity which starts from the whole width of the lower edge and narrows rapidly till just beneath the dorsal edge, whence it is continued on the axillary. The lateral portions of the surfaces of both joints are flattened. The axillaries are shorter than the second radials, but wide and barely pentagonal in form, with a medio-dorsal ridge which forks at its proximal end and is continued on to the arm-bases, where it soon disappears. The flattened lateral portions 1 Processi. Verbali, Soc. Tose. di Sci. Nat., 7 Luglio 1878, p. xxxii. REPORT ON THE CRINOIDEA. 239 of the axillaries have sharp edges, and these are continued along the sides of the first three or four brachials, after which the joints become more cylindrical in form. The two lowest are squarish, and both, but especially the first, are wider than their successors, which are longer than wide, and overlap rather sharply both at the muscular and at the trifas- cial articulations, but more so at the former. The first pinnule is almost always on the ninth brachial, and the pinnules are attached some little way behind the distal edges of the joints which bear them, so that the socket is quite distinct from the articular face. The joints of the six or eight lower pinnules which are enlarged to hold the genital glands have a sharp dorsal edge and broad thin sides which are much produced upwards, but the later pinnules are more slender. The disk is paved with closely set plates. Colour, in spirit, white. Locality.—Station 106. August 25, 1873; lat. 1° 47’ N., long. 24° 26’ W.; 1850 fathoms ; Globigerina ooze ; bottom temperature, 36°°6 F. (1°°8 C.). One specimen, now without stem or basal ring. Remarks.—This species may be readily dis- tinguished from the other three by the shape of the funnel formed by the united first radials, and the overlap of the arm-joints. As pointed out already (ante, p. 234), it was not at first dif- ferentiated by Sir Wyville Thomson from the larger form obtained in the Southern Ocean, to which he ultimately limited the name Bathy- crinus aldrichianus. In fact it seems to be the type from which the description of Bathycrinus aldrichianus was mainly drawn up. Although an entire specimen was obtained, the stem Fic. 15.—Bathycrinu scampbellianus, nu. sp.; three times the natural size. appears to have separated from the head and to have been eventually lost; for otherwise we may take it for granted that the stem would have been drawn under Sir Wyville’s direction, together with the head belonging to it. In fact the upper part of the stem was drawn, together with the head, for the woodcut (fig. 15) which 240 THE VOYAGE OF H.M.S. CHALLENGER. appeared in the Journal of the Linnean Society, and also in The Atlantic. There can be no doubt that the head there represented is that of Bathycrinus campbel- lanus, owing to the strongly marked serration of the arm-joints, and the character of the pinnules. In fact the figure given in The Atlantic is definitely stated to represent the specimen from Station 106; while the fragment of a stem which it shows is entirely different from the upper part of the stem of Bathycrinus aldrichianus represented in Pl. VIL. fig. 11. The numerous thin joints immediately beneath the cup, which are so characteristic of the genus, are not properly represented in the woodcut, and the joints just below where these ought to be are considerably longer than one would expect to find so near the cup. It may be assumed that Mr. Wild’s drawing was photographie in its accuracy, so far as he could make out the structure of the small specimen ; but errors may have crept in during its reproduction on wood, and the cut was published during Sir Wyville’s absence from England, so that he had no opportunity of revising it. Under these circumstances, therefore, it appeared preferable to say nothing about the stem in the specific diagnosis given above, rather than to attempt to describe it from a probably incorrect woodcut. Two irregularities in the arrangement of the pinnules appear in this specimen. In one case the sixth brachial is not free as it normally is, but is-united to the seventh ; while the eighth is free instead of the ninth, and bears the first pinnule. In the other ease the ninth brachial is not free as usual, but is united to the tenth, which bears a pinnule, so that there are only two free joints, the third and the sixth. In his first account of the Challenger species of Bathycrinus, Sir Wyville Thomson? stated that “as the stalked Crinoids are perhaps the most remarkable of all the deep-sea groups, both on account of their extreme rarity and of the special interest of their paleontological relations,” he meant “to associate the names of those naval officers who have been chiefly concerned in carrying out the sounding, dredging, and trawling operations with the new species whose discovery is due to the patience and ability with which they have performed their task.” In accordance with this idea Sir Wyville established the new species Hyocrinus bethellianus and Bathycrinus aldrichianus ; and he left the MS. names Bathycrinus campbellianus and Pentacrinus naresianus upon the proofs of two of his plates. These names I have of course adopted. They refer to Lieutenant Lord George Campbell, and to Admiral Sir George Nares, who commanded the Challenger during the earlier part of the cruise. 1 Journ. Linn. Soc. Lond. (Zool.), 1876, vol. xiii. p. 47. REPORT ON THE CRINOIDEA. 241 Bathycrinus aldrichianus, Wyville Thomson, 1876 (Pl. VIL; Pl. Vila. figs. 1-21; fae Vili: Sun Wailer few ea): Bathycrinus aldrichianus, Wyv. Thoms. (pars), Journ. Linn. Soc. Lond. (Zool.) (1876) 1878, vol. xiii, pp. 47-51; The Atlantic, vol. ii. pp. 92-95, 1877. Dimensions. Greatest length of stem (fide C. W. T.), . : ‘ : » 200-250 mm. Longest stem-joints, : : , ; : : : 3°50 ,, Greatest width of lower joints, : 4 ‘ F : : 200m Total length of largest head, ‘ 6 ; : : : 30°00 _,, Height of basal ring, A , ‘ ‘ 3 s 2 0:80) =; Greatest height of radial funnel, . ; : : : : 2A Greatest diameter of radial funnel, . : ; : ‘ } 4°25 Least diameter of radial funnel, —. : : ; ; ; L540) Length of second radial, . ; j : : : : BHA) 5 Length of third radial, } : : : : : : TDs, Stem composed of about one hundred joints, of which the first twenty or twenty-five are wider than high, those immediately beneath the cup being mere circular disks, and slightly wider than the thicker ones on which they rest. The next joints below increase slowly in width and more rapidly in length. The ends are slightly expanded and the terminal faces oval-oblong in form. Their shorter diameter is occupied by a strong and continuous transverse ridge, the directions of the ridges on the two faces of any joint being nearly at right angles to one another. About the middle of the stem the diameter begins to increase more rapidly, and the ends of the joints appear less expanded while the terminal faces are circular; and near the base the diameter increases considerably, while the length remains the same or even slightly diminishes. The ends of the joints are considerably expanded and their faces oval, with their longer axes occupied by an articular ridge which is interrupted at the opening of the central canal. The stem ends below in a small branching root. The basals are closely united into a low, smooth ring, which is scarcely wider above than below, where it is of the same diameter as the thin uppermost stem-joints. On its upper surface rests the funnel-shaped radial pentagon which expands uniformly upwards to its distal edge, so that the calyx has the appearance of being much constricted at the basiradial suture. The surface of each radial is strongly convex in the middle but falls away at the sides, so that the rim of the funnel is drawn out into five curved edges in which the second radials rest. These are trapezoidal in form and convex at their proximal ends. This convexity is continued onwards as a ridge of tolerably uniform width, so that there is a flattened surface on either side of it, which increases in size towards the distal edge. This feature is continued on to the axillaries, which are wider than the second radials, and barely pentagonal in form. The medio-dorsal ridge enlarges (z00L, CHALL, EXP,—PART XxXx11.—1884.) li 31 242 THE VOYAGE OF H.M.S. CHALLENGER. about the centre of the joint, and is continued on to each of the arm-bases, where it disappears after about the first eight joints. These have sharp lateral edges where their flattened sides meet the dorsal surface. The first three or four are wider than long, their successors gradually becoming more cylindrical, but never much longer than wide and not over- lapping, so that the dorsal surface is smooth. The third joint is sometimes the only free one, all its successors being united in pairs; while in another case the fourth is free as well as the third, and also the seventh and tenth, the intermediate pairs being united. In a third variety three pairs after the third brachial are united, and the tenth is free again, while the remainder of the arm is normal. There are fifty jomts in an arm 30 mm. long (fide C. W. T.). The first pinnule is generally on the ninth, but sometimes not till the eleventh brachial. The pinnule attachment is near the end of the joint, so that the socket enters into the composition of the terminal face (Pl. VIla. fig. 21). The joints of the lower pinnules are not greatly larger than those of their successors. The disk is unprotected by plates. Colour, in spirit, white. About a dozen heads and several stems, some retaining the basals. Localities —Station 146. December 29, 1873; lat. 46° 46’ 8, long. 45° 31’ E.; 1375 fathoms ; Globigerina ooze ; bottom temperature 36°°6 F. Station 147. December 30, 1873; lat. 46° 16’ S., long. 48° 27’ E.; 1600 fathoms ; Diatom ooze ; bottom temperature 34°°2 F. | have no record respecting the number of individuals obtained at each Station. According to Sir Wyville Thomson" this species “ seems to be widely distributed ; we have detected fragments of it at at least six or seven Stations in the Atlantic and the Southern Sea.” Remarks.—The head of this species is readily distinguished from that of Bathycrinus campbellianus by the calyx being constricted at the basiradial suture, and not in the radial funnel above it; by the greater width of the arm-bases, and by the smoother dorsal surface of the arms. In the first of these characters it resembles Bathycrinus carpenteri, so far as can be made out from Danielssen and Koren’s figure; but it is much more robust than the northern species, in which the axillaries are considerably shorter than the second radials, while the lower stem-joints are relatively longer, and have much more expanded ends than those of Bathycrinus aldrichianus, in which the dice-box shape is less apparent. When the collection of Stalked Crinoids came into my hands, I found one bottle labelled “ Pterocrinus and Hyocrinus, Stations 146 and 147.” As I had never heard of the former genus, my curiosity was much excited, and it was with considerable disappointment that I found the contents of the bottle, besides Hyocrinus, to consist 1 Journ, Linn. Soc. Lond. (Zool.), vol, xiii. p. 51 (1876) 1878. REPORT ON THE CRINOIDEA. 243 principally of headless stems of Bathycrinus aldrichianus, some with and some without the basal ring at the summit. Mr. Murray tells me that one specimen of “ Pterocrinus” was presented to the University Museum at Sydney by Sir Wyville Thomson, which indicates that there must have been several duplicates of the type. The only explanation of these facts which I can think of is, that Sir Wyville had not then (1874) made up his mind that the relatively large individuals dredged at Stations 106, 146, and 147 were generically identical with the small and immature specimen which he had described two years previously as the type of the new genus Bathycrinus ; so that he was led to give them the MS. name Pterocrinus, which he afterwards abandoned (1876) in favour of Bathycrinus. Bathycrinus gracilis, Wyville Thomson, 1872 (Pl. VIIa. figs. 1-3 ; woodcut, fig. 16). 1872. Bathycrinus gracilis, Wyv. ‘Thoms., Proc. Roy. Soe. Edin., vol. vii, p. 772; The Depths of the Sea, pp. 450-454, fig. 75, 1873. Dimensions. Greatest length of stem (about forty joints), b F , 57°00 mm.! Longest stem-joints, ; : : ‘ : P : 2°50) ,, Length of head, . ; ; ; 3 : ; : 8:00 ,, Description of an Individual—sStem composed of about forty joints, of which the first ten or twelve are wider than high, increasing in thickness from above downwards. The following joints, at first cylindrical, increase rapidly in length, and acquire shghtly expanded ends, which become more and more marked in the lower joints, till the width of the end is 1 mm., twice the width of the shaft. The joints diminish in length towards the base of the stem, which ends in a small branching root. The basals are closely united into a smooth ring, the lower part of which is of the same size as the upper stem-joints, but expands gradually upwards.’ The radial pentagon above it expands more rapidly, so that there is a constriction at the basiradial suture, though not so marked as in Bathyeriius aldrichianus. The radials are strongly convex in the medio-dorsal line, but more flattened at the sides. Second radials nearly oblong, with a sharp median ridge and a slight hollow on either side of it. Axillaries shorter than the second radials and nearly oblong, and also marked by a sharp medio-dorsal ridge which forks about the middle of the joint, and is continued on to the three lowest brachials. There are only about twelve brachials in the arm, all of which are distinctly longer than wide, while the first two or three are scarcely wider than the rest, and have straight lateral edges like the radials. The later joints overlap rather sharply, so that the dorsal edge of the arm is serrate. The disk is unprotected by plates. Colour, in spirit, brownish-white. Locality — H.MLS. “ Porcupine,” 1869. Station 37. Lat. 47° 38’ N., long. 12° 8’ W.; 1 Sir Wyville gave this measurement as 90 mm., which was possibly a misprint for 60. 2 This expansion is not quite marked enough in the figure. 944 THE VOYAGE OF H.M.S. CHALLENGER. 2435 fathoms; Globigerina ooze; bottom temperature 36°°5 F. One nearly complete specimen, and one stem with the basal ring attached, but wanting the rest of the calyx. Fie. 16.—Bathycrinus gracilis, Wyville Thomson ; twice the natural size. Remarks.—The shortness of the arms and the absence of well grooved pinnules indicate that the single specimen of this elegant little species is not fully developed. Sir Wyville Thomson’ said that “ there is no trace of pinnules, and the arms resemble in character the pinnules of hizocrinus.” There are, however, little stumps on the terminal jomts of one or two of the arms which give them the appearance of bifurea- tion, just as at the growing point of the arms of a young Comatula or Pentacrinus ; and I see no reason to doubt that these stumps are the commencing pinnules. I have already pointed out that the arm- joints of Bathycrinus gracilis are united in pairs exactly like those of Bathycrinus aldri- chianus and Rhizocrinus, except that in the latter genus the union is a syzygial one ; and the supposed resemblance of the arms of Bathycrinus gracilis to the pinnules of Rhizo- crinus thus disappears. As might be expected from its geogra- phical position, Bathycrinus gracilis comes nearer to Bathycrinus carpentert than to either of the Challenger species. The lower stem-joints are strongly constricted with markedly expanded ends as in that type ; but the absence of orals, the well defined medio- dorsal keel on the radials and arm-bases, and the serrate condition of the arms are sufficient to distinguish it without difficulty. During the expedition of the “ Talisman ” in 1883” a few much mutilated specimens both of Bathycrinus gracilis and of Rhizocrinus rawsont (Democrinus parfaiti, Perrier) * The Depths of the Sea, p. 452, 1873. * Comptes rendus, t. xevii. p. 1392. See also H, Filhol, Voyage du “Talisman” in La Nature, No, 572, 17th May 1884, p. 391, REPORT ON THE CRINOIDBA. 245 were obtained off the Morocco coast at a depth of from 2000 to 2300 metres (1200 fathoms), “par le travers du cap Ghir et du cap Noun, d 120 milles environ de la céte.” This locality (in about lat. 30° N.) is the only one at which these two genera have been found associated. It is some 18° farther south than the position at which Bathy- crinus gracilis was first discovered by the “ Porcupine.” Genus Rhizocrinus, M. Sars, 1864 ; emend., P. H. Carpenter, 1884. Hugeniacrinites Apiocrinites Asterias ¢ Auctorum. Goniaster’ | 1846. Bourgueticrinus, dArchiac, Mém. Soe. géol. de France, sér. 2, t. ii. p. 200. 1847. Conocrinus, d’Orbigny, Cours élément. de Paléontol. et de Géol. stratigr.,’ t. i, Fase. 1, Paris, 1852, p. 147. 1850. Bourgueticrinus, @Archiac, Mém. Soc. géol. de France, sér. 2, t. iii, p. 418. 1850. Conocrinus, V’Orbigny, Prodrome de Paléontologie stratigraphique universelle des Animaux Mollusques et Rayonnées, t. 11., Paris, 1850, p. 332. 1852. Bouryucticrinus, Forbes, Monograph of the Echinodermata of the British Tertiaries, p. 36. 1864. Rhizocrinus, M. Sars, Forhandl. Vidensk. Selsk., p. 127. 1868. Bourgueticrinus, Pourtalés, Bull. Mus. Comp. Zodl., vol. i., No. 7, p. 128. 1868. Rhizocrinus, M. Sars, Mémoires pour servir 4 la connaissance des Crinoides vivants, p. 38. 1868. Rhizocrinus, W. B. Carpenter, Proc. Roy. Soc., p. 173. 1872. Rhizocrinus, Wyv. Thoms., Proc. Roy. Soe. Edin., vol. xvii. p. 770. 1874. Rhizocrinus, Pourtalts, Il. Cat. Mus, Comp. Zodl., No. 8, p. 27. 1874. Rhizocrinus, Manzoni, Bollett. d. R. Com. Geolog., p. 158. 1874. Rhizocrinus, Beyrich, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 666, 1875. Conocrinus, Meneghini, Atti dell. Soc. Tose. di Sci. Nat., vol. il. p. 46. 1875. Rhizocrinus, Meneghini, Ibid., p. 57. 1878. Conocrinus, de Loriol, Monographie des Crinoides fossiles de la Suisse, p. 190. 1880. Conoerinus, Zittel, Handbuch der Paleeontologie. Palieozvologie, Bd. 1. p. 391. 1882, Rhizocrinus, P. H. Carpenter, Bull. Mus. Comp. Zodl., vol. ix., No. 4, p. 173. 1883. Demoerinus, Perrier, Comptes rendus, t. xevi. p. 450. 1883. Rhizocrinus, P. H. Carpenter, Ann. and Mag. Nat. Hist., ser. 5, vol. x1, p. 336, 1883. 1884, Rhizocrinus, P. H. Carpenter, Proc. Roy. Soc. Edin., vol. xii. p. 356, The stem is composed of dice-box shaped joints, and terminates below in a spreading root, or bears a number of branching radicular cirri which come off irregularly, but not in definite verticils. Only a very few of the upper joints are thin and discoidal, and slightly wider than those below them. 1 The second volume of the Cours élémentaire bears the date 1852 on the title page ; but the genus is referred to as “Conocrinus, @’Orb., 1847.” This also appears in the Prodrome de Paléontologie published in 1850, in which work according to de Loriol, the genus was first established ; and I suspect that the date 1847, which is claimed hy d’Orbieny for his genus, merely has reference to an unpublished MS, 246 THE VOYAGE OF H.M.8. CHALLENGER. The calyx is higher than wide, generally much so. It consists of five basals and five radials, of which the former (in the recent species at least) are much the longer. Arms five, the joints united in pairs by syzygies, with pinnules on the epizygals only. The first pinnule on the epizygal of the third or fourth pair. The epizygal of the first pair has the sides of its ventral furrow produced upwards into strong processes which support the disk. The peristome is protected by five oral plates of variable size, but the remaining portions of the interpalmar areas are not plated. The ambulacra have covering plates, but no side plates. Remarks.—The name Riizocrinus was first employed in 1864 by the late M. Sars? to designate a singular new Crinoid which had been discovered by G. O. Sars in his dredgings among the Lofoten Islands; and it was the extreme interest of this type as a sort of degraded Apiocrinite which, through the intervention of Dr. Carpenter and the late Sir Wyville Thomson, led to the dredging cruise of H.M.S. “Lightning” in 1868. The results of this cruise, Rhizocrinus among them, were so remarkable that it was followed by the ‘‘ Porcupine” Expedition of 1869-70, and eventually by the voyage of the Challenger. It was the discovery of Rhizocrinus, therefore, and the interesting speculations to which this discovery gave rise, that led this country to take a foremost place in the work of deep-sea exploration. Meanwhile, however, Rhizocrinus had been rediscovered by the late Count Pourtales during the dredgings carried on by the U.S. Coast Survey in connection with the regular exploration of the Gulf Stream.? At that time (May 1868) Sars’s elaborate memoir on the type had not yet appeared, and the specimens dredged by Pourtales were described by him as ‘ undoubtedly belonging to the genus Bourgueticrinus, as defined by d’Orbigny,” a remark in which I entirely concur. He gave the provisional specific name “ Hotessiert” to his specimens, thinking that they might possibly be identical with Bourgueticrinus Hotessieri, VOxrb., stem-joints of which had been discovered in a recent breccia at Guadeloupe. After the appearance of Sars’s memoir, however, he recognised the identity of the Gulf Stream and of the Lofoten examples of the type, for which he adopted Sars’s name Phizocrinus lofotensis.* But he took a totally different view of the composition of the cup from that proposed by Sars, and in this respect, as will be pointed out immediately, he was decidedly in the right. For the large subradial portion of the summit, which was considered by Sars as an enlarged upper stem-joint, was shown by Pourtales to consist of five closely anchylosed basals. In the year 1875 the name Riizocrinus was doubtfully given by Meneghini* to some 1 Forhandl. Vidensk. Selsk., Christiania, 1864, p. 127. “Den 14de. October, Hr. Sars holdt et Foredrag om Pentacrinoide tilstanden af Comatula sarsit og om en ny levende Crinoide Rhizocrinus lofotensis.” * Contributions to the Fauna of the Gulf Stream at Great Depths, Bull. Mus. Comp. Zodl., vol. i., No. 7, p. 128. ®* List of the Crinoids obtained on the coasts of Florida and Cuba by the U.S. Coast Survey Gulf Stream Expedi- tions, in 1867, 1868, 1869, Ibid., No. 11, p. 357. 4 T Crinoidi Terziarii, Atti dell. Soc. Tose. di Sci. Nat., vol. ii. pp. 46, 50. REPORT ON THE CRINOIDEA. 247 stem- and arm-joints from the Italian Tertiaries, while he revived d’Orbigny’s name Conocrinus for d’Archiac’s Bourgueticrinus thorenti, after an interval of nearly twenty- five years. During this period, so far as I am aware, no palzontologist had taken any notice of @Orbigny’s attempt to differentiate Conocrinus from Bourgueticrinus. The first description" which he gave of the former genus (1847 2) ran as follows: “C’est un Bourgueticrinus ayant la tige comprimée, mais avec une seule série de pieces brachiales, sans pieces basales;” and he referred to it one unnamed species from the Suessonien (Lower Eocene). Three years later (1850) he spoke of Conocrinus as “genre voisin des Bourgueticrinus, mais sans pieces basales, comme les Hugeniacrinus;” and he mentioned Bourgueticrinus thorenti of dArchiac as belonging to this generic type.’ Meneghini has shown, however, that two species were described under this name by dArchiac. One is a much elongated type, first described in 1846, and probably that referred to by @VOrbigny in the following year; while the other that was not noticed till 1850, the year in which the second (first ?) description of Conocrinus appeared, is the Hugeniacrinus pyriforms of Minster. This species was not referred by d’Orbigny to his new genus Conocrinus, though undoubtedly belonging to it, as pointed out by Meneghini. But it was retained by him in Hugeniacrinus, so that the only species of Conocrinus recognised by @’Orbigny was the elongated Bourgueticrinus thorenti of @Archiac. The figures and descriptions of this type given by the latter author are somewhat incomplete. He had very few specimens, and was exceedingly doubtful about the position of the sutural lines, while they are certainly placed wrongly in his figure,’ according to which the second radials rest upon the sutures of the first. There is likewise no indication of an enlarge- ment of the uppermost stem-joints so as to form a “summit,” which is so characteristic of Bourgueticrinus ; while the presence of basals below the radials or “ piéces supérieures ” of Bourgueticrinus thorenti was distinctly described by d’Archiac, though he probably figured them incorrectly. Nevertheless, Conocrinus is a Bourgueticrinus without basals, and d’Archiac’s species in which basals are present is made the type of the genus ! Neither does it help in the differentiation of the two genera to speak of Conocrinus as a Bourgueticrinus with a compressed stem, when the stem of Bourgueticrinus itself is described as being compressed.* I find very considerable difficulty in comprehending what d’Orbigny really meant by Conocrinus. If it be “ voisin de Bourgueticrinus,” but also resembles Hugeniacrinus in the absence of basals, why was it omitted in his scheme of classification of the Apiocrinidee, published in 1858, from the fourth section comprising Eugenacrinus alone,’ and distinguished by having only “une série de piéces au sommet” ? On p. 95 he pointed out that no Tertiary species of Bourgueticrinus were then known, from which one may infer that the Tertiary fossils previously referred to this genus " Cours elémént. de Paléontol. et de Géol. stratigr., t. ii., 1852, p. 147. * Prodrome de Paléontologie stratigraphique universelle des Animaux Mollusques et Rayonnées, t. ii. p. 322. % Mém. Soc. géol. de France, ser. 2, t. ii. p. 200, pl. v. fig. 20. ' Cours élément, de Paléontol. et de Géol. stratigr., t. ii., 1852, p. 147. ® Hist. Nat. des Crinoides, p. 2. 248 THE VOYAGE OF H.M.S. CHALLENGER. really belonged to Conocrinus. But as he did not place the latter type among the Apiocrinidee together with Bourgueticrinus and Bugeniacrinus, it would seem that he had either abandoned it altogether, or else entirely misunderstood its real character and affinities ; and in the absence of figures or original specimens his account of it would be absolutely unintelligible. Rhizocrinus was first described by Sars in 1864,’ and more fully in 1868°; and though he was led to consider the anchylosed basals as a top stem-joint, this error was corrected by Pourtalés and myself before a fresh diagnosis of Conocrinus was given by de Loriol.? This indeed was only provisional, in default of better knowledge, and owing to Meneghini’s failure to find the interbasal sutures in a section through the lower part of the calyx,‘ just as in a recent Rhizocrinus or Bathycrinus (Pl. VIla. fig. 13), de Loriol was led to consider it probable that the basals “ n’existent pas et sont intimement soudées, de maniére 4 former comme une seule piece centro-dorsale.” He thus fell into exactly the same error as had been made by Sars and Ludwig respecting the recent Rhizocrinus lofotensis. Zittel,? however, who had satisfied himself regarding the presence of inter- basal sutures in Conocrinus pyriformis, recognised the identity of this genus with Rhizo- crinus, but did not adopt the latter name on the ground that ‘Nach den Regeln der Prioritiit gebiihrt dem Namen Conocrinus, d’Orb. die Prioritit, wenn gleich die Gattungs- diagnose @’Orbigny’s unyollstiindig und theilweise unrichtig ist.” It seems to me, however, that this is stretching the rules of priority to the widest possible limit, or even beyond it ; and that definitions which are incorrect, meaningless, and altogether incomplete have no claim whatever to recognition. Liitken remarked in 1864 that the distinction of Conocrinus from Bourgueticrinus was still a matter of uncertainty ; while d’Orbigny’s own countrymen Hébert and Munier-Chalmas did not adopt his generic name for the new type which they described as Bourgueticrinus suesst ; and although it was subsequently referred by de Loriol to Conocrinus, and carefully described, the genus Rhizocrinus had meanwhile become thoroughly well established and universally recognised by zoologists. Both Sars and de Loriol were in error as to the composition of the calyx in this type ; and a correct definition of Conocrinus was not given until the publication of Zittel’s Paleontology in 1879; while even as early as 1868,° and subsequently more fully in 1874,’ Pourtalés had correctly pointed out the characteristic features of Sars’s genus Rhizocrinus, especially as regards the presence of basals, which had been supposed to be either absent altogether, or else modified into a kind of rosette. According to Sars* “Ce qui est remarquable et characteristique pour la tige du Rhizocrinus, c’est son sommet 1 Forhandl. Vidensk. Selsk., p. 127. 2 Crinoides vivants, pp. 38, 39. 3 Swiss Crinoids, p. 191. * Loc. cit., p. 50. 5 Paleeontologie, p. 392. & Bull. Mus. Comp. Zodl., vol. i., No. 7, p. 129. 7 Ill. Cat. Mus. Comp. Zodl., No. 8, pp. 27, 28. * Crinoides vivants, p. 4. REPORT ON THE CRINOIDEA. 249 \ qui forme un grand évasement obconique ou caliciforme, ce qui donne 4 notre Crinoide de la ressemblance avec le genres fossiles Apiocrinus et Bourgueticrinus. Cette extremité nest done pas autre chose que le sommet de la tige qui s’élargit suecessivement.” Sars considered the summit therefore as an enlarged uppermost stem-joint analogous to the centro-dorsal of the Comatule. He was unable to resolve it into any component parts by treating it with alkalies; and it is consequently not surprising that he was led to regard the whole subradial portion of the calyx as composed of but one single piece. In fact he was never able to separate this piece from the radials or the radials from one another, the existence of these plates being only indicated on the outside of the calyx by very faint sutural lines, occasionally rendered more distinct by slight furrows. It never seems to have struck him, however, that there might be basal plates below the radials which were similarly, but more closely anchylosed ; and he was led to consider the basals as fused, lke those of Comatulz, into a kind of rosette. This circular plate (Pl. VIIla. figs. 6, 7; Pl. X. figs. 1, 4—br) “est située & Vintérieur dans l’espace central laissé en dedans de l’'anneau formé par l’adhésion des premiers radiales ;”! but Sars was unable to isolate it, owing to its very close adherence to the first radials. It has been pointed out that Rhizocrinus was dredged by Pourtalés in 1868 before he had heard of its discovery by Sars; and the condition of his specimens was fortunately such that he was able to describe the calyx as “‘ composed of a cycle of elongated basal (pelvic) pieces, followed by the much shorter first radials (costals) alternating with them. These pieces are all so intimately connected with each other that the sutures are seen with difficulty.”” This account seems to have escaped the notice of Sir Wyville Thomson; for in his description of the ‘‘ Porcupine ” Crinoids’ he stated that “in Rhzzocrinus the basal series of plates of the cup are not distinguishable. They are masked in a closed ring at the top of the stem.” He did not, however, entirely accept Sars’s view of the composi- tion of the calyx; for he went on to say that ‘‘ whether the ring be composed of the fused basals alone, or of an upper stem-joint with the basals within it forming a rosette as in the calyx of Antedon, is a question which can only be solved by a careful tracing of successive stages of development.” The relatively large specimens which were dredged by the “ Porcupine” in 862 fathoms off Cape Clear, show the interbasal sutures very clearly ; and though they were referred at the time to Rhizocrinus lofotensis, they really belong to the Caribbean species Rhizocrinus rawsoni, larger specimens of which were obtained by the “ Hassler” off Barbados in 1871, and described by Pourtalés in 1874. These, like the “ Porcupine” specimens and the Gulf Stream variety of Rhizocrinus lofotensis, also showed distinct interbasal sutures. Pourtalés was therefore led to dissent from Sars’s description of the calyx in this genus, and to repeat more emphatically his own previous statements concerning the existence of long but closely united basals.* 1 Crinoides vivants, p. 12. 2 Bull. Mus. Comp. Zool., vol. i. p. 129. 3 Proc. Roy. Soc. Edin., vol. vii., 1872, p. 770. 4 Mem. Mus. Comp. Zodl., No. 8, pp. 28, 29. (ZOOL. CHALL. EXP.—PART XXx1.—1884.) Ti 32 250 THE VOYAGE OF H.M.S. CHALLENGER. He found all the sutural lines in the calyx of both species, including those between the basals, to be “always plainly visible with a lens of moderate power ;” and he was there- fore naturally surprised at the description of the calyx which was given by Sars as the result of his study of the Norwegian specimens without interbasal sutures. In order to verify the truth of his analysis of the calyx, Pourtalés “forced a needle through the central hole of the calice of a Rhizocrinus lofotensis until it split. The fractures followed the joints between contiguous basals and between the latter and the first radials.” These important observations were entirely overlooked by Ludwig,’ who followed Sars in describing the subradial part of the calyx as an enlarged uppermost stem-joint. He took, however, another and more correct view of the circular plate which Sars had called the basal rosette (Pl. VIIa. figs. 6, 7; Pl. X. figs. 1, 4—br); for he regarded it as an unusual development of the calcareous network which occupies the central portion of the radial funnel in all Crinoids (compare Pl. XX. figs. 4, 6, 8) and surrounds the plexiform gland ascending from the chambered organ (Pl. XXIV. figs. 8, 9; Pl. LVIII. figs. 2, 3—rp). I have long ago expressed my acceptance’ of this modification of Sars’s views which we owe to Ludwig; but I could never quite reconcile myself to believe in the account which he gives of the basals of Rhizocrinus. Having disestablished the rosette of Sars, he found it necessary to seek elsewhere for the missing basals of this type; and here he fell into error, probably, I think, from a too exclusive reliance on his interpretation of sections through the decalcified calyx, without properly considering the characters of an isolated calyx minus its muscles and ligaments, such as was excellently figured by Sars in his Tab. u. fig. 43. A horizontal section through the upper part of the calyx (Pl. VIIIa. fig. 7), or a view of the calyx from above (Pl. X. figs. 1, 4), like those given by Sars, shows five (or six) apparently interradial pieces (mp) surrounding the so-called basal rosette (br), and occupying the interval between it and the large muscular and ligament-fossee on the sloping distal faces. Sars considered these pieces, and rightly so, as integral parts of the first radials. Ludwig’s sections, however, led him to believe that these pieces (Pl. VIIa. fig. 7, mp) “nicht radiiir, wie es nach der Sars’ schen Auffassung sein miisste, sondern interradiér legen, so niimlich, dass stets die Mittellinie eines jeden Stiickes B in die Trennungsebene zweier aneinanderstossender Radialien fallt.” * The interradial position of the pieces in question is, however, shown just as well in Sars’s figures as in those of Ludwig, who had no real grounds for stating that Sars had indicated their boundaries incorrectly. He considered that their interradial position precluded their being connected with the radials, and was therefore led to regard them as “ nach innen verschobene und ‘ Zeitschr. f. wiss. Zool., 1877, Bd. xxix. pp. 66-68. * On some points in the Anatomy of Pentacrinus and Rhizocrinus, Journ. Anat. and Physiol., 1877, vol. xii. p. 50. * The apparently interradial position of these pieces (mp) is more marked in Ludwig’s figures, where they are lettered B, owing to the semidiagrammatic character of these figures and the omission of the interarticular and dorsal ligaments. 7 1+) 4's Rey REPORT ON THE CRINOIDEA. 251 in ihrer urspriinglichen Gestalt verinderte Basalia.” He supposed these basals to be in a more embryonic condition than those forming the rosette of Comatula, and still remaining independent of one another as five isolated plates. But if this be the case one would surely expect to find the basals below the radials, and separating them from the top stem-joint as in the early stages of the Pentacrinoid larva of Comatulee and in the Stalked Crinoids generally. Ludwig, however, represents the supposed basals both in horizontal and in vertical sections as occupying a position above the radials, and forming the floor of the body- cavity some way above the chambered organ, with which the basals of Crinoids are always closely related. The position assigned by him to the basals of Rhizocrinus is one which I have no hesitation in describing as utterly impossible for these plates to occupy; and the dotted line inserted in his longitudinal section to mark the junction of the supposed basals with the first radials below them is purely imaginary. The same may be said of the lines that indicate an enveloping of the radials by upward processes of the supposed top stem-segment below them, which would cut off the radials altogether from the exterior of the calyx (compare wood- cut, fig. 17). That part of the calyx of Rhizo- erinus Which was considered by Ludwig to represent the embryonic basals altered in position, though not in nature, really belongs to the radials as was figured by Sars,’ who spoke of these plates as follows :—“étant tronquées dans leur partie intérieure, elles Fic. 17.—Diagrammatie vertical section through the calyx and disk of Rhizocrinus lofotensis ; x 75. Altered from Ludwig. The section is represented as passing through the middle line of aray on the left hand side, and as almost (but not quite) inter- radial on the right. A, axial cord of ray; a, primary inter- radial cord; B, basal tube; 0,, first brachial ; br, central calcareous plug, the basal rosette of Sars ; ca, fibrillar sheath round vascular axis of stem; ch, chambers of the quinque- locular organ ; ch’ their downward extension into the stem; c.co., portion of circular commissure formed by the secondary interradial cords ; fg, fore-gut ; G, mid-gut ; /, basiradial liga- ment; m, muscle; 7, oral ring of the ambulacral nervous system ; O, oral plate; Ry, radial ; re, rectum; st, top stem- joint ; T, tentacle ; v, central vessel of stem ; w, radial water- vessel ; wr, water-vascular ring ; x, plexiform gland. forment réunies un large anneau en laissant entre elles au milieu un espace arrondi ou un peu pentagone, rempli par la plaque ‘en rosette’ (fig. 42, 43, 7) mentionnée plus haut, reste probable des basales. Au point ot cette plaque rencontre le bout tronqué 1 Crinoides vivants, p. 14. 252 THE VOYAGE OF H.M.S. CHALLENGER. intérieur ou aminci des radiales, on remarque & chacun d’elles un petit trou rond, dow sort un sillon droit et lineaire (fig. 43, s), qui longe la ligne médiane de la face supérieure ou ventrale de chaque article et continue son parcours en remontant aussi de long du milieu de la face ventrale des radiales suivantes.” This interior truncated portion of the radials is really their ventral face; while the openings at its central portion are the ends of the axial radial furrows descending to the lower part of the calyx, and the furrows proceeding outwards from them are the ventral radial furrows (Pl. VIlla. fig. 7; Pl. X. figs. 1, 4—v7f) as described and figured by Sars, though Ludwig took them for interbasal sutures, Sars’s fig. 42 is particularly instructive in this respect, as four out of the five first brachials are i situ, and their ventral furrows are seen to be continued downwards on to the radials. The ventral interradial furrows which are so marked on the upper aspect of the calyx of many Comatule are absent or but slightly indicated in Rhizocrinus. Traces of them may be seen, however, in fig. 42 on Tab. 11. of Sars’s memoir. But the adjacent muscle- plates of every two contiguous radials are intimately fused and also slightly everted. Each is separated from its fellow on the same radial by a well marked, ventral radial furrow; and the united halves of the inner faces of adjacent radials thus assume somewhat the appearance of isolated interradial plates resting within and against the outer faces of the radials. Ludwig was thus led to consider them as basals, and so to fall into exactly the same kind of error with regard to their genetic relations as he attributed to Sars. I have nothing to add to his account of the chambered organ ; but his description of the cords which proceed from its fibrillar envelope needs a little modification. He has pointed out that they are interradial and not radial as described by Sars; but he says that they “ verbinden sich dann in den untersten Radialien durch Commissuren, ohne dass vorher eine Gabelung stattgefunden hitte.” Were this really the case, Rhizocrinus would be a much more anomalous form than it actually is. For in all other Crinoids, recent or fossil, in which this point has been worked out, with the exception of Bathycrinus, the primary interradial cords fork within the basals, and there are two openings either on the inner (Comatule) or on the under face (Pentacrinus) of each first radial (Pl. XII. figs. 11, 22; Pl. XX. fig. 9). Ludwig, however, figures these cords * in Rhizocrinus as single so long as they remain within the basals (top stem-joimt, Ludwig); and he believes them to fork in the suture between two radials, so that their branches would not enter the radials through their inner or under faces, but at their lower lateral angles. This is not quite the case, however, and it is probably to be explained by Ludwig's having used the section-method only, without attempting to separate the pieces of the calyx. This operation is one of no little difficulty, and some of the radials are sure to be fractured in the process ; but others separate from the basals along the sutural lines, and the arrangement of the canals can then be seen. The radials are comparatively low 1 Zeitschr. f. wiss. Zool., Bd. xxix. p. 72, 1877, Taf. vi. fig. 18 . REPORT ON THE CRINOIDEA., 253 externally, and their upper and under faces approach one another rather sharply, owing to the convexity of the upper surface of the basals, so that their inner ends are very thin. The centre of the funnel which they form is occupied by the compact plug of close cal- careous network which was mistaken by Sars for a basal rosette (Pl. VIIIa. fig. 7; Pl. X. figs. 1, 4—br). This is attached firmly to the inner ends of the radials, and comes away with them. It les on the top of the convex upper surface of the basals, the sloping sides of which are divided into fossee for the reception of the radials. Close to the inner end of each fossa is an elongated opening; and there is a similar one at the centre of the inner end of each radial ; but it is not exposed until after the removal of the central plug. Ludwig’s view, however, requires that there should be an opening at the inner lateral angle of each radial and none in the centre, as is really the case. The inference from this fact is that the primary interradial cords actually fork in the basals, and that the left branch of one fork, and the right branch of the next one pass out together through one of the elongated openings on the upper surface of the basal ring, which crosses the line of the — Fie, 18—Diagram of the distribution interbasal suture. I find this to be actually the case. Rhdzoerinus lofotenss. By Tusa R, radials ; 51, first brachials. Sections through the uppermost part of the basal ring, above the level of the chambered organ, clearly show the forking of the primary cords, though no interradial lines of suture are visible at these points, as should be the case on Ludwig’s theory of the composition of the calyx. At the same time I can readily understand how the use of the section-method alone led him to fall into this error. For owing to the convexity of the upper surface of the basals, a horizontal section through their central upper part might pass through the lowest and outer edge of the radial pentagon, and thus show interradial sutures, although the central portion of the section with the forking cords really belonged to the basals. The question is not a very important one; and but for my having been able to examine a dissected calyx, the exclusive use of the section-method would have led me to follow Ludwig’s description, ex- cept in one point. He does not seem to have noticed the presence of the intraradial commis- sures first described by himself in Antedon ; for he neither mentions them, nor introduces them in his diagram and figures. The special interradial commissures are of course absent, being unctionally replaced by the secondary interradial cords; but every two of these which converge within the substance of a radial are united by an intraradial commissure, just as they are in the Comatulz. This is clearly distinguishable in both the series of horizontal sections which I have cut through the calyx of Rhizocrinus lofotensis (Pl. VIIa. fig. 6, 2co). The distribution of the axial cords in the calyx of Rhizocrinus is thus somewhat different from that described by Ludwig, as will be seen if the accompanying woodcut (fig. 18) be compared with fig. 18 on Taf. vi. of his memoir. 254 THE VOYAGE OF H.M.S. CHALLENGER. There is another point in the anatomy of Rhizocrinus which is not brought out at all in the semidiagrammatic figure given by Ludwig (Taf. v. fig. 7). The second brachials (third radials of his nomenclature) are relatively much too small; but whether he pur- posely neglected the appearance presented by them, or whether they were really small and undeveloped in his specimens from reparation after injury, I cannot say. The whole of the visceral mass is occupied by the winding gut (Pl. VIIIa. fig. 8, G); so that the body-cavity is reduced to a minimum. But the outline of the visceral mass is not circular as represented by Ludwig, for a large diverticulum of the gut extends outwards between every two brachials. These approach one another over its outer end, so as to protect it, and it is supported on either side by one of the large processes bordering the ventral furrows of the brachials which were described and figured by Sars. This is well shown in the left hand portion of Pl. VIIa. fig. 8; while the right hand side shows the second brachials almost meeting one another over the interradial diverticulum of the rectum. The visceral mass and third radials of Bathycrinus present the same characters as seen in Pl. VII. fig. 4a, and Pl. VIIb. fig. 7, the first of which shows the great pro- cesses on the ventral face of the axillary radial. It would be interesting to determine whether the axillaries of Bourgueticrinus present similar processes. The syzygies of Rhizocrinus, at any rate in the lower parts of the arms, are slightly different in character from those of other Crinoids. The apposed faces are not completely striated as in Comatula, or even partially so as in Pentacrinus (Pl. XII. figs. 7, 10, 18, 21; Pl. XXI. figs. 1d, 2d, 5a; Pl. XXX. figs. 20, 21), as Sars has already pointed out in the case of Rhizocrinus lofotensis.. Neither, however, are they perfectly simple, as is sometimes the case in Pentacrinus (Pl. XXVI. figs. 5, 8; Pl. XXXVII. figs. 3, 4; Pl. L. figs. 6, 7, 12, 13). For there is an indistinct vertical ridge around the opening of the central canal of the hypozygal, resembling that of a bifascial articulation ; and this forks at its lower end so as to enclose a somewhat triangular pit into which there fits a corresponding process of the epizygal. The hypozygal faces which I have found to show this character most clearly are those of the first brachials of a Rhizocrinus rawson from the Azores (PI. X. fig. 8). It is less visible in the corresponding joints of the Havana _ specimen (Pl. X. fig. 6). It likewise appears, though less distinctly, on the first brachials of a specimen of Rhizocrinus lofotensis from Havana (Pl. X. fig. 1). Sars makes no reference to it in his description of this species, but the pit on the distal face of the first brachial is clearly shown in his Tab. iii. fig. 58, and also in a dorsal view (fig. 54). The backward projection on the second brachial of Rhizocrinus rawsoni is represented in Pl. X. fig. 19; while figs. 17 and 18 show the apposed faces of a syzygial union farther out on the arms, the backward process of the epizygal and the corresponding pit on the hypozygal being very distinct. A curious peculiarity which is presented by one of the Azores specimens of Rhizocrinus 1 Crinoides vivants, pp. 15, 22. REPORT ON THE CRINOIDEA. 255 rawsoni is shown in PI. X. fig. 8. The adjacent edges of two contiguous first brachials send out short processes which meet one another and rest upon the fused muscle-plates of the two radials beneath, so as to cut off a tubular space from the body-cavity. I have found nothing like this in either of the other specimens, which have lost all the visceral mass together with the second and following brachials (Pl. X. fig. 6). The structure in question may be only accidental, or on the other hand it may perhaps have some relation to the anal tube. The presence of the syzygy between the first and second brachials of Riizocrinus renders it a matter of some difficulty to obtain entire specimens, especially of Rhizocrinus rawsoni. For the arms break away at this point, carrying with them the entire visceral mass. This is the condition of the individuals represented in Pl. X. figs. 1, 6, 8; while fig. 20 shows the arm-bases from the second brachial onwards, and the visceral mass which they enclose. Two of them have been removed so as to expose the simple digestive apparatus, with the oral plates around the mouth and a relatively long anal tube. The position of the genital glands in the pinnules borne by the epizygals of the third syzygial pair is also well shown. I am strongly inclined to believe that the loss of the visceral mass and arm-bases may occur and be made good during life. This appears to have taken place in the Havana specimen represented in Pl. X. fig. 7. Small oral plates are visible in the centre at a point much below their usual level, which is seen in fig. 20; while the second brachials are so much smaller than the first that the difference is evidently due to fracture and reparation, just as so often occurs on the arms of Pentacrinus and Comatula. But in this case all the arms broke away together, carrying the visceral mass with them, so that a new one had to be developed within the ring of regenerated arms. Not much is to be seen of it, however, except the oral plates, the replacement of which is a point of considerable interest. It has long been suspected that eviscerated Comatule have the power of restoring their disks; but this is the first instance of the kind that I have met with in a Stalked Crinoid. Owing to the fact that the ring of anchylosed basals in Rhizocrinus was at first regarded as an enlarged top stem-joint, the affinity between this genus and Bourgueti- erinus has been supposed to be much closer than can be admitted in the light of our present knowledge. For in some respects Rhizocrinus stands farther from Bourgueti- erinus than even Bathycrinus does. The fossil genus Mesocrinus,’ although still but imperfectly known, is probably nearer Bourgueticrinus than either of these two genera. But it appears to differ from them in the smaller size of the upper stern-joints, a point in which it resembles both Rhizocrinus and Bathycrinus. In the two best known species 1 See Marshall, Quart. Journ. Micr. Sci., 1884, vol. xxiv., N. S., pp. 525, 526. 2 On Two New Crinoids from the Upper Chalk of Southern Sweden, Quart. Journ. Geol. Soc., vol. xxxvii. p. 130, pl. vi. figs. 1-7. tt SAN? ae we 256 THE VOYAGE OF H.M.S. CHALLENGER. of Bourgueticrinus (ellipticus and e@qualis) the uppermost part of the stem is formed of joints of an altogether different character from those which are to be found lower down. The latter are wider than high, with articular faces of a pointed oval shape, the two diameters of the oval being very unequal in length. Towards the upper part of the stem this inequality disappears, and the joints become more discoidal, though never thin and lamellar, as in the highest part of the stem of Rhizocrinus and Bathycrinus (Pl. VIL figs. 2,11; Pl. VIlla. fig. 1; Pl. IX. figs. 1-3; Pl. X. fig. 2). Above these discoidal joints, however, the stem gradually enlarges, and from two to four of the uppermost joints on which the calyx rests are of great relative size, both height and diameter being considerable. Sometimes the top joint is highest and sometimes the one below it; but at any rate one or more of these large upper joints remain united with the calyx to form the so-called summit. The upper stem-joints of Apiocrinus are not as a rule much higher than those below them; but the diameter often increases considerably from a point in the stem a little way below the calyx, so that a tolerably large number of joints enters into the composition of the summit. In species like Apiocrinus crassus, Apiocrinus magnificus, and Apiocrinus murchisonianus, however, there is scarcely any enlargement of the stem below the calyx, the uppermost joints, except the highest one on which the basals rest, being but little if at all larger than those below them. The same variations appear in Millericrinus. Millericrinus nodotianus has high upper joints, while those of Millericrinus simplex are thin and discoidal externally ; though the upper- most joint has a large synosteal surface for the reception of the basals which rest upon it. It seems to me very probable, therefore, that the existence of similar variations will have to be admitted in Bowrgueticrinus; though on the other hand a revision of the genus may result in the transfer of all the species without enlarged upper stem-joints to Rhizocrinus or Mesocrinus, especially if the articular faces of their radials are well developed and not reduced to a minimum as in Bourgueticrinus equalis. But I am quite prepared to have to abandon Mesocrinus as a distinct generic type, and to modify the descriptions of Bouwrgueticrinus which are given by paleontologists so as to include in this genus the two species Mesocrinus fishert and Mesocrinus suedicus, on which the genus Mesocrinus was based. Even then, however, Apiocrinus and Bourgueticrinus would differ from Rhizocrinus and Bathycrinus in the character of the upper stem-joimt. In the two genera last mentioned, as in Pentacrinus, this joint is the youngest and smallest of the whole stem, being merely a delicate film of calcareous reticulation which is received into and concealed by the curved under surface of the basals. In Apioerinus, however, and in Bourgueti- crinus this upper joint, though perhaps small externally, is large internally and supports the basals in five large fossze on its surface. As it closes the calyx below and really belongs thereto, de Loriol’ has called it the 1 Swiss Crinoids, p. 6; Paléont. Frang., loc. cit., p. 19. REPORT ON THE CRINOIDEA. 257 “article basal.” It is entirely undeveloped in Rhizocrinus, though this type shows a slight decrease in the width of the stem a little below the cup, before the commencement of the gradual downward enlargement, just as is so much more marked in Bourgueticrinus. There are certain other points in which the two recent species of Rhizocrinus, together with some fossil ones, differ very markedly from Bourgueticrinus; and although these differences hold good for some of the fossil species of Rhizocrinus, it is difficult to say how far this may be the case with others, owing to their imperfect state of preservation. In the first place, the basals are of great relative height, often five or six times that of the radials, and they occupy much the larger part of the exterior of the calyx; while the lower stem-joints are usually longer than wide. If they bear radicular cirri these come off somewhat irregularly from near the ends of the joints, but their sockets are not verticillate, nor are they ever formed by portions of two apposed joints, as is often the case in Bourgueticrinus and Mesocrinus. Rhizocrinus lofotensis and Rhizocrinus rawsont show these characters very well (Pl. IX. fig. 1; Pl. X. fig. 15). The latter has the longer basals, but its stem-joints, though longer than wide, are not so markedly so as in Rhizocrinus lofotensis. The same is the case with the stem-joints of the so-called Bourgueticrinus londinensis, which is really a well-defined Rhizocrinus ; while in those of Conocrinus (Rhizocrinus) suessi and Conocrinus pyriformis the width of the articular faces is more nearly equal to the length of the joint. In all these species the basals are longer than the radials, though not greatly so; but in Bourgueticrinus (Rhizocrinus) thorenti they are very long, as in the recent Rhizocrinus rawsoni, while the stem-joints resemble those of Rhizocrinus lofotensis in their proportions. Owing to the shape of the basals, the calyx of Rhizocrinus is usually cylindrical or obeonical, and though it expands gradually upwards it is nowhere very greatly wider than the stem, as is the case in Bowrgueticrinus. In Conocrinus suessi and in Conocrinus pyriformis, and perhaps also in Conocrinus seguenzai, it takes on amore ovoid form ; while in Rhizocrinus rawsoni and Rhizocrinus thorenti it may be very considerably elongated. So far as I-am aware, no true Rhizocrinus has been obtained from any formation lower than the Eocene. Quenstedt' figures some moderately elongated stem-joints of Apiocrinus constrictus from the White Chalk of Riigen. But in the absence of a calyx it is almost impossible to determine these generically, owing to the rarity of the association of calyces and stem-joints at the same spot. The same is the case with regard to the Jurassic species of Bourgueticrinus, e.g., Bourgueticrinus ooliticus from the Bradford Clay, which is perhaps referable to Thiollericrinus as suggested by de Loriol. The distinguished Swiss paleontologist has also described a fossil from the Cretaceous of Alabama, U.S., as Bourgueticrinus alabamensis.? It consists only of the basal cone which “supports the calyx, and which is composed of several enlarging segments of the 1 Encriniden, Tab. 104, figs. 64-66. 2 Description of a New Species of Bourgueticrinus, Journ. Cincinn. Soc. Nat. Hist., vol. v. p. 118, pl. v. fig. 1. (ZOOL, CHALL, EXP,—PART XXXII,—1884,) Ti 33 258 THE VOYAGE OF H.M.S. CHALLENGER. column surmounted by the basal plates.” His figure shows five of these uppermost stem- joints, which are all low and discoidal ; and it consequently appears to me that the fossil should be referred to Rhizocrinus rather than to Bourgueticrinus. If this be the ease, and its horizon really Cretaceous, this species is of interest as beimg the only known instance of a Cretaceous Rhizocrinus. On the other hand, Bourgueticrinus although abundant in Cretaceous deposits, is not certainly known to occur in any Tertiary formation. Some of the types described under * this generic name from the Italian Tertiaries have been referred to Conocrinus by Meneghini and others. Among these is the Apiocrinus cornutus of Schafhautl, which was doubtfully referred to Bourgueticrinus by Meneghini ;* though Zittel,’ while describ- ing its calyx as “niedrig schiisselformig,” spoke of it as Conocrinus cornutus. 1 have been enabled by the kindness of Prof. Zittel to examine the calyx of this species for myself; and I was interested in finding its shape to be very like that of a singular bowl- shaped calyx from the London Clay which is preserved in the Natural History Museum. This has relatively large radials and low basals. Ido not see how it can possibly be placed in the same genus as Conocrinus thorenti or Rhizocrinus rawsom with their elongated calyces mainly formed by the long basals ; and I think that it will be necessary to establish a new genus for the reception of these two species, to which others will probably be added when the calyces are found corresponding to some of the other Tertiary stem-joints that are now referred to Bourgueticrinus in default of further evidence, e.g., Bourgueticrinus didymus, Schaur. Rhizocrinus was supposed by Pourtalés to have a considerable resemblance to the genus Belemnocrinus from the Burlington limestone of Iowa and Illinois. Wachsmuth and Springer? have spoken of this resemblance as being very close and interesting, and stated that “the most important difference, and indeed the only essential distinction between these genera in their external structure, is found in the solid proboscis and covered dome of Belemnocrinus.” It appears to me, however, that the American authors lay too much stress on the fact that the calyx is formed in both genera of five long and narrow basals, and that they have overlooked other and more important structural characters. In the first place the stems of the two types are totally different. That of Belemnocrinus is pentagonal, consisting of short joimts with crenu- lated faces; while the stem-joints of Rhizocrinus are elongated and more or less dice- box shaped, with the well known, enlarged and elliptical ends. Stem-joints articulated like those of Rhizocrinus do indeed occur in the Palsozoie Platycrinus, and under these circumstances we may fairly expect that any genetic relationship between Belemnocrinus and Rhizocrinus would have manifested itself in this character. But the stem of Belemnocrinus, at any rate of Belemnocrinus florifer, seems to have borne successive 1 Atti della Soc. Tosc. di Sci. Nat., vol. ii. p. 53. 2 Paleontologie, Bd. i. p. 392. 8 Revision of the genus Belemnocrinus, and description of two new Species, Amer. Journ. Sci. and Arts, 1877, vol, exiii, p. 255. REPORT ON THE CRINOIDEA. 259 verticils of five cirri, just like that of a recent Pentacrinus; and this is a much more important morphological resemblance than the length of the basal plates. Then again the radials of Rhizocrinus are all in close lateral contact, while Belemno- crinus has an anal plate intervening between two of the radials and resting on a basal. It supports a heavy proboscis on its upper face, while Rhizocrinus has a disk protected by five insignificant oral plates. The arms of Belemnocrinus are ten in number, while Rhizocrinus has only five. This, however, is unimportant; but the arms of Belemno- crinus bear two rows of pinnules alternately, while in some species these primary pinnules bear alternating secondary ones, a condition totally unknown in any Neocrinoid. Altogether, therefore, the structure of the arms of Belemnocrinus is very different from that of Rhizocrinus, in which every joint has a syzygial surface at one of its ends ; though it must be admitted that syzygies are plentiful in the arms of Belemnocrinus, as there are some species, e.g., Belemnocrinus pourtalesi, in which “ throughout the greater portion of the arms every alternate joint is a syzygium.” This character, however, and the length of the basals are of minor importance compared to the intercalation of the anal plate in the calyx and the nature of the articulation between the stem-joints, so that I cannot in any way regard Belemnocrinus as an ancestral form of Rhizocrinus. 1. Rhizocrinus lofotensis, M. Sars, 1864 (Pl. VIIa. figs. 6-8; Pl. IX. figs. 1, 2; Ply x foes, 2). 1864. Rhizocrinus lofotensis, M. Sars, Forhandl. Vidensk. Selsk., p. 127. 1868. Rhizocrinus lofotensis, M. Sars, Mémoires pour servir 4 la connaissance des Crinoides vivants, p. 38. 1868. Bourgueticrinus Hotessiert, Pourtalés, Bull. Mus. Comp. Zodl., vol. i., No. 7, p. 128. 1872. Rhizocrinus lofotensis, Wyv. Thoms. (pars), Proc. Roy. Soc. Edin., vol. vii. p. 770; The Depths of the Sea, 1873, pp. 447, 450. 1874. Rhizocrinus lofotensis, Pourtalés, Ill. Cat. Mus. Comp. Zodl., vol. iv., No. 8, p. 28. 1882. Rhizocrinus lofotensis, P. H. Carpenter, Bull. Mus. Comp. Zoél., vol. x., No. 4, p. 173. 1884. Rhizocrinus lofotensis, P. H. Carpenter, Proc. Roy. Soc. Edin., vol. xii. p. 356. Dimensions. Greatest length of stem (Pourtalés), ; C : : 5 inches. Greatest length of stem (Sars), sixty-seven oe (2) : . : . 70mm. Greatest length of entire specimen (Sars), 5 : ; ‘ Sak OO) ass Greatest length of arm, about thirty-five joints (Sars), . : : st gl, Stem slender, bearing branching radicular cirri on its lower part, and ending below in a more or less spreading root. The cirri come off near the terminal faces of the lower joints at the ends of their longer axes. The joints are markedly dicebox-shaped, and nearly three times as long as wide. The calyx is smooth and obconical, of somewhat variable proportions. Basals two or 260 THE VOYAGE OF H.M.S. CHALLENGER. three times the height of the radials, and closely fused, so that their sutures are rarely visible. Radials short and quadrate, with concave upper and convex lower edges ; usually five in number, but sometimes four, six, or seven. Arms of from thirty to forty joints, which are united in pairs by syzygies. First brachials flattened, and quite free laterally, square or slightly longer than broad. The second similar, but somewhat shorter. The third still shorter and trapezoidal, so that the arm narrows considerably at this point. The remaining joints as long or a little longer than wide, and more convex than the preceding ones. The epizygals which bear the pinnules are rather longer than the hypozygals and irregularly pentagonal, as the pinnule facets are large relatively to the length of the joints. The first pinnule is on the eighth brachial or fourth epizygal. The two lowest pinnule-joints are somewhat trapezoidal in shape, and in contact bytheir broader ends. The remaining joints have a medio-dorsal keel and flattened sides, with the edge of the ventral furrow produced upwards into broad thin plates, especially in the third and following joints. The peristome is at the level of the second brachial, and protected by five linguiform oral plates which occupy the central ends of the interpalmar areas. Colour, in spirit, brownish-white or greyish-white. Localities.—The Lofoten Islands, 80 to 300 fathoms ; the J osephine Bank. H.M.S “ Lightning,” 1868. Station 12. Lat. 59° 36’ N., long. 7° 20’ W.; 530 fathoms; Globigerina ooze; bottom temperature, 47°°3 F. Three small specimens without arms. Station 16. Lat. 61° 2’ N., long. 12° 4’ W.; 650 fathoms; Globigerina ooze. Two small specimens without arms. Stem-fragments were occasionally found in the “cold area” during the cruises of the “Lightning” and “ Porcupine.” H.M.S. Challenger. Station 244. March 25, 1873, off Culebra Island; lat. 18° 43’ N long. 65° 5’ W.; 625 fathoms; Pteropod ooze. Two specimens. Station 1220. September 10, 1873, off Barra Grande ; lat. 9° 10’S., long. 34° 49’ W 400 fathoms; red mud. ‘Two specimens. Station 323. February 28, 1876; lat. 35° 39’S., long. 50° 47’ W.; 1900 fathoms ; blue mud; bottom temperature 33°°1F. The occurrence of a stem-fragment here is recorded in the Station-book, but it has not come into my hands, and I am therefore unable to speak positively about it. H.MLS. “Knight Errant,” 1880. Station 5. Lat. 59° 26’ N., long. 7° 19’ W.; 515 fathoms; mud; bottom temperature, 45°°4 F. Two young specimens without arms. Station 6. Lat. 59° 37’ N., long. 7° 19’ W.; 530 fathoms; grey mud; bottom temperature, 46°°5 F. A fragment only. : Rhizocrinus lofotensis has also been dredged several times by the surveying ships of the U. S. Coast Survey, as recorded in the following list. sh) +3 SS. “Bibb,” May 4, 1868, off the Samboes; 237 fathoms. May 11, 1868, off Sand Key ; 248 and 306 fathoms. March 4, 1869, off Cojima, near Havana; 450 fathoms; and several times at lesser depths. pe REPORT ON THE CRINOIDEA. 261 SS. “Blake,” 1877-78. No. 29, lat. 24° 36’ N., long. 84° 5’ W.; 955 fathoms; bottom temperature, 394°. No. 35, lat. 25° 5’ 46” N., long. 88° 58’ W.; 804 fathoms; bottom temperature, 403°. No. 43, lat. 24° 8’ N., long. 82° 51’ W.; 339 fathoms; bottom temperature, 40°. No. 44, lat. 25° 33’ N., long. 84° 35’ W.; 539 fathoms; bottom temperature, 394°. No, 56, off Havana, lat. 22° 9’ N., long. 82° 21' 30” W.; 175 fathoms. 1878-79. No. 238, off Grenadines, 127 fathoms; fine coral sand; bottom temperature, 56°. No. 248, off Grenada ; 161 fathoms; fine grey ooze; temperature, 534°. No. 259, off Grenada; 159 fathoms; bottom temperature, 534°. No. 274, off Barbados ; 209 fathoms ; fine sand and ooze ; bottom temperature, 534°. 1880. No. 306, lat. 41° 32’ 50” N., long. 65° 55’ W.; 524 fathoms. U. S. Fish Commission, 1882. No. 1124, 8.S.E. off Nantucket ; 640 fathoms. Remarks.—An elaborate account of this well-known species has already been given by Sars, and I have little to say about it except on one or two points. (1) The sub- radial portion of the summit is not formed by the top stem-joint as supposed by him, but it consists of anchylosed basals, as was originally described by Pourtalés.* (2) I have also followed Pourtalés in considering the two joints immediately above the radials as the two lowest brachials, and not as the second and third (axillary) radials, as they have been called by Sars, Ludwig, and Wyville Thomson. No matter what the number of arms of a Crinoid, the so-called second and third radials are morphologically brachials, as I have already pointed out (ante, pp. 47, 48); and though it is convenient for descriptive purposes to speak of the successive divisions of the rays as radials, distichals, and palmars, I see no advantage whatever in calling the two lowest arm-joints of a five-armed Crinoid the second and axillary radials. That they are homologous with the second and third radials of Comatula and Pentacrinus is undisputed, but these are fundamentally brachials ; and as it is the distinctive character of an axillary joint that it should bear two arms (or arm-divisions) on its distal face, the use of the term “axillary” in the case of a five-armed Crinoid is misleading and unnecessary. There is another point in Sars’s description that I would just notice. On p. 23 he says distinctly that the covering plates of the ambulacra occur “ sur le disque, aussi bien que dans toute la longueur des bras et des pinnules.” But there is no sign of them in either of his figures of the disk (Tab. iv. figs. 85, 86, 89). In fact, in fig. 85 no covering plates are represented at all, though the food-groove is shown as far as the distal part of the second brachial; while in the other two figures the first covering plate is shown resting on the distal part of the second, or the lower part of the third brachial. The form of the calyx in this species varies very considerably ; for it is nearly hemispherical in some specimens and much elongated in others. These last have the best developed arms; and to some extent, therefore, the forms with a low and wide cup must be regarded as premature. But differences of development will not entirely account for the variation, as the calyx of a young specimen found by Sars! is distinctly higher (longer) than broad. 1 Crinoides vivants, Tab. iv. fig. 95. 262 THE VOYAGE OF H.M.S. CHALLENGER. ‘2. Rhizocrinus rawsont, Pourtalés, 1874 (Pl. IX. figs. 3-5; Pl. X. figs. 3-20; Pl. LIIL. figs. 7, 8; woodcut, fig. 19). 1872. Rhizocrinus lofotensis, Wyv. Thoms. (pars), Proc. Roy. Soc. Edin., vol. vii. p. 770; The Depths of the Sea, 1873, p. 450. 1874. Rhizocrinus Rawsonii, Pourtalés, Ill. Cat. Mus. Comp. Zodl., vol. iv., No. 8, p. 27. 1882. Rhizocrinus rawsoni, P. H. Carpenter, Bull. Mus. Comp. Zodl., vol. x., No. 4, p. 173. 1883. Democrinus Parfaiti, Perrier, Comptes rendus, t. xcvi., No. 7, p. 450. 1883. Rhizocrinus rawsoni, P. H. Carpenter, Ann. and Mag. Nat. Hist., ser. 5, vol. xi. p. 335. 1884. Rhizocrinus rawsoni, P. H. Carpenter, Proc. Roy. Soc. Edin., vol. xi. p. 357. Dimensions.