[cmoirs of % fjjuseunt of Comparatifa Zoology AT HARVARD COLLEGE. Vol. XXV. No. 2. CLEIOCRINUS BY FRANK SPRINGEE. WITH ONE PLATE. -CAMBRIDGE, U.S.A.: Printed for tijc JWuseum. January, 1905. VfiA With the compliments of Comparative £00(00,11 Frank Springer. college. Vegas, New Mexico. No. 2. CLEIOCRINUS. BY FRA2ntK springer. WITH ONE PLATE. CAMBRIDGE, U.S.A.: Printed for tije fHuscum. January, 1905. CLEIOCRINUS. The genus Cleiocrinns was established by the eminent Canadian palaeon- tologist, E. Billings, in 1856,* to receive certain very peculiar Crinoids found in the Trenton Group of the Lower Silurian, at Ottawa, Canada. It was based upon one species, C. regius, which he described at the same time (he. cit., p. 277). In 1859 he published,! along with the generic diagnosis, a full description, with good figures, of C. regius, the only species in which the calyx was then known, and named two other species, C. grandis and C. magnificus, upon fragments of the column ; — the main apparent distinction of these being their larger size, and in C. magnificus the less relative thickness of the column joints. The genus has been a puzzle to Crinologists ever since, — both as to its actual structure and its systematic position. Its lowest ring of plates, described by Billings as resting on the column, consisted of ten plates, — five radially situate and five interradially, — which was so fundamentally different from the calyx plan of all other known Crinoids that it was impossible to assign a place for it without introducing hypothetical plates within the proximal ring of Billings, concealed by the column. Inter- pretations of the calyx based upon theories of this kind were none of them satisfactory, and left the position and relations of the genus in much doubt: The stratigraphic position of Cleiocrinns renders it a form of special interest, because it is one of the earliest of known Crinoids. It is asso- ciated with Blasioidoerinus, Palceocrinus, Hyboerinus, Carabocrinus, and other primitive forms, in an epoch when the Cystids were the prevailing Echi- noderm type. The Trenton Limestone is one of the oldest formations in which Crinoids have been found. It is considered to be approximately * Report Geological Survey of Canada, 1856, p. 276. f Figures and Descriptions of Canadian Organic Remains, Dec. IV., pp. 52-5-1. PI. V. 94 CLEIOCRINUS. equivalent to the Middle Bala of England, and to Stage d 4 of Barrande's section of the Ordovician of Bohemia. I have recently had the opportunity, thanks to the favor of Dr. J. F. Whiteaves, to examine all the material of the genus belonging to the Geological Survey of Canada, with results of such extraordinary interest as to warrant a special account of it, in advance of the Memoir as to which my investigations were more especially directed. HISTORY OF THE GENUS. Billings's account of the genus, as given in Decade IV., p. 52, is as follows : — " Generic characters. — Cup, large, conical or pyriform ; basal plates, five; rays, five, alternating with the basal plates; the third plate of each ray is pentagonal and bears two secondary rays, which are several times divided above. Between two of the rays a single vertical series of azygos interradial plates extends from the base to the margin of the cup. The azygos plates and rays are all firmly anchylosed together by their lateral margins up to the height of the fifth or sixth sub-division. The column is pentagonal or nearly round. "This genus has the structure of a Pentaerinus, with numerously divided arms all soldered together in the walls of the cup." Von Zittel in 1879 * referred the genus to the family Crotalocrinidoa. In the same year Wachsmuth and Springer! referred it to the Ichthy- ocrinidse, and discussed it as follows : — " The generic description was made from a single specimen, and this was in several respects defective. Cleiocrinus has, according to Billings, five basals alternating with the radials, and forming with them a belt around the column. Such a structure has never been found in any Crinoid. In the typical specimen, the comparatively large column conceals from view the lower part of the calyx, a space large enough to accommodate one or two series of plates, and analogy suggests that this may have been the case. The five plates which Billings found alternating with the primary radials. and which he called basals, are certainly interradials ; and as the specimen in every visible character closely resembles IcHhyocrinus and * Eandb. der Pal., I., p. 357. f Revision of the Palseocrinoidea, Pt. I., pp. 35-36. CLEIOCEINUS. 