12 



been able to obtain a copy of the work, bnt Dr. Suess, of Philadel- 

 phia, has furnished us with a copy of the figures 15a and 156 and a 

 translation of the definition which is as follows: 

 "Amphoracrinus americanus, n. sp. 



"The whole surface is a somewhat depressed expansion of the lower 

 half of the calyx, which gives to this species a widely different aspect 

 from the type of the genus. It is also considerably smaller there 

 than A. gilbertsoni. An examination of the figures will show the 

 sculpturing of the plates which is charf^teristic of every species."' 



This definition would not be sufficient to establish a species, but 

 the figure, 15a, gives an azygous side view of an Agaricocririm and 

 shows four arm openings, upon each side of the azygous area, and 

 the figure 156 shows a basal view of the calyx, and that the ray on 

 each side of the azygous area possesses four arms and each of the 

 other three rays possesses two arms, which gives to the species fourteen 

 arms. After receiving these drawings we were able to identify four 

 specimens, from Roemer's type locality, at White Springs, Tennessee, 

 with A. americanus. We have examined a great many specimens of 

 Agar icocr inns from the Keokuk Group of Kentucky and Tennessee, 

 but have not found a single specimen of A. tuberosus, Hall, among 

 them. 



Our specimens of A. tuberosus show a great variation in size, in 

 the concavity of the calyx, and height of the vault. The proportional 

 length of the secondary radials differs, in different specimens, and in 

 some specimens the rays, on each side of the azygous area, are much 

 more prolonged than in others, this is especially the case in large 

 specimens, with a depressed convex vault; but the fundamental 

 structure and arm formula remain so constant, that there is no diffi- 

 culty in referring them to the same species. 



There has been only one thirteen-armed species, A. gorbyi, de- 

 scribed from the Keokuk Group. 



There have been three fourteen-armed species described from the 

 Keokuk Group, viz.: A. americanus, A. dissimilis and A.profundus, 

 They are all very pronounced and distinct species. 



There has only been one fifteen-armed species described from the 

 Keokuk Groux), viz.: A. iowensis, above defined. 



A. keolatkensis, as above described, lias sixteen arms. 



Agaricocrinus (?) helice described as Actinocrinus lie! ice from the 

 Waverly Group, at Richfield, Ohio, which, as above remarked, is from 

 rocks above the Waverly Group and belonging to the Keokuk, has, 