* Greatest length of entire specimen (Captain Cole), . - ; - 190°0 mm. Greatest length of stem, sixty-eight joints (“ Blake” specimen), : TSO op Greatest length of calyx (“Blake”), . ; - : 3 : OHO" 55 Greatest diameter of same calyx, 5 ; - : . : TED ee Greatest length of arm, sixty double joints (Captain Cole), . ‘ a OP Stem robust, bearing few radicular cirri on its lower part, but ending below in a long spreading root which attaches itself at intervals. The joints are from once and a half to twice (rare) as long as broad, and tolerably cylindrical or barrel-shaped in outline. The planes of the articular ridges at their ends cross one another, but the ends are not much expanded, so that the dice-box shape is but little marked. The calyx is very variable in form, sometimes long and slender, sometimes short and broad. The expansion from below upwards is rarely quite uniform, and there is often a more or less defined constriction about the level of the basiradial suture. The basals are separated by distinct sutures, and are generally four or more times the height of the radials, which are five in number, and more or less distinctly pentagonal. The arms may have one hundred and twenty joints united in pairs by syzygy. The first brachials are flattened, quite free laterally, and wider than long. The second are more nearly square, and the next four shorter but of about the same width, the last one (or the epizygal of the third syzygial pair) often bearing the first pimnule. The following hypozygal joints are obliquely oblong; while the epizygals are more irregular in shape, and sometimes almost triangular, so as to look like axillaries. The first pinnule is generally on the sixth or eighth brachial, but sometimes not till the fourteenth. The two lowest joimts of the basal pinnules are broader than their successors, which are elongated and of gradually diminishing width. The peristome is about at the level of the sixth brachial, and is protected by small oral plates. Colour, in spirit, brownish-white or greyish-white. Localities.—H.M.S. “ Porcupine,” 1869. Station 42. Off Cape Clear, lat. 49° 12’ N., ? Some other measurements of particular details will be found on p. 265, where also reference is made to the unusually elongated calyx of the individuals dredged by the “ Trayailleur.” REPORT ON THE CRINOIDEA. 263 long. 12° 52’ W.; 862 fathoms; bottom temperature, 39°'7 F.; ooze with sand and shells. Two armless specimens. Station 43. Lat. 50° 1’ N., long. 12° 26’ W.; 1207 fathoms ; bottom temperature, 37°°7 F.; Globigerina ooze. Two young specimens, one without arms. H.M.S. Challenger. Station 76. July 3, 1873; south of Terceira (Azores), lat. 38° 11’ N., long. 27° 9’ W.; 900 fathoms; Pteropod ooze; bottom temperature, 40° F. Three specimens without arms. Rhizocrinus rawsoni has also been dredged by the surveying ships of the U. 8. Coast Survey, as recorded in the following list. SS. “Hassler,” December 29-30, 1871. Off Sandy Bay, Barbados; 100 fathoms. SS. “Blake,” 1877-78. No. 32, off Havana; lat. 23° 32’ N., long. 88° 5’ W. ; 95 to 175 fathoms. 1878-79. No. 155, off Montserrat; 88 fathoms; bottom temperature, 69° F. No. 166, off Guadeloupe; 15C fathoms ; bottom temperature, 593°. No. 177, off Dominica; 118 fathoms; bottom temperature, 65° fine sand and broken shells. No. 211, off Martinique ; 357 fathoms; fine yellow sand and broken shells, No. 273, off Barbados; 103 fathoms; bottom temperature, 593°; coral and broken shells, yellow. No. 277, off Barbados; 106 fathoms; bottom temperature, 58°; hard rocky bottom. No. 290, off Barbados; 73 fathoms ; bottom temperature, 70°; coarse coral sand and broken shells. No. 296, off Barbados; 84 fathoms ; bottom temperature, 614° ; hard bottom. No. 297, off Barbados; 123 fathoms ; bottom temperature, 564° ; calcareous stones. Telegraph steamer “Investigator,” Captain E. Cole. Saba Bank ; 200 fathoms. Fifteen miles N. by E. from ~Panama; 300 fathoms. The French steamer “ Travailleur,” 1882,! “1900m. de profondeur sur les cétes du Maroc, par le travers du cap Blane.” Also the “Talisman,” 1883,2 “ Par le travers du cap Ghir et du cap Noun, 4 120 milles environ de la céte,” 2000 to 2300 metres. Remarks.—The first examples of this type which were actually obtained were those dredged by the “ Porcupine” in 1869, at depths of 862 and 1207 fathoms off Cape Clear (Stations 42 and 43). They were, however, considered by Sir Wyville Thomson merely as unusually large specimens of Rhizocrinus lofotensis; and the correctness of this identification would perhaps not have been doubted, but for the discovery in 1871 by the U. S. Coast Survey steamer “ Hassler” of some fine individuals, which Mr. Pourtales recognised as specifically distinct from Rhizocrinus lofotensis. Two specimens which were obtained by the Challenger in 900 fathoms among the Azores (Station 76) were at first referred to Rhizocrinus lofotensis; but having compared them with the Rhizocrinus rawsont of the Caribbean Sea, I find that they likewise belong to that species. It is generally larger and more robust than Rhizocrinus lofotensis, and the calyx, instead of being regularly obconical, is extremely variable in form, as will be seen subsequently. All the specimens that I have seen have been regularly pentamerous, while in Rhizocrinus lofotensis the number of radials is not unfrequently four or six (Pl. VIIIa. fig. 7), and may reach seven. Those of Rhizocrinus rawsont are generally shorter 1 Comptes rendus, t. xcvi. p. 459. 2 [bid., t. xevii. p. 1392, 264 THE VOYAGE OF H.M.S. CHALLENGER. relatively to their width, than in Fhizocrinus lofotensis, while the third brachial is oblong and not trapezoidal, so that there is no sudden narrowing of the arm at the syzygy between the third and fourth brachials. The shape of the arm-joints too, especially of those which bear pinnules, is not the same in the two species; while the pinnules them- selves, and more particularly those on the proximal parts of the arms, differ very considerably in appearance, those of Rhizocrinus rawsoni having broad lower joints. The visceral mass of Rhizocrinus lofotensis is relatively lower than that of Rhizocrinus rawsoni, in which it is supported by the first six brachials (Pl. X. fig. 20); while in Rhizocrinus lofotensis the ambulacra leave the peristome at the level of the second brachials, on to which they pass. The stem-joints of Rhizocrinus rawsoni are relatively shorter and thicker than those of Rhizocrinus lofotensis, in which the length is three times the width, and the radicular cirri at the base of the stem are much more numerous in this species than in Rhizocrinus rawsom. In fact there are no radicular cirri whatever in one of the Challenger specimens of Rhizocrinus rawsoni, and only two, borne upon the first joint above the root, in one of those dredged by the ‘‘ Porcupine.” In correspondence with this, the root of Rhizocrinus rawsont is more like that of Bathycrinus, the lowest stem-joint giving rise to three or more stout branches, which themselves eventually subdivide and bear radicular cirri (Pl. X. fig. 15). This condition appears to be comparatively rare in Phizo- crinus lofotensis, in which the lowest stem-joint is often provided with from five to nine slender cirri, but does not give attachment to a spreading root. The longest cup yet known in Rhizocrinus rawsoni was found in some individuals which were dredged by the “'Travailleur” in 1882, at a depth of 1900 metres (1000 fathoms), off Cape Blane, on the coast of Morocco, and were referred by Prof. Perrier to a new genus Democrinus.’ The cup is singularly elongated in form, as will be seen by comparing the measurements kindly furnished me by Prof. Perrier, with those given below for the Challenger, “ Blake,” and “ Porcupine ” specimens. Democrinus Parfaiti, Perrier= Rhizocrinus rawsoni, Pourtales. Dimensions. Length of the calyx from the terminal furrow to the first stem-joint, . 3 9:0 mm. Maximum diameter of the calyx, : . : - : 20055 Height of the radials, : 4 : - 2 : : 0-2 ,, Diameter of the stem-joints, . , ‘ : : : : LON Length of the stem-joints, . : : : 2:05.55 The basals of this type thus form a cup 9 mm. high from its lower extremity to the constriction at the level of the basiradial suture; while its maximum diameter is not more than 2 mm., twice that of the stem-joints. 1 Comptes rendus, t. xcvi., 1888, p. 450. REPORT ON THE CRINOIDEA. 265 The following table shows the great amount of variation in the proportions of the basal tube in other individuals of Rhizocrinus rawsoni, together with its diameter as compared with that of the stem-joints. How Species. obtained. Depth. Basal tube. Length of Stem. fathoms. f “Blake” 175 Challenger. 900 Rhizocrinus rawsoni. \| Capt. Cole, | “Investigator.” “Porcupine.” | 862 Rhizocrinus lofotensis, Sars. 300 Height. | Width. 55 2°50 5:0 2-00 3°5 3°00 3:0 1-75 2-0 1:50 mm. Stem-joints, Number. | Length. | Width. 68 53 45 30 67 3°50 2°25 300 2:00 3°50 2°25 2°25 1:25 1°50 0°50 N.B.—Pourtalés described his largest specimen of Rhizocrinus lofotensis as having a stem nearly 130 mm. long and composed of fifty-nine joints, the length of which averages three times their diameter. It will be seen from the above table that in absolute size, as well as in the proportions of the basals and of the stem-joints, the “ Porcupine” examples of this type are those which approach Rhizocrinus lofotensis most nearly ; though the stem is shghtly more robust than in Perrier’s specimens which have such an extraordinarily elongated calyx. Both are sinaller than those from the Azores, which are themselves smaller than the Caribbean specimens (though not always so in the length of the cup), a fact which is doubtless due to variations of temperature. The difference in size between the largest individuals of Rhizocrinus lofotensis found by Sars and Pourtalés respectively is likewise probably the result of the difference between the temperature of the Gulf Stream in the Florida Straits and that of the north-east Atlantic. The youngest specimens of Rhizocrinus rawsoni which I have seen are those dredged by the “Porcupine” in 1869 at a depth of 1207 fathoms off Cape Clear (Pl. LIIL. figs. 7, 8). Each has twenty-eight joints in the stem from the calyx to the root; but its length, which is only 20 mm. in the smaller, is 24-5 mm. in the larger individual. The uppermost joints are decidedly wider than those below them, the majority of which are elongated and cylindrical, only a few at the base of the stem (more in the larger than in the smaller individual) having the characteristic dicebox shape, with expanded ends (PI. LIU. fig. 7). The length of the calyx is almost the same in both specimens, 1°8 mm., though its diameter across the radials is greater in that which has the longer stem.~ It is mainly formed by the basals, which are 1:2 mm. in height. In the smaller individual (Pl. LIM. fig. 7) they expand very slowly upwards to the level of the lowest (Z00L. CHALL, EXP.—PART XXxl,—1884,) Ti 34 266 THE VOYAGE OF H.M.S. CHALLENGER. angle of the basiradial suture, where a radial rests on two basals; and then the surface of the radials slopes outwards rather more rapidly than that of the basal tube below it, so as to considerably increase the diameter of the cup. All the sutures, interradial, basiradial, and interbasal, are perfectly distinct; and there is a very faint circular constriction of the basal tube rather below its middle, analogous to that described by Sars in certain individuals of Rhizocrinus lofotensis.' This smaller individual has the lowest portions of the arms preserved, the longest of which has small pinnule-stumps on the fourteenth and sixteenth brachials, z.e., on the epizygals of the seventh and eighth syzygial pairs. In the larger individual, however, all the arms are broken away at the syzygy on the distal faces of the first brachials, which are a little higher and more trapezoidal in form than those of the smaller example (PI. LIII. fig. 8). The calyx is also slightly different in outline. The expansion of the basal tube from below upwards is a trifle more rapid than in the smaller form, so that its outline is less cylindrical ; while the radials are bent outwards a little at about one fourth of their height from their lower angles. This causes the calyx to appear slightly constricted at the highest level of the basiradial suture, a feature which is very marked in some varieties of the adult form. As compared with equal sized specimens of Rhizocrinus lofotensis, these young indi- viduals are distinguished by the relatively great height of the calyx, especially in the basal tube, and the expansion at the basiradial suture. The cup of Rhizocrinus lofotensis is not usually so high in proportion to its width; and it expands uniformly upwards, from the stem to the upper margin of the radials, so that its shape is pretty regularly obconical (Pl. IX. figs. 1,2; Pl. X. fig. 2). In Rhizocrinus rawsoni, however, the shape of the calyx varies in a most remarkable degree. It is elongated (exceeding 9 mm.) and relatively very narrow in Prof. Perrier’s specimens; while in those lately dredged by Captain Cole off Panama,’ the diameter varies between 80 and 90 per cent. of the length, which is not more than 4 mm. (wood- cut, fig. 19). But as a general rule, the form of the calyx may be described as elongated and subeylindrical. In a few individuals (woodcut, fig. 19, B) it expands uniformly from below upwards throughout its whole length, as is generally the case in Rhizocrinus lofotensis (Pl. X. fig. 2). Sometimes the width increases very slowly and sometimes more rapidly, but there is no indication of constriction at any point in the basals or radials. In other specimens the basals expand slowly but uniformly, and the radials slope outwards more strongly, as in Pl. LIIL. fig. 7. Sometimes again, the basals widen a little, but then narrow slightly till they join the radials, which slope outwards so as to again increase the diameter of the cup. : 1 Crinoides vivants, p. 5, Tab i. figs. 35, 39. 2 Tam indebted to Prof. F. J. Bell, F.Z.S., for calling my attention to those four remarkable specimens which are divided between the Zoological and Geological Departments at the Museum of Natural History. The keepers of these departments, Dr. A. Giinther, F.R.S., and Dr. H. Woodward, F.R.S., kindly permitted me to examine them, and the former gentleman was good enough to allow the accompanying figures to be made of the two abnormal individuals under his charge. REPORT ON THE CRINOIDEA. 267 In a considerable number of individuals from different localities on both sides of the Atlantic, I have found the radials to be marked by a circular furrow of variable depth. It crosses the body of the radial at the level of the upper angles of the basals between which the radial rests, as is well shown in the young specimen represented on Pl. LIIL fig. 8. binis = ia In the more mature individual from the Caribbean Sea, shown in PI. IX. fig. 3, the furrow crosses the radials at about half their height; while in one of the specimens from the neighbourhood of the Azores (Station 76) the basals are much less angular at the top, so that the radials are more nearly oblong and almost entirely above a rather strong constriction at the level of the basiradial suture (Pl. X. fig. 3). Other individuals, however, are entirely desti- tute of any indication of such a constriction. bi z : Fic. 19.—The calyx and arm-bases of two specimens of This is the case, for example, with those ence rawsoni from Panama-; x 4, In both cases i é the cup is unusually wide in proportion to its height ; dredged by Captain Cole off Panama, which and in the right hand specimen (B) the grouping of the lower brachials is very irregular, are further remarkable, not only for the great relative width of the basal cup as shown in the woodeut (fig. 19), but also for the extreme variation in the position of the first pinnule. In one individual this is on the epizygal of the seventh brachial in two arms, on that of the fifth in two others, and on that of the fourth in the remaining one. In four arms of another specimen the epizygals bearing the first pinnule are respectively those of the third, fourth, fourth, and fifth brachials ; while in a third individual three arms are normal, with a pinnule on the third epizygal, the two others not bearing a pinnule till the next (fourth) joint. Lastly, in a fourth individual every one of the arms is developed abnormally. Three of them are shown in woodcut, fig. 19,B. I will not attempt to offer an opinion upon the grouping of the syzygies and muscular articulations in this specimen. But in one arm at least there appear to be two syzygies in succession ; so that the composite brachial is in three parts instead of in two only. This is a variation of some interest, as it is normal in the arms of Hyocrinus (Pl. VI. fig. 1). Both types of brachial, that with one and that with two syzygies, occur in different species of the Paleozoic Heterocrinus, as pointed out already (ante, p. 58). Although the occurrence of Rhizocrinus rawsoni in the East Atlantic and its more striking peculiarities, especially the length of the basals, were noticed in the first Report upon the Caribbean Crinoids’ which Prof. Perrier quotes, he was led to describe the 1 Bull. Mus. Comp. Zodl., vol. x., No. 4, p. 174. 268 THE VOYAGE OF H.M.S. CHALLENGER. “Travailleur ” examples of this species as a new generic type Democrinus,' which is really, however, only a synonym of Rhizocrinus. His account of Democrinus was as follows :— Le Democrinus se distingue immédiatement de tous les autres genres par la composition de son calice formé de cing longues basales constituant 4 elles seules un calice en entonnoir; un sillon circulaire sépare ces cinq basales de cinq radiales rudi- mentaires, en forme de croissant, alternant avec elles et surmontées elles-mémes de cing radiales axillaires libres, rectangulaires, mobiles, sur lesquels se fixent respectivement cing bras, beaucoup moins larges que les radiales. Ces bras se brisent trés facilement au niveau de leur articulation avec les radiales axillaires qui se rabattent alors sur la votite du calice.” He further adds that in Rhizocrinus “les basales sont confondues et le calice formé en partie de radiales.” The basals of Rhizocrinus, however, are very far from being “confondues,” but are large and independent, as was pointed out by Pourtalés in 1868 and 1874, and by myself in 1877 and 1882. But Perrier, unaware of this fact, was unfortunately misled by the erroneous descriptions of the basals as internal and concealed which were given by Sars and Ludwig (ante, pp. 249-251); so that when he found a Rhizocrinus-like form with long and well defined basals, he naturally (though erroneously) considered it as new to science. Although, however, the radials of Democrinus may be small and rudimentary externally, there is no reason why the calyx should consequently be considered as formed by the basals alone; though Perrier regards this as another character distinguishing Democrinus from Rhizocrinus. In one of the specimens of Rhizocrinus lofotensis which was figured by Sars’ the radials are quite small externally; but they have large distal faces for the attachment of muscles and ligaments, the inner surfaces of which form the funnel lodging the lower part of the ccelom. The same is undoubtedly the case with the radials of Democrinus, to which the movable first brachials (axillaries, Perrier) are attached just as in Rhizocrinus. It is difficult to understand why the radials of this type should be considered as forming part of the calyx, while those of Democrinus are excluded from it on account of their smaller size. On the same principle one would have to describe the cup of those species of Antedon in which the first radials do not appear externally, as formed by the centro-dorsal only ! Prof. Perrier describes the rudimentary radials of Democrinus as separated by a circular furrow from the basals below them. Buta drawing of the type which he has kindly sent me, shows that while the basiradial suture is marked by five strong elevations with intervening depressions in which the radials rest, the furrow crosses the radials at the level of the highest angles of the basals. This furrow is more or less distinct in various specimens of Rhizocrinus rawsoni (Pl. IX. fig. 3; Pl. LIT. fig. 8), as has been pointed out already. But it can hardly be said to “separate” the radials from Comptes rendus, t. xevi. p. 450. 2 Crinoides vivants, Tab. ii. fig. 44. REPORT ON THE CRINOIDEA, 269 the basals, as it crosses the former at a variable distance from their lower angles. Ina few cases, however, the basiradial suture is more uniformly horizontal, and not marked by alternate elevations and depressions (Pl. X. fig. 3); so that the furrow really does indicate the line of separation between the basals and radials. But this is far from being the case in Prof. Perrier’s drawing of the Democrinus calyx. The fragmentary condition or absence of the arms in his specimens is nothing unusual. Only one-third of all the individuals of Rhizocrinus rawsoni which T have examined have any arms at all, including the young form represented in Pl. LIII. fig. 7. There may, however, be as many as one hundred and twenty joints, or rather sixty syzygial pairs, with pinnules on all but the first three or four. But they are very apt to break away at the syzygy in the first brachial, which Perrier speaks of as an articulation between a radial axillary and the lowest arm-joint. This had happened in two of his three speci- mens of Democrinus, which are “ totalement dépourvus de bras; le troisieme n’en présente que des restes trés courts, d’aprés Jesquels il est aisé de voir que les bras devaient étre extremement peu développés.” The drawing of this individual which he has sent me shows that its longest arm-fragment consists of only five joints, z.e., two composite brachials and the hypozygal of a third. This fully accounts for the absence of pinnules, which never appear below the third epizygal in any Rhizocrinus ; and I have little doubt that further research will prove the existence of properly developed, pinnule-bearing arms in the so-called Democrinus. But I do not suppose that they are quite as fully developed as those of the Caribbean variety of Rhizocrinus rawsont. This has a stem more than twice the width of that of Democrinus; and it is generally more robust, though the ealyx is distinctly shorter and broader than in Perrier’s type. The “Travailleur” specimens are of interest, both on account of their aberrant form, and because they give another locality for Rhizocrinus rawsoni in the East Atlantic in addition to the two discovered by the “ Porcupine” in 1869; while the “Talisman” met with another locality of the type during the dredgings of 1883." It is remarkable for its close resemblance to the Rhizocrinus londinensis from the London Clay, isolated stem-joints of which were referred by Forbes” to Bourgueticrinus. But a well preserved and very characteristic calyx has since been discovered, and is now to be seen in the Natural History Museum at South Kensington. 1 Democrinus dies hard. Perrier’s mistake about the condition of the basals in Rhizocrinus was pointed out in the Ann. and Mag. Nat. Hist., ser. 5, vol. xi., 1883, p. 334. Under these circumstances the character on which he relied as distinguishing Democrinus from Rhizocrinus became non-existent; and I therefore expressed my conviction that Democrinus Parfaiti and Rhizocrinus rawsoni were identical. Perrier, however, appears to be of a different opinion, for in the Preliminary Report of Mons. A. Milne-Edwards, the President of the “ Talisman” Commission of 1883, Democrinus is specially mentioned as one of the captures (Comptes rendus, t. xevii. p. 1392) ; while in the semi-official account of the collection published in La Nature (No. 572, p. 391) by Mons. H. Filhol, also a member of the Commission, particular reference is made to Democrinus Parfaiti. As the addition of a new generic type to the family Bourgueticrinide is of considerable importance in many ways, Prof. Perrier’s revised account of its characters will be awaited with interest, both by zoologists and by palzontologists. 2 British Tertiary Echinoderms, p. 36. 270 THE VOYAGE OF H.M.S. CHALLENGER. Family Pentacrinip&, d’Orbigny, 1852. Calyx small relatively to the stem and arms, composed of five basals and five radials, with under-basals in one genus. The rays divide from one to eight or ten times. The stem bears verticils of cirri at intervals. Two joints are united by syzygy at each node, to the upper one of which the cirri are articulated. The internodes are traversed by five ligamentous bundles which are interradially disposed and give rise to a more or less petaloid figure on the joint-faces. No root nor radicular cirri. Remarks.—Although definitions of this family have already been given by d’Orbigny, de Loriol, and Zittel, they have been based almost entirely upon palzeontological knowledge, and have not therefore given sufficient prominence to the syzygies between certain of the stem-joints, and to the ligamentous structures which produce the well known petaloid markings on their faces. The regular verticillate arrangement of the cirri along the whole length of the stem is especially characteristic of the Pentacrinide among the Neocrinoids, though there are a few Palzocrinoids, eg., Belemnocrinus florifer, in which this peculiarity presents itself. But it does not necessarily follow that the nodal joints in the stems of these older forms are the epizygals of syzygies, as is the case in the Pentacrinide. The same may be said of the so-called Encrinus beyrichi, in which Picard has described a verticillate arrangement of the cirri on the stem, without mentioning the presence of any syzygies at the nodes.? In Apiocrinus and Bourgueticrinus the upper part or even the whole of the stem is entirely free from cirri; and even when they do occur in verticils, it is only by two at a time instead of by fives, as in all the recent Pentacrinide except the one species Penta- crinus alternicirrus (Pl. XXV.; Pl. XXVIL. figs. 1-3). Further, there is nothing like a syzygy between the two joints forming a node in a Bourgueticrinus-stem, which are articulated to one another in the usual way. It is in fact the characters of the stem, much more than those of the calyx, which constitute the special distinctive mark of the Pentacrinide. For although Hxtracrinus is known by its under-basals, the composition of the calyx is identical in Millericrinus and Pentacrinus, and also in Metacrinus, if we follow strict morphology and consider the second radials as really arm-joints. The calyx of Balanocrinus is unfortunately not yet known. The genus was founded by Agassiz for a fragment in the Basle Museum, which he supposed to be a peculiar form of calyx. But de Loriol’ has shown that “ce prétendu calice n’est qu'un fragment de tige attaqué et deformé par un parasite.” Agassiz had, however, referred the stems associated with it to Pentacrinus subteres; and de Loriol, finding that the stem-joints of 1 Ueber eine neue Crinoiden-Art aus dem Muschelkalk der Hainleite bei Sondershausen, Zeitschr. d. deutsch. geol. Gesellsch., Jahrg. 1883, p. 201. 2 Swiss Crinoids, p. 163. REPORT ON THE CRINOIDEA, Paykel this type really are different from those of other Pentacrinide, has re-established the genus Balanocrinus wpon them. The five sectors of each more or less circular face have no ridges or denticulations along their sides, those being limited to the outer margin of the joint-face. They are usually therefore of greater size than the corresponding parts on the stem-joints of Hxtracrinus and Pentacrinus, which are sometimes much constricted by the development of ridges at their sides. The stem-joints of Balanocrinus, therefore, are somewhat like those of Millericrinus; though in the latter type the whole joint- face is uniform in character, and not marked out into sectors as is the case in the Penta- erinide. Many Paleocrinoids have jomts somewhat like those of Balanocrinus, ‘.e., crenulated round the edge, but nothing more. The genus commenced with Pentacrinus in the Trias, and survived to the Lower Neocomian, no remains of it having yet been found at any higher horizon ; while I have not met with this simple form of stem-joint in any recent species. Owing to the deficiency of our knowledge respecting the nature of the calyx of Balanocrinus, I have found it necessary to use the characters of the stem as the basis of the classification of the family. Balanocrinus may have under-basals like Haxtracrinus, or more than three radials like Metacrinus; but until we know more about its calyx a classification of the Pentacrinide must depend primarily upon the varying features of the stem. I. Five to eight large teeth at the sides of each petaloid sector, most of which start from the outer edge of the joint-face, while the remainder meet their fellows in the interpalmar spaces. 1. Three radials, . : : : : : c : . Pentacrinus, 2. More than three radials, . : : . Metacrinus. IL. Sectors linear with delicately crenulated ages! Under- basals. The first eter much prolonged downwards. Secondary arm-trunks each bear a succession of armlets on the same side, Lzxtracrinus. III. Joint-faces crenulated round the edge only, not along the sides of the sectors, . Balanocrinus. Three other supposed genera have also been referred to this family. One is [socrinus, von Meyer,’ of which the stem is scarcely known ; while it is probable that von Meyer’s description of the primary rays as consisting of but two joints, basals being likewise wanting, is also somewhat incorrect. The mode of division of the rays, on which von Meyer laid considerable stress, is perfectly normal. I prefer therefore to refer the type, temporarily at any rate, to the genus Pentacrinus, as has been done by Bronn and others, though I will not attempt to follow them into specific details. Another unrecognised genus of the Pentacrinide is the Chladocrinus of L. Agassiz.’ After defining the stem of Pentacrinus as “ portant de distance en distance des rayons simples verticillés,” he continued, “on pourra désigner sous le nom de Chladocrinus les especes dont les rayons accessoires forment des verticillés plus ou moins distans.” 1 Tsocrinus und Chelocrinus, Museum Senckenbergianum, Frankfurt, 1837, p. 251. * Prodrome d’une Monographie des Radiaires ou Echinodermes, Mém. de la Soc. des Sci. Nat. de Neuchatel, t. i., 1835, p. 194. 272 THE VOYAGE OF H.M.S. CHALLENGER. No further definition of Chladocrinus was ever given by Prof. L. Agassiz; and it is not surprising therefore that the genus has never been accepted by naturalists. The remaining type which is supposed to be generically distinct from Pentacrinus, is the Cainocrinus of Forbes.’ It has recently been revived by de Loriol;’ but since it was based on a misconception, and its only distinctive character depends upon a feature which is very variable among the recent species, viz., the presence or absence of a closed ring of basals, I see no good in retaining it (see pp. 281-283). Practically, therefore, owing to the well marked characters of Hxtracrinus and our want of knowledge of Balanocrinus, a definition of Pentacrinus for the study of recent forms need only emphasise those points in which it differs from Metacrinus. I have, however, referred to one or two characters in which the genus differs from Hatracrinus. Genus Pentacrinus, Miller, 1821.’ 1761. Palmier marin, Guettard, Mémoires de Mathématique et de Physique tirés des Registres de ]’Academie Royale des Sciences, de ’année MDCCLYV., Paris, 1761, p. 225. 1762. Encrinus, Ellis, Phil. Trans., vol. lii. pt. i. for the year 1761, London, 1762, p. 358. 1766. Isis, Linneus, Systema Nature, ed. xii., Holmie, 1766, t. i. p. 1288. 1816, Enerinus, Lamarck, Histoire Naturelle des Animaux sans Vertébres, t. ii., Paris, 1816, p. 432. 1820. Pentacrinites, von Schlotheim, Die Petrefactenkunde, Gotha, 1820, p. 327. 1821. Pentacrinus, Miller, A Natural History of the Crinoidea, Bristol, 1821, p. 45. 1832. Pentacrinites, Goldfuss, Petrefacta Germaniae, Dusseldorf, 1832, t. i. p. 168. 1832. Solanocrinites, Goldfuss, Ibid., p. 168. 1834. Pentacrinus, de Blainville, Manuel d’Actinologie, Paris, 1834, p. 257. 1834. Encrinus, de Blainville, [bid., p. 254. 1835. Pentacrinus, Agassiz, Mém. de la Soc. d. Sci. Nat. de Neuchatel, t. i. p. 194. 1835. Chladocrinus, Agassiz, [bid., p. 195. 1836. Pentacrinus, Buckland, Geology and Mineralogy, London, 1836, vol. i. p. 432. 1837. Isocrinus, von Meyer, Museum Senckenbergianum, Frankfurt, ii. p. 251. 1843. Pentacrinus, Miiller, Abhandl. d. k. Akad. d. Wiss. Berlin, Jahrg. 1841, p. 177. 1845. Pentacrinus, Austin, A Monograph on Recent and Fossil Crinoidea, Bristol, 1843-45, p. 110. 1845. Pentacrinus, Desor, Bull. Soc. d. Sci. Nat. de Neuchatel, vol. 1. pp. 213, 214. 1845. Isocrinus, Desor (non von Meyer), Ibid., p. 213. 1845. Balanocrinus, Agassiz (non de Loriol), in Desor, Jbzd., p. 214. 1847. Pentacrinus, VOrbigny, Cours élemént. de Paléontol. et de Géol. stratigr., t. ii, Fasc. 1, Paris, 1852, p. 149. 1852. Tsocrinus, d’Orbigny, Ibid., p. 149. 1 British Tertiary Echinoderms, p. 33. 2 Swiss Crinoids, pp. 111, 112. 3 The above list contains, I believe, all the most important references to the recent Pentacrinus since the time of Guettard, together with notices of the chief paleontological works in which this type and its fossil representatives are mentioned. But it makes no pretence whatever of recording all the various names which have been bestowed at different times upon fragments of fossil Pentacrinid. A task of this kind is scarcely worth undertaking, as the result would be totally incommensurate with the labour involved. REPORT ON THE CRINOIDEA. 273 1852. Pentacrinus, Forbes, Monograph of the Echinodermata of the British Tertiaries, p. 33. 1852. Cainocrinus, Forbes, I[bid., p. 34. 1857. Pentacrinus, Pictet, Traité de Paléontologie, 2™° éd., Paris, 1857, t. iv. p. 342. 1857. Isocrinus, Pictet, Ibid., p. 344. 1857. Comatula (pars), Pictet, Ibid., p. 288. 1862. Pentacrinus, Dujardin and Hupé, Hist. Nat. des Zoophytes, Echinodermes, Paris, 1862, p. 179. 1864. Cenocrinus, Wyv. Thoms., The Intellectual Observer, August 1864, p. 3. 1864. Neoerinus, Wyv. Thoms., Lbid., p. 7. 1864. Pentacrinus, Liitken, Videnskabelige Meddelelser fra den naturhistoriske Forening i Kjébenhavn, 1864, Nr. 13-16, p. 207. 1872. Pentacrinus, Wyv. Thoms., Proc. Roy. Soc. Edin., vol. vii. p. 765; and The Depths of the Sea, p. 435. 1875. Picteticrinus, de Loriol, Monographie Paléontologique et Géologique des Etages Supérieurs de la forma- tion Jurassique des Environs de Boulogne-sur-Mer, 2™° partie, p. 297. 1876. Pentacrinus, Quenstedt, Petrefactenkunde Deutschlands, Bd. iv.; Asteriden und Encriniden, p. 186. 1879. Pentacrinus, de Loriol, Monographie des Crinoides fossiles de la Suisse, p. 114. 1879. Cainocrinus, de Loriol, Lbid., p. 111. 1879: Pentacrinus, Zittel, Handbuch der Paleontologie, Paleozoologie, Miinchen und Leipzig, 1876-1880, Bd. i. p. 393. 1880. Pentacrinus, P. H. Carpenter, Journ. Linn. Soc. Lond. (Zool.), vol xv, p. 210. 1882. Pentacrinus, P. H. Carpenter, Bull. Mus. Comp. Zoél., vol. x. p. 167. 1884. Pentacrinus, P. H. Carpenter, Proc, Roy. Soc. Edin., vol. xii. p. 359. A. Characters of the Genus. The petaloid sectors on the faces of the stem-joints are bordered by a few large ridges, of which the smaller proximal ones meet those of adjacent sectors in the inter- petaloid spaces, while the large distal ridges reach the outer edge of the joint. The supranodal joints are scarcely modified for the cirrus-sockets, and the articular facets rarely reach the upper edges of the nodal joints." The cirri consist of from twenty to fifty joints, and vary considerably both in length and in appearance. The basals may be very small knobs, or form a complete ring, and have but a slight tendency to downward extensions of their lower angles. There are never more than three radials, none of which bear pinnules. The rays may divide five times, but rarely more than thrice; and their Bundesrat are equal in value or nearly so. The basal joints of the lower pinnules are usually rather broad and flattened laterally, with sharp dorsal edges. Remarks.—The genus Pentacrinus is generally, and with good reason, attributed to Miller. But a few authors have associated with it the name of von Schlotheim,.’ It is true that this able paleontologist used Pentacrinites as a generic name a year before the publication of Miller’s classical monograph ; but he made no attempt to define it as Miller did, nor did he give diagnoses of any of the species which he referred to the genus.. In 1 Tn several fossil species, however, the cirrus-facets take up the whole height of the nodal joints. 2 Die Petrefactenkunde, Gotha, 1820, p. 327. (ZOOL, CHALL, EXP,—PART Xxxu.—1884.) i 35 274 THE VOYAGE OF H.M.S. CHALLENGER. fact, the first of these, Pentacrinites vulgaris, designates a fossil type to which he also referred (under the name of Encrinus caput-Meduse) the recent specimens described by Guettard and Ellis. These were subsequently referred by Miller to his Pentacrinus caput-Meduse (= Pentacrinus asterius, Linn, sp.) ; and the type was eventually rendered classical by the researches of Miiller. Under these circumstances I see no reason for departing from the practice of d’Orbigny, Forbes, Pictet, de Loriol, and Zittel, and have therefore attributed the genus to Miller, with the date 1821. When establishing it, he simply converted into a generic designation the name which had long been commonly employed for fragments of stems with the characteristic petaloid markings on their terminal faces. Miller’s generic diagnosis of this type, like those of the numerous other Crinoids described by him, corresponds to the definition of a family, when considered by the help of our present knowledge. Five species were established by Miller'—(1) the recent Pentacrinus caput-Meduse from the West Indies; (2) the two fossil species from the Lias, Pentacrinus briareus and Pentacrinus subangularis; and (3) two other fossils which need not be considered here. Although apparently taking the single recent species then known as the type of the genus, he gave a generic diagnosis which represents, although imperfectly, the dissected calyx of one of the two Liassic species. These have the radials prolonged downwards over the upper stem-joints between and below the outer ends of the basals ; and the Messrs. Austin consequently proposed to establish the new genus Hxtracrinus for their reception, while restricting Pentacrinus to species having the general character of the recent Pentacrinus caput-Meduse (= Pentacrinus asterius, Linn, sp.). Miller described the “ pelvis” of the fossil Pentacrinus briareus and Pentacrinus subangularis as similar in character to that of the recent Pentacrinus asterius, namely, as consisting of five small and nearly cuneiform basals in contact by their central ends. The Messrs. Austin, in accordance with their peculiar method of nomenclature, gave the name “dorsocentral plate” to the pelvis of Miller (basals, Miiller) ; and they described that of Pentacrinus asterius as “resembling an enlarged and thickened supracolumnar joint,” without divisions, the salient angles of which alternate with the five first radials, or, as they called them, the first series of perisomic pieces. The pelvis of the three fossil species Pentacrinus johnson, Pentacrinus tuberculatus, and Pentacrinus milleri, was described as closely resembling that of Pentacrinus asterius; but in their diagnoses of Extracrinus briareus and Extracrinus subangularis they differed considerably from Miller and Goldfuss. They gave the name dorsocentral plate, not as usual to the pelvis of Miller as in Pentacrinus asterius, but to five small and nearly concealed pieces which are placed beneath the true pelvis, and were unknown to Miller. They are radial in position, and not interradial like the pieces described by Miller and Goldfuss as composing the pelvis of these two Liassic species. These, the true basals, which thus alternate with 1 A Monograph on Recent and Fossil Crinoidea, Bristol, 1843-45, p. 95. REPORT ON THE CRINOIDEA. 275 the elements of the so-called dorsocentral plate, were described by the Messrs. Austin as “solid pointed pieces, whose points pass outward, and rest on the salient angle of the pentagonal column,” precisely, in fact, like the rays of the stellate dorsocentral plate or pelvis of Pentacrinus asterius, with which Miller had rightly regarded them as homologous. The Messrs. Austin, however, supposed Miller to have been in error upon this point, as they believed the so-called dorsocentral plate of Hxtracrinus to be homologous with that of Pentacrinus, not paying any attention whatever to its position with regard to the radial symmetry of the animal. Neither did they notice that in Pentacrinus the five elements composing the dorsocentral plate are perforated by bifur- cating canals, which occur in Hxtracrinus, not in the component pieces of the dorso- central plate, but in those of the next series, the pelvis of Miller; and they were conse- quently led to regard these last, the basals of Miller, as representing the first series of perisomic plates (or the first radials, Miiller) of Pentacrinus; while the first radials of Extracrinus, alternating in position. with the basals, were described by them as a second series of lateral or perisomic pieces which are unrepresented in Pentacrinus. The fact is, however, that it is the dorsocentral plate of the former genus which is not represented in Pentacrinus, the pelvis of which represents the so-called first series of perisomic plates in Extracrinus, as was rightly supposed by Miller. The two sets of plates are precisely similar in their position relatively to the radial symmetry of the animal and in being perforated in the same way by bifurcating canals. These two important points, which were entirely left out of consideration by the Messrs. Austin, demonstrate the a of the first series of perisomic plates in Hatracrinus, not only with the pelvis or dors central plate of Pentacrinus, but also with the outer circlet of basals in Hnerinus ; while the five small, nearly concealed pieces forming the so-called dorsocentral plate of Eextracrinus, which alternate with the true or outer basals, obviously represent the inner circlet of basals of Encrinus. The Messrs. Austin were fortunate enough to obtain a specimen of Extracrinus briareus showing the interior of the calyx, the centre of the floor of which is occupied by the five small, radially placed elements of the so-called dorsocentral plate; and the resemblance in every respect between these and the inner circlet of basals in Hnerinus is so close as to leave little doubt that they are homologous with one another. It is therefore somewhat striking to find that the extensive downward prolongation of the: first radials over the upper stem-joints, which is the chief characteristic of Extracrinus, as defined by the Messrs. Austin, is also found, though to a smaller extent, in. Encrinus, as pointed out by Beyrich. Hncrinus, like Kxtracrinus, has a dicyclic base; but the same tendency to downward prolongation of the radials is seen in Pentacrinus naresianus (Pl. XXX. fig. 1) and more distinctly in Metacrinus (Pl. XXXIX. fig. 1; Pl. XLIX. fig. 2). The Austins’ genus Hztracrinus has not met. with the attention which it deserved, 276 THE VOYAGE OF H.M.S. CHALLENGER. possibly on account of the clumsy nomenclature adopted by these authors. Ramsay, Phillips, and Etheridge have used it in this country; but the well known German paleontologist Quenstedt," who has probably seen it in greater abundance than any other naturalist, speaks of it in a decidedly scoffing tone. This, however, is only to be expected from one who does not separate Bowrgueticrinus from Apiocrinus. Zittel mentions Austin’s name, but without committing himself to an acceptance of it; and I have reason to believe that M. de Loriol is prepared to accept the genus after it has been redefined in a manner which is consistent with the present state of our knowledge. The genus Hxtracrinus, which includes the two groups “ Briariden” and “ Subangu- laren” of Quenstedt, is thus distinguished by the presence of under-basals (dorsocentral plate, Austin) and the downward prolongation and jointing of the radials. But it also differs very markedly from the Post-Liassic and recent Pentacrinites in the characters of its stem and arm-divisions. The precise structure of the stem of Extracrinus, i.e., the relations of its nodal and internodal joints, has yet to be worked out. Some fragments of stem, probably from near the top, seem to consist entirely of nodal joints; while in others there are several joints between any two whorls of cirri, just as in the ordinary Pentacrinites. The joint- faces of Eaxtracrinus, however, are very different from those of Pentacrinus. In the latter genus, the five petaloid figures indicating the position of the stem ligaments are more or less oval in shape, pointed at one or both ends, and bounded by strong ridge- like processes, with alternating furrows (Pl. XIII figs. 2-6, 9-11; Pl. XXII. figs. 18, 14, 22; Pl XXX. figs, 25-30; Pl XXXa. fig. 7; Pl. XXXII. fig. 3; Pl. XXXVII. fig.22). There may be only about three of these on each side of the petal, as in most recent forms, or there may be from six to twelve of a smaller size. But all of these ridges, except those most centrally placed, slant inwards from the edge of the joint, where their outer ends cause the denticulation which is so marked in all but the oldest specimens (Pl. XIX. figs. 2-5; Pl XXVII. fig. 1; PL XXXa. fig. 6; Pl. XXXI. fig. 3; Pls. XXXV., XXXVL). In Extracrinus, however, the five interradial petals are quite narrow, and much less distinctly oval than in Pentacrinus, sometimes being linear with rounded outer ends. Even when the joints are stellate the petals do not occupy more than the central portion of each ray of the star, stead of the whole of it as in Pentacrinus; and when the joints are pentagonal or circular there is a more or less triangular space between every two petals, which is plain and devoid of sculpture. Then again the markings at the sides of the petals are much more delicate than in Pentacrinus, having more the character of strize or crenulation than of coarse ridges. They are also much more numerous than in Pentacrinus, and are strictly limited to the sides of the petals, not reaching the outer edge of the jomt. These characters are well shown in several of the figures published 1 Encriniden, p. 270. re re REPORT ON THE CRINOIDEA. 277 by different paleontologists, e.g., on pl. 53 of Buckland’s Geology and Mineralogy, figs. 9-13; on Tab. 101 of Quenstedt’s Encriniden, especially figs. 24, 27, 33, and 37; and also on pl. 12 of the Messrs. Austin’s Monograph, figs, d,f, k,n, 0, 7. None of these authors, however, seem to have noticed the distinction of this type of joint from that of the ordinary Pentacrinide, either recent or fossil ; and attention was first drawn to it by de Loriol, as will be pointed out subsequently. In the ordinary Pentacrinide, as in the multiradiate Comatule, there is no special regularity in the mode of division of the secondary and tertiary arms. The twenty secondary arms borne upon the distichal axillaries may either remain simple, or fork again, once or oftener. But in most cases the forking is very irregular. Secondary (palmar) axillaries may appear upon any of the four secondary arms; and the two tertiary arms borne by them are of equal size, and have equal power of forking again, though as a rule they do not all do so. A good instance of this is shown in Miller’s figure 1 of Pentacrinus asterius (caput-Meduse), which is represented more diagrammati- cally in Quenstedt’s Tab. 97, fig. 3. A similar arrangement has been described by Liitken in Pentacrinus miilleri2 while it also occurs in Pentacrinus maclearanus, Pentacrinus wyville-thomsoni, and Pentacrinus alternicirrus (Pl. XIV.; Pl. XV. fig. 1; Pl, XIX. fig. 2; Pl. XXV.; Pl. XXVI. fig. 4). In all these cases the secondary (and tertiary) axillaries are limited to the outer arms of each successive pair, so that the arrange- ment of the arms on the ray is 2,1; 1, 2; or 2, 1,1; 1,1, 2.? But the two (or four) inner arms are equivalent to the outer ones in all respects, neither of them dividing again. While the arm-division in Hatracrinus proceeds to a much greater extent than in Pentacrinus, it is confined as a rule to the sides of the ray, only the outer arm of each successive pair bearing axillaries, just as in the secondary and tertiary arms of Pentacrinus asterius, Pentacrinus miilleri, &e. The four tertiary arms which spring from each pair of palmar axillaries are rarely of equal size, and never absolutely equi- valent. The two inner ones are usually rather the smaller, and except in some forms of Extracrinus subangularis do not divide again. Each of the larger outer arms, however, divides again after a few joints, but the division is unequal. The smaller inner face of the axillary, 7.e., that turned towards the other axillary, bears a slender armlet; while the main arm-trunk is continued directly onwards without change of direction. It gradually diminishes in size, and gives off at short intervals a series of slender armlets from its inner side, but it never really forks. But for the pinnules borne by it and its subordinate armlets, one would be almost inclined to say that the distichal axillary bears two secondary arms which have long slender pinnules placed at intervals upon their adjacent inner faces, but none whatever upon their outer sides. These organs are real 1 Op. cit., p. 48, pl. i. 2 Om Vestindiens Pentacriner, loc. cit., pp. 2038, 204. 3 The Caribbean Antedon spinifera often shows exactly the reverse condition to this. Palmar axillaries are frequently only developed on the inner pair of the four secondary arms, so that the grouping on each ray is 1, 2; 2, 1. 278 THE VOYAGE OF H.M.S. CHALLENGER. arms, however, for they bear the pinnules as their larger fellows do; and in some forms the lowest of them (tertiary arms) have a series of unequal axillaries and bear armlets on their inner faces just as the large outer arms do. In such individuals these ner tertiary arms are more equal in size to the outer pair. The two extreme types are well represented on Tab. 97 of the Encriniden, figs. 5 and 6, by Quenstedt, who partially founds upon them the distinction between the “ Briariden” and the ‘“‘Subangularen.” In the former group the inner tertiary arms are undivided armlets like those which come off farther out on the ray; while the inner tertiary arms of the Subangularen, though smaller than the outer ones, bear armlets on their inner faces, which correspond to those on the inner faces of the outer arms that spring from the same axillaries. Owing to the presence of these armlets on the inner tertiary arms, the Subangularen generally have the “ finger-reichsten Krone” as pointed out by Quenstedt. This is not always the case, however, for in a specimen from the Posidonia-beds of Holzmaden, which is figured by him,’ the inner tertiary arms are undivided, and their successors are more equal to the outer arms of the ray than in some forms of Extracrinus briareus. Under the name of Pentacrinus briareus minutus, Quenstedt? has figured a curious little species in which the division of the arms seems to be somewhat irregular, and the distinction of arms and armlets less marked than is usually apparent in Hetracrinus. But I do not think that this variation, even if it be established, need have much effect upon the stability of Kxtracrinus as a generic type. The differences between the Liassic and the recent Pentacrinide on which the genus was founded by the Messrs. Austin were at first regarded by the late Sir Wyville Thomson as of merely subgeneric value. Believing that Pentacrinus briareus “seems to have a just claim to be recognised as the type of the genus Pentacrinus,” he introduced the name Cenocrinus for the Pentacrinus caput-Meduse of Miiller, and one or two fossils which closely resemble it.? He subsequently abandoned this name, however, and referred the type to Pentacrinus as all later writers have done, some recognising Hatracrinus as a separate genus and some not. The Messrs. Austin* pointed out that Miller “in his arrangement of the Crinoidea has taken the Pentacrinus caput-Meduse for the typical species, while at the same time his generic plate represents the dissected skeleton of quite a different Crinoid. In the hope to remedy this intermingling of genera, we propose to retain Miller’s genus Pentacrinus, and to continue the Pentacrinus caput-Meduse as the type of the genus;” while the name Hxtracrinus was proposed for the Liassie Pentacrinus briareus and Pentacrinus subangularis. This arrangement seems decidedly preferable to that proposed by Sir Wyville, who eventually gave up Cenocrinus as a subgenus ; though I cannot learn that he ever formally adopted Hxtracrinus. A second subgenus of Pentacrinus besides Cenocrinus was also proposed by Sir 1 Eneriniden, Tab. 101, fig. 1. 2 Thid., Tab. 99, fig. 177. 3 Sea Lilies, The Intellectual Observer, August 1864, p. 3. * Monograph, p. REPORT ON THE CRINOIDEA. 279 Wyville in 1864,! the type being a new West Indian species which he designated as Pentacrinus (Neocrinus) decorus. The differences between this type and Pentacrinus asterius (caput-Meduse) are undoubtedly considerable, as I have expressed by separating the two as far as possible in my arrangement of the species (see p. 299). But they are rather physiological than morphological in character, and one or two errors of observation have caused them to appear greater than they really are. There are syzygies below the nodal joints of Pentacrinus asterius (Pl. XII. figs. 3, 5, 8), just as in Pentacrinus decorus (Pl. XXXVI; Pl. XXXVII. figs. 5-8, 12, 19, 21); so that although the stem of the former species is very strong and rigid, it can hardly be said to be distinguished by the “absence of all provision for its rupture,” such as Sir Wyville* described in the more slender stem of Pentacrinus decorus. The supposed difference between the disks of Pentacrinus asterius and Pentacrinus decorus, which was founded on a belief in the presence of tooth-like oral plates in the former genus, is also due to error, owing to the unsatisfactory condition of Michelin's specimen, which was said to possess these embryonic structures. Sir Wyville recognised this subsequently when he obtained a spirit specimen of Pentacrinus asterius, the disk of which he described as follows : *—‘ The perisome of the disk is covered with irregular calcareous plates, and at the free inner angles of the interradial spaces these plates become closer, and form a solid kind of boss; but there are no distinct oral plates.” On the other hand, the disk of Pentacrinus decorus* (Pl. XXXIV. fig. 2) could hardly be called “comparatively unprotected” as distinguished from that of Pentacrinus asterius, which Sir Wyville described on the previous page as “uniformly defended and plated with calcareous pavement.” In the nature of the arms, however, there is a considerable difference between the two types, as was well described by Sir Wyville. Those of Pentacrinus asterius are “ greatly multiplied, large and strong. No syzygies, save those at the base, which can be used on an emergency, tend to diminish their strength, an arrangement essential to the full supply of food in their fixed condition.” On the other hand, in Pentacrinus decorus the number of arms is “greatly less, and the arms are provided throughout with syzygies, an arrangement apparently suitable to its greater liability to trivial accidents in its free condition.” He went on to say, “ At first I had some doubt as to the propriety of making this species the type of a new subgenus, and any one of the above characters would certainly not have afforded sufficient grounds; but all these characters taken together form a remarkably compact assemblage, which places Neocrinus in a directly intermediate position between Cenocrinus and Comatula.” Two of the principal points of difference between Cenocrinus and Neocrinus have, however, no foundation in fact, while a third is, at most, one of specific value ; and the fourth, the supposed difference in the mode of 1 Sea Lilies, The Intellectual Observer, August 1864, p. 7. * Ibid., p. 10. 3 Proc. Roy. Soc. Edin., vol. vii., 1872, p. 766. 4 Sea Lilies, The Intellectual Observer, August 1864, p. 11. 280 THE VOYAGE OF H.M.S. CHALLENGER. life, is valueless. For individuals of Pentacrinus decorus have been found attached to telegraph cables by a spreading base ; and one specimen of Pentacrinus asterius at any rate, which I have seen, had the stem broken at a nodal joint, which was worn and rounded below, its central canal being closed up by a small median tubercle ; while this condition is common to several other Pentacrinide, as I have pointed out already (ante, pp. 18-22). Apart from the length of the internodes and the characters of the stem-joints, cirri, and arms, all of which are merely of specific value, the chief difference between Pentacrinus asterius and Pentacrinus decorus is in the mode of union of the two outer radials. In the latter type, as shown in Pl. XXXIV. figs. 3 and 5 (which were drawn under Sir Wyville’s own direction), these joints are united by a bifascial artieu- lation. But in Pentacrinus asterius (Pl. XII. figs. 18 and 21), and also in Pentacrinus miller’ and Pentacrinus wyville-thomson (Pl. XVIII. figs. 8, 11), there is a syzygy in this position. This difference, however, is one which occurs continually among the numerous species of the Comatulid genera. Antedon rosacea and Actinometra meridion- alis ave types of many species having the bifascial articulation; while Antedon fluctuans* and Actinometra solaris represent a smaller number of species which have the syzygy. I see no reason, therefore, for considering this difference as one of subgeneric value among the Pentacrinide, so as to separate Pentacrinus decorus, together with Pentacrinus blaker and Pentacrinus naresianus under a separate name, Neocrinus, from the other five species which have a syzygy between the two outer radials. Four of these, and probably Pentacrinus asterius as well, become free at a certain period of their life, just as Sir Wyville discovered to be the case in Pentacrinus decorus; so that one of the physiological characters on which he relied as giving Neocrinus an intermediate position between Penta- crinus asterius and the Comatulz is of much more general oceurrence than he supposed. The separation of Pentacrinus asterius and Pentacrinus decorus as types of sub- genera appears to have been abandoned by Sir Wyville within a year after he had proposed the name Cenocrinus for the former species. For in his well known memoir On the Embryogeny of Antedon rosaceus, published in the Philosophical Transactions for 1865, frequent reference is made to Pentacrinus (Neocrinus) asterias as well as to Pentacrinus (Neocrinus) decorus ; while Oersted’s species Pentacrinus miilleri was also referred to the subgenus Neocrinus. Sir Wyville seems, therefore, still to have regarded Pentacrinus briareus as having the first claim to the generic name Pentacrinus, although the Messrs. Austin had expressed an opposite opinion. He appears, however, to have eventually adopted their view, as all later writers have done. For in The Depths of the Sea reference is made to two West Indian species only, viz., Pentacrinus asterius and Penta- crinus miilleri ;? and neither Neocrinus nor Cenocrinus is mentioned, while Pentacrinus decorus is confused with Pentacrinus miillert. Subsequently also, when describing new 1 The specific formula of this type is—A.R. 3.2.2. 2 . 2 The Depths of the Sea, pp. 436, 442, 1873. , > REPORT ON THE CRINOIDEA. 281 “Porcupine” and Challenger species, Sir Wyville named them Pentacrinus wyville-thomsoni and Pentacrinus maclearanus; and the plate which was drawn under his supervision was lettered Pentacrinus asteria (Pl. X1.). We may therefore feel tolerably certain that Sir Wyville had recognised the inex- pediency of limiting the name Pentacrinus to the Liassic species only, though their generic differences from the recent Pentacrinidee had been noticed by him. We have seen that the name Cenocrinus, which was applied by Sir Wyville in 1864 to the classical species Pentacrinus caput-Meduse of Miller and Miiller, was afterwards dropped by him; but I cannot make out whether or not this arose from his becoming acquainted with the genus Cainocrinus which had been established twelve years pre- viously by Forbes.1 The essential difference between this type and Pentacrinus, as defined by Forbes, is that the pelvis or basal ring of Pentacrinus is “ composed of a single piece formed out of five anchylosed plates,” while that of Cainocrinus is ‘‘ formed out of five free plates.” These are seen in Forbes’s figure to compose a closed basal ring which separates the radials from the top stem-joint; and this is not the case with the basals either of Extracrinus or of Pentacrinus asterius, the only recent species known to Forbes. What Sir Wyville thought of Forbes’s genus I cannot say. He never referred to it, and the fact of his having himself proposed Cenocrinus as a subgeneric type looks rather as if he had not been previously acquainted with Cainocrinus. In any case, however, whether he knew it or not, he still referred to the same genus Pentacrinus, the species which was dredged by the “ Porcupine” in 1870, and was named after himself by his colleague Dr. Gwyn Jeffreys,’ F.R.S. ; and this is in all respects a true Cainocrinus with a closed basal ring (Pl. XIX. figs..6, 7; Pl XX. figs. 1-3). Quenstedt*® was unable to see any essential difference between Cainocrinus and Pentacrinus; but de Loriol,* writing about the same time, took a different view. Unaware of Forbes’s genus, he proposed to establish a new genus Picteticrinus for a fossil species of Pentacrinus presenting the then unusual character of a closed basal ring. But he subsequently discovered this to be a feature of the type described by Forbes as Cainocrinus, which he adopted as a generic name instead of Picteticrinus ;° and he referred to this type a species that had been originally supposed by Desor® to belong to von Meyer's genus Tsocrinus, which has been discussed above (ante, p. 271). Cainocrinus was regarded by de Loriol as establishing a transition between Millericrinus and Pentacrinus. He defines Pentacrinus as differ- 1 Monograph of the Echinodermata of the British Tertiaries, pp. 33, 34. 2 Proc. Roy. Soc. Edin., vol. vii., 1872, p. 767 ; and also The Depths of the Sea, p. 444. 3 Encriniden, p. 269. 4 Monographie Paléontologique et Géologique des Kitages Supérieurs de la formation J urassique des Environs de Boulogne-sur-Mer, 2™° partie, p. 297. 5 Swiss Crinoids, p. 111. ® Notice sur les Crinoides suisses, Bull. Soc. d. Sci. Nat. de Neuchatel, vol. i. p. 213. (ZOOL. CHALL. EXP.—PART Xxxi.—1884,) li 36 282 THE VOYAGE OF H.M.S. CHALLENGER, ing from Millericrinus in the verticillate arrangement of the cirri, and in having very small basals, which do not meet externally. Thus he says “ pieces basales fort petites, en général arrondies, non contigués et reposant sur les cinq angles de la tige.” On the other hand, Cainocrinus has a complete ring of basals like Millericrinus, but a stem with verticils of cirri like Pentacrinus. I cannot, however, regard this classification as satisfactory ; for even in those species of Pentacrinus which have an incomplete basal ring there is a great amount of variation in the extent to which the central ends of the basals are joined, and in the size of their outer ends which appear between the radials and the top stem-joimt (PL XI.; Pl XII. fig. 16; Pl XIIL fig. 1; Pl OVE exXave figs. 1,2; Pls. XXVIII, XXIX.; Pl. XXX. figs. 1,4; Pl. XXXI figs. 1,2; Pl. XXXIV. figs. 1,8; Pls. XXXV., XXXVI. ; Pl. XXXVIL. figs. 1,2). I have elsewhere stated my reasons for not adopting Cainocrinus as a genus distinct from Pentacrinus ;' and the results of my examination of the large series of Pentacrinidee dredged by the Challenger and the “ Blake” Expeditions has only served to strengthen my opinion. It must be remembered that the question of the more or less perfect closure of the basal ring simply has reference to its appearance on the exterior of the calyx. The inner ends of the basals always meet one another around the neurovascular axis. But they are sometimes not in contact by the whole length of their sides, so that their outer ends appear to be separated by the radials (compare Pl. XII. figs. 1, 2,16; Pl. XIII. fie; Ws Ply ROR ese eas PIOKX. figs: 123; PL XXXVI. fig, 1; Pl) Xe figs) 4s Pl REVS fear si PL XXXVI). The closure of the basal ring, therefore, is so extremely variable within specific limits that it scarcely affords characters of specific, much less of generic value. So far as the fossil species are concerned, however, it is quite possible that the more or less perfect closure of the basal ring on the exterior of the calyx may afford characters of some systematic value. But I strongly suspect that the examination of a large series of specimens would indicate a very great variability in the size of the basals, just as in the recent types. The unique specimen of Pentacrinus maclearanus (P\. XVI.) has a closed basal ring, and would therefore be called a Cainocrinus by de Loriol. In Pentacrinus wyville- thomson there is sometimes a very close union between the pentagonal basals as in Pl. XIX. figs. 6, 7, and Pl. XX. figs. 1-3 ; while in other specimens the basals are more triangular in shape and less closely united, as is shown, with a little exaggeration, in Pl. XVIII. figs. 1, 2. It occasionally happens that one or two of the basals fail to meet their fellows, but the ring is always more or less complete. Variations of a similar kind, though greater in degree, are presented by Pentacrinus alternicirrus. Some individuals have prominent, rhomboidal basals not meeting laterally, like those of Pentacrinus asterius (Pl. XIII. fig. 1); while im others they are much less 1 Journ. Linn. Soc. Lond. (Zool.), vol. xv. p. 210; and Bull. Mus. Comp. Zodl., vol. x., No. 4, p. 168. REPORT ON THE CRINOIDEA. 283 prominent and triangular or pentagonal in shape (Pl. XXV.). The same difference appears in Pentacrinus miilleri. The specimens in the Copenhagen Museum, one of which is figured by Liitken,’ have a closed ring of pentagonal basals. Some of those dredged by the “ Blake” are in the same condition; but this is far from being the case in the three individuals figured in Pl. XIV. and in Pl. XV. figs. 1, 2. Sir Rawson Rawson’s specimen (Pl. XV. fig. 1) has the smallest basals that I have yet seen in this species ; while I have met with all intermediate stages between this condition and that of Oersted’s types at Copenhagen. There is also a certain amount of variation in Pentacrinus blake, though | have not seen a sufficient number of specimens to be able to say much about it. In Pentacrinus naresianus, again, some individuals have pentagonal basals forming a closed ring ; while in others the basals are triangular and barely meet their fellows. But as a rule their outer ends are comparatively small and separated by the radials, which are sometimes prolonged slightly downwards over the upper stem-joints (Pl. XXVIII. fig. 1; Pl. XXX. fig. 1). A few specimens exhibit both conditions, some of the basals meeting their fellows, while the rest are separated by the downward projecting radials. But the most remarkable variations in the development of the pieces of the basal ring occur in Pentacrinus decorus. They are sometimes smaller than those of Penta- crinus asterius, and scarcely more conspicuous than the interradial ridges on the stem beneath them (Pl. XXXIV. figs. 1, 8; Pl. XXXV.; Pl. XXXVI. fig. 3); or they may be larger rhomboidal knobs standing out prominently from the general plane of the calyx, and meeting one another by their extended lower angles (Pl. XXXVI. fig. 1; Pl. XXXVII. figs. 1, 2); or they may present any intermediate condition between these two. To some extent these differences are perhaps due to age, both the individuals figured on Pl. XXXYV. being very young. But those represented in Pl. XXXVI. are apparently of about the same age, so far as can be judged from the characters of the stem, while their basals are at the two extreme stages of development; and the original of Pl. XXXIV. fig. 1 is very far from being a young individual! In the young Pentacrinus wyville-thomsoni, again, the basals are of about the same relative size as they are in the adult (Pl. XVIII. figs. 1-3). I do not, therefore, see any reason for regarding the variations in the development of the basals as of any more importance than the differences in the number of arm-divisions. In Actinometra parvicirra the number of arms may vary from thirteen to thirty-nine, and much the same is the case in some species of Pentacrinus and Metacrinus. But these differences are rarely of specific, and much less of generic value; and in the same way I find it impossible to consider the presence of a closed basal ring as a valid generic character separating Cacnocrinus from Pentacrinus. There is no recent Pentacrinus in which the basals do not appear upon the exterior of the calyx, so as to separate the radials either wholly or partially from the 1 Om Vestindiens Pentacriner, loc. cit., Tab. iv., v., figs. 1, 2. 284 THE VOYAGE OF H.M.S8. CHALLENGER. top stem-joint. A few fossil species, however, have been figured or described as not possessing any external basals. Two of these are from British rocks, Pentacrinus fisheri and Pentacrinus dixont. The former was described by Baily,’ who was unable to detect the presence of interradial basals, and was led therefore to regard the first radials as basals. True basals are really present, however, and may be seen in the original specimen in the Dorchester Museum, or in another found subsequently and now in the possession of Mr. Damon of Weymouth. The same is the case with the specimen of Pentacrinus dixoni in Mr. Willett’s collection at Brighton, which was figured in Dixon’s Geology of Sussex (1878 edition, pl. xix. fig. 22). In both these species, therefore, the supposed absence of basals is really due to error; and I think it likely that the same may be true both of Isocrinus pendulus, von Meyer, and of the Forest Marble specimen from Farley in Wiltshire, which was described by Goldfuss? as Pentacrinus scalaris; and also of Pentacrinus penta- gonalis personatus from the Brown Jura. According to Quenstedt * three pieces rest on the top of the stem “ womit jedes der 5 Hauptradiale beginnt.” But neither then nor in the Eneriniden did he make any comment on the absence of basals, though he must have noticed it. They may perhaps be small and only just in contact by their central ends, so that they are concealed beneath the radials, as sometimes happens in Fnerinus and in the fossil Comatule.* But it appears to me improbable that the embryonic basals of any Pentacrinus should have undergone transformation into a rosette, as those of many Comatule do, A Stalked Crinoid with a rosette would be a novelty indeed. One would greatly like to know the real condition of the anomalous specimen of Metacrinus costatus represented in Pl. XLIX. fig. 2, which has no basals visible externally. They are generally so very well developed in this genus that their absence altogether seems unlikely ; and I suspect therefore that they are quite small and concealed between the top stem-joint and the radial pentagon, as in the case of Hucrinus and the fossil Comatule. It is a curious fact that there are so very few species of Pentacrinide with only one ray-division, 7.e., with only ten arms; while at the same time the number of arms rarely reaches the large total of one hundred or more, as it does in some of the giant species of Actinometra from the Philippines. In Pentacrinus maclearanus (Pl. XVI.), Pentacrinus wyville-thomsoni (Pls. XVII, XIX.), Pentacrinus alternicirrus (Pl. XXV.), Pentacrinus blake: (Pl. XXXI.), and Pentacrinus decorus (Pls. XXXIV.