95 allied forms, we have good reason to suppose that it, like those forms, possessed five small basals and three underbasals, both hidden by the column. The latter were probably very minute and rudimentary, since the specimen is from the • Lower Silurian, where it is almost the only representative of the family. This alone induces us to try to define generic characters from a single imperfect specimen. Notwithstanding, therefore, that some of the elements are problematic, we propose until something better is found, the following: — " Raised generic description. — " Then follows a generic diagnosis based upon the probable presence of three minute or rudimentary underbasals and five basals, all hidden by the column. In 1886 * the genus was further discussed by us, and a diagrammatic figure from the type specimen, made by Mr. Walter R. Billings, was given (Op. cit., PI. IX., Fig. 5), in which the hypothetical five basals and three infrabasals were indicated by dotted lines — thus giving the basal structure of the Ichthyocrinidae generally. A further revised generic diagnosis was added, which did not differ greatly from the former one, — the chief new point being that the anal plates, instead of being four or five in number, extend the full length of the calyx; and that the arms are "apparently recumbent." It was also stated, on information furnished by W. R. Billings, that " the ridges of the column are interradial in position, which confirms the supposition made by us (Part I, p. 36), that Gleiocrinus possesses underbasals, and that the so-called basals of E. Billings are interradials. He also states that the lowest visible circlet of plates ' apparently overlaps the column, instead of passing under it,' which shows that the base must have been concave, with ample space for the basals and underbasals to lie concealed from view." We further stated : " If certain parts were better known, we should make it the type of a new family, but at present, having no positive knowledge of the basal regions, nor even of the arms, we are not in a position to give a satisfactory definition of the group." Although E. Billings had said, in his description of C. regius, that it had "about forty . . . tentaculated, free rays," it was not understood that this meant pinnulate arms until after the last mentioned discussion, when W. R. Billings sent to Dr. Wachsmuth a drawing from another specimen of that * Revision, Pt. III., See. 2, pp. 152-3. 96 CLEIOCRINUS. species, showing that the arms are fringed with closely packed pinnules. This pinnulate structure, if it had been appreciated at the time, would have presented a very serious obstacle to the inference of the genus to the Ichthyocrinidse, in which entire group pinnules were thought to be wanting. Von Zittel, in his Grundziige der Palaeontologie, 1895, does not seem to find any place for the genus ; nor does Eastman, in his annotated translation of the work in 1900. Bather, in Ray Lankester's Treatise on Zoology, Part III., p. 191, places the genus provisionally among the Flexibilia Impinnata, and gives the fol- lowing diagnosis of its characters : " IBB and BB hidden by stem ; BR small and separated by a large pentagonal interradial ; arms isotomous to about VIIBr, and all appear to interlock and to be joined by close suture ; post. IR supports a vertical series of anals, which reach the full length of the arms." DESCRIPTION OF THE SPECIMENS. It having become necessary for me, in connection with a general investi- gation of the group Flexibilia, to determine more definitely, if possible, the systematic relations of this perplexing genus, I applied to Dr. J. F. Whiteaves, Assistant Director of the Geological Survey of Canada, for the loan of the specimens of Cleiocrimis in the Museum of the Survey at Ottawa. With the most obliging courtesy this material was placed at my disposal, and was promptly packed and shipped to me by Dr. II. Ami, Curator of the Museum, with valuable notes giving detailed information as to the history of each specimen. I find it difficult to adequately express my sense of obligation to both these gentlemen for the cordial interest which they manifested, and their careful attention to my wishes : and I desire to here record my pro- found appreciation of the opportunity, for which I am indebted to them, of an intelligent investigation of these unique fossils. The specimens reached me safely at Burlington in November, 1903. They were found to consist of all of Billings's types figured upon Plate V. of Decade IV., except 2a, and some important additional material since acquired by the Canadian Survey. The latter included a crown of very large size, but poorly preserved, and a stem thirty inches long with the root attached that may belong to it ; also a fragment about seven inches long of a still larger stem over one inch in diameter where not flattened. With the origi- CLEIOCRIXUS. 