256 PROCEEDINGS OF THE ACADEMY OF 



eal specimen of F. Meeki now before us, the anal space, as may be seen by the 

 figure in the Iovra Report, is entirely vacant, and also without the little row 

 of anal pieces. In five other good examples of this species before us, how- 

 ever, this character is more or less clearly seen. 



From the typical forms of Taxocrinus, Onychdcrinus differs in nearly all the 

 characters distinguishing it from Furbesiocrinus, as well as in having usually 

 as many interradial pieces as the latter. 



As thus separated from b ' orbesiocrinus and Taxocrinus, Onychocrinus still 

 seems to include two types that may yet be found separable, since Forbesio- 

 crinus asfericeformis, Hall, and our species diversus described in this paper, 

 differ from the other species mentioned in having the rays more spreading 

 and free in as far as to the second radial pieces, with arms clustered in little 

 bunches at the extremities of the rays far out from the body ; and the free 

 rays apparently covered above, at least a part of the way out. It is in this 

 type, if we have correctly understood Messrs. Lyon and Casseday, that they 

 found the vault composed of solid calcareous fieces, while in the other species 

 we have mentioned the vault is unknown. 



Such species as our 0. diversus, described in this paper, with their long, 

 spreading, bifurcating rays, and numerous little curled-up arms at their ex- 

 tremities, must, when perfect, have presented much the appearance of dried 

 specimens of the existing genus Astrophytwi ; but we cannot agree with the 

 authors of the genus or subgenus Onychocnmm in the opinion that this type 

 forms a connecting link between the Crinoidea and the Asteroidea,oi that it 

 is more nearly allied to the Star-fishes than other crinoids. 



Onychocrinus diversus, M. & W. 

 Body and rays forming together an irregular five-rayed star, the body being 

 comparatively small, depressed, and distorted by the deeper excavation of the 

 anal side ; while the rays are large, stout, rigid and free, from the second 

 radial pieces outward, and extend out horizontally on the same plane with 

 the base. Basal pieces hidden by the column, or merely shewing as a thiu 

 ring scarcely distinguishable from the last segment of the column, when the 

 latter is attached. Subradial pieces comparatively large ; four of them equal, 

 wider than long, and all pentagonal, with the upper sloping sides longer than 

 the lateral margins ; the fifth one larger (particularly longer) than the others 

 and apparently hexagonal. Radial pieces five to each ray, thick and strong, 

 and after becoming free on the second pieces, curving strongly up on each 

 side of the ray, so as to make the underside of the free rays distinctly rounded ; 

 first radial pieces considerably larger than the subradials, of rather unequal 

 size, wider than long, and heptagonal in form, with probably the exception 

 of one or two of those on the anal side, which appear to be truncated on one 

 side, so as to be hexagonal in outline. Succeeding radials diminishing gra- 

 dually in size, the second and third being wider than long, hexagonal and 

 pentagonal in form, and the fourth transversely oblong, as seen from below ; 

 while the fifth is pentagonal, as seen from beneath, having an obtuse middle 

 angle on the outer side. Beyond this the rays are each composed of a double 

 series of strong pieces, which are slightly disposed to assume an alternating 

 arrangement, the two series continuing in close contact laterally to the fourth 

 pieces beyond the commencement of the double series on the fifth radials, and 

 then diverging abruptly at an angle of 90 to 100, to form distinct rounded 

 branches. At the outer bases of these branches an arm is given off on each 

 side on the third piece from the commencement of the double series, and bi- 

 furcate so as to form a bunch of small armlets ; beyond this the two main 

 divisions of the rays continue on, each composed of a single range of pieces, 

 until the third piece beyond the lateral arms just mentioned, after which 

 they are each composed again of a double series of pieces, on the third of 

 which another arm is thrown off on each side, and bifurcates as before. After 



[July, 



