Io8 SMITHSONIAN INSTITUTION 



6. The general prevalence of regularly spaced syzygies. 



7. The constant presence of pinnules ; the first two segments of which are always differ- 

 entiated from those succeeding. 



8. The general absence of a concave base. 



9. The general presence of a modified top columnal, or proximale. 



10. The general absence of bilateral, and prevalence of pentamerous, symmetry, modified 

 only by tegminal characters and by loss or addition of rays, and not by anal structures in the 

 dorsal cup. 



The type of Crinoidea now constituting the order Flexibilia was not recog- 

 ^nized as the basis for a major group by any author prior to 1877. There is 

 little doubt that if Johannes Midler had been better acquainted with its essen- 

 tial characters he would have perceived its importance in the structure of the 

 crinoids, for in his list of genera in the Abhandlungen, 1843, p. 208, he noted 

 under Poteriocrinus nobilis and P. egertoni that they " belong not to the genus 

 Poteriocrinus." Phillips about the same time, and independently, observed the 

 peculiar habitus of these and allied species, and considered it sufficient ground 

 for the creation of a new genus, for which he proposed in 1841 the preoccupied 

 name, Isocrinus, 1 and in 1843 Taxocrinus. 2 The Austins 3 in 1842, in their 

 proposed Arrangement of the Echinodermata into Families, placed Phillips's 

 genus under the Poteriocrinidae. 



Ouenstedt, in the various editions of his Handbuch der Petrefactenkunde, 

 1852, 1867, and 1885, and also in his Petrefactenkunde Deutschlands, 1874- 

 1876, ranged Taxocrinus, Ichthyocrinus and their allies under the Cyath- 

 ocriniden, or Cyathocrinen. 



Roemer 4 in 1854 included most of the then known genera of this group 

 under his family Cyathocrinidae, disregarding entirely the important work of 

 Phillips, and suppressing his genus Taxocrinus as a synonym of Cyathocrinus. 

 He was the first author to call attention to the tegmen as a character for classi- 

 fication, and he grouped the Stalked crinoids into two sections, which he left 

 without names, as follows: a. Ventral side consisting of a soft skin; b. Ven- 

 tral side covered by solid immovable plates. In the first he placed the Recent 

 and Mesozoic crinoids, plus the Cupressocrinidae and his Cyathocrinidae 

 (which included representatives of all the present Paleozoic orders) ; and in 

 the second the Poteriocrinidae and all the other Paleozoic crinoids. He pro- 

 posed Sagenocrinidae as one of his 21 families for the reception of the single 

 genus, Sagenocrinus, — being the first family name used exclusively for crinoids 

 of this type, although without any perception of its true characters. 



Pictet 5 in 1857 distributed the genera indiscriminately among his three 

 groups, Cyathocriniens, Actinocriniens, and Carpocr'iniens. 



1 Palaeozoic Fossils of Cornwall, pp. 29-30. 



* In Morris, Catalogue of British Fossils, p. 90. 

 "Ann. and Mag. Nat. Hist., vol. 10, pp. 106-110. 



* In Bronn, Lethaea Geognostica, 3d edition, vol. 1, pt. 2, p. 227. 

 e Traite de Palaeontologie, pp. 314-330. 