97 nal specimens found by E. Billings there is also the crown which belongs to the fragment figured by him as lc, which is very important, as it shows most beautifully the real character of the arm structure. As these specimens call for extended study and discussion, I will, to avoid frequent repetition, designate them as follows: A. C. regius. Billings's principal type specimen, — original of Figs, la and 16 of Plate V., Decade IV. A splendid specimen, much flattened above the base, but otherwise beautifully preserved, with calyx com- plete and perfectly exposed on both sides, and having small portions of the column and arm bases attached. Billings's figure \b). C. The remainder of the crown belonging to specimen B, not figured by Billings. Upper part of calyx and portion of arms and pinnules; — greatly flattened, but very perfectly preserved on one side. The fractured edge adjoining B is not quite perfect, some small pieces being broken off (PI. I., Fig. 3a). D. Several pieces of column, nearly continuous from B, with terminal root, the original of Billings's fig. lg. Two of these are figured herein, PL I., Figs. 3c and od, and the root, Fig. 3c. Specimens B, C and D are parts of the same individual, which fit together very well, except at the junction of B and C, where the edges of some plates are somewhat frayed by accident in col- lecting ; and between 3d and 3c, where a piece is wanting. The basal portion of the cabyx, 'being of very firm and rigid construc- tion, was only slightly affected by pressure; but above, being flexible and composed of thin plates, it was flattened out, so as to become quite fragile in the fossil condition, resulting in the frac- ture and loss of parts of some plates when exposed in the quarry where it was found. E. C. magnificus. A very large crown, consisting of the calyx, with a very small portion of the stem, and the bases of part of the arms. The surface of this specimen is very soft and friable, and it is considera- bly injured. The preservation is quite different from that of those 98 CLEIOCKINUS. above mentioned, which evidently occurred in a fine grained shale, softer than the included fossils ; while in this the enclosing matrix is harder, and not readily removable without carrying the surface of the fossil with it (PL I., Fig. 11). F. A large stem, thirty inches long, with the root attached. It was found in the same quarry with specimen E, and there is good reason to be- lieve belonged to it; but a portion of the stem at the proximal end is missing, probably amounting to five or six inches. G. Part of another still larger stem, similar to F (PI. I., Fig. 12). STRUCTURE OF CALYX AND ARMS. THE ARMS AND PINNULES. The first observation of these specimens made clear the fact that the arms are pinnuliferous, — a fact which has been overlooked in the discussions here- tofore ; although, as already stated, Billings, in his description of C. regius, Dec. IV., p. 56, mentions the presence of " tentaculated, free rays." The structure of the arms is perfectly shown by specimen C (PI. I., Fig. 3 a). They are direct continuations of ridges which follow the brachial series in the calyx, beginning at about the first bifurcation with faint linear elevations, and gradually enlarging until they pass into the free arms. These are quite angular on the back, simple, uniserial, composed of short, wedge-form plates, each of which gives off a pinnule from the longer end. The pinnules are slender, and lie close together (PL I., Fig. 10). At somewhat irregular distances below where the arms become free, at the outer margins of the rays, there are given off subordinate branches, which originate on a bifurcating plate and lie closely alongside the outer arms of the ray, the plates of the two abutting and interlocking. These subordinate branches are the proximal portions of fixed pinnules, which are incorpo- rated in the calyx walls, and apparently become free between the arm bases, though they are concealed from view by the regular pinnules. In other interbrachial spaces higher up, from the last IIIBr or IVBr, and mostly on the outside of the dighotom, similar pinnules are given off, but not with entire regularity (PI. I., Fig. 8). All these are closely joined together and to the adjacent arms, and incorporated into the calyx walls, until they reach the upper margin and become free. The arms are quite clearly shown in Billings's type specimen (PL I., Figs. 1, 2), where the bases for a distance of several brachials are in some places well preserved, having the pinnules attached, — though neither of them is as well shown as in specimen C. 100 CLEIOCRINUS. THE CALYX. The calyx plates are all closely abutting, — the suture lines, both between successive brachials and between those of adjoining series, being marked by small pits, or crenulations, indicating a union by a sort of articulation, or loose suture, such as we see in specimens of Forbesiocrinus. In this respect the structure is decidedly like that of the Ichthyocrinidae. There is a com- plete absence of any interbrachial system, except at the anal side, where a vertical series of plates, originating on the posterior basal, rises high up between the arms, though not quite to the margin of the cup. The main general characteristic of this calyx is the manner in which the ray divisions are joined to each other by lateral union of their plates with those of their fellows, and with the plates