30 THE CEmOIDEA CAMEKATA OE NOETH AMERICA. 



2. Pentacrinacea. Calyx with a well defined basal ring ; infrabasals wanting or rudi- 

 mentary. Ambulacral furrows and mouth (in all of them ?) exposed. Tegmen 

 pliable with movable Saumplattchen, or with five large orals and without Saum- 

 plattchen. (Pentacrinidae, Apiocrinidse, Plicatocrinidse, Bourguetocrinidge, Eugenia- 

 crinidee, Holopidse, and Comatulidse.) 



Neumayr's primary divisions are partly based upon incorrect observation. 

 Among the three groups which he refers to the Hypascocrinoidea, the 

 Saumplattchen are subtegminal only in the Haplocrinacea. In the remain- 

 ing groups they may be subtegminal or exposed among species of the 

 same genus. The Ichthyocrinacea even have an open mouth and open 

 food grooves. On the oral question he agreed with Carpenter, and took 

 the six proximals to be representatives of the orals. 



Neumayr ranked the Crinoidea, Blastoidea, and Cystidea as independent 

 classes, and believed that the two former are derived from the Cystidea, 

 which to some extent combined the characters of the three groups. 



Dr. Steinmann^ adopted our classification of 1885, with Palgeocrinoidea 

 and Neocrinoidea as primary groups. 



Two other classifications were proposed in America, — one by Prof. 

 E. J. Chapman, the other by S. A. Miller. The former f is to a large 

 extent hypothetical, being founded upon characters of which nothing, or 

 almost nothing, is known among PalaBozoic Crinoids. His classification is 

 based mainly upon the presence or absence of a canaliculation within the 

 calyx and arm plates for the occupation of axial cords. He recognizes 

 three leading divisions : — 



I. Emedullata. Calyx plates and arm plates without internal canals. 

 II. Fisiulata, Arm plates with dorsal canal. Calyx plates imperforate. 



III. Canaliculata, Calyx plates traversed from the basals upwards by 

 delicate radiating canals. The arm plates canaliferous dorsally. 



The classification of S. A. Miller t may perhaps facilitate elementary 

 studies, but has no value from a morphological point of view. In forming 

 his families he made the number of basals the most important character for 

 division, next the presence or absence of '' subradials," and after this the 

 structure of the ^Sazygous side and other parts." His classification is a 

 reminiscence of that of Angelin, § who divided the Swedish Crinoids into 



* Elemente der Palseontologie, Leipzig, 1888. 



t A Classification of Crinoids, by Professor E. J. Chapman, Toronto, 1882. 

 X American Geologist, Vol. VI., 1890, pp. 275-286, and pp. 340-357. 

 § Iconogr. Crinoid. Suecise, 1878. 