-XXXVIL), the rays may divide three times, t.e., there may be distichal and palmar axillaries above the radials. * Description of a new Pentacrinite from the Kimmeridge, cf. Oxford Clay of Weymouth, Dorsetshire, Ann. and Mag. Nat, Hist., ser. 3, vol. vi. pp. 25-28, pl. i. ? Petrefacta Germanie, vol. i, pl. lx. fig. 10. 3 Der Jura, 1858, pp. 363, 364. 4 Journ, Linn. Soc. Lond. (Zool.), vol. xv. p. 195, pl. ix. fig. 6. : REPORT ON THE CRINOIDEA. 285 This would give the maximum number of arms as forty ; but although the ten distichal axillaries may all be present, the palmar axillaries are frequently only developed on the two outermost of every set of four secondary arms, as in the unique specimen of Penta- crinus maclearanus (Pl. XVI.), and the individual of Pentacrinus alternicirrus shown in Pl. XXV. This would give six arms on each ray, making thirty in all. Sometimes, however, there are no palmars at all, or only one or two series of them (Pl. XVIII. fig. 2; Pl. XIX. figs. 1, 6, 7), so that the number of arms varies between twenty and thirty. The ray-divisions of Pentacrinus decorus present almost as much variation as the basals do. Some young specimens have only one or two distichal series (Pl. XXXV.); while one individual has but ten arms like Pentacrinus naresianus. In others, again, the arms are more numerous, though palmars are rare (Pl. XXXVI fig. 1). I am inclined to suspect, from an examination of several young specimens, that the many-armed condition is to some extent a secondary one. Thus if none of the arms were broken and subsequently repaired, the original of Pl. XXXYV. fig. 1 would have grown up with no more than eleven arms. When, however, an arm is broken off at a syzygy, and a new one developed in its place, an axillary is nearly always formed in this new one sooner or later, whether there were one present on the original arm or not. An instance of this kind is shown in Pl. XXXVI. fig. 2; and it is not uncommon to meet with indi- viduals of ten-armed species of Comatula which have replaced some of their arms after fracture and have developed axillaries in the reparation, so that the number of arms may reach eleven or twelve. This inerease in the number of arms after reparation seems to take place largely in Pentacrinus decorus ; for it is rare to meet with a specimen which does not show these signs of reparation, certain axillaries and the arms which they bear being distinctly smaller than their fellows. In Pentacrinus asterius and Pentacrinus miilleri there are always twenty arms or more, all the primary arms ending in distichal axillaries. Most of the secondary arms bear palmar axillaries, and there are sometimes even one or two more beyond these, so that the rays may divide five times in all. There is no special regularity of division in Pentacrinus asterius, though the number of arms is large, exceeding one hundred, according to Sir Wyville Thomson.’ But in Pentacrinus miilleri there are usually not more than four ray-divisions, the (palmar) axillaries beg limited to the outer arms as in Pentacrinus maclearanus and Pentacrinus alternicirrus; while the fourth and fifth axillaries, if present, occupy a similar position, so that there are six, eight, or ten arms to the ray, as 2,1; 1, 2—2,1,1; 1,1,2—or 2,1,1,1; 1,1,1, 2. The arms of Metacrinus branch as a rule more freely than those of Pentacrinus, except Pentacrinus asterius, all of the species having two, and most of them four axillaries beyond the radials; but there is no special regularity about the grouping of the arm- divisions. 1 Sea Lilies, The Intellectual Observer, August 1864, p. 5. 286 THE VOYAGE OF H.M.S. CHALLENGER. Among the recent Pentacrinide there is but one solitary example of a uniformly ten- armed type, which embraces a majority of the species of Antedon. This is Pentacrinus naresianus, represented in Pls. XX VIII.—XXX. Owing to the fragmentary condition in which many of the fossil Pentacrinidee occur, it is impossible to say much about the nature of their arm-divisions. But in Penta- crinus beaugrandi, de Loriol,’ sp., the remains of the primary arms bear no axillaries up to the twelfth jomt from the radials; while eleven simple joints are still preserved in the specimen from the Lias of Vaihingen, which is referred by Quenstedt to Pentacrinus tuberculatus.” Reference has already been made to the low state of development of the arms of recent Pentacrinide as compared with those of Comatulee (ante, p. 55). They are fewer in number (7.e., when multiradiate forms are compared), and have both pinnules and ambulacral plating less developed towards their ends; while the number of joints separating successive axillaries is far more variable within specific limits, and does not seem to have become tolerably fixed as is the case in the Comatule. Singularly enough, the two species Pentacrinus wyville-thomsoni and Pentacrinus alternicirrus, in which the distichal and palmar series are most uniform, are the very ones which most resemble the Comatulee in their mode of life (ante, p. 19). It is curious that in the Pentacrinidee and Apiocrinidee the external appearance of the arm-joints should be so much more constant than it is among the Comatule. In the latter family the arm-joints may be saucer-shaped, more or less sharply wedge-shaped, &c., and it is in many cases easy to identify a species from detached portions of the arms, especially as there is also very considerable variation in the characters of the pinnules. But both in Pentacrinus and in Metacrinus there is a very great sameness, not only in the form of the arm-joints as seen from their dorsal side, but also in the appearance of the pimnules which they bear. The tubercular projections on the pinnule-joints of Pentacrinus asterius (Pl. XIII. figs. 1, 14), and the indications of carination on the pinnules of a few species of Metacrinus, are almost the only variations in the character of the pinnules through all the recent species of the family. It is true that the features of the lower pinnules of Metacrinus are such as to afford a character of some generic value for separating it from Pentacrinus. But with the exceptions above mentioned the pinnules of all the different species of Metacrinus are very much alike. Both in this genus and in Pentacrinus the arm-joints are almost invariably of the transversely oblong type (Pls: XT, XIV.; PL XV, figs. 2, 3; Pl: XVI; gee eile fies: 13 exes figs. 1, 6, 75 °Pls. XXV., XXXVI, XXXVING) DER eX EIEN va ei vais XLIX., LII.); and the same is the case in most, if not all, of the fossil species. It is therefore at first sight by no means easy to identify the species to which isolated 1 Monographie des Etages Jurassiques Supérieurs de Boulogne-sur-Mer, 2™° partie, p. 298, pl. xxxvi. fig, 23, a. 2 Encriniden, Tab. 97, fig. 39. -_ REPORT ON THE CRINOIDEA. 287 arm-fragments belong. But as I have pointed out above, the peculiarities of the arm- grooves upon the ventral surface of the skeleton, and their relation to the ambulacra, afford characters of considerable systematic value. The joints of Pentacrinus naresianus, however (Pls. XXVIII, XXIX.; Pl. XXX. figs. 1, 23), show a distinct indication of the more oblique shape which is common among the Comatule; while both in this species and in Pentacrinus blakei the peculiar nature of the syzygial union renders the arms very readily distinguishable (Pl. XXX. fig. 23; Pl. XXXa. figs. 9-12; Pl. XXXI. figs. 1; 25) PEON figah 53/7012; 14): The characters of the stem of the Pentacrinidee have already been fully discussed (ante, pp. 12-23). The fact that during growth it undergoes rather considerable modifi- cations in its appearance has led to a very general belief in the impossibility of identifying species by means of stem-fragments only. This is more especially the case as regards the fossil species, which are often based upon the stem-characters alone, since calyces are but rarely:met with; and I think it not improbable that two or even more types of stem from the same horizon, to which different specific names have been given, may sometimes be only different stages of growth of one and the same species. Thus, for example, four species might be made out of the joints represented in Pl. XXII. figs. 13, 14, 23, and 26, which are, however, merely different stages of growth in the stem of Pentacrinus wyville-thomsoni. But on the other hand, the difference between the stem-fragments figured on PI. XIII. fig. 8 (Pentacrinus asterius) and Pl. XIX. fig. 4 (Pentacrinus wyville-thomsoni) are obviously not due to any developmental causes ; and the two would be universally recognised as belonging to different species, even if nothing whatever were known about the calyces and arms belonging to them. The same remark holds good in the case of Metacrinus, isolated stem-fragments of Metacrinus alternatus (Pl. XXXIX, fig. 3), Metacrinus cingulatus (Pl. XLI. fig. 1), and Metacrinus nobilis (Pl. XLI. fig. 5), to say nothing of other species, being very readily recognisable. What has been written above refers simply to the general appearance of the stem- fragments ; but when the number of internodal joints is taken into consideration, and also the markings on their terminal faces, the characters of the stem as'a whole must be regarded as of very considerable systematic value. The stem-joints of Balanocrinus and Extracrinus are very readily identified by the sculpture on their faces; but as far as the internodal joints are concerned, I am unable to find any constant difference in this respect between Pentacrinus and Metacrinus. In most (recent) species of both genera there are from three to six strongly marked ridges along the sides of each petaloid figure. The proximal ridges joi their fellows in each interpetaloid space, while the outer ones reach the exterior and cause the crenulation along the line of union between every two joints, the ridges of each face alternating in position with those of the face opposite to it (Pl. XIII. figs. 10, 11; Pl. XXII. figs. 22-24; Pl. XXVI. fig. 17; Pl. XXX. figs. 25-30; 288 THE VOYAGE OF H.M.S. CHALLENGER. Pl. XXXVI; Pl. XXXVII. fig. 22; Pl. XXXIX. figs. 4, 7-11; Pl. XLI. figs. 1-3, 5-8, 15-17; Pl. XLV. figs. 2,4; Pl. XLVIL figs: 1-9; Pl. XLIX: figs. 3=5). The same characters may be seen in the numerous Pentacrinus joints figured in Tabs. 97-99 of the Encriniden, and on pls. xiv.—xvil. of de Loriol’s Swiss Crinoids. In some of these fossil joints the number of ridges at the sides of the petaloid figures may sometimes reach eight or ten; but the inner ones always meet their fellows in the interpetaloid spaces, while the outer ones appear externally. This is not the case in Extracrinus, which has a more extensive but smaller crenulation at the sides of the linear petals, as pointed out already (ante, p. 276). In the recent species of Pentacrinus the cirrus-socket may extend downwards below the articular surface so as to encroach very considerably on the internodal joint beneath it, asin Pentacrinus naresianus and Pentacrinus decorus (Pl, XX Xa. fig. 6; Pl. XXXVI), and in a less degree also in Pentacrinus miilleri and Pentacrinus blakei (Pl. XXXL. fig. 3); or the joint above the node may be slightly incised to receive the upper part of the socket, as in Pentacrinus alternicirrus (Pl. XXVIL. fig. 1), Pentacrinus wyville-thomsoni (Pl. XIX. figs. 3, 4), and occasionally also in Pentacrinus asterius. But m these cases the alteration of the supra-nodal joint is not very considerable. Among the Pentacrinus species it is most marked in Pentacrinus wyville-thomsoni (Pl. XXII. fig. 17). With the exception of those on the lowest nodal joint the cirri of this type are often found directed upwards (Pl. XIX. fig. 1), while in others like Pentaerinus miilleri, Pentacrinus maclearanus, Pentacrinus naresianus, Pentacrinus blake, and Pentacrinus decorus they are directed downwards (Pls. XIV., XVI., XXVIII., XXIX., XXXI., XXXIV.), and their bases are received in the hollowed sides of the infra-nodal joints. On the other hand, the tendency of the cirri of Metacrinus is to take an upward direction, the supra-nodal joints being slightly incised to receive their bases. This is well shown in Metacrinus angulatus (Pl. XXXVIII.; Pl XXXIX. fig. 9), Metacrinus cingulatus (Pl. XL.), Metacrinus wyvillii (Pl. XLVIII.), Metacrinus costatus (Pl. XLIX. figs. 1-3), Metacrinus interruptus (Pl. LII.), and) Metacrinus tuberosus (Pl. LIIL. figs. 1,2). In some species, such as Metacrinus varians (Pl. XLIV.), this character is not very prominent ; but it can be traced with more or less distinctness in all the species of the genus that I have seen, and is therefore (as far as it goes) of considerable value in the separation of Metacrinus from Pentacrinus, as in the case of Metacrinus tuberosus (Pl. LIL figs. 1-6) and Metacrinus stewarti,’ of which only the stems are known. But I have been unable to apply it to the determination of any fossil species, as this point is naturally but rarely illustrated in sufficient detail in the figures of Quenstedt and de Loriol. 1 On Three New Species of Metacrinus, Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. ii. p. 443. REPORT ON THE CRINOIDEA. (09) © B. On the Characters of Young Pentacrinide. Young individuals of Pentacrinus are naturally rare, as is only to be expected. It is related, however, that on one occasion a large number of them of all ages and sizes were thrown up on the shore at Barbados after a gale; but unfortunately for science no one on the spot had knowledge enough to recognise the value of this extraordinary event, and a great opportunity, such as may never occur again, was therefore lost. Nevertheless the discovery that recent Pentacrinid flourish in great numbers on certain parts of the sea-bed, like their predecessors in the Liassic and Jurassic Seas, has brought about a considerable increase in our knowledge of their premature stages of growth. The dredgings of the ‘“ Porcupine,” Challenger, and “Blake” have yielded several young individuals of three Pentacrinus species and of Metacrinus nodosus, some of which are figured on Pls. XVITI., XXXa., XXXV., and LI. Like the young Comatula, they are all distinguished by the relatively great height of the first radials as compared with those of the adult, which are wider than high, often considerably so (Pl. XIX. figs. 1, 6, 7; Pl. XXX. fig. 1; Pl. XXXVII. figs. 1, 2; Pl. L. figs. 1, 5), while the radials of the young individuals are spade-like, to use an expressive term introduced by Sir Wyville Thomson. This is naturally most marked in the youngest specimen with a total length of 80 mm. (compare Pls. XXXYV. and XXXVIL.); and the cup with its small basals presents a singular resemblance to that of Plicatocrinus and Bathycrinus (Pl. VII. figs. 1-8, 6; Pl. VIIla. fig. 1). The little we know of the former, however, shows that it is a totally aberrant type, and the resemblance must therefore be considered as in great measure accidental and not as indicating any genetic relationship. But Bathycrinus is a decidedly embryonic form, as is shown by the length of all its three radials and the absence of pinnules from the arm-bases. /Hyocrinus (Pl. VL) is another type with high spade-like radials; but the basals are of the same character, and not small and inconspicuous as in young Pentacrinidee and in Bathycrinus, while the arms are totally different. Another character of the incompletely developed Crinoid, which is very marked in Rhizocrinus and Bathycrinus, and still more so in the aberrant Plicatocrinus and Hyocrinus, is the comparative freedom of the second radials. In many Comatule they are closely united laterally; while in most of the Paleocrinoids, as in Apiocrinus and Guettardicrinus, they are practically immovable, and enter into the composition of the body. The second radials of Pentacrinus, however, rarely show any traces of the lateral pits lodging interradial ligaments such as occur in many multiradiate Comatule. But they are often in very close apposition, while in young individuals of the same species they are comparatively free (Pls: XVIIL., XIX., XXIX., XX Xa, XXXV.,, XXXVIL). The arm-joints of most young Crinoids, as well as those in the outermost and growing parts of the arms of more mature individuals, are always distinguished by (ZOOL, CHALL. EXP,—PART XXXIL—1884,) hi 37 290 THE VOYAGE OF H.M.S. CHALLENGER. the relatively great proportion of length to width, whatever may be the shape of the full- grown joint. In some Comatule this condition is permanently retained, but in others and in the Pentacrinidz the arm-joints of mature individuals are usually much wider than long. In accordance with this, we find that even in young individuals of Pentacrinus decorus with quite high radials and arms only 12 mm. long, consisting of about a dozen properly formed joints, the great relative width of the latter is already very distinctly indicated (Pl. XXXYV.); while the last few joints are much smaller than their predecessors, and have rather the appearance of a pinnule than of the continuation of the arm, the preceding joint of which looks like an axillary bearing two small arm-stumps. This mode of development is less marked in a somewhat older individual of Pentacrinus decorus with about forty arm-joints, the later ones of which gradually decrease in size instead of becoming abruptly smaller; and the imperfect state of development of the later pinnules which is so characteristic of the Pentacrinide is very well shown. This would seem to indicate that the mode of growth of the arm-bases proceeds on a different plan from that of their middle and outer portions. In still larger individuals, as in the youngest specimens of Pentacrinus wyville-thomsoni (Pl. XVIIL. fig. 3), Pentacrinus naresianus’ (Pl. XXXa. fig. 1), and Metaerinus nodosus (Pl. LI. fig. 1), the terminal arm-joints are distinctly longer than wide, although the lower ones have almost assumed their adult form; and in all of them, but especially in Metacrinus nodosus, there is the characteristic reduction in the size of the later pinnules. Nothing is to be learnt regarding the order of the pinnule-succession in the Pentacrinidz from any of these young individuals; for the smallest of them are larger than some young Comatulee already detached from the stem, but without pinnules on the arm-bases, and they all have their proper complement of pinnules. The stem-joints of the immature Pentacrinide, like the later joints of growing arms, are relatively high in proportion to their width. This is exactly the reverse condition to that of the young joints formed immediately beneath the calyx (Pl. XXXIV. fig. 9). The same distinction appears in the very different type of stem characteristic of the Comatula-larva and of the Bourgueticrinide (Pl. VII. fig. 11; Pl. VIIa. fig. 1; Pl LIII. figs. 7, 8). The young joints are at first discoidal, then lengthen out, and finally the width increases relatively to the length so as sometimes even to exceed it considerably. The two types of stem are so very different that it is perhaps a little rash to reason about the one on the basis of the other. The interealation of new joints, which is so characteristic of the Pentacrinide, seems never to occur in the Bourgueticrinide, new joints being only formed beneath the calyx. In this last respect, however, the mode of growth in the youngest Pentacrinide with very slender stems appears to be very much what it is in the equally slender Rhizocrinus and Bathycrinus. But as the diameter of the stem increases to 3 or 4 millimetres the 1 The arm-joints of this species are more like those of the Comatule than is the case in any other Pentacrinus. Instead of being nearly oblong, they have somewhat oblique ends, especially in the lower parts of the arms (Pls. XX VITI.-XXX.). REPORT ON THE CRINOIDEA. 291 length of the joints does not increase in the same proportion ; and I am therefore not surprised at having met with but one individual in which the stem-joints are longer than wide, as shown in Pl. XXXV. fig. 1. A comparison of the figures on this plate, which represent the two youngest individuals dredged by the “ Blake,” with those of the older, but still immature forms figured in Pl. XXXVL, will show, however, that the great relative height of the stem- joints is a very characteristic feature in the development of Pentacrinus decorus. The same feature is apparent in Pentacrinus wyville-thomsoni (Pls. XVIII, XIX.), Pentacrinus naresianus (Pl. XXVIIL; Pl XXXa. fig. 1), and Metacrinus nodosus (Plobetis. 33 Pl Lidge), The sculpture on the terminal faces of these internodal joints of young individuals (Pl. XXXa. figs. 2,3; Pl. XXXVII. fig. 9; Pl. LI. figs. 2-5), as in the case of those intercalated between the pre-existing joints in other stems (PI. XXII. figs. 3-12; Pl. XXXVIL. figs. 10, 13, 14), is more or less obscure; but the petaloid markings are evident from the first, as might be expected. The external appearance of the nodal joints not unfrequently alters considerably during growth. Thus, for example, in Pentacrinus decorus the characteristic expansion down to the upper edge of the cirrus-socket (Pl. XXXVI.) scarcely appears at all in the young nodal joint (Pl. XX XVII. fig. 5); while in Pentacrinus naresianus there is a trace of this expansion in the young stem, though it entirely disappears in the adult. In Pentacrinus wyville-thomsoni, again, the overlap of the lower edge of the cirrus-socket above the infra-nodal joint is far less evident in the young stem (PI. XVIII. fig. 3) than it is in the adult (Pl. XIX. figs. 3, 4). In Metacrinus nodosus, however, the characteristic enlargement of the nodal joints between their cirrus-sockets is very evident in a young stem with relatively high joints (Pl. LI. figs. 6, 7). C. The Calyx and its Contents. The calyx, 7.e., the combined ring of basals and radials, is constituted in the same way in both the living genera of Pentacrinide, viz., Pentacrinus and Metacrinus, as is evi- dent from a glance at Pl. XII. The former may therefore be taken as the type; for it is the better known genus, and has a long geological history, while Metacrinus is not yet known to occur in the fossil state. The calyx of Pentacrinus, while more like that of ordinary Comatule, @.e., Antedon, Actinometra, and Eudiocrinus, than the corre- sponding part is in Rhizocrinus and Bathycrinus, nevertheless differs from it in a very important character. This is the presence of unmetamorphosed basals, such as are only found in Atelecrinus and Thawmatocrinus (Pl. LVI. figs. 1-4) among Comatule ; for the embryonic basals of the ordinary types undergo the well known transformation into a rosette. This structure covers in the chambered organ which is lodged within the 292 THE VOYAGE OF H.M.S8. CHALLENGER. cavity of the centro-dorsal (Pl. LXI. fig. 2), and the same is the case with the flattened basals of Atelecrinus. The chambered organ of Pentacrinus is both relatively and absolutely smaller than that of Comatula, and the reason for this is obvious. The Comatulid centro-dorsal represents, as it were, a coalesced series of the nodal stem-joints of Pentacrinus, and the five cavities of the chambered organ lodged in its upper part are each in connection with one cirrus-vessel only. But the remaining cirri which are borne by the centro- dorsal in greater or less abundance are supplied by a number of vessels that come off below the chambers. Within the dorsal portion of the chambered organ, “lying at the bottom of the centro-dorsal basin, there is a succession of verticils of five triangular leaflets, increasing in size from below upwards, from the extremities of some of the upper of which leaflets issue groups of three diverging cords that proceed to the cirri. I can scarcely doubt that these verticils mark the origins of the earlier cirral cords from the Crinoidal axis; and this obviously suggests that the five-chambered organ is itself only another and larger verticil, which has come by the formation of ventricular cavities in its substance (analogous to the lateral ventricles of the brain), to occupy the whole cavity of the enlarged centro-dorsal basin.”* In Pentacrinus, however, the cirri all come off from the nodal joints of the stem, where the five downward prolongations of the cavities of the chambered organ in the calyx enlarge and each gives off a cirrus- vessel (Pl. XXIV. figs. 3, 4, chn). No cirrus-vessels come off from the enlargement of the vascular axis within the calyx, which represents the chambered organ of Comatula without the verticils of cirrus-vessels below it. The chambers, however (Pl. XXIV. figs. 6-8, ch), ‘are scarcely larger than the nodal cavities in the stem from which the cirrus-vessels arise,” and are much smaller than the corresponding chambers within the upper part of the centro-dorsal of Comatula (Pl. LXI. fig. 2), which give off the vessels to the younger cirri. In fact they are sometimes almost equalled in size by the central vessels within the ring of chambers, as seen in Pl. XXIV. fig. 6. They are not closed below as is practically the case in the Comatulze, nor do they present as sudden enlarge- ments of the stem-vessels as in Fhizocrinus and Bathycrinus; but these vessels are, as it were, permanently enlarged in the upper part of the stem, owing to the closeness of the nodal joints which are successively formed beneath the calyx, and are only gradually separated by the intercalation of internodal joints between them. The chambers of Pentacrinus therefore taper very gradually downwards into the stem-vessels, and it is difficult to say where the latter begin and the former end (Pl. LVIII. fig. 3). The primary Y-shaped interradial cords which come off from the fibrillar envelope surrounding the chambered organ of Pentacrinus (Pl. XXIV. fig. 7; Pl. LVIIL figs. 1, 3—a.7.) sometimes bifurcate before entering the basals. On the inner face of the See W. B. Carpenter, Proc. Roy. Soc., vol. xxiv., 1876, p. 219. Compare Pl. XXIV. figs. 3, 4, 6, which are all equally magnified. 1 2 — REPORT ON THE CRINOIDEA. 293 basals of Pentacrinus decorus there is but one central opening, so that the primary cords fork within the basals (PI. LVIII. fig. 1) as they did in Apiocrinus. But in Pentacrinus blake: this opening is widely extended laterally, while in Pentacrinus naresianus, Penta- erinus alternicirrus,' and especially in Pentacrinus wyville-thomsoni (Pl. XXI. fig. 7a), it 1s more or less completely divided into two by a vertical partition. In Pentacrinus asterius and Metacrinus angulatus, both of which, and especially the latter, have large basals with a great development of calcareous network on the upper ends of their inner faces, the opening of the central canal is pretty distinctly double. On the upper surface of the basals the openings are, of course, perfectly separate. They are situated on either side of the median ridge, and correspond to similar openings on the under surface of the two contiguous radials which partly rest upon each single basala (ily Nuleshes pbleg ta 225 25); Pho XVI. figs: 95, 7; Pl. XX. figs. 2, 3; 6; 9); PEDO hes, 60, 0).¢,and 7,0; Pl. XXVI. fio. 9; Pl) XXX. figs. 5;7,8; Pl XXXL fig. 5; Pl. L. fig. 5). In most specimens of Pentacrinus wyville-thomsoni, as in other Pentacrinidz, removal of the basals exposes the apertures on the lower surface of the radials where the secondary axial cords enter them, together with the lowest portion of the central plug (Pl. XX. fig. 9). But in one individual of Pentacrinus wyville-thomsoni Dr. Carpenter found this plug to be somewhat unusually developed. Its lower surface forms a tolerably well defined pentagonal plate, the angles of which are interradial in position (Pl. XX. figs. 4, 5, 6, 8). It lies between the basals and radials, and is pierced in the centre for the passage of the plexiform gland rising out of the chambered organ, together with openings through which the secondary axial cords passed on their way from the basals to the radials, the apertures in the latter plates bemg entirely concealed by it. The radials of Pentacrinus thus differ very considerably from those of Comatula, for the proximal openings of their central canals are really on their dorsal faces, viz., at the central ends of what I have called the inner dorsal surface, 7.e., that part which rests on the basals (Pl. XII. figs. 11, 22; Pl. XX. fig. 9; Pl. XXI. figs. 6a, 6b, 6c; PI. L. fie. 5); whereas in the Comatule, as I have shown elsewhere,’ these openings are on the inner faces of the radials, 7.e., those which form the walls of the radial funnel that con- tains the plexiform gland rising from the chambered organ. They are also less closely approximated in Pentacrinus than in Comatula, one being situated on either side of the strong crest which divides the inner dorsal surface into two lateral halves, instead of being only separated by a very delicate calcareous bar. The converging axial cords which enter these openings on the radials of Pentacrinus (Pl. XXIV. figs. 7-9; Pl. LVIII. figs. 1-3—ar’) run upwards and outwards for some little way before they are united by the imterradial and intraradial cords to form the circular commissure 1 T have only seen single specimens of the dissected calyx in these three species. 2 Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. ii. p. 78, pls. iv.—vii., 1877. 294 THE VOYAGE OF H.M.S. CHALLENGER. (Pl. XXIV. fig. 9, 2co, cco). The canal in which this is lodged is never close down to the proximal openings in the inner or dorsal face, as it is in all Comatule, even Atele- crinus. But its position varies somewhat in different species. Thus, for example, it comes nearer to the edge of the central funnel in Pentacrinus decorus (Pl. XXXII. fig. 5) than in Pentacrinus wyville-thomsoni (Pl. XX. fig. 6). The double axial cords of the rays which proceed outwards from it resemble those of Comatulz in their very close approximation. Small portions of them, cut very obliquely, are seen in Pl. XXIV. fic. 9, A. They are lodged close together in the same canal as far as the axillary radial, not being so widely separated as in Enecrinus; and the arrangement of the commissures in the axillary is just the same as was discovered by Ludwig in the Comatule. D. The Geological History of Pentacrinus. Excepting for some doubtful forms from the Eifel, the earliest known Pentacrinidee occur in the ‘“ Wellenkalk” of the Jura, at an horizon somewhat lower than the well- known limestone in which Encrinus liliiformis occurs. According to Quenstedt, both generic types occur together in the Wellenkalk of Wiirtemberg; and he refers all the Pentacrinide to one species, Pentacrinus dubius, though they have received various other names, both generic and specific, from earlier writers. Nothing being known of them but fragments and isolated joints of the stem, any detailed classification of them is hardly possible. But the similarity of the stem-fragment from Waltershausen' with ten cirrus-whorls at intervals of eight or ten joints, to the stems of recent Pentacrinide, is very striking. This resemblance was noticed by von Schlotheim,’ who described the fossil as Pentacrinus vulgaris, and referred to the same type the recent specimens of Guettard and Ellis. Some years later Quenstedt’® gave an excellent figure of it; but in the absence of an associated calyx he hesitated to refer it to Pentacrinus as von Schlotheim and Goldfuss had done, and so described it as Encrinites dubius. Beyrich and later writers, however, have generally regarded it as a Pentacrinus, as Quenstedt himself has done in the Encriniden, and the reference of the fossil to the Pentacrinidee will now be scarcely disputed. Another very similar stem from the Muschelkalk of Silesia was described by von Meyer* as Chelocrinus acutangulus. This genus was established to receive certain forms with more than ten arms, owing to the presence of distichal and palmar series, which had been generally referred to Encrinus. It has been abundantly proved, however, by the researches of von Strombeck’ and others, 1 Encriniden, p. 198, Tab. 97, figs. 14-22. * Die Petrefactenkunde, p. 327. 5 Ueber die Encriniten des Muschelkalks, Archiv f. Naturgesch., Jahre. i. Bd. ii., 1835, p. 225, Taf. iv. fig. 2. * Fische, Crustaceen, Echinodermen und andere Versteinerungen aus dem Muschelkalk Oberschlesiens, Paleeonto- graphica, Bd. i., 1851, p. 272. ® Ueber Missbildungen von Encrinus liliiformis, Lam., Paleontographica, Bd. iv., 1856, p. 176. REPORT ON THE CRINOIDEA. 295 that the character on which von Meyer established Chelocrinus is one of no systematic value whatever. One of the two species on which he founded the genus was the Encrinus pentactinus of Bronn.* This name was proposed for a single specimen which presented a very remarkable combination of characters. The cup appears to be that of a typical Zncrinus with some twenty biserial arms. The stem has a rounded pentagonal outline, and consists of about twenty-five joints, some of which bear verticils of five cirri. Beyrich appears to consider these characters as of altogether subordinate value, for he says’—‘‘die etwas abweichende Form des fiinfseitigen Stengels mit deutlich eingesenkten Seiten kann eben so wenig fiir ein unterscheidendes Artmerkmal gelten, wie die von Bronn beobachteten kurzen Civren, welche anscheinend individuell hier und da bei verschiedenen Enerinus-arten vorkommen kénnen.” There is a considerable difference, however, between a regular verticillate arrangement of cirri and their occasional presence here and there upon the stem, about which Beyrich does not speak very confidently, so far as Encrinus is concerned. I cannot make out, indeed, that any stem of an Encrinus has ever been described as bearing isolated cirri in the manner referred to by Beyrich ; while, on the other hand, the verticillate arrangement has been discovered by Picard* in an imperfectly preserved fragment from the Muschelkalk which he has described as Enerinus beyrichi—* Der Stengel ist von seinem untersten Theile an mit Ranken versehen. Dieselben treten von unten herauf erst spirlicher und in grésseren Abstiinden auf; am oberen Theile ist je das achte Siiulenglied ein Cirrentriger und erscheint horizontal etwas verdickt. Die Anhaftestelle fiir die Cirre befindet sich regelmiissig auf der concaven Fliche zwischen je zwei der finf Kanten, so dass em Wirtel von 5 Cirren den Stiel umgiebt.” He continues—“ Als Pentacrinus wage ich meinen Fund nicht auszusprechen. Denn obwohl die Fiille an Cirren und der ganze Habitus der Siiule sehr zu dieser Auffassung driingt, hat mich doch die Zusammensetzung der Krone, soweit sie klar ist, bestimmt, bei der Gattung Hucrinus zu bleiben.” There would seem therefore to be no doubt as to the oceurrence of cirrus-verticils on the stems of other Neocrinoids besides the Pentacrinidee ; while there are certain Palzocrinoids both in this country and in America which present the same character. Although, however, this fact diminishes the value of that peculiarity of the Pentacrinidee which is most evident at first sight, it does not follow that the verticillate arrangement of the cirri in these other types is also associated with the presence of syzygies at the nodes and the mode of union of the internodal joints, which are such especial features of all the Pentacrinidee. The Pentacrinus dubius of Goldfuss and Quenstedt shows these points very well, the five petals being visible on the faces of many joints found in the Muschel- kalk at different localities ; while the stem of von Schlotheim’s specimen (6 inches long) 1 Ueber die Krinoideen-Reste im Muschelkalk, Newes Jahrb. f. Mineralogie, Jahrg. 1837, p. 32, Taf. ii. 2 Crinoideen des Muschelkalks, loc. cit., p. 36. 3 Zeitschr. d. deutsch. geol. Gesellsch., Jahrg, 1883, p. 201. 296 THE VOYAGE OF H.M.S. CHALLENGER. terminates below in a nodal joint owing to its separation at the syzygy, as is the case with so many fossil as well as recent Pentacrimide. Although therefore it seems tolerably certain that cirrus-verticils may occur in some species of Hnerinus, the other characters of many of the stem-fragments from the Muschelkalk render it equally certain that Pentacrinus or an allied genus existed in the same seas as Encrinus. This has long been admitted in the case of the St. Cassian beds, which are considerably above the horizon of the Muschelkalk ; and they have yielded to Laube* five varieties of Penta- crinus-stems, which he has temporarily referred to as many species. Associated with these he found one calyx which appears to belong to Pentacrinus; but it was too imperfectly preserved for a definite opinion to be formed upon this point. All these earlier forms seem to belong to the section of the genus which was desig- nated “ Basaltiformes” by Quenstedt, after one of Miller’s species with a pentagonal stem. Essentially similar stems are found all through the remaining secondary rocks from the Lias upwards, in the Nummulitic Limestones of Biarritz and Kreissenberg, in the London Clay, and in the Italian Tertiaries. The calyces associated with them have a monocyclic base, and bear simple or dichotomous arms, the two limbs of each fork being of equal value, just as in the recent forms. Quenstedt’s other two groups, the Briariden and the Subangularen, are those to which the generic name Hxtracrinus was applied by the Messrs. Austin. The type is limited in Europe to the Lias and Lower Oolites. Htra- crinus briareus appears to occur in the lowest ‘ quick ledge” at Lyme Regis, which corresponds to Quenstedt’s lowest bed a; but the type does not reach into the Middle Lias, nor indeed into the upper beds of the Lower Lias. In the Jura, however, Hxtra- crinus briareus has not been found below the Marlstone (Lias y and 6); but it ranges up through the Posidonia-beds, and is said to occur in the Lower Oolites. The range of the Subangularen is more limited. They do not occur in the Lower Lias of either England or Germany, nor do they reach the top of the Posidonia-beds. Many varieties have been made of both species, especially by Quenstedt; but it is note- worthy that neither species occurs in all the three divisions of the Lias, Hxtracrinus briareus being limited to one only, at any rate in this country. Those who have recognised Eztracrinus as a genus, as, for example, Mr. R. Etheridge,’ F.R.S., have usually regarded it as limited to the Lias. The Messrs. Austin, however, speak of Haxtracrinus briareus as occurring in the Cornbrash at Kingscote Turn- pike. They are certainly wrong about the species, but I am very strongly inclined to believe that they are correct as regards the genus, and also that the occurrence of the Briariden in the Brown Jura (Inferior Oolite), as mentioned by Quenstedt,? is not unlikely. Die Fauna der Schichten von St. Cassian, Denkschr. d. k. Akad. d. Wiss. Wien., Bd. xx., xxiv., pp. 267-278. 1 2 See his Presidential Address to the Geological Society, Quart. Journ. Geol. Soc., 1882, p. 147 (of separate copy). 5 Eneriniden, p. 270. REPORT ON THE CRINOIDEA. 297 In the year 1876 a large Pentacrinus colony was discovered at Sennecey-le-Grand. Numerous very perfect individuals were obtained and carefully described by de Loriol.' He found a verticil of cirri on every joint, and described their faces as follows :-— “Ta surface articulaire est plane; les petales de la rosette articulaire sont fort étroits, et ont Tapparence de cinq petites rigoles aboutissant aux cinq angles du pentagone et limitées par deux petits bourrelets paralléles, plus élevés sur l'une des faces de l'article que sur l'autre, et couverts de tres fines crénélures.” The figure which he gives (pl. i. fig. 10) shows the complete correspondence of these joints with those of the Liassic Hxtracrinus ; and he found this correspondence ulso in the other characters of the type. The radials extend slightly downwards over the top stem-joints, and the characters of the arm-divisions are almost exactly as in Extracrinus, except that the main arms and the armlets which they bear are more equal in size than in the typical species. De Loriol identified this species with Pentacrinus dargniesi of Terquem and Jourdy, though he considered it as belonging to the same group as Hxtraerinus briareus; but he hesitated to adopt Austin’s genus, and he subsequently stated that there was no reason to do so.” He also pointed out that the characters of the stem-joints and cirri of Quenstedt’s two species Pentacrinus briareus zollerianus and Pentacrinus briareus achalmianus, both from the Brown Jura (Inferior Oolite), indicate their affinity to this group. In the same memoir he described and figured some other stem-joints presenting all the Extracrinus- characters from the same formation (Bajocien) of Langres, and he subsequently found both these types at corresponding herizons in Switzerland. Hereferred at the same time to the Pentacrinus nodotianus, VOrbigny, which was described by its founder as being “voisine du Pentacrinus briareus.” Very similar stem-joints, each bearing five cirri, and having crenulated linear petals, occur in the Coralline Oolite of various parts of Switzerland, and are described as Pentacrinus buchsgauensis by de Loriol, who notes their resemblance to those of Pentacrinus briareus as a point of special interest.” We may therefore, I think, consider it certain that Extracrinus extends up above the Lias into the Lower Jurassic rocks of the Continent, and the same is undoubtedly the case in England. The Great Oolite of Minchinhampton contains stem-joints with the same linear, crenulated petals as those of the Liassic Hxtracrinus briareus; while similar joints, together with arm-fragments showing the characteristic inequality of division, abound in the Forest Marble at Malmesbury. _ To the genus Extracrinus I would also refer the Pentacrinus asteriscus from the 1 Notice sur le Pentacrinus de Sennecey-le-Grand, p. 7. Both in this work and in the Swiss Crinoids this type is called Pentacrinus dargniesi by de Loriol. But the plates are lettered Pentacrinus chabasi, P. de Loriol. 2 Swiss Crinoids, p. 116. 3 Thid., pp. 153, 154. (ZOOL, CHALL, EXP,—PART Xxx1I,—1884.) Ti 38 298 THE VOYAGE OF H.M.S. CHALLENGER. American Jura-Trias (Jura only ?), which was first discovered by Meek and Hayden.’ It was subsequently found in Utah by Wheeler’s Survey, and owing to the constancy of its characters, even in examples collected at widely separate localities, it has been relied on with considerable confidence in the identification of Jurassic strata. According to Meek and Hayden there are five large, oval, petaloid areas, bounded on either side by “rather narrow, slightly elevated, transversely crenulated margins,”” and the figure which was published later by White’ clearly shows that the affinities of this species are with Hwtra- crinus rather than with Pentacrinus, of which it has been hitherto regarded as the only species yet recognised in the American Jurassic rocks. Hayden’s Survey found it in 1877 extending through a considerable thickness of Jurassic limestones in Idaho and Wyoming.* The supposed Triassic beds of Dun.Glen and the Pah Ute range contain a slightly larger form of joint, which differs from: the Jurassic specimens. It was found associated with what are regarded as unmistakable Triassic fossils and also a Spirifera. Mr. Emmons’ speaks of it as follows:—‘ It should he stated also that these disks of Penta- crinus found in the Dun Glen limestone vary somewhat from the type specimens, and are all of larger size, reaching one-fourth of an inch in diameter, while those of Jurassic age scarcely reach one-fifth of an inch. Prof. Whitfield suggests that the Dun Glen variety may possibly be a new species.” Elsewhere, too, it is stated by Hall and Whitfield® that this Triassic form from Dun Glen differs from the Jurassic specimens ‘in the more obtuse points of the star, and the filling up of the angles between the points, and also in the broader form of the elliptical figures on the articulating surfaces of the disks.” These are just the differences between the stem-joints of Hxtracrinus and those of Pentacrinus, as explained above ; and I am therefore disposed to think that this Triassic type with broader petals may be a true Pentacrinus, more especially as we have no knowledge of any European Extra- crinus below the Lias. It must be remembered that nearly all of these identifications are based upon the characters of the stem-fragments only, the calyx.and arm-bases being but rarely preserved. Every one who has examined moderately long pieces of stem, whether recent or fossil, has noted the variation of characters which they present in different parts; and there has therefore been a general disposition not to place too much reliance on species of which only the stems are known. I have been surprised to find, however, in the case of 1 Paleontology of the Upper Missouri, Invertebrates, part i. p. 67, pl. iii. fig. 2. * Proc. Acad. Nat. Sci. Philad., March 1858, p. 49. 3 Report upon Geographical and Geological Explorations and Surveys west of the One Hundredth Meridian, in charge of First Lieut. Geo. M. Wheeler, vol. iv. part i., Palzeontology, p. 162, pl. xiii. fig. 6,a. 4 Eleventh Annual Report of the U. S. Geological and Geographical Survey of the Territories, embracing Idaho and Wyoming, 1879, pp. 626, 627. 5 Report of the Fortieth Parallel Survey, Descriptive Geology, vol. ii. p. 711. 6 Thid., vol. iv. p. 280, pl. vi. fig. 16. REPORT ON THE CRINOIDEA. 299 recent types that when allowance is made for the different stages of growth, the characters of the stem are of much use in the distinction of species. This is especially the case if the number of internodal joints can be ascertained, which is not often possible, however, with fossil stems. But I am more disposed than I formerly was to accept the numerous species described by de Loriol and Quenstedt on the characters of the stem alone. Under these circumstances it is possible that more of the Continental species may eventually be found to occur in Britain, the number at present known being very small. The geological range of individual species, both of Pentacrinus and of Extracrinus, seems to be rather limited, no species occurring in all three divisions of the Lias. Out of fifteen species of Pentacrinus which are found in the Middle and Upper Lias of Britain, only two are common to the two horizons. Neither of the two Lower Lias species reach the Middle Lias, though Pentacrinus basaltiformis dogs so on the Continent. This and Pentacrinus psilonoti axe the only Continental species which have yet been recognised in the British Lias. One species of the Kimmeridge Clay, Pentacrinus sigmaringeisis, also oceurs in the White Jura of the Continent. This agrees very well with the geographical distribution of the Pentacrinide in the recent seas, the four West Indian species, though abundant in the Caribbean Sea, not occurring elsewhere ; while the remaining two Atlantic species have respectively been found at one and at three stations only. Pentacrinus naresianus was obtained in the West Pacific in lat. 29° 55’ S., and also in lat. 4° 33’ N. (or possibly 9° 26’ N.), and has the widest geographical range of any Pentacrinus, recent or fossil, that I am aequainted with. Like the Silurian Crinoids, therefore, the species of Pentacrinus, both recent and fossil, seem to be somewhat limited in their geographical range. The genus has, however, a wider geographical range than Metacrinus, which is confined to the Pacifie Ocean and the East Indian Archipelago. On the other hand, while fourteen species of Metacrinus are known, Pentacrinus is only represented by eight, together with the doubtful form which I have called Pentacrinus (?) mollis (Pl. XXXIT. figs. 7-10). The mutual relationships of these eight species are shown in the followmmg table; and it will be seen that they fall into two very natural groups, which have the four Caribbean and the two Pacific species equally divided between them. 300 THE VOYAGE OF H.M.S. CHALLENGER. Genus Pentacrinus, Miller. f \ { Usually fifteen to eighteen inter- ] nodal joints. The hypozygal does not share in the cirrus- sockets. Generally more than | 1 three joints between the _ irre- f : asterius, Linn. 7 Cirri large and | | creas 2 ised pre one Pinnule Sipe joints have forwar ee Raye sas processes, HA NG Six to eight internodal joints. The The two} times. h eee sya fon engeea| ) iuve ypozygal shares in the eirrus- Bog. as and | Citi at sockets. Only two or three joints | 2. muilleri, Oersted. ri first | each between the. regular arm-divi- ane de. L sions. J two joints J oe ee cat | | Fifteen =i aA twenty - five “ath peat cirrus-joints. ’ pote a YS Rays only | One or two internodal joints, . 93. maclearanus, Wyv. Thoms. { . divide three | ieee ae to forty-five intermodal \ 4, wyville-thomsont, Jefireys. two joints united by L syzygy. Two ‘and three cirri alternately at successive nodes. Rays | divide three times ; each division-of two joints united by 7 5.. alternicirrus, n. sp. | syzygy. Four internodal joints. { Ten armsonly. The third brachial a. syzygy with angular syzygial faces. First pinnule on the second brachial. $ 6. naresianus, N. sp. Eight to seventeen internodal joints. The two outer rad- { Five to seven internodal joints. } ials and | Nodal joints not enlarged, and | the _ first the hypozygal sharing but little $ 7. dlakez, n. sp. beyond) Rays may divide three | it the cirussockets. Syzygial : times. The second ea them uni- : ted by bi- a ee ae Te Eleven or twelve internodal joints. ) fascial arti- | brachial: P Nodal joints enlarged and pro- | culations. Jecting, and the hypozygal 8. decorus, Wyv. Thoms grooved to receive the cirrus- ; : , ; bases. Syzygial faces nearly | [ {| plane. J 1. Pentacrinus asterius, Linn., sp. (PL X13 PES wies. 915=95>) Seika Pl. XVII. figs. 7, 8). 1761. Palmier marin, Guettard, Mémoires de Mathématique et de Physique tirés des Registres de l’Academie Royale des Sciences, de l'année MDCCLYV., Paris, 1761, p. 225. 1762. Encrinus, capite stelluto, ramoso dichotomo. Stipite pentagono-equisetiformi., Ellis, Phil. Trans., vol. lii. pt. i. for the year 1761, London, 1762, p. 358. 1766. Isis asteria, Linneus, Systema Nature, ed. xii., Holmie, 1766, t. i. p. 1288. REPORT ON THE CRINOIDEA. 301 1775. Isis asterias, Miiller, Linne’s Natursystem, nach der zwolften lateinischen Ausgabe, N iirmberg, 1775, Bad. ii. p. 742. 1788. Isis asteria, Linneus, Systema Nature, ed. xiii., cura, J. F. Gmelin, Lipsix, 1788, t. i, pars vi. p. 3794. 1816. Encrinus caput-Meduse, Lamarck, Histoire Naturelle des Animaux sans Vertebres, t. ii., Paris, 1816, p. 435. 1820. Pentacrinites vulgaris, von Schlotheim, Die Petrefactenkunde, Gotha, 1820, p. 327. 1821. Pentacrinus Caput-Meduse, Miller (pars), A Natural History of the Crinoidea, Bristol, 1821, p. 48, pl. i. 1834. Encrinus caput-Meduse, de Blainville, Manuel d’Actinologie, Paris, 1834, p, 254. 1836. Pentacrinus Caput-Meduse, Buckland, Geology and Mineralogy, London, 1836, p. 432, pl. 52, fig. 1. 1843. Pentacrinus caput-Meduse, Miiller (pars), Abhandl. d. k. Akad. d. Wiss. Berlin, Jahrg. 1841, Pa oolatels 1845. Pentacrinus Caput-Meduse, Austin® (pars), A Monograph on Recent and Fossil Crinoidea, Bristol, 1843-45, p. 111, pl. 14. 1856. Pentacrinus caput-Meduse, Oersted, Forhandl. Skand. Naturf., 7°" Mode i Christiania, 1856, p. 202. 1862. Pentacrinus caput-Meduse, Dujardin and Hupé, Hist. Nat. des Zoophytes, Kchinodermes, Paris, 1862, p. 181. 1864. Cenocrinus Caput-Meduse, Wyville Thomson, The Intellectual’ Observer, August 1864, p. 3. 1864. Pentacrinus asteria, Liitken, Vidensk. Meddel. f. d. nat. Foren.-i Kjgbenhavn, 1864, p. 207. 1865. Pentacrinus (Neocrinus) asterias, Wyville Thomson, Phil. Trans., vol. clv., 1865, p. 542. 1872. Pentacrinus asteria, Wyville Thomson, Proc. Roy. Soc. Edin., vol. vii. p. 765; and The Depths of the Sea, p. 435. 1877. Pentacrinus asteria, Wyville Thomson, The Atlantic, London, 1877, vol. ii. pp. 123-126. 1882. Pentacrinus asteria, P. H. Carpenter, Bull. Mus. Comp. Zodl., vol. x. p, 168. Dimensions. Length of stem to twentieth node, : : : ; . 48 cm. Greatest diameter of stem, ; : ; ; 5 ; 7 mm. Longest cirrus (fifty joints), : 5 ‘ : : cls Diameter of calyx across first radials, . c : . ally 53 Diameter of disk, Z 3 A z : : A ealiten ys Length of arm (one hundred joints), 5 : é 2 LOOT; Length of distichal pinnule (twenty-five joints), 5 te a Sie: Length of first pinnule after tertiary axillary (thirteen joints), . Fe ae Panes Stem long, robust, and generally smooth. Outline pentagonal, with slightly rounded angles, but more circular in the lower part. Internodal joints thirteen to twenty-one (usually fifteen to eighteen) in number, with but slightly crenulated edges even in the upper part of the stem. Nodal joints marked by large, transversely oval cirrus-sockets, which occupy almost their whole height. The sockets have sharp, well defined rims, and are entirely filled by the articular facets. Cirri composed of thirty-five to fifty stout, smooth, and tolerably equal joints, with a small terminal claw and no opposing spine ; though the ventral surface of the later joints is often marked by two or three blunt points. Infra-nodal joints rarely grooved to receive the cirrus-bases, and then but slightly so. Lowest limit of the interarticular pores between the ninth and twelfth nodes. 1 The Messrs. Austin and also Dujardin and Hupé give an undated reference to Parra’s Hist. Nat. Havanne p- 191, pl. 70, in which this type seems to have been mentioned by the name Palma animal. But I have been unable to consult the work, and can therefore do no more than make this reference to it. 302 THE VOYAGE OF H.M.S. CHALLENGER. Basals triangular or rhomboidal, not meeting laterally on the exterior of the calyx. The two outer radials united by syzygy. The grouping of the ray-divisions and the number of their component joints are somewhat irregular. Primary arms of two to six (usually three or four) distichal joints; secondaries of two to eighteen (usually seven to nine) palmar joints ; tertiaries of six to fourteen joints, and occasionally another division after eight or ten joints more. The tertiary arms which divide are often only the two outer ones in each group of four, so that the distichal axillary bears six arms, viz., 2,1; 1,2; but there are sometimes “more than a hundred arms.”* The first two joints beyond each axillary united by syzygy, with a pinnule on the epizygal. No other syzygies on the arms, which consist of about a hundred smooth, oblong joints, the outermost ones overlapping slightly, Distichal and palmar pinnules very large and stout, with thick lower joints, those of the later arm-divisions and of the free arms being much smaller. The joints of these large lower pinnules have the distal edge raised into a strongly marked keel which projects forward over the base of the next joint; and this feature recurs on all the pinnules of the arms, though it is less distinct in their middle and outer portions. The perisome uniting the rays up to the level of the distichal axillaries is paved by large, closely set plates. Similar plates cover the ventral surface of the disk and arm- bases. Arm-groove moderately wide, and protected by numerous irregular plates. Pinnule-ambulacra have covering plates, but no definite side plates, Colour in spirit or dry, a light yellowish-brown. Localities.—Various parts of the Caribbean Sea—Nevis, Martinique, Barbados, Guadeloupe (Dr. Schramm) ; off Saba Island, 320 fathoms (Captain Cole). This species was only once dredged by the U. 8S. Coast Survey steamer “Blake,” cruise of 1878-79, No. 157, off Montserrat, 120 fathoms. Remarks.—The specific name caput-Meduse, which was originally bestowed by Lamarck on the West Indian Pentacrinus described by Guettard, was used by Miller, Goldfuss, Miiller, and all later writers till the year 1864. In August of this year the late Sir Wyville Thomson? published a popular article on Sea Lilies, in which he ex- pressed the opinion that the fossil Pentacrinus briareus, a widely different species from the recent Pentacrinus caput-Meduse, “seems, however, to have a just claim to be recognised as the type of the genus Pentacrinus;” and he therefore proposed to give the generic name Cenocrinus to the West Indian species, for which he retained the original title Caput-Meduse. Liitken,’ however, reverted to the original specific designation employed by Linneeus,* and called the type Pentacrinus asteria. In the following year* Thomson referred to it as Pentacrinus (Neocrinus) asterias, Linn.; but he subsequently*® gave up 1 See Wyville Thomson, The Intellectual Observer, August 1864, p. 5. 2 The Intellectual Observer, August 1864, p. 3. 5 Om Vestindiens Pentacriner, loc. cit., p. 207. * Systema Nature, ed. xii., Holmiz, 1766, t. i. p. 1288. 5 Phil. Trans., 1865, p. 542. ® Proc. Roy. Soc. Edin., vol. vii., 1872, p. 765; and also The Depths of the Sea, p. 435. REPORT ON THE CRINOIDEA. 303 both the generic names Cenocrinus and Neocrinus and described the type as Pentacrinus asteria, Linn., as Liitken had previously done. It was clearly right to return to the specific name employed by Linnzeus, although he was utterly at fault as regards the generic position of the type. But every writer on the subject, myself included, has used a wrong termination to the specific name. Linnzeus wrote Isis asteria, which appears as Isis asterias in Miiller’s edition of the Systema Nature (Bd. ii. p. 742), published at Nuremberg in 1775; and this has been quoted by de Blainville and others. But when the species came to be referred to Pentacrinus, and the Linnean specific name was restored. in place of caput-Meduse, it should have been written Pentacrinus asterius, the expression Pentacrinus asteria, used by Liitken, Thom- son, and myself being a false concord ; for it is evident that the etymology of Linnzeus’s name Isis asteria is the adjective dorépios, starry, and not the noun Asteria, cat’s eye. I am indebted for this tardy correction to the critical acumen of my friend Prof. F. Jeffrey Bell. But as it did not reach me till all the plates illustrating the type and most of the morphological section of the Report’ had been printed off, I have been unable to avail myself of it as fully as I should like to have done. It is somewhat curious that this species, which for the greater part of a century was the only known living representative of the genus, should be comparatively so little known at the present time. But one specimen of it was ever dredged by the ‘“ Blake,” whereas Pentacrinus decorus was obtained by the hundred ;: and even stem-fragments were very rarely met with, One specimen was taken by Captain Cole of the telegraph steamer “ Investigator,” in 320 fathoms off Saba Island ; and it is now in the zoological collection of the Natural History Museum. The agents of Mr. Damon of Weymouth have been successful in procuring several excellent specimens, which have been bought by different museums, but I have not been able to examine more than a very few of them. The preceding description is based upon the characters presented by the following examples of the type :—A. Miller's original specimen from Nevis, now in the geological department of the Natural History Museum. B. One dry specimen and two others in spirit, all in the zoological department of the same museum. C. One dry specimen in the Hunterian collection of the Royal College of Surgeons. D. Two dry specimens obtained by Dr. Carpenter and Sir Wyville Thomson from Mr. Damon of Weymouth. I have not made a personal inspection of Guettard’s original specimen, but when Mr. Perey Sladen was in Paris for the purpose of investigating the collection of Asterids in the museum, he was permitted by Prof. Perrier to examine it on my behalf; and from the notes of its characters which he was kind enough to give me, together with the original figures of Guettard, I have no doubt that it is a fairly normal specimen of the type. Pentacrinus asterius is much more robust than any of the other recent species of the genus, none of which have such wide stem-joints, though these are not so large as in some fossil species. The stem also seems to grow to a greater length than that of any other recent 304 THE VOYAGE OF H.M.S. CHALLENGER. type but the slender Pentacrinus decorus. But as in so many other species it was liable to fracture just below a node, so that the individual led a semi-independent existence; for I have one stem-fragment in which the lowest joint is decidedly worn aud its central canal closed up by a small round boss which projects above the remaining surface of the joint. The length of the internodes in Pentacrinus asterius distinguishes it at once from Pentacrinus miilleri, its nearest ally, which has similar long and stout cirri; while the infra-nodal joint is usually somewhat grooved to receive the eirrus-bases. This is but rarely the case in Pentacrinus asterius, and then only to the slightest possible extent, so that the cirrus-socket is practically limited to the articular facet, without any extension either upwards or downwards. The stem of Pentacrinus asterius is thus very readily identified, and the same may be said of the arms, which is rarely the case with the other species of the genus, unless the ventral groove be examined. For the peculiar features of the pinnules are very characteristic. They are well shown in Miller's figure’ and likewise in those given by Miiller,? who specially referred to the projections from the ends of the pinnule-joints. The great thickness of the basal joints in the distichal and palmar pinnules, especially the former, is a somewhat unusual character in a Pentacrinus. A trace of it may be seen in some forms of Pentacrinus miilleri ; but in most species of the genus the lower joints of the first pinnules are laterally compressed, and lie close against the arm. They thus present a great contrast to the almost cubical or prismatic basal joints of the first pinnules in Metacrinus (Pl. XLIII. figs. 2, 4). The preceding description differs in one important respect from those given by Miiller and Liitken. The former author spoke of the union between the second and third radials as an articulation, but was somewhat obscure about its nature. He was not able to separate the two joints, but seems to have inferred that they were united by a bifascial articulation such as he found in Antedon rosacea.’ While, however, he stated expressly that the latter type has no muscles between the second and axillary radials, he described and figured muscles as existing in this position in Pentacrinus caput-Meduse.* This led Liitken to state® that the existence of an articulation between the two outer radials of Pentacrinus asterius was an important character separating it from Pentacrinus miilleri, which has these joints united by syzygy. Neither he nor Miiller, however, had ever actually separated the joints, specimens being then too valuable, or the real state of the case would have become evident at once. This was first discovered by Sir Wyville Thomson,° who pointed out that there is really a syzygy between the two outer radials of Pentacrinus asterius. In this respect, therefore, this species resembles Pentacrinus miilleri, instead of differing from it as was supposed by Liitken. But unfortunately Sir Wyville totally misconceived the real character of Oersted’s species, and confounded it with the one previously described by } Op. cit., p. 51, pl. ii. fig. 5. ? Bau des Pentacrinus, p. 48, Taf. ii., iii. % Ibid., p. 26, Taf. ii. fig. 12. 4 Ind., p. 30, Taf. ii. fig. 8. ° Om Vestindiens Pentacriner, loc. cit, p. 202. ® Proc. Roy. Soc. Edin., vol. vii., 1872, p. 766. REPORT ON THE CRINOIDEA. 305 himself under the name of Pentacrinus decorus. He was thus led to state that while the two outer radials of Pentacrinus asterius are united by syzygy, those of Pentacrinus miilleri are articulated, a mistake almost the opposite of that made by Liitken. It is not difficult to understand how Miiller’s error arose ; for the line of syzygy is not dotted as it is in the Comatul, where the apposed faces are marked by radiating ridges. There is little or nothing of this striation on the syzygial surface of Pentacrinus asterius (Pl. XII. figs. 18, 21); and the muscular unions of the remaining calyx- and arm-joints are so very _close that there is hardly any external character by which the syzygy between the two outer radials may be detected. Its presence is evident enough between the two joints following each axillary, as they are shorter than their successors. But nothing of this kind appears in the case of the radials, and as they are very apt to become shghtly separated at the edges I have found it almost impossible, especially in dry specimens, to determine the real nature of the union without separating the joints. This was done by Sir Wyville Thomson, whose preparations are figured in Pl. XI. figs. 15-25. The basals of Pentacrinus asterius are of very variable size, like those of Pentacrinus decorus, though not to the same extent. They are sometimes small, rounded knobs, not meeting one another upon the exterior of the calyx; or larger and more prominent, meeting their fellows in the re-entering angles beneath the radials ; but they never form a completely closed ring of triangular or pentagonal plates flush with the radials, as they do in Pentacrinus wyville-thomsoni, Pentacrinus alternicirrus, and some other species (Pl. XVIII. figs. 1-3; Pl. XIX. figs. 1, 6,7; Pl. XX. figs. 2, 3; PI. DEX): Liitken, Thomson, and others have endeavoured to establish as one of the characters of Pentacrinus asterius that the nodal joints of the stem are low and simple, while those of Pentacrinus miilleri and Pentacrinus decorus are thick and double, consisting of two parts united by syzygy. This is not really the case, however. In all recent Pentacrinidee the nodal joints proper, @.e., those which are pierced by the canals lodging the cirrus- vessels, are always single and united by syzygy to those next below them. But the line of junction is sometimes so nearly obliterated as to be only visible with difficulty ; while in other cases, such as Pentacrinus asterius (Pl. XIU. fig. 8), it is hardly distinguishable from the ordinary junction lines between the internodal joints, which are crenulated much less than usual. The following may therefore be regarded as the special marks of Pentacrinus asterius:— a robust stem with long internodes and wide cirrus-sockets; the ray-divisions rather irregular in number and grouping ; the projections of the pinnule-joints. Little is known about the range of Pentacrinus asterivs, either in depth or in space. Examples have been obtained off Barbados, Guadeloupe, Martinique, Montserrat, Nevis, and Saba Island; while the only two cases in which the depth is known with certainty are respectively 120 and 320 fathoms. Like the three other West Indian species, it is not known to occur out of the Caribbean Sea. (4oOL. CHALL. EXP,—PART XXXII, —1884.) 39 306 THE VOYAGE OF H.M.S. CHALLENGER. 2. Pentacrinus miilleri, Oersted, 1856 (Pls. XIV., XV.; Pl. XVII. figs. 9, 10). 1821. Pentacrinus caput-Medusce, Miller (pars), A Natural History of the Crinoidea, p. 46. 1843. Pentacrinus caput-Meduse, Miiller (pars), Abhandl. d. k. Akad. d. Wiss. Berlin, 1843, p. 185. 1845. Pentacrinus Caput-Meduse, Austin (pars), A Monograph of Recent and Fossil Crinoidea, p. 111. 1856. Pentacrinus Miilleri, Oersted, Forhandl. Skand. Naturf., 7° Mode i Christiania, 1856, p. 202. 1864, Pentacrinus Milleri, Liitken, Vidensk. Meddel. f. d. nat. Foren. i Kjgbenhavn, 1864, Nr. 13-16, p. 207. 1865. Pentacrinus (Neocrinus) Miilleri, Wyville Thomson, Phil. Trans., 1865, vol. clv. p. 542. 1882. Pentacrinus miilleri, P. H. Carpenter, Bull. Mus. Comp. Zodl., vol. x., No. 4, p. 170. non Pentacrinus Miilleri, Wyville Thomson, in Proc. Roy. Soe. Edin, vol. vii. p. 776; and in The Depths of the Sea, p. 442. non Pentacrinus Miilleri, Agassiz and Pourtalés, in Bull. Mus. Comp. Zodl., vols. v., vi. Dimensions. Total length of largest specimen,1 : E . . o2cm. Greatest length of entire stem, rounded off at sixbeaith nue, : ; . 185 mm. Shortest stem, rounded off at twelfth node, : : : : eels fi re Diameter of stem, 5 . : ; : : c 6°, Longest cirrus (forty-three joints); C 2 : : ; E ivionr. Diameter of calyx, ; : ; : , ; 3 elle Diameter of disk, 5 5 : : : ; : 14 ,, Length of arm (one hundred romtey : : : 5 IMU op Length of pinnule on first free brachial (fifteen seni) : ; : Sepa thsh Ao Length of pinnule from middle of arm (twenty-one joints), . - ORS, Stem robust, but of no great length. Outline pentagonal, with rounded angles and smooth surface. Internodal joints four to eleven (usually six to eight) in number, with but slightly crenulated edges, even in the upper part of the stem. Cirrus-sockets trans- versely oval and not reaching the upper edges of the nodal joints, but extending more or less downwards on to the infra-nodals, which are grooved to receive the cirrus-bases. Cirri composed of thirty to forty-five stout, smooth, and tolerably equal joints, the later ones of which may have a couple of small, blunt projections on the ventral side. Terminal claw small and without an opposing spine. Lowest limit of the interarticular pores between the fourth and eighth nodes. Basals variable ; sometimes pentagonal, forming a closed ring ; or rhomboidal, barely in contact by their lower angles; and sometimes quite small, not meeting at all upon the exterior of the calyx. Rays and their subdivisions not separated by perisome, but in close lateral contact, the joints as far as ‘the lowest free brachials beyond the tertiary axillaries having their sides more or less flattened, often very much so. The two outer radials united by syzygy. There are usually six or eight arms on sometimes triangular 1 The total length of this individual, which was obtained by Captain Cole, and is now in the Natural History Museum, is slightly greater than that of the largest specimen dredged by the “ Blake.” The stem, which is 19 em. long, is broken just below the twenty-first node. But in the same bottle there is a fragment which appears to be the bottom part of this stem, and has the lowest nodal joint closed in the usual way. _a\ REPORT ON THE CRINOIDEA. 307 each ray in the following order—2,1; 1,2; or 2,1,1;1,1,2, the axillaries being limited to the outer arm of each successive pair. Primary arms of one to three (usually two) distichal joints, which are united by syzygy. Secondary arms of two to seven palmar joints, usually three. There may be one, or more rarely two, further divisions, which are usually of three joints each, but may have five or six. The first two joints after each axillary are united by syzygy, the epizygal, when not itself an axillary, bearing the first pinnule. No other syzygies on the arms, which consist of about one hundred smooth, oblong joints, the lowest of which have flattened sides, and are sometimes more or less tubercular, while the outer ones overlap slightly. The first pinnules are somewhat longer and stouter than the following ones, after which the size again increases. The pinnules have a smooth, sharp dorsal edge, and are generally composed of flattened joints, the lowest of which are slightly wider than their successors, and are sometimes markedly prismatic. The disk bears numerous scattered calcareous granules, but no regular pavement of plates, and there is no plated perisome between the rays. Arm-groove moderately wide, and closely covered by numerous, small, irregular plates. Pinnule-ambulacra have covering plates and ill defined side plates. Colour in spirit, white or brownish-white, somewhat darker on the pinnules. Localities.