of the anal series. Billings fully appreciated this when in his generic description he noted as a feature of the structure of the genus its " numerously divided arms all soldered together in the walls of the cup." The plates are comparatively thin, and the mode of union between them imparts a marked degree of flexibility, — more, apparently, than in IcMhyoennus. None of the specimens disclose any portion of the disk, but it is evi- dent, from the manner in which they are flattened, that it was very thin and pliable. Of the mouth and anal opening we know absolutely nothing. The arms, the manner in which the radial ridges lead to them, and the structure and arrangement of the fixed pinnules, are very much like those of Glyptocrinus and Rdeocrims ; but the interbrachial system of those genera is entirely wanting, — there being no supplementary plates, except at the anal side, whose vertical series bears some resemblance to theirs. The manner of compression of the calyx would indicate a disk structure more like that of Reteocrinus o' neatti and the Ichthyocrinidae. THE BASE. Examination of the specimens as they were received did not seem to throw any new light upon the nature of the base. The column in specimen B is obtusely pentagonal, — the exterior angles being interradial, which pro- claims a dicyclic base (PI. I., Fig. 3 b). The axial canal in this specimen, at about one inch from the base, is also pentagonal, and its angles coincide with those of the exterior of the column (PI. I., Fig. 3/); which is a de- parture from the rule of alternation, and forms another minor exception to CLEIOCRINUS. 101 the law of Wachsmuth and Springer, similar to that of Glyptocrinus fornshetti, — a monocyclic species in which both stem and canal are radial, and which is also from the Lower Silurian, among the earliest Crinoids. Granting that there is a dicyclic base, the question remained, what is the exact nature of it ; and what are the five plates lying between the radials '.' Billings, with singular sagacity, called them the "true basals." His state- ment, in the description of C. regius (Dec. IV., p. 53), is as follows : "At first sight there appear to be ten small basal plates, but upon examination five of these are found to be the first plates of the five rays which rest im- mediately upon the upper joint of the column ; the other five are the true basal plates." Wachsmuth and Springer, having classed the genus with the Ichthyocrinidte on account of the strong resemblance of its pliant calyx to that of Icldhi/ocrinus, had supposed that it might possess the basal arrange- ment of the group, viz., 5 basals and 3 infrabasals, both hidden by the column ; and they considered the pentagonal plates between the radials to be interradials. Since it now appeared that the genus is pinnulate, with an arm structure which differentiates it absolutely from all the known Pala?o- zoic Flexibilia, there seemed to me equally good reason to infer the presence of five infrabasals, as in the base of the dicyclic Camerata. The superficial aspect of the specimens furnished no information on this point ; and the only important fact gathered from the first examination of them was, as had been pointed out by W. R. Billings in a letter, that the proximal plates of the calyx do not rest immediately upon the upper joint of the column, as stated by E. Billings, but they seem to overlap the column, and form a ring around its upper edge. The two specimens of C. regius both showed this very plainly ; and they also showed the further curious fact that the five radially situate plates of this proximal ring, although having nothing to rest upon or to support them from below, at least exteriorly, are distinctly angular below. It was apparent, however, that no further information was to be obtained, unless we could find some means of seeing what is underneath the column. My examination of the specimens gave no hope of being able to detach the column in either of them ; but after a very careful study of specimen B, under a strong magnifier, I came to the conclusion that it might be possible to get at the inside of the base by removing a part of the plates above it. This specimen preserved the first two rings of plates nearly in situ ; it was slightly flattened by pressure, and on the side opposite that shown in Bil- 102 CLEIOCEIXUS. lings's Fig. 1 c the upper ring and some plates from the next ring above it were crushed in over the basal cavity, and cemented with a very fine, shaley matrix. If these could be removed, without destroj-ing the rest, we might see what lies next to the column. The small size of the specimen, and the uncertainty as to how the fractures might run, rendered .the opera- tion a delicate and risky one to undertake with a type specimen ; but I thought the benefit to be gained in case of success would warrant the risk. I accordingly laid the matter fully before Dr. Whiteaves, and requested his authority to undertake it. This he