150 PROCEEDINGS OF THE ACADEMY OF [1886. 



on a level with the second bifurcation in the other rays, and this 

 may be the case here. Miller in describing the species, we think, 

 had in mind the Silurian genus locrinus^ in which the plates of 

 the ventral sac take the form of arm plates, but these are given off 

 laterall^^ from the azygous plate and not, as it would be here, 

 from the truncated upper side of the anal piece. 



1869. Cyatbocrinus inspiratus {'!) Lyon, Trans. Amer. Philos. Soc, vol. xiii, p. 4.j7, 



PI. 27, fig. k. Keokuk gr. Crawfordsville, Ind. The description is not 



snffioient for sjiecific identification. 

 1882. C. marshallensis Worthen, Bull, i, 111. St. Mus. Nat. Hist., p. .33, Geol. Rep. 



111., vol. vii, p. 310, PI. 30, fig. 4. Kinderhook gr. Marshalltown, la. (A 



connecting link with Parisocrinus.) 

 *1S44. C. Milleri McCoy (Atocrinus Milleri), Synops. Garb. Foss. Ireland, p. 123, 



PI. 25; F. Roemer, 1855, Leth. Geogn. (2d Ed.), p. 246, PI. 4, fig. 12 ; Bronn's 



Klassen d. Thierreichs, PI. 28, fig. 6. Subcarb. Ireland. 

 (?)IS80. C. (?) stillativus White, Proceed. Nat. Mus. for 1879, p. 25S, PI. 1, figs. 9, 10; 



12th Ann. Rep. Terr, for 1878, by Hayden (Author's Ed., p. 125, PI. 36, figs. 



3 a, b). Carboniferous. Collected 30 miles west of Humboldt, Kansas. 



This is no Cyathocrinus ', it evidently belongs to the Poteriocrinidje, but 



the specimen is too imperfect to be referred properly. 

 *1865. C. subtumidus Meek and Worthen. Proceed. Acad. Nat. Sci. Phila., p. 151 ; 



Barycrinus subumidus Meek and Worthen, 1868. ibid., p. 340; also Geol. 



Rep. III., vol. V, p. 487, PI. 13, fig. 3; W. and Sp.; Barycrinus subtumidus, 



1879, Rev. i, p. 87. Keokuk limest. Green Co., 111., and White's Creek 



Springs, Tennessee. 

 1881. C. Van Horni S. A. Miller, Journ. Cinein. Soe. Nat. Hist., vol. iv (October), 



PI. 6, fig. 3. Niagara gr. Chicago, Illinois. 



(?) SPH^EROCRINUS Roemer. 



In referring Sphserocrinus to the genus Cyathocrinus (Rev. I, 

 p. 83), we overlooked the fact that Roemer's type has separate 

 dorsal canals piercing the radials. Whether this character is 

 sufficient for generic distinction is a question which has never 

 been brought up for discussion. It is in this regard worthy of 

 notice that this structure occurs exclusively in species from the 

 Silurian and Upper Devonian, never in the Carboniferous, neither 

 in Cyathocrinus nor other genera. Whether all species of Cyatho- 

 crinus from Gothland and Dudley possess this structure, cannot 

 be ascertained from the figures, but if they do, it may form tlie 

 basis of a separation which seems to us very desirable. If the 

 genus Sphserocrinus is accepted, it will probabl}' include not only 

 Sphaerocrinus geometricus Goldfuss, Roemer's typical species, 

 but many others. 