—Guadeloupe, St. Croix, St. Thomas, Barbados; between Saba and Eustatius Islands, 531 fathoms (Captain Cole). The dredgings of the U.S. Coast Survey steamer “ Blake,” cruise of 1877-78, off Havana; 175 fathoms. Cruise of 1878-79. No. 100, off Morro Light ; 250 to 400 fathoms. No. 101, off Morro Light; 175 to 200 fathoms. No. 157, off Montserrat; 120 fathoms. No. 171, off Guadeloupe ; 183 fathoms; bottom temperature, 553° F. No. 193, off Martinique ; 169 fathoms; fine sand, dark mud, and shells; bottom temperature, 51°F. No. 218, off St. Lucia; 164 fathoms; bottom temperature, 56°F. No. 269, off St. Vincent; 124 fathoms ; bottom temperature, 574° F. No. 274, off Barbados; 209 fathoms: fine sand and ooze; bottom temperature, 534° F. No. 280, off St. Charles Lighthouse, Barbados ; 221 fathoms; Globigerina sand; bottom temperature, 503° F. No. 283, off Barbados; 237 fathoms ; hard bottom; bottom temperature, 49°F. No. 291, off Barbados; 200 fathoms ; flat calcareous stones; bottom temperature, 492°F. No. 295, off Barbados; 180 fathoms ; hard bottom ; bottom temperature, 502° F. No. 296, off Barbados; hard bottom ; 84 fathoms; bottom temperature, 614° F. No. V. (Bartlett), Santiago de Cuba ; 288 fathoms. Remarks.—This species was discovered by the Danish naturalist Oersted, who brought an example to Europe from the Danish possessions in the West Indies. It was exhibited in the year 1856 at the meeting of Scandinavian naturalists in Christiania,’ and a brief 1 Forhandl. Skand. Naturf., 74 Méde i Christiania, 1856, p. 202. 308 THE VOYAGE OF H.M.S. CHALLENGER. preliminary diagnosis of it, together with a similar notice of Pentacrinus caput-Meduse (aster’us), was published in the report of the meeting. Such was the rarity of these Crinoids that Oersted’s discovery of a new species attracted but little attention, although an example of it from Guadeloupe had long been contained in the collection of the Geological Society of London, and had been referred by Miiller to Pentacrinus caput- Meduse. These facts seem to have escaped the notice of Sir Wyville Thomson, who himself described a new species (Pentacrinus decorus) in 1864, and spoke of it and Penta- crinus caput-Meduse as the only two known living species of the Stalked Crinoids.! Early in the next year, however, an elaborate memoir on the West Indian Pentacrinidze was published by Dr. Liitken, which has served as the basis of most of the subsequent work on the genus. Not only did he make a careful examination of Oersted’s original specimen of Pentacrinus miilleri, but he found that two other individuals in the Copenhagen Museum were identical with it; he was thus able both to discover some more important points of difference between Pentacrinus miilleri and the Linnean type, and also to work out some of the individual variations in the characters of Pentacrinus miilleri as defined by Oersted. In his preliminary diagnoses of Pentacrinus asterius and Pentacrinus miilleri, Oersted had already indicated the differences in the numbers of joints composing the arm-divisions of the two species. This character was still further investigated by Liitken,? who pointed out its influence upon the external appearance of the animal. Relying chiefly upon the figures of Pentacrinus asterius which were given by Miller and Miiller, he showed that the numbers of joints in the successive arm-divisions were respectively 5 or 6, 9 or 10, and 12. In Pentacrinus miilleri, on the other hand, these numbers are Di 2-4; 3; and 3-5; and it is almost always only the two outer arms on the ray which divide at all, so that the arms of any ray with secondary axillaries would be represented by the expression 2,1; 1,2; and by 2,1,1; 1,1,2, if tertiary axillaries be present. This is a sort of indication of the inequality of the arm-divisions of Extra- crinus, and is tolerably constant in Pentacrinus miilleri, though not limited to that species, for it is visible in Pentacrinus asterius, as detected by Quenstedt* in Miller’s fioure. After the publication of Liitken’s Memoir, Pentacrinus miilleri, Oersted, came to be recognised as a type distinct from the old Pentacrinus asterius. It was referred to by Sir Wyville Thomson,* together with -Pentacrinus asterius and Pentacrinus decorus, so that he evidently regarded it as distinct from both of them. Later on, however, he seems to have come to the conclusion that his Pentacrinus decorus was identical with Oersted’s species. For having previously said that Pentacrinus asterius and Pentacrinus decorus were the only two known living species of the genus, he made nearly the same 1 Sea Lilies, The Intellectual Observer, August 1864, p. 1. 2 Om Vestindiens Pentacriner, loc. cit., p. 203. * Encriniden, p. 190, Tab. 97, fig. 3. 4 Phil. Trans., vol. clv., 1865, p. 542. i. REPORT ON THE CRINOIDEA. 309 statement concerning Pentacrinus asterius and Pentacrinus miilleri.1 He likewise repeated most of his original description of Pentacrinus decorus as a diagnosis of Penta- crinus miilleri, with a reference under the latter name to the specimen which he had before him when describing Pentacrinus decorus. He stated that the two outer radials of Pentacrinus asterius were united by syzygy, and further added that “the arrange- ment of the joints and the syzygies in the eup is the same in Pentacrinus miilleri as ini Pentacrinus asteria, only the syzygy between the second radial and the radial axillary is not so complete.” This passage obviously refers to a ligamentous articulation as distin- guished from a true syzygy on the one hand, and from a muscular joint on the other ; and it is by no means in accordanee with Liitken’s very positive statements as to the presence of a true syzygy between the two outer radials of Pentacrinus miilleri. Neither does Sir Wyville’s deseription of the nodes as occurring about every twelfth joint agree with Liitken’s diagnosis, which records only four to ten internodal joints in Pentacrinus miillert. As a matter of fact there are eleven or twelve internodal joints in Pentacrinus decorus, and there is no syzygy at all between the two outer radials, but only a bifascial articulation such as occurs in the majority of the Neocrinoidea, and has often been wrongly spoken of as a syzygy, though clearly distinguished from it by Miller. This is shown in figs. 3 and 6 on Pl. XXXIV., a copy of which was lettered “ Pentacrinus miilleri, Oersted,” by Sir Wyville Thomson. I cannot but think, however, that if he had lived to work out the “ Blake” collection more fully than he was able to do before his health gave way, he would have retaimed his original views as to the distinctness of his Pentacrinus decorus from Pentacrinus miilleri, Oersted. The result of this confusion was that the numerous specimens of Pentacrinus decorus which were dredged by the “ Bibb” and the “Blake” in the Gulf Stream and in the Caribbean Sea were referred to Pentacrinus miillert by Pourtaleés and Agassiz.” The two species have really no sort of resemblance to one another, differing in all the characters of the stem, the cirri, the calyx, and the arms. The foregoing description is based upon an examination of ‘four specimens from the “Blake” collection, two purchased by Sir Wyville Thomson from Mr. Damon, one in the collection of Sir Rawson Rawson, and lastly that in the Museum of the Geological Society of London, which is mentioned by both Miller and Miiller as Pentacrinus caput- Meduse. Pentacrinus miilleri is readily distinguished from Pentacrinus asterius, which is its nearest ally, by the shortness of the internodes and the modification of the hypozygal joints, which, however, is far less marked than im Pentacrinus decorus. The basals generally form a complete ring ; while the branching of the arms is much more regular 1 Proce. Roy. Soc. Edin., vol. vii. p. 766; and The Depths of the Sea, pp. 484, 435; see also The Atlantic, vol. ii, p. 126. 2 Bull. Mus. Comp. Zool, vol. i. p. 357 ; Ibid., vol. v. pp. 56 and 214; Ibid., vol. vi. p. 296. 310 THE VOYAGE OF H.M.S. CHALLENGER. than in Pentacrinus asterius. There are fewer joints between the successive axillaries, and the characters of the pinnules are altogether different. In these latter points Penta- crinus miilleri closely resembles Pentacrinus maclearanus (Pl. XVL.), Pentacrinus wyville-thomsoni (Pl. XVIII. fig. 1), and Pentacrinus alternicirrus (Pl. XXV.). But the first named has only one or two internodal joints in the stem, while Pentacrinus wyville-thomsoni has from thirty to forty-five, so that they are both readily distinguish- able from Pentacrinus miilleri; while the grouping of the cirri on the stem of Pentacrinus altermcirrus is sufficient to distinguish this species at once. So far as I can judge from the material at my disposal, Pentacrinus miilleri is certainly the most variable of the Pentacrinide with the exception of Pentacrinus decorus. The stem does not seem to reach the length which it attains both in the latter species and in Pentacrinus asterius. In one instance it is rounded off at the twelfth node, only 135 mm. from the calyx, and Rhizopods are attached to the under surface of the lowest nodal joint. Another stem tapers gradually downwards from a width of 5 mm. at the calyx to 3 mm. at the sixteenth node, where it is rounded off 185 mm. from the calyx. The length of the internodes varies a good deal in different individuals, though as a rule it is tolerably constant in any given stem. The component joints are usually thick and thin alternately. This is very marked in the specimen represented in Pl. XIV., though not well shown in the figure; while in other cases the joints are more equal in height, as shown in Pl. XV. fig. 4. This figure should be compared with the correspond- ing one of Pentacrinus asterius (Pl. XIII. fig. 8), in which the cirrus-sockets are not so deeply hollowed as they are in Pentacrinus miilleri. Their shape, too, is somewhat variable in the latter type. In some stems (Pl. XV. fig. 4) they are transversely oval as in Pentacrinus asterius (Pl. XIII. figs. 4, 8), though not reaching so near the top of the nodal joint. But they always extend slightly downwards on to the hypozygal, which is not the case in that species. In other examples, however, the hypozygal is deeply grooved to receive the bases of the cirri, and the sockets thus become more circular in form ; so that it appears as if the cirri were borne conjointly by the two syzygial joints. This has been described as an important difference between Pentacrinus miilleri and Pentacrinus asterius, but erroneously so; for the whole of the articular surface is always on the nodal joint, which is the only one pierced by the canals lodging the cirrus-vessels. The cirri, though always stout, are considerably shorter in some forms than they are in others; and while some of them have quite smooth terminal joints, those of other individuals bear small blunt processes which never, however, reach to the size of a spine. The “Blake” collection includes a curious fragment of a stem which had broken between a nodal joint and the first joint of the internode above it. The upper part of _ the stem and the calyx are missing; but six irregularly shaped joints have been added above the node. One would like to know whether this reparation would ever have resulted in the formation of a new calyx and arms. Such an extensive reparation Cem REPORT ON THE CRINOIDEA. 311 seems scarcely possible, though the development of a new visceral mass inside the calyx iS not uncommon. As in Pentacrinus asterius, there is a considerable variation in the development of the basals. In the Copenhagen specimens described by Liitken, and in some of those which I have examined, they are pentagonal in outline and form a closed ring separating the radials from the top stem-joint. In other forms they are more prominent and rhomboidal or triangular in shape, but only just meeting one another in the re-entering angles of the calyx (Pl. XIV.; Pl. XV. fig. 2); while in Sir Rawson Rawson’s specimen they are small and inconspicuous (Pl. XV. fig. 1), as in some varieties of Pentacrinus decorus (Pl. XXXVI). The number of arms may vary from thirty-five to forty-five, some individuals occa- sionally having ten arms to the ray. Generally, though not invariably, the axillaries are limited to the outer arm of each pair in the manner already described; but I have not seen any individual in which the six- or eight-armed arrangement is constant on every ray. As there are very few joints separating the axillaries, there is comparatively little room for the arms, the bases of which are therefore more or less flattened laterally, both in the outer and in the inner parts of the rays. In fact, wherever an axillary occurs the ~ two arms which it bears have their inner faces flattened, while the outer sides of the rays are flattened continuously from the second radials to as far as some six or eight joints beyond the fifth axillary. This feature is especially marked in two fine specimens from the “ Blake” collection, which are also distinguished by the shape of their lower pinnule-joints. One is from Martinique and the other from Barbados. The calyx and arm of the former are repre- sented on Pl. XV. figs. 2, 3. The outer edges of the joints from the second radial onward are produced somewhat sharply upwards, and fit closely against those of adjacent joints. This is less prominent in the Barbados specimen, which shows an occasional tendency towards carination of the arm-bases. The other form is remarkable for the abnormal condition of one of its rays, as shown in Pl. XV. fig, 2. The third radial is articulated to the second instead of being united to it by syzygy. But it is itself a syzygial joint; so that there are primitively four radials, a character which indicates a tendency to variation in the direction of Metacrinus with its five or eight primitive radials (Pl XXXIX. fig. 1; Pl. XLVI). The pinnules of these two individuals are also different from those of other examples of the type. They are generally composed of moderately broad, flattened joints, the lowest of which are somewhat stouter than their successors. But in the two “Blake” specimens the pinnules are less flattened than usual, and the lower joints markedly trihedral in form, recalling, though in a less degree, the prismatic shape of the pinnules, which is characteristic of Metacrinus (Pl. XXXIX. fig. 1; Pl. XLII. fig. 4). The plating of the disk of Pentacrinus miillert (Pl. XVII. fig. 10), like that of 312 THE VOYAGE OF H.M.S. CHALLENGER. Pentacrinus decorus (Pl. XXXIV. fig. 2), is far less complete than in Pentacrinus asterius. There is no trace of the large polygonal plates on the perisome between the rays which we find in the latter species (Pl. XIII. fig. 1), and those on the ventral sur- face of the disk are small and scattered, often being mere granules. The ambulacral skeleton too is imperfectly developed. The covering plates of the pmnules do not rest upon distinct side plates, but only upon an almost undifferentiated limestone band (PL XY. figs:’8, 95 eh AV ess). 3. Pentacrinus maclearanus, Wyville Thomson, 1877 (Pl. XVI.; Pl. XVII. fig. 1). 1877. Pentacrinus maclearanus, Wyville Thomson, The Atlantic, vol. ii. pp. 123-126. Dimensions. Total length (fide C. W. T.), : . : : - 13°00 cm. Length of stem, rounded off at twelfth ode, : : . . 34:00 mm. Diameter of stem, . 5 F : é , Sed) ie Longest cirrus (twenty-five Femey é 2 ; : : 5 eNO Diameter of calyx, . : , . ; ; ; 4 9:00. Length of arm (sixty-eight joints), . : : ioe ee SS0:00RF Length of pinnule on first free brachial (ten conte : ; : i00%5.; Length of pinnule from middle of arm (fifteen joints), 5 ; > 1400) ;; Description of an Individual.—Stem short and pentagonal, with rounded angles, terminating below at the twelfth node. The internodes consist of only one or two comparatively thin joimts. Nodal joints thicker, with enlarged and prominent angles ; the cirrus-sockets, occupying almost their whole height, are circular or slightly oval in form, with a well-defined rim which extends downwards on to the infra-nodal for a variable distance. The cirri consist of twenty to twenty-five stout joimts of tolerably equal size, with a small terminal claw and no opposing spine. Interarticular pores scarcely visible. Basals rhomboidal, just in contact laterally, and extending slightly downwards over the uppermost stem-joints. Rays and their subdivisions in close lateral contact, the joints as far as the tenth or twelfth brachial having flattened sides. The two outer radials united by syzygy. Primary and secondary arms each of two joints also united by syzygy. Total number of arms thirty-one, 7.e., usually six to each ray in the following order —2,1; 1,2; palmar axillaries being generally developed only on the two outermost of the four secondary arms. A tertiary axillary in one ray. The two lower brachials united by syzygy, the epizygal bearing a pinnule. No other syzygies on the arms, which consist of about seventy short and wide, oblong joints, overlapping very slightly at the base. The lowest pinnules are much shorter than their successors, and have only ten or twelve joints, the basal ones being trihedral and the outer ones flattened. The middle pinnules much longer, with about fifteen more rounded joints. REPORT ON THE CRINOIDEA. 313 The disk is only partially visible, but seems to have a tolerably regular pavement of small plates. Arm-groove exceedingly narrow, the ambulacral plates being limited to the pinnule-bases. The pinnules have well defined covering plates with occasional faint indications of side plates. Colour in spirit, brownish-white. Locatity.—Station 122, August 10, 1873; lat. 9° 5’ N., long. 34° 50’ W.; 350 fathoms; red mud. One specimen. Remarks.—The leading characters of this elegant species were well described by Sir Wyville Thomson in The Atlantic. Its nearest allies are Pentacrinus miilleri (Pl. XIV.), Pentacrinus wyville-thomsoni (Pl. XVII. fig. 1), and Pentacrinus alternicirrus (Pl. XXV.), all of which it resembles very closely in the regularity and grouping of the arm-divisions. The stem, however, is totally different from that of Pentacrinus wyville- thomsoni with its long internodes, and the number of arms is also greater than is usually the case in this species. Pentacrinus miilleri and Pentacrinus alternicirrus approach it most closely, having relatively short internodes; but the arrangement of the cirri on the stem of the latter species distinguishes it at once. Pentacrinus maclearanus closely resembles some specimens of Pentacrinus miilleri in the shape of the nodal joints; but, apart from the characters of the internodes, it is readily identified by the unusual shortness of its lowest pinnules and the more rounded form of the joints in the later ones. The close approximation of the nodal joints, and the downward curvature of the cirri, together with the slight downward extension of the basals and the grouping of the arms, are of interest as recalling the Liassic Hxtracrinus briareus. Only four cirri are present at one of the nodes, the fifth socket being totally absent. This indicates a variation in the direction of Pentacrinus alternicirrus, which has only two or three cirri at each node (Pl. XXVI. figs. 1-3). 4. Pentacrinus wyville-thomsoni, Jeffreys (Pl. XVII. figs. 2-6; Pls. XVHI.—XXIV. ; Pl LVil; fee): 1870. Pentacrinus Wyville-Fhomsoni, Jeffreys, Proc. Roy. Soc., 1870, vol. xix. p. 157. 1872. Pentacrinus wyville-thomsoni, Wyville Thomson, Proc. Roy. Soc. Edin., vol. vii. p. 767; and The Depths of the Sea, p. 444. Dimensions. Total length, . : : ‘ 3 ‘ . 24:00 cm. Longest stem, rounded off at een node: : . ; c . 155-00 mm. Shortest stem, rounded off at fifth node, 5 : ‘ : ~ S0;000%; Diameter of stem, : : ; ‘ : ‘ : 3°50) 5, Longest cirrus (nineteen ite)! : ; d 3 : 3» 24:00) 55 Diameter of calyx, 3 A ; : ; : c ; ‘205s Diameter of disk, F E : : . : . OSD ss Length of arm (seventy Aine : : : LOO; OOM Length of pinnule on first free brachial (ten wountay é : - ce AKONONO) Length of pinnule from middle of arm (twenty-one joints), 5 BEE) gy, (ZOOL. CHALL, EXP,—PART XXxU,—1854.) Ti 40 o1l4 THE VOYAGE OF H.M.S. CHALLENGER. N.B,.—Examples of this species have been distributed to several museums, and only a few have come into my hands; so that the first three of the measurements given above must not be taken as indicating the whole range of variation throughout all the individuals which were dredged by the “ Porcupine.” Stem smooth and moderately robust, but of no great length. The upper part is pentagonal with rounded angles ; but the lower portion of an old stem is almost perfectly circular. Thirty to forty, and occasionally more, internodal joints with crenulated edges which are less distinct below, Nodal joints enlarged, with sharp angular ridges which stand out prominently between the cirrus-sockets. These are transversely oval, and occupy the whole height of the nodal joint, which projects outwards over the upper edge of the infra-nodal, while the supra-nodal is slightly grooved to receive the bases of the stout cirri. These consist of about eighteen tolerably equal, smooth, and thick joints, the lowest of which are broader than their successors, especially in mature individuals. Terminal claw small, without an opposing spine. The lowest limit of the interarticular pores is a little on either side of the fourth node. Basals pentagonal, but sometimes approaching the triangular, wider than high, and forming a closed ring. The rays and their subdivisions in close lateral contact, the first five or six joints after the distichal axillary having flattened sides, The two outer radials united by syzygy. Fourteen to twenty-two arms, distichal axillaries being often absent, and palmars very rare. Primary and secondary arms each of two joints united by syzygy ; the first two brachials united in the same way, the epizygal bearing a pinnule. The arms of about seventy smooth, oblong joints in which syzygies are very rare. The first pinnules quite short, consisting only of nine or ten joints, the lowest of which are broad and flat, the later ones longer and more slender. The following pinnules increase rapidly in size, and soon become long and tapering, consisting of about twenty smooth, elongated joints, the lowest of which are slightly flattened. Disk completely covered with a pavement of small plates, as is the brachial perisome above the muscular bundles. Arm-groove moderately wide, and bordered by a discontinuous series of ambulacral plates, The pinnule-ambulacra have covering plates, but very ill defined side plates. Colour grass-green, becoming white in spirit, which acquires a purplish-red tinge. Locality H.M.S. “‘ Porcupine,” 1870. Station 17; lat. 39° 42’ N., long. 9° 43’ W.; 1095 fathoms ; ooze; bottom temperature, 39°°7 F. About twenty specimens. Also the “Talisman,” 1883; off the Morocco Coast: and again off Rochefort ; lat. 45° 59’ 30” N., long. 6° 29’ 30” W. of Paris; 1500 metres (800 fathoms). Remarks.—This fine species was first obtained by Dr. Gwyn Jeffreys during the “Porcupine ” expedition of 1870 ; and it was dedicated by him to his friend and colleague Sir Wyville Thomson in the general account of the voyage which was published in the REPORT ON THE CRINOIDEA. 315 Proceedings of the Royal Society. It was not described, however, till the year 1872, when Sir Wyville contributed a notice of the “ Porcupine” Crinoids to the Royal Society of Edinburgh ; and in the following year he reproduced this description in The Depths of the Sea, together with a woodcut which gives a very fair idea of the principal char- acters of the type. All the entire specimens obtained were dredged at Station 17; but a few fragments of stem and arms were also met with at Station 174 (740 fathoms), . together with ten specimens of Antedon lusitanica. Thirty specimens were recently dredged by the “Talisman” in 1500 metres off Rochefort. Dr. Gywn Jeffreys’ records that “ portions of the arms occurred in several other of the ‘ Porcupine’ dredgings on the Lusitanian coasts; and joints of apparently the same species have been found by Prof. Seguenza in the Zanclean formation or older Pliocene near Messina.” The latter point, however, can hardly be properly decided without a careful study of both types. In the structure of the ray-divisions and arms, Pentacrinus wyville-thomsont is closely related to Pentacrinus miilleri, Pentacrinus maclearanus, and Pentacrinus altermcirrus, especially the latter; but it is at once distinguished from them all by the shape of the nodal joints, the short stout cirri which they bear, and the great length of the internodes which separate them. It is also remarkable for the manner in which the stem ends below in a nodal joint which is closed up beneath and rounded off, as shown in Pl. XXII. fig. 27. According to Sir Wyville Thomson? “all the stems of mature individuals of this species (which were dredged by the ‘ Porcupine’) end uniformly in a nodal joint, surrounded with its whorl of cirri, which curve downwards into a kind of grappling root (Pl. XIX. fig. 1). The lower surface of the terminal joint is in all smoothed and rounded, evidently by absorption, showing that the animal had for long been free” (Pl. XXIL fig. 27). The positions of this terminal nodal joint and the corresponding length of stem in three individuals which I have examined are as follows :—stem 80 mm. long, terminating at the fifth node ; stem 90 mm. long, terminating at the sixth node; stem 155 mm. long, terminating at the seventh node. The zoologists of the “Talisman” claim to have proved, however, that Sir Wyville Thomson was wrong in his belief that the individuals dredged by the “ Porcupine” were leading a semi-free existence, loosely rooted in the soft mud. In one of a series of popular articles by Mons. H. Filhol,’ a member of the “ Talisman” expedition, it is stated that Sir Wyville came to this conclusion after having examined one of the “ Porcupine” specimens ; and a free translation is given of the last sentence of the paragraph just quoted, from which, however, the words “in all” are entirely omitted. It is thus made to appear as if Sir Wyville had drawn his conclusions from the condition of only one example of Pentacrinus wyville-thomsoni, which is very far from being the case; while he also stated in the next paragraph to that quoted by Filhol that he had remarked 1 Proc. Roy. Soc., 1870, vol. xix. p. 157. 2 Proc. Roy. Soc. Edin., vol. vii. p. 767; The Depths of the Sea, p. 444. 3 Explorations sous-marines, Voyage du “Talisman,” La Nature, No. 568, April 19, 1884. 316 THE VOYAGE OF H.M.S. CHALLENGER. ce the same character “as occurring in some specimens of Pentacrinus miilleri,” 2.e., the type now known as Pentacrinus decorus. Filhol continues, however, ‘‘nous avons constaté, apres avoir remonté des débris de roches, que ces animaux vivaient, contrairement 4 ce que l’on avait cru pouvoir supposer, complétement fixés par des cirres recourbés se détachant de larticulation terminale de la tige. Ces sortes de crochets se soudent en quelque sorte avec le fond sur lequel ils reposent et il faut les briser pour les détacher, Par conséquent les Pentacrinus Wyville- Thompsons (sic), que lon a recontrés libres, avaient di étre arrachés & la suite de quelque accident du fond sur lequel ils vivaient, car il parait bien difficile d’admettre que les mémes animaux en des points divers de l’océan aient des modes d’existence differents.” The observations here recorded are undoubtedly of great value ; but the conclusions drawn from them by Filhol appear to me to be somewhat rash. The “Talisman” speci- mens of Pentacrinus wyville-thomsoni seem to have been living on a stony or rocky bottom ; and in fact Prof. Perrier’ records that “plusieurs ont été ramenées avec les cailloux sur lesquels ils sont fixés.” There can be no question therefore that Pentacrinus wyville-thomsont lives in a permanently fixed condition on a hard bottom. But the “accident” which is supposed by Filhol to have liberated some fifteen fixed individuals must have been of a rather extensive character ; and it must further have taken place at a sufficiently long time before they were dredged by the ‘“‘ Porcupine” for the lowest nodal joint of one of them to have lost its natural appearance (Pl. XXIL. fig. 20) and have become enlarged and rounded as shown on Pl. XXII. fig. 27. But in other specimens the lowest nodal joint is far less modified, It retains its pentagonal shape and the thickened rim of the syzygial face, in the centre of which there is a small rounded tubercle covering the opening of the central canal. If all these specimens had been detached by one general “accident” anterior to the arrival of the “ Poreupine’s” dredge and tangles among them, their lowest nodal joints should haye been in the same condition and not in different stages of modification. The same “accident” must have happened to the Pentacrinus decorus of the Caribbean Sea and to the Pentacrinus maclearanus of the Challenger dredgings, both of which were described by Sir Wyville as having the stems closed up at a modified nodal joint ; but Filhol makes no reference whatever to these two types. He does not appear to dispute the fact that the “Porcupine” individuals of Pentacrinus wyville-thomsoni were free when captured; but he regards the observations of the “Talisman” as proving that this condition was not a natural one. Sir Wyville? believed that although the Pentacrinus, like the young Comatula, “ was doubtless attached in its early days, it appears to have finally parted from its attachment, and to have led a free life;” and he pointed out that the syzygial union of the stem-joints at the nodes facilitated the rupture of the stem, just as is the case with the syzygies in the arms. His } LExpédition du Talisman, Revue Scientifique, No. 24, December 15, 1883, p. 741. * Sea Lilies, The Intellectual Observer, August 1864, pave REPORT ON THE CRINOIDEA., 317 theory accounts for the varying conditions of the lowest nodal joint which are presented by different individuals; while the “accident” hypothesis of Filhol’s does not explain this fact at all, unless he means that some individuals had become detached at one time and some at another. But this is precisely what Sir Wyville believed ; only he regarded it as a natural event corresponding to the separation of the centro-dorsal of a Comatula from the rest of the stem below it, which appears to me to be a more rational explanation of the facts than that suggested by Filhol. It is possible that the “accident” referred to by the latter author may not mean the fracture of the stem at a syzygy beneath a nodal joint as I have supposed above, but a separation of the stem from its anchorage by the lowest whorl of cirri. This would account for the modification of the nodal joint in the “ Porcupine” specimens ; for in the figure which Filhol gives to illustrate the mode of attachment of those dredged by the “Talisman,” the lowest nodal joint is represented as not in contact with the rock beneath, to which its cirri are soldered ; so that it might very well have been thickened and rounded in the manner described above. But this supposition, while removing one difficulty, only introduces another. The “ Porcupine” specimens were living on a bottom of ooze at a depth of 1095 fathoms, considerably greater than the 1500 metres (800 fathoms) at which the “Talisman” examples were discovered on a rocky or stony bottom. Now in the first place, the cirri could not solder themselves to this ooze with such firmness that they would break rather than loose their hold; and secondly, there is no trace of such a connection in the cirri borne by the modified lowest nodal joint of any of the ‘‘ Porcupine” specimens. For in some individuals (PL XIX. fig. 1) they are as perfect as those at the nodes above them, and not broken as they were in the detached specimens dredged by the “Talisman.” In the case of Rhizocrinus, however, the attachment of the radicular cirri to stones and shells by slight calcareous expansions is well known (PI. X. fig. 15). All the Challenger Pentacrinidze, with one exception, were dredged from mud or ooze, and though the stems of several of them terminate below in a rounded nodal joint as in the “Porcupine” examples of Pentacrinus wyville-thomsoni, I have seen no traces of their being attached by the cirri of the lowest whorl soldering themselves to the bottom, as described by the French zoologists. The condition of four species of Pentacrinus which I have carefully examined with reference to this point appears to me to show conclusively that these observations have by no means the general application which is claimed for them. The internodes of Pentacrinus wyville-thomsoni are very long, while the cirri are short (Pl. XIX. fig. 1), so that only those of the lowest whorl can come in contact with anything beneath the lowest nodal jomt. But the case is far different in many other species, among which I select four for special consideration, as they are represented by individuals in which the lowest whorls of cirri are better preserved than usual. In the present condition of many of the specimens several of the cirri on the stem are more or less broken; and though in the 318 THE VOYAGE OF H.M.S. CHALLENGER. case of the lowest whorls this may be due to the cirri having been soldered to the bottom by calcareous expansions, I have never seen any traces of such a condition. In the first place, there is a stem-fragment of Pentacrinus asterius, consisting of a few internodal joints with a nodal joint beneath them which is somewhat worn and has its central canal closed up by a low rounded tubercle ; so that it must have been detached for some time from the infra-nodal joint which completed the syzygy. But all the cirri borne by this modified nodal joint are perfect throughout their whole length, nearly 70 mm., and were most certainly not soldered to the bottom at the time the animal was captured. Then again, in a fine Pentacrinus miilleri from Martinique with a stem 120 mm. long, which is closed below at the thirteenth node, all the cirri of this node are perfect from the base to the terminal claw. They reach 50 mm. in length, and are spread out in different directions, two being curved sharply upwards, while the others are more or less horizontal. Their general appearance is very similar to that of the long cirri of Antedon phalangium. But not one of them shows any trace of having been soldered to the bottom. The cirri of the next four whorls above are all long enough to have touched the bottom had the animal been attached like the individuals of Pentacrinus wyville- thomsoni dredged by the “Talisman.” Hight of these twenty cirri, four in the first whorl, two in the next, and two in the highest one, are now more or less broken; but this is clearly due to accident, and not to the fracture of an attachment. The same may be said of a specimen of Pentacrinus miilleri in the Natural History Museum, which has a stem 135 mm. long, with several of the lower cirri remaining unbroken; while the under surface of the twelfth nodal joint at which the stem ends is worn and somewhat rounded, and bears two or three attached Foraminifera. The animal cannot, therefore, have been attached by the base of the stem, though the cirri may have been soldered to the bottom ; but their appearance is against this supposition. The same remarks apply to Pentacrinus alternicirrus, in which the cirri reach 50 mm. in length. Those of the four or five lowest whorls turn more or less directly downwards, and all reach below the level of the terminal nodal joint, which may be anywhere between 47 and 155 mm. from the calyx. But none of these cirri in any of the twelve individuals which I have examined show any signs of having been soldered to the bottom. Many of them are now broken; but others are quite perfect, though they must have been in contact with the bottom, had the animals been permanently anchored like the “Talisman ” examples of Pentacrinus wyville-thomsoni. The single Pentacrinus dredged by the Challenger on hard ground belonged to this species; and as all the cirri of the lowest whorls are more or less broken, it is quite possible that they may have been torn away from a permanent attachment to the bottom. Another conclusive argument against the general application of the “Talisman” observations is afforded by the condition of the single specimen of Pentacrinus maclearanus which was dredged by the Challenger from a REPORT ON THE CRINOIDEA. 319 bottom of red mud (Pl. XVI. fig. 1). The cirri, though short, are very closely set, and those of the five lowest whorls bend downwards underneath the last nodal joint and interlace with one another so as to form a kind of basket-work just like that beneath the centro- dorsal of a Comatula with many cirri, such as Antedon eschrichti. This led Sir Wyville Thomson ' to remark that “from the attitude of the cirri and from the appearance of the end of the stem there can be no doubt that this specimen is complete, that it is mature, and that it was living in an unattached condition.” I do not well see how this statement can be disputed. Neither do I understand the difficulty of admitting that the mode of life of a Pentacrinus may vary in different localities. The Comatule are fixed when young, and semi-free when mature, attaching themselves by their cirri to various objects; but some species (Actinometra jukesi and Actinometra stellata, &c.) eventually lose their cirri altogether, and must then live an absolutely free life. The Paleozoic Agassizocrinus and Edriocrinus were attached when young, but subsequently became perfectly free. Con- sidering that these great changes take place during the life of a single individual, I fail to see the difficulty of admitting that a particular species of Pentacrinus can adapt itself to the conditions of its existence, some young individuals fixing themselves permanently when they have the opportunity; while ethers living on soft ooze in deeper water separate themselves from their original anchorage and lead a partially free existence, being only attached temporarily, just as a Comatulais. A precisely similar case to that of Pentacrinus wyville-thomsont is presented by Pentacrinus decorus. Some individuals are firmly fixed to telegraph cables by the spreading base of their stem, while others have been found in the semi-free condition. Circumstances alter cases ; and the question of the natural freedom of the individual represented in Pl. XIX. fig. 1, which has five perfect cirri on a rounded nodal joint at the base of the stem, is by no means negatived, because the “Talisman” found several others attached by calcareous growths round the cirri of the lowest whorl. The French zoologists, however, appear to consider that this observation proves Sir Wyville to have been wrong; whereas, on the contrary, the dredgings of the Challenger and the “ Blake” have confirmed his views in the most satisfactory manner.’ Except at the lowest nodal joint the cirri of Pentacrinus wyville-thonsoni appear to be usually directed upwards (Pl. XVUL. figs. 1,3; PL XIX. fig. 1); and the supra-nodal joint is accordingly slightly grooved for the reception of the cirrus-bases (Pl. XIX. figs, 3, 4; Pl XXII. fig. 17) instead of the infra-nodal joint as is so markedly the case in Pentacrinus blakei and Pentacrinus decorus (Pl. XXXL. figs. 1, 3; Pl. XXXIV. fig. 1; Pl. XXXVL), in which the cirri are usually directed downwards. In this respect, there- fore, Pentacrinus wyville-thomsoni presents an approach to the genus Metacrinus, in 1 The Atlantic, vol. ii. p. 126. 2 Much of what has been written above would have appeared more suitably in Chapter II. pp. 18-22, where the mode of life of the Pentacrinide is discussed. But as Filhol’s article did not appear till after this chapter had gone to the printers, and did not come under my notice till five months later, I have been obliged to take up the subject again. 320 THE VOYAGE OF H.M.S. CHALLENGER. which the upward direction of the cirri and the grooving of the supra-nodal joint ae tolerably constant characters (Pl. XXXVIII.; Pl. XXXIX. figs: 18;.0'5 (Pls ka ea. ALY. ; PL XLVII. figs: 1, 2) BE Ravine): Another small point of resemblance between the European Pentacrinus and the Pacific Metacrinus is the slight tendency sometimes shown by the basals of the former to send median downward extensions over the interradial ridges at the top of the stem (Pl. XVII. -fig. 2), for this character is very generally distinctive of Metacrinus (Pl. XXXUX: figs T 5 PL OLa i ehieseels Be) Pl, XLVIII.).. The basals of Pentacrinus wyville-thomsoni are almost always markedly pentagonal, the height being decidedly greater in the middle than at the sides, where, however, it is usually distinctly appre- elable (EL XVM fie 3.5 PLAS thes a6, 7; PL XX. fig. 3). Sometimes, however, they become almost triangular in outline (Pl. XVIIL. figs. 1, 2), and one or more of them occasionally fail to meet their fellows, a variation which is more frequently met with in Pentacrinus miilleri (Pl. XV. figs. 1, 2) and Pentacrinus naresianus (Pls. XXVIIL, XXIX.). The number of arms in Pentacrinus wyville-thomsoni is comparatively small, being sometimes as low as fourteen ; for two or even three of the rays may have no axillary but the third radial, as is sometimes the case in Pentacrinus decorus (Pl. XXXV.); and the distichal axillaries, when present, rarely occur all round the cup (Pl. XVIII. fig. 3). The examples figured in Pl. XVIII. figs. 1, 2, and Pl. XIX. figs. 1, 6, 7, are some of those with the greatest number of arms, a tertiary (palmar) axillary being occasionally present beyond the distichal ; but I do not know of any specimen in which the number of arms exceeds twenty-two. : The disk (Pl. XVII. fig. 6) is closely covered by a pavement of anambulacral plates, several of which are pierced by water-pores. These are almost entirely absent in the anal interradius, in the proximal part of which the plates are closer set than usual, and arranged into two lateral groups. At first sight these look like large single plates, and are suggestive of orals, but they become resolved on further examination into small and very closely set plates. The ambulacra of the disk are protected by irregular plates which cover them in completely in the dry state. They are more regularly arranged on the arms, but are discontinuous on alternate sides between the pinnule-bases (Pl. XVII. fig. 4) ; and the perisome covering the muscular bundles is likewise plated, as in the allied Pentacrinus alternicirrus (Pl. XXVII. fig. 6). The covering plates of the pinnule- ambulacra are not very distinctly marked off from the lateral calcareous band, especially at the bases of the pmnules; and this band itself is but very imperfectly differentiated into side plates (Pl. XVII. figs. 2, 3). | Unhke many of the Pacific Pentacrinide, which were white when fresh, living examples of Pentacrinus wyville-thomsoni have a beautiful grass-green colour. This becomes duller in spirit, which acquires a purplish-red tinge. Prof. Moseley kindly REPORT ON THE CRINOIDEA. 321 examined some of it with.the spectroscope, and found the usual bands of pentacrinin. A few specimens which have not been kept in the dark, but have been more or less exposed to light, have bleached completely white. 5. Pentacrinus alternicirrus, n. sp. (Pls. XXV., XXVI.; Pl. XXVIL figs. 1-10). Dimensions. Total length, . ; = 5 : 6 , - 195 mm, Longest stem, rounded off at eeeentih node, . : ; : a Ges, Shortest stem, rounded off at eleventh node, . : ; : oi aie, Diameter of stem, é 5 5 6 5 F 2 A oa Longest cirrus (thirty joints), . : : 5 - . 5) PA Diameter of calyx, ; : ; : 5 . ; 5 Ds Diameter of disk, : : : : ; ; at hes Length of arm (eighty joints), : : : : LOOR Length of pinnule on first free Bevetaal (eleven Foirita) : : : ap EOS Length of pinnule from middle of arm (twenty-one joints), 5 : ay peal oes Stem smooth, short, and pentagonal, with rounded angles. Four to nine (usually five or six) internodal joints with crenulated edges. The nodal joints bear two and three cirri alternately, those at one node corresponding to the positions of the absent cirri at the nodes next above and below. Cirrus-sockets nearly circular, occupying the Whole height of the nodal joint, and extending upwards on to the supra-nodals. Infra- nodals scarcely modified at all. The sockets are deeply hollowed and have prominent lateral rims, owing to the angles of the joint between them being produced outwards and rounded. Cirri composed of about thirty stout joints, the lowest of which, after the first four, are somewhat longer than their successors. The terminal claw is moderately large, and has no opposing spine, but the ventral surface of the later joints is a little uneven. The lowest limit of the interarticular pores is between the fifth and eighth nodes, Basals rhomboidal, extended slightly downwards, and produced laterally so as to meet their fellows in the re-entering angles of the calyx. The rays and their subdivisions in close lateral contact ; the joints as far as the sixth or eighth brachial having flattened sides. The two outer radials united by syzygy. About thirty (twenty-five to thirty-two) arms, usually six to each ray, the axillaries being limited to the outer divisions. Primary, secondary, and tertiary arms (the latter very rare) each of two joints united by syzyey. The two lowest brachials united in the same way, the epizygal bearing the first pinnule. Arms of about eighty smooth, oblong joints with syzygies at intervals of three to eight (usually five or six) joints. The ah one between the ninth and twenty-sixth brachials. First pinnules quite short, consisting only of ten or eleven joints, the lowest of which are broad and flat, and the later ones long and slender. This inequality gradually disappears as the pinnules increase in length towards the middle of the arm, where they are tapering (Z00L. CHALL. EXP,-—PART xxx11,—1884.) fi 41 322 THE VOYAGE OF H.M.S. CHALLENGER. and styliform, consisting of about twenty smooth, flattened joints with sharp dorsal edges. The disk is completely covered with a pavement of small plates, as is the brachial perisome above the muscular bundles. Arm-groove moderately wide, and bordered by a discontinuous series of ambulacral plates. The pinnule-ambulacra have covering plates, and sometimes moderately distinct side plates. Colour in spirit, yellowish-white, sometimes retaining a rosy tinge. Localities. —Station 171, July 15, 1874; near the Kermadec Islands; lat. 28° 33’ §., long. 177° 50’ W.; 600 fathoms; hard ground; bottom temperature, 39°°5 F. One specimen. Station 214, February 10, 1875; offthe Meangis Islands ; lat. 4° 33’ N., long. 127° 6’ E.; 500 fathoms; blue mud; bottom temperature, 41°°8 F. Several specimens. Uncertain—Station 210, January 25, 1875; off the Panglao and Siquijor Islands ; lat. 9° 26’ N., long. 123° 45’ E.; 375 fathoms; blue mud; bottom temperature, 54°'1 F. Some of the fifteen specimens sent to me were without labels; and I strongly suspect that this species, together with Pentacrinus naresianus, three examples of which are without labels, are those referred to by Sir Wyville, who recorded in his journal that four specimens of two species of Pentacrinidee were dredged at Station 210; for the collection contains no specimens at all with the label of this Station. Remarks.—Pentacrinus alterncirrus, like Pentacrinus wyville-thomsoni, appears to be pre-eminently one of those which lives in a semi-free condition, the stem having been broken at a nodal joint, the syzygial face of which becomes worn and more or less rounded, and has its central canal closed up. The following list shows the position of this terminal nodal joint and the corresponding length of the stem in twelve specimens. Stem, 47 mm. long and terminating at the 11th node. att) 3 £ (the: 3) 0S 5 thee. » G64 % 5 llth ,, Oe rs . llth ,, OD p . 12th ,, a 180 5 12th ,, mn OY) 5 . 12th ,, a th! 7 i 12th ,, yO) . . 14th ,, ul 3 ¥ 14th ,, 5 ls} * 5 16th ,, The remarkable arrangement of the cirri in this species distinguishes it at once from all the other recent Pentacrinide. Except that the symmetry is pentamerous instead of tetramerous, the arrangement recalls that of the leaves on the stem of a Labiate plant. In one case only have I found any irregularity. The eighth whorl has its two regular cirri like the sixth, together with an additional one which therefore comes to be on the REPORT ON THE CRINOIDEA. 320 same side of the stem as the third cirrus in the seventh whorl. But the ninth whorl has only two cirri instead of three; and is the beginning of a new cycle; for the tenth whorl is not.like the sixth with only two cirri, but resembles the irregular eighth one with three. In the same way the eleventh whorl is like the ninth and not the seventh, and so on. The absence of cirri at some of the nodes of Pentacrinus alternicirrus is the more striking as there are regularly five cirri at each node in all the Pentacrinide, both recent and fossil, with three exceptions. These are Pentacrinus bronnii, Hagenow,’ from the White Chalk of Riigen, and Pentacrinus didactylus, VOrbigny,’ from the Eocene of Biarritz, both of which have only two cirri at a node; while under the name of Penta- crinus tridactylus, Quenstedt* has described another Tertiary stem-fragment from Le Vit in the south of France, which has a verticil of three cirri only. It is just possible that if longer pieces of these stems were known they might show the same regular alternation in the positions of the successive cirrus-whorls which is so striking in Pentacrinus alterni- cirrus. But whether this be the case or not, the departure from the pentamerous arrangement of cirri which is so characteristic of the Pentacrinidee is not a little remark- able. For verticils of two cirri alternating with one another in position sometimes occur in both Bourgueticrinus and Mesocrinus ; though the structure of the stem in these genera is totally different from that of Pentacrinus, as has been fully explained in Chapter II. In consequence of the absence of two or three cirrus-sockets, the nodal joints of Pentacrinus alternicivrus depart considerably from the symmetrical form presented by those of other Pentacrinide, as is shown in Pl. XXVI. figs. 13, 14, and Pl XXVII. figs. 2, 8. The last two represent syzygial faces of two successive nodes in their relative positions, the two empty sides in fig. 2 being occupied by sockets in fig. 3. Apart from the arrangement of the cirri, Pentacrinus alternicirrus resembles Penta- crinus maclearanus and Pentacrinus miilleri in the shortness of the internodes, while it agrees with both these species and also with Pentacrinus wyville-thomson in the reeularity and the grouping of the arm-divisions. The general arrangement of the crown of arms (Pl. XXY.) is most like that of Pentacrinus wyville-thomsoni (Pl. XIX. fig. 1); and the long middle pinnules of the two species are very similar, while the characters of the perisomatic skeleton are almost identical (compare Pl. XVII. figs. 2-4, and Pl. XXVII. figs. 4-6). The leading characters of Pentacrinus alternicirrus appear to be very constant, the South Pacific specimen from near the Kermadees being in no way distinguishable from those dredged off the Meangis Islands. This is a striking contrast to the variations of 1 Monographie der Riigenschen Kreide-Versteinerungen, Newes Jahrb. f. Mineralogie, Jahrg. 1840, p. 663, Taf, ix. ig. . - : See d’Archiac, Description des fossiles recueillis par M. Thorent, dans les couches 4 nummulines des environs de Bayonne, Mém. Soc. géol. de France, 2m° sér., t. ii. 17° partie, 1846, p. 200, pl. v. figs. 16a, 17a, 3 Encriniden, p. 268, Tab. 99, fig. 170. 324 THE VOYAGE OF H.M.S. CHALLENGER. Pentacrinus decorus and Pentacrinus miilleri in the Caribbean Sea. There are nearly always five or six internodal joints in the stem, and I have only noticed two cases of an arm-division consisting of more than two joints united by syzygy. One has three joints, of which the first two form a syzygy, and in the other there are four, those of each pair being united by syzygy. In the arms, however, the position of the syzygies, after that at the base, is exceedingly variable. But this is always the case in the few species of Penta- erimus which have syzygies in the arms, the contrast between them and the Comatule being very striking in this respect. Pentacrinus alternicirrus appears to inhabit moderately deep water, the depths at the two Stations from which it is recorded being respectively 500 and 600 fathoms; while at the doubtful Station 210 the depth was 375 fathoms. Five of the individuals dredged at Station 214 (Meangis Islands) were infested with encysted Myzostomas, as were also many of the Comatulz. In one specimen no less than eight arms bore more or less perfect cysts of Myzostoma pentacrini, von Graff, two of them having two cysts a short distance apart. In other cases the cysts were principally formed in the skeleton of the pinnules by Myzostoma deformator, von Graff, as shown in Pl. XXVII. figs. 7 and 8; while figs. 9 and 10 represent cysts formed in the substance of the arm. 6. Pentacrinus naresianus, n. sp. (Pl. XXVII. figs. 11-13; Pls. XXVIIL—-XXX.). Dimensions. Total length of largest specimen, stem broken at thirtieth node, - - 54:00 cm. Length of this stem, : : : F j : SoS 00a, Diameter of stem, . . ; ; : : ; 5:00 mm. Longest cirrus (thirty-five Rote) ‘ : 2 Z : » 20,0075 Diameter of calyx, . : : ; : é ; fs ome Length of arm (eighty joints), : : 3 ; 4 f LDO00se Length of first pinnule (twelve joints), : : : : 8:50 ,, Length of pinnule from middle of arm (twenty-two soite). ; : 5 AO Stem long and ‘smooth, of a rounded pentagonal or circular form. Light to eighteen (usually about ten or twelve) internodal joints with but slightly crenulated edges. Nodal joints high, not projecting outwards at the angles, but deeply hollowed by the cirrus-sockets, which have nearly circular facets and terminate far below the upper edges of the nodal joints. Infra-nodals deeply grooved to receive the cirrus-bases, so that the sockets appear to have pyriform downward extensions. Cirri moderately slender, of thirty to thirty-five tolerably uniform joints, all but the lowest of which have one or two blunt projections on the dorsal edge. Lowest limit of the interarticular pores between the fifth and eighth nodes. Basals small, triangular or pentagonal, sometimes meeting laterally and sometimes 1 Zool. Chall, Exp., part xxvii. pp. 62-66, 1884. REPORT ON THE CRINOIDEA. 325 not, owing to the radials being prolonged slightly downwards over the upper stem- joints. Ten arms only, but the rays are in close lateral contact, the second radials being united all round, while the axillaries and the first two brachials have flattened outer sides. Second and third radials and thé first two brachials respectively united by bifascial articulation. Arms of about ninety joints,’ the lower ones bluntly wedge- shaped and the later joints nearly oblong or squarish, with raised distal edges so as to overlap slightly. A syzygy in the third brachial, another between the sixth and fifteenth jomts, and others at intervals of four to twelve (usually seven to nine) joints, The proximal face of the epizygal forms a sharp angle projecting backwards into the retreating distal face of the hypozygal, the dorsal surface of which projects forwards into that of the epizygal. The first pinnules are quite short, consisting only of about twelve joints, the lowest half of which are broad and flattened and the later ones quite small. This inequality gradually disappears as the pinnules increase in length, the lower joints becoming less broad and the later ones more elongated. Those on the middle of the arm are long and styliform, consisting of about twenty joints, the first of which are much broader than the rest. Disk covered with numerous, closely set, irregular plates. These extend on to the arms at the sides of the ambulacra, which are altogether above the arm-groove, and are protected by a continuous series of tolerably regular covering plates. There are no definite side plates on the pinnules, but only a narrow band of limestone with its edges cut into teeth which bear the covering plates. Colour in spirit, pinkish-white. Localities.—Station 170, July 14,1874; near the Kermadee Islands; lat. 29° 55’ os long. 178° 14’ W.; 520 fathoms; volcanic mud; bottom temperature, 43° F. Two quite young specimens, Station 170a, July 14, 1874; near the Kermadee Islands; lat. 29° 45/ S., long. 178° 11’ W.; 630 fathoms; volcanic mud; bottom temperature, 39°5 F. 10. interruptus, n. sp. seer { complete g girdle. Usually eight distichals. { nodal : 4 a ; | Rounded stem without ridges. Usually ten dis- The ‘* Vega” specimen. [| Joints. [ tichals. stemsharp | incised. Le tuberastis, 7p. and pro- + duced out- | Eleven internodals with slight horizontal ridges. Infra- wards. [ nodals not incised. Angles of { Seven internodals with median tubercles. Infra-nodals not ; 1 } stewarti, P. H. C. REPORT ON THE CRINOIDEA. 345 1. Metacrinus angulatus, n. sp. (Pls. XXXVIIL., XXXIX.). Dimensions. Greatest length of stem, terminating at the thirty-fifth node, : . 38°50 cm. Diameter of stem, . ‘ é é i : , 5:75 mm. Longest cirrus (fifty-seven eae ¢ ; ; : d PAD BHOIU) vip Diameter of calyx, . 5 ; 5 : : ; : 8:25 ,, Diameter of disk, . é , : : Sy) ADA Length of arm (one hundred and ei penta : ; : 28 90:00, Length of large distichal pinnule (twenty joints), . : 3 4) :25:0003 Length of first pinnule after tertiary axillary (twelve joints), : 5 AOHOOD. 5, Stem robust, with a sharply pentagonal outline. Hight to twelve internodal joints with but slightly crenulated edges. Their faces are distinctly stellate, while the angles are sharpened and slightly produced outwards ; and their sides bear strong horizontal ridges, the edges of which are coarsely denticulate. Nodal joints more distinctly stellate in outline and without horizontal ridges. The cirrus-facets reach closer to their upper than to their lower edges, while the supra-nodal joints are slightly incised to receive the bases of the large cirri, which are mostly directed upwards, and are longest at the twelfth node. They usually consist of forty-five to fifty-five stout joints, which are very uniform in appearance except at the two ends. The lower joints are quite short, and the distal edges are longer than the proximal ones, so that the joints seem to have slight dorsal projections at their distal ends. The interarticular pores terminate between the tenth and twelfth nodes. Basals widely hexagonal, united into a complete ring, and rather prominent on the exterior of the calyx. They are much higher in the middle line than at the lateral edges, and the lower angle is often produced considerably downwards over the upper stem- joints. Four radials, the first comparatively short and the second a syzygy with a pinnule on the epizygal, the third also bearing a pinnule and the last axillary. Rarely more than three divisions of the rays, which are in close apposition, being only separated by the bases of the large lower pinnules. Forty to fifty arms, generally consisting of about one hundred slightly overlapping joints beyond the last axillary. Primary arms of six to ten distichals (usually eight or nine), of which the second or third is a syzygy. Secondary arms of ten to fourteen palmars, sometimes as many as twenty, the third of which is usually a syzygy. ‘Tertiary arms rare; consisting when present of fourteen to thirty joints, the third of which is a syzygy. There is generally a syzygy in the third brachial of the free arm. Another somewhere between the tenth and thirtieth brachials, and others at intervals of six to twelve joints. A pinnule on the epizygal of the second radial, and on the first joint after each axillary. The first pinnules, as far as the beginning of the secondary arms, are much larger than their successors, consisting of about twenty joints, the lowest of which are (ZOOL. CHALL, EXP,—PART xxxu.—1884.) Ti 44 346 THE VOYAGE OF H.M.S. CHALLENGER. very massive, and generally somewhat cuboidal ; while the next few are narrower with flattened sides, but still of great thickness in a dorsoventral direction. The thickness gradually diminishes, and the outer part of the pinnule consists of moderately long, somewhat flattened joints, with the dorsal edges sharpened and projecting slightly forward over the bases of their successors. The distichal pinnules on the outer sides of the ray are longer and have somewhat larger joints than those borne by the radials. Beyond the distichal axillary, the size of the pinnules gradually decreases, the lower joints becoming at first prismatic and then flattened, but remaining distinctly larger than their successors for some little distance beyond the palmar axillaries. The later pinnules are short and styliform. The disk bears numerous small scaly plates, which are more thickly grouped on the | anal tube than elsewhere. Disk-ambulacra strongly but irregularly plated ; those of the arms distinctly above the arm-groove, and supported by regular bifid plates which become ciiferentiated on the pinnules into covering plates and ill defined side plates. Colour when fresh—the stems almost white, and the crowns light yellow or light reddish-orange (Moseley) ; in spirit, white or whitish-brown. Locality.—Station 192, September 26, 1874; in the Arafura Sea, off the Ki Islands ; lat. 5° 49’8., long. 132° 14’ E.; 140 fathoms ; blue mud. Seven specimens, and possibly more. Remarks. This species is readily distinguished from its nearest ally (Metacrinus cingulatus) by the characters of its stem-joints (Pl. XXXIX. figs. 3-11). They are much more sharply stellate than in that type (Pl. XLI. figs. 1-3), having deeper re-entermg angles; while the horizontal ridges on the sides of the internodal joints are generally not continuous, but interrupted at the angles, which are somewhat produced outwards (Pl. XXXIX. fig. 3). One specimen presents a curious variation in this respect. The horizontal ridges on the thicker joints are enlarged so as to have a some- what diamond shaped aspect, with more or less produced lateral angles (Pl. XXXIX. fiz, 11); and when this ridge is large it shows itself very plainly in a terminal view of the joint-face, outside the line of teeth (compare Pl, XXXIX, figs. 8 and 11). In this specimen too the downward extension of the basals over the upper stem-joints is especially well marked, and the supra-nodal joint is rather more hollowed to receive the cirrus-bases than it is in the type. The stems of five specimens all terminate below in a nodal joint. In two cases there appears to have been an attached portion of stem ~ beneath ; for the surface of this lowest nodal joint is comparatively fresh and its central canal visible; but in the other three stems this surface is somewhat worn, and I cannot make out the opening of the central canal, which appears to have been closed up, the animal living in a semi-free condition like Pentacrinus wyville-thomsoni, Pentacrinus maclearanus, or Pentacrinus alternicirrus. The respective lengths of these stems are as follows :—(1) 38°5 cm. long, closed at the thirty-fifth node; (2) 23°5 em. long, closed REPORT ON THE CRINOIDEA. 347 at the twenty-fourth node; (3) 22°5 em. long, closed at the twenty-fifth node. The individuals of this species present various forms of monstrosity, some of which have already been mentioned :—(1) The presence of six joints in one ray, of which the second and the axillary are syzygies, thus approaching the other group of Metacrinus species. (2) The presence of eleven radials on one ray, which recalls the irregularities of the Palzocrinoids. (3) The eighth joint of one of the primary arms is not a distichal axillary as usual, but it is swollen and bears a slightly larger pinnule than the preceding joint, so that it resembles an axillary with unequal faces. Fourteen joints further on there is an axillary which corresponds to that on the secondary arms of other rays. (4) The presence of a second smaller anal tube at the side of the ordinary one (Pl. XXXIX. fig. 2), an individual of Myzostoma wyville-thomsoni, von Graff, having attached itself between the two. (5) The two arm-trunks borne by one of the palmar axillaries each have - a syzygy in the third brachial, and then unite again into a single trunk. The fourth joint of the right-hand arm has the shape of an axillary reversed, 7.e., it has two proximal faces, one of which meets the epizygal of the third brachial, and the other the fourth brachial of the left-hand arm. It bears a pinnule on its left side, and as it is the fourth joint of one arm-trunk, and the fifth of the other, the ordinary sequence of the pinnules is uninterrupted, and continues normal throughout the rest of the arm which is borne by this reversed axillary. 2. Metacrinus cingulatus, n. sp. (Pl. XL., Pl. XLI. figs. 1-4). Dimensions. Length of stem to ee node, : 3 : : . 95°00 cm. Diameter of stem, . : : : ; : : 5°50 mm. Longest cirrus (fifty joints), . : : ; : . “A MOL-OOMN,; Diameter of calyx, . : ; : : : A : 8:00 ,, Diameter of disk, . : : : : é =» 48:00) 5, Length of arm (one hundred sointaye : 3 : 5p SABO) Sy, Length of large distichal pinnule (twenty-five foie) ‘ ; ee 2o:00n Length of first pinnule after tertiary axillary (fifteen joints), : 5 MORON I Stem robust, with a sharply pentagonal outline. Six to fifteen (usually eight to twelve) internodal joints, with moderately crenulated edges. Their faces are bluntly stellate, with shallow re-entering angles; while their sides bear strong horizontal ridges which are slightly more prominent at the angles of the stem, and are often marked by irregular indentations. The nodal joints are more distinctly stellate, and have no ridges except at the angles and where the cirrus-facets are absent. These reach closer to the lower than to the upper edges of the nodal joints, but the incision of the supra-nodals is fairly distinct. The cirri have about forty to fifty tolerably uniform joints, and are 348 THE VOYAGE OF H.M.S. CHALLENGER. longest between the eleventh and twelfth nodes. The interarticular pores end between the eighth and tenth nodes. Basals prominent, more or less extended downwards. Radials four, the second a syzygy. Rarely more than four divisions of the rays, giving forty or fifty arms, which consist of about one hundred joints beyond the last axillary, the basal ones slightly over- lapping. Primary arms of six to eight, or sometimes ten distichals, of which the second or third is a syzygy. Secondaries of ten to fifteen (usually twelve to fourteen) palmars, the third generally a syzygy. Tertiary arms rare, consisting of fourteen to twenty-six (usually eighteen to twenty) joints, the third of which is a syzygy. In rare cases there is another axillary after twenty joints more. There is generally a syzygy in the third brachial of the free arm, another between the seventh and twenty-sixth, and others at intervals of six to eighteen joints. The distichal pinnules have large outer joints, and are therefore larger on the whole than those on the radials, though the basal joints are generally less massive than in the radial pinnules. All the pinnules, and especially the lower ones, have a serrate dorsal edge. The disk bears numerous small plates, which are not very closely set, except in the anal interradius. The ambulacra of the disk and arm- bases are supported by irregular elongated plates, the latter being distinctly above the arm-groove, with a few ambulacral plates at their sides. The brachial ambulacra pro- tected by smaller bifid plates, which become differentiated on the pinnules into covering and side plates. Colour when fresh—the stems almost white, and the crowns light yellow or light reddish-orange (Moseley) ; in spirit, white. Locality. —Station 192, September 26, 1874 ; in the Arafura Sea, off the Ki Islands ; lat. 5° 49’ S., long. 132° 14’ E.; 140 fathoms ; blue mud. Two specimens. Remarks.—This species is at first sight not unlike Metacrinus angulatus (PI. XXXVIIT.), having about the same number of internodal joints in the stem, and a nearly identical arrangement of the arm-divisions. The stem-joints, however, are very different in the two types. The horizontal ridges, which are interrupted at the angles of the stem in Metacrinus angulatus (Pl. XX XIX. figs. 3, 11), are usually continued right round the joints in Metacrinus cingulatus (Pl. XLI. figs. 1, 8); and they appear also as enlargements of the angles of the nodal joints (Pl. XLI. fig. 2), which are much less sharp than in Metacrinus angulatus (Pl. XXXIX. fig. 4). As a rule too there are generally slightly fewer joints between the successive axillaries of the dividing rays than in the latter species, but the character of the arms and of the pinnules which they bear is very much the same in both. The two specimens of Metacrinus cingulatus which were obtained by the Challenger differ somewhat in their characters, and each exhibits a certain amount of variation. In the smaller individual there is an irregularity in one of the rays. The fourth or axillary radial is not articulated to the preceding joint, as is usually the case, but the two REPORT ON THE CRINOIDEA. 349 are united by syzygy. The third radial therefore, being a hypozygal, bears no pinnule. But the normal number of pinnules, one on each side of the ray, is still maintained ; for the second radial, itself a syzygial joint, bears a pinnule on each side. The stem of this specimen, which is broken at the bottom, tapers slightly downwards, and has tolerably regular internodes, with five cirri at each node in the usual way. The stem of the other individual, however, does not decrease in size at its lower end, which terminates in a nodal joint with a freshly exposed under surface. The inter- nodes of this stem are very irregular in length, and generally consist of one or two joints more than in the smaller specimen, while the development of cirri at the nodes is extremely irregular. No less than ten of the thirty-three remaining nodes have one or more cirri deficient, as shown in the following Table :— Node. Missing Cirri. Node. Missing Cirri. 5th 2 20th 2 8th 1 24th 2 9th 3 27th 4 10th 1 30th 4 13th 1 33rd 2 In the lower part of the stem there is no trace of the absent sockets, which are replaced by ridges like those on the internodal joints; but in the middle and upper parts the socket is present, though imperfectly developed, especially at the fifth node. At the thirteenth, the place of the socket is entirely taken up by a group of sessile Cirripedes (Verruca). Metacrinus murray?, n. sp. (Pl. XLI. figs. 12-17; Pl. XLIL.). Dimensions. Length of stem to eighteenth node, é 6 % - . 184:00 mm. Diameter of stem, . ; ; : 0 : : 615), Longest cirrus (forty-eight rome ‘ : j c : ~ 43008 Fs Diameter of calyx, . ; . : : : : Jan LHIOOM, Diameter of disk, . : oy apa O0. Length of arm (one hundred and fifteen pone above pane eallar) a LOO:00R: Length of pinnule on second radial (fifteen joints), . : : ne LCROOR rs Length of first palmar pinnule (seventeen joints), : 2 23:00, Length of first pinnule after tertiary axillary (steven Some) : et OOS Description of an Individual.