308 New Species of Crinoidea from the 



depression. Sub-radial jslates of medium size, three ap- 

 parently pentangular from the straightness of the lower 

 side, the other two larger and hexagonal from the same 

 cause. First radial plates larger than the sub-radials, and 

 nearly twice as wide as high, the upper margins slightly 

 concave. Second radials long, pentangular, much higher 

 than wide ; those of the postero-lateral rays slightly trun- 

 cated at the summit, the first arm plates resting on the 

 lateral slopes of the same and widely divergent. First 

 anal plate elongate, pentangular, placed obliquely between 

 two sub-radials and the first radial of the right postero- 

 lateral ray ; the remaining two or three plates seen are 

 minute. 



The arms, as far as known, bifurcate on the second 

 radial, the divisions widely divergent, with one or two (per- 

 haps more) bifurcations above, which are less strongly 

 divergent. The first arm plates the longest and strongest; 

 those above are short and wedge-form, strongly rounded 

 on the back, giving a semi-cylindrical form to the arm and 

 its divisions. 



This species is closely allied to S. divaricatus of the 

 Warsaw limestone; but differs in the more concave base, 

 and the larger and longer second radial plates ; the bifur- 

 cations take place on the sixth and eighth plate, and are 

 more numerous, and the arm plates are more rounded 

 on the back. 



Geo/og-ical formation and locality. Burlington lime- 

 stone, Burlington, Iowa. Collection of Rev. W. H. Bar- 

 ris. 



Scaphiocrinus Halli (n. s.) Body small, calyx short, 

 broadly cup-shaped. Basal plates small, pentagonal, an- 

 gular at the top. Sub-radials hexagonal, except on the 

 anal side. First radials of medium size, pentagonal, about 

 once and a half as wide as high. Second radials elon- 

 gated, strongly constricted at the middle, and somewhat 



