12 



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

 phia, has furnished us with a copy of the figures lor/ and 15/) and a 

 translation of the definition which is as follows: 



"Amphoracrinus americanns, n. sp. 



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

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

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

 than A. (jillK'rfsoui. An examination of the figures will show the 

 sculpturing of the plates which is characteristic of every species." 



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

 the figure, 15ff, gives an azygous side view of an Afjaricncrinu:^ and 

 shows four arm oix'uings, ui^on each side of tlie azygous area, and 

 the figure 15& 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 po.ssesses two arms, which gives to the species fourteen 

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

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

 with A. ai)ieric((itiifi. We have examined a great many speeinuMis of 

 Af/aricncriiiiis from the Keokuk Group of Kentucky and Tennessee, 

 l)ut liave nol found a single specimen of A. iKhcromis, Hall, among 

 tliem. 



Our specinu'us of J. hihcra^iiiK 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 eacii side of the azygous area, are much 

 . more prolonged than in others, this is es[)ecially the ease 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. 



TluTc has been only one thirteen-armed s])i>c:cs. .1. f/n)7<///. de- 

 scribed from the Ki'okuk (iroup. 



There have been three fourteen-armed species ileseribed from the 

 Keokuk Group, viz.: A.<iiiic)'ir(iiins, A.disaimilis and .1. pi-afinidiix. 

 They are all very pronounced and distinct species. 



There has only l)een one fifteen-armed species deseribetl from the 

 Keokuk Grou]), viz.: ^1. iuireiixis. above defined. 



A. kcokiikfiisiii, as above described, has sixteen arms. 



Agar icocr inns {?) hrlicc described as Arfiiiorriiiiis helice from the 

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

 rocks above the Waverly Grou]) and belonging to the Ki'oknk. has. 