—Stem robust and of a rounded pentagonal form, with very shallow re-entering angles. Internodes composed of thirteen joints, with smooth sides and faintly crenulated edges. The supra-nodal joints are slightly incised, but the 350 THE VOYAGE OF H.M.S. CHALLENGER. articular surfaces of the wide and deep cirrus-sockets are limited to the nodal joints, which are markedly stellate in form, though their angles are not produced outwards. The infra-nodals are also deeply notched by the downward extensions of the cirrus- sockets. Cirri composed of about forty-five joints, almost all of which, and especially the basal ones, are wider than long. JInterarticular pores disappear at the thir- teenth node. The basals appear externally as rhomboidal knobs, but they extend laterally to meet their fellows in the re-entering angles of the calyx. Four radials, of which the first is relatively short and wide, and the second a syzygy. The rays divide four, and occasionally five, times, giving about ninety arms. These consist of about one hundred and ten joints above the tertiary axillaries, and, like the rays, are quite smooth at the base, only becoming serrate towards the extremities. Four or rarely six distichals in the primary arms; eight or ten palmars in the secondaries; and the tertiaries of eight to eighteen (usually twelve or fourteen) joints. The next division (when present) occurs after about fourteen or sixteen (ten to twenty-four) joints more. The third joint after each axillary is usually a syzygy. Another between the tenth and thirtieth brachials, and then an interval of five to thirteen joints between successive syzygies. The two radial pinnules, and also those on the lower distichals, have one or two massive basal joints; but the following joints, though long and moderately thick, are very much flattened laterally, so that the dorsal surface is reduced to a mere edge. The longest pinnules are those immediately above and below the distichal axillary, and are less compressed than their predecessors, so that the joints are more uniform in appear- ance, though the lower ones are relatively large and cuboidal. The palmar pinnules are all long ; but the size begins to diminish beyond the axillaries, rapidly at first, and after- wards somewhat slowly. The disk is thickly covered with plates which are small and more closely set upon the anal tube than elsewhere. Brachial ambulacra not much above the arm-groove, and supported by bifid plates which are differentiated into side and covering plates about the middle of the pinnules. Colour in spirit—calyx and arm-bases grey ; arms and stem nearly white, but the tips of the arms light brown. Remarks.—The fine specimen which forms the subject of the above description has unfortunately lost most of its arms in the usual way, viz., by fracture at one or other of the lower syzygies. In the frequency of its ray-divisions, in the constant presence of supra-palmars, and in the diameter of its stem, it ranks among the largest types of recent Pentacrinide, and I have much pleasure in associating it with the well known name of Mr. John Murray. The species which it most nearly resembles is Metacrinus nobilis, from Station 192, near the Ki Islands; though the two forms differ considerably in the characters of the REPORT ON THE CRINOIDEA. o51 stem, as may be seen by comparing figs. 5-7 and figs. 15-17 on Pl. XLI. The whole stem of Metacrinus murrayi is slightly grooved along the interradial lines (fig. 15), so that the pentagonal outline of the internodal joints has shallow re-entering angles (fig. 17), while those of the nodal joints are sharper than in Metacrinus nobilis (figs. 6, 16). The modification of the supra-nodals is about the same in both types, but the infra-nodals of Metacrinus nobilis are more cut away to receive the cirrus-bases than are those of Metacrinus murray? (Pl. XLI. figs. 5, 15). The internodes of the stem in the latter species are slightly longer, and the interarticular pores reach farther from the cup than in Metacrinus nobilis, but there are fewer joints in the primary arms, and the dorsal edges of the pinnules are less serrate (Pl. XLI. figs. 9,10; Pl. XLIL figs. 2, 3). Of the two remaining species with smooth stems and four radials, Metacrinus superbus is readily distinguished from Metacrinus murrayi by the great size of the cirri‘and the roughness of the arm-bases; while the stem of the smaller Metacrinus varians has considerably shorter internodes and nearly flat sides. The habitat of Metacrinus murray: is unfortunately unknown, no record having been kept of the Station at which it was dredged. It may perhaps be one of the two species which are noted in Sir Wyville Thomson’s diary as having been obtained at Station 210 (Panglao), no Crinoid having reached me with the label of this Station. On the other hand, it may have been found at Station 192 (Ki Islands) or Station 214 (Meangis Islands). A Cirripede attached to one of the cirri was identified by Dr. Hoek as Scalpellum balanoides. This species is abundant at Station 192; and Dr. Hoek had seen individuals from no other locality. Under these circumstances one would almost have been justified in assigning Metacrinus murrayi to that Station; but Dr. Hoek has also recognised Scalpellum balanoides on a cirrus of Metacrinus varians which I sent him from Station 214. Either of these Stations therefore, to say nothing of Station 210, might have been the habitat of Metacrinus murray?. 4, Metacrinus nobilis, n. sp. (Pl. XLI. figs. 5-11; Pl. XLIIL.). Dimensions. Length of stem to twenty-fifth node, 3 : : 5 . 28°00 em. Diameter of stem, . : 5 : : : : 7:00 mm. Longest cirrus (forty-eight vomits c é : , : > » 46:005%; Diameter of calyx, . ; : : . E ; 4 9:00) 5 Diameter of disk, . 3 5 210005, Length of arm (one hundred and Fn noite abies btary Sie, a EO) Length of large distichal pinnule (twenty-three joints), F : Fei AAO! 5 Length of first pinnule after tertiary axillary (thirteen joints), 2 - ) 14:00),,; Stem robust, with a simple pentagonal outline and smooth, flat sides. Usually ten or twelve internodal joints, with shghtly crenulated edges. Nodal joints bluntly stellate, with 352 THE VOYAGE OF H.M.S. CHALLENGER. wide sockets which take up their whole height and encroach considerably both on infra- nodal and on supra-nodal joints. The cirri have about forty-five tolerably uniform joints, and are longest between the twelfth and fourteenth nodes. The interarticular pores end at the tenth node. Basals prominent, with slight downward extensions. Radials four, rather strongly convex, the second a syzygy. Generally four, and sometimes five divisions of the rays, giving seventy arms or more. These have from one hundred to one hundred and twenty joints beyond the last axillary, and are smooth at the base; but their middle and outer portions are markedly serrate in the medio-dorsal line. Primary arms usually of five distichal joints, one or sometimes two of which are syzygial. Hight or nine palmars in the secondary arms, the second or third of which is a syzygy. Tertiaries of twelve to twenty joints (usually about fifteen), with the third a syzygy. In a few cases there is another division after about twenty joimts more. There is generally a syzygy in the third brachial of the free arm ; another between the twelfth and thirty-seventh brachials, © and others at intervals of four to thirteen joints. The pinnules on the radials and lower distichals are all very long and much com- pressed above the enlarged basal joints, while their terminal portions have a serrate dorsal edge. The following pinnules, as far as the tertiary axillaries, have wide and somewhat prismatic basal joints like those lower down on the rays, but with more curved sides, and consisting of more uniform joints, the dorsal edges of which project forwards. Disk rather closely plated, especially in the anal interradius and along the ambulacra. Brachial ambulacra partially withdrawn into the arm-groove, and supported by irregularly shaped plates. Side plates not differentiated till near the ends of the pinnules. Colour when fresh—the stems almost white, and the crowns light yellow or lght reddish-orange (Moseley) ; in spirit, white, with traces of ight brown. Locality. —Station 192, September 26, 1874; in the Arafura Sea, off the Ki Islands ; lat. 5° 49’ §., long. 132° 14’ E.; 140 fathoms; blue mud. Two large specimens, one of which has lost all its arms, and one smaller varietal form. Remarks.—This fine species is readily distinguished from Metacrinus murray: by its flat ungrooved stem (Pl. XLI. fig. 5), with shorter internodes and more markedly incised infra-nodal joints (Pl. XLIII. fig. 1). The primary arms are generally longer than in that type, and the extremities of the arms and pinnules more serrate. Metacrinus varians, Which resembles Metacrinus nobilis in having a flat ungrooved stem (Pl. XLVII. figs. 6, 8), is altogether a smaller type with shorter internodes and no axillaries after the palmars, so that the number of arms does not exceed forty; while the large Metacrinus superbus has many more cirrus-joints and its arm-bases uneven, owing to the thickness of the proximal and distal edges of the joints, REPORT ON THE CRINOIDEA. 353 Together with the two large specimens of Metacrinus nobilis which agree very well in their general characters, there was also obtained a fragment of stem which appears to belong to this species. The internodes are much shorter than in the type, and contain a number of thin joints which are evidently newly formed ; while there are traces of inter- articular pores in its upper portion. As, however, the cirri are all directed downwards it is possible that the individual was in a semi-free condition, with a comparatively short stem like Pentacrinus maclearanus (Pl. XVI.) or Pentacrinus alternicirrus. At one of the nodes a cirrus-socket is totally undeveloped; and the same appears to be the case at another node farther down the stem, where a large Verruca covers the whole of one side of the nodal joint, also extending on to those above and below it. Besides the two large specimens mentioned above there was also obtained at Station 192 a smaller individual which agrees so closely with the type of this species that I find some difficulty in separating it, although the two forms appear at first sight to be totally different. The stem, which is much more rounded than in the type (Pl. XLI. figs. 7, 8), is barely 5 mm. in diameter; and although the internodal joints are generally smooth, their angles are sometimes slightly produced outwards, while indications of horizontal ridges appear here and there below the twelfth node. The grouping of the arm-divisions is essentially the same as in the larger type, so far as can be made out in the fragmentary condition of the dried specimen; and in default of further information respecting its characters, I do not see how to classify it otherwise than as an immature or smaller variety of Metacrinus nobilis. 5. Metacrinus varians, n. sp. (Pl. XLIV.; Pl. XLVII. figs. 6-12). Dimensions. Length of stem to thirty-second node, ; ; : : . 94:00 cm. Diameter of stem, . : F F : ; ; : 5:25 mm. Longest cirrus (fifty joints), . A 0 : 5 : = 40:00, Diameter of calyx, : 0 ; : 4 S500; Length of arm (ninety joints beyond palmar axillary), : 0 oo 00; Length of distichal pinnule (eighteen joints), : , ; ee LGLOO Ms, Length of first pinnule after palmar axillary (nineteen joints), F A LOO lass Stem moderately robust, with a simple pentagonal outline, its sides being nearly flat, and scarcely grooved at all. Six to ten internodal joints (usually eight or nine), with smooth sides and but faintly crenulated edges. Nodal joints bluntly stellate, with moderately wide sockets which take up their whole height, extending well downwards on to the infra-nodals and also upwards on to. the supra-nodals. Cirri of forty-five to fifty very uniform joints, the lowest of which are but little wider than their successors ; the (ZOOL, CHALL, EXP,—PART Xxxu,—1884.) li 45 304 THE VOYAGE OF H.M.S. CHALLENGER. lower cirri not specially shorter than the upper. Interarticular pores end between the fifth and seventh nodes. Basals variable, sometimes flattened and almost oblong, with wide upper angles and no downward extensions; sometimes very prominent and sharply pointed below. Radials usually four, with rather flattened surfaces, the second a syzygy. But there are several variations from this type. The rays divide three, or rarely four, times, giving about forty arms. These have about ninety joints beyond the last axillary, and are moderately smooth at the base; but their terminal portions become strongly serrate in the medio-dorsal line. Primary arms of six to ten (usually six or eight) distichals, the second or third of which is a syzygy. Secondary arms of ten to twenty-five (usually twelve or fourteen) palmars, the third of which is generally a syzygy. On the outer side of the ray there is sometimes, but rarely, another axillary after from fourteen to twenty- six joints, of which the second or third isa syzygy. ‘There is generally a syzygy in the third brachial of the free arm; another between the seventh and eleventh brachials, and others at intervals of two to seventeen (usually four to eight) joints. Some of the radial pinnules are large, with massive and cuboidal lower joints ; but the four following pinnules are smaller, and the basal joints, though broad and somewhat flattened, are not as a rule specially massive, becoming comparatively inconspicuous after the palmar axillary. Their dorsal edge is sharp but not strongly serrate. Disk well plated, both at the sides of and between the ambulacra. Brachial ambulacra but little above the arm-groove, and supported by large plates which soon pass into dis- tinct side and covering plates on the pinnules. Colour in spirit, greyish-white ; “of a uniform dusky purple when fresh” (Moseley). Locality.—Station 1704, July 14, 1874; near the Kermadec Islands; lat. 29° 45’ 8., long. 178° 11’ W.; 630 fathoms ; volcanic mud; bottom temperature, 39°°5 F. One specimen, but doubtful. Station 214, February 10, 1875; off the Meangis Islands; lat. 4° 33’ N., long. 127° 6’ E.; 500 fathoms; blue mud; bottom temperature, 41°°8 F. Three (four ?) specimens. Remarks.—The individual figured on Pl. XLIV:, which is very well preserved, was obtained at Station 214, off the Meangis Islands, together with two other examples which have the arms broken off at the syzygy in the second radials. A fourth mutilated individual, which had lost the disk and two rays, reached me in a bottle which also con- tained one specimen of Metacrinus wyvillii, and the label of Station 1704 (near the Kermadecs). On the other hand, the figured specimen of Metacrinus wyvillii and also that of Metacrinus varians were together in a jar with the label of Station 214 (Meangis Islands). There is no question from other evidence that Metacrinus wyvilliz, like Pentacrinus naresianus, occurs at both Stations ; but I am a little uncertain about the single specimen of Metacrinus varians. For the two species, although distinctly REPORT ON THE CRINOIDEA. 355 differentiated by Sir Wyville Thomson, and drawn on separate plates, do not seem to have been kept apart by him ; and it is just possible that one individual of each may have been accidentally interchanged. An additional reason for believing that this doubtful example of Metacrinus varians really belongs to Station 214, and not to Station 170a, is that both the Cirripedes (Scalpellum balanoides and Verruca nitida) which are attached to the stem and cirri are recorded from Station 214, but not from Station 170a. The four individuals of Metacrinus varians which the collection contains present a considerable amount of variation in several points of structure. One of them has a cirrus missing at one of the nodes on the stem, while two more are undeveloped at another node. The radials vary greatly, and present the following modifications, the second being a syzygy in every case :— Three radials, the axillary a syzygy. Four radials, the axillary simple (type). Four radials, the axillary a syzygy. Five radials, the axillary a syzygy. In correspondence with this there is a great amount of variation in the size of the basal joints of the lowest pinnules. For there may be sometimes only one, and some- times two of these appendages in each interradial space; and in the latter case the basal joints of one or both of them are much smaller than usual. ‘The size of the distichal pinnules is also to some extent affected in the same way, the first one being frequently much smaller at the base than its successors. Metacrinus varians is a species that stands very much by itself among those forms of Metacrinus which have normally but four radials. It is smaller and less robust than all the species previously described. From Metacrinus angulatus and Metacrinus cingu- latus it differs in the absence of the markings on the sides of the stem-joints (eine eConee, 3 11; PL ALL he Pi XV fie. 6), and in the slightly shorter internodes ; while in the types with smooth stems (Metacrinus nobilis, Metacrinus murrayi, and Metacrinus superbus) the internodes are considerably longer than in the more slender Metacrinus varians, and the grouping of the arm-divisions is different. 6. Metacrinus moseleyi, n. sp. (Pls. XLV., XLVI). Dimensions. Length of tapering stem of young individual to twenty-third node, . . 138:00 mm. Diameter of lower part of stem, - ° ° 5 : : 3°00 ,, Longest cirrus (forty-five joints), . : ; an: : 7) oox00) 5: Diameter of calyx, . : : : ; OO. Length of the first radial ements (fifteen joints), : : ; 1124510) Ge Length of first pinnule after palmar axillary (thirteen crated) : . 950 ,, 306 THE VOYAGE OF H.M.8. CHALLENGER. Stem slender and of a rounded pentagonal form, without lateral grooves. Usually seven internodal joints with scarcely crenulated edges and more or less marked horizontal ridges, which are especially prominent on the larger joints. The nodal joints are deeply hollowed by the cirrus-sockets, and have their angles slightly produced, so as to be lobate in form. ‘The sockets extend but very slightly either on to the supra- or on to the infra- nodals. Cirri composed of forty to forty-five joints, the basal ones of which are not specially broad, while their successors are often a trifle longer than wide. Interarticular pores end at the sixth node. Basals relatively very large and convex, pentagonal or almost oblong in form. (N.B., the preceding description is based upon one individual only.) Radials very variable, sometimes only three or four, but usually five or even six, with the second and sometimes also the fourth a syzygy. Most of the rays divide three times, giving from thirty to forty arms, the longest unbroken ones of which consist of about fifty joints beyond the palmar axillary. The dorsal surface of the skeleton is rather uneven, owing to the overlapping of the joints and the elevation of their distal edges, especially between the radials and the palmar axillaries. Primary arms of six to twelve (generally eight or ten) joints. Secondaries of seven to sixteen (usually ten or twelve) palmars. The third joint, but not unfrequently the fourth or fifth, after each axillary is generally a syzygy. The next syzygy in the free arms may be anywhere between the fifth and the thirtieth brachials, and others follow at very irregular intervals. The radial pinnules vary in appearance according to their position, but the two lower joints are larger and more cuboidal than the rest, which are flattened laterally. The distichal and palmar pinnules are shorter than those on the radials, and gradually decrease in size. Their dorsal edge is sharpened, but the two lower joints are broad and expanded, as is also the case, though in a less degree, with the first pinnules on the free arms. The disk is thickly covered with comparatively large plates, and the ambulacral skeleton is well developed. The brachial ambulacra are withdrawn into the narrow arm- groove, and but little plated independently of those of the pmnules, which have squarish side plates and large, rounded, covering plates. Colour—a uniform dusky purple when fresh (Moseley), light grey when dry, almost white in spirit. Locality.—Station 214, February 10,1875; off the Meangis Islands; lat. 4° 33’ N., long. 127° 6’ W. ; 500 fathoms ; blue mud ; bottom temperature, 41°°8 F. Two specimens. Remarks—I have much pleasure in associating this pretty little species with the name of Prof. H. N. Moseley, F.R.S. Two specimens of it were obtained by the Challenger. One of them, represented on Pl. XLV., is evidently immature, as shown by the relatively large size of its basals, the length of its lower and middle cirrus- REPORT ON THE CRINOIDEA. 357 joints, the frequent alternation of thick and thin joints in the stem, and the small size of its arms. The larger specimen, figured on Pl. XLVI., appears to have met with an accident since it was drawn, for it came into my hands in the dry state, having lost its stem and basal ring. The characters of the rays and arms, however, are so essentially similar to those of the smaller individual that I have no hesitation in regarding the two as identical. The characters of the stem as a whole come nearest to those of Metacrinus cingulatus (compare Pl. XLL figs. 1-3, and Pl. XLV. figs. 2-6). In both cases there is a continu- ous horizontal ridge round each of the mature internodal joints, but the articular faces are more lobate in Metacrinus cingulatus (Pl. XLI. fig. 3) than in Metacrinus moseley (Pl. XLV. fig. 2). The same is the case with the nodal joints which have more produced angles and consequently deeper cirrus-sockets in Metacrinus moseleyi than in the larger species. The characters of the cup, however, are quite different in the two types, that of Metacrinus cingulatus being extremely regular in the number of its radials, while in Metacrinus moseleyi there may be as few as three or as many as six. The only other species which resembles it in this respect is the large Metacrinus rotundus* from Japan, which has a smooth stem, with much longer internodes. The ten rays of the two indi- viduals of Metacrinus moseleyi are constructed as follows :— * One of three joints, the second and the axillary both syzygies. * One of four joints, the second and the axillary both syzygies. Three of five joints, the second a syzygy. Two of five joints, the second and fourth syzygies. One of six joints, the second a syzygy. Two of six joints, the second and fourth syzygies. The number of primitive joints in the ray, therefore, before the union of one or more pairs by syzygy, varies from five to eight, just as in other species of Metacrinus. The irregularity which distinguishes Metacrinus moseleyi thus lies rather in the mode of union of the primitive joints to form syzygial pairs than in any excess or defect of their number; though as a general rule there are either five (Metacrinus angulatus) or eight (Metacrinus wyvillii), and not both types in the same individual. Two very anomalous instances which oceur in the dry specimen are marked with an asterisk in the above list. In the first case the five primitive radials have become reduced to three, owing to the union of the last four into two syzygial pairs. In Metacrinus angulatus (Pl. XXXIX. fig. 1) the fourth primitive jomt remains distinct from the axillary to which it is united by muscles, and bears the second pinnule. But on this abnormal ray of Metacrinus moseleyi these two joints are united by syzygy, and as the hypozygal of a syzygy never bears a pinnule, the natural condition would have 1 See Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. ii. p. 437. 358 THE VOYAGE OF H.M.S. CHALLENGER. been the suppression of the second radial pinnule. As a matter of fact, however, it is present on the epizygal of the second radial, which thus bears two pinnules, one on each side, A similar instance of two pinnules on one joint also occurs in Metacrinus cingulatus (ante, p. 349), and recalls the condition of certain Paleocrinoids. In the next ray to this one the fourth radial, which is a syzygial joint, is also the axillary; and although the first and second radial pinnules are present as usual, the axillary epizygal bears a pinnule in addition to the two primary arms. This pinnule, however, really belongs to one of the first distichal joints, which is much smaller than its fellow, and does not reach the outer edge of the arm at all. The consequence is that the first pinnule of the primary arm is borne by its second and not by its first joint, as is usually the case. Apart from these irregularities, the larger dry specimen of Metacrinus moseleyi appears to be tolerably normal in its character. But the smaller individual is different. The stem tapers downwards, being only 3 mm. wide at the twenty-third node, but rather over 4 mm. at the twelfth node. The arms too are much malformed by com- mencing Myzostoma-cysts, either in the arm itself, or in the base of a pinnule, as shown uP) RV, fies % 7. Metacrinus wyvillii, n. sp. (Pl. XLVIL figs. 1-5; Pl. XLVIIL). Dimensions. Length of stem to thirty-fourth node, é : : : - 27:00 cm. Diameter of stem, . : . : : : : 4:50 mm. Longest cirrus (forty-five faints), ; : - : . et oieOOkes. Diameter of calyx, . : : : : : 7:25 =, Length of arm (ninety joints beyond palmar Aare ), . 5 = OO;00Ra.. Length of first distichal pinnule (fifteen joints), . ; : ot Al S2O0NNE: Length of first pinnule after palmar axillary (sixteen joints), . : 10:00. |; Stem pentagonal and moderately robust. Five to eight (generally seven) internodal joints, with more or less well defined horizontal ridges and slightly crenulated edges. Nodal joints bluntly stellate, with large facets of variable shape which take up their whole height, while the sockets extend on to both supra- and infra-nodal joints, especially the latter. Cirri of forty to forty-five very uniform joints, the lowest of which are but little wider than their successors, The lower cirri not specially shorter than the upper. Interarticular pores extend down to the sixth or seventh node. Basals pentagonal, large and prominent, more or less sharply pointed below, some- times being almost hexagonal. Radials usually six, with syzygies in the second and fourth. The rays, which are somewhat closely set, divide three or very rarely four times, giving nearly forty arms. These have about ninety joints above the palmar axillaries, and are almost quite smooth dorsally, except in the terminal third. Primary arms of REPORT ON THE CRINOIDEA. 359 four to ten (usually eight or nine) distichals; twelve to twenty-six, but usually not more than sixteen, palmars in the secondary arms. Sometimes, but rarely, there is another axillary after some thirteen to twenty joints more. The third joint after each axillary is generally a syzygy. The following syzygies are distributed very irregularly in the free arms. The second is between the ninth and thirtieth brachials, usually about the twelfth or fifteenth; and the others at intervals of three to twenty (generally ten or twelve) joints. The second and following radials bear pinnules of about a dozen moderately stout joints, the lowest of which are more or less massive and cuboidal, but vary considerably in size according to circumstances. The first distichal pinnule is nearly similar to those on the radials, but the following ones consist of more flattened joints, the lowest of which are much broader than their successors. This equality is very marked in the pinnules which are borne on the palmars and the lower parts of the free arms, and also in a less degree in the smaller terminal pinnules. Brachial ambulacra but little above the narrow arm-groove, and only slightly plated between the origins of the pinnule- ambulacra, which soon begin to show well defined side plates. Colour in spirit, greyish-white ; a uniform dusky purple when fresh (Moseley). Localities. Station 170, July 14, 1874; near the Kermadec Islands ; lat. 29° 45’8., long. 178° 11’ W.; 630 fathoms; volcanic mud; bottom temperature, 39°°5 F. Two specimens, one rather young. Station 214, February 10, 1875; off the Meangis Islands; lat. 4° 33’ N., long. 127° 6’ W.; 500 fathoms ; blue mud ; bottom temperature, 41°'8 F. One good specimen ; one mutilated individual, and two stem-fragments, one of which has the calyx and a portion of the arm-bases remaining. Remarks.—This species is the only Metacrinus which is known with certaimty to occur in the South as well as in the North Pacific. Although nearly resembling Metacrinus moseleyi, Metacrinus costatus, and Metacrinus nodosus in the length of the internodes of the stem and in the number of the distichal joints, it differs from them all in the other characters of the stem. The two last mentioned types have a somewhat sharply pentagonal stem, and the cirrus-facets are not so high as the nodal joints, the angles of which are much produced; while the sides of the joints are smooth or slightly tubercular (Pl. XLIX. fig. 3; Pl. LI. fig. 8). Metacrinus wyvillii, however, has a more rounded stem with horizontal ridges on the internodal joints; while the cirrus-facets occupy the whole height of the nodal joints (Pl. XLVII. figs. 1, 2). It is altogether a larger species than Metacrinus moseleyi, and has entirely different stem-joints, as is immediately evident upon comparison of the figures on Pls. XLV. and XLVII. respectively. Another good character of Metacrinus wyvillii, which is more or less visible, however, in the species mentioned above, is the peculiar enlargement and flattening against the arm of the basal joints of the pinnules immediately above the radials, and the persistence 360 THE VOYAGE OF H.M.8. CHALLENGER. of this character to far out on the arms. It is well shown in some parts of fig. 1 on BEX EU It was on a proof copy of this plate that I found the MS. name Metacrinus in Sir Wyville’s own handwriting; and I have therefore taken the opportunity of associating this elegant species with his memory. It is one of some importance on account of its occurrence at two such widely separated localities as the Kermadec Islands (Station 170) in lat. 29° 45’ S., and the Meangis Islands (Station 214) in lat. 4° 33’ N. The two specimens obtained at the former Station are both of very considerable interest. The stem of the larger one, which is 25 em. long, is broken at the thirty-sixth node, the inter- nodes being shorter than in the more northern individuals, as seven joints are the exception and not the rule. As in so many other cases, this stem tapers gradually down- wards, being almost 5 mm. wide immediately below the calyx, and less than 3 mm. at the lowest node, just above which the diminution in size is most rapid. The other specimen obtained at Station 170A is a young individual, with a head not more than 55 mm. long, and less than sixty joints in the free arms. The attached portion of the stem, which is 185 mm. long, is a trifle over 3 mm. wide just below the basals, which are relatively very large and prominent. Its diameter decreases slightly to about the fifth node, and then slowly increases again till the sixteenth node, where the stem widens rather suddenly. It reaches 4 mm. at the last joint immediately below the twenty-seventh node. The ornamentation of this stem is less well defined than in the older specimen from the same locality. In fact there is a good deal of individual variation, some of the stems from Station 214 having very well defined horizontal ridges (Pl. XLVI. figs. 1, 2), while they are rather inconspicuous on the figured specimen (Pl. XLVIII. fig. 2). One individual presents a curious amount of variation in the character of the rays. Three are normal, consisting of six joints, of which the second and fourth are syzygies ; but on one of these the usual pinnule on the epizygal of the fourth brachial is missing, though that on the next joint is present. Another ray consists of seven joints, the fifth and sixth of which bear pinnules on the same side; while the fifth ray has eight joints with no pinnule on the sixth. 8. Metacrinus costatus, n. sp. (Pl. XLVII. fig. 13; Pl. XLIX.). Dimensions. Length of stem to the twenty-fourth node, . : ; : - 20:00 cm. Diameter of stem, . c : . : : F 3°75 mm. Longest cirrus (forty-five ane : ‘ - F : 2 o2.00 Diameter of calyx, . : ‘ 5 650 ,, Length of arm (one hundred joints bay ond he maleae mailer)! : 2 d0000s Length of pinnule on first distichal (seventeen joints), j : =) LAOS Length of first pinnule after palmar axillary (twenty joints), . ae lOO REPORT ON THE CRINOIDEA. 361 Stem slender and pentagonal in outline, with slight re-entering angles. Generally seven or eight internodal joints with distinctly crenulated edges. Their relatively high sides are somewhat hollowed, and smooth or marked with faint ridges ; while their angles are sharpened and a little produced outwards, so that the whole stem is traversed by five well defined interradial ridges. The supra-nodals are but slightly incised, and the wide cirrus-facets do not reach the upper edges of the nodal joints. They likewise barely reach the lower edges, coming much nearer to them in some specimens than in others ; and the infra-nodals are scarcely grooved, so that their re-entering angles are but little more marked than those of the other internodal joints. Cirri composed of about forty joints, the first two of which are short and wide, while the eighth and a few following ones are sometimes a little longer than wide. The lower cirri do not seem to be specially shorter than the upper. Interarticular pores not visible below the tenth node. The basals (in the only specimen possessing them) appear as small rhomboidal knobs with their pointed lower extremities resting on the interradial ridges at the top of the stem ; but they extend laterally and meet their fellows in the re-entering angles between the first radials. The rays consist of six rounded joints, of which the second and fourth are syzygies, and are well separated laterally above the hypozygals of the second radials. They all divide three times, and there are generally additional axillaries on the two outer- most of each set of four tertiary arms thus produced, so that the total number of arms reaches about sixty. They consist of about one hundred joints above the palmar axillaries, and are almost smooth in the medio-dorsal line till near the ends, which are slightly serrate. The distichals, palmars, and lower brachials present a peculiarity which is, much more marked in the baseless individual than in the more normal one. The pinnule-bearing side of each joint is slightly bent outwards above the pinnule-socket, and its edge is cut into several small teeth or spines. In addition to this the front edge of each joint and the corresponding part of the hinder edge of its successor are slightly raised on one or both sides, and are also more or less spinose. These characters are perhaps most distinctly marked upon the palmars, not being fully developed upon the distichals, and disappearing a little beyond the level of the tertiary axillaries. Six or eight joimts in the primary arms ; secondaries of eight to fourteen (usually ten or twelve) palmars. The next division (when present) may be from eight to twenty (generally twelve to sixteen) joints, and in one case there is another axillary after sixteen joints more. The third joint after each axillary is usually a syzygy. The next syzygy in the free arms may be anywhere between the sixth and thirtieth brachials, after which an interval of three to eighteen joints occurs between successive syzygies. The pinnules on the radials and first distichals are large and massive, consisting of (ZOOL, CHALL, EXP.—PART XXx1I.—1884.) ii 46 362 THE VOYAGE OF H.M.S. CHALLENGER. eighteen or twenty joints, the lowest of which are cuboidal. The next few, though still very thick, are much flattened laterally and gradually diminish in width, with the lateral edges of the dorsal surface raised and thickened. The terminal part of the pinnule consists of much smaller joints, and is more or less distinctly serrate. In the pinnules of the third and the next following distichals the dorsal surface of the two or three thick basal joints is rather broad, but the following joints diminish rapidly both in breadth and in thickness. Beyond the distichal axillaries all the pinnule-joints are longer than wide, with the exception of the first two, which are much expanded, and this character is very marked in all the following pinnules till about the level of the fourth axillaries. Beyond this pomt the second and third pinnule-joints more nearly resemble their successors, though traces of the expansion of the first joint are visible for some distance farther. The disk (so far as it is visible) is well protected by plates, both on its ventral surface and on its sides, right down to the hypozygal of the second brachial. The brachial ambulacra are but little above the narrow arm-groove, and are protected like those of the large lower pinnules by very irregular plates. The terminal pinnules have well defined and rather pointed side plates. Colour—a uniform dusky purple when fresh (Moseley); in spirit, ight brownish- white. Locality.—Station 214, February 10, 1875; off the Meangis Islands; lat. 4° 33’ N., long. 127° 6’ E.; 500 fathoms; blue mud; bottom temperature, 41°°8 F. Two specimens, with Myzostoma wyville-thomsoni, von Graff. Remarks.—This elegant little species is the smallest Metacrinus which I have yet seen, with the exception of Metacrinus nodosus; and it has many points of resemblance with that type, as will be explained later. Although the stem and cup are much less robust than in Metacrinus wyvillii, the number of arms is nearly half as large again as in that species, which rarely has an axillary beyond the palmars; while in Metacrinus costatus this is generally the case on four out of the eight tertiary arms, and there may be another axillary beyond the supra-palmar. The number of internodal joints is nearly the same in the two species, being rarely less than seven in Metacrinus costatus, though sometimes falling to five in Metacrinus wyvillii. But they are totally different in their form and external markings, as will be evident from a comparison of Pl. XLVII. fies. 1-4, and Pl. XLIX. figs. 3, 4. The nodal joints are also quite different in the two species. The cirrus-sockets of Metacrinus wyvillii (Pl. XLVII. figs. 1, 2) extend both upwards and downwards on to the supra- and infra-nodal joints beyond the articular facets, which occupy the whole height of the nodal joints. But, this is far from being the case in Metacrinus costatus; and the nodal joints therefore are less deeply incised than in Metacrinus wyvillii, while their angles are much sharper and more produced outwards (Pl. XLIX. figs. 3, 5). There is also a good deal of difference between the pinnules of the two types. Both those on the radials and distichals of Metacrinus wyvillii and those REPORT ON THE CRINOIDEA. 363 . farther out on the arms are smaller than the corresponding pinnules of Metacrinus costatus ; while the lowest pinnules are smaller, smoother, and have more rounded joints than the more massive but flattened pinnules of Metacrinus costatus with their serrate ends. On the other hand, the expansion of the two basal joints in the pinnules beyond the palmar axillary is more conspicuous in Metacrinus wyvillii than in Metacrinus costatus, and the remaining pinnule-joints are distinctly stouter than in that species. There is a great amount of difference between the two specimens described above except in the characters of the stem, which are extremely constant, the number of internodal joints beg almost invariably seven or eight. In the first place the basal plates of one individual are entirely absent; and each of the radials, which are slightly higher than in the other example, has a small downward projection in the middle of its base which rests directly on the top of one of the five ridges of the stem, as shown in Pl. XLIX. fig. 2. The basals of the other example are smaller than is usually the case in the genus; but their total absence, at any rate on the exterior of the calyx, 1s a most singular anomaly. One result of it is that the position of the cirri is interradial and not radial, as is generally the case; and presumably therefore the peripheral vessels from which the cirrus-vessels are supplied have a similar position. But these peripheral vessels are continuous above with the chambers of the chambered organ, which are normally set in the direction of the rays (Pl. XXIV. figs. 5-8; Pl. LVIII. figs. 1, 2; Pl. LXII.—ch) ; while the primary axial cords of the rays start from the interradial angles of the chambered organ (Pl. XXIV. fig. 7; Pl. LVILL. figs. 1,3; Pl. LXII.—az). If the mutual relation of these organs in this anomalous specimen were only known it would very probably throw much light upon the structure of the lower part of the calyx in those Paleeocrinoids which have interradial cirri, such as Heterocrinus, Locrinus, Bary- crinus, and Belemnocrinus florifer. It is of course possible that the basals may be internal and concealed as in most Comatule and in some varieties of Hnerinus; but I cannot help thinking that if they were really present at all the cirri would be placed radially as they usually are, and not interradially as is actually the case. This baseless’ specimen presents the only irregularity in the number of the radials which occurs in the two individuals. The second radial is not traversed by a syzygy, as is invariably the case in all the other rays, though the second syzygy is in its normal position between the fifth and sixth joints of the primitive ray as in the ordinary type ; but there is no additional joint between this syzygy and the axillary, so that the ray consists of six joints with the fifth a syzyey. All the ten primary arms of this individual, however, consist of six joints, of which the third is traversed by a syzygy; while in the other specimen with a more normal calyx there is only one distichal series of this character, together with one of eight joints, of which the second is a syzygy; and the remaining six also consist of eight joints, but have a syzygy in the third. The later arm-divisions of the baseless specimen are 364 THE VOYAGE OF H.M.S. CHALLENGER. exceedingly regular, as it almost invariably has six arms above each distichal axillary arranged in the following order 2,1; 1, 2. There are only two instances of an axillary occurring on one of the inner pair of the four tertiary arms; while it is never absent on one of the outer pair. This regular arrangement recalls that already noticed in some species of Pentacrinus. But it is much less constant than in the more normal example with the regular calyx, and it is in this individual that the solitary instance of a fifth axillary occurs; while the peculiar development of spines on the lower arm-divisions is much more marked in the one without a base. The pinnule-ambulacra vary considerably in their appearance according to their posi- tion, as will be seen by a comparison of Pl. XLVII. fig. 13 and Pl. XLIX. figs. 6, 7; and it is only on the later pimnules of the arm that the side and covering plates come to be distinctly differentiated. The peculiar mode of development of the side plates on some of the larger pinnules has been already described (ante, p. 82). The same character is also visible in Metacrinus wyvillii and Metacrinus nodosus (PI. LI. fig. 12), though to a less extent. The occasional enlargement of some of the arm-joints appears to indicate that an encysting Myzostoma had commenced operations. This is probably the Myzostoma pentacrint of von Graff! It “ does not produce real cysts upon the arms of its host, but only swellings of several (three to six) joints, which gradually disappear.” It was found in abundance on Pentacrinus alternicirrus from the same Station (214) as Metacrinus costatus ; whereas the free Myzostoma wyville-thomsoni which was attached to the disk of the latter species occupied a similar position on the disk of Metacrinus angulatus from Station 192, off the Ki Islands. 9. Metacrinus nodosus, n. sp. (Pls. L., LI.). Dimensions. Length of stem to seventeenth node, : : é : . 14:00 cm. Diameter of stem, . ‘ : F : 5 ‘ 3°00 mm. Longest cirrus (forty-five acne : ; : : . 5 oho 53 Diameter of calyx, . : : ; ; $ : : 6:00 Diameter of disk, . * ‘ . : =) 12sD0 Fe; Length of pinnule on fourth radial fourteen’ joints), | 3000. Length of pinnule on first joint after palmar axillary Gime hue) : 9:00) 5 Stem slender and sharply pentagonal. Light or nine internodal joints with distinctly crenulated edges and a faint tubercle in the middle of each side. Nodals, especially in the young stem, produced outwards at the angles between the wide cirrus-facets which do not reach either edge. Supra- and infra-nodal joints both somewhat modified. Cirri 1 Zool. Chall. Exp., part xxvii. p. 68, 1884. REPORT ON THE CRINOIDEA. 365 of about forty joints, some of which (after the short and wide ones at the base) are longer than broad. The dorsal edge of the middle joints is slightly serrate, but the later ones become almost smooth. Interarticular pores end about the ninth node. Basals pentagonal and forming a closed ring, but very convex in the centre, so as to appear like rhomboidal knobs resting on the interradial ridges of the stem. Radials six, very convex, the second and fourth syzygies. Rays well separated laterally, and divide four times. Arms twelve or more to the ray, slightly serrate in the medio-dorsal line, especially in the lower divisions. Primaries of six or eight (rarely ten) joints ; second- aries of eight to fourteen palmars; tertiaries of sixteen to twenty-eight joints. The third joint after each axillary is a syzygy, and the next syzygy in the free arms is anywhere between the tenth and twenty-fourth joints ; after which the syzygies follow at intervals of five to fourteen joints. The radial pinnules, especially the first one, mostly have wide and massive basal joints with thickened edges ; but the middle joints are more compressed and the terminal ones slender. The distichal pinnules are also stout and composed of large joints; but the following ones consist of compressed and more elongated joints, the first two of which are considerably wider than the rest until some little way beyond the last axillary. The disk is covered with numerous small plates, which are much smaller and more closely set in the anal interradius than elsewhere. Brachial ambulacra above the arm- grooves, and protected by irregular plates from which the covering plates and large pointed side plates are developed on the pinnules. Colour—of a uniform dusky purple when fresh (Moseley); greyish-white in spirit. Locality.—Station 170a, July 14, 1874; near the Kermadee Islands; lat. 29° 45’ S., long. 178° 11’ W.; 630 fathoms ; volcanic mud; bottom temperature, 39°°5 F. Remarks.—Three examples of this elegant little species seem to have been obtained by the Challenger. One of them is quite young (Pl. LI. fig. 1), while the other two were in a much mutilated condition. The dissected calyx figured on Pl. L. figs. 5-18 appears to belong to the fragment represented on fig. 1 of the same Plate. It is certainly not the same as that of which the disk is shown in fig. 2. This last and a few detached arms have served as the basis of the foregoing description. The only species with which Metacrinus nodosus is liable to be confused is the little Metacrinus costatus from off the Meangis Islands (Station 214). For Metacrinus wyvillii, which also has six radials and about the same number of internodal joints, is altogether much larger and more robust. But it has a smaller number of arms than either Metacrinus costatus or Metacrinus nodosus. The difference between these two last lies chiefly in the characters of the stem, both of them having twelve or more arms on the ray, owing to the presence of axillaries on the outermost of each set of four tertiary arms, as well as on some of the inner ones occasionally. The pinnules are generally similar in the two types, and the peculiar 366 THE VOYAGE OF H.M.S. CHALLENGER. modification of the lower arm-joints above the pinnule-sockets, which was noticed in Metacrinus costatus, is also visible in Metacrinus nodosus, though to a less extent. There is a good deal of difference, however, between the stems of the two species. While the normal number of internodal joints in Metacrinus costatus is seven or eight, that of Metacrinus nodosus is eight or nine, and they are very regularly marked by a faint tubercle in the middle of each side, which is flat and scarcely hollowed at all (Pl. LI. fig. 8). In Metacrinus costatus, on the other hand, the sides of this stem are almost smooth, or only marked by a few occasional horizontal ridges, while they are distinctly hollowed between the prominent angles (Pl. XLIX. figs. 3, 4), so that the stem appears to be traversed along its whole length by five rather sharp interradial ridges. In the uppermost and growing part of the stem these ridges are much more prominent on the closely set nodal joints than on the thin internodals which separate them. But as the latter increase in thickness their interradial angles are also enlarged, so that those on the nodal joints are not specially prominent. This character is also visible in Metacrinus nodosus, both in the stem-joints of young individuals (Pl. LI. figs. 6,7) and in the growing part of the stem of the more mature specimen. But there are no strong ridges developed at the angles of the internodes, as is the case in Metacrinus costatus, so that those of the nodal joints are always more or less prominent (PI. L. fig. 4; Pl. LI. fig. 8). The side plates on the pinnule-ambulacra of Metacrinus nodosus are relatively large and pointed (Pl. LI. figs. 11, 12). They are developed in the same style as those of Metacrinus costatus (Pl. XLVII. fig. 13) from the somewhat irregular plates of the brachial ambulacra, which are not so bifid as in Metacrinus angulatus (Pl. XXXIX. fig. 13) or in Metacrinus varians (P). XLVII. figs. 11, 12). The young individual of Metacrinus nodosus, which is represented in Pl. LI. fig. 1, has a shghtly tapering stem containing sixteen nodes, at the eighth of which one cirrus- socket is undeveloped. The characters of the young stem-joints, which are shown in figs. 2-7, have been noticed already (ante, p. 291). Of the four rays remaining in this specimen only one is normal, 7.e., composed of six joints, of which the second and fourth are syzygies. In one case the fifth joint is the axillary, and in another the fourth, which is at the same time a syzygial joint like the second ; while in another ray the fourth radial is not a syzygy, though the fifth is axillary and united to it somewhat closely, so as to give almost the appearance of a syzygy-' But the presence of a pinnule on the fourth joint shows conclusively that it cannot be the hypozygal of a syzygy, as its homologue is in the next ray. This specimen is so young that the palmar axillaries are with difficulty distinguished from the ordinary joints of the secondary arms; and in some cases at any rate they seem to have been farther from the distichal axillaries than is usual in the larger indi- 1 A little too much has been made of this resemblance to a syzygy in the right hand side of the figure, fi REPORT ON THE CRINOIDEA. 367 vidual. Attached to a stem-fragment which was brought up with these individuals were a small Ophiuran and a young Turbinolian coral (Pl. LI. fig. 8). 10. Metacrinus interruptus, n. sp. (Pl. LIL). Dimensions. Length of stem to nineteenth node, . “ ‘ : é - 21°00 cm. Diameter of stem, . 3 : : : ; ; F 4:25 mm. Longest cirrus (forty-five joints), : C : : : =a 4300555 Diameter of calyx, . A : 5 : : : : 8:00 ,, Length of arm (one hundred and thirty joints beyond the palmar axillary), . 105-00 ,, Length of pinnule on second radial (twenty joints), . : : sae 2200s Length of pinnule on third distichal (eighteen joints), : F i 16:00 ,, Length of pinnule on first joint beyond the palmar axillary (eighteen joints), . 11-00 ,, Description of an Indidual.—Stem moderately slender, with a sharply pentagonal outline. Ten or eleven internodal joints with but slightly crenulated edges. Their sides are somewhat hollowed, and marked by tolerably distinct horizontal ridges. These are interrupted at the angles which generally bear very faint tubercles. The supra-nodal joints are slightly incised, but the cirrus-sockets terminate in thickened rims distinctly above the lower edge of the nodal joint. Its syzygial face, like that of the infra-nodal, is thus regularly pentagonal, as is its outline when seen from above, although the upper surface is distinctly lobate. Cirri composed of forty to forty-five very uniform joints, the lowest but little wider than their successors, few or none of which are longer than wide. The cirri are longest between the ninth and twelfth nodes; and the inter- articular pores end at the eleventh node. . Basals widely pentagonal, but not specially prominent. Radials six, with syzygies in the second and fourth. The joints are somewhat sharply rounded and relatively narrow, so that the rays are widely separated above the hypozygal of the second joint. They all divide three times; but there is a fourth axillary in two cases, so that the total number of arms is forty-two. These have about one hundred and thirty joints above the palmar axillary, the basal ones almost quite smooth, and the later joints only with very slightly raised distal edges. ‘Primary arms of eight (rarely ten) distichals, and secondaries of twelve to sixteen or eighteen palmars. In two cases there is a third division after ten and twelve joints respectively. The third joint after each axillary is a syzygy. The next syzygy in the free arms may be anywhere between the ninth and sixtieth brachials ; after which an interval of six to fifteen joints occurs between successive syzygies. The radial pinnules are very large and massive, the first one especially so. It consists of twenty or twenty-two joints, the first six of which are very stout and almost cubical in appearance, the second being the largest, and the terminal joints slightly serrate, 368 THE VOYAGE OF H.M.S. CHALLENGER. The following pinnules gradually decrease in size and their jomts become more flattened, the two lowest retaining a certain amount of preponderance, being often much broader than their successors. Beyond the distichal axillary, however, this is almost entirely lost, the pinnules tapering gradually and symmetrically from the basal joints, which are not specially distinguished in any way. The disk (so far as it is visible) is covered with numerous small plates which are not, however, set perfectly close to one another. Brachial ambulacra but little above the arm-grooves, and bordered by somewhat forked plates from which the large side plates of the pinnule-ambulacra are soon developed. Colour in spirit, greyish-white, with a tinge of brown at the tips of the cirri, arms, and pinnules. Locality.—Station 209, January 22, 1875; lat. 10° 14’ N., long. 123° 54’ E.; 95 fathoms; blue mud; bottom temperature, 71° F. One specimen. Remarks.—This species is readily distinguished from the three preceding ones in the same group by the greater length of the internodes in the stem. Their component joints (Pl. LIL. fig. 3) are altogether different from the lobate joints of Metacrinus costatus (Pl. XLIX. fig. 4) and of Metacrinus nodosus (Pl. LI. fig. 10), having the same pentagonal form and horizontal ridges as Metacrinus wyvillii (Pl. XLVI. fig. 4). The nodal and infra-nodal joints, however, are entirely different from those of this type, in which the infra-nodals are distinctly incised by the cirrus-sockets, so that their syzygial surface is lobate (Pl. XLVII. fig. 3) and not pentagonal as in Metacrinus interruptus. Another character in which this species differs very markedly from the three previously considered is the small size of the basal jomts on the palmar and lower brachial pinnules. The type to which on the whole Metacrinus interruptus appears to be most closely allied is the as yet undescribed specimen dredged by the “Vega” at a depth of 65 fathoms in the Bay of Yedo. By the kind permission of Prof. 8. Lovén, who was good enough to send me some fragments of its stem, and also to allow my friend Mr. W. Percy Sladen to examine it on my behalf, I am able to say that it appears to be totally different from Metacrinus interruptus. The stem-joints that I have seen have a smaller diameter and a greater height both relatively and absolutely than those of that species; and they are not provided with horizontal ridges, but only with faint tubercles at the angles, and still less distinct ones at the sides. In the character of the nodal joints, however, and in the absence of any extension of the cirrus-socket down on to the infra-nodals, the two types are very closely similar, as they are in the length of the internodes. There seem to be several other points of difference between Metacrinus interruptus and the “ Vega” specimen, such, for example, as the length of the primary arms and the characters of the pinnules. These will doubtless be explained more fully when the “ Vega” Crinoids are described - and I have therefore done no more than assign to the Japanese form a place REPORT ON THE CRINOIDEA. 369 in the tabular key to the species which embraces all the types of this genus that have yet been discovered. The individual described above is the only specimen of any kind of Crinoid which was obtained at Station 209; and it has fortunately suffered much less injury than many of the larger types dredged by the Challenger. I did not succeed in finding any Myzostoma upon it; but a Scalpellwm is attached to its stem, and several individuals of Verruca to the cirri, on one of which a small Avicula was fixed by its byssus. 11. Metacrinus tuberosus, n. sp. (Pl. LIII. figs. 1-6). Three species (Metacrinus angulatus, Metacrinus nobilis, Metacrinus cingulatus), repre- were dredged by the Challenger at Station 192, off the Ki Islands. Together with these there came up a fragment of a stem which I cannot 1 sented by “about a dozen individuals, refer to either of these species, nor to any other Metacrinus yet known. It presents a curious combination of certain features which are characteristic of the stems of Metacrinus. angulatus, Metacrinus costatus, and Metacrinus nobilis respectively, three very distinct species from widely separated localities on different sides of the equator (Ki, Meangis, and Kermadec Islands). I have no hesitation in regarding it as belonging to another species of the genus, although the characters of its calyx are as yet unknown. It cannot belong to a Pentacrinus on account of the upward extension of the cirrus- sockets on to the supra-nodal joints (PI. LIII. fig. 2), a character which is eminently distinctive of Metacrinus. The fragment consisted of five complete internodes, one of which was sacrificed to anatomical purposes, so that only four are shown in the figure (Pl. LUI. fig. 1). Hach internode consists of seven slightly crenulated joints. The five middle ones are as usual different from those immediately above and below the nodes. They are sharply pentagonal in form, with a somewhat prominent tubercle in the middle of each side (Pl. LIII. figs. 4, 6); while the angles are sharp and slightly produced outwards beyond the ends of the petaloid areas, as is to some extent the case in Metacrinus angulatus and Metacrinus costatus (Pl. XXXIX. figs. 3, 8,10, 11; Pl. XLIX. figs. 3, 4). This is still more evident in the nodal joints (Pl. LIII. fig. 3) as it also is in the other two species (Pl. XXXIX. figs. 3-5; Pl. XLIX. fig. 5), and more distinctly in Metacrinus nodosus, the internodes of which are not specially produced at the angles (PI. LI. figs. 8-10). The consequence is that the stem of Metacrinus tuberosus, like that of Metacrinus angulatus and Metacrinus costatus, is traversed by prominent interradial ridges (Pl, XCXVIE EPOX XMIX. figs, 3) 00: PES RLIX. figs. 1,.3; PL. DIT figs. 196). The nodal joimts have somewhat deeply hollowed cirrus-sockets which have relatively wide facets, and encroach both on the supra- (Pl. LIII. fig. 2) and on the infra-nodal 1 See R. v. Willemoes Suhm, Briefe von der Challenger Expedition, No. iv., Zeitschr. f. wiss. Zool., Bd. xvi. p. liil., 1876. (ZOOL. CHALL, EXP.— PART XxxIt.—1884.) Ii 47 370 THE VOYAGE OF H.M.S. CHALLENGER. joints (Pl. LIII. fig. 5); so that their re-entering angles are deeper than those of the remaining internodal joints (Pl. LUI. fig. 4). On both of these, but especially on the infra-nodal (fig. 5), the single tubercles at the sides of the joint are more or less double, and enlarged into a horizontal ridge. A peculiarity of somewhat the same kind occurs in Metacrinus costatus (Pl. XLIX. fig. 3). The cirri are about 35 mm. long, and closely resemble those of other species of the genus. They consist of some forty uniformly squarish joints, the basal ones of which are not much wider than their successors, though projecting a little beyond them on the dorsal side. There is no trace of interarticular pores, so that this fragment cannot have come from near the top of the stem. Thus, then, the peculiarities of this stem-fragment are sufficiently characteristic to indicate that it belongs to a different species of Metacrinus from any of those described above. In the prominence of the angles of the nodal joints, and in the presence of tubercles along the sides of the internodes, it resembles Metacrinus nodosus (P1. LI. fig. 8). But in the sharpness of the ridges formed by the angles of the internodes it approaches Metacrinus angulatus (Pl. XXXIX. figs. 3, 11) and Metacrinus costatus (Pl. XLIX. figs. 1, 2). As the composition of its calyx is unknown, no place can be assigned to Metacrinus tuberosus in the tabular scheme of the genus. If there be four radials it would come near Metacrinus angulatus, though the internodes are shorter than in this type; but if the number of radials be six, its place would be next to Metacrinus costatus and Metacrinus noddsus, both of which it resembles in the length of its internodes. Clinging to this stem by its long arms was the pluteus-larva of an Ophiurid, with three arm plates beyond the disk. Locality.—Station 192, September 26, 1874; in the Arafura Sea, near the Ki Islands; lat. 5° 49’ 8., long. 182° 14’ E.; 140 fathoms; blue mud. A stem-fragment only. Family ComatuLip&, d’Orbigny, 1852. Genus Thaumatocrinus, P. H. Carpenter, 1883. Thaumatocrinus, P. H. Carpenter, Phil, Trans., part iii, 1883, p. 919, pl. 71. Definition. radials, the latter resting on the basals and so separating the radials laterally. That Calyx composed of a centro-dorsal, basals, radials, and primary inter- on the anal side bears a short jointed appendage. Mouth central, and protected by five large oral plates which occupy the greater part of the disk, and are separated from the calyx interradials by two or three rows of small irregular plates. Five arms only. Remarks.—Although this very singular genus is a true Comatula, 1.e., provided with a centro-dorsal plate or cirrus-bearing top stem-joint which separates it from the remainder Sad iad REPORT ON THE. CRINOIDEA. 371 of the larval stem, I have preferred to describe it in the same part of the Crinoid Report as the Stalked Crinoids. For it is only among certain of the Paleocrinoidea that we meet with characters which are at all like the more striking pecularities of. Thaumatocrinus. There can, I think, be no doubt that the large and comparatively dense oral plates are not in a state of resorption as they are in other Comatuls of the same size ; for they have all the appearance of being permanent structures. Thaumatocrinus is therefore the only Comatula yet known in which the oral plates of the larva persist through life as in Hyocrinus and Rhizocrinus. Another striking peculiarity is presented by the closed ring of relatively large basals which have remained in their primitive position upon the exterior of the calyx and have not undergone transformation into a rosette, as is the case in most other Comatule.. The only other recent type in which the basals remain visible on the exterior of the calyx is the curious genus Atelecrinus ; 1 and here they are very small in proportion to the radials. This is probably also the case in the Cretaceous species which is mentioned by Schliiter * as provided with a closed basal ring. Both the persistence of the basals and the considerable development of the orals are characters which, either singly or combined, would cause the type to be regarded as one of no little interest; but they are altogether cast into the shade by the other peculiarities of the calyx, viz., the complete separation of the radials by relatively large interradial plates and the presence of the anal appendage. It has been shown elsewhere ® that in the separation of its radials laterally Thawmatocrinus is permanently in the condition of ‘4 Crinoid larva at a very early period of Pentacrinoid life, and that this condition is characteristic of certain Paleeocrinoids belonging to the family Rhodocrinide. Some genera, such as the Lower Silurian Reteocrinus and Xenocrinus, have the radials separated by what Messrs. Wachsmuth and Springer * describe as an “interradial series resting directly upon the basals, consisting of a very large number of minute pieces of irregular form, and without definite arrangement.” A similar development of small irregular plates between the rays occur in many Neocrinoids, both stalked and free, but the interradial series always commence at the level of the second or third radials, and are completely separated from the basals by the ring of united first radials. This is well seen in Pentacrinus asterius (Pl. XIIL fig. 1) and in the fossil Extracrinus. In other genera of the Rhodocrinidie such as Rhodocrinus itself, Thylacocrinus, and others forming the section Rhodocrinites, the first radials are separated not by small and irregular plates as in Reteocrinus, but by large plates, one resting on a basal in each interradius; and this is the condition of 7 haumatocrinus (Pl. LVI. figs. 1-4). While 1 Bull. Mus. Comp. Zobl., vol. ix., No. 4, 1881, p. 16, pl. i. figs. 1-7. 2 Zeitschr. d. deutsch. geol. Gesellsch., Jahrg. 1878, p. 66. 3 Phil. Trans., 1883, part iii. pp. 923-926 ; and ante, pp. 39, 40. 4 Revision, part ii. p. 192. 372 THE VOYAGE OF H.M.S. CHALLENGER. resembling the Fhodocrinites in having five large plates separating the radials, Thaumatocrinus differs from them and from most Palzocrinoids in the absence of any - higher series of calicular interradial plates resting upon the first series which separate the radials. Except on the anal side the primary,interradial plates of Thawmatocrinus end simply in a free rounded edge at the margin of the disk (Pl. LVI. figs. 1-3, 5), which is doubtless due to the simplicity of the arms; for these become free almost at once, and are not connected laterally by much perisome in which higher orders of radials could be supported. But in the presence of the anal appendage on the azygous interradial (Pl. LVI. figs. 2, 4, 5) Thaumatocrinus bears a remarkable resemblance to Reteocrinus as understood by Wachsmuth and Springer, and to the Xenocrinus of 8. A. Miller; while the appendage has an even closer resemblance to the so called “anal series” of Onychocrinus and Taxocrinus, the lowest plate of which rests, not on a basal, but on the upper angles of the two first radials. There can, I think, be no reasonable doubt that the anal appendage of Thawmato- erinus, although free laterally, is homologous with the vertical series of plates in the anal interradius of Reteocrinus and Xenocrinus, Onychocrinus and Taxocrinus. But owing to the small size of Thawmatocrinus and the simplicity of its rays the anal appendage is free ; whereas in the Palzeocrinoids it is united to the more or less branching rays by the general series of minute irregular plates which occupy the anal interradius and pass gradually upwards into those of the so called vault. It is difficult to consider the existence of interradials and of the anal appendage of Thaumatocrinus as instances of atavism, for no known Neocrinoid presents any similar ” characters, and it is a long way back from a recent Comatula to a Paleozoic Crinoid. The reappearance of these characters in such a specialised type as a Comatula is conse- quently not a little surprising. Associated with them we find the distinctly embryonic characters of persistent basal and oral plates, the latter occurring in no other Comatula, together with the simplicity of the undivided arms. Thaumatocrinus renovatus, P. H. Carpenter, 1883 (Pl. LVI. figs. 1-5). Description of an Individual.—The total width of the calyx across the disk is barely 2mm.; and the height of the centro-dorsal and radials together is about the same. The former (Pl. LVI. figs. 1-4) is rounded below, with its central canal completely closed up, so that it must have been detached for some little time from the remainder of the stem. The bases of half a dozen cirri are attached to it, and there are pits for the reception of two or three more. In the largest stump which is preserved (Pl. LVI. figs. 1, 3) the first two joints are quite short, as is usually the case in all cirri; but the third reaches a length of 1°5 mm., so that the cirri must have been very like those of REPORT ON THE CRINOIDEA. 373 some species of Hudiocrinus which have a succession of very long joints following the short basal ones. The basals are almost trapezoidal, much wider below than above, and in contact with one another by their truncated lower angles (Pl. LVI. figs. 1, 2). The middle of the lower edge of each is slightly tubercular. On their narrow upper edges rest the interradials, which are oblong and a little higher than wide. Four of them terminate in a free edge at the margin of the disk where they are in contact with the lowest anambulacral plates. But that on the anal side bears a small tapering appendage of four or five joints, the last of which seems to end freely (Pl. LVI. figs. 2, 4, 5). The radials are larger than the interradials, and somewhat strongly arched. There is a muscular articulation between them and the first brachials; but the union of these to the next joints appears to be by ligament only. The arm-joints are long, slender, and cylindrical. One arm seems to be broken at the syzygy in the sixth brachial; while another has a syzygy in the fourth and again in the eighth brachial. The second brachial bears the first pinnule, which is on the right side in three arms and on the left in the other two. The pinnules are very delicate, and composed of long slender joints. The central portion of the disk is occupied by five relatively large oral plates which stand up around the peristome (Pl. LVI. fig. 5); while between them and the margin are two or three irregular rows of small anambulacral plates, some of them extending up on to the lower part of the long anal tube. The brachial ambulacra are not plated, however, and he in the arm-grooves, close down between the muscles, but with no traces of sacculi. Colour in spirit, dirty white. Locality.—Station 158, March 7, 1874; lat. 50° 1’S., long. 123° 4’ E.; 1800 fathoms ; Globigerina ooze; bottom temperature, 33°°5 F. One specimen much mutilated and probably young. 374 THE VOYAGE OF H.M.S. CHALLENGER. XIII.—BATHYMETRICAL DISTRIBUTION AND STATION LISTS. Station List OF THE STALKED CRINOIDS WHICH HAVE BEEN OBTAINED BY THE VARIOUS British EXPEDITIONS FoR DrEEP-SEA EXPLORATION BETWEEN THE YEARS 1868 AND 1880. This list also contains the names of the rarer Comatulee, when dredged at a Station where Stalked Crinoids occurred. The presence of the more common genera (Antedon and Actinometra) is also indicated, though without any attempt to go into specific details. H.M.S. “ Licutnine,” 1868. Sration 12. Lat. 59° 36’ N., long. 7° 20’ W.; 530 fathoms; Globigerina ooze ; bottom temperature, 47°'3 F. Rhizocrinus lofotensis. Station 16. Lat. 61° 2’ N., long. 12° 4’ W.; 650 fathoms ; Globigerina ooze. Rhizocrinus lofotensis. Also at Station 12; and the “Knight Errant,” 1880, Stations 5 and 6; the Challenger, Stations 244, 122c, and 323 (fide C. W. T.). Also at several Stations in the Gulf Stream, the Carib- bean Sea, and off the New England coast. H.M.S. “ Porcupine,” 1869. Station 37. Lat. 47° 38’ N., long. 12° 8’ W.; 2435 fathoms ; Globigerina ooze ; bottom temperature, 36°°5 F. Bathycrinus gracilis. Also the “Talisman” (1883), off the Morocco coast—“ Par le travers du cap Ghir et du cap Noun & 120 milles environ de la céte,” 2000-2300 metres (about 1200 fathoms). Station 42. Lat. 49° 12’N., long. 12° 52’ W.; 862 fathoms ; ooze with sand and shells ; bottom temperature, 39°-7 F. Rhizocrinus rawsoni. REPORT ON THE CRINOIDEA. 