282 PROCEEDINGS OF THE ACADEMY OF [1879. 



Family II. CYATHOCRINIDiE. 



The C3 T athocrinidfe represent not only one of the largest but 

 also one of the earliest groups of the Palaeocrinoidea, and they 

 survived every other family of that sub-order. 



J. S. Miller, the author of Poteriocrinus and Cyathocrinus, the 

 two principal genera, placed the former among the Semiarticulata 

 and the latter under the Tnarticulata, which he understood to re- 

 present two distinct families. Poteriocrinus, accoi'ding to his 

 views, had the plates of the calyx articulating imperfectly with 

 each other, while the plates of Cyathocrinus were closely joined 

 by sutures lined with muscular integument. It is unnecessary to 

 examine Miller's divisions in detail, as they are based upon theory 

 and incorrect observation, as is further shown by the fact that un- 

 der the Inarticulata he united Cyathocrinus with Actinocrinus, 

 Rhodocrinus and Platycrinus, which are of course totally dis- 

 tinct. 



Thorn. Austin's classification (1843, Rec. and Foss. Crin.) is 

 equally unsatisfactory. He followed Miller in separating Cyatho- 

 crinus and Poteriocrinus into two distinct families, placing the 

 former among the Platycrinidae, and including therein Caryocri- 

 nus ; and Poteriocrinus with Symbathocrinus amoug the Poterio- 

 crinidae. The former group is based simply upon the presence of 

 but few plates in the calyx. In the Poteriocrinidae, according to 

 Austin, "the lower series of plates surrounding the body, rest on 

 and articulate on the superior columnar joint, which also articu- 

 lates by radiating striae to the concealed dorso-central (basal) 

 plate." By the " concealed dorso-central plate" Austin meant a 

 little tripartite plate, which he and Phillips supposed they had 

 discovered in Poteriocrinus within the ring of the underbasals, 

 but which has been seen by nobody else, and in fact does not 

 exist. The radiating striae, however, are found between the calyx 

 and column, and all along the latter between the joints in all pe- 

 dunculate Crinoids. His disposition of Cyathocrinus is no 

 better, as he arranges it in the same family with Caryocrinus, 

 which is a Cystidean. With our present knowledge it is evident 

 that Austin's divisions are wholly arbitrary, and not accoi'ding 

 to nature. 



The next attempt at classification was made by Prof. Roemer 