gave without hesitation, and in the most liberal manner, leaving me free to act with the specimen as if it were my own. I wish here to express not only my grateful acknowledgment for the personal confidence reposed in my judgment in so delicate a matter, but also, in view of the important result attained, my thanks as a palaaontologist to Dr. Whiteaves for the benefit he has conferred upon science, by furnish- ing the means of information which, in my opinion, there was no hope of obtaining in any other way. I give this opinion, not only on account of the rarity of the specimens, but of their poor preservation. In all others that I have ever seen the calcareous test is soft and friable, and the sur- rounding matrix adheres to it so closely that any kind of fine cleaning is impracticable. The work of removing the necessary plates and debris from above the base of the specimen was tedious and difficult, being performed entirely under a ten-power dissecting microscope, with tools specially fashioned out of needles and fine steel pens. It was completely successful, however, without any mishap, and disclosed a structure most extraordinary and anomalous, unlike any of the previous suppositions, and wholly at variance with that of any other known Crinoid. Instead of two, there is only one ring of plates inside of the proximal ring of so-called radials and interradials, which are seen on the outside and surrounding the column. The axial canal is very large, and obscurely pen- tagonal ; and around it, resting on the column and occupying its full thick- ness, are five large, strong, quadrangular plates, sloping from within upward to a thin upper face, radial]?/ situate, which are followed by the first and second primibrachs, not alternating with them but in direct succession, without the interposition of other plates. The first plate visible externally in the radial series is not, as a rule, visible at all from the interior when all CLEIOCRINUS. 103 plates are in place ; but it, as well as the interradially situate plates, is out- side of the lower ring and outside of the column, projecting downward for a distance of one to four columnars. Thus the ten plates forming the proximal ring exteriorly, do not, except as to the upper angular points of four interradials and one radial, enter into the interior of the calyx wall proper, but are suspended on the outside of it. They appear out of place, as if they might have accidentally slipped clown around the column. They are rather thin, and are firmly grown to the outside of the true proximal ring of plates, the angular points of four of the interradials and of the right posterior radial rising slightly above their level. The first primibrachs are exteriorly flush with the plates of the lower outer circlet, and rest upon them, being sloped at the lower corners so as to fit the angles formed by the upper points of the interradials, which are thus visible from the in- terior. These first primibrachs also lie" directly above, but do not rest upon, the plates of the inner circlet, not alternating with them but in direct succession. The successive plates are all radial in position, without any alternation whatever. Thus the five radially situate plates which rest upon the column lie within the ten plates of the outer circlet, and meet them, not by their upper or distal edges, but by their outer, or dorsal, surfaces. Now for the evidence of this : Referring to Plate I., Fig. 3 b shows the specimen B from the right posterior side, with the lower circlet of radial and interradial plates as seen from the exterior, and the first primibrachs resting upon them and flush with them. The same thing can be seen in Figs. 1 and 2, showing the two sides of the perfect calyx (Billings's 1 a and c). Fig. 5a is from a photograph — enlarged two diameters by the camera, and retouched with the brush — of the opposite, or left lateral, side of speci- men B, after removal of the plates and debris covering the basal cavity, — an obliquely interior view. All five of the large proximal, radially situate plates are in plain view, with the large axial canal in the middle. Two primibrachs and part of a third are in situ — in direct succession with the last mentioned plates — and, at the right, the first plate of the anal series, slightly displaced, resting upon the posterior interradial. Two of the radial plates of the outer circlet are visible, one in the middle and one to the right, with one of the interradial plates between them. The interradial to the left has been removed, leaving the exterior face of the inner proximal plate exposed, just as it rests upon the column. On the opposite side the upper points of two of the interradials can be seen, between the lower 104 CLEIOCEIXUS. corners of the primibrachs, and toward the right, the corner of the right posterior radial, which differs slightly in shape from the other radials. In this figure the relative thinness of the plates of the outer circlet