375 Sration 43. Lat. 50° 1’ N., long. 12° 26’ W.; 1207 fathoms; Globigerina ooze ; bottom temperature, 37°°7 F, Rhizocrinus rawson. Also at Station 42 ; the Challenger, Station 76; and at various Stations in the Caribbean Sea. Also the “ Travailleur” (1882)—‘ 1900m. de pro- fondeur sur les cétes du Maroc, par le travers du cap Blanc ;” and the “Talisman” (1883)—“ Par le travers du cap Ghir et du cap Noun 4 120 milles environ de la céte,” 2000-2300 metres (about 1200 fathoms). HLM.S. “ PORCUPINE,” 1870. Sration 17. Lat. 39° 42’ N., long. 9° 43’ W.; 1095 fathoms; ooze; bottom temperature, S507 i Pentacrinus wyville-thomsoni. Also the “Talisman” (1883); off the Morocco coast: and again off Rochefort; lat. 45° 59’ N., long. 6° 29’ W. of Paris; 1500 metres (800 fathoms). H.M.S. “ Knigut Errant,” 1880. Sratron 5. Lat. 59° 26’ N., long. 7° 19’ W.; 515 fathoms; mud; bottom temperature, ApeAy ih, Rhizocrinus lofotensis. Station 6. Lat. 59° 37’ N., long. 7° 19° W.; 530 fathoms; grey mud; bottom temperature, 46°°5 F. Rhizocrinus lofotensis. H.M.S. CHALLENGER, 1873-76. Sration 244. March 25, 1873; off Culebra Island; lat. 18° 43’ N., long. 65° 5’ W.; 625 fathoms ; Pteropod ooze. Rhizocrinus lofotensis. Also Stations 122c and 323 (fide C. W.T.) ; the “Lightning” (1868), Stations 12 and 16; and the “Knight Errant” (1880), Stations 5 and 6. Several Stations in the Gulf Stream, the Caribbean Sea, and off the New England coast. 376 THE VOYAGE OF H.M.S. CHALLENGER. Sration 76. July 3, 1873; south of Terceira (Azores) ; lat. 38° 11’ N., long. 27° 9’ W. ; 900 fathoms; Pteropod ooze ; bottom temperature, 40° F. Rhizocrinus rawsoni. Also the “ Porcupine” (1869), Stations 42 and 43. Also. the ‘“Travailleur” (1882), the “Talisman” (1883), and at several Stations in the Caribbean Sea. StaTion 106. August 25, 1873; lat. 1° 47’ N., long. 24° 26’ W.; 1850 fathoms; Globigerina ooze ; bottom temperature, 36°°6 F. Bathycrinus campbellianus. Hyocrinus bethellianus (stem-fragments, fide C. W. T.). Also at Station 147; and Station 223 ? Station 122. September 10, 1873; off Barra Grande; lat. 9° 5’ S., long. 34° 50’ W.; 350 fathoms ; red mud. Pentacrinus maclearanus. Atelecrinus balanoides. Also at several Stations in the Caribbean Sea. Station 122c. September 10, 1873; off Barra Grande ; lat. 9° 10’ S., long. 34° 49’ W. ; 400 fathoms; red mud. Rhizocrinus lofotensis. Also Stations 244 and 328 (fide C. W. T.); the “ Lightning” (1868), Stations 12 and 16; and the “Knight Errant” (1880), Stations 5 and 6. Several Stations in the Gulf Stream, the Carib- bean Sea, and off the New England coast. Station 146. December 29, 1873; lat. 46° 46’ S., long. 45° 31’ E.; 1375 fathoms; Globigerina ooze ; bottom temperature, 36°°6 F. Bathycrinus aldrichianus. Also at Station 147 ; and “at at least six or seven Stations in the Atlantic and the Southern Ocean.” Station 147. December 30, 1873; lat. 46° 16’S., long. 48° 27’ E.; 1600 fathoms ; Diatom ooze ; bottom temperature, 34°:2 F. Bathycrinus aldrichianus. Also at Station 146. Fyocrinus bethellianus. Also at Stations 106 and 223 (fide CWA): Antedon (three species). , Promachocrinus abyssorum. Also at Station 158. REPORT ON THE CRINOIDEA. 377 Station 158. March 7, 1874; lat. 50° 1’ S., long. 123° 4’ E.; 1800 fathoms; Globi- gerina ooze; bottom temperature, 33°°5 F. Thaumatocrinus renovatus. Promachocrinus abyssorum. Also at Station 147. Sration 170a. July 14, 1874; near the Kermadec Islands; lat. 29° 45’ S., long. 178° 11’ W.; 630 fathoms; volcanic mud; bottom temperature, 39°°5 F. Pentacrinus naresianus. Also at Stations 171, 175, 210 (?), 214. Metacrinus nodosus Metacrinus wyvilli. Also at Station 214. Antedon (six species). Sration 171. July 15, 1874; off Raoul Island; lat. 28° 33’ S., long. 177° 50’ W.; 600 fathoms ; hard ground ; bottom temperature, 39°°5 F. Pentacrinus alternicirrus. Also at Stations 210 (?), 214. Pentacrinus naresianus. Also at Stations 170A, 175, 210 (2), 214. Sration 175. August 12, 1874; near Kandavu, Fiji; lat. 19° 2’ S., long. 177° 10’ E.; 1350 fathoms; Globigerina ooze ; bottom temperature, 36°08. Pentacrinus naresianus. Also at Stations 170A, 171, 210 (2), 214. Antedon (three species). Sration 192. September 26, 1874; near the Ki Islands; lat. 5° 49’ 8S. long. 132° 14’E.; 140 fathoms; blue mud. Metacrinus angulatus. Metacrinus cingulatus. Metacrinus murrayi (?). Metacrinus nobilis. Metacrinus tuberosus. Antedon (twelve species). Actinometra (one species). SraTion 209. January 22, 1875; lat. 10° 14’ N., long. 123° 54’ E.; 95 fathoms; blue mud; bottom temperature, 71° F. Metacrinus interruptus. (ZOOL, CHALL. EXP.—PART Xxxi1.—1884.) Ti 48 378 THE VOYAGE OF H.M.S. CHALLENGER. Station 210. January 25, 1875; off the Panglao and Siquijor Islands; lat. 9° 26’ N., long. 123° 45’ E.; 875 fathoms; blue mud; bottom temperature, 54°°1 F. Pentacrinus alternicirrus (?). Also at Stations 171 and 214. Pentacrinus naresianus(?). Also at Stations 1704,171,175, and 214. Metacrinus murrayi (2). Antedon (two species). STATION 214. February 10, 1875; off the Meangis Islands; lat. 4° 33’ N., long. 127° 6’ E.; 500 fathoms ; blue mud ; bottom temperature, 41°°8 F, Pentacrinus alternicirrus. Also at Stations 171 and 210 (2). Pentacrinus naresianus. Also at Stations 170A, 171, 175, and 210 (2). Metacrinus costatus. Metacrinus moseleyi. Metacrinus murrayi (2). Metacrinus varians. Metacrinus wyvilli. Also at Station 170a. Antedon (six species). Promachocrinus naresi. STaTIon 223. . March 19, 1875; lat. 5° 31’ N., long. 145° 13’ E. ; 2325 fathoms; Globigerina ooze ; bottom temperature, 35°°5 F. Hyocrinus bethellianus, young (fide C. W.T.). Also at Stations 106 (C. W. T.) and 147. Sravion 235. June 4, 1875; lat. 34° 7’ N., long. 138° 0’ E.; 565 fathoms; green mud ; \ bottom temperature, 38°°1 F. Pentacrinus (?) mollis. Eudiocrinus japonicus. SraTIon 323. February 28, 1876; lat. 35° 39’ S., long. 50° 47’ W.; 1900 fathoms ; blue mud ; bottom temperature, 33°71 F. Rhizocrinus lofotensis (fide C.W.T.). Also the “ Lightning” (1868), Stations 12 and 16; the “ Knight Errant ” (1880), Stations 5 and 6; and the Challenger, Stations 24a and 122c. Also at several Stations in the Gulf Stream, the Caribbean Sea, and off the New England coast. pals REPORT ON THE CRINOIDEA. 379 Station List OF THE STALKED CRINOIDS WHICH HAVE BEEN OBTAINED BY THE VARIOUS AMERICAN EXPEDITIONS FoR DrEp-Sea EXPLORATION (MOSTLY UNDER THE DIRECTION oF Mr. ALEXANDER AGASSIZ) BETWEEN THE YEARS 1867 AND 1880. The presence of Comatulze is noticed as in the previous list ; but the occurrence of a species at several Stations is not, as a rule, recorded more than once. SS. ‘ Corwin,” 1867. No, 2. May 24, 1867; 1°6 miles from Chorrera, Cuba ; 270 fathoms. Pentacrinus decorus (stem only *). SS. “Brpp,” 1868-69. May 9,1868; off the Samboes ; 237 fathoms. May 11, 1868; off Sand Key ; 248 and 306 fathoms. Rhizocrinus lofotensis. Also off Havana, Barbados, Grenada, and Grenadines. Dredged by the “ Lightning,” the Challenger, and the “ Knight Errant.” March 4, 1869; off Cojima, near Havana; 450 fathoms. Rhizocrinus lofotensis. Atelecrinus cubensis. Antedon. March 10, 1869 ; off Double-headed Shot Keys ; 315 and 471 (?) fathoms. Pentacrinus decorus (stem only ?). SS. “ HasstEr,” 1871-72. December 30, E71, 70 Sandy Bay, Barbados; 100 fathoms. Rhizocrinus rawsom. Also off Havana, Montserrat, Guadeloupe, Dominica, Martinique, and Panama. Dredged in ' the East Atlantic by the ‘“ Porcupine,” Challenger, Talisman,” and “ Travailleur.” SS. ‘‘ BLaKe,” 1878-80. Cruise of 1877-78. Stratton 21. Off Bahia Honda, Cuba; lat. 23° 2’ N., long. 83° 18’ W. ; 287 fathoms. Pentacrinus decorus. Also off Havana, Montserrat, St. Vincent Barbados, Kingston, and Saba Island. 380 STATION 22. STATION 29. STATION 32. STaTIon 35. Station 43. STATION 44, STATION 56. STATION 57. STATION 100. THE VOYAGE OF H.M.S. CHALLENGER. Off Bahia Honda, Cuba; lat. 23° 1’ N., long. 83° 14’ W.; 100 fathoms ; bottom temperature, 71° F. Holopus rangi. Also off Barbados (Rawson) and Montserrat. ° Lat. 24° 36’ N., long. 84° 5’ W.; 955 fathoms; bottom temperature, 393° F. Rhizocrinus lofotensis. Lat. 23° 32’ N., long. 88° 5’ W.; 95 fathoms. Rhizocrinus rawsoni. Antedon. Lat. 23° 52’ N., long. 88° 58’ W.; 804 fathoms; bottom temperature, 404° F, Rhizocrinus lofotensis. Lat 24° 8’ N., long. 82° 51’ W.; 339 fathoms. Rhizocrinus lofotensis. Atelecrinus balanoides. Lat. 25° 33’ N., long. 84° 35’ W.; 539 fathoms; bottom temperature, 394° F, oo Rhizocrinus lofotensis. Off Havana ; lat. 22° 9’ N., long: 82° 21’ 30” W.; 175 fathoms. Rhizocrinus lofotensis. Pentacrinus decorus. a Pentacrinus miilleri. Also off Santiago de Cuba, Barbados, ‘ Guadeloupe, Martinique, St. Lucia, St. Vincent, Montserrat, Saba Island. % Antedon. Off Havana ; lat. 22° 9’ 15” N., long. 82° 21’ W.; 177 fathoms. Pentacrinus decorus. Antedon. Cruise of 1878-79. Off Morro Light ; 250 and 400 fathoms. Pentacrinus decorus. Pentacrinus miilleri. REPORT ON THE CRINOIDEA. 381 Station 101. Off Morro Light; 175 and 250 fathoms. Pentacrinus decorus. Pentacrinus miilleri. Antedon. Sration 155. Off Montserrat; 88 fathoms; bottom temperature, 69° F. Rhizocrinus rawsoni. Pentacrinus decorus. Antedon. Actinometra. Sration 156. Off Montserrat; 88 fathoms; bottom temperature, 69° F. Pentacrinus decorus. Antedon. Actinometra. Sration 157. Off Montserrat ; 120 fathoms. Holopus rangi. Also off Barbados(Rawson) and Bahia Honda(Cuba). Pentacrinus asterius. Also off Saba Island. Pentacrinus blakei. Also off Barbados and Martinique. Pentacrinus decorus. Pentacrinus miilleri. Antedon. Actinometra. Sration 166. Off Guadeloupe; 150 fathoms; hard bottom; bottom temperature, 592° F. Rhizocrinus rawsoni. Sration 171. . Off Guadeloupe ; 183 fathoms; bottom temperature, 554° F. Pentacrinus miilleri. Actinometra. Station 177. Off Dominica; 118 fathoms; fine sand and broken shells; bottom temperature, 65° F. Rhizocrinus rawsont. Actinometra. Sratron 193. Off Martinique; 169 fathoms; fine sand, dark mud, and shells; bottom temperature, 51° F. Pentaerinus miilleri. Antedon. Actinometra. 382 STATION 209. STATION 211. STATION 218. - STATION 233. STATION 238. STATION 248. STATION 259. STATION 269. Station 273. - THE VOYAGE OF H.M.S8. CHALLENGER. Off Martinique ; 189 fathoms; bottom temperature, 492° F. Pentacrinus blaket. Also of Barbados and Montserrat. Off Martinique ; 357 fathoms; fine yellow sand and broken shells. Rhizocrinus rawsoni. Off St. Lucia; 164 fathoms; bottom temperature, 56° F. Pentacrinus miilleri. Off Milligan’s Key, St. Vincent; 174 fathoms; rocky bottom; bottom temperature, 493° F. Pentacrinus decorus. Antedon. Off Grenadines ; 127 fathoms; fine coral sand ; bottom temperature, 56° F.) Rhizocrinus lofotensis. Off Grenada; 161 fathoms; fine grey ooze; bottom temperature, 533° F. Rhizocrinus lofotensis. Actinometra. Off Grenada; 159 fathoms; bottom temperature, 534° F. Rhizocrinus lofotensis. Antedon, Actinometra. Off St. Vincent ; 124 fathoms; bottom temperature, 573° F. _ Pentacrinus decorus. Pentacrinus miilleri. Antedon. Actinometra. Off Barbados; 103 fathoms; coral and broken shell, yellow; bottom temperature, 594° F. Rhizocrinus rawsoni. Actinometra. Sration 274. Off Barbados; 209 fathoms; fine sand and ooze; bottom temperature, = 534° F. Rhizocrinus lofotensis. Pentacrinus miilleri. REPORT ON THE CRINOIDEA. 385 Sration 277. Off. Barbados; 106 fathoms; hard rocky bottom; bottom temperature, 58° F.) Rhizocrinus rawsoni. Actinometra. Sration 280. Off Barbados; 221 fathoms; Globigerina sand; bottom temperature, 503° F. Pentacrinus miilleri. - - Sration 283. Off Barbados ; 237 fathoms; hard bottom ; bottom temperature, 49° F. Pentacrinus miilleri. Antedon. ‘ Sration 290. Off Barbados ; 73 fathoms ; coarse coral sand and broken shells ; bottom temperature, 703° F. Rhizocrinus rawsoni. Antedon. Actinometra. Sration 291.. Off Barbados; 200 fathoms; flat calcareous stones ; bottom temperature, 493° F, | Pentacrinus blakei, Also off Martinique and Montserrat. Pentacrinus miillert. SS Sration 295. Off Barbados; 180 fathoms ; hard bottom ; bottom temperature, 505° F. ; Pentacrinus blakei. Pentacrinus miilleri. Sration 296. Off Barbados ; 84 fathoms; hard bottom ; bottom temperature, 614° F. Rhizocrinus rawsoni. Pentacrinus decorus. Pentacrinus miilleri. Actinometra. Sration 297. Off Barbados; 123 fathoms; calcareous stones; bottom temperature, é 564° F. ‘ Rhizocrinus rawsoni. Antedon. Actinometra. 384 THE VOYAGE OF H.M.S. CHALLENGER. Station 298. Off Barbados; 120 fathoms; broken shells and coral; bottom tempera- ture, 61° F, ; Pentacrinus decorus. . Antedon. Actinometra. Station V. Santiago de Cuba; 288 fathoms. Pentacrinus decorus. © Cruise of 1879-80. Off Kingston (Jamaica); 100 fathoms. Pentacrinus decorus. Station 306. Lat. 41° 32’ N., long. 65° 55’ W.; 524 fathoms. Rhizocrinus lofotensis. OTHER LOCALITIES IN THE CARIBBEAN SEA, THE GuLF oF Mexico, AND IN THE ATLANTIC OCEAN. U. 8. Fish Commission, 1882. No. 1124, 8.S.E. off Nantucket ; 640 fathoms. Rhizocrinus lofotensis. SS. “Investigator,” Captain E. Cole. Saba Bank; 200 fathoms. Rhizocrinus rawsoni. Saba Island ; 320 fathoms. Pentacrinus asterius. Pentacrinus decorus. Between Saba and Eustatius Islands; 531 fathoms. Pentacrinus miilleri. Pentacrinus decorus. Fifteen miles N.E. from Panama; 300 fathoms. Rhizocrinus rawsont. South side of Porto Rico; 667 fathoms. Pentacrinus decorus. Dr W. REPORT ON THE CRINOIDEA. 385 . Schramm, Guadeloupe. 4, os Pentacrinus asterius. Stimpson, Cuba. Pentacrinus decorus. Sir Rawson Rawson, Barbados. f Pentacrinus miillera. Pentacrinus decorus. * | Antedon. Actinometra. Be Holopus rangi. A List oF THE KNOWN Lavina Species oF STALKED CRINOIDS, SHOWING THEIR BATHYMETRICAL AND GEOGRAPHICAL DISTRIBUTION. Explanation of the Letters used. Species discovered by the “ Blake.” Previously known species collected by the “Blake” and the U. S. Coast Survey Expeditions. Species discovered by the Challenger. . Previously known species collected by the Challenger. Species discovered by the ships of the Eastern Telegraph Company. Species discovered by Dr. L. Déderlein. Previously known species collected by the telegraph steamer “ Investigator,” Captain E. Cole. Previously known species collected by the “ Josephine ” (Swedish). . Species discovered by the “ Véringen” (Norwegian). Species discovered by the “ Porcupine.” Previously known species collected by the “ Lightning,” “ Porcupine,” and “ Knight Errant.” Previously known species collected for Sir Rawson Rawson. Previously known species collected by the “ Talisman” and “ Travailleur” (French). Species discovered by the “ Vega” (Swedish). . Species discovered by Mr. Damon’s collectors. Previously known species obtained by Mr. Damon's collectors. (ZOOL. CHALL. EXP.—PART XXxi1,—1884.) li 49 386 THE VOYAGE OF H.M.S. CHALLENGER. How Range in ube ae dainans Depth, Principal Localities. Fathoms. Hoxorrp2, Roemer, Holopus, VOrb., H. rangi, VOrb., —. : ; B. R. 100-120 | Caribbean Islands. Hyocrtnip&, Carpenter, Hyocrinus, Wyv. Thoms., . F ae ie +8 HZ. bethellianus, Wyv. Thoms., . C. 1600-1850} Mid-Atlantic, Station 106 (stem-fragments) ; 23251 Southern Ocean, Station 147; East Pacific, Station 223 (young 2). BourGvueEticrinip#, de Loriol, Bathycrinus, Wyv. Thoms., B. aldrichianus, Wyv. Thoms.,. C. 1375-1600| Southern Ocean, Stations 146, 147. B. campbellianus, Carp., . ; C. 1850 Mid-Atlantic, Station 106. B. carpenteri, Dan. & Kor., WE 1050-1495 | North-East Atlantic. B. gracilis, Wyv. Thoms., Pie Wiper cee bs 1280-2435] East Atlantic. Rhizocrinus, Sars, R. lofotensis, Sars, . ; . | B.D. J. Q.| 80-955 | Lofoten Islands; Farde Channel; North-East 1900? Atlantic ; Josephine Bank. Atlantic Coast of U.S. (Northern States) ; Straits of Florida; | Caribbean Islands; South-West Atlantic, Station 1220 and Station 323 (2). R. rawsoni, Pourt., . PP AD Ie 73-1280 | East Atlantic, Station 76; Straits of Florida ; 1 ead be Caribbean Islands; Yucatan Bank; off Panama. PENTACRINIDS, d’Orb., Pentacrinus, Miller, P. alternicirrus, Carp., —. : C. 500-600 | Pacific—near the Kermadecs, Station 171; and 3752 near the Meangis Islands, Station 214; off the Panglao and Siquijor Islands, Station 210 (2). P. asterius, Linn., . : ai RG Ye 80-320 | Caribbean Islands. P. blakei, Carp., : : A. 120-200 | Caribbean Islands. P. decorus, Wyv. Thoms., 25 SB le xX 84-667 | Caribbean Islands,; Straits of Florida. REPORT ON P, maclearanus, Wyv. Thoms., P. mollis, Carp., P. miilleri, Oerst., P. naresianus, Carp., P. wyville-thomsoni, Jeffr., Metacrinus, Carp., M. angulatus, Carp., M, cingulatus, Carp., M. costatus, Carp., WM. interruptus, Carp., M. moseleyt, Carp., . M. murrayi, Carp., - M. nobilis, Carp., WM. nodosus, Carp., . M. rotundus, Carp., M. stewarti, Carp., . M. superbus, Carp., . M. tuberosus, Carp., M. varians, Carp., M. wyvillii, Carp., Metacrinus, sp., How obtained. Bae Ry Ye BR BOO Oe OO fa. oe Q = THE CRINOIDEA. 387 ets Principal Localities. Fathoms. 350 South-West Atlantic, Station 122. 565 North-West Pacific. 84-531 | Caribbean Islands; Straits of Florida. 500-1350 | Pacific—nearthe Kermadecs, Stations 170, 170, 375? 171; near Fiji, Station 175; and near the Meangis Islands, Station 214; off the Panglao and Siquijor Islands, Station 210 (#). 740-1095 | East Atlantic. 140 Ki Islands, Station 192. 140 Ki Islands, Station 192. 500 Pacitic, near the Meangis Islands, Station 294. 95 Philippine Islands, Station 209. 500 Pacific, near the Meangis Islands, Station 214. q Western Pacific, or East Indian Archipelago. 140 Ki Islands, Station 192. 630 Pacific, near the Kermadecs, Station 170a. 70 Japan. q Singapore. q Singapore. 140 Ki Islands, Station 192. 500 Pacific, near the Meangis Islands, Station 214. 500-630 | Pacific—near the Kermadees, Station 170; near the Meangis Islands, Station 214. 65 Japan. | 388 THE VOYAGE OF H.M.S. CHALLENGER. Analysis of the above List. “ Poreupine.” Challenger. “ Blake.” Number of Gene ae Now Species Nine Species Nee Species Species. | PEVOUSY | Species, | PVIOUSY | Species. | Previously Holopus, : : 1 tye ae ie a ete 1 Hyocrinus, . ; 1 Yes Br 1 | Bathycrinus, . : 4 1 2 Rhizocrinus, . 2 1 11 2 2 | Pentacrinus, . : 9 | 1 ie 4 208 1 3 Metacrinus, . : 15 s a 11 a zs wee | Total known species, 32 3 1 18 2 1 6 It thus appears that (1) the cruises of the “ Porcupine” in 1869-70 added one genus and three species to the three genera and five species previously known. (2) More than half of the number (thirty-two) of known species, including two new genera, were discovered by the Challenger. (3) More than 65 per cent. of the known species have been dis- covered by H.M.SS. “ Porcupine” and Challenger; while the small number of genera known before 1869 has been doubled by the explorations of these two ships. BATHYMETRICAL TABLES. A Roman numeral opposite the name of a species shows that it also occurs in one of the other Tables. TasLE I.—Species found at depths down to 100 fathoms. Holopus rangi, I. | Pentacrinus miilleri, I1., I1I., TV. Rhizocrinus lofotensis, IT., I11., IV. V., VI.(?) | Metacrinus interruptus. rawsoni, IL, IIL., V., VI rotundus. Pentacrinus asterius,” 11., 111. Metacrinus sp. (Vega). decorus, II., III, IV. : 1 Dredged by the “Lightning” in 1868, if not by the “Porcupine” in 1869. See Proc. Roy. Soc. Edin., vol. xii. p. 356, 1884. 2 Two specimens in the Bristol Museum are believed to have been taken at a depth of 50 to 80 fathoms (Austin); and the earliest known examples must certainly have been obtained at depths above 100 fathoms. REPORT ON THE CRINOIDEA. TaBLeE I].—Species found at depths between 100 and 250 fathoms. Holopus rangi, 1. Pentacrinus miilleri, 1., I1., TV. Rhizocrinus lofotensis, 1., I11., 1V., V., VI. (2) | Metacrinus angulatus. rawsont, I., III., V., VI. cingulatus. Pentacrinus asterius, I., IIL. murray (2)." blake. nobilis. decorus, I., III., IV. tuberosus. TaBLeE II].—Species found at depths between 250 and 500 fathoms. Rhizocrinus lofotensis, 1., I, 1V., V., VI. (2) | Pentacrinus naresianus, V1. rawsoni, I., I., V., VI. Metacrinus costatus. Pentacrinus alternicirrus, TV. moseleyt. asterius, I., II. murrayt (2)? decorus, I., II., IV. Varians. maclearanus. wyvillir, IV. miilleri, I., I1., IV. Tas_e 1V.—Species found at depths between 500 and 700 fathoms. Rhizocrinus lofotensis, 1., I1., I1., V., V1. (2) | Pentacrinus miilleri, 1., U., TI. Pentacrinus alternicirrus, U1. Metacrinus nodosus. decorus, I., II., II. wyvillid, IIL. mollis. TABLE V.—Species found at depths between 700 and 1200 fathoms. Rhizocrinus lofotensis, L., 11., H11., 1V., VI. (2) | Bathycrinus carpenteri, VI. rawsont, I., I., IIL. Pentacrinus wyville-thomsoni. TaBLeE VI.—Species found at depths between 1200 and 2000 fathoms. Rhizocrinus lofotensis (?),’ L., IL, T1., 1V., V. | Bathycrinus carpenteri, V. rawsont, I., II., III., V. gracilis, VII. Bathycrinus aldrichianus. Hyocrinus bethellianus, VII. campbellianus. Pentacrinus naresianus, U1. Tasie VII.—Species found at depths between 2000 and 2500 fathoms. Bathycrinus gracilis, V1. | Hyocrinus bethellianus (?),* VI. 1 Tf at Station 192 ; 140 fathoms. 2 Tf at Stations 210 or 214 ; 375 and 500 fathoms. 3 Tf at Station 323 ; 1900 fathoms. 4 Tf at Station 223; 2325 fathoms. 389 390 THE VOYAGE OF H.M.S. CHALLENGER. Summary. A. I. 9 species found at depths down to 100 fathoms. I. 11 (or 12) species found between 100 and 250 fathoms. III. 13 (or 12) species found between 250 and 500 fathoms. IV. 7 species found between 500 and 700 fathoms. V. 4 species found between 700 and 1200 fathoms. VI. 8 species found between 1200 and 2000 fathoms. VII. 2 species found between 2000 and 2500 fathoms. B: 1 species descending from Table I. to IL. l 5 , I. to III. 2 ms fs I. to AEV. D e w Le towe vel 2 ‘5 - IH. to IV. 1 iS ia Ito “Ve 1 2 ie V, to VR 1 rr ” Vi. to. VIE C. 9 species found at depths down to 100 fathoms. 14 for 15) 4; a 250 - 29 ‘ 500, To these we may fairly add the two species of Metacrinus found near Singapore by one of the ships of the Eastern Telegraph Company, as it is improbable that they were living at a greater depth than 500 fathoms. It has been the custom of late years, more especially since the discovery of Penta- erinus wyville-thomsoni and Bathycrinus gracilis by the “ Porcupine,” at 1095 and 2435 fathoms respectively, to regard the Stalked Crinoids as pre-eminently abyssal types, and as probably forming “rather an important element in the abyssal fauna.”? It will be apparent, however, from the statistics given above, that subsequent researches have not altogether confirmed these views. If, as Mr. Agassiz has done in his Report on the Echinoidea,’ we take the limit of the continental line at 500 fathoms, it appears from Summary OC, that twenty-four of the thirty-two recent species of Stalked Crinoids, or 75 per cent., occur within this limit; while nine of these, living at depths less than 100 fathoms, may be called littoral. Although numerous and extensive dredgings have been carried on in the abyssal zone (.c., at depths below 500 fathoms) during the last fifteen years, Stalked Crinoids have 1 The Depths of the Sea, p. 455. 2 Zool. Chall. Exp., part ix. p. 222. REPORT ON THE CRINOIDEA. 391 only been found at thirty-four Stations. These have yielded thirteen species, representing five different genera, as shown in the following lists. Table showing the Number of Times that Stalked Crinoids have been Dredged in the Abyssal Zone. PRhizocrinus alone, . . ee ee Pentacrinus alone, 8 | Bathycrinus alone, 6 | Hyocrinus alone, : ery! Bathycrinus and Hyocrinus, 2 | Pentacrinus and Metacrinus, a | Rhizocrinus and Bathycrinus, 1 j N.B.—All the doubtful cases are included in this list. Table showing the Species of Stalked Crinoids which occur in the Abyssal Zone. . Continental Species Littoral Species G Species confined to the seas ier xenus. APcecal. Zone occurring in the occurring in the J : Abyssal Zone. Abyssal Zone. ( aldrichianus. campbellianus. Bathyerinus, . carpentert. | gracilis. Hyocrinus, . : : bethellianus. f mollis. { alternicirrus. Pentacrinus, - { wyville-thomsoni. { naresianus Metacrinus, . : : nodosus. woyvillii. ( lofotensis. | Rhizocrinus, . : | rawsoni. 8 3 2 392 THE VOYAGE OF H.M.S. CHALLENGER. Thus, then, thirteen species have been found in the abyssal zone, two of which are also littoral, while three are continental. The two former both belong to the genus Rhizocrinus, of which no exclusively abyssal species are known; though it has been met with at sixteen out of the thirty-four Stations in the abyssal zone. It is well represented in the Lower Tertiaries, and perhaps ranges back to the Cretaceous period, when its larger ally Bourgueticrinus was so abundant. : Pentacrinus has been found at nine Stations where the depth exceeded 500 fathoms ; and two of its four abyssal species are also continental. But on the other hand, Bathycrinus, which oceurs in the Atlantic at nine abyssal Stations between lat. 65° N. and 46° §., has never been found at a less depth than 1050 fathoms; while it embraces four out of the eight species which are peculiar to the abyssal zone. No fossil Bathycrinus is known, however, and the genus has no special affinities except with Ahizocrinus, of which it may almost be said to be the “‘benthal” ' representative. Of the four remaining abyssal species, one is the sole representative of the remarkable genus Hyocrinus, and has only been met with at 1600 fathoms and still greater depths. Like the Comatulid genus Thawmatocrinus, which occurs at 1800 fathoms in the Southern Ocean, it has certain strong points of resemblance to the Palzeocrinoids. Pentacrinus ranges back to the Trias and Rhizocrinus to the Eocene or Upper Cretaceous. But they are both abundant at depths of less than 100 fathoms, Pentacrinus occurring in the Pacific and in the East Indian Archipelago, as well as in the Atlantic and among the Caribbean Islands; while Rhizocrinus, though limited to the eastern hemisphere, ranges through over 100° of latitude. In spite, therefore, of the existence of a few characteristic abyssal types, it is some- what of an exaggeration to speak of the Stalked Crinoids as a group “on the verge of extinction,” of which a few survivors may occasionally be discovered in the deeper parts of the great ocean basins. 1 Dr. Gwyn Jeffreys has suggested that this word be employed to denote depths exceeding 1000 fathoms. See his address to the Biological Section at the Plymouth Meeting of the British Association, 1877, p. 79. APPENDIX. NOTE A. (Pages 2, 157, and 168.) On THE HoMoLoGIEs OF THE CRINOIDAL CALYX IN THE OTHER ECHINODERMS. Tue relations of the plates which enter into the composition of the calyx of a Crmoid to those constituting the apical system of an Urchin or a Starfish are still the subject of much discussion. The apical system of an Urchin, as described by Lovén,* consists typically of a dorso- central plate enclosed within two rings of five plates each. The plates of the proximal ring (genitals, Auct.) are interradial in position, while those of the outer ring (oculars) are radially situated. Believing that the dorsocentral is represented in the Pentacrinoid larva of a Comatula by the terminal plate at the base of the stem,” I have suggested that the basals of the Pentacrinoid are homologous with the so called genitals of an Urchin ; while the ocular plates of the latter correspond to the radials of the Crinoid. So far as the basals and radials are concerned this view is fundamentally the same as that previously expressed by Lovén and Agassiz, allowance being made for the difference between their terminology and that employed by myself; so that the homology between the basals and radials of a Crinoid and the two rows of plates surrounding the dorsocentral of an Urchin has been pretty generally accepted. Dr. R. Hoernes,? however, objects to this homology (which he associates with my name) on the ground that the resemblance should be most marked in the geologically oldest types, “ was keineswegs der Fall ist, da gerade der Scheitelapparat der Palaechinoiden durchaus nicht an die Basis-Entwickelung der Crinoiden-Kelches sich anschliesst.” This objection may be answered in two ways. 1. Lovén* says that the general formula of the apical system of Echinoidea “ has remained, more or less altered, but always recognis- able, from Palaeozoic to recent time.” 2. The positive fact that the basals and radials of 1 Etudes sur les Echinoidées, K. Svensk. Vetensk. Akad. Handl., Bd. xi., 1874, No. 7, p. 65. 2 Quart. Journ. Mier. Sci., 1878, vol. xviii., N. 8., p. 3874. 3 Blemente der Palzontologie (Palwozoologie), Leipzig, 1884, p. 130. 4 On Pourtalesia, a genus of Echinoidea, K. Svensk. Vetensk. Akad. Handl., Bd. xix., 1883, No. 7, p. 62. (zooL. CHALL. EXP,—PART xxxu,—1884.) ii 50 394 THE VOYAGE OF H.M.S. CHALLENGER. the Crinoid larva have precisely the same relation to the vaso-peritoneal system as the corresponding plates (genitals and oculars) of an Urchin is a strong reason for not laying too much stress upon the negative evidence of a confessedly imperfect paleontological record.* In one respect it is somewhat unfortunate that the Urchins should have been selected as affording the typical apical system of the Echinozoa, with which that of a Crinoid could be compared. For their apical system is primitively a comparatively simple one ; whereas many Crinoids have a ring of plates immediately beneath the basals which are unrepresented in the Urchins, though present in many Ophiurids and Asterids. In his endeavour to find an early Crinoidal form with a calyx of the same simple description as the apical system of an Urchin, Professor Lovén’ was led to select the genus Cyathocrinus (Poteriocrinus) ; and he proposed the following homologies between the two types :— 1. Dorsocentral of Urchin =the five under-basals of Cyathovrinus (the basals of J. Miiller). 2. Genitals of Urchin =the five basals of Cyathocrinus (the parabasals of J. Miiller). 3. Ocular plates of Urchin = radials of Cyathocrinus. The two last of these propositions have been generally, but not universally, accepted. As regards the first, however, I am sorry to say that I have found myself unable to agree with Professor Lovén. I pointed out six years ago® that the under-basals of Cyathocrinus constitute an element in the calyx which is by no means so constant in its occurrence as it should be, were it a fundamental part of the apical system and homologous with the dorsocentral of an Urchin or Starfish. Under-basals are present in Hncrinus, Extracrinus, and Marsu- pites among the Neocrinoids, and in Cyathocrinus, Poteriocrinus, Rhodocrinus, and a large number of allied genera among the Palocrinoids ; while they are absent in Apio- crinus, Pentacrinus, Actinocrinus, Platycrinus, and in many other less known genera. When present, there are generally five distinct plates, resting on the upper stem-joint ; and this fact, together with the want of constancy in their occurrence, caused me to suspect that they could not be collectively homologous to the primitively single dorso- central plate of an Urchin or Starfish, as supposed by Lovén. -I was therefore led to seek for the homologue of this last in the terminal plate at the end of the stem of the Pentacrinoid larva, which occupies the same position with regard to the right peritoneal tube as the dorsocentral of a larval Urchin or Starfish. This suggestion has been accepted by Liitken and by Sladen, as I have pointed out above (p. 168), though it is altogether ignored by Lovén. But no serious arguments have been yet brought forward against it by other authors who have discussed the question ; while, on the other hand, 1 Dr. Hoernes does not appear to have gone into the subject very deeply. I have nowhere suggested that the radials of an Urehin are homologous with the basals of a Crinoid; nor that the madreporite of Clypeaster is compar- able to the centro-dorsal of Comatula and to the central plate in the calyx of Marsupites. Nevertheless Hoernes thinks fit to express his dissent from these views, which have originated with no one but himself, and he entirely misses the real point at issue. : 2 Etudes, loc. cit., p. 80. 3 Quart. Journ. Micr. Sci., 1878, vol. xviii., N. S., pp. 358-361. REPORT ON THE CRINOIDEA. 395 several recent researches have supplied further cogent reasons for rejecting the homologies which Loyvén seeks to establish between the dorsocentral of an Urchin or Starfish and the under-basals of a dicyclic Crinoid. Six years ago the numerous modifications of the apical system which are presented by Asterids and Ophiurids had received comparatively little attention; and I was therefore led to regard the under-basals of Encrinus, Extracrinus, and of the Paleozoic Crinoids as “additional elements which occur in the apical system of some Crinoids, while they are unrepresented in other members of the order and in the other Echino- derms.”’ Four years later, however,’ I was able to show that the apical system of the young Amphiura squamata, which had been recently described by Ludwig,’ corresponded precisely. with that of Marsupites, the type which was first selected by Lovén for comparison with Salenia. Both in Amphiura and in Marsupites there is a central abactinal plate representing the dorsocentral of an Urchin. Next to this come, not the interradial plates corresponding to the genitals of an Urchin and the basals of Cyathocrinus, as Lovén formerly supposed,* but a ring of radially situated plates which correspond to the under-basals of Cyathocrinus, but are not represented at all in the apical system of an Urchin, as at present known. Outside these come the interradial basals (genitals) and then the radials (oculars). Ludwig discovered that the latter remain on the disk of Amphiura, and are not carried away from it by the growing arms as had been generally supposed. Having discovered, as I believed, the homologues of the under-basals of a Crinoid in a larval Ophiurid, I naturally began to seek for them in the adult members of the class; and it soon appeared that they were represented in the rosette of primary plates which occupies the centre of the disk in certain species of Ophioglypha, Ophioceramis, Ophiomusium, and Ophiozona.’ At the same time two important discoveries bearing on this question were made by Sladen.° (1) The radial plates of the larval Asterid remain on the disk, like those of the Ophiurid, and are not carried outwards by the growing arms, as was formerly supposed. (2) In the late larvee of Zoroaster fulgens, Asterina gibbosa, Asterias rubens, Asterias glacialis, and other species, the so called genital plates (=basals of a Crinoid) are separated from the dorsocentral by a ring of radial plates which occupy exactly the same position as the under-basals of Marswpites, and the corresponding plates in the Ophiurids mentioned 1 Quart. Journ. Micr. Sci., 1878, vol. xviil., N. S., p. 374. 2 Tbid., 1882, vol. xxii. p. 380. 3 Zur Entwicklungsgeschichte des Ophiurenskelettes, Zeitsclr. f. wiss. Zool.; Bd. xxxvi. 1882, pp. 181-200, Tafn. x., xi. * Lovén appears to have been so far influenced by my criticisms on his comparison of the radially placed under-basals of Mursupites with the interradial genitals of Salenia that he makes no further reference to the former type, although in his earlier “ Btudes” he laid great stress upon its resemblance to Salenia. This is unfortunate, because the presence of a dorsocentral in Marsupites, as well as of under-basals homologous with those of Cyathocrinus, proves conclusively that the latter cannot represent the dorsocentral of Marsupites, and therefore of Salenia, as Lovén formerly supposed. 5 Quart. Journ. Micr. Sci., 1884, vol. xxiv., N. 8., p. 11. 6 Ibid., pp. 29-34. 396 THE VOYAGE OF H.M.S. CHALLENGER. above. Further, these plates “are large and well-developed in the adult forms in Pentagonaster semilunatus, Gymnasteria carinifera, in various species of Pentaceros, and a large number of the Goniasteride.” It thus appears that a small number of Ophiurids and a larger number of Starfishes have two rings of plates between the radials and the dorsocentral, Just as is the case in Marsupites; though in the majority of the members of both groups there is only one ring, the elements of which are interradial, as is the case in all the Urchins, so far as is yet known. The homology of these interradial plates with the basals of the Penta- crinoid larva and of Marsupites is a part of Lovén’s theory; while he long ago pointed out the homology between the central abactinal plate of the Starfish larva and the dorso- central of Marsupites.' I do not see therefore, how he can do. otherwise than accept the views of Sladen and myself respecting the homology of the radial plates immediately surrounding the dorsocentral of Ophiomusium, Amphiura, Asterias, and Zoroaster with the under-basals of Marsupites. In both cases these radial plates separate the dorso- central from an interradial series which are called basals in a Crinoid and genitals in an Urchin or Starfish, z.e., the plates for which Lovén proposes the general name of “costals.” Ido not imagine that he will deny (1) that the radial plates between the costals and dorsocentral of Marsupites are homologous with the radial plates between the costals and dorsocentral of the young Asterias; nor (2) that these radial plates are homologous with the under-basals of Cyathocrinus, which are immediately within the basals, or as he prefers to call them, costals. But, according to his present view, these under-basals of Cyathocrinus represent the dorsocentral of the young Asterias. There is, however, no reason to seek for the homologue of the five under-basals of a dicyclic Crinoid in the single dorsocentral of a larval Starfish; for this dorsocentral is surrounded by five plates which correspond exactly in their relative positions with the under-basals of Marsupites, and therefore of other dicyclic Crinoids, including Cyathocrinus. If I may be permitted to use here an expression employed by Prof. Lovén with respect to another homology which he establishes, I would say that ‘‘ to anyone believing in the consistency of Nature’s ways, there is no reason whatever for doubting” that the apical systems of some Asterids and Ophiurids contain plates which are truly homologous with the under-basals of a Crinoid. It is unfortunate that their presence was not discovered in time to be noticed by Prof. Lovén in his recent discussion of the question; for I am sanguine enough to believe that it would have led him to reconsider his views respecting the homology of the five under-basals of a Crinoid with the primitively single dorso- central of a Starfish. The interradial plates in the apical system of a Starfish or Urchin are usually known as the genitals; but this term, ‘‘ besides being expressive of incidental relations peculiar 1 Etudes, loc. cit., pp. 72, 86. REPORT ON THE CRINOIDEA. 397 to the Echinoidea and partly to the Asteriadea, cannot by any means be applied to the homologous parts in the Crinoid,” 7.e., to the basal plates. Lovén,’ however, objects to the extension of the latter name to the so called genitals of Urchins and Starfishes, because the position of their apical plates, “while basal in the Crinoidea, is culminating in the Echinoidea and the Asteriadea, and consequently any appellation involving the notion of ~ a basal position must be avoided.” There is undoubtedly some force in this objection ; and I have long been endeavouring to find some general expression that would conveniently describe the interradial plates in the apical system of all Echinoderms. Not having succeeded in this quest, I have been obliged to fall back upon the word “ basals.” The interradial position of these plates in the calyx of a Crinoid, as defined by Miiller,’ is now universally recognised, and the use of the word is not likely therefore to lead to any confusion respecting the position of the plates with regard to the general symmetry of the Echinoderm type; while it has the further advantage of avoiding the multiplication of “terms already too numerous.” As Lovén objects to the use of “basals” for the reasons given above, he seeks to avoid the introduction of new names by reviving the old term “costals” of Miller. To this there could be no possible objection were it only employed in the sense in which it was generally used by Miller, but this is unfortunately not the case. In seven out of the nine genera which were described by Miller as having costal plates, this term was used for the radial plates of the calyx ; while it was only in describing some species (not all) of Cyathocrinus that he employed the term costals, for the interradial plates of the calyx or basals, and in the case of Marsupites he gave this it has always been considered allowable to suggest the use in a strict sense of a term elsewhere vaguely applied.” This is of course quite true, but the term should surely be limited to that sense in which it was most generally used by its author. This is not the case, ce name to the under-basals. Lovén admits this inconsistency,* but adds that however, with Lovén’s revival of the term “ costals,” for he employs it to designate the basal plates which were only called costals by Miller in four out of the many species described by him; while he applied this name to the radials in all the other cases in which he used it at all, except in that of Marsupites. I cannot help feeling, therefore, that this revival of a name which has been disused for half a century is somewhat inexpedient, and is likely to lead to a confusion between the radial and interradial plates of the apical system which it is very desirable to avoid. Every one knows that the interradial abactinal plates of an Urchin or Starfish are not situated at the base of its body as they are in a Crinoid ; and this reservation being made I do not see that there can be any objection to calling them basal plates. This would avoid all possibility of any confusion with respect to their position as regards the general symmetry of the 1 On Pourtalesia, loc. cit., p. 63. 2 Itmay be noted with respect to this point that when Lovén inverts an Urchin for a better comparison of its calyx with that of a Crinoid, his “ costal” plates (the genitals) really do become “ basal” in position (see p. 414). 3 Bau des Pentacrinus, loc. cit., p. 25. 4 On Pourtalesia, loc. cit., pp. 63, 64. 398 * THE VOYAGE OF H.M.S. CHALLENGER. Echinoderm, which seems to be inseparable from Lovén’s use of the term. Should Prof. Lovén ever write anything more upon the apical system of Echinoderms, he cannot avoid referring to the radial plates between the dorsocentral and the so called genitals (costals or basals) of an Asterid. He cannot speak of them by the name which was given them by Sladen who discovered them, viz., ‘ under-basals,” for this term would be meaning- less and confusing unless the plates outside them (the costals of Lovén) were also called - basals ; and he would therefore have to invent a new name for them, a proceeding to which he objects, or else adopt the terminology of Sladen and myself. I am sanguine enough to hope, not only that this will be the case, but also that the presence in Asterids and Ophiurids of plates homologous with the under-basals of Crinoids will lead him to abandon his theory of the homology of these under-basals with the dorsocentral of an Urchin or Starfish. I little expected six years ago to get so complete a confirmation of the views I then expressed as the presence of a “ dicyclic base” in several Asterids and Ophiurids as well as in Cyathocrinus and Marsupites. The similarity “in structure of the apical system in all the groups of brachiate Echinoderms thus becomes exceedingly striking; and it affords a further proof (if such were needed) of the homology between the apical systems of the Echinozoa and the Pelmatozoa respectively. Two authors, however, have been led to an entirely different conclusion respecting the interradial abactinal plates of the Starfish larva from that of Lovén, Agassiz, Sladen, and myself. Ludwig regards them as homologous with the orals of a Crinoid, because one of the latter is pierced by the primitive water-tube;* while the madreporite of an adult Starfish is in relation with one of the so called genital plates (costals or basals). The morphological difficulties inseparable from this inversion of the relations between a Starfish and a Crinoid, as ordinarily conceived, have been discussed by Sladen? and myself.* With the exception of Studer,‘ whose errors have been discussed elsewhere,* no other writer has alluded to the subject; though it has recently made its appearanee in a somewhat modified form. Perrier stated two years ago ° that the primary interradial plates around the dorsocentral of the young Brisinga develop into the so called odontophores of the adult. The former are the plates which are usually known as the genitals (costals of Lovén; basals of Sladen and myself); and if Perrier’s statement be correct, the views of Lovén, Agassiz, Sladen, and myself respecting the homology of the apical plates through the whole group of Echinoderms are no longer tenable. No proofs of it have yet been offered, however, though in a later note by Perrier’ the following passage appears, “Les jeunes Astéries, les jeunes Brisinga présentent aussi, comme Lovén et nous-méme 1 Zeitschr. f. wiss. Zool. Bd. xxxiv. p. 318, 1880. 2 Quart. Journ. Micr, Sci., 1884, vol. xxiv., N. S., pp. 35-40. 3 Ibid., 1880, vol. xx., N. S., pp. 322-329. * Uebersicht tber die Ophiuriden welche wihrend der Reise S.M.S. “Gazelle” um die Erde, 1874-76, gesammelt wurden, Abhandl. d. k. Akad. d. Wiss. Berlin, aus dem Jahre 1882, Phys. Kl. Abh., i. p. 10. 5 Quart. Journ. Mier. Sci., 1884, vol. xxiv., N. S., pp. 15-18. ® Note sur les Brisinga, Comptes rendus, t. xev., 1882, p. 63. 7 Ibid., p. 1381. i. ah REPORT ON THE CRINOIDEA. . 399 V'avons etabli, des plaques dorsales disposées au début, comme celles du calice des Crinoides ; nous avons démontré que, chez les Brisinga, les plaques de la premiere rangée deviennent les odontophores.” Even yet, however, no figures of the various develop- mental stages of Brisinga have been published in “ demonstration” of Perrier’s statements, which were summarised as follows, “ Aisi les odontophores sont les restes des pitces du premier rang du disque primitif de la Brisinga. Lidentité évidente du plan dorganisation des Brisinga et des Astéries proprement dites rend la méme conclu- sion probable pour les autres Etoiles de mer.” It is undoubtedly probable that what is true of Brisinga also applies to all the other Asterids ; and it is therefore the more desirable that some proof should be offered of the very definite statements made by Perrier. They have recently been disputed by Sladen! on the ground that in all the Starfishes of which the embryonic stages are sufliciently known, the basals and odonto- phores are “ separate and distinct, and co-exist independently from their first formation ;” while he further expresses his belief, based on sound morphological argumeuts, that the origin assigned by Perrier to the odontophores of an Asterid is theoretically impossible. Perrier has recently repeated his statements in somewhat greater detail,’ and having compared Lovén’s figures of the young Asterias glacialis with his young specimens of Brisinga, he says that he has no doubt whatever, “que les choses se passent de la méme facon dans les deux genres, et nous pouvons, dés lors, affirmer que les piéces radiales (sic) des tres jeunes Asteriadze deviennent dans cette ordre de Stellérides les odontophores.” Unfortunately for his theory, however, these interradial abactinal plates of the young Asterias develop in other Starfishes into relatively large plates which remain in more or less close relation with the dorsocentral, and are the very plates described as basals by Sladen not only in the larval Asterias, but also in the following genera Zorouster,? Pentagonaster, Tosia, Astrogonium, Stellaster, Nectria, Ferdina, Pentaceros, Gymnasteria, and others. As there is an odontophore on the ventral side in each of these types, it is perfectly 1 Quart. Journ. Mier. Sci., 1884, vol. xxiv., N. S., p. 39. 2 Mémoire sur les Etoiles de Mer recueillies dans la mer des Antilles et le Golfe du Mexique durant les expéditions de dragage faites sous la direction de M. Alexandre Agassiz, Nouv. Archiv. du Mus. @ Hist: Nat., 2™° sér., 1884, t. vi. p. 159. 3 Several months before the appearance of Perrier’s Report upon the West Indian Starfishes, Sladen figured the apical system of Zoroaster fulgens, and described it in the following terms: “Surrounding a dorsocentral and five small radially placed plates are five large plates interradial in position ; and outside and alternating with these are five similar but rather smaller radially placed plates. . . . It will be noted that these plates represent in a remarkable manner the dorsocentral, the under-basals, the basals, and the radials respectively of the Crinoid calyx” (Asteroidea dredged in the Farée Channel during the cruise of H.M.S. “Triton” in August 1882, Trans. Roy. Soc. Edin., vol. Xxxii. p. 160, figs. 9,11). Precisely the same arrangement appears in the apical system of Zoroaster ackleyi, so far as one can judge from Perrier’s figure of an entire specimen (Nouv. Archiv. du Mus. @ Hist. Nat., 2™° sér., 1884, t. vi. pl. iti. fig. 1)5 but he makes no mention of Zoroaster fulgens. Even if he had not seen Sladen’s reference to it, one would have thought that he would have been struck by the Crinoidal aspect of Zoroaster ackley?, though he does not refer to it at all, and he gives no detailed description of the plates. It would be interesting to know his reasons for believing that the large interradial plates in the immediate neighbourhood of the dorsocentral are not the “plaques de la premitre rangée” of the larva, which occupy exactly the same position with reference to the dorsocentral, and are believed by Perrier to become the odontophores in all Starfishes except Caulaster. 400 THE VOYAGE OF H.M.S. CHALLENGER. clear that this structure cannot have been developed from the primary interradial plates in the abactinal system of the larva; for these last remain in the apical system, just as they do in the Urchins. Sladen’s observations, to say nothing of those of Lovén, render Perrier’s views respecting the development of the odontophores of an Asterias from the primary interradial plates round the dorsocentral of the larva, absolutely untenable, and one is therefore the less disposed to accept his statements concerning Brisinga, of which no proof has yet been offered to his fellow-workers. In connection with this subject he has recently advanced some theories respecting the mutual relations of a Crinoid and an Urchin which are altogether at variance with those of most other naturalists, except perhaps Ludwig. He thinks that in comparing the apical system of an Urchin with the calyx of a Crinoid, Lovén “a attribué & l’Oursin une position exactement inverse de sa position normale.”’ He regards an Urchin as a Crinoid with a large visceral mass to which the arms are fixed, as for example in Eucalyptocrinus ;” while “la bouche serait située au point d'insertion du disque sur la tige.” Under these circumstances the nervous system and ambulacral canals of an ce Urchin would have “exactement les mémes rapports que ceux qui nous sont offerts par la Comatule. 11 est & remarquer que précisément, en ce point, le calice de nombreux Crinoides pédonculés s’invagine, et présente des plaques qui ne sont pas sans analogie avee celles qui constituent la Janterne d’Aristote des Oursins et plus particulitrement des Clypéastres.” This idea has since been further developed.? The arms of a Crinoid grow at their free end, while the new ambulacral plates of an Urchin are formed round the periproct. The base of the ambulacra is thus in the peristome. ‘Mais alors les pieces homologues des plaques calicinales des Crinoides sont non pas les dix plaques du périprocte, mais bien les pieces constitutives de la lanterne d’Aristote. Quelque hardie que paraisse cette interprétation . .... . nous sommes persuadé que tout esprit non prévenu sera frappé de I’étroite ressemblance d'un Oursin régulier avec des Crinoides tels que le Calherinus et surtout les Eucalyptocrinus.” I fear that in this matter I cannot be said to have an “esprit non prévenu”; but it certainly appears to me somewhat rash to attempt to overthrow the generally accepted ideas respecting the mutual relations of an Urchin and a Crinoid by reference to such very highly specialised types as Hucalyptocrinus and Callicrinus. Both in this respect and in the comparison of the Crinoidal calyx to the lantern of Aristotle, I cannot help feeling that Prof. Perrier has altogether lost sight of the embryological arguments by which questions of homology are generally decided. The calyx of a Crinoid and the apical system of an Urchin or Starfish have precisely the same relations to the vaso- peritoneal apparatus of the larval Echinoderm; and until some better reason can be adduced for disregarding this relation than a more or less uncertain resemblance between Now. Archiv. du Mus. @ Hist. Nat., 2™° sér., 1884, t. vi. p. 161. 2 Comptes rendus, t. xcvill. p. 1450, Nouv. Archiv. du Mus, d’ Hist. Nat., 2m sér., 1884, t. vi. p. 161. 1 3 REPORT ON THE CRINOIDEA. 401 a stemless Urchin and a highly specialised Paleeocrinoid, I think that most naturalists will be inclined to regard the mouth of an Urchin as representing that of a Crinoid, and not the point of attachment between the stem and the body. If this last view be correct, it follows, as Perrier points out, that ‘le dos des Astéries correspondrait & la region buccale des Oursins et non leur region anale,” which not even Ludwig would assert. Two years ago Perrier described a small Starfish which had been dredged by the “ Travailleur,” and was distinguished by the possession of a small dorsal appendage comparable to the stem of a Crinoid.'| He stated that “quelques caractéres des Astéries dont nous avons & parler ici paraissent indiquer que Tappendice dorsal dont elles sont munies est bien réellement homologue du pédoncule des Crinoides.” He named the type Caulaster, and added that it is allied to Ctenodiscus. “Tl existe chez ces derniers un léger tubercule qui nous parait homologue de Yappendice dorsal des Caulaster, et peut-étre en pourrait-on rapprocher un bouton saillant qui, chez les Astropecten, occupe la place ot se trouve anus chez les autres Etoiles de mer.” Sladen subsequently pointed out that a central epiproctal prominence of this kind is very general in the family Astropectinide.’ It is “frequently developed into an elongate tubular prolongation” in the subfamily Porcellanasteride. He doubted the affinity of Caulaster with Ctenodiscus, and was inclined to regard it as a young Porcellanaster. More recently Danielssen and Koren? have described a new genus Tlyaster, in which a disk of 30 mm, diameter bears an epiproctal process 8 mm. long and covered with paxille, as in the Astropectinidee described by Sladen. They agree with Perrier in regarding it as homologous with the stem of a Crinoid; and it would appear that Agassiz is of the same opinion.* It may be that this view of the case is the ‘right one; but it could only be satisfactorily proved to be so by the demonstration that the cavity of the epiproctal prolongation is derived from the right vaso-peritoneal tube. For it is a diverticulum of this division of the primitive body-cavity of Comatula which extends backwards and has the joints of the larval stem developed in its walls. Future observations upon the early larval stages of the Astropectinides would throw much hight upon this question. Perrier’s Caulaster appears to be the youngest known form pos- sessing this curious appendage, and some of the plates of the primitive calycular system are still visible. “A la base de Yappendice dorsal, se trouvent en effet quatre grandes plaques calcaires, disposées en croix et portant chacune un petit piquant; ces plaques sont X peu pres orientées dans la direction des bras; wne cinquitme plaque, alterne avec deux d’entre elles et opposée & la plaque madréporique, fait évidemment partie du méme cycle; cing autres plaques plus petites viennent se placer dans les angles laissés libres par les cing plaques de la premiere rangée. On ne peut manquer Vétre frappé 1 Comptes rendus, t. xev. p. 1379. 2 Journ. Linn. Soc. Lond. (Zool.), vol. xvii. p. 214. 3 Den Norske Nordhays-Expedition, xi.; Zoologie. Asteroidea, p. 101, pl. vil. fig. 16, 1884. 4 Reports on the Results of Dredging by the U.S. Coast Survey steamer “Blake” ; Report on the Echini, Mem. Mus. Comp. Zodl., vol. x., 1883, No. 7, p. 17. (zoOL. CHALL. EXP,—PART XxxiI.—1884,) hi dl 402 THE VOYAGE OF H.M.S. CHALLENGER. de la ressemblance absolue de ces dix plaques alternes avec celles qui forment le périprocte des Oursins et que Lovén a rapprochées, & leur tour, de celles qui constituent le calice des Crinoides, opinion que nous aurons prochainement occasion de discuter. L/identité de dis- position des plaques dorsales des Caulaster avec celles du calice de Crinoides est évidente.” It would appear, however, from the foregoing description that Perrier’s comparison of the plates round the dorsal appendage of Caulaster with those forming the periproct of an Urchin cannot be followed out in detail. The first row of plates in Caulaster, if radially situated as Perrier states, cannot correspond to the first or inner row of the apical system of an Urchin; for these last are the genitals, and are situated interradially. Their homologues are the plates in the second row of Cauwlaster, which alternate with those of the first; while the second ring of plates in the Urchins, the oculars or true radials, appear not to be represented in Cawlaster. If Perrier’s description of the positions of the plates in this type be correct, its apical system consists, not of genitals and oculars (basals and radials) as in an Urchin, but of under-basals and basals ; and the true radials must be so small as to have escaped his notice. NOTE B. (Page 36.) On THE Basats oF Fossin CoMATULa. In certain fossil Comatule the ends of the basals are visible on the exterior of the calyx between the radials and the centro-dorsal. They are sometimes quite small, as in some forms of Pentacrinus decorus (Pl. XXXIV. fig. 1; Pl. XXXV. figs. 1, 2; Pl. XXXVI. fig. 3); while in other species, such as Solanocrinus scrobiculatus, Miinster, they may reach a considerable size. As long as basals were supposed to be absent in the calyx of the recent Comatule, their presence in fossil forms appeared to be a character of generic value. But after the discovery by Dr. Carpenter and Sir Wyville Thomson that the Pentacrinoid larva has true basal plates which eventually become metamorphosed into the concealed rosette, this distinction between the recent and fossil Comatulz no longer holds good. Schliiter* recognised this fact in 1878, and pointed out that Solanocrinus was merely a synonym of de Freminville’s name Antedon. He referred to this genus both Solanocrinus costatus, Goldfuss, and Solanocrinus scrobiculatus, Minster, together with two other fossil species, in both of which the basals appear on the exterior of the calyx. Zittel,” however, regarded Solanocrinus as a subgenus of Antedon, distinguished from it by the presence of external basals. In the following year® the examination of a considerable number of fossil Comatulee 1 Zeitschr. d. deutsch. geol. Gesellsch., Jahre. 1878, pp. 36, 40. 2 Palontologie, vol. i. p. 396. 3 On some undeseribed Comatule from the British Secondary Rocks, Quart. Journ. Geol. Soc., vol. xxxvi. pp. 36-46, 1880. REPORT ON THE CRINOIDEA. 403 led me to adopt Schliiter’s view, as de Loriol* had previously done. For I not unfre- quently met with calyces in which basals might appear externally at some of the angles, but not at others; while in other fossil types no basals were visible at all, In both cases, however, the basals were present as more or less prismatic rods extending outwards from the centre of the under surface of the radial pentagon somewhat as in the Pentacrinus decorus represented in Pl. XXXIV. fig. 8. But they were not always long enough to reach the edge of the radial pentagon and appear externally between it and the centro- dorsal; so that one side of a calyx would be that of an Antedon and the other that of a Solanocrinus. Under these circumstances it would seem that Schliiter was undoubtedly right in uniting Solanocrinus with Antedon. But in a Manual of Paleontology recently published by Hoernes,” Zittel’s classification is still adopted, and Solanoerinus is placed as a subgenus of Antedon, differing from it in the presence of basals on the exterior of the calyx; while it is also described as represented by a living species and not by fossil ones only. This apparently refers to the doubtful genus Comaster, Agassiz, which is only known from the description given of it by Goldfuss.* Whatever be the nature of Comaster, however, the supposed difference between Solanocrinus and Antedon cannot any longer be regarded as of generic value. NOTE C. (Page 68.) On THE Excentric Posrrion oF THE Mout IN Actinometra. The genus Actinometra comprises quite two-fifths, if not more, of all the species of living Crinoids. The character by which it is most readily distinguished at first sight is the excentric position of the mouth, as was pointed out in 18774 and again in 1879 ;° while its generic position is recognised by Claus in the last edition of his Grundziige der Zoologie with the character “Mund excentrisch” (PI. LV. figs. 1, 2; PEGA, fies? 778; Pl. LXI. fig. 2; see also fig. 3 on p. 92). In spite of these facts, however, Hoernes stated in his Paleontology (p. 131) that in recent Crinoids the mouth is always (stets) in the centre of the disk, which is very far from being the case, as explained above. This error was avoided by Zittel, whom Hoernes usually follows very closely ; though the generic position of Actinometra was not fully recognised by the former author, who placed it along with Solanoerinus and Promacho- crinus as a subgenus of Antedon. But all subsequent writers, Hoernes excepted, have recognised that Antedon and Actinometra are totally distinct generic types. 1 Swiss Crinoids, p. 254. 2 Elemente der Palwontologie, p. 149. 3 Petrefacta Germaniz, vol. i. p. 202 ; see also Journ. Linn. Soc. Lond. (Zool.), vol. xiii. p. 454, 1877. 4 Journ. Linn. Soc. Lond. (Zool.), vol. xiii, p. 441, 1877. 5 The Genus Actinometra, Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. ii. p. 18. 404 THE VOYAGE OF H.M.S. CHALLENGER. NOTE D. (Pages 100, 106.) ON THE SUPPOSED COMMUNICATION OF THE CHAMBERED ORGAN AND LapiaL PLexvus witH THE EXTERIOR. Perrier’s statements respecting the direct continuity of the water-tubes depending from the oral ring of the larva with the inner ends of the water-pores of the disk have recently been extended to the adult Antedon. He further asserts not only that some of the water-pores open into the more or less glandular tubules of the labial plexus, but also that the canals forming the inner ends of the water-pores on the lower part of the disk open into the cavities of the chambered organ.’ I will not go so far as to deny the truth of these statements; but can only say that the results which Prof. Perrier believes himself to have obtained by “1’étude minutieuse de plus de deux cents coupes” are far from being in accordance with those of Ludwig, Greeff, Teuscher, or myself. It seems to me unlikely that the complex relations of the canals forming the inner ends of the water-pores which Perrier describes should have entirely escaped the notice of all of us. I freely admit that I may have overlooked the connection of the water-pores with the water-tubes and with the labial plexus; for the state of preser- vation of my material has not been such as to yield sections of one-fortieth of a millimeter thick. But, on the other hand, I have carefully studied many more than two hundred sections, nearer two thousand in fact, of several different types; and I believe it to be impossible that I could have avoided seeing such a connection between the water-pores and the chambered organ as is described in the following sentence, “leur plexus se continue jusqu’& Vorgane cloisonné dans les chambres duquel s’ouvrent encore chez l'Antedon rosaceus les canaux issus des entonnoirs inférieurs du disque.” The chambered organ of a Comatula is lodged within the cavity of the centro-dorsal basin, covered up by the rosette, and surrounded by the ring of united first radials (PL LXI. fig. 2). It is therefore a perfect mystery to me how any of these canals which lead inwards from the ciliated water-pores and traverse the perisome of the disk can possibly open into its chambers. Perrier describes himself as having been the first since the time of Miiller to draw attention to these ciliated water-pores ;? and he gives the date of his having done so as 1872.3. In making this claim, however, he entirely ignores the fact that on the 21st of March 1871 Grimm had communicated a description of them with illustrative figures to the St. Petersburg Academy.‘ His description and figures were published in 1872, and 1 Anatomie des Echinodermes ; sur Vorganisation des Comatules adultes, Comptes rendus, t. xeviii., No. 23, 1884, p. 1449, 2 Comptes rendus, t. xcviii. p. 1449. * Recherches sur l’anatomie et la régénération des bras de la Comatula rosacea, Archives d. Zool. expér., vol. ii. p. 42. * Zum feineren Bau der Crinoiden, Bull. Acad. Sci. St. Petersb., t. xvii., 1872, col. 3-9, Mit einer Tafel. REPORT ON THE CRINOIDEA. 405 Perrier cannot well be unaware of the fact at the present time, as it is noticed in the text of Ludwig’s work on the Crinoids, and the paper is properly quoted in his bibliography. It is difficult, therefore, to see on what grounds Perrier bases his claim respecting the re- discovery of these ciliated funnels, ‘sur lesquels, depuis Johannes Miller, jai le premier attiré lattention (1872).” When he published the paper here referred to, he had only made a superficial examination of these openings, each of which he described as leading into a small cul-de-sac. It would seem indeed as if he were then unaware, not only of Grimm’s more correct observations of the previous year, which may be readily understood, but also of Miiller’s description of these pores published nearly thirty years before ;* for he never mentioned Miiller at all, and suggested that the pores might be special sense organs! Now, however, he tells us that they have a threefold connection—(1) with the water-vascular ring ; (2) with the plexus of glandular tubules round the gullet ; (3) with the cavities of the chambered organ. No other observers have noticed these points, and Prof. Perrier’s proofs of his statements will be awaited with much interest. NOTE E. (Page 102.) ON THE INTERVISCERAL BLooD-VESSELS. Perrier admits in his latest note* that diverticula of the cavity of the axial organ extend through the coelom, and that while some of them “apparaissent sur les coupes comme terminés en culs-de-sac, d’autres se plongent manifestement en canaux. Quelques- uns de ces canaux courent parmi les trabécules innombrables de la cavité générale ; il en est qui se rendent vers les bras.” Some of these canals, which are regarded by Ludwig and myself as the intervisceral blood-vessels, are represented in Pl. LVII. figs. 2-5 and Pl. LX. figs. 3, 5—ib. If they are merely parts of a “vaste systeme aquifére,” as Perrier believes, it is difficult to understand their existence; for the body-cavity through which they ramify already contains water which has entered it by the water-pores of the disk. What then is the object of a special set of aquiferous tubes distributed over the coils of the digestive canal and not communicating with the ambulacral system, but with the axial organ and the labial plexus ; and why is it that their lumen is so frequently filled up with coagulum ? NOTE F. (Page 106.) ON THE RELATION OF THE VASCULAR SysTEMS OF A CRINOID TO THOSE OF THE OTHER ECHINODERMS. ' Perrier’s latest views respecting the vascular system of a Crinoid are expressed in the 1 Durch diese capillaren Poren kann das Wasser bis in die Nihe des im Kelch liegenden Eingeweidesacks eindringen (Bau des Pentacrinus, loc. cit., p. 49; see also the Bau der Echinodermen, loc. cit., p. 63). 2 Comptes rendus, t. xevili. p. 1449. 406 THE VOYAGE OF H.M.S. CHALLENGER. following passage :'—“ Ainsi le plus grande nombre des entonnoirs ciliés, Vorgane spongieux, Porgane axial, les chambres de l’organe cloisonné, ne forment qu'un seul et méme systeme, d la fois ’analogue et ’homologue du systtme formé chez les Oursins, les Astéries et les Ophiures par la plaque madréporique, le canal hydrophore ou canal du sable et la glande ovoide qui lui est constamment annexée.” The above statement harmonises admirably with the theory which Perrier has so long been advocating respecting the fundamental unity of what are generally known as the water-vascular and the blood-vascular systems of Echinoderms. This theory is by no means new, and appeared to receive confirmation from the results of Perrier’s study of the circulatory apparatus of the Urchins.” But Koehler’s later observations on the same subject * have shown that several important points in the anatomy of the vascular system of an Urchin entirely escaped Perrier’s notice. Although he adopts Perrier’s views, his observations are capable of an altogether different interpretation, as I have shown elsewhere ;* while they afford a strong confirmation to Ludwig’s description of the vascular system of the Asterids.’ This was founded upon the most careful and elaborate observations which have yet been published; and although their correctness has been called in question by Messrs. Perrier and Poirier,® none of the French zoologists have published a single figure in proof of their assertion that what is generally called the blood- vascular system of a Starfish communicates with the exterior through the madreporite. As regards both Starfishes and Urchins therefore, the latest and most detailed observations do not tend to support the views of the French school. With respect to the Crinoids, however, the results which Perrier describes himself as having obtained, fall in with his theory in a manner which leaves nothing to be desired for completeness. In the case of the Urchins, according to Koehler, Perrier saw too little; while his two hundred Comatula-sections have revealed more to him than has resulted from all the observations of Ludwig, Teuscher, Greeff, and myself; and we, not Perrier, have ‘seen too little. His theory, however, breaks down completely unless he can prove to the satisfaction of his colleagues that the labial plexus and chambered organ of a Crinoid are in direct communication with the exterior through the water-pores of the disk. Unless these points can be properly demonstrated, the doctrine that the water- vessels and intervisceral blood-vessels of a Crinoid are only parts of a “vaste systéme aquifére ” will have to be abandoned ; while it does not harmonise at all with the present state of our knowledge of the morphology of the Echinozoa, except in so far as this is based upon the observations of the French Zoologists. Comptes rendus, t. xevili. p. 1449. Recherches sur l’Appareil circulatoire des Oursins, Archives d. Zool. expér.,vol.iv., 1875, pp. 605-643, pls. xxiii. xxiv. Recherches sur les Echinides des Cotes de Provence, loc. cit., pp. 58-79. Quart. Journ. Micr. Sci., 1883, vol. xxiii., N. S., pp. 597-609. Beitriige zur Anatomie der Asteriden, Zeitschr. f. wiss. Zool., Bd. xxx. pp. 99-131. 