15 



by three in the third range, one of which is elongated and curves 

 over so as to unite with the plates of the vault. There are two plates, 

 in the fourth range, even with the superior end of the elongated 

 plate belonging to the third range, that unite with the plates of 

 the vault. 



The vault is depressed, convex, and covered with polygonal, 

 slightly convex plates of very unequal size. The orifice is small 

 and subcentral. 



This species is so distinct from all others that no comparison 

 with any of them is necessary. Heretofore, there has never been 

 described a twenty- armed species of Physetocrinus, except Physe- 

 iocrinus copei, which is far removed from this species, in all 

 other respects. 



Found by F. A. Sampson, in whose honor we have proposed 

 the specific name, in the Burlington Group, at Sedalia, Missouri, 

 and now in his collection. 



DORYCRINUS ALABAMENSIS, n. 8 p. 



Plate III, fig. 15, basal view; fig. 16, summit view; fig. 17, 

 azygous side; the specimen illustrated is a 

 cast from the chert. 



Species medium size, calyx and vault subequal, outline sub- 

 spheroidal, arms directed below a horizontal line. Calyx basin- 

 shaped, rounded below, more than twice as wide as high. 

 Ambulacral openings directed horizontally or below a horizontal 

 line and not visible in a basal or summit view. This species is 

 founded upon a very perfect cast in chert, of the interior of the 

 test, and, therefore, does not show the surface ornamentation, or 

 surface character of the plates except it shows the existence of 

 radial ridges, by the radial furrows within the radial plates. 



Basals form an hexagonal disc, very little larger than the 

 diameter of the column, with a strongly marked re-enfering angle 

 on the azygous side. First primary radials, a little larger than 

 wide, three hexagonal, two heptagonal. Second primary radials a 

 little wider than long, three pentagonal, two hexagonal, caused by 

 the slight truncation of some of the angles, by the plates, in the 

 second interradial ranges. Third primary radials about the size 

 of the second, three hexagonal, two pentagonal, axillary and sup- 

 porting, upon each superior sloping side, two secondary radials, 



