1906] The Species of Botryocrinus. 99 



It should be noted that the holotype is a young specimen, 

 and that, according to Hall, it, or at least the figures of it, "do 

 not fairly represent the species." Therefore the specimens on 

 which Hall based his diagnosis and description should be more 

 important than the specimen figured. Unfortunately they are not 

 to be found in the American Museum of Natural History, and I have 

 had to rely on Hall's description and on the little holotype which 

 Professor H. C. Bumpus most kindly entrusted to me for examin- 

 ation. Its chief measurements are : Height of cup to top of 

 RR, 3.6 mm.; width at base, 1.7 mm.; width at summit, 5 mm. 



Neither the description nor the figures of Hall indicate dis- 

 tinctly that this species is a Botryocrinus ; indeed he himself says 

 that it is "a true Cyathocrinus in structure". Hall, however, as 

 has been previously pointed out (Wachsmuth & Springer, ' Revi- 

 sion' I, p. 82; Bather, 'Brit. Foss, Crin. VIII, Cyathocrinus\ 

 Ann. Mag. Nat. Hist. (6), IX, p. 206 ; 1892), " extended the dia- 

 gnosis of Cyathocrinus to include forms with a small quadrangular 

 radianal". Such a plate is shown in Hall's fig. 7, but in the act- 

 ual specimen it is so obscure that one looks for confirmatory evi- 

 dence. It such a plate were present the posterior and right pos- 

 terior basals would be heptagonal. Now Hall says of this species 

 " subradial plates [i. e. basals] wider than high, three of them 

 pentagonal [err. pro ' hexagonal'] and two heptagonal." There- 

 fore there was a small quadrangular radianal. That the species 

 is not a Homocrinus follows from the shape of anal x, which has a 

 broadly excavate upper surface. The shape of the cup markedly 

 resembles that of the Gotland species of Botryocrinus, and the 

 geological age harmonises. There is therefore no reason to doubt 

 the correctness of this reference. 



Botryocrinus Polyxo. 



Cyathocrinus Polyxo, Hall, 1863, Trans. Albany Inst. IV, p. 199. (Date 



of vol. 1864; author's edition issued 2 May, 1863.) 

 Homocrinus polyxo, Wachsmuth & Springer, 1886, 'Revision of Palaeo- 



crinoidea', III, p. 220, Proc. Acad. Nat. Sci. Philadelphia, 1886, p. 144. 

 Botryocrinus polyxo, Bather, 1893, 'Crin. Gotland 1 , Svensk. Vet.-Akad. 



Handl, XXV, No. 2, p 105. 

 Botryocrinus polyxo, Weller, 1900, Chicago Nat. Hist. Survey, Bulletin 



IV, Part I, p. 66. Et locc. ibi citt. 