1 3 4 5 6 Sur l’ Appareil circulatoire des Etoiles de Mer, Comptes rendus, 1882, t. xciv. pp. 658-660. REPORT ON THE CRINOIDEA. 407 There is strong reason to believe that the “ovoid gland” of an Urchin or Starfish does not communicate with the exterior through the madreporite as described by Perrier, while there can now be no question respecting its direct connection with what has been generally described as the oral blood-vascular ring of these types. Koehler’s observations’ have demonstrated this connection in the Urchins, although it was categorically denied by Perrier.” It thus seems probable that although the “ ovoid gland” can no longer be described as a heart or even as a plexus of interlacing vessels, yet that it is a glandular structure interpolated in the blood-vascular system, and possibly one of the factories of the well known respiratory pigment of the Echinoderms. The following remarks by Welldon’ are noteworthy in connection with this subject :— “It is not too much to say that in every group of Invertebrates in which the vascular system has been at all carefully investigated, glandular appendages to the vessels have been found, which can, from their anatomical relations, have no other function than that of elaborating some of the constituents of the blood... .. In Echimoderms, the abundance of glandular cells in the cardiac plexus is probably a principal cause of the whole organ being regarded by many observers as an excretory apparatus.” NOTE G. (Page 119.) THE Nervous SYSTEM OF THE CRINOIDEA. Since the section on the nervous system was written (ante, pp. 111-127), the subject has been still further discussed by various morphologists, most of whom, I am glad to say, have adopted the views advanced therein, and have strengthened them very considerably. As in so many other cases, it appears that the doctrine of the nervous nature of the axial cords in the skeleton of a Crinoid is not of such recent growth as has been supposed. For the following passage from von Schlotheim* would seem to show that a nervous function was attributed to the contents of the central canal of the skeleton more than sixty years ago:—‘“ Da die Encriniten aber simmtlich mit einer durch alle Zweige laufenden Nervenrohre versehen sind, ud das Thier wenn es gleich mit der Wurzel angewachsen zu sein scheint, doch mit allen seinen festen Theilen beweglich bleibt, so gehért er offenbar nicht zu der Corallenarten, und macht nur ein merkwiir- diges Verbindungsglied zwischen der Classe der Crustaceen und der Zoophyten aus.” A general, and, on the whole, tolerably accurate account of the morphology of living Crinoids was published by Weinberg ° in the course of last year (1883). It is principally 1 Op. cit., p. 65, pl. 3, fig. 13. 2 Archives de Zool. expér., vol. iv., 1875, p. 613. 3 On the Head-Kidney of Bdellostoma, with a suggestion as to the origin of the Suprarenal Bodies, Quart. Journ. Mier. Sci., vol. xxiv., 1884, N. S., pp. 180, 181. + Die Petrefactenkunde, Gotha, 1820, p. 327. 5 Die Morphologie der lebenden Crinoideen mit Beziehung auf die Form Antedon rosacea, Linck, Der Naturhis- toriker, 5 Jahrg. Marz—Juni Heft, 1883, pp. 266-307. 408 THE VOYAGE OF H.M.S. CHALLENGER. a summary of the researches of his predecessors, though he states that he has himself made some observations on Antedon rosacea at the Zoological Station at Trieste. It was perhaps not to be expected that he should have done otherwise than propagate the orthodox German view respecting the nervous system. But the account which he gives of the position in 1883 of the doctrine that the axial cords are nerves, is an extremely inadequate one. He states (p. 283) that it has been proved to be incorrect by Greetf; while a few pages further on (p. 290) he says that attempts have been made to support it by the supposition (Annahme) that fine branches proceed from the axial cords to the muscles and arm-segments—“ Ludwig und Greeff wiesen jedoch das Unzuliinglche und Unrichtige der von Carpenter angefiihrten Argumente nach.” He then refers to the experiments performed by Dr. Carpenter, and leaves the question for further investiga- tion. Now, in the first place, the only comment which Greeff has made upon the doctrine that the axial cords are nerves has been a simple denial of its truth, without any attempt to discuss the subject at all;! and yet this denial is referred to by Weinberg as a proof of the doctrine being incorrect ! Ludwig, on the other hand, admits that the experimental evidence seems to afford very considerable support to Dr. Carpenter’s views ;” but he declines to accept them on account of the morphological difficulties which they involve. He has been unable to find the muscular branches from the axial cords which have been described by Dr. Carpenter and myself, and more recently by Perrier, Marshall, and Jickeli. But this does not justify Weinberg in stating that Ludwig has proved the arguments advanced by Dr. Carpenter and myself to be insufficient and incorrect; nor that the existence of these branches is merely a supposition. The fact that they were overlooked, not only by Teuscher and Greeff, but also by Ludwig and Weinberg, even after I had specially called attention to them, is no proof of their non-existence. Two figures of arm- sections, showing these branches, together with a further discussion of the whole question, were published in my paper’ On the Minute Anatomy of the Brachiate Echinoderms, which appeared two years before Weinberg wrote his résumé, but is not referred to by him at all. Another point of considerable interest in its bearings on this question is left entirely unnoticed by Weinberg, though it was fully explained in a paper* which he quotes, and it was illustrated by a diagram which also shows the branches of the axial cords ; although, according to Weinberg, the existence of these branches is a mere supposition. I refer to the frequent absence of the ambulacral nerve on more or fewer of the arms of Actino- metra. Weinberg admits its absence on the oral pinnules of Antedon, for this was 1 Ueber den Bau der Crinoideen, Sitzwngsb. d. Ge8ellsch. 2. Beford. d. gesammt. Naturwiss. zu Marburg, Nro. 1, 1876, pp. 21, 22. 2 Crinoideen, loc. cit., p. 335. 3 Quart. Journ. Mier. Sci., 1881, vol. xxi., N. S., pp. 188-192. 4 Remarks on the Anatomy of the Arms of the Crinoids, part ii., Journ. Anat. and Phys., vol. xi., 1876, pp. 90-93. a | REPORT ON THE CRINOIDEA. 409 discovered by Ludwig, whose observations he could not very well overlook. But he does not attempt to discuss the bearings of this fact on Ludwig’s doctrine that the axial cords are the only nerves in the arm of a Crinoid. He likewise describes the regular alternat- ing movements of the arms of a swimming Comatula, and the muscles by which these movements are effected ; and he leaves it to be inferred that these muscles are under the control of the only nervous system of which he admits the existence, although experi- ments have clearly proved that this is not the case; while Ludwig has admitted that he could trace no branches proceeding to the muscles from the ambulacral nerve. As to this last pomt, however, Weinberg is altogether silent. Until this present year no German morphologist, with the exception of Weinberg, had published any observations upon the Crinoids since the appearance of Ludwig’s important work in 1877; and the authors of zoological text-books published in Germany have confined themselves with remarkable unanimity to reproducing Ludwig's asser- tions that the nervous system of a Crinoid is essentially similar to that of an Asterid, and is limited to the fibrillar bands beneath the ambulacra. Dr. Carpenter’s views, if mentioned at all, which was rare, were regarded as untenable from their being altogether at variance with the established scheme of Echinoderm morphology. Claus, for example, describes the arrangement of the axial cords in the calyx in some detail, but says not a word about their functions ; while their presence is not even mentioned by Gegenbaur. According to these writers, therefore, the nervous system of a complex and highly specialised type like Pentacrinus is exclusively represented by the subepithelial bands of the ambulacra and the oral ring which unites them beneath the peristome (Pl. LXIL., ,nr). The extreme insignificance of these structures in comparison with the rest of the organism cannot fail to strike any one who examines the sections of the ambulacra represented on Pl. LVII.; and yet, according to the orthodox German morphology, they are the only nerves which a Crinoid possesses. The theory that the axial cords are nerves has recently been restated by Dr. Carpenter,’ with the additional support of a quantity of new facts which had been discovered since he last wrote on the subject, more than eight years ago. He concluded by saying, “those who refuse to accept them (my views) are bound, I think, either to disprove the facts, or to show that my deductions from them are unsound.” Within a very short time after the presentation of this communication to the Royal Society, two papers were published on the nervous system of the Crinoids, in which Dr. Carpenter's theory was unreservedly adopted and strengthened by a large body of additional evidence. The second of these, by Professor A. Milnes Marshall,? will be best considered first. After a short historical sketch of the subject, he describes an elaborate series of experi- ? On the Nervous System of the Crinoidea, Proc. Roy. Soc. Lond., vol. xxxvii., 1884, pp. 67-76. ® On the Nervous System of Antedon rosaceus, Quart. Journ. Micr. Sci., vol. xxiv., N. 8., 1884, pp. 507-548, pl. xxxv. (ZOOL. CHALL, EXP,—PART XXX11.—1884.) Ti 52 410 THE VOYAGE OF H.M.S. CHALLENGER. ments which have led him to the following conclusions :—‘ 1. The central capsule and its prolongations, the axial cords and their branches, constitute the main nervous system of Antedon. 2. The central capsule is specially connected with the complex co-ordinated movements of swimming and of righting when inverted. 3. The axial cords act as both afferent and efferent nerves. 4. The subepithelial bands are probably also nerves, but their exact function, probably a special and subordinate one in connection with the ambulacral tentacles and epithelium, is not yet ascertained.” These conclusions are the result of a long series of experimental investigations, in which Dr. Carpenter’s fundamental observations were repeated.and largely extended. Marshall’s paper concludes with a valuable discussion of the morphological aspect of his results. Starting from the generally accepted doctrine that the Asterids are the most primitive group of the Echinoderms, he shows how this character is well illustrated by their nervous system. Hamann’s observations have demonstrated that this “ is in the form of a continuous nerve-sheath enclosing the whole body, and directly continuous with the external epidermis of which it forms the deepest layer. This nerve-sheath is thickened at certain places, notably along the ambulacral grooves, where it forms the five radial or ambulacral nerves.” Marshall points out that the analogies of the Coelenterates, Cheetognatha, and Palzeonemertines all tend to show the primitive nature of the Asterid nervous system.' There is no difficulty about the relation of the nervous system of the remaining Echinozoa to that of the Asterids; but the case is different with the Crinoids, on account of the antambulacral position of their principal nerve centre and its radiating extensions. Marshall, however, is inclined to consider them as ‘descended from forms which agreed with the recent Asterids in possessing a complete nerve-sheath (though possibly very unlike Asterids in other respects) ;” and he is therefore “ disposed to regard the antambulacral nervous system of a Crinoid, 2.e., the central capsule and axial cords with their branches, as being derived from the antambulacral part of the primitive nerve- sheath, and not as an entirely new set of structures possessed by no other Echinoderms.” He endeavours to show that the relations of the axial cords which lie in grooves on the surface of the radials of the Pentacrinoid larva (a permanent condition in some Paleeocrinoids) are ‘“‘ very similar to those of the ambulacral nerves of an adult Ophiurid or Echinid, and as the latter have certainly acquired their adult condition by becoming detached from the epidermis and shifting inwards, so also may the same process be supposed to have occurred in the Crinoid.” Too much weight must not be laid upon this point, however, for the supposed inward movement of the radial nerves of an Ophiurid or Echinid would be from the outer or ambulacral surface of the plate towards the inner one, 2.e., that next to the body-cavity. On the other hand, in the developing Crinoidal calyx the axial cords are at first on the walls of the body-cavity, which are formed by the nner surfaces of the radials; but they 1 Compare Chapter VI. pp. 113, 115. | REPORT ON THE CRINOIDEA. 411 gradually come to lie in canals within the radials, and so are relatively (though of course not absolutely) nearer the epidermis on the exterior of the body, which in this case is antambulacral. The ontogenetic change in the relative position of the axial cords of a Crinoid is thus directly the opposite of that which Marshall supposes to have taken place phylo- genetically. On his theory the antambulacral portion of the primitive nerve-sheath should commence by being outside the radials, between them and the epidermis; whereas, as he himself admits, the radials are at first in the form of “calcareous plates between the cords and the integument.” His argument is, therefore, only one of analogy, and the outward movement of the axial cords in the Crinoid larva is not comparable morphologically to the inward movement, which must have taken place during the develop- ment of the radial nerve of an Urchin from the primitive nerve-sheath of a Starfish. It appears to me, however, that there is a possible view of the phylogeny of the axial cords which would not conflict in this way with their ontogenetic movement. According to Gétte’s observations, the ciliated ambulacral epithelium of the Crinoids is ' so that the ambulacral nerve, derived from the cellular lining of the left peritoneal sac ; which is in such close relation with this epithelium, is endodermic in its origin. On the other hand, the axial cords of a larval Crinoid lie in the walls of the dorsal portion of the body-cavity, which is lined by an epithelium derived from that of the right peritoneal sac ; and I would therefore suggest that the embryonic axial cords might have the same primitive relation to this epithelium as the ambulacral nerves must have to that of the left peritoneal sac, if Gétte’s observations be correct. The outward movement of the cords during development, away from the epithelium of the body-cavity, would then be, so to speak, serially homologous with the supposed inward movement of the ambulacral nerves of an Urchin. In other words, the axial cords are the nerves of the right antimer, while the subepithelial bands of the ambulacra are those of the left antimer, both being derived in the first instance from the epithelium of the enterocoel. In the Neocrinoids the axial cords eventually come to be some little distance from this epithelium; though they must have remained close to it in those Paleeocrinoids which had imperforate radials, just as they are in the Pentacrinoid larva. A variation of the same nature, though of course altogether different in degree, presents itself in the relation of the ambulacral nerve in certain species of Neocrinoids. I refer to the presence or absence of a delicate connective tissue lamella between the nerve and the overlying epithelium. This layer is often very conspicuous in Antedon eschrichti, but occasionally seems to be absent; while its presence in Antedon rosacea is doubtful. I have never satisfied myself of its existence in any other species, though Ludwig and Marshall 2 seem to quote me as having noted its occurrence in Actinometra. Ludwig* long ago 1 Archiv. f. mikrosk. Anat., Bd. xii. pp. 591-593. 2 Beitriage zur Anatomie der Crinoideen, Nachricht. v. d. kgl. Gesellsch. d. Wiss. zw Gottingen, No. 5, 1876, p. 108. 412 THE VOYAGE OF H.M.S. CHALLENGER. suggested that the great development and calcification of this lamella would bring the ambulacral nerve into a position corresponding to that of the radial nerve-cords of Ophiurids and Echinids. Marshall’ has recently put forward a somewhat similar hypothesis, viz., that this lamella “probably represents the earliest stage in the process by which the nerve becomes detached from the epidermis and shifted inwards.” We know far too little, however, about the ontogeny of the Echinoderm nervous system to do more than speculate on this subject. According to Selenka and Ludwig the nervous system of Asterids and Holothurids is of ectodermic origin ; while Gotte’s observations lead to the conclusion that the ambulacral nerves of Crinoids are derived from the endoderm. Should this really be the case, there can be no difficulty in taking the same view respecting the axial cords.” But even then we get no clue to the morphology of the central capsule, as Marshall has conveniently called the fibrillar envelope of the chambered organ in which the axial cords originate. He remarks’ that “ Dr Carpenter’s observations lead to the belief that, at any rate in its present form, it is connected with the change from the pedunculate to the free- swimming condition ; and it is worthy of notice that the two actions with which it has been found to be specially concerned physiologically, z.e., the movements of swimming and of righting, are ones that the pedunculate form, from the very nature of things, can never exercise.” I cannot quite share Marshall’s belief in the relation between the central capsule and the change from the attached to the free mode of life. The only difference between the chambered organ of a Comatula and that of a Stalked Crinoid is the absence of any cirrus-vessels in connection with the latter ; for these come off from the peripheral vessels of the stem (Pl. XXIV. fig. 4; Pl. LXII.—cv), which are the downward extensions of the cavities of the chambered organ. But the central capsule or fibrillar envelope of these cavities, which in Comatula “is specially connected with the complex co-ordinated move- ments of swimming and of righting when inverted,” is equally present in all the Stalked Crinoids (Pl. VIIb. fig. 2; Pl. XXIV. figs. 6, 7; Pl. LVIII. figs. 1,3; Pl LXII°); and there can be no doubt that it controls the movements of flexion and extension of the arms. The latter of these is essential to the proper nutrition of the animal; and I can quite believe that the arms may also be used for swimming by those Pentacrinidee, such as Pentacrinus maclearanus, Pentacrinus alternicirrus, and Pentacrinus wyville-thomsoni, which have short stems terminating below at a nodal jomt (Pl. XVI. fig. 1; Pl. XIX. fig. 1). In all the Stalked Crinoids the central capsule is continued downwards into the stem as a sheath around the central vascular axis (Pl. VIIa. figs. 1, 2; Pl. XXIV. figs. 1-6; Pl. LXII.—ca), and it gives off branches which spread out towards the surface of the stem, 1 Loe. cit., p. 546. * Whatever be the origin of these cords, they are essentially mesodermic in their distribution ; and it isin this sense that I have spoken of them in the text as constituting a mesodermic nervous system (p. 114). 3 Loe. cit., p. 547. REPORT ON THE CRINOIDEA. 4138 and probably form a subepidermic plexus (Pl. VIIa. fig. 1; Pl XXIV. fig. 2—cq’). Extensions of it also proceed into the cirri round the cirrus-vessels (Pl. LXIL., ev), and give off similar radiating branches. Jickeli’s observations on Antedon rosacea show that the movements of the cirri, like those of the arms, are dependent upon an influence pro- ceeding from their axial cords ;* and it is clear that if the central capsule and axial cords of Comatula constitute its principal nervous system (as few will now deny), this must be regarded as also extending throughout the whole stem of a Stalked Crinoid, even though it reach 70 feet in length, as in the fossil Hxtracrinus subangularis. It may also be assumed with tolerable certainty that there was a similar neuro- vascular axis in the stem of all the fossil Pelmatozoa, including the Blastoids. These had no arms attached to the radials, as a Crinoid has. ment of axial cords in the basals and radials as prevail in a Crinoid, which [ see no reason to doubt, it is unlikely that the radial cords, starting from the circular commissure (fig. 20, A) should have ended in the forks of the radials which receive the distal ends of - the ambulacra. In the Mesozoic Phyllocrinus the radials have almost exactly the same forked shape as those of a Pentremites; but the point where the limbs of each fork separate is marked by an articular facet to which the arm was attached. In a Blastoid, however, the sinus between the two limbs of the radial is filled wp by the ambulacrum, which terminates in a more or less prominent lip at the same point in the body of the radial as is occupied by the articular facet in Phyllocrinus. That the axial cord in.the radial of a Pentremites (fic. 20, A) ended in this lip seems to me improbable; and I cannot help suspecting that it may here have become continuous with the nerve of the ambulacrum. From what we know of the But if they had the same arrange- \\ ( MN Pa f il ambulacral nerves of recent Crinoids, this is not likely per se to have been related to any other movements but those of the tentacles, even if these organs were present ; while it may ar perhaps have been removed from the superficial epithelium, as Fic. 20.—Diagram showing the in an Urchin, and lodged within one of the canals in the lancet plate. This would have brought it deep enough to be continuous with the axial cord of the radial at the termination of the ambulacrum. The movements of the so called pinnules of the Blastoid would thus have been controlled by the central capsule, instead of by the oral ring, which is not likely to have had anything to do with them; for the oral ring of a recent Crinoid has absolutely no control over the movements of any part of the arrangement of the axial cords in the calyx of a Pentremites, supposing it to be the same as in the calyx of a Crinoid. The pinnules are represented as preserved on one ambulacrum, Bat not on the other. A, axial cord of the ray; a, primary interradial cord ; a7, one of the converging radial cords which result from its bifurcation; B, basal; cco, circular com- missure; J, interradial plate (deltoid of Roemer) ; 2, radial. calcareous skeleton; and the jointed pinnules of a Blastoid cannot have remained permanently closed over the ambulacra, as they are found in the fossils (fig. 20). 1 See the quotation from Agassiz, ante, p. 333. 414 THE VOYAGE OF H.M.S. CHALLENGER. Lovén has recently pointed out the singularly Crinoidal appearance of the calycinal system of a Triassic Urchin, Tiarechinus princeps, Laube.! “The relative magnitude of the entire system, the prominent share it takes among the constituents of the skeleton, the forms and proportions of its parts, are such as forcibly to recall the calyx of some Palxocrinoid, and to justify a desire to turn the Echinoid upside down and to see the Fic. 21.—Tiarechinus princeps, Laube, inverted so as to show the resemblance of its apical system to the calyx of a Crinoid. (The figure, but not the letters, after Lovén.) B, basal; 7, single, median interradial ; 7, lateral interradials; R, radial. calycinal system in its imaginary original position, when it formed a part of some remote ancestral type. In this respect the resemblance becomes still more striking.” Let us compare Lovén’s figure (fig. 21) with that of the Blastoid (fig. 20). Each has relatively large basals (B) ; but the radials of the Pentremite (2) are small in Tiarechinus, their limbs being replaced by the two lateral plates of the interradius (7) which enclose the ambulacrum. In Tiare- chinus, just as in the Blastoid, however, the ambulacrum ends against the body of the corresponding radial ; and its nerve, lying beneath the ambulacral plates as in recent Echini, would be in a position where it could be directly continuous with an axial cord situated within the radial or on its inner face, if only Tiarechinus were a Crinoid instead of an Urchin. I would not, of course, be understood as saying that Tiarechinus had a central capsule and axial cords pro- ceeding from it. My only object has been to point out that Lovén’s happy comparison of this curious type with an inverted Crinoid affects other systems of organs besides that of the calycular plates. At the same time, considering the number of Asterids which have a calyx of relatively large plates, and the fact that there is a continuous nerve sheath on the dorsal surface, I think it not improbable that indications of a central capsule and axial cords may eventually be discovered in the Echinozoa. It remains now to notice the observations of Dr. Jickeli, which, though only published recently, are nearly four years old.” Like Marshall he has made an elaborate series of experiments in extension and confirmation of those originally described by Dr. Carpenter, whose views respecting the nervous nature of the central capsule and axial cords he adopts unreservedly. He further believes that the fibrillar bundles uniting the cirrus- joints and those forming the dorsal and interarticular ligaments (as they are described above) in the arms (Pl. LXIL., /d, 7’) are muscular in function, though differing in many points from the fibres. which have hitherto been exclusively described as muscles (Pl. LXII., m); for when the axial cord of a detached cirrus is stimulated “so kriimmt sich derselbe auf das Heftigste zusammen und geriith selbst in Tetanus. 1 On Pourtalesia, loc. c2t., p. 65. 3 2 Vorliufige Mittheilungen iiber den Bau der Echinodermen, ], Ueber das Nervensystem und die Sinnesorgane der Comatula mediterranea, Zool. Anzeiger, vii. Jahrg., pp. 346-349 and 366-370, 1884. 5 Zool. Anzeiger, vol. vii., 1884, p. 348. REPORT ON THE CRINOIDEA, d 415 This seems to indicate clearly that the interarticular fibres of the cirri are muscular in function, though not striated like the ventral fibres which unite the arm-joints, and have hitherto been regarded as the only true muscles of the Crinoid organisation. Four years ago I pointed out that the appearance of some of my sections had led me to think that the axial cord of the arm consisted of two lateral fibrillar masses enclosing a central structure." According to Jickeli? this last is a longitudinal septum between two tubes which contain blood-corpuscles; while the whole structure is enclosed in a sheath of nervous tissue. Within the calyx the tubes of the different rays unite laterally and “gehen durch eben solche das gekammerte Organ theilweise bedeckende Fortsitze in ein spongidses Geflecht tiber, welches dem gekammerten Organ wie eine Kiippe aufsitzt. Von diesem spongidsen Geflecht entspringen die Fortsetzungen in die Cirrhen. Die Wandung dieses Réhrensystems ist die nervése Substanz, die Masse, welche dasselbe erfiillt, besteht aus geronnenem Plasma, in welches Blutzellen einge- backen sind.” It does not appear, however, that these axial blood-tubes are in any way connected with the cavities of the chambered organ. Jickeli poimts out that his observations confirm the statements of Miiller? respecting the presence of a blood- vessel within the central canal of the arms, which subsequent workers have generally considered to be erroneous. He finds that the elements of the nerve sheath surrounding these blood-vessels are most easily demonstrated in the radial axillaries where the axial cords of two arms unite, and he describes the presence of ganglionic cells with from two to six processes, some of which unite with those of other cells, He has also seen the muscular branches of the axial cords, the existence of which, according to Weinberg, is only a supposition ; and by the use of polarised light he has traced these into the dorsal as well as into the ventral musculature. He doubts the presence of a definite oral ring in the ambulacral nervous system. For he finds that the ventral nerves extend down into the fore-gut beneath its epithelium, which is directly continuous with that lining the food-grooves. The appear- ance of several of my sections, both of Pentacrinus and of Comatula, has led me to suspect this fact; but I have hesitated to say so, as I wished to verify it by making some sections of individuals which had been properly prepared for histological work. This having been done by Jickeli, I am glad to be able to confirm his observations. He believes himself to have discovered yet another nervous structure in the Crinoid organisation, “es ist noch ein drittes bis dahin nicht bekanntes, im Bindegewebe gelagertes Nervencentrum vorhanden, welches die Mundéffnung umgibt, und die radialen Wasser- gefiisse jederseits als ein gesonderter, an die Tentakeln in regelmissigen Abstiinden Zweige abgebender Strang begleitet.”* The peripheral parts of this system appear to me to belong to what I have called the parambulacral network, situated in the ventral * Quart. Journ. Mier. Sci., 1881, vol. xxii., N. S., p. 187. 2 Zool. Anzeiger, vol. vii. p. 368, 1884. § Bau der Pentacrinus, loc. cit., p. 22. 4 Zool. Anzeiger, vol, vii. p. 370, 1884. 416 THE VOYAGE OF H.M.S. CHALLENGER. perisome of the arms and disk. Jickeli says, for example, “ von diesem dritten Nerven- centrum gehen auch starke Zweige in die ventrale Korperhaut und losen sich dort in feine nervose Geflechte auf.”! It will be strange indeed if these prove to be anything else than the ramifications of the ventral branches of the axial cords of the arms which I described long ago as extending to the edges of the food-groove (see fig. 4, p. 113; fig. 5, p- 121; and fig. 8, p. 123). I cannot say, however, that I have ever seen the pentagonal ring round the mouth which Jickeli mentions, nor even its radial extensions at the sides of the water-vessels ; unless indeed these last be the lateral trunks which I have described above in Actinometra nigra, from sections now nearly nine years old (p. 122). The branches of Jickeli’s third nervous system which break up into a plexus in the ventral perisome appear to me to be identical with those which I described two years ago as extending along the sides of the ambulacra of Antedon eschrichti from the edge of the disk to the neighbourhood of the mouth.’ A diagrammatic representation of them is given on p. 123, while illustrations of single sections, both of this species and of Penta- crinus decorus, are shown on Pl. LIX. figs. 2-7. These branches are unquestionably of the same nature as those occupying a similar position in the arms (Pl. LX. fig. 6, a’), and belong like them to the system of the central capsule and axial cords, with which last they are connected at the edge of the disk. But at the same time I fully believe that they are the peripheral portions of the third nervous system described by Jickeli. The so called papille of the tentacles have also attracted his attention, and he regards them as sense-organs of a somewhat complicated nature, supporting fine sensory hairs. He thus inclines to Perrier’s view of the nature of these papille rather than to that of Ludwig, who regards them as glandular organs. Jickeli, however, describes them as being innervated by the branches of his third nerve-centre ; while according to Perrier® they receive nerve-fibres from the ventral branches of the axial cords, which form what I have called the parambulacral network. But if I am right in identifying this with the peripheral part of Jickeli’s third nervous system, his observations are completely in étccordance with those of Perrier. 1 Zool. Anzeiger, vol. vii. p. 369, 1884. 2 Quart. Journ. Mier. Sci., 1883, vol. xxiii., N.8., p. 615. 3 Comptes rendus, t. xcvii. p. 188. BIBLIOGRAPHY OF THE NEOCRINOIDEA. The following list does not pretend to be a complete Bibliography of the Neocrinoidea, i.c., to give a reference to every description of a fossil Crinoid which has appeared in the countless publications upon the Paleontology of the Secondary and Tertiary Periods. Neither is it meant to include every notice of a recent Crinoid in faunal and other lists. The numerous controversial references to fossil forms in epistolary communications to the Neues Jahrbuch by von Buch, von Meyer, and others are also mostly omitted, and must be sought for in the excellent Bibliography of de Koninck and le Hon. But I have endeavoured to make the accompanying list complete for the two following classes of works :—(1) all those containing descriptions of new species of recent Crinoids; (2) all those which, though dealing principally with Paleocrinoids or with other Echinoderms, contain valuable information upon the Morphology of the Crinoids generally. The literature of the Pelmatozoa has increased at a very rapid rate since the publication of the admirable Bibliography by de Koninck and le Hon in 1854, which contained a chronological list of nearly all the earlier works on the subject." We may hope ere long for a supplement to this as regards the Paleeocrinoids from Messrs. Wach- smuth and Springer; and I trust in the course of time to be able to complete the following list by the addition of references to works on general paleontology which contain notices of Neoerinoids. Avams, J., Description of some Marine Animals found on the Coast of Wales. Z'rans. Linn. Soc. Lond., vol. v., 1800, pp. 7-13, Tab. ii. Agassiz, A., Note on Lovén’s article on Leskia mirabilis, Gray. Ann. Lyceum Nat. Hist., vol. ix. pp. 242—- 245, New York, 1869. Revision of the Echini. ll. Cat. Mus. Comp. Zoil., No. 7, Cambridge (U.S.), 1872-74, xii + 762 pp-, 94 pls., 69 cuts. North American Starfishes. Mem. Mus. Comp. Zoil., vol. v., No. 1, 1877, iv + 136 pp., 20 pls.* Drawing of Young Holopus from Bahia Honda, Cuba. Bull. Mus. Comp. Zodl., vol. v., No. 9, 1878, p- 213. Selections from Embryological Monographs. II. Echinodermata. dem. Mus. Comp. Zobl., vol. ix., No. 2, 1883, 45 pp., 15 pls. Bibliography in Bull. Mus. Comp. Zoil., vol. x., No. 2, 1882, pp. 109-134. 1 [ have come across a few morphological papers which are not noticed by de Koninck and le Hon, and have recorded them in the following list. (ZOOL, CHALL. EXP.—PART XxxiI.—1884.) Ti 53 418 THE VOYAGE OF H.M.S. CHALLENGER. Agassiz, A., Reports on the Results of Dredging under the Supervision of Alexander Agassiz, in the Gulf of Mexico (1877-78), in the Caribbean Sea (1878-79), and along the Atlantic Coast of the United States (1880), by the U.S. Coast Survey steamer “Blake,” Lieut.-Commander C. D. Sigsbee, U.S.N., and Commander J. R. Bartlett, U.S.N., commanding—XXIV., Part L, Report on the Echini. Mem. Mus. Comp. Zobl., vol. x., No. 1, 1883, viii + 94 pp., 32 pls. Acassiz, L., Prodrome d’une Monographie des Radiaires ou Echinodermes. Mem. Soc. Sci. Nat. Neuchatel, vol. 1., 1835, pp. 168-199. ——— Twelve Lectures on Comparative Embryology, delivered before the Lowell Institute in Boston. Boston, 1849, 104 pp. Atiman, G. J., On a Pre-Brachial Stage in the Development of Comatula, and its importance in relation to certain Aberrant Forms of Extinct Crinoids. Trans. Roy. Soc. Edin., vol. xxiii, 1864, pp. 241-252, pl. xii. Abstract in Rep. Brit. Assoc., 1862, Trans. Geol. Sect., p. 65. Axonymous, Notes and Observations on Injured or Diseased Crinoids. Proc. Nat. Hist. Soc. Glasgow, vol. iii., 1876, pp. 91-94. Austin, T., Proposed Arrangement of the Echinodermata, particularly as regards the Crinoidea, and a subdivision of the class Adelostella (Echinide). Ann. and Mag. Nat. Hist., ser. 1, vol, x., 1842, pp. 109-103. Observations on the Cystidea of M. von Buch, and the Crinoidea generally. Journ. Geol. Soc., vol. iv., 1848, pp. 291-294. — Observations on the connection between the Crinoidea and the Echinodermata generally. Ann. and Mag. Nat. Hist., ser. 2, vol. viii., 1851, pp. 280-290. Austin, T., and T. Austin, jun., A Monograph on Recent and Fossil Crinoidea, 128 + xvi pp., 16 pls. (ull published). Bristol, 1843-45, Batty, W. H., Description of a new Pentacrinite from the Kimmeridge (cf. Oxford) Clay of Weymouth, Dorsetshire. Ann. and Mag. Nat. Hist., ser. 3, vol. vi., 1860, pp. 25-28, pl. i. Batrour, F. M., A Treatise on Comparative Embryology, vol. i., London, 1880. Echinodermata in chap. xx. pp. 453-481. Baupe or, E., Etudes générales sur le systtme nerveux. Contribution & Vhistoire du systtme nerveux des Echinodermes. Archives d. Zool. expér., t. i., 1870, pp. 177-216. Bett, F. J., An Attempt to apply a Method of Formulation to the Species of the Comatulide, with the description of a new species. Proc. Zool. Soc. Lond., 1882, pp. 530-536, pl. xx. Note on a Crinoid from the Straits of Magellan. Proc. Zool. Soc. Lond., 1882, pp. 650-652, with cut. Report on the Zoological Collections made in the Indo-Pacific Ocean during the Voyage of H.M.S. “ Alert,” 1881-82. Crinoidea in pp. 153-170, pls. x.-xvii., London, 1884. Bryricu, E., Ueber die Crinoideen des Muschelkalks. Abhandi. d. k. Akad. d. Wiss. Berlin., Phys. K1., Nr. 1, pp. 1-49, Taf. i., ii. Eugeniacrinus. Zeitschr. d. deutsch. geol. Gresellsch., Bd. xxi., 1869, p. 835. Protocoll der Sitzung vom 15 Sept. 1869. Ueber die Basis der Crinoidea brachiata. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1871, pp. 33-55. Bitines, E., On the Cystidez of the Lower Silurian Rocks of Canada. Figures and Descriptions of Canadian Organic Remains. Decade III., 1858, pp. 9-74, pls. i—vil. On the Crinoidez of the Lower Silurian Rocks of Canada. Figures and Descriptions of Canadian Organic Remains. Decade IV., 1859, pp. 7-66, pls. i—x. Note on Leskia mirabilis, Gray, by 8. Lovén, communicated by C. F. Liitken. Canad. Nat., N.'., vol. 1i1., 1868, pp. 442-445, 5 figs. Note on Hyponome Sarsi, described by S. Lovén, by C. F. Liitken. Canad. Nat., N.S., vol. iv., 1869, p. 270. Notes on the Structure of the Crinoidea, Cystidea, and Blastoidea. Amer. Journ. Sci. and Arts, vol. xlviii., 1869, pp. 69-83 ; vol. xlix., 1870, pp. 51-58; vol. 1, 1870, pp. 225-240. Reprinted in the Ann. and Mag. Nat. Hist., ser. 4, vol. v., 1870, pp. 251-266, and 409-416 ; vol. vii., 1871, pp. 142-158. ~ REPORT ON THE CRINOIDEA. 419 3LainvILLE, H. M. D. ps, Manuel d’Actinologie ou de Zoophytologie. Paris, 1834, viii+694, pp. 100 pls. Crinoids in pp. 247-265 ; pls. xxvi-xxix. Boutscun, W., Ueber Actinometra Bennettii und eine neue Comatula-Art (Antedon Dubenii). Archiv /. Naturgesch., Bd. xxxii., 1866, pp. 90-92. Brony, H. G., Ueber die Krinoiden-Reste im Muschelkalk. Neues Jahrb. f. Mineralogie, Jahrg. 1837, pp. 30-33, Taf. ii. . Brony, H. G., and Rosmer, F., Lethxa geognostica, oder Abbildung und Beschreibung der fiir die Gebirgs- Formationen bezeichnendsten Versteinerungen. » Dritte Auflage, Theil v, Bd. ii-iii., Mesolethza, Stuttgart, 1851-52. Die Klassen und Ordnungen des Thier-Reichs, Bd. ii, (Aktinozoen). Leipzig and Heidelberg, 1860, 434 pp., 49 pls. and cuts. Busou, W., Ueber die Larve der Comatula. Archiv f. Anat. Physiol. u. wiss. Med., Berlin, 1849, pp. 400-402 (Mit. Abbildgn). ——— Beobachtungen ueber Anatomie und Entwickelung einige Wirbellosen Seethiere. Berlin, 1851, 143 pp., 17 pls. Carpenter, P. H., Remarks on the Anatomy of the Arms of the Crinoids. Journ. Anat. and Physiol., vol. x., 1876, pp. 571-585, 2 cuts. —_—— Remarks on the Anatomy of the Arms of the Crinoids, part. ii. Journ. Anat. and Physiol., vol. xi., 1876, pp. 87-95, with cut. On some Points in the Anatomy of Pentacrinus and Rhizocrinus. Journ. Anat. and Physiol., vol. xii., 1877, pp. 35-53. —— — On the genus Actinometra, Miill., with a Morphological Account of a new Species (Actinometra poly- morpha) from the Philippine Islands. Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. ii, 1879-84, part 1, pp. 1-122, pls. i—viii. Abstract in Journ. Linn. Soc. Lond. (Zool.), vol. xiii., 1877, pp. 439-456. Preliminary Report upon the Comatule of the Challenger Expedition. Proc. Roy. Soc., vol. xxviii., 1879, pp. 383-395. Notes on Echinoderm Morphology. No. I. On the Oral and Apical Systems of the Echinoderms, pti Quart. Journ. Micr. Sci., N.S., vol. xviii., 1878, pp. 351-383, 11 cuts. Note II. On the Apical and Oral Systems of the Echinodermata, pt. ii. Quart. Journ. Mier. Sei., N.S., vol. xix., 1879, pp. 176-206, 7 cuts. __.-_ Note ILI. Some disputed points in Echinoderm Morphology. Quart. Journ. Mier. Sci., N.S., vol. xx., 1880, pp. 321-329. Note IV. The Minute Anatomy of the Brachiate Echinoderms. Quart. Journ. Micr. Sci., N.S., vol. xxi., 1881, pp. 169-193, 2 pls. and 1 cut. Note V. On the Homologies of the Apical System, with some Remarks upon the Blood-Vescels. Quart. Journ. Mier. Sci., N.S., vol. xxii., 1882, pp. 371-386, 4 cuts. Note VI. On the Anatomical Relations of the Vascular System. Quart. Journ. Mier. Sci., N.S., vol. xxiii., 1883, pp. 597-616. Note VII. On the Apical System of the Ophiurids. Quart. Journ. Mier, Set., N.S., vol. xxiv., 1884, pp. 1-23, pl. i. Note VIII. On some points in the Anatomy of Larval Comatule. Quart. Journ. Mier. Sci., N.S., vol. xxiv., 1884, pp. 319-327, with cut. , On the Nomenclature of the Plates of the Crinoidal Calyx. Rep. Brit. Assoc., 1879, pp. 333, 334. The Nervous System of Comatula. Rep. Brit. Assoc., 1879, pp. 418, 419. The Chambered Organ of Comatula. Zool. Anzeiger, Jahrg. ii., 1879, pp. 569-571. Feather-Stars, Recent and Fossil. Popular Science Review, N.S., vol. iv., 1880, pp. 193-204, pls. v., vi. On some undescribed Comatule from the British Secondary Rocks. Quart. Journ. Geol. Soc., vol. xxxvi., 1880, pp. 36-55, pl. v. and cut. On some new Cretaceous Comatule, Quart. Journ. Geol. Soc., vol. xxxvi., 1880, pp. 549-558, pl. xxiii. On the Genus Solanocrinus, Goldfuss, and its Relations to recent Comatule. Journ, Linn. Soc. Lond. (Zool.), vol. xv., 1880, pp. 187-217, pls. ix.—xii. 420 THE VOYAGE OF H.M.8. CHALLENGER. Carpenter, P. H., On two new Crinoids from the Upper Chalk of Southern Sweden. Quart. Journ. Geol. Soc., vol. xxxvii., 1881, pp. 128-136, pl. vi. On a new Comatula from the Kelloway Rock. Abstract in Proc. Geol. Soc., No. 407,°1881, p. 98. On the Characters of the “Lansdown Encrinite” (Millericrinus Prattii, Gray, sp.). Rep. Brit. Assoc., 1881, p. 635. On some Permanent Larval Forms among the Crinoidea. Rep. Brit. Assoc., 1881, pp. 671, 672. Note on the European Comatulew. Zool. Anzeiger, Jahrg. iv., 1881, pp. 520-522. The Comatul of the Leyden Museum. 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M., On the Genera and Species of the British Echinodermata—Part. I. Crinoidea, Ophiuroidea, Asteroidea. Ann. and Mag. Nat. Hist., ser. 3, vol. xv., 1865, pp. 98-129, Orrstep, A. §., Descriptions of Pentacrinus caput-Meduse and of Pentacrinus miilleri. Férhandl. Skand. Naturf., 7°° Mode i Christiania, 1856, p. 202. WVOrsiany, A., Mémoire sur une seconde espéce vivante de la famille des Crinoides ou Encrines, servant de type au Nouveau genre Holope (Holopus). MJagas. de Zool., 7™* ann., Paris, 1837, Cl. x. pp. 1-8, pl. 3. Cours élémentaire de -Paléontologie et de Géologie stratigraphiqe, Paris, 1850-52, 3 vols. Prodrome de Paléontologie stratigraphique universelle des Animaux Mollusques et Rayonnées, Paris, 1850-51, 3 vols. Histoire naturelle générale et particulitre des Crinoides vivans et fossiles, comprenant la description Zoologique et Géologique de ces animaux, Paris, 1858, 97 pp. 18 pls. Pearce, J. C., On the Locomotive and Non-Locomotive Powers of the family Crinoidea. Proc. Geol. Soc. Lond., vol, iv., 1843, pp. 159, 160. Perrier, E., Recherches sur !’Anatomie et la Régénération des Bras de la Comatula rosacea (Antedon rosaceus, Linck.). Archives d. Zool. expér., t. ti., 1873, pp. 29-86, pls. ii.—iv. Note sur les Brisinga. Comptes rendus, t. xcv., 1882, pp. 61-63. Sur une Astérie des grandes profondeurs de |’Atlantique, pourvue dun pédoncule dorsal. Comptes rendus, t. xev., 1882, pp. 1379-1381. Sur un nouveau Crinoide fixe, le Democrinus Parfaiti, provenant des dragages du ‘‘'T'ravailleur.” Comptes rendus, t. xevi., 1883, pp. 450, 451. Sur des Eudiocrinus de Atlantique et sur Ja nature de la faune des grandes profondeurs. Comptes rendus, t. xevi., 1883, pp. 725-728. Echinodermes ; sur Porganisation des Crinoides. Comptes rendus, t. xevii., 1883, pp. 187-189. Sur le développement des Comatules. Comptes rendus, t. xevill., 1884, pp. 444-447. Anatomie des Echinodermes; sur l’organisation des Comatules adultes. Comptes rendus, t. xeviii., 1884, pp. 1448-1450. Mémoire sur les Etoiles de Mer recueillies dans la mer des Antilles et le Golfe du Mexique durant les expéditions de dragage faites sous la direction de M. Alexandre Agassiz. Nouv. Archiv. du Mus. d’Hist., Nat., sér. 2, t. vi, 1884, pp. 126-276, pls. i—x. Puruerr, R. A., Alecto alticeps, n. sp., eine tertiire Comatula-Art von Palermo, Newes Jahrb. f. Mineral., Jahrg. 1844, pp. 540-542. Picarp, K., Ueber eine neue Crinoideen-Art aus dem Muschelkalk der Hainleite bei Sondershausen. Zevtschr. d. deutsch. geol. Gesellsch., Jahrg. 1883, pp. 199-202, Taf. ix. Proret, F. J., Traité de Paléontologie, ou Histoire Naturelle des Animaux Fossiles considérés dans leurs Rapports Zoologiques et Geologiques, Seconde Edition, Paris, 1857. Crinoidea in t. iv. pp. 278-345, pls. xcix.—cil. Pourratis, L. F. pz, Contributions to the Fauna of the Gulf Stream at great Depths. Bull. Mus. Comp. Zool., vol. i., Nos. 6, 7, 1867-68, pp. 103-142. List of the Crinoids obtained on the Coasts of Florida and Cuba by the United States Coast Survey Gulf Stream Expeditions in 1867, 1868, 1869. Bull. Mus. Comp. Zodl., vol. i, No. 11, 1869, pp. 355-358. Zoological Results of the Hassler Expedition—Crinoids and Corals. Jil. Cat. Mus. Comp. Zoil., No. 8, 1874, pp. 27-52, pls. v.—x. PART XXx1I.—1884.) Ti 54 (ZOOL. CHALL. EXP. 426 THE VOYAGE OF H.M.S. CHALLENGER. ‘ Pourratis, L. F. pe, Reports on the results of Dredging, under the Supervision of Alexander Agassiz, in the Gulf of Mexico, by the United States Coast Survey steamer “ Blake,” Lieut.-Commander C. D. Sigsbee, U.S.N., Commanding—Crinoids. Bull. Mus, Comp. Zodl., vol. v., No. 9, 1878, pp. 214— 216. Description of a young Holopus, with two figures (pl. ii.), by A. Agassiz, on p. 213. Quenstept, F. A., Ueber die Encriniten des Muschelkalks. Archiv f. Naturgesch., Jahrg. i, 1835, Bd. ii. pp. 223-228, Tab. iv. Schwaben’s Medusenhaupt—Eine Monographie der Subangularen Pentacriniten, pp. 1-73, mit 1 grossen Tableau in 4 Blattern, Tiibingen, 1868. Petrefactenkunde Deutschlands, Bd. iv. Die Asteriden und Encriniden nebst Cysti- und Blastoideen. Nebst einem Atlas von 25 Tafeln, Leipzig, 1876, viii+742 pp. Rarueun, R., A List of the Brazilian Echinoderms, with Notes on their Distribution, &e. Trans. Connect. Acad., vol. v., 1879, pp. 139-158. Rerzivs, A. J., Anmarkningar vid Asteria Genus. Nya K. Svensk. Vetensk. Akad. Handl., Bad. iv., 1783, pp. 234-243, Dissertatio sistens species cognitas Asteriarum, Lund, 1805, 37 pp. Sars, M., Bemaerkninger over Brisinga endecacnemos, Asbjornsen, og Comatula Sarsii, Diib.et Kor. #érhandl. Skand. Naturf., 7° Mode i Christiania, 1856, pp. 209-211. Om Comatula Sarsii, Diib. et Kor., i fastsiddende eller Pentacrinus-tilstand. Grhandl. Skand. Naturf., 74 Méde i Christiania, 1856, pp. 212-216. Mémoires pour servir 4 la connaissance des Crinoides vivants, Christiania, 1868, 65 pp. 6 pls. Savieny, J. C., Explication sommaire des Planches @’Echinodermes de ’Egypte et de la Syrie, publiées par Jules-César Savigny ; offrant un Exposé des caractéres naturels des genres avec la distinction des Espéces, par Victor Audouin. Description de Egypte. Seconde Edition, t. xxiii., Paris, 1828. Histoire Naturelle, Zoologie. Crinoids in pp. 1-5, pl. i. Scuuirer, C., Ueber einige astylide Crinoiden. Zeitschr. d. deutsch. geol. Gesellsch., Jahrg. 1878, pp. 28-66, Taf. i-iv. Scuunrze, L., Monographie der Echinodermen des Eifler Kalkes. Denkschr. d. k. Akad. d. Wiss. Wien, Mat.- Naturwiss. Classe, Bd. xxvi., 1866, pp. 113-229, Taf. 1—xii. Semper, C., Kurze anatomische Bemerkungen iiber Comatula. Arbeit. aus d. Zool.-Zootom. Institut in Wiirz- burg, Bd. i., 1874, pp. 259-263, with cut. — Ophiocrinus, eine neue Comatuliden Gattung. Archiv f. Naturgesch., Bd. xxxiv., 1868, pp. 68, 69. Stapey, W. P., On the Homologies of the Primary Larval Plates in the Test of Brachiate Echinoderms. Quart. Journ. Mier. Sci., N. S., vol. xxiv., 1884, pp. 24-42, pl. i. Sreenstrup, J. J., Cyathidium holopus. Bericht wi. d. Versamml. deutsch. Naturf. in Kiel, 1846, p. 150. Sreuzner, Aup., Ein Beitrag zur Kenntniss des Versteinerungs-Zustandes der Crinoideenreste. Mewes Jahrb. 7. Mineral., Jahrg. 1864, pp. 565-579, Taf. x. Srrompeck, A. von, Ueber Missbildungen von Enerinus liliiformis, Lam. Paleontographica, Bd. iv., 1855, pp. 169-178, Tab. xxxi. Twuscuer, R., Beitriige zur Anatomie der Echinodermen—I. Comatula mediterranea. Jenaische Zeitschr. Bd. x., 1876, pp. 243-262, Taf. vii. Tuompson, J. V., Memoir on the Pentacrinus Europeus: a recent Species discovered in the Cove of Cork, July 1, 1823. Cork, 1827, 12 pp., 2 pls. Memoir on the Star Fish of the Genus Comatula, demonstrative of the Pentacrinus europeus being the young of ourindigenous species. Edin. New Phil. Journ., vol. xx., 1836, pp. 295-300, pl. ii. Abstract in Proc. Roy. Soc., 1835, p. 339. Tuomson, C. W., On a new Paleozoic group of Echinodermata. Edin. New Phil. Journ., vol. xiii, 1861, pp. 106-117, pls. iii., iv. Sea Lilies. he Intellectual Observer, vol. vi., No. 31, August 1864, pp. 1-11, with plate. On the Embryogeny of Antedon rosaceus, Linck (Comatula rosacea of Lamarck). Phil. Trans., vol. elv. 1865 pp. 513-544, pls. xxiii—xxvii. Abstract in Proc. Roy. Soc., vol. ix., 1857-59, pp. 600-601. REPORT ON THE CRINOIDEA. 427 Tuomson, C. W., On the Structure of the Paleozoic Crinoids. Abstract in Proc. Roy. Soc. Edin., vol. vii.’ 1869-72, pp. 415-418. ~. On the Crinoids of the “Porcupine” Deep-Sea Dredging Expedition. Proc. Roy. Soc. Edin., vol. vii., 1869-72, pp. 764-773. ve Notice of new Living Crinoids belonging to the Apiocrinide. Journ. Linn. Soc. Lond. (Zool.), vol. xiii., 1876, pp. 47-55, 5 cuts. uu Description of Pentacrinus maclearanus, in The Atlantic. London, 1877, vol. ii. pp. 123-126. On the Structure and Relations of the Genus Holopus. Abstract in Proc. Roy. Soc. Edin., vol. ix., 1875-78, pp. 405-410. TrautscHoLp, H., Ueber die Bezeichnung der Kelchplatten der Crinoideen. Budi. Soc. imp. des Nat. Moscou, t. lvii., 1882, No. 3 (1883), pp. 201-203. Wacusmuta, C., Notes on the Internal and External Structure of Paleozoic Crinoids. Amer. Journ. Sci. and Arts, vol. xiv., 1877, pp. 115-127, and pp. 181-191. Wacusmuty, C., and Sprincer, F., Transition Forms in Crinoids and Description of five new Species. Proc. Acad. Sci. Nat. Philad., 1878, pp. 224-266, 2 pls. Revision of the Palzeocrinoidea—Part I. The Families Ichthyocrinide and Cyathocrinide. Proc. Acad. Sci. Nat. Philad., 1879, pp. 226-378, pls. xv.—xvii. Revision of the Palocrinoidea—Part IJ. Family Spheroidocrinide, with the subfamilies Platy- crinide, Rhodocrinide, and Actinocrinide. Proc. Acad. Sci. Nat. Philad., 1881, pp. 177-41], pls. xvil.-xix. Weinpers, A., Die Morphologie der lebenden Crinoideen mit Beziehung auf die Form Antedon rosacea, Linck. Der Naturhistoriker, Sahrg. v., 1883, pp. 266-307. Winker, T. C., Description d’un Crinoide et d’un poisson du Systéme heersien. Archiv du Mus. Teyler. Harlem, vol. ii., 1869, pp. 297-307, pl. xxxviii. Wnicat, T., On the Occurrence of the Genus Cotylederma in the Middle Lias of Dorsetshire. Geol. Mag., N.S., Decade IL, vol. ii., 1875, pp. 505-506. Zitret, K. A., Handbuch der Palontologie. Paleozoologie, Bd. i. Abth. 1, 1876-80. Crinoidea in pp. 315-437, 96 cuts. Ueber Plicatocrinus Fraasi aus dem oberen weissen Jura yon Nusplingen in Wiirtemberg. Sitzungsh. d. II, Cl. k. baier. Akad. d. Wiss. Wien., 1882, pp. 105-113, Taf. i., i. The following short notices of recent Crinoids seem worth quoting in extenso. We have, unfortunately, no further knowledge of any of the types to which they relate. I. “Une espéce nouvelle d’Encrine vivante a été découverte par le révérend C. Pleydell a Newcastle sur la riviére Hunter, dans la Nouvelle Hollande; l’auteur propose de lui donner le nom d’Encrinus australis. Elle n’a pas de colonne vertebrale, mais le corps de l’animal a environ un cinquiéme de pouce de long, et est terminé dans cette direction par une base circulaire. A Vextrémité opposée du corps sont attachés cinq appendices claviculaires.” L? Institut, 1845, p. 292. Is this a Crinoid at all? ue “ Professor Sigmund Schultze aus Greifswald zeigte einen neuen Pentacrinus, welcher ihm von Amboina libersandt ist, in Abbildungen vor und sprach tiber die drei Arten, welcher er in dieser seltenen, bisher nur in 428 THE VOYAGE OF H.M.S. CHALLENGER. sieben Exemplaren bekannten Thiergattung unterscheidet ; der Pentacrinus Guettardi, der Pentacrinus eaput- Medusx und der Pentacrinus. Aradtii.” Bericht wu. d. Versainml. deutsch. Naturf. in Karlsruhe, 1858, p. 293. Two new species, Pentacrinus guettardi and Pentacrinus arndtii, are mentioned here, but nothing is said as to which came from Amboina, nor as to the nature of the other. The Amboina specimen was probably a Metacrinus, IIl. “T learn from a correspondent at -Melbourne, Mr. J. S. Poore, that during his visit to King George’s Sound, Western Australia, he there dredged up from 8 fathoms a living Encrinite. The stem, which was attached to a stone, was about 6 inches long ; the arms about 14 inch, of a beautiful rose-colour or pink, fading to white.” Sir. R. Owen in Ann. and Mag. Nat. Hist., ser. 3, vol. ix., 1862, p. 486. This may perhaps have been a Pentacrinoid larva, but if so, it was of most unusual size. Turther informa- tion about it from Australian naturalists would be most valuable. : INDEX TO AUTHORS QUOTED. Agassiz, A., 12, 18, 331, 333, 390, 393, 398, 401, 413. Agassiz, L., 64, 119, 197, 270-272. Allman, G. J., 161, 164, 185. Angelin, N. P., 41, 65, 66, 84, 172, 175, 176. Apostolidés, N. C., 101. d’Archiac, A., 245, 247, 323. Austin, T., 39, 183, 187, 272, 274— 388. Baily, W. H., 284. Baudélot, C., 117, 118. Barrois, C., 154. Bell, F. J., 303. Beyrich, E., 37, 126, 223, 245, 275, 294. Billings, E., 43, 75. Blainville, H. M. D. de, 187, 272, 300, 303. Bronn, H. G., 145, 188, 190, 191, 271, 294. Buckland, W., 22, 39, 81, 272, 277, 300. Buch, L. von, 190. Burmeister, H., 186, 187, 191. Carpenter, P. H., 2, 4, 18, 20, 25, 26, 35, 36, 39, 42, 46, 56, 57, 59, 60, 88, 94, 101, 102, 104-107, 143, 158, 165, 168, 169, 189, 259, 262, 268, 301, 306, 328, 393-395, 398, 47, 49, 51, 52, O13, 217, 227, 245, 250; 255, 269, 273, 282, 284, 288, 293, 331, 340, 343, 357, 370-372, 402, 403, 406, 408, 415, 416. Carpenter, W. B., 1, 2, 8, 36, 40, 48, 245, 292, 402, 408, 409, 412. Carpenter and Etheridge, 37, 49, 145, 147, 158. Chapman, E. J., 151, 195, 196. Charlesworth, E., 192. Claus, C., 403, 409. Cole, E., 18. Danielssen and Koren, 8, 29, 71, 225-227, 231-234, 242, 401. Desor, E., 272, 281. Dixon, F., 34, 284. Dujardin and Hupé, 191, 192, 197, 273, 301. 57, 130, 197, 204, 210, 306, 309, | Ellis, J., 278, 296, 301, 306, 50, 58, 59, 63, 67, 73, 87, 107, 108, 114, 116, 118, 132, 133, 72, a 294, 300. fear ¢ oy eke Etheridge, R., 276, 296. Etheridge, R., jun., 135. Eudes-Deslongschamps, E., 20, 131, 213. Filhol, H., 244, 269, 315-317, 319. Forbes, E., 35, 144, 187, 190, 192, 245, 281. | Gegenbaur, C., 409. Goette, A., 71, 157, 158, 167, 169, 41 Goldfuss, G. A., 35, 158, 187, 272, 27 | 403. | Graff, L. von, 134, 135, 324, 347, 364. | Greeff, R., 120, 406, 408. Grimm, 0. von, 404. | Guéttard, J. E., 272, 274, 294, 300. | Hagenow, F. von, 323. | Hall: eos QO bs Sees Hall and Whitfield, 298. Hamann, O., 112, 124, 410. Hertwig, O., 115. Hertwiy, R., 114. | Hoek, P. P. C., 351. Hoernes, R., 393, 394, 403. Huxley, T. H., 75, 188, 192. Jeffreys, J. G., 281, 313-315, 392. Jickeli, C. F., 408, 413-416. Koehler, R., 101, 105, 106, 11 Koninck, L. G. de, 153, 223. Lamarck, J., 272, 300. Lankester, E. Ray, 186, 189. Laube, G. C., 296, 414. Leuckart, R., 186, 188, 190, 191, 193. Linnaeus, C., 272, 300, 302. Loriol, P. de, 9, 15, 17, 22, 25, 26, 35, 47, 126, 131, 135, 142, 146-148, 153, 183, 186, 188, 189, 2 212-216, 223, 225, 2 248, 257, 270, 272-274, 276, 2 286, 299, 403. 67, 85, 368, 393-400, 402, 414. 269, 272-274, | als 4, 284, 2 193, 217. 2, 406, 407. 201, 202, 256, 257 297, 430 Ludwig, H., 67, 86, 88, 89, 92-96, 101, 102, 104-106, 108, 111-113, 116-120, 124-127, 209, 210, 229, 230, 248, 250-254, 261, 268, 395, 398, 400, 404-406, 408, 409, 411, 412, 416. Liitken, C. F., 4, 85, 145, 146, 168, 248, 273, 277, 283, 301-306, 308, 309, 311, 330, 333, 394. Manzoni, A., 245. Marshall, A. M., 255, 408-412. Meek, F. B., 45, 53, 148, 184. Meek and Hayden, 297, 298. Meek and Worthen, 41, 61, 75, 87, 162, 163, 177, 217. Meneghini, G., 238, 245-248, 258. Meyer, A. B., 130. Meyer, H. von, 34, 271, 272, 294. Michelin, H., 216. Miller, J. S., 73, 145, 151, 183, 189, 191, 27 277, 278, 300, 302, 304, 306, 308, 397. Miller, S. A., 20, 42-44, 183, 185, 192. Milne-Edwards, A., 237, 269. Moseley, H. N., 128, 129, 210, 320, 346, 348, 352, 354, 356, 359, 362, 365. Miller, J., 2, 5, 8, 9, 49, 66, 73-77, 85, 86, 117, 145, 147 0) Wil 79s 90s On Sb: 1965.2 2-275, cs (2, 274, 300, 302, 304, 306, 308, 394, 397, 404, | 405, 415. Miiller, P. L. 8., 300, 302. Nicholson and Etheridge, 192. Oersted, A. S., 301, 306, 307. W@Orbigny, A., 9, 25, 54, 142, 183, 192, 197, 199, 245-249, 270, 272, 274, 370. Parra, A., 301. Perrier, E., 28-30, 47, 94, 101, 102, 104, 106-108, 117-119, 122, 127, 195, 244, 245, 262-266, 268, 269, 316, 398-402, 404-408, 416. Perrier and Poirier, 406. Phillips, J., 276. Picard, K., 270, 294. Pictet, FE. Ji, 191, 192, 197, 273, 274. Pourtalés, L. F. de, 65, 160, 197, 204, 250, 258, 259, 261-263, 265, 330, 331. Quenstedt, A., 4, 7, 15, 16, 20, 22, 24, 25, 34, 39, 54, 55, 142, 183, 187, 191, 211, 257, 273, 276- 278, 281, 284, 286, 294, 296, 299, 308, 323. 245, 246, 248- 268, 306, 309, THE VOYAGE OF H.M.S. CHALLENGER. Ramsay, A., 276. Roemer, F., 48, 213. Romanes and Ewart, 112, 115. Salter, J. W., 192, 193. Sars, M., 25, 28, 29, 72-74, 90, 107, 130, 245, 246, 248-254, 259, 261-265, 266, 268. | Schlotheim, E. F. von, 272, 273, 294, 300, 407. Schliiter, C., 35, 144, 147, 148, 151, 212, 213, 371, 402, 403. Schultze, L., 41, 47, 48, 152, 158, 160. | Selenka, E., 412. Semper, C., 108, 110, 130, 133, 236. Sigsbee, C. D., 332. Simroth, H., 2, 116. Sladen, W. P., 106, 168, 195, 303, 340, 358, 394- 396, 398-401. Steenstrtp, J. J. S., 211. Strombeck, A. von, 294. Stiider, T., 398. Suhm, R. von W., 133, 134, 369. Teuscher, R., 118, 120, 404, 406. Théel, H., 122. Thomson, C. Wyville, 1, 4-6, 8, 12, 18, 19, 21, 23, 32, 3%, 39, 48, 52, 54; 60, 67, 72; 77, 8d; OL; | 94, 95, 107, 110, 127, 128, 188, 192, 193, 197— | 199, 201, 202, 204, 206, 210, 217-219, 221, 229, 224-226, 230-235, 238-245, 249, 259, 261-263, 273, 278-281, 285, 289, 301-306, 308, 309) 312, 313, Sllb=oLlGpolo 22.030: 331, 333-335, 337, 340, 351, 355, 360, 390, 402, Trautschold, H., 152. Verrill, A. E., 130. Wachsmuth, C., 63, 65, 76, 146, 147, 156-182. Wachsmuth and Springer, 24, 32, 39, 41, 42, 46-48, 54, 61, 62, 64-66, 75, 76, 86, 87, 149, 150, 152-157, 159-163, 165-171, 173-175, 177, 178, 180-184, 195, 217, 258, 371, 372. Weinberg, A., 407-409, 415. | Welldon, W. F. R., 407. Zittel, K., 25, 26, 47, 48,51, 66, 142, 145, 147, 152, 157, 158, 160-163, 165, 170, 185-189, 191, 197, 213, 214, 223, 245, 248, 258, 270, 273, 274, 276, 402, 403. 160, 186, 187, 190, 197, 211, GENERAL INDEX. The figures in dark type indicate the page on Abactinal side, 157, 158, 171. Abactinal system, 156, 169, 172. Actinal side, 156, 158, 171, 179. Actinal system, 156, 169, 172, 178. Actinocrinide, 61, 62, 86, 149, 158, 164-181. Actinocrinus, 62-66, 156-158, 164-166, 169, 172, | 177-180, 182, rugosus, 79. verneuilianus, 165. Actinoidea, 186, 187, 190. Actinometra, 33, 36, 59, 68, 74, 78, 85, .93, 95, 97, 102, 104, 111, 115, 121-123, 127, 143, 153, 154, 284, 291, 337, 377, 381-385, 411; arms of, 55-57, 60, 69, 70; digestive tube of, 91, 92; disk of, 69, 70, 85; geographical and bathymetrical distribution of, 136— 141; mouth of, 69, 403; plexiform gland of, 103, 104. bennetti, 55, 127, 337. dissimilis, 110, 111. fimbriata, 52. jukesi, 67, 69, 85, 91, 130, 132, 319, 337 (FL lv. fig. 1). loveni, 132. magnifica, 57, 69, ile fig. 7). meridionalis, 280, 337. multiradiata, 49, 52, 337. nigra, 96, 4-10)""120-122, 124, (Pl. lxi. fig. 6). nobilis, 55, 57, 69, 110, 111. novee-guinee, 49. parvicirra, 50, 52, 57, 67, 102, 103, 107, 120, 121, 124, 138, 283, 337, (Pl. Ixi. figs 2-5). 183, 185, 192, 394. 133, ales (QE What 416 which the genus or species is first described. Actinometra pulchella, 91, 103, 104, 109, 137, 337 (Pl. lx. fig. 1; PL Ixi. fig. 1). robusta, 144. schlegeli, 55. solaris, 10, 49, 51, 52, 58, 91, 280. stellata, 132, 319. stelligera, 69, 70, 337 (Pl. lvi. fig. 8). strota, 60, 67, 69, 85, 86, 129, 130, 133 (PL. liv. figs. 10, 11; Pl. lv. fig. 2). trachygaster, 127. typica, 4, 10, 49, 51, 52, 337. Actinozoa, 193. Agassizocrinus, 132, 153, 213, 217, 319. Agelacrinide, 194. Agelacrinoidea, 192. Agelacrinus, 85, 192. Allagecrinus, 146, 147, 152, 158, 159, 169, 213. austini, 37. Ambulacra, 56, 57, 68-70, 78-85, 93, 127, 179-181 ; of (Comntnles 83-85; of Metacrinus, 81, 82; of Pentacrinus, 78-80; subtegminal ambulacra of Paleocrinoids, 164, 179. Ambulacral epithelium, 59, 93, 112, 113, 415. Ambulacral groove ; see Ambulacra and Food-groove. Ambulacral nerve, 59, 70, 93, 96, 111-115, 118, 120, 408-416 ; of Antedon eschrichti, 112, 118, 411 ; of the Blastoidea, 413. Ambulacral plates, 55, 63, 65, 74-85, 165, 174-181, 184. Ampliura, 395, 396. Anal appendage, 41-46, 371, 372 Anal plate, 38, 73. Anal series, 45, 372. Anal tube, 69, 70, 81, 89. Anambulacral plates, 57, 62, 76-78, 80-86,$165, 180, 184. 2 =“ 45 Anchylosis, 3, 37. Ancyrocrinus, 19. Antedon, 33, 36, 57, 68, 74, 94, 127, 129, 143, 144, 154, 237, 249, 268, 291, 376-385, 402- | 404; ambulacra of, 83-85 ; digestive tube | of, 88, 89; disk of, 68, 84, 85; geographi- cal and bathymetrical distribution of, 136— 141; labial plexus of, 97-100, 404-407 ; plexiform gland of, 101, 102, 235. acoela, 57, 83, 84, 93, 109, 110, 113, 128 ~(PL liv. figs. 1-4; Pl. lv. fig. 5). angusticalyx, 57, 83, 84, 93, 109, 110, 113, 128, 135 (PI. liv. fig. 5 ; PL ly. fig. 6). antarctica, 92, 98. basicurva, 84 (Pl. liv. fig. 9; Pl. lv. fig. 7). campichei, 144. carinata, 98, 109, 124, 130, 137, 235 (Pl. Ix. | fig. 2). dentata, 36, 130, 137. eschrichti, 10, 52, 55, 62, 67, 78, 83, 88, 90, 92, 93, 95-102, 109, 111, 112, 114, 118, 120, 122-124, 133, 137, 144, 153, 208— 210, 319; ambulacral nerve of, 112, 118, 411; parambulacral network of, 123, 124, 416; radial blood-vessels of, 96; spongy organ of, 98, 99 (PI. lix. figs. 6, 7; Pl. Ix. figs. 3-6), Sluctuans, 280, hageni, 36. inaequalis, 83 (Pl. liv. fig. 8). incerta, 57, 83 (PL. liv. figs. 6, 7). lusitanica, 315. milleri, 73. multiradiata, 84, 85 (Pl. lv. figs. 3, 4). phalanyium, 10, 36, 130, 318. protecta, 58. quadrata, 98, 99. rhodanicus, 144. rosacea, 49, 50, 52, 58, 67, 70, 86, 88, 93, 95-98, 100-102, 104, 107-112, 118, 120, 122, 124, 125, 127, 129, 130, 133, 134, 280, 304, 404, 411, 413; anal plate of, 73; calyx interradials of, 39; genital glands of, 109; labial plexus of, 98; plexiform gland of, 102, 104; spongy organ of, 100 (PI. lvi. fig. 6; Pl. lix. fig. 5). serobiculata, 336. spinifera, 277. Antedonin, 129. Anthodiata, 186, 190, 191. THE VOYAGE OF H.M.S. CHALLENGER. | Apical dome plates, 157, 167, 168; of Actinocrinide, | 164, 167; of the Blastoidea, 164, 173; of Cyathocrinide, 164,172; of Glyptocrinus, 184 ; of Ichthyocrinide, 181, 183; of Periechocrinus, 171, 172; of Platyerinide, 164, 175-178; of Rhodocrinidz, 164 ; of Strotocrinus, 171, 172. Apical system, 2, 157, 172, 393-402. Apiocrinide, 32, 48, 54, 142, 183 | 286, Apiocrinites, 245, Aptocrinus, 8, 11, 25, 42, 49, 53, 68, 76, 125, 126, 135, 145-147, 150, 153, 154, 181, 183, 211, 223, 230, 249, 256, 270, 276, 289, 293, 340. constrictus, 24, 257. cornutus, 258. crassus, 256. , 222, 225, 247, insiynis, 9. magnificus, 256. martini, 39. milleri, 215. murchisonianus, 256. parkinsoni, 9, 131, 150. rotssyanus, 39, 149, 150, 183, 215. Arm-groove, 64, 65, 77-83. Arms, 47-56, 154, 194; of Actinometra, 55-57, 60, 69, 70; of Bathycrinus, 232, 233, 236; of Crinoids and Cystids compared, 189 ; of Eztracrinus, 59— 61, 224 278 ; of Holopus, 207-209 ; of HHyocrinus, 52, 53, 219, 224; of Pentacrinide, 55, 56, 154, 155, 277, 278, 284-287 ; of Rhizo- crinus, 52-54, 64, 65, 267. Article basal of Apiocrinus and Bourgueticrinus, 3, 25, 153, 257. Articulata, 145, 182, 195, 196. Articulation, bifascial, 8, 53, 231, 280, 304, 326, 329, 330; muscular, 9-11, 146, 194; trifascial, 8, 9, 53, 231-233. Asterencrinidea, 187. Asterias, 245, 395, 396, 399, 400. Astrocrinide, 194. Astrocrinus, 132. Atelecrinus, 34, 36, 56, 58, 68, 127, 137, 138, 140, 141, 144, 291, 292, 294, 371. balanoides, 376, 380. cubensis, 379. Sills ‘ Axial cords of rays and arms, 31, 114-127, 146, 407— 416; of Bathycrinus, 31, 119, 236; of Holo- pus, 119, 209, 236; of Pentacrinus, 124, 126, 293, 294; of Rh*zocrinus, 119, 126, 252, 253. REPORT ON THE CRINOIDEA. Axillary, 9, 10, 33, 48, 58-61, 90, 125; of Hudesi- crinus, 215; of Holopus, 204-206. Avicula, 134, 369. Balanocrinus, 143, 270-272, Barycrinus, 54, 61, 363. herculeus, 61, 224. Basals, 2, 3, 33-39, 71, 73, 106, 124-126, 157, 158, 168-172, dpe 393-399, 402, 403; of Bathy- 26-228; of Comatule, 34-36, 251, 284, 402, 403; of Pentacrinus, 34, 35, 282-284, 293, 336; of Rhizocrinus, 36, 248-253 ; of Thaumatocrinus, 34, 36, 371. Basaltiformes, 296. Bathycrinus, 38, 48, 54, 56, 58, 62, 91, 104, 117, 12 143, 213, 214, 222, 223, 225, a 938, 243, 248, 252, 254-256, 289-292, 386, 388, 391, 392; arms “afi 232, 233, 236; axial cords of, 31, 236; basals of, 37, 226-228; chambered organ of, 34, 107, 235; covering plates of, 74, 234; digestive tube of, 33, 89, 90, 287. crinus, 37, 2 236; disk of, 234, 235; genital glands of, 109; geographical and bathymetrical range of, 136-140, 391, 392; nerves in | stem of, 31, 119; pinnules of, 233, 234; plexiform gland of, 89, 90, 101, 235; primary interradial cords of, 126, 228-230; radials of, 3, 37, 230, 231; stem of, 23, 24, 26-28, 226; trifascial articulations of, stem of, 23, 24, 26-28, 226; axis in stem of, 107, 235; visceral mass of, 33, 90, 234; water-tubes of, 93, 236. aldrichianus, 8, 10, 31, 37, 71, 119, 120, 130, 134, 225-235, 237-240, 241, 242, 243, 244, 376, 386, 389, 391 (Pl. vii.; PL viia. figs. 1-21; PI. viib. ; Pl. viiia. figs. 4, 5). campbellianus, 227, 23 238, 239, 240, 24 391 (Pl. viia. figs, 22, carpentert, 8, 71, 226, 237, 244, 386, 389, 391. gracilis, 71, 227, 231, 232, 235, 237, 238, 248, 244, 245, 374, 386, 389-391 (PI. viiia. figs. 1-3). Bathymetrical range of Crinoids, ae 138. Belemnocrinus, 38, 151, 217, 258, 259. , florifer, 259, 270, 363. pourtalesi, 259. (ZOOL, CHALL, EXP. —PART xxxu1.—1884,) vascular 233, 235, 237, 376, 386, 389, 23; PL. viii). 227, 231-234, 2, ps 5) 27, 119, | PCallicrinus, 8, 9, 53, 231-233; | 433 Blastactinota, 190. | Blastoidea, 54, 68, 75, 109, 132, 148, 149, 154, 164, 173, 175, 186, 188-195, 413, 414. 3lood-vascular ring, 1, 96, 105, 106, 407. Blood-vascular system, 96-109, 405-407. Blood-vessel, intervisceral, 87, 97-105, 405, 406; radial, 1, 59, 70, 92, 93, 96, 97, 100. Botryocrinus, 61. Bourgueticrinide, 142, 225, 269, 290, 386; calyx of, 33; stem of, 6, 7, 23-31, 131. Bourgqueticrinus, 24, 142, 148, 154, 222, 225, 237, 245-249, 254-258, 270, 276, 323, 392. equalis, 256. alabamensis, 143, 257. didymus, 258. ellipticus, 24, 256. hotessieri, 246, 259, londinensis, 257, 269. ooliticus, 257. 248, 257. 247, 258. SUuesst, thorenti, Brachiata, 186, 187, 191. Briariden, 276, 278, 296. Brisinga, 398-400. Cainocrinus, 35, 272, 273, 281-283. 157, 400. Calyx, 33-46, 124-126, 393, 394; of Butiycrinus, 37, 226-231; of Cotylecrinus, 213, 214; of Cyathi- dium, 211, 212; of Eudesicrinus, 215; of Extracrinus, 274-276; of Holopus, 33, 36, 199-204, 213; of Hyocrinus, 33, 36, 218, 223; of Pentacrinide, 33, 291-294; of Rhizocrinus, 3, 29, 33, 34, 36, 38, 248-253, 257. | Canaliculata, 196. Carpocrinus ornatus, vault of, 180, 181. | Caulaster, 195, 399, 401, 402. 273, 278-281, 334. caput-Meduse, 301. Central capsule, 410-414, 416. Centro-dorsal of Le eae 25; of Comatule, 25, 106, 107, 132, 292; of Cotylecrinus, 213-219. Ceriocrinus, 46. Chambered organ, 15, 23, 33, 104-108, 114, 119, 194, 404-406; of Bathycrinus, 34, 107, 235; of Comatule, 106, 107, 292, 404, 412; of Penta- crinus, 105, 292, 412. Chelocrinus, 295. acutangulus, 294. Chladocrinus, 271, 272: Cenocrinus, ‘ li 55 434 Circular commissure, 40, 117, 413; of Bathycrinus, 126, 228-230; of Comatule, 125; of Penta- crinus, 125; of Rhizocrinus, 126, 258. Cireumvisceral coelom, 67. Cirri, 7, 107, 108, 114, 132, 414; of Bourgueticrinide, 27, 28; of Comatule, 132, 414; of Pentacri- | nid, 12, 288, 342. Cirrus-vessel, 15, 23, 107, 292, 412. Clypeaster, 394. Coccocrinus, vault of, 160-163, 170, 174, 175, 178, 185. Comaster, 151, 403. Comatula, 3, 4, 6, 8-10, 18, 19, 22, 24, 25, 33-36, 38, 40, 44, 45, 48-53, 55, 56, 58, 59, 62, 63, 68, 70-74, 76, 78, 83-85, 88, 90, 91, J3-9o oie LOG Oe LOD LT wo: 124, 125, 130-135, 144-148, 154-156, 164-166, 169, 175, 3177, 181, 183-185, 192, 230, 249, 252, 254, 255, 261, 273, 277, 279, 285-287, 289-294, 316, 319, 324, 326, 337, 340, 401, 412, 413, 415. Ambulacra of, 68, 156; ambulacral plates | of, 62, 74, 83, 84, 175, 181; arms of, 52, 55, 147, 337; axial cords of, 119, 121~ 123, 408, 409; basals of, 34-36, 251, 284, 402, 403 ; centro-dorsal of, 25, 106, 107, 132, 292; chambered organ of, 106, 107, 292, 404, 412; circular commissure of, 125; cirri of, 132, 414; disk of, 68- 70, 84, 85, 90; geographical and bathy- metrical distribution of, 136-141; mon- strosities of, 70; oral plates of, 71, 72, 156; pinnules of, 58, 59, 83; radials of, 147, 289, 293, 294; reparation of, 60, 255; syzygies of, 4, 53. Comatulide, 142, 192, 370. Conocrinus, 245, 247, 248. cornutus, 258. pyriformis, 248, 257. seguenzal, 257. suesst, 257. Consolidating plates of Cupressocrinus, 162. Convoluted organ of Actinocrinide, 87, 165. Costal plates, 396-399. Costata, 190, 195. Cotylecrinus, 68, 143, 161; systematic position, 213- 217. docens, 213." miliaris, 214. Cotylederma, 213. 363, 370-372, 393, | THE VOYAGE OF H.M.S. CHALLENGER. Covering plates, 62-66, 74-83, 115, 166, 173-175, 181, 185, 220. Crinactinota, 190, 191. Crinoidea, 186, 187, 188-195. Crotalocrinus, 54, 65, 66, 157. | pulcher, 65, | Culicocrinus, summit plates of, 170, 175. | Cupressocrinus, 48, 150, 152, 153, 162. Cupule of Cotylecrinus, 213, 214. | Cyathidium, 143, 202; systematic position, 211-216. sptleccense, 212. Cyathidiocrinide, 211. Cyathocrinide, 153, 155, 160, 162, 164, 173, 181. Cyathocrinus, 44, 45, 48, 60-66, 146, 151, 154, 161— 164, 169, 173-175, 178, 185, 224, 394-398. alutaceus, summit of, 173. zowensis, ambulacra of, 65. levis, summit of, 173. longimanus, ambulacra of, 65, 66, 84. malvaceus, summit of, 172. ramosus, ambulacra of, 66. Cycloblastus, 191. Cyclocystoides, 192. Cystide, 192. Cystidea, 54, 109, 132, 148, 149, 154, 186, 188-195. Cystoblastus, 191, Cystoidea, 186, 195. Deltoid pieces of the Blastoidea, 162. | Democrinus, 28-30, 245, 264, 268, 269. parfaiti, 262, 264, 269. Dendrocrinus caset, 45. navigiolum, 20. Dichocrinus, 39, 222, 223. intermedius, 223, Digestive tube, 1, 84, 86-92. Disk, 1, 67, 75, 80, 81, 84, 85, 88, 90, 182, 184, 342 ; | of Actinometra, 69,70, 85 ; of Antedon, 68, 84, 85; of Bathycrinus, 234, 235; of Hyocrinus, 219; of Metacrinus, 59, 68, 80, 81, 93, 342; of Pentacrinus, 68, 76, 77, 91, 279. Distichals, 49, 50, 177. Dorsocentral, 18, 132, 157, 158, 168, 169, 274, 275, | 393-396, 398-400. | Echinospheerites, 192, 195. | Echinozoa, 95, 105, 106, 193, 194, 406. | Edrioaster, 192. ‘ Edriocrinus, 148, 194, 195, 217, 319. | Eleacrinus, 164, 173. | Eleutherocrinus, 132. REPORT ON THE CRINOIDEA. 