29 



In the subpsntagonal outline of the calyx, short form, and in the 

 character of the vault this species allies itself with Agaricocri- 

 nus; but in the plates of the calyx, and in their arrangement, it is a 

 true Batocrinus. If the arms were preserved, we might be disposed 

 to refer it to Agaricocrinus, notwithstanding the plates and form of 

 the calyx. We have referred it to Batocrinus with doubt. If there 

 has ever been a link discovered that connects Batocrinus with 

 Agaricocrinus, by any chain of development, it is to be found, in 

 this species. All authors who lay stress upon the characters of the 

 vault will unhesitatingly refer this species to Agaricocrinus. But 

 no eighteen armed Agaricocrinus has ever been found, in the Burl- 

 ington Group, and only one in the Keokuk, and it is a pronounced 

 Agaricocrinus. Typical Agaricocrinus appear in the Chouteau 

 with ten and twelve arms and they are quite as early as any Batocri- 

 nus. Batocrinus with eighteen and more arms are common in the 

 Burlington. This cannot be the species through which Batocrinus 

 developed into Agaricocrinus, nor through which Agaricocrinus de- 

 veloped into Batocrinus, because it is not found in rocks early 

 enough for such transition. It is only indicative of an apparent 

 affinity, when both genera were in the mature state of their exist- 

 ence. The stratigraphical position with the eighteen armed struct- 

 ure is in favor of classifying it with Batocrinus. 



Found in the Burlington Group, by R. A. Blair, near Sharon, in 

 southwestern Missouri, and now in the collection of S. A. Miller. 



BATOCEINUS DOUGLASSI, n. Sp. 



Plate II, Fig. 20, view opposite the azygous area. 



Species medium size, biturbinate. Calyx obconoidal, about twice 

 as wide as high. Radial ridges rounded, and all the plates radiately 

 sculptured. Truncated only the diameter of the column. 



Basals form a very short hexagonal disc. First primary radials 

 much wider than long, three hexagonal, two heptagonal. Second 

 primary radials about half as large as the first, and about half as 

 long as wide, quadrangular. Third primary radials larger than the 

 second, pentagonal, axillary, and support on each upper sloping side 

 a single secondary radial which is axillary, and, upon the distal sides, 

 support four tertiary radials, before the arms become free ; upon each 

 proximal side there is a single tertiary radial, which is axillary and 

 supports three quaternary radials before the arm becomes free. 