can be readily seen. Fig. 5 b is a more nearly side view of the same structure, enlarged four diameters. Here the angular lower edge of the radial of the outer circlet can be well seen, and the drawing shows very clearly the way in which these plates hang suspended to the outside of the inner ones, and project downward over the column without anything for their angles to meet or rest upon. In both the last figures there appears a depression at the middle of the upper edge of some of the inner plates. This is actually a shallow, lip-like groove, plainly visible on three of the plates, apparently traversing the inner surface of these plates in a radial direction. I cannot trace it upon the surface of the succeeding primibrachs which are preserved, but the inner surface of these plates is somewhat ob- scure, and did not come out freely in cleaning. If this groove be taken as showing the position of the axial nerve cord leading into the column, it would seem to indicate that the axial canal occupies morphologically its proper radial position in the calyx, notwithstanding its interradial cross- section below the calyx. Fig. 6 is an attempt to show by a diagram of a vertical cross-section, the relative position of the plates of the inner and outer circlets, and of the primibrachs succeeding them, and also how the outer plates project downward over the column. These illustrations will give a good idea of the structure as I interpret it from the most careful study of the specimen which it was possible to make. It will be seen from them how large and strong these inner plates are. They form a rigid ring surmounting the column, of much stronger construction than the succeeding calyx plates ; and as a result of this the base, reinforced by the outer circlet also, usually retains its shape, while the calyx above is greatly flattened by pressure. Now this sort of a base is absolutely anomalous, and without precedent anywhere. The five inner plates resting upon the column, being radial in position, must be taken to be the infrabasals. But what has become of the basals ? It is plain to me that they are the so-called interradials, which, by some strange freak of nature, have morphologically — not accidentally- become displaced from their proper position in the calyx wall, being pushed in between the radials, and both having slipped down over the infrabasals. Or, supposing a reverse process to have taken place, we may consider that CLEIOCEINUS. 105 the disturbance came from below, the base being thrust upward into the calyx, expanding it until the radials were separated, the basals forced in between them, and the infrabasals into a ring formed of the two. It will be remembered also that the radials are angular below, although with nothing whatever in their present position to meet their angles, or for them to rest upon. The basals, on the other hand, are angular above, so that the inferior angular faces of the radials would fit between the sloping upper faces of the basals if they were brought together. If, therefore, with this idea in view, we could stretch the Crinoid up from the column, so as to make room for these two circlets of plates within the calyx wall, we should find that they would fall into their relative positions without any difficulty. This imaginary process may be indicated by the accompanying diagrams, in which the plates in question are represented by dotted lines, — Fig. 1 as they are now, and Fig. 2 as they would appear if placed in their proper position. IE XJB^ V 1Br' ) Fig. 1. Fig. 2. This seems to me a reasonable explanation of the relation of these struc- tures so anomalous, — although I do not find myself able to account for it upon any teleological or evolutionary basis. I must look for enlightenment on this phase of the subject to some of my transatlantic friends, who have been admitted much farther into the mysteries of Phylogenesis than I. The structure looks like one of those experiments which we sometimes encounter in Nature, and recalls the observation of Diderot in his " Pensees de lTnter- pretation de la Nature," where he says : " It seems that Nature has taken pleasure in varying the same mechanism in a thousand different ways. She never abandons any class of her creations before she has multiplied the indi- viduals of it in as many different forms as possible." At all events the ex- periment was a short-lived one, for it is never heard of again. It must be 106 CLEIOCRINUS. remembered that this Crinoid occurs in the lowest part of the Ordovician, or Lower Silurian, contemporaneous with the Cystids; and it may well be that it represents the end of some line of evolution in which the alternate succes- sive arrangement of the skeletal elements has not yet been fully established, — a consideration which may also be borne in mind in connection with the abnormal orientation of the axial canal. But the fact that these plates of the exterior circlet, hanging to the outside of the calyx