1888.] NATURAL SCIENCES OF PHILADELPHIA. 357 



calated opposite the second and third radials and an interaxilhwy 

 between the second secondary radials. In Onychocrmus, and those 

 forms of Taxocrinus which resemble it in the expansion of the rays, 

 like T. ivtermedius, there is frequently a large first interradial, suc- 

 ceeded by a variable number of smaller ones ; while in other cases 

 (PI. XVIII, figs. 1 a, b, c) the lower plates themselves are quite 

 irregular,' following the curvature of the rays. They are connected 

 with their fellows in the same interradius by the plates of the disk, 

 which are attached to their inner edges. In both these genera the 

 structure of the posterior interradius resembles that of the recent 

 genus Thaumatocrinus in having a succession of anal plates forming 

 a lateral proboscis-like projection, connected for nioi-e or less of its 

 length with the perisome. Lecanocrinus, Pyaiosaccus, Cyrtldocriniis 

 and Mespilocrinus have an azygous and anal plate, but as a rule no 

 interradials. Lecanocrinus m(( crop eta I us of New' York has no 

 interradial plates ; while a specimen from Sweden, which agrees with 

 the genus otherwise, has at each side one large interradial. Calpio- 

 crinus^ has an azygous plate passing well down between the basals 

 toward the underbasals, and from one to four interradials in the 

 same species. Sagenocrinus^ has a remarkable azygous plate in line 

 with the basals — the sixth parabasal of Angelin — and some varia- 

 bility in the other interradial spaces, although on the whole it is a 

 rather symmetrical form. 



The irregularity in the arrangement of the interradials, so frequent- 

 ly found in this group, their presence between the higher radials, 

 and absence upon the first primary radials in species, and even among 

 individuals of the same species, has always presented to us a difficulty 

 in classifying the Ichthyocrinidae with the Palaeocrinoids. 



^ Calpiocrinus is not tlie aberrant genus which we supposed from Angelin's 

 figures (Rev. I, p. 30, S8). A good series of specimens from Dudley, not other- 

 wise distinguishable from C. fimbiiatus and C.heterodoctylus, — which are probably 

 synonymous — shov\s tliat it has the usual calyx plates of the family — three under- 

 basals and five basals. In a specimen of C. ovatus, the underbasals are concealed 

 by the column, and it is probable that this is the case in most of the Swedish speci- 

 mens, and that in some instances the peculiar azygous plate, in line with the basals 

 has led to a misconception of the latter plates. 



2 Examination ol the specimens leaves little doubt XhzX Sagenocrinush€\ox\g?, 

 to the Ichthyocrinidae. We noted its resemblance to Taxocrinus (Rev. 11, p. 

 202), and it always appeared to us out of place in the family Rhodocrinidae, 

 which is greatly improved by its removal. Our generic diagnosis, made entirely 

 from the figures and insufficient descriptions, is defective and incorrect in some 

 particulars, and will be improved hereafter, as the genus has been discovered in 

 America. 



