FOSSIL CRINOIDS. 141 



following "an attempt to sketch the actual race history," which "resulted in 

 the recognition of a distinction between Dendrocrinus and its allies, with their 

 broad radial facets and their tegmen on the one hand; and Cyathocrinus and its 

 allies, with narrower facets and more solid tegmen, on the other." Of the two 

 suborders he says the " Cyathocrinoidea were the first to be specialized and the 

 first to disappear; while the Dendrocrinoidea moved more slowly and went 

 farther, even to our own day." 



In the recognition of two large divisions having these relative periods of 

 development and culmination, we can readily agree; the difference is in the 

 delimitation of the divisions, and the underlying principle upon which it is based, 

 as well as some minor details. Bather's Dendrocrinoidea Distincta include 

 what was in our Poteriocrinidae, with the addition of most of the Dendro- 

 crinites and Botryocrinites, which were included in our Cyathocrinidae. In so 

 including them he necessarily minimizes the importance of the mode of articu- 

 lation upon the radials, which he mentions as one of those characters of which 

 there is "every gradation in the development. . . .articulation of plates (being) 

 developed as need arose." He also definitely rejects pinnulation as a character 

 of any value in these large divisions ; his Dendrocrinoidea Distincta include both 

 pinnulate and non-pinnulate genera, and while his Cyathocrinoidea happen 

 to be all of the latter kind, he says that the presence of pinnules would not 

 remove a genus from that suborder. 



As a minor matter, it may be remarked that, judged by the first of the two 

 characters specified by him as distinguishing the suborders, viz, broad radial 

 facets for Dendrocrinoidea, and narrow facets for Cyathocrinoidea, his name 

 for the former is no more happy than that of the Poteriocrinidae has been thought 

 to be ; for no genus of Crinoids has relatively narrower facets than Dendrocrinus 

 in its typical species, D. longidadylus; and on the other hand no genus has 

 broader facets than Cupressocrinus, which he includes in the narrow-faceted 

 Cyathocrinoidea. 



There is much more to be said in favor of his distinction between the two 

 suborders based upon the character of the tegmen, which certainly represents, in 

 the typical forms, strongly different structures ; yet a close analysis would reveal 

 a considerable amount of gradation in its development; and I am not yet 

 convinced that the mode of articulation, while not so conspicuous, is not a char- 

 acter of broader significance than that, from a phylogenetic standpoint, as well 

 as upon morphological grounds. 



All the genera with round, or narrow, facets, or lacking a transverse ridge — 