as it were without visible office, should have just the angular faces to enable them to fit into their proper places in the normal succession, seems to me most wonderful. Yet this case may not, after all, be much more anomalous than the con- verse one of the Upper Silurian genus Calpiocrinus, where the infrabasals, in- stead of being within the circlet of basals, have overgrown them to such an extent as to completely envelop and conceal, not only the basals, but even sometimes the radials also. SYSTEMATIC RELATIONS OF CLEIOCRINUS. The prime fact suggested by these observations on the actual specimens is that Cleiocrinus is evidently an intermediate form between the Camerata and the Flexibilia, of a most interesting character. So far as the calyx is concerned, the general habitus of the specimens is that of an Ichthyocrinus ; its articulate structure and flexible calyx point strongly toward the Flexibilia. On the other hand, the presence of pinnules, and of five infrabasals instead of three, differentiate it absolutely from the known Flexibilia Impinnata, to which all palaeozoic forms of the group hitherto known belong. The bra- chial structure — the form and arrangement of the arms and pinnules, with ridges following the radial lines and running into the arms — is, as already suggested, essentially that of Gb/jitocrinus or Reteocrinus. The superficial resemblance, in this respect, is perhaps greater toward such a form as Glyp- tocrinus dyeri (PI. L, Fig. 13), but structurally the analogy is much closer with Reteocrinus ; — although I do not mean to be understood as claiming that the two are actually at all closely related. If we eliminate the interbrachial system from Reteocrinus, all except the anals, we shall have substantially the calyx of Cleiocrinus. The dicyclic base with five infrabasals, the longitudinal series of anal plates extending almost to the margin of the disk, and the incorporation of pinnules within the calyx CLEIOCRINUS. 107 walls, are characters common to both. Of course the fixation of pinnules is accomplished in different ways, being in Reteocrinus by means of supplement- ary plates, while in Cleiocrinus it is simply by lateral union of brachials and pinnules. Aside from the great strengthening of the radial and anal series. the calyx of Reteocrinus is not so very much unlike that of Cleiocrinus. It is built up of a large number of thin plates, evidently forming a pliant wall be- tween the rays. Its calyx was clearly pliant, and the disk conspicuously so. I have more than a hundred specimens of R. onealli which were preserved in a very fine, soft, calcareous mud, and in almost every case the calyx is flattened, and the disk more or less bulging in a variety of shapes, as if it were extremely flexible. It is really a thin integument of very small plates, without definite arrangement. I am unable, however, after close examina- tion of a large series of well preserved disks, to find any trace of ambulacral furrows upon the surface, nor of any opening for the mouth. The anal open- ing is clearly indicated in some cases ; it is not conspicuous, and evidently was often entirely closed, or concealed by the contraction or folding of the in tegument. I have figured a number of excellent specimens of this species, for com- parison on these several points (PI. I., Figs. 14 to 21). A careful study of a large number of these specimens, in unusually good preservation, leaves no reason to doubt the correctness of the assignment of the group to which they belong to the Camerata. The mouth and ambulacra are undoubtedly sub- tegminal. But it seems to me that they, with the addition now of Cleiocri- nus, lie in the borderland closely approximating the Flexibilia, and should be considered as intermediate forms. This would accord with the opinion fre- quently expressed in private correspondence by P. II. Carpenter, who was much impressed by the strong resemblance of the Reteocrinida? to the Ichthyocrinidaj. 108 CLEIOCKINUS. DEFINITION OF THE GENUS. The facts herein brought out necessitate a new definition of the genus, which I propose as follows : — Cleiocrinus Billings. Generic Diagnosis, amended. — Calyx large, conical, or pyriform ; pliant ; plates joined by loose suture. Base dicyclic ; infrabasals five, invisible ex- teriorly. Basals and radials not in normal succession, but alternating with each other in a horizontal ring of ten plates surrounding the infrabasals and projecting downward over the column. No interbrachials, except at the anal side ; anals in vertical series, resting on truncate posterior basal, and ex- tending high up between the rays. Bays and their divisions up to the free arms contiguous and interlocking ; brachials bifurcating several times in the calyx, giving oft' fixed pinnules, which are incorporated by lateral union with adjacent brachials and become free between the arm bases. Arms simple, uniserial, and pinnulate. Column obtusely pentagonal, or nearly round. SPECIES. Billings