435 Emedullata, 151, 196. Encrinide, 142, 187. Encrinites dubius, 294. Encrinus, 25, 34, 35, 48, 49, 51, 117, 125, 126, 142, 143, 145, 149, 150, 152-155, 230, 272, 275, 284, 294-296, 300, 340, 363, 394, 395. beyrichi, 270, 295. caput-Medusee, 274, 300. gracilis, 37, 153. ‘ liliiformis, 294. pentactinus, 299. Epizygal, 4, 50, 219. Erisocrinus, 150, 152-154. Eucalyptocrinus, 151, 157, 160, 195, 400. crassus, root of, 20. Eucrinoidea, 186-189. Eudesicrinus, 10, 143, 149, 161, 202, 205 ; systematic | position of, 2138-216. Eudiocrinus, 36, 47, 58, 68, 137, 138, 140, 143, 291, 373. atlanticus, 47, 127. indivisus, 47, 48, 58, 127, 137. japonicus, 47, 109, 127, 339, 378. sempert, 36, 47, 127. varians, 47, 58, 127. Engeniacrinide, 142, 216. Eugeniacrinites, 245. Eugeniacrinus, 68, 131, 142, 161, 211, 214, 927, 247, 248. mayalis, 215. pyriformis, 247. Eupachycrinus, 46, 153, 154. Extracrinus, 8, 30, 34, 41, 43, 51, 59-61, 76, 131, 143, 145, 149, 150, 154, 181-183, Tle 272s 274-278, 281, 288, 296-299, 308, 371, | 394, 395; arms of, 59-61, 224, 277, 278; calyx of, 274-276 ; ceological range of, 296-298 ; stem of, 276, 277, 287. briareus, 20, 22, 54, 55, 81, 131, 274, 975, 278, 296, 297, 313. subangularis, 16, 22, 30, 54, 274, 277, 413. Food of Crinoids, 132, 133. Food-grooves, 56, 64, 68, 69, 77-85, 92, 156, 163- 166, 173, 180, 236, 415. Free rays of Ichthyocrinide, 181; of Platyerinus, 177. Genital canal, 96, 209. Genital cord, 61, 63, 108, 110, 111, 209, 210. 6, 6, Genital glands, 56, 57, 61, 63, 83, 108-111, 220. Genital plates of Echini, 2, 168, 169, 172, 393-398, 402. Genital vessels, 97-100, 105, 108, 109. Geographical range of Crinoids, 136, 137. Gissocrinus, 66, 174. punetuosus, ambulacra of, 65. Glyptocrinus, 183-185. decadactylus, 183. schaffert, 20. Glyptocystites, 20. Goniaster, 245. Growing point of arms, 56, 59, 60, 400. Guettardicrinus, 39, 146, 149-152, 181, 289. Gymnocrinus, 143, 216. Habits of Crinoids, 130-132. Habrocrinus, 66, 180. Haplocrinus, 54, 157-159, 163, 164, 167, 170, 171. mespiliformis, 158. Heterocrinus, 42, 45, 53, 154, 267, 363. constrictus, 53, 224. simplex, 53, 224. Hexacrinus, 39, 176, 217. Holopide, 197, 216, 386. Holopocrinide, 211. Holopodide, 142, 143, 195, 217. Holopus, 38, 48, 127, 131, 141, 143, 145, 149, 155, 159-161, 172, 185, 19'7, 198-217, 386, 388. Arm-joints of, 207, 209 ; axial cords of, 119, 209, 236; bivium and trivium of, 202, 207; calyx of, 33, 36, 199-204, 213; colouring matter of, 129, 204, 210 ; genital glands of, 63, 110, 210; geographical and bathymetrical distribution of, 136-138, 140, 141; oral plates of, 70, 72, 95, 156, 198, 208; pinnules of, 207, 208 ; second and axillary radials of, 204-206 ; system- atic position of, 211-217; tentacles of, 208. rangi, 199-208, 380, 381, 384, 389, 386, 388, 389 (Pls. i—vb.; Pl. ve. figs. 1-3). Hybocystites, 191. Hydrospires of Blastoidea and Cystidea, 194. Hyocrinide, 31, 217, 223, 386. Hyocrinus, 48, 54, 60-62, 73, 83, 134, 142, 146, 149, 155, 160, 161, 176, 179, 181, 185, 208, 217, 218, 219, 221, 222, 234, 236, 242, 267, 289, 371, 386, 388, 391, 392; arms of, 52, 53, 219, 224; calyx of, 33, 36, 218, 223; covering plates of, 74, 220; genital glands of, 109, 220; geographical and bathymetrical distribution of, 137-140 ; 436 THE VOYAGE OF H.M.S. CHALLENGER. Hyocrinus continned— oral plates of, 70, 72, 94, 95, 156, 219; pinnules of, 59-61, 219, 224; side plates of, 82, 220; stem of, 5, 31, 32, 218, 221; systematic position of, 222-224; testes of, 220; water-pores of, 94, 95, 219, 220, bethellianus, 218-222, 240, 376, 378, 386, | 389, 391 (Pl. ve. figs. 4-18; Pl. vi.). Hyponome sarsi, 67, 85, 166. Hypozygal, 4, 50, 54. Ichthyocrinide, 42, 76, 149, 155, 166, 181-185, 195. Ichthyocrinus, 185, 195. Ilyaster, 401. Ilycrinus, 225. Inarticulata, 145. Metacrinus, 10, 138, 110, 124 Infra-nodal joint, 13. . Interarticular pores, 18. Internal casts of Actinocrinidew, 165, 174, 179, 182 ; of Platycrinus, 179. | Interpalmar areas of disk, 69, 81, 84, 165, 166, 174, 180. | Tnterradials of calyx, 38-46, 74, 162, 178, 371. Interradials of perisome, 42-44, 73, 74, 76, 183, 371. Intervisceral blood-vessels, 87, 97-105, 405, 406. Tntervisceral coelom, 67, 109. Intervisceral plexus, 86, 87. | Intra-radial commissure of Comatula and Pentacrinus, 125, 126; of Bathycrinus, 127, 229 ; of Rhizo- | crinus, 126, 253. Tocrinus, 46, 363. Isis, 272, 300, 302. Tsocrinus, 271-273, 281. pendulus, 34, 284. Labial plexus, 93, 97-101, 103-105, 404-406. Lecanocrinus reemeri, 217. Lepidodiscus, 85. Lichenocrinoidea, 192. Lichenocrinus, 192. ; dubius, 20. Ligaments, of arms, 7-9, 414 ; basiradial ligaments of Bathyerinus, 228 ; of stem, 5-7, 13, 23. Madreporie canal of Echinozoa, 106, 194, 406. Mariacrinus, 155, 171. Marsupiocrinus, vault of, 171, 175-177 depressus, 176. radiatus, 176. Marsupites, 34, 48, 68, 132, 142, 145, 151, 155, 181, 183, 196, 216, 394-398. Marsupitide, 142. Megistocrinus, 54. Mesocrinus, 24, 237, 255-257, 323. , 128, 134, 148, 152, 154, 205, 270-272, 275, 283, 285-288, 291, 300, 304, 311, 320, 334, 336, 339, 840, 341-344, 357, 359, 360, 362, 369, 370, 387, 388-391; arms of, 55, 285, 286, 342; cirri of, 288, 342; disk of, 59, 68, 80, 81, 93, 342; geographical and bathymetrical distribution of, 136- 142, 343; pinnules of, 10, 55, 58, 155,- 341, 342; pinnule-ambulacra of, 81, 82; radials of, 48-51, 341, 357; stem of, 14, 15, 17, 19, 287, 288, 342, 343. angulatus, 19, 51, 60, 70, 80, 81, 110, 134, 287, 288, 293, 342, 344, 345, 346, 348, 355, 357, 364, 366, 369, 370, 377, 387, 389 (Pl. xii. figs. 1-14; Pls. xxxviii., xxxix.). cingulatus, 17, 80, 81,.287, 288, 342, 344, 346, 347, 348, 355, 357, 358, 369, 377, 387, 389 (Pl. xl.; Pl xii. figs, 14), costatus, 17, 35, 82, 129, 284, 288, 342, 344, 359, 360-362, 363-366, 368— 370, 378, 387, 389 (PL xlvii. fig. 13 ; Pl. xlix.). Metacrinus dredged by the “ Vega,” 340, 343, 344, 368, 387, 388. interruptus, 134, 288, 342-344, 867, 868, 369, 377, 387, 388 (Pl. lii.). moseleyi, 17, 129, 341, 344, 855, 356, 357-359, 378, 387, 389 (Pls. xlv., xlvi.). ; murrayt, 17, 78, 81, 82, 128, 140, 184, 326, 342-344, 349, 350, 351, 352, 355, 377, 378, 387, 389 (Pl. xli. figs. 12-17; Pl. xlii.). nobilis, 17, 80-82, 287, 344, 350, 851, 352, 353, 355, 369, 377, 387, 389 (Pl. xli. figs. 5-11; Pl. xiiii.). nodosus, 51, 76, 80-82, 289-291, 342, 344, 359, 362, 364, 365, 366, 368— 370, 377, 387, 389, 391 (Pis. 1, li). rotundus, 343, 344, 357, 387, 388. stewarti, 288, 344, 387. superbus, 344, 351, 352, 355, 387. tuberosus, 134, 288, 342, 344, 869, 870, 377, 387, 389 (Pl. liii. figs. 1-6). varians, 17, 129, 134, 288, 342, 344, 351, 352, 358, 354, 355, 366, 378, 387, 389 (Pl. xliv.; Pl. xlvii, figs. 6-12). REPORT ON THE CRINOIDEA. Metacrinus wyvillit, 129, 136, 288, 342-344, 354, 357, 358, 359, 360, 362-365, 368, 377, 378, 387, 389, 391 (Pl. xlvii.| figs. 1-5 ; Pl. xlviii.). Miecropocrinus, 143, 216. _ Millericrinus, 8, 11, 25, 49, 54, 131, 135, 153, 256, 270, 271, 281, 282, 340. nodotianus, 256. pratti, 20, 26, 51, 132, 328. simplex, 256. Monstrosities, 70, 347. Mouth, 56, 68-70, 91, 103, 156, 166, 403. Mouth-shields of Ophiurids, 2, 169. Museles, 9-11, 113-115, 414, 415. Myelodactyloidea, 192, 193. Myelodactylus, 192, 193. Myrtillocrinus, 146, Myzostoma, 70, 133-135, 324, 358, 364, 369. deformator, 324. pentacrini, 324, 364. wyville-thomsoni, 347, 362, 364. Neocrinoidea, 9, 38, 49, 51, 59, 142, 145, 147-157, 160-162, 170-173, 181, 185, 194, 195, 196, 217, 224, 270, 295, 309, 411. Neocrinus, 273, 279, 280, 302, 334. Nerve-fibres of stem, 23, 31, 116, 119, 120. Nervous system, 111-127, 407-416. Neuro-vascular axis of stem, 194, 413. Nodal joints in stem of Pentacrinide, 4, 12-15, 17, 19,105, 107, 291. Ocular plates of Echini, 2, 168, 169, 393, 394, 402. Odontophore of Starfishes, 2, 398-400. Ollacrinus, 157. Onychocrinus, 41, 42, 151, 181, 182, 372. Oral pinnules of Antedon, 59, 115. Oral plates, 2, 70, 73, 94, 95, 156-164, 167-173, 178, 184, 185, 398 ; of Bathycrinus, 234; of Coma- tula, 71, 72, 156; of LZolopus, 70, 72, 95, 156, 198, 208; of Hyocrinus, 70, 72, 94, 95, 156, 219; of Rhizocrinus, 70, 72, 156, 219, 255 ; of Thaumatocrinus, 70, 72, 160, 161, 371. Orocentral, 158, 159, 167-172, 178, 184. Ovary, 109-111, 210. Ovoid gland, 104-106, 406, 407. Palxocrinoidea, 32, 38, 39, 47-49, 54, 61, 68, 72, 132, 135, 147-158, 164—167,.172, 173, 181, 185, 194, 195, 217, 218, 224, 270, 271, 295, 358, 363, 370-372, 394. ' Paleostoma mirabilis, 2. Parambulacral network, 123, 124, 415, 416. 437 Parasites of Crinoids, 133-135. Palma animal, 301. Palmars, 49, 177. Palmier marin, 300. Pelmatozoa, 186, 18'7, 188, 190, 191, 193-195, 413. Pentacrinide, 56, 71, 83, 110, 119, 125, 132, 142, 143, 146, 150, 154, 156, 166, 183- 185, 192, 228, 2°70, 271, 277, 289- 201, 294, 295, 310; Bh7, 320; 322; 323, 326, 337, 386. Ambulacral skeleton of, 62, arms of, 55, 56, 154, 155, 284-287 ; calyx of, 33, characters of young, 289— cirri of, 12, 288, 342; colouring matter of, 128, 129, 210; colonies of, 130, 1381; disk interradials of, 73, 76, 183; ovaries of, 110; parasites of, 134, 185 ; pinnules of, 55, 58, 59, 155, 286; stem of, 3-6, 12-23, 287, 288, 290, 291, 315-319, 342, 343; syzygies of, 4, 5, 254, 326. Pentacrinin, 128, 129 ; 204, 210. Pentacrinites, 272, 273. vulgaris, 274, 300. Pentacrinoid larva of Comatula, 24, 39,70, 89, 95, 95, 101, 107, 108, 116, 127, 158, 159, 161, 164, 194, 214, 219, 237, 251, 290, 396. Pentacrinus, 3, 7-10, 13, 17-19, 49, 50, 53, 58, 62, 66, 74, 76-81, 84-88, 90, 97, 101, 103, 104, 110, 117, 126,127, 128-132, 134— 141, 143, 145, 148, 155, 165-167, 173, 181, 182, 192, 195, 210, 211, 228-231, 235, 244, 252, 256, 259, 261, 271, 272, 278, 274-300, 302-304, 316-320, 326, 340-343, 364, 369, 386, 388, 391, 392, 394, 409, 415. Basals of, 34, 35, 282-284, 293, 336; chambered organ of, 105, 292; disk of, 68, 76, 77, 91, 279; geographical and bathymetrical distribution of, 136-141, 300, 343, 391, 392; geological history of, 294-300 ; intervisceral blood-vessels of, 101, 102; labial plexus of, 93, 100 ; plexiform gland of, 105; primary inter- radial cords of, 124-126, 292, 293; radials of, 289, 293, 294; radial plug of, 34, 293; stem of, 12-23, 287, 288, 315-319, 342, 343; vascular axis in stem of, 23, 107 ; water-vascular ring of, 93. 438 Pentacrinus alternicirrus, 12, 19, 21, 44, 55, 77, THE VOYAGE OF H.M.S. CHALLENGER. 78, 80, 128, 135, 136, 177, 184, 277, 282, 284-286, 288, 293, 299, 305, 310, 313, 315, 318, 320, 321, 322, 323, 324, 326, 335, 337, 346, 353, 364, 377, 378, 386, 359, 391, 412 (Bish Pacxy., -xxviel;) PI Scxyir, © figs: 1-10), asteriscus, 143, 297, 298. asterius, 4, 14, 17, 19, 42, 58, 64, 73, 74, 79, 154, 188, 184, 274, 275, 277, | 279, 280, 282, 283, 285-288, 293, | 299, 300, 301, 302, 303-305, 308— 312, 318, 329, 332-335, 342, 343, 371, 381, 384, 386, 388,389 (Pl. xi.; | Pl. xii. figs. 15-25; Pl. xiii. ; Pl. xvii. figs. 7, 8). basaltiformis, 300. beaugrandi, 286. blakei, 5, 14, 35, 50, 78, 280, 283, 284, 287, 288, 299, 319, 326, 328, 329, 330, 334, 342, 381-383, 386, SE) (uly, seosln cosets 1A) zeoctit) figs. 1-3). briareus, 274, 278, 280, 297, 302. briareus achalmianus, 297. briareus minutus, 278. briareus zollerianus, 297. bronnii, 323. buchsgauensis, 297. | caput-Meduse, 274, 278, 281, 300-302, | 304, 306, 308, 309. dargniesi, 297. decorus, 14, 18, 21, 35, 50, 51, 60, 77, 79, 91, 93, 95, 96, 100-102, 104, 105, 120, 123, 231, 279, 280, 283-285, 288, 290, 291, 293, 294, 299, 303-305, 308- 312, 316, 319, 320, 324, 326, 329, 330, 331, 332, 333-337, 341, 342, 379- 386, 388, 389, 402, 416 (Pl xxxii. figs. 4-6; Pls. xxxiv.-xxxvii.; Pl. lvii. figs. 2-5; Pl. lviii. figs. 1-3; Pl. lix. figs. 1-4; Pl. Ixii.). didactylus, 323, 327. dixoni, 143, 284. dubius, 294, 295. Jisheri, 34, 143, 284. jaccardi, 17. Johnsoni, 274. jurensis, 4, Pentacrinus maclearanus, 15, 19, 20, 35, 55, 62, 80, 277, 281, 282, 284, 285, 288, 299, 310, 812, 318, 315, 318, 323, 343, 346, 353,) 816; S8ie) OOo s elon (Ban yexvias Pl. xvii. fig. 1). milleri, 274. mollis, 44, 300, 3388, 339, 343, 378, 387, 389, 391 (Pl. xxxiii. figs. 7-10). miilleri, 14, 51, 55, 61, 77, 80, 277, 280, 285, 288, 299, 304, 305, 306, 307, 308-313, 315, 316, 318, 320, 323, 324, 330, 331-334, 337, 340-342, 380-385, 387-389 (Pls. xiv., xv.; Pl. xvii. figs. 9, 10). naresianus, 5, 14, 18, 21, 44, 50, 52, 53, 77, 78, 94, 128, 136, 140, 143, 184, 231, 240, 275, 280, 285-288, 290, 291, 293, 299, 300, 320, 322, 324, 325, 326-330, 334, 336, 337, 342, 354, 377, 378, 387, 389, 391 (Pl. xxvii. figs. 11— 13; Pls. xxviii—xxx.). nicoleti, 17. nodotianus, 297. pentagonalis personatus, 34, 284. psilonoti, 300. scalaris, 4, 35, 284. sigmaringensis, 300. subangularis, 274, 278. subteres, 270. tridactylus, 323. tuberculatus, 35, 274, 286. vulgaris, 294. wyville-thomsont, 14-17, 19, 21, 35, 44, 55, 76-78, 80, 91, 93, 98, 100, 119, 124, 129, 130, 136, 176, 185, 277, 280-284, 286-288, 290, 291, 293, 294, 299, 305, 310, 313, 314, 315-320, 322, 323, 335, 337, 342, 343, 346, 375, 387, 389-391, 415 (Pl. xvii. figs. 2-6 ; Pls. xviii.—xxiv.; Pl. lvii. fig. 1). | Pentremites, 192, 195, 413, 414. Pentremitide, 192. | Periechocrinus, summit of, 171, 172. Perisomatic skeleton, 1, 2, 73-85, 182. | Perisome, 67, 68, 97. | Perisomic plates, 39, 40, 41, 124. | Peristome, 68, 71, 84, 87, 164, 179, 181. | Peritoneum, 67, 99, 100. Philocrinus, 152-154. Phimocrinus, 150. REPORT ON THE CRINOIDEA. Phyllocrinus, 142, 216, 227, 413. Physetocrinus, summit of, 17 il Pigment, 23, 97. Picteticrinus, 273, 281. Pinnastella, 187. Pinnigrada, 187, 190. Pinnules, 55-66, 174; of Bathycrinus, 233, 234; of Comatule, 58, 59, 83; of Holopus, 207, 208 ; of Hyocrinus, 59-61, 219, 224; of Metacrinus, 10, 55, 58, 155, 341, 342; of Pentacrinus, 55, 58, 59, 155, 286; of Rhizocrinus, 56, 60, 255. Pisocrinus, 48, 54. Platyerinide, 61, 62, 149, 158, 160, 162, 170, 171, 175, 176, 178-181. Platycrinus, 24, 48, 62, 65, 146, 151, 155, 174, 176-179, 185, 196, 217, 258, 394. burlingtonensis, 177. ventricosus, 170. Pleurocystites, 20. Plexiform gland, 33, 34, 96-106, 108 ; 103, 104; of Antedon, 101, 102, 235; of Bathycrinus, 89, 90, 101, 235; of Echinozoa, 101, 105, 407 ; of Pentacrinus, 105; of Rhizo- crinus, 89, 101, 104. Plicatocrinide, 142, 222. Plicatocrinus, 49, 51, 142, 223, 289. Poteriocrinus, 46, 60, 61, 146, 224, 394. radiatus, 152. Primary interradial cords, of Bathycrinus, 126, 228— 230; of Enerinus, 125, 126; of Pentacrinus, 124-126, 228, 230, 292, 293; of Rhizocrinus, 126, 228-230, 252, 253. Proboscis, 41—44, 87. Promachocrinus, 36-38, 68, 90, 92, 97, 137, 138, 140, 144, 216, 403. abyssorum, 376, 377. kerguelensis, 98, 99, 101, 102, naresi, 378. Proximal plates of vault, 168-172. Psolide (orals of), 2 Pterocrinus, 242, 243. Pterotocrinus, 157, 177. Radials (first), 2, 3, 33-38, 48, 106, 152, 155, 157, 168-170, 393-395, 399, 402; of Bathycrinus, 3, 37, 230, 231; of Comatule, 147, 289, 293, 294; of Metacrinus, 48-51, 341, 357; of Pentacrinus, 289, 293,294; of Promachocrinus, 37, 38; of Rhizocrinus, 250-253. 163, 164, 223, 237, 152, 155, 205, 214, 222 ’ 127 167, 168, | | of Actinometra, 439 | Radials (second), 38, 47, 50; of Hudesicrinus, 10,215 ; of Holopus, 204-206, 215; of Metacrinus, 48, 341. Radial dome plates, 167, 169, 175-178. | Radial plug, 34, ae | Radial skeleton, 1, | Radial spaces, 31, 532. Radicular cirri, 27, 28. Ray-divisions, 47-51, 337. | Reparation of arms, 60, 255, 285; of disk, Reteocrinus, 42, 151, 181, 183-185, 371, 3 nealli, 43, 44, 184. richardsont, 43. stellaris, 43. subglobosus, 43. thizocrinus, 3, 24, 27-31, 38, 54, 64, 73, 109, 127, 130, 132, 142, 143, 151, 153, 213, 217, 222-226, 229-238, 244, 245, 246, 247-259, 268, 269, 289-292, 317, 371, 388, 391, 392; ambulacral plates of, 62, 261; arms of, 52-54, 64, 65, 267; calyx of, 33, 34, 36, 38, 248-253, 257; digestive tube of, 88-90, 254; geographical and bathymetrical range of, 136-141, 391, 392; intra-radial commissure of, 126, 253; orals of, 70, 72, 156, 219, 255; parasites of, 134; pinnules of, 56, 60, 255; plexi- form gland of, 89, 101, 104; primary interradial cords of, 156, 228-230, 252, 253; reparation of disk in, 255; second brachials of, 38, 254; stem of, 23-31, 107, 256; syzygies of, 5, 9, 254, 255; visceral mass of, 33, 90, 254, 255. lofotensis, 3, 25-28, 36, 47, 56, 72, 90, 93, 134, 136, 246, 248-251, 253, 254, 257, 259, 260, 261-266, 268, 374- 376, 378-380, 382, 384, 386, 388, 389, 391 (Pl. viiia. figs. 6 85 PlSixe figs 2 Pe excartioes sya): londinensis, 269. rawsoni, 25, 28-30, 47, 56, 72, 134, 249, 254, 255, 257, 258, 262, 263-269, 374-376, 379-384, 386, 388, 389, 391 (PI ix. figs. 3-5; Pl x figs. 3=20); Pl. liii. figs. 7, 8). calyx of, 265-267; pinnules of, young specimens of, 264, 265. Rhodocrinidw, 39, 40, 149, 164, 167, 168, 171, 174, 371. 2505. 72. 15 267 ; Rhodocrinites, 39, 40, 371. 440 Rhodocrinus, 371, 394. Root-joint of stem, 28. Rosette of Comatule, 34, 36, 106, 251, 291, 402; of Rhizocrinus, 34, 249, 251, 253. Saccosoma, 190, 195. Saceuli, 83, 127. Salenia, 395. Saumplittchen, 66, 74, 173, 174, 180. Scalpellum, 369. album, 134. balanoides, 134, 351, 355. Semiarticulata, 145, Side plates, 62, 66, 74, 79-83, 165. Solanocrinites, 272. Solanocrinus, 402, 403. Spongy organ, 98-101, 103, 406. Stelidiocrinus, 180. capitulum, summit of, 171. THE VOYAGE OF H.M.S. CHALLENGER. Testes of Hyocrinus, 220. | Tetracrinus, 216, 227. | Thaumatocrinus, 33, 34, 36, 39-42, 44, 45, 47, 58, 68, 70-72, 127, 144, 148-151, 156, 160, 166, 172, 179, 185, 223, 291, 270, 371, 372, 392; anal appendage of, 41, 45, 371-372; basals of, 34, 36, 371; calyx interradials of, 39-41, 371; geo- graphical and bathymetrical dis- ~ tribution of, 137-140; oral plates of, 70, 72, 160, 161, 371. renovatus, 149, 872, 878, (Pl. lvi. figs. 1-5). Thiolliericrinus, 24, 143, 257. Thylacocrinus, 371. Tiarechinus princeps, 414. Torynocrinus, 142, 377 Stem, 5-7, 12-32, 54, 114, 135, 194, 401; of Bathy- | Uintacrinide, 142. crinus, 23, 24, 26-28, 226; of Extracrinus, 276, 277, 287 ; of Hyocrinus, 5, 31, 32, 156, 218, 221; of Metacrinus, 14, 15, 17, 19, 287, 288 342, 343; of Pentacrinus, 12-33, 287, 288, 315-319 ; of Rhizocrinus, 23-31, 107, 256. Stemmatocrinus, 150, 152-154. Stilasterite, 187. Stomatocrinoidea, 147, 156, 195, 196. Strotocrinus, vault of, 171, 172. Stylifer, 134. Stylina, 134. Subambulacral plates, 75, 85, 165. Subangularen, 276, 278, 296. Support of Hudesicrinus, 214-216. Supra-nodal joint, 14. Symbathocrinus, 54, 158, 163, 164, 167, 169-171, 179. Synostosis, 2, 3. Syzygial interval, 52. Syzygy, 3-5, 8, 9, 15, 50, 52, 53, 231-233; of Coma- tula, 4, 53; of Pentacrinide, 4, 5, 254, 326; of Rhizocrinus, 5, 9, 254, 255. ‘alarocrinus, vault of, 177. Taxocrinus, 41, 42, 150, 151, 154, 211, 372. Tentacles, 56, 57, 63, 69, 75, 93, 115, 117, 189, 194, 416; of Holopus, 208. Tentaculata, 186, 189. Tegmen calycis. See Vault. Termination of stem in Pentacrinide, 18-23, 315-319. Tessellata, 142, 145-148, 191, 195, 196. 9 =9 Uintacrinus, 132, 142, 147-151, 196. Under-basals, 152, 153, 168, 169, 394-399, 402. Ungrooved arms of Actinometra, 56, 57, 69, 70, 113, 115. | Vascular axis of stem, 15, 23, 104, 107, 235. | Vault, 41, 42, 156, 157, 166-168, 185; of Actino- crinide, 164-167, 173, 180, 181 ; of Blastoidea, 173; of Coccocrinus, 160-163; of Cyatho- crinide, 173, 181; of Glyptocrinus, 183, 184; of Ichthyocrinide, 181, 182; of Platycrinide, 170, 171, 175-181; of Reteoerinus, 184; of Xenocrinus, 185. Vegetative system, 54-56. Ventral radial furrow, 252. Ventral sac, 44, 46, 76. Verruca, 349, 353, 355, 369. nitida, 134, fs Visceral mass, 1, 33, 67-70, 164, 166 ; of Bathycrinus, 33, 90, 234; of Rhizocrinus, 33, 90, 254, 255. Visceral skeleton, 85-87. Water-pores, 73, 75, 76, 81, 84, 92-96, 106, 194, 219, 220, 404-406. Water-tubes, 92-94, 106, 165, 236, 404. Water-vascular ring, 1, 92-94, 165, 405. Water-vascular system, 92-96, 106, 194, 406. | Water-vessels (radial), 1, 70, 92-94. Woodocrinus, 20. Xenocrinus, 42, 44, 181, 183-185, 371, 372. Zoroaster ackleyi, 399. Julgens, 106, 395, 399. Cd. chn. . EXPLANATION OF THE PLATES. The following letters are employed throughout all the Plates :— Axial cord of the ray or arm. Axial cord of a pinnule. Branches of the axial cord in the skeleton. Connective-tissue fibres between the anambulacral plates. The parambulacral extensions of the axial cords into the ventral perisome. Ambulacral epithelium. Primary interradial cords. Anambulacral plates. The secondary (radial) cords. Anal tube. Basal ring. First and second brachials. Radial blood-vessel. Ligaments uniting the basals to the top stem-joint, Plug of calcareous tissue in the radial funnel, called a rosette by Sars. The body-cavity or coelom. The bands of connective-tissue which traverse it. Fibrillar sheath round the vascular axis of the stem. Its radiating extensions. Coeliac canal. Interradial portion of the circular com- | missure. Cavities of the chambered organ. Their downward prolongations into the | stem. Fibres of connective tissue which traverse | J the fibrillar envelope of the chambered organ (central capsule). The nodal enlargements of the peripheral vessels of the stem (c/’). (zooL. CHALL. EXP,—PART XXXII.—1884.) cl, cu. . : Di, DeD,, é. Cirrus. Ciliated cups in the coeliac canal. Covering plates. Connective-tissue spaces in the perisome. Cirrus-vessel, Circumvisceral coelom. First, second, and fifth distichals. External epithelium. Fore-gut. Gut. Its epithelial lining. Genital cord. Genital canal. Genital vessel. Intervisceral blood-vessel. Intraradial portion of the circular com- missure. Arm-joint. Pinnule-joint. Interradial ligament. Basiradial ligament. Interbasal ligament. Dorsal ligament between the arm-joints. The fossa in which it is lodged. Interarticular ligament of the arms. The fossa in which it is lodged. Caleareous network in the perisome. Labial plexus. Its radial extensions beneath the ambu- lacra. Interarticular ligament of stem. Mouth, Muscle, Transverse muscle-threads in the water- vessels. Muscle-plate. Ti 56 442 THE VOYAGE OF H.M.S. CHALLENGER. ih . Ambulacral nerve. TaN te . Side plate. Mrs . Its oral ring. eS. . Subtentacular canal. Oh ye - Oral plate. sub. . . Subambulacral plate. Dae . Oral blood-vascular ring. Nee . Syzygy. ov. . . Ovary. UES aoe . Tentacle. P. orp. . Pigment granules, re . Testis. Des. Ws . Pinnule. CON es . Tentacular branch of water-vessel. hy, f,, 2,, First, second, and third radials. | V. or v Central vascular axis of stem. Tei, 4 . Kectum. | wry. . Ventral radial furrow. is . Muscles between the first and second) W. orw. . Radial water-vessel. radials, up. - . Water-pore. ite e . The fossz in which they are lodged. wr. . Water-vascular ring. TOs . Radial plug. Wt. . Water-tube. iste c . Radial space in the stem. |X. or. . Plexiform gland. Bh a . Spinelets on the disk. 4s 2 . Its ventral end which joins the labial Scene . Saceuli. . plexus. ih . Spongy organ. NOTES. 1. In the following lists there is a reference after each figure to a certain page of the Text. In the case of figures which illustrate entire specimens, the reference given is usually to the page in the systematic part of the Report on which the species is first described. But with those figures that represent structural details, reference is given to the page containing the explanation which the figure was designed to illustrate. This is sometimes in the morphological and sometimes in the systematic part of the Report. In a few cases there is no special reference to a figure in the Text; and the number of the page following its explanation is either that of the specific diagnosis ; or that of a page containing a description of structural peculiarities which is more or less illustrated by the figure in question. 2. The magnification given for those figures which were drawn before the collection of Stalked Crinoids came into my hands is in most cases only approximate (circa). A record was rarely kept of the amount of enlargement; and I have therefore estimated it as closely as possible. All the figures for which I am responsible, however, were drawn according to a definite scale, which varied according to circumstances, but was carefully noted in each case. 3. All the figures which were drawn for Sir Wyville Thomson, and also those on Plates LVII., LIX., and LX. were drawn on the stone in the natural positions of the specimens, so that they appear reversed in the Plates. This should be remembered in future attempts to identify the individuals here described as types; and also in reading the description of the anatomy of the disk in Chapter VI. * ERRATA. Plate VIla.—The figure of the radial axillary in the lower right-hand corner should be lettered “17” instead GF PIS? Plate VIIb.—In the upper part of fig. 6, “a” should be “a’,” as in the lower part. On the left of fig. 4, “2’ should be “ L.” Plates XI, XU., XIII, and XVII.— Instead of “ Pentacrinus asteria, L.,” read “ Pentacrinus asterius, Linn., sp.” (see p. 303). Plate XXL—Fig. 1 should be “1a.” Plate LX.—Fig. 6, “ad” should be “a'.” PLATE I. + Yo ae. EXP,—PART xxx11,—1884,)— li. : ae ieee te * i a PLATE I. Ho.opus RANGI, VOrbigny. * The largest specimen, . Fig. 1. The bivial side. Fig. 2. The trivial side. “ku8iqs0g 1IINVY SNdOT0H e I ~saerp dea over wopTEOL VA A Pars sw q L Id Paptoutyg “TaStATReUN ‘C-wtsI0 aSekon BUT PLATE IU. PLATE II. Ho.opus ranci, d’Orbigny. Diam. Page Views of the trivial and bivial sides of an individual which has lost three of the four bivial arms, . : : ; Ree.” 68) L99 Urinoaidea. rl 1 lod aa lo ad nal de ony us HOLOPUS RANQGII, D.Orb ie . ° ‘ (zooL. cuLAt EXP, —Ps Vig. Fig. Figs. bo 6. as (ous PLATE IIL. Hotopus rAneGt, d’Orbigny. . View of the cup from above after removal of two of the com- posite axillaries, . Interior of the cup of the specimen represented in Pl. IL, showing the oral plates. Two axillaries are supposed to be removed, . Slightly oblique view of the dorsal surfaces of an axillary and the attached first brachial, . . Dorsal aspect of an axillary, . Oblique view of its proximal face, Oblique view of the ventral sides of two united brachials, Proximal face of the second brachial, 13. Terminal faces of some of the large lower brachials, Figs. 14, 15. Terminal faces of some of the small outer brachials, Fig. 16. Portions of the pinnules, Diam. Page 203 208 The Voyage of H_ M.S"Challenger’ Crinoidea. Pl. TII WS Black del Huth, Lith Edin® HeORESOrP Uns AGING Gian Ie D'Orbigny. PLATE LY; Ho.orus ranet, d’Orbigny. Diam, Page . Side views of a young specimen, . ; sy SR alo) 203 Xe PLATE V. Honopvs RANG, d’Orbigny. Diam. Page Fig. 1. The articular facets of the radials viewed from above, sx 33 202 Fig. 2. Horizontal section of the radials, 2 mm. below the edges of the two bivial facets. This is an inferior view of the ring of united radials shown in fig. 1, : : = ae 200 Fig. 3. Vertical section through the lower part of the cup, . DZ 201 Fig. 4. Horizontal section through the lower part of the cup, about 5 mm. above the basal expansion, : ; ex 3 200 Fig. 5. The calcareous network forming the peripheral portion of the ») cup, : - ; : ; : ee eke) | =. 200 Shinty Fig. 6. The calcareous network forming the inner faces of the radials, x 45 | p, 200 ar) ~ Fig. 7. Portion of a horizontal section through the cup, showing the c a . 5 | «4 relations of the two kinds of network, . é . aX SIZ e200 a, Fig. 8. Ideal representation of the more regular network forming the | = outside of the cup, : : ; } Se GSOs 200 Figs. 9, 10. The youngest individual dredged by the “ Blake,” . x (20 204 Fig. 9. From the side. Fig. 10. From above. The Voyage of H.M:S."Challenger.” Grinoidea PLV a pe = oa v.S Black, del HOLOPUS RANGI, D'Orbigny. : PLATE Va, PLATE Va. Hotopus ranat, d’Orbigny. Diam Wig. 1. Ventral aspect of a decalcified arm, showing the ambulacral groove and one of its lateral branches, : ; Se Se NG Fig. 2. Side view of a decalcified arm, . ; , : ASU Fig. 3. Side view of an entire ray, ; : ; = Date Page 206 208 208 “XNOIGYO,G “HWONVY SNdO10H wandosfouvt unmmor-y Vv 4M - ‘WNT 49 T9q38eM 005 k 3 ; : eA 1d ¥eprouug nT ae resuerew ‘c'wtr ro e8ekon.aut ‘oop erfipel tye} tiy svi PLATE Vo. PLATE Vb. The Lettering is the same in all the Figures. A, Axial cord. | m. Muscle. ce. Coeliac canal. | ste. Subtentacular canal. ge. Genital cord. | T. Tentacle. j. Pinnule-joint. | w. Radial water-vessel. Zi. Interarticnlar ligament. Houorus RANGI, d’Orbieny. ? ime Diam. Page Fig. 1. Transverse section of a lower arm-joint, : : aad) 209 Fig. 2. The upper portions of three pinnule-joints, showing the arma- ture covering the bases of the tentacles, . : : «60 208 Fig. 3. The terminal portion of a pinnule showing the tentacular plates ; from a dry specimen, : : ¢ : =? poe JO) 208 Fig. 4. Inner aspect of an entire ray, showing the rolling in of the distal arm-joints, . : ; : : = a 1G 206 Fig. 5. Ventral aspect of an axillary and the lower part of an arm, showing the ambulacral groove, . : ‘ ee ue 206 TheVoyage of HMS Challenger.” Crmoidea. Pl Vb. aS 5° oye O55.2 oe . R857 00 1) Say & West delet lith ; Geo. West $ Sons imp HOLOPUS RANGI. D’ Orbigny. OG a ae oe PLATE Ve. hes) Fig. 1. Portion of an oblique section through an arm-joint and the base of a pinnule, . ; : : : Fig. 2. Transverse section of an arm-joint with attached pinnule, Fig. 3. Portion of a nearly longitudinal section of a pinnule, . Figs. 4-10. HyocrInus BETHELLIANUS, Wyv. Thoms. Fig. 4. Terminal face of a stem-joint, Fig. 5. Optical section of a piece of stem cut longitudinally, . Fig. 6. Portion of the disk, showing one oral plate and the anambu- lacral plates lying outside it, Fig. 7. Transverse section of a pinnule, Fig. 8. Terminal portion of a pinnule, mounted in dammar and seen in optical section, . Fig. 9. Portion of a dry pinnule about the end of the enlargement to receive the genital gland, . : : : Fig. 10. Lower portion of a pinnule, mounted in dammar and seen in PLATE Ve. The Lettering is the same in all the Figures. A, Axial cord of arm. Js. Interarticular ligament of stem. a. Axial cord of pinuule. m. Muscle. ae. Ambulacral epithelium. O. Oral plate. an. Anambulacral plate. ov. Ovary. C. Coelom. 7s. Radial space in stem. ca. Fibrillar sheath round vascular axis of stem. sp. Side plate. cc. Coeliac canal. , ste. Subtentacular canal. cic, Ciliated cup. T. Tentacle. cp. Covering plate. t. Testis. ge. Genital cord. v. Central vascular axis of stem. J, Arm-joint. w. Radial water-vessel. j. Pinnule-joint. wp. Water-pore. ld. Dorsal ligament. Figs. 1-3. Hoxopus rani, d’Orbigny. optical section, . : , . : Diam. xX. 26 26 Fig. 5. Upper face of fifth joint, ; pre. 220 27 Fig. 6. Upper face of ninth joint, . ; x. 26 27 Fig. 7. Upper stem-joint, . : : x LG 27 Figs. 8, 9. Middle stem-joints, : 4 : Sy, SEG Pall Figs. 10, 11. Lower stem-joints, : ao toe tals 27 Figs. 12-14. The basal ring, . : ; : : ee ce 226 Fig. 12. From above. Fig. 13. From the side. Fig. 14. From below. Fig. 15. Distal face of first radial, re la) 231 Fie. 16. Distal face of second radial, . . : = ee 8 231 Fig. 17. Distal aspect of axillary, =. : : , ee Sig ND 231 Figs. 18, 19. Distal and proximal faces of the fifth brachial, . vey 16 232 Figs. 20, 21. Proximal and distal faces of an outer brachial, . ots wks 232 Figs. 22, 23. BaTHYCRINUS CAMPBELLIANUS, 0. Sp. Figs, 22, 23. Proximal and distal faces of an outer brachial, . Bee SU) 232 1 This figure is wrongly lettered 7 on the plate. Crinoidea.Pl.Vila. TheVoyage of HM 5 Challenger’ Berjeau & Highley deleLlith PHC, dir Hanhart imp. BATHYGRINUS ALDRIGHIANUS, Sp.n. CAMPBELLIANUS, Sp.n ” ” | PLATE VIIb. The Lettering is the same in all the Figures. A. Axial cord of ray or arm, ZL. Interradial ligament. a’. Its branches. | 1. Basiradial ligament. B, Basal ring. li. Interarticular ligament. B,. First brachials. R,. First radials. ai. Primary interradial cords, Id. Dorsal ligament. C. Coelom or body-cavity. | R,. Second radials, c. Network of connective tissue within the coclom. | R;. Third radials. cco. Interradial portion of the circular commissure. re. Rectum. ch. Cavities of the chambered organ, | rm. Muscles uniting the first and second radials. Sg. Fore-gut. V. Vascular axis of stem. G. Gut, | x. Plexiform gland, BATHYCRINUS ALDRICHIANUS, Wyv. Thoms. Fig. 1. Vertical section of the calyx, with the lower part of the disk, Fig. 2. Horizontal section of the basal ring, . Fig. 3. Horizontal section of the calyx at the level of the basiradial suture, 4 : : 7 - a - Fig. 4. Horizontal section of the radial pentagon at the level of the circular commissure, Fig. 5. Horizontal section of the calyx, through the articulation of the first and second radials, 6.1 Horizontal section of the calyx, through the upper part of the second radials, ; g. 7.2 Horizontal section of the calyx, through the middle of the third radials, g. 8. Horizontal section of the disk, through the articulation of the first and second brachials, 1 Tn the upper part of this figure a should be a’, as in the lower part. 2 On the left of this figure / should be L. Diam. 20 45 45 20 20 Page 235 226 228 230 230 231 231 ; seryeau wh The Voyage of HMS. Challenger” & hley delet hth PHC. dir BATHYCRINUS ALDRICHIANUS, Spn Hanhart imp ie ’ PLATE VILL 4 = e : a9 Pe he HALL ea us 5 RSS aeetan. i » 57 - PLATE VIII. BATHYCRINUS CAMPBELL IANUS, 0. Sp. Diam. Page Fig. 1. Calyx and arms separated from the stem and basal ring, aK, OB 238 Fig. 2. The radials and arm-bases, —. aay eis : Ne 8 238 Fig. 3. Side view of one arm, . ; : : ; > 6 234 Fig. 4. Four of the lower arm-joints, from the side, . : <6 238 Fig. 5. Side view of a pinnule, mounted in dammar, . : Oe oe) 233 NV. B.—The magnification given above is only approximate, as it was not recorded at the time the Plate was drawn, though I have endeavoured to work it out subsequently. Crimoidea PI, VIII HAMS. Challenger he Voyage of P Huth, Lith™ Edrat Black, del. + Ss US NU BATHYCRI Perr ea) : Prawodl ages Wels enittish (Papigsig ce 4 ‘ BOWTIE ion te Sakae THEM as yy ‘ § ae ))0C™”C~*C PLAT VOT, ae os A. Axial cord of arm. | J, Arm-joint. a’, Its branches, 7d. Dorsal ligament. ae, Ambulacral epithelium. | li, Interarticular ligament. B,, Second brachial. | mp, Muscle-plate. b, Radial blood-vessel. | m. Ventral or ambulacral nerve. br. Plug of calcareous tissue, called a basal rosette by Sars. R,. First radial, ce, Coeliac canal, re, Rectum. cco, Interradial portion of circular commissure. 7m. Muscles uniting the first and second radials, cp. Covering plate, | ste. Subtentacular canal, G, Gut. T. Tentacle. ge. Genital cord. vrf. Ventral radial furrow. ge’. Genital canal. | W, Radial water-vessel, ico. Intraradial portion of circular commissure. | x, Plexiform gland, Figs. 1-8. Batuycrinus GRraciLis, Wyv. Thoms. Fig. 1. Head and upper part of stem, . Fig. 2. Middle part of stem, Fig. 3. Lowest part of stem, . 2 ; y 7 Fig. 4. Ventral portion of a transverse section of an arm, Fig. 5. An entire section through the middle of an arm-joint, . Figs. 6-8. RHIzOCRINUS LOFOTENSIS, Sars. Fig. 6. Horizontal section through the lower part of the radials, of which there are six, ; : : : P Fig. 7. Horizontal section of the calyx of the same individual at the level of the articular faces of the radials, . : Fig. 8. Horizontal section of the disk of a pentamerous specimen at PLATE VIIa. The Lettering is the same in all the Figures, the level of the second brachials, . A 5 : Diam. 10 10 10 285 165 35 35 40 Page 243 27 27 236 236 250 252 254 The Voyage of HM.S.‘Challenger” Crinoidea FI Villa. . } Berjeau & Highley.delet hth . PHC. dir. Hanhart imp. | I-3. BATHYCRINUS GRACILIS, WyTh. 4,5. BATHYCRINUS ALDRICHIANUS, Spn. 6-8. RHIZOCRINUS LOFOTENSIS, Sars. PLATE IX. Figs. 1, 2. Raizocrinus LOFOTENSIS, Sars. Fig. 1. An entire specimen, Fig. 2. The calyx and arms, Figs. 3-5. RuizocrInus RAWSoONI, Pourtales. Fig. 3. General view of an entire specimen with the exception of the lowest part of the stem,! Fig. 4. Portion of an arm, from the side, Fig. 5. Dorsal aspect of an arm, V.B.—The magnification is only approximate, as in Pl, VIII. Diam. 12 12 Page 259 259 262 60 60 1 This figure was drawn from a dry specimen, parts of which had shown a tendency to separate ; and the gaps had consequently been filled up with gum. In consequence of this the syzygy between the first two brachials of the middle ray was wrongly drawn as a muscular joint like that between the second and third brachials. It should have been represented as a simple line without any gap between the joints, like the syzygies in the remaining part of the arm. “Challenger.” c The Voyage of HMS at Stoo g —— > oe g r, " wn graphere AZ Johnston, Lith: Wks. ova: RHIZOCRINUS LOFOTENSIS, M. Sars. RAWSONI, POURTALES. » ” SS Piva wer ” o4, * Fy.9 PLATE X. The same Letters occur in both Figures. br. The plug of calcareous tissue in the centre of the radial funnel, which was called a basal rosette by Sars. vrf. The ventral radial furrows of the calyx. Figs. 1, 2. Ru1zocRINvs LOFOTENSIS, Sars. Two views of a calyx with three of the first brachials remaining 7 situ. Diam. Page Fig. 1. From above, : . ; ; : - was 252 Fig. 2. From the side, : 5 : : ; . Oo 266 Figs. 3-20. Ruizocrinus RAwsONI, Pourtalés. Fig. 3. Calyx of a specimen from near the Azores; side view, eae 1100) 267 Fig. 4. The same from above, : ; ee Ka 250 Fig. 5. The same from below, : x 15 25 Fig. 6. Calyx of a specimen from off pes with the first iearhials remaining in situ; from above, . F 2) x 16 254 Fig. 7. A similar view of the calyx of another co specimen which has undergone reparation. All the first brachials are visible and four of the small second brachials; while the centre of the cup is occupied by the oral plates, . x 10 255 Fig. 8. Calyx of another specimen from the Azores with the first brachials attached ; from above, . . ; eae 0 255 Fig. 9. Upper face of the top stem-joint of the Azores bislimesy repre- sented in figs. 3-5, ; é - Se aS 25 Fig. 10. Upper face of the fourth joint of Ae same stem, : xo 15 25 Figs. 11,12. Terminal faces of two joints from rather above the midllle of the stem ; fig. 12 representing that nearer the calyx, . x 15 26 Figs. 138, 14. Terminal faces of two joints from the lower part of the stem ; fig. 13 representing that nearer the root, . » 6. SS 26 Fig. 15. The root of a specimen from Havana, 4 ~ xia 257 Fig. 16. Two stem-joints with attached Forasnmniven (Truncatulina lobatula), E : ‘ . , 5 os SO 134 Fig. 17. Proximal face of an epizygal at an arm-syzygy, ; 5 ee le 254 Fig. 18. Distal face of the corresponding hypozygal, . : xl 254 Fig. 19. Dorsal view of the second and two following brachials, to dow the backward projection of the proximal face of the second brachial (an epizygal), x le 254 . 20. Side view of the upper part of the disk, tee rarhoval of one arm. The arms have separated from the cup at the syzygy between the first and second brachials, . : o) Sak aegis 255 The Voyage of HMS.‘Challenaer” Crinoidea. Pl. X Jerjeau & Highley del.et lith. PHC. dir 2 RHIZOCRINUS LOFOTENSIS, Saps 3-20 . RAWSON], Pourt Hanhart imp - 7 - . ; ; ' 7 - 2. we > : ; ran 7 , ‘ . * ¢ 4 Ty + ‘4 ot ' i ! 7 ; r P 6 é ‘ * i a vs iy SSE > at nS PCS SES Tat SS SSN Ww penaee IT. 2 Ct Py oy yO Vy, Li be SOD EVIE 3 JS cupiesrend rosueTTeqo, ¢) TREO hy ¢% Day” sw jo esrhon SUL re (A se CORPRET TT eas = > Cerrar : rm ttre o = iI

ie ei CP? Ss 4 i LPP >>> ee eS - SIP on S CS > Gj a 3} i on, a, Bi 5 La aS OS “hy oS at % <> < ae LER CE RATE CERN eee sy a hf id \: o > Bs. > os Ra 23 203 >. Qa — y <4 E Sa, Ci CMAEEE EMER p77, Bi 25 Cre 3 aid ZG IE ELLE Zp PSS = MELT SV. eee 14 Fig. 5. A nodal joint from the lower part of the stem; lower face, . x 4 ive Fig. 6. The same ; upper face, : : : : ‘sXe ee 17 Fig. 7. Portion of an internode from near the top of the stem, me fe 18 Fig. 8. Nodal and internodal joints from the lower part of the stem,. x 2 305 Fig. 9. Face of a young internodal joint, —. : : se BCH hoe 15 Figs. 10, 11. Faces of older internodal joints, . BN OC a at 17 Fig. 12. Terminal face of a pinnule-joint, ; : FS ed 10 Fig. 13. Termination of an arm, : aX 2 300 Fig. 14. One of the middle arm-joints and its pinnule, : ss Ree 286 Fig. 15. The ambulacral skeleton of an outer pinnule, eG i) Fig. 16. Ventral aspect of the basal joints of a lower pinnule, showing the development of its ambulacral skeleton, : - 1 & 20 79 Voyage of HMS. ‘Challenger’ Ge GE lead ett eine Sena Saree rok tS ree aay Hanhart imp PHC. dir PENTACRINUS ASTERIA, Linn . au & Highley del.et hth. PLATE XIV. PLATE XIV. PENTACRINUS MULLERI, Oersted. Natural size, p. 306. iHMS." he Voyage or T 7 = bap %, TSS SS ai =& QT quan & ath CHIC oy} a Bre OPM = ga aun euenl re Ke lack, del Oersted 7 MULLER] PENTACRINUS PLATE XV. PLATE XV. _ PENTACRINUS MULLERI, Oersted. Diam. _ Page Fig. 1. The calyx and arm-bases, : : ; x 2 311 Fig. 2. Another specimen with four radials, . ; : eames 12 Fig. 6. Lower or syzygial face of a nodal joint, - : a Oh ine Figs. 7, 8. The ends of two pinnules, showing the termination of the ambulacral skeleton ; from the side, 4 : a als 80 Fig. 9. The same; from above, : ; Pa 4) 312 ie Voyage of HM'S. Challenger’ Hanhart im; PHC. dir. PENTACRINUS MULLERI, Oersted . au & Highley delet lith PLATE XVI. PENTACRINUS MACLEARANUS, Wyv, Thoms. Diam Fig. 1. The entire specimen, . ; . : : exe Fig. 2, The end of a pinnule ; from the side, . ; : oe x) Ae Fig. 3. Ventral aspect of the basal joints of a pinnule, showing the ce) development of its ambulacral skeleton, . : Ni ee 80 A© 154} a & 2 oS. ax Crinoidea. Pl. XVI West Newma bene SB SS5555 wobscepesect WPUDEDEREES Sie Wild & C.Berjeau dei F The Voyage of H.M.S "Challenger : sp.n MACLEARANUS, PENTACRINUS fue any PLATE, XVI. rat . Lidge). pepe 4 nr PLATE XVII. Fig. 1. PENTACRINUS MACLEARANUS, Wyv. Thoms. . Arm-groove of Pentacrinus maclearanus, . ‘ Figs. 2-6. PENTACRINUS WYVILLE-THOMSONI, Jeffreys. . Ambulacral skeleton of a pinnule ; from the side, . The same, near the base of the pinnule ; from above, . The arm-groove and brachial ambulacrum, . Vertical section of a decalcified specimen. Much of the alimen- tary epithelium has fallen away. The lobulated organ to the right of the centre of the figure is the plexiform gland, The disk of a dry specimen, . Figs. 7, 8. Penracrinus AsTeRtus, Linn, sp. Ventral aspect of one of the lower arm-divisions, showing the ambulacral skeleton, . The arm-groove and brachial ambulacrum, Figs. 9, 10. Penracrinus MULLERI, Oersted. . The arm-groove and brachial ambulacrum, . The disk of a spirit-specimen, Diam. 12 12 Page 80 320 320 320 33 320 79 79 80 311 Crinoidea PI.XVIL. ” te Voyage of HMS Challenger ump. Hanhart P.H.C.Dir |. PENTACRINUS MACLEARANUS, Sp.n. 2-6 P.WYVILLE THOMSONI, Jeffreys, pjeau & Highley del,etlith 7,8.P.ASTERIA,L..9,10.P MULLERI, Jersted PLATE XVI. 4 PLATE XVIII. PENTACRINUS WYVILLE-THOMSONI, Jeffreys. 1. The head, with the upper part of the stem, 2. The calyx and arm-bases, 3. A young specimen, gs. 4, 5. Upper and lower views of the radial pentagon, os. 6, 7. An isolated basal from below and above, 8, 9. Proximal and distal faces of the third (axillary) radial, . 10,11. Proximal and distal faces of the second radial, Diam. 4 ) 2 3 3 Page 313 320 21 30 293 50 50 Crinoidea. Pl. XVIII. The Voyage of H.M.S."Challenger” F Huth,lnth™ Edin® S Black, del. Jeffreys WYVILLE -THOMSONI, PENTACRINUS SS Sr ES SSS ee ae Le eR ee RE SE FRETS ES a Es, PLATE XIX, ’ PLATE XIX PENTACRINUS WYVILLE-THOMSONT, Jeffreys. Vig. 1. An entire specimen, . Fig. 2. Portion: of an internode from near the top of the stem, See fas iy | Fig. 3. Nodal and internodal joints from the upper part of the stem. . a 4 Fig. 4. Nodal and pees joints from the dower part of the stem, . pe: 4 Fig. 5. Portion of an internode from the lower part of the stem, ele ; x eA Fig. 6. Interradial view of the calyx and arm-bases, ae Fig. 7. Radial view of the same parts in another specimen, an = HA ee oe | J « we a Ri Re ’ Ne one wi sc " a — a a : sy . Rit i= Au Riss mt. @@) san ius) ean» Be PLATE XX. PENTACRINUS WYVILLE-THOMSONT, Jeffreys. Diam. Page Figs. 1-3. The ring of united basals, . 4 : : eg it) 282 Fig. 1. From below. Fig. 2. From above. Fig. 3. From the side. Fig. 4. The central plug of limestone network within the calyx; from above, : : : 3 : ; aXe O 34 Fig. 5. The same ; from below, : : : ; aay ee eO 34 Fig. 6. Interior view of the calyx, after removal of two radials and one basal, . ‘ ; ; : . J ESz Al) 34 Figs. 7-9. The ring of united radials, . : ; pe ee si K(0), 33 ea . 7. From the side. a . 8. From above. a oO (=) oO to) g. 9. From below. Crinoidea The Voyage of H.M.S. "Challenger West lith W.B.C. dir West Newman PENTACRINUS WAY VIP EEE = ii OMS:OiN I PLATE XXI. PENTACRINUS WYVILLE-THOMSONI, Jeffreys. . A third or axillary radial, a. Distal face, b. Side view, c. Dorsal view, d. Proximal face, . e. Ventral surface, . A second or axillary distichal, ot t. Distal face, b. Side view, d. Proximal face, . c. Dorsal view, e. Ventral surface, . A first distichal, a. Ventral surface, b. Proximal face, . . A first brachial, : a. Ventral surface, b. Proximal face,.. ; : : c. The proximal face of another specimen, . A second radial, a. Distal face, b. Ventral surface, c. Proximal face, . . A first radial, . a. From beneath, . b. Side view, c. From above, d. Distal face, . An isolated basal, a. From beneath, . b, Side view, Diam. 10 10 10 10 10 10 10 313 PENTACRINUS WYVILLE-THOMSONI, PLATE XI. les} SS} des) es] So sie yates me ge oe ge PLATE XXII. PENTACRINUS WYVILLE-THOMSONI, Jeffreys. 1. One of the upper stem-joints, . 2. The top stem-joint of a young specimen with a smaller one in- terpolated above it, 3. A small interpolated joint, 4, Another interpolated joint, somewhat younger, 5. An older joint from the upper part of the stem, with an impres- sion on its upper surface in which rested the young joint shown in fig, 4, 6. The upper face of a young nodal joint, 7. A young internodal joint, 8. A somewhat older internodal joint, gs. 9-12. Young internodal joints from the growing part of the stem, with smaller ones interpolated above them at different stages of development, . 13. An older, but still immature internodal joint, . 14. A young internodal joint from the upper part of the stem, . 15. Upper face of a young nodal a from the upper a of the stem, g. 16. Lower or syzygial face of a nodal idee from the middle of the stem, . 17. Lower face of a supra-nodal joint from the upper part of the stem, . 18. Upper face of the comepeudee nodal joint, Figs. 19-24. Mature joints from a little below the middle of the s . 19. Upper face of a nodal joint, 20. Its lower or syzygial face, . 21. The upper face of an infra-nodal joint, 22. Its lower face, . : . 28, 24, Ordinary internodal joints, 5, 26. Old internodal joints from the lowest part of the stem, . 27. An enlarged nodal joint from the end of the stem with its lower face rounded and the central canal closed up, 28. Portion of the calcareous network forming the substance of the stem-joints, Diam. xO 15 ae 1110) x alo be a a Shader Berjean& Highley delet lith . PHL. dir. Hanhart imp. PENTACRINUS WYVILLE-THOMSONI, Jeffreys . PLATE XXY. PENTACRINUS ALTERNICIRRUS, 0. sp. Diam. Page Head and upper part of stem, : : : ; x 2 321 Crinoidea. Pl. KXV he Voyage of H.M.S."Challenger” /] J vy Ve By! a) J F Huth, Lith? Eadie” S. Black, del AEDT ERNIC LR RUS, Sprn- PENTACRINUS AY PLATE XXVI. PENTACRINUS ALTERNICIRRUS, 0. Sp. Diam. Page Fig. 1. The disk, : : . . : 5 exes 77 Fig. 2. The anal interradius, enlarged, ; ; a as as Figs. 3,4. Inner and outer surfaces of the two outer radials with the distichals and palmars attached, . : : See as 50 Figs. 5,6. The third or axillary radial, : : 3 OS 5 Fig. 5. Proximal face. Fig. 6. Distal face. Figs. 7,8. The second radial, . ? : ; : * =Xeo 5 Fig. 7. Proximal face. Fig. 8. Distal face. Fig. 9. The lower face of a first radial, with one basal remaining attached, . ‘ : ; : : a 293 Fig. 10. Distal face of a first radial, : ee ne 9 Fig. 11. The calyx from below, : : , ; UPS 33 Fig. 12. Side view of a nodal and infra-nodal joint in their relative positions, . : : : : 3 ee oe 13 Figs. 13, 14. Upper and lower faces of a nodal joint, . . x 4 323 Figs. 15, 16. Upper and lower faces of the infra-nodal joint, —. tka oe 13 Fig. 17. Faces of internodal joints, ‘ : , : a Na 12 Fig. 18. Various stages in the development of internodal joints, Lae 12 e Voyage of H.M.S'Challenger” Crimoidea. Pl. XXVI I ack, del ¥ Huth, Iath? Edin® PAESNGAIG RIN US AG IGESRoN SEG HbR OES) Sipsn aS —— PLATE XXVII. (ZOOL, CHALL, EXP,—PART Xxx11,—1884,)—li. PLATE XXVII. Figs. 1-10. PENTACRINUS ALTERNICIRRUS, 0. sp. Fig. 1. Portion of stem containing two nodal joints; interradial view, Fig. 2. Lower or syzygial face of a nodal jomt which bears three clrri, Fig. 3. The corresponding face of a jot bearing only two cirri, Fie. 4. The ambulacral skeleton of a pinnule ; from above, Fig. 5. The end of a pinnule ; from the side, . Fig. 6. The arm-groove and brachial ambulacrum, Figs. 7, 8. Inner and outer sides of an arm, bearing a pinnule-cyst of Myzostoma deformator, von Graft, Figs. 9,10. Inner and outer sides of an arm, modified by a cyst of Myzostoma pentacrin, von Graft, Figs. 11-13. PENTACRINUS NARESIANUS, 0. sp. Fig. 11. The ambulacral skeleton of a pinnule ; from the side. Some of the covering plates have been removed, Fig. 12. The same; from above, Hig, 13.) the brachial ambulacrum ; from above, Diam. 6 Page 270 323 323 323 80 80 324 324 78 78 78 Crinpidea. Pl. XXVII he Voyage of H.M.S,Challenger” rere >i peeegacrre acass5s9s a —_——— — 13 Hanhart imp PHC. dir I-10. PENTACRINUS ALTERNICIRRUS, Spn rjeatt & Highley delet lith NARESIANUS, Sp.n Pd I-13. PLATE XXVITI. Fig. 1. The head, Fic, 2, The stem PLATE XXVIII. PENTACRINUS NARESIANUS, h. sp. F Huth, Litht Edin® Crinoidea. Pl. XXVIII e Voyage of H.M.S SEs Yyonye os Leal in Dau : A SS” = ze p a a Z, catl rida oe a . 7 = De cig simu einlie MUMLLM Gligaie nat { aD Cis as Oe aAS ed Reem = Se A a oe = => ike (| § recent eee ey wt WS. Black, del Sp.n NARESIANUS, PENTACRINUS Se) _ - PLATE XXIX. (ZOOL. CHALL, EXP.—PART XxxuI,—1884.) —Ii, PLATE XXIX. PENTACRINUS NARESIANUS, Nl. Sp. Diam g. 1. The calyx and lower parts of the arms of an adult individual,. x 2 Fig. 2. A young individual, x 14 oidea. Pl] KXIX Crin e Voyage of HM S"Challenger” rd ro ra] cA mo Sp.n NARESIANUS, PENTACRINUS ir PLATE XXX. PLATE XXX. PENTACRINUS NARESIANUS, 0. Sp. Fig. 1. The calyx and lower parts of the arms of an adult individual, . Fig, 2, The disk; : P : : : é : Figs. 3, 4. The calyx ; from above and below, . Fig. 5. The lower face of a first radial, with one basal remaining attached, Figs. 6, 7. An isolated basal from below and above, Fig. 8. A first radial, from beneath, Fig. 9. Distal face of a first radial, Figs. 10, 11. Proximal and distal faces of a second radial, Figs. 12, 13. Proximal and distal faces of a third or axillary radial, Fig. 14. Dorsal aspect of the axillary with the two first brachials attached, . , ‘ ‘ é ; Figs. 15, 16. Proximal and distal faces of a first brachial, Figs. 17, 18. Proximal and distal faces of a second brachial, Figs. 19, 20. Proximal and distal faces of the hypozygal portion of the third brachial, Figs. 21, 22. Proximal and distal faces of the corresponding epizygal, . 23. Portion of an arm containing two syzygies ; side view, Fig. 24. The arm-groove and brachial ambulacrum ; from above, Fig, 25. Terminal faces of an internodal joint, . Figs. 26, 27. Lower and upper faces of a nodal joint, Figs. 28, 29. Lower and upper faces of an infra-nodal joint, Fig. 30. The two faces of the next joint below an infra-nodal, Diam. Page 326 a, ae VINE GAN sinh Fa sy ¥ Huth, Lid® Edint Black, del. Sp. n. NPANRBESelA NOU CS., PoE NGA GR LIN US PLATE XXXa. {Z00L. CHALL. EXP,—PART XXXIL.—1884,)—lTi. PLATE XXXa. PENTACRINUS NARESIANUS, 0. Sp. Fig. 1. The youngest specimen obtained, Fig, 2. One of its internodal joints, Fig. 3. One of its nodal joints; upper face, Figs. 4, 5. Two fragments, probably from the lower part of the stem of this specimen, . Fig. 6. Portion of a full grown stem, . Fig. 7. One of its internodal joints, Fig. 8. The inner.face of an arm from the third to the eighth brachials, Figs. 9, 10. Two syzygial joints from the arm of a young individual, as seen from the side (fig. 9) and from above (fig. 10), a. The epizygal. b. The hypozygal. Figs. 11, 12. Similar views of a full grown syzygial pair, Diam. 10 10 Page 327 291 291 327 327 PHC dir PENTACRINUS NARESIANUS, S aid ae el sl a i ft i ar sy OD.ii PLATE XXXI. PLATE XXXI. PENTACRINUS BLAKEI, P. H. Carpenter. Diam. Fig. 1. An entire specimen, : , : ? : . nat. size Fig. 2. The calyx and arm-bases, : , aXe gee SH) Xero x 25 ae ft) x 75 Page 330 337 309 309 33 336 16 ern Midas & ON The Voyage of HM.S "Chal F Huth, Lith* Bdin* aoa Wy. Th DEENG JO UROUES., i 1S % Fre, & q es sti PENTACRINUS Black, del PLATE XXXY. PLATE XXXV. PENTACRINUS DECORUS, Wyv. Thoms. Fig. 1. The youngest specimen obtained by the “ Blake,” Fig. 2. A slightly older individual, +: Lrinoid Challenger” « heVoyage of HM.S - t “J SP g oo : ( ree a Le PHC. cir PENTACRINUS DECORUS, Wy.Th Jeryeau bc Highley delet lith i PLATE XXXVI, (ZOOL, CHALL, EXP,—PART xxxi1,—1884.)~-Ii PLATE XXXVI. PreNTACRINUS DECORUS, Wyv. Thoms. Diam. Page Fig. 1. Calyx and arm-bases of a premature individual with large to) basals, A : : : : é ue 336 Fig. 2. The lower part of the stem of the same specimen, eon et 335 Fig. 3. Calyx and arm-bases of another young individual with small basals, 5 : ; : ; : Re oe! 336 Crinoidea.Pl. XXXVI TheVoyage of HM.S ‘Challenger” oe PER A onan — = a 3 2 Te Se OP ND, ae Prt a ne | ewer ‘ea imiidunane ABTS ig dt gnae f mod poe c. see ps CLOTS a & en ae henewe oy ? Sas mike: ST 4 2 ‘e Ss S re me = ch ort C : ee, (Se ay ay pay Dy re Q>

  • o V LLISELILLLLL ITT 2 © OST awe 0 f i ats Wy 5 x { (( 2 z annie tise TL IIS ITLILL 27 7) a CLE E ey S imp PHC. dir METACRINUS MURRAY, Spn et lith del Highley « erfeau PLATE XLIII. METACRINUS NOBILIS, n. sp. Diam. Page ig. 1. The stem, : : ; ; ; : sean 352 . 2. The calyx and arm-bases, : ; : PL ee 341 ig. 3. The disk, : : : eee Se 342 ig. 4, Portion of a ray, : : , ; Vie 2 341 idea. P]_ XLII nger M.S "Challe The Voyage of H => F.Huth, Lith® Edin? Black, del n Sp c NOBILIS, VEER AG REN US &_-} to SE EO ee PLATE XULLY. (gooL. CHALL, BXP,—PART xxx11,—1884,)—h. g. 1. The stem, Fig. 2. The calyx and arms, PLATE XLIV. METACRINUS VARIANS, 0. Sp. The Voyage of H.M.S."ChallenSer.” Af. SS Wie ES WU Sgres BOF 7 Nm Lie eee ARG Sean Sarre Feet as TASS N . - eer SPs LOTS TTT, OCT, oe F RO Rep So7, ae mss! F. Huth, lath’ Edin® ck del fS.Bla NAT RSIVAGNS:= Sp. a MEESIPAIG Rol NUS PLATE XLY. PLATE XLV. METACRINUS MOSELEYI, 0. sp. Diam. Page Fig. 1. A young individual, . 5 . nat. size 356 Fig. 2. An internodal joint, . : : ; : = Xe imees 357 Fig. 3. The upper or syzygial face of an infra-nodal joint, — . Pee Sei 357 Figs. 4, 5. Upper and lower faces of a nodal joint, —. : SERED 357 Fig. 6. Portion of the stem, . , : : : ok 4 357 Fig. 7. Portion of an arm, with commencing Myzostoma-cyst, 5. i pe 358 be) MYT SIT stanaye xe ee LL Sebel lal Ts STU ala Ls Cert oir = 2a; +5 } y YD f METACRINUS MOSELEYI, PLATE XLVI. (ZOOL. CHALL, EXP,—PART xxx1L—1884.)—Ti PLATE XLVI. METACRINUS MOSELEYI, n. sp. Diameter 21 (circa), p. 357. idea The Voyage of H.M.S."Challenger.” 4 . "i (i AN vane iaoaange™ { iia aT} wane Pr daldddade * peneee ge 6nileee: fi ins on % i - res Imp } Hanhar INTERRUPTUS, Sp.n METACRINUS 3erjeau é& Highley del.et lith PLATE LIL. “N ee) PLATE LIL. Figs. 1-6. METACRINUS TUBEROSUS, n. sp. Portion of the stem, Lower face of a supra-nodal joint, . Upper face of a nodal joint, . An ordinary internodal joint, . Lower face of an infra-nodal joint, Side view of a nodal joint and the two upper joints of the in- ternode below it, . Figs. 7, 8. Rutzocrrnus RAWSONI, Pourtalés. . A young specimen with the arm-bases slightly displaced at the syzygy between the first and second brachials, . The upper part of the stem, with the calyx and first brachials of a slightly older individual, Diam. 20 20 Page 369 370 369 369 370 369 265 266 |-6. METACRINUS TUBEROSUS, Spn 7,8. RHIZOCRINUS RAWSONI, Pourtalés PLATE LIV. (ZOOL CHALL, EXP.—PART XXxi.—1884.)—li. PLATE LIV. Figs. 1-4. ANTEDON ACGLA, n. sp. Diam, Page Fig. 1. Ventral aspect of a portion of an arm from its lower third, . x 7 83 Fig. 2. Side view of one of the genital pinnules, : 1 83 Fig. 3. The ventral surface of another genital pinnule, : « 369 EO 83 Fig. 4. The ambulacral skeleton of a later pimnule with the covering plates closed down, : : : : oe 20 83 Fig. 5. ANTEDON ANGUSTICALYX, n. sp. Fig. 5. The ventral aspect of an ungrooved genital pinnule, . Fok ms 83 Figs. 6, 7. ANTEDON INCERTA, N. sp. Fig. 6. Side view of a genital pinnule with its ambulacrum, . = ey alles 83 Fie. 7. The ambulacral skeleton of an arm and the lower parts of the pinnules, . < : : . : x 4D 83 Fig. 8. ANTEDON INAQUALIS, n. sp. Fig. 8. The ambulacral skeleton of a pinnule ; from the side, . a a XO) 83 Fig. 9. ANTEDON BASICURVA., n. sp. 9. Side view of the ambulacral skeleton of a pinnule mounted in dammar, . : ; ; : : pea tS () 83 Figs. 10, 11. ACTINOMETRA STROTA, n. sp. Fie. 10. The peristome of a dry disk, with the origins of the ambu- lacra, : , : ; : 5 nna 3 85 Fig. 11. Vertical section of an ambulacrum of a dry disk, : 3 x ae 85 he Voyage of H.M.S. “Challenger” Crmoidea.P1. LIV. cauk&Highley del et lith PHC du |-4. ANTEDON ACOELA. 5. ANT. ANGUSTICALYX. 6.7 ANT. INCERTA. 8.ANT. INAEQUALIS. 9. ANT. BASICURVA. 10,11. ACTINOMETRA STROTA. Hanhart imp PLATE LY. PLATE LV. Disks oF CoMATUL. Diam. Page Fig. 1 Disk of Actinometra jukesi, n. sp., ‘ : : ee ce 85 A small Isopod is visible within the anal tube (see p. 133). Fig. 2. Disk of Actinometra strota, n. sp., : ; : a wane 2 85 One of the posterior arms is replaced by two pinnules (see p. 60). Figs. 3, 4. Disks of Antedon multiradiata, n. sp., } ‘ a 4 84 Fig. 5. Disk of Antedon acela, n. sp., . : : ; cx, 0 84 Fig. 6. Disk of Antedon angusticalyx, n. sp... ; ; og Slo 84 Fig. 7. Disk of Antedon basicurva, n. sp., : : ; (2 oD 84 Pl. LV Yinoiaea £ r es to NI oN} 4 vA a i) gs ON ) op.z 2.ACTINOMETRA STROTA,Spn 5.ANTEDON ACOELA, Sp n. ‘= ’ v ’ ACTINOMETRA JUKES| 3,4. ANTEDON MULTIRADIATA joly 7.ANTEDON BASICURVA, Sp.n spn 6. ANTEDON ANGUSTICALYX PLATE LVI, (ZOOL. CHALL, EXP.—PART XXXx11,—1884,)—Ti. Fig. Fig. Fig. PLATE LVI. Figs. 1-5. THaumMatocrinus RENovaATUS, P. H. Carpenter. Diam. Figs. 1, 2. Side views, radial. In fig. 1 the right anterior, and in fig. 2 the right posterior ray faces the observer, . ah hake ke 3. Side view, interradial, ; ‘ 3 : ea xenaal 4. The anal side, . : : ; ; E> Say 5 5. The disk, : : F : : : elise. Bley Fig. 6. ANTEDON RosAcEA, Linck, sp. 6. An abnormal disk with two mouths, . : é Rhea 5 Fig. 7. ACTINOMETRA MAGNIFICA, 0. sp. 7. The disk of the only specimen known, : . nat. size Fig. The course of the water-vessel which supplies the arms of the posterior ray is marked by a fine line upon the surface of the disk, but it is not accompanied by any food-groove. Fig. 8. ACTINOMETRA STELLIGERA, l. sp. 8. An abnormal disk with two mouths and two anal tubes, un CEN 5 56 he Voyage of HM.S."Challenger” Crimoidea.Pl. LVL Berjeauk Highley del. ot lith P.H.C. dir Hanhart imp 1-5. THAUMATOCRINUS RENOVATUS, Sp.n. 6.ANTEDON ROSACEA, Linck, Sp 7. ACTINOMETRA MAGNIFICA,Sp.n. 8.ACTINOMETRA STELLIGERA,Sp.n rane PLATE LVII. Fig. ny A Fig. Fig. IL PLATE LVI. The Lettering is the same in all the Figures. we. Ambulacral epithelium. an. Anambulacral plate. 6. Radial blood-vessel. c. Connective tissue meshwork in the coelom. cp. Covering plate. eve. Cireumvisceral coelom. fg. Fore-gut. g. Epithelial lining of the gut. gv. Genital vessel. ib. Intervisceral blood-vessel. p. Labial plexus. lr. Its radial extensions beneath the ambulacra. n. Ambulacral nerve. p. Te. Pigment granules. Rectum. Spinelets on the disk. . Side plate. . Subambulacral plate. . Tentacle. . Tentacular branch of water-vessel. . Radial water-vessel. . Water-pore. Water-tube. . Plexiform gland. rv. Its ventral end which joins the labial plexus. Fig. 1. PENTACRINUS WYVILLE-THOMSONI, Jeffreys. Transverse section of the disk in the anal interradius, showing the labial plexus (Jp) and its extensions beneath the am- bulaera (Ur), Figs. 2-5. Prnracrinus pEcorus, Wyv. Thoms. Vertical section through the outer part of the plexiform gland, showing its connection with the intervisceral blood-vessels, — x The upper part of a longitudinal vertical section through the disk, showing the connection of the labial plexus (/p) with the genital and intervisceral vessels (gv, 7b), and also with the ventral end of the plexiform gland (av). section cuts the edge of the anal tube (re), but passes to the right of the mouth, Diam. x 40 100 The x 30 Transverse section of an ambulacrum near the peristome. This shows the two lateral water-vessels (w), which are separated by the radial extension of the labial plexus (Ir), x 50 . Portion of a vertical section through the periphery of the disk, showing the intervisceral vessels on the outside of the digestive canal, 2 a eeOO Page 100 101 93 102 The Voyage of HMS. “Challenger.” 1. PENTACRINUS WYVILLE—THOMSON|I 2—5. PENTAGRINUS DECORUS, Wy ville J Jeffreys : Thomson. Crmoidea, Pl. LVI. Goo West & Sons del lith et amp PLATE LVIII. The Lettering is the same in all the Figures. ai. Primary interradial cords. 7. Basiradial ligament. ar. The secondary (radial) cords. 7b. Interbasal ligament. B. Basal plate. In. Limestone network in the perisome. ic. Bands of connective tissue in the body-cavity. | ls, Interarticular ligament of stem. ch. Cavities of the chambered organ. p. Pigment granules. ch’. Their downward prolongations into the stem R’, First radial. e. External epithelium. re, Rectum. Sg. Fore-gut. rp. Plug of calcareous tissue within the radial funnel. G. Gut. V. Central vascular axis of stem. ib. Intervisceral blood-vessel. X. Plexiform gland. Z. Interradial ligament. | Figs. 1-3. Pentacrinus pecorus, Wyv. Thoms. Diam. Page 1. Horizontal section through the lower part of the calyx, showing the bifurcation of the primary interradial cords (a7) in the basals, : ; : ; : an 4 () 124 2. Horizontal section through the lower part of the radial pentagon, showing the upward extensions of the cavities of the chambered organ (ch), : : . oo Sho 105 3. The central part of a median vertical section through the calyx, showing the chambered organ and its connection with the vascular axis of the stem, E : : 1x40 104 Fig. 4. PENTACRINUS NARESIANUS, 0. Sp. 4. Portion of a horizontal section of the disk, showing the position of the plexiform gland (X) between the fore-gut and the rectum, . : : ; ; ; cee coe 101 Figs. 5, 6. PROMACHOCRINUS KERGUELENSIS, 0. sp. 5. Portion of a horizontal section of the disk, showing the plexi- form gland (X), . : : ih hes ss. SSE 101 6. A similar section nearer the calyx, . : ; y x as 101 The Voyage of H.M.S “Challenger” Crmoidea.. Pl. LVIIL Berjeau & Highley del et ith P.H.C. dir I-3. PENTACRINUS DECORUS, Www. Th. 4. PENTACRINUS NARESIANUS, Sp.n 5,6. PROMACHOCRINUS KERGU ELENSIS,Spn PLATE LIX, PLATE LIX. The Lettering is the same in all the Figures. . Connective tissue fibres between the anambulacral plates. . The parambulacral extensions of the axial cords into the ventral perisome. . Ambulacral epithelium. . Radial blood-vessel. . Bands of connective tissue in the body-cavity. . Covering plate. . Circumyisceral coelom. . External epithelium. Sg. Fore-gut. G. Gut. g. Its epithelial lining. . Genital vessel. . Labial plexus. . Ambulacral nerve. . Pigment granules. . Spinelets on the anambulacral plates of the disk. . Saceuli. 0. Spongy organ. . Side plate. Subtentacular canal . Tentacle. . Tentacular branch of water-vessel. . Radial water-vessel. . Water-pore. . Water-tube. . Plexiform gland. . Its ventral end which joins the labial plexus. Figs. 1-4. Penracrinus Decorus, Wyv. Thoms. Diam. Page Fig. 1. Transverse section of a brachial ambulacrum, x 100 96 Figs. 2-4. Vertical sections of some of the ambulacral plates of the disk, which bears spinelets and are traversed by fibres of the parambulacral nerve-plexus (ad), x 150 124 Fig. 5. ANTEDON Rosacea, Linck, sp. Fig. 5. Vertical section through the left or eastern angle of the peristome, at the origin of the two lateral ambulacra, showing the labial plexus (/p) and water-tubes (wt), eh) 98 Figs. 6, 7. ANTEDON ESCHRICHTI, Miill., sp. Figs. 6, 7. Portions of vertical sections of the disk in the neigh- bourhood of an ambulacrum, showing the parambulacral nerves (ad), x 100 123 Figs. 8, 9. PROMACHOCRINUS KERGUELENSIS, n. Sp. Fig. 8. Portion of a vertical transverse section of the disk behind the mouth, showing the spongy organ (so) at the side of the fore-gut (fg), x, 20 99 Fig. 9. Portion of another section of the same series, but in front of the mouth, showing the upper end of the plexiform gland (x), part of which is becoming reticular and spongy (xv), x 30 99 he Voyage of H.M.S."Challenger.” Crinoidea. Pl. LIX. Goo West & Sane del Lith et imp 1-4. PENTACRINUS DECORUS, WyvilleThomson. 5.ANTEDON ROSACEA, lainck, sp. 6,7. ANTEDON ESCHRICHT!, Miull.sp. 8, 9. PROMACHOCRINUS KERGUELENSIS, Sp.n. oa PLATE LX. - PLATE LX. The Lettering is the same in all the Figures. a’. Ventral branch of the axial cord of the arm. | gv. Genital vessel. ad. The parambulacral extensions of the axial-cords into the | ib. Intervisceral blood-vesse ventral perisome of the disk, lp. Labial plexus. ae. Ambulacral epithelium. | nm. Ambulacral nerve. b. Radial blood-vessel. nr. Its oral ring. c. Bands of connective tissue in the body-cavity. p. Pigment granules. ec. Coeliac canal. sa, Sacculi. eve, Circumvisceral coelom. | so. Spongy organ. e, External epithelium. ste. Subtentacular canal. z Sg. Fore-gut. tb. Tentacular branch of water-vessel. g. Epithelium of the gut. | w. Radial water-vessel. ge. Genital cord. wp. Water-pore. gc’. Genital canal. | wt. Water-tube. Diam. Fig. 1. Transverse section of an ambulacrum behind the mouth, show- ing the connection of the genital vessels (gv) and labial plexus (/p), : : ; ; ee Pe) Fig. 2. Anrepon carrinata, Leach, sp. Fig. 2. Portion of a vertical transverse section of the disk in the anal interradius, showing the connection of the genital vessels (gv) and labial plexus (/p), : . bd 28a Figs. 3-6. ANTEDON ESCHRICHTI, Miill., sp. Fig. 3. Portion of a vertical longitudinal section of the disk, which passes through the peristome, showing the connection of the intervisceral vessels (‘b) with the spongy organ (so), . x 35 Fig. 4. Longitudinal vertical section of the peristome in the direction ofaray, . : : : : 2:5) X* NGO Fig. 5. Part of a vertical transverse section of the disk in the anal in- terradius, showing the spongy organ and labial plexus, . x 40 Fig. 6. Transverse section of a brachial ambulacrum, showing one of Fig. 1. ACTINOMETRA PULCHELLA, Pourtales, sp. the ventral branches of the axial cord (a’)' which extend into the perisome at the side of the food-groove, . oe eS 1 This is wrongly lettered ad. Page 98 98 97 98 The Voyage of H.M.S.” Challenger.” Crinoidea. Pl. LX. P.H.C. dir. Geo West & Sons del. lith.et imp I. ACTINOMETRA PULCHELLA, Pourt., sp. 2. ANTEDON CARINATA, Leach, Sp. 3—6. ANTEDON ESCHRICHTI, Mill, sp Tiel aes ‘ j frp a ol weit hd) ihe ) AY eeonitn ire ee ee Fig. 6. PLATE LXI. Fig. 1. ACTINOMETRA PULCHELLA, Pourtaleés, sp. . Vertical longitudinal section of an isolated disk. The section passes through the edge of the mouth, which is seen just in front of the large anal tube. The lobular structure in the centre of the lower part of the disk beneath the fore- gut is the plexiform gland, Figs. 2-5. AcTINOMETRA PARVICIRRA, Miill., sp. . Vertical longitudinal section of the calyx and disk. The situa- tion of the chambered organ between the centro-dorsal and radials is well shown ; as are also the marginal position of the mouth and the numerous coils of the digestive tube, from some of which the epithelial wall has fallen away. The labial plexus is relatively large in the upper lip (i.e., behind the mouth), but is inconspicuous in front of it, . Transverse section of an ungrooved or non-tentaculiferous arm, close to the base of a pinnule. ‘The ventral surface is flat, without any food-groove or tentacular apparatus, and owing to the backward extensions of the ovaries below their points of attachment to the genital cord, one appears in section upon each side of the middle line (p. 110), . The upper part of a transverse section of a normal tentaculi- ferous arm at the articulation of two joints, showing the connection of the ovary and genital cord. In the coeliac canal is a section of a parasitic worm, . Transverse section of the lower part of an arm just beyond the attachment of a pinnule. On the left side are seen three funnel-shaped water-pores, the inner ends of which lead into the genital canal containing the triradiate genital cord, Fig. 6. ACTINOMETRA NIGRA, r. sp. ‘Transverse section of an arm through the middle of a joint, showing the branches of its axial cord. The genital canal is occupied by a relatively large genital cord, and the racial blood-vessel is well shown beneath the middle line of the food-groove, between the ambulacral epithelium and the water-vessel, _ Diam. 10 af 20 27 30 Page 103 103 113 133 96 121 HE VoYAGE OF H.M.S. ** CHALLENGER.” CRINOIDEA. PL. LX]. P.H.C. DiR. 1. ACTINOMETRA PULCHELLA, Pourrt., SP 2-5. ACTINOMETRA PARVICIRRA, MULL., SP 6. ACTINOMETRA NIGRA, SP.N PLATE LXIL. PLATE LXII. Explanation of the Letters. A. Axial cord of the ray. Z. Basiradial ligament. a’. Its branches in the dorsal skeleton. id. Dorsal ligament between the ray-joints. ad. Its upward extensions into the plated perisome of “i. Interarticular ligament. the ventral side. lp. Labial plexus. ae. Ambulacral epithelium. M. Mouth. ai. Primary interradial cords. m. Muscle. . Anambulacral plate. Basal. . Radial blood-vessel. c. The bands of more or less calcified connective tissue in | the body-cavity. . Fibrillar sheath round the vascular axis of the stem. . Interradial portion of the circular commissure. . Ambulacral nerve. . Its oral ring. . Oral blood-vascular ring. . First and third radials. . Rectum. . Plug of calcareous tissue within the radial funnel. . Spinelets on the anambulacral plates. ch. Cavities of the chambered organ. ste. Subtentacular canal. ch’. Their downward prolongations into the stem. sub, Subambulacral plate. chn. The nodal enlargements of these peripheral vessels. sy. Syzygy. ev. Cirrus-vessel. V. Central vascular axis of stem. D,, Ds. Second and fifth distichals. W. Radial water-vessel. Sg. Fore-gut. wp. Water-pore. G, Gut. wr. Water-vascular ring. g. Its epithelial lining. wt. Water-tube. gv. Genital vessel. a. Plexiform gland. Intervisceral blood-vessel. Its ventral end which joins the labial plexus Explanation of the Colours. Black—The nervous system, both ambulacral and antambulacral. Green—The water-vascular system. Red-—The blood-vascular system and the plexiform gland. Diagrammatic longitudinal section of a Pentacrinus decorus. On the right side of the figure the section cuts the anal tube, and on the left side it passes along a ray and the base of an arm. se Voyage of H.M.S Challenger” Crinoidea .Pl. LXil. : wt Za, “tines mn ‘ AOR MTSE caren CPOE Us aS eee PHC. dir Mintern Bros amp PENTACRINUS DECORUS ,Wyville Thomson u & Highley del et lith AIT AA | Mt Hh | | Wil 3 9088 00722 8844