described three species of this genus : — C. regius from the calyx, and ('. grandis and C. magnificus from stem fragments only. I see nothing to indicate any substantial distinction between the stems of C. regius and C. grandis, — both being pentagonal, and the difference in size not being very great. The stem fragment which he named C. magnificui (Dec. IV., PI. V., Fig. 3) is round, with proportionally much thinner columnars, and of very large size. It is probably from the lower part of the stem, where it seems to lose its angularity and become round. In the new material there is another fragment, still larger, being over an inch in diameter, which is also round ; the uncrushed part of it is figured on Plate I., Fig. 12. The large crown E. (PI. I., Fig. 11), and the long stem already mentioned — thirty inches long — came from the same quarry, and may x CLEIOCKINL'S. 109 belong together. This stem is similar to the two last mentioned fragments, and it, together with the crown E., may well be taken as an example of C. magnificiis, of which no portion of the calyx has been seen before. If so, it is no doubt a good species, and represents a mature development of the type of C. regius. The preservation of the calyx is so poor that not much can be made of it beyond its general appearance. The proximal series of plates at the base are not well defined, but the arm bases are visible for a sufficient distance around to show that it had at least one hundred free arms. As it lies flattened, the top of the calyx at the arm bases is fully five inches in width, and when in its natural form it must have been nearly four inches in diameter, — one of the largest and most magnificent stalked Crinoids known. The stem as preserved is thirty inches long, and was probably six inches longer; it is five eighths of an inch in diameter at the upper end, and seven eighths at the root; very slightly pentagonal above, and round below. It is composed of very thin columnars, much thinner than that of C. regius, there being about sixty to an inch generally, and probably more near the distal end. The axial canal at the upper end is obscurely pentagonal. The stem terminates in a root similar to that of C. regius. The other two crowns are very much alike. Specimen B-C (PI. I., Figs. 3 a, b) is the smaller of the two, and doubtless represents a younger stage. It has but six arms to the ray, so far as can be observed, or about thirty in all ; whereas specimen A has eight arms in most of the rays, or about forty in all. If we had other specimens showing a constant differ- ence in this respect, this might be ground for specific separation. But it seems very probable that, as is often the case, there is considerable vari- ability in the number of arms, which is, indeed, indicated in specimen A, where one ray has only seven arms. It is a fact well established by ob- servation, but persistently ignored by some describers of species, that the number of arms in Crinoids may be a good specific character in some groups, and entirely worthless in others. These two specimens have about the same form and proportions, being elongate conical and slender, whereas specimen E, with its enormous development of arms, although similarly flattened by pressure, is robust and greatly expanded, so that it is proportionate])* much lower and wider. Specimen B-C, therefore may be taken as another rep- resentative of C. regius. The two known species may accordingly be defined as follows : — 110 CLEIOCRUSTUS. Cleiocrinus regius Billings. Calyx elongate conical, gradually expanding from the base to near the top, where it is slightly contracted ; plates flat and without ornamen- tation, except longitudinal ridges following the brachial series into the arms. Infrabasals large and strong, invisible exteriorly; standing ver- tically upon the edge of the column, widest and thinnest above, succeeded directly by the first primibrachs; they have a shallow groove at the middle of the upper edge. Basals pentagonal, truncate below and angular above, except the posterior one, which is quadrangular, with perhaps a slight sloping at one corner; they lie between the radials, forming with them a horizontal ring of ten plates, which envelop the infrabasals by their dorsal surfaces and conceal them from view ; they also project downward over the column for a short distance, without support at the lower margins of the plates. Radials alternating horizontally with the basals, pentagonal, with the angular face below, and much smaller than the succeeding brachials. Anals in a single vertical series, interlocking with adjacent brachials, and extending well up toward the arm bases. Primibrachs two, increasing in width upward ; the first one sloped at the lower corners and widening rapidly upward ; the axillary primibrach followed by two to three bifurcations, giving six to eight arms to the ray, or thirty to forty in all. The ray divisions are marked by a narrow, longitudinal rid