282 Neiv Species of Crinoidea from the 



not more than one lialf iiicli in diameter, and the largest 

 about one and one fourth inches, all showing the same pe- 

 culiar characters more or less distinctly expressed. This 

 variety of form and development of the parts named may 

 lead in a larger collection to a separation as distinct spe- 

 cies of those which are here seen to be distinct varieties. 



Geological formation and locality. Burlington lime- 

 stone, Burlington, Iowa. Collection of C. A. White. 



Agaricocrimis {Amphoracrinus) excavatus (n. s.). Body 

 pentagonal, flat below, with the centre abruptly depressed 

 or excavated, pyramidal above ; height equal to two thirds 

 the width. The depression of the base consists of a deep, 

 circular cavity, the bottom of which includes the plates of 

 the body as far as the middle of the second radial plates, 

 while the upper part of these and the lower part of the 

 third radials form the sides of the cavity ; the space be- 

 tween this and the arm bases is somewhat rounded. Basal 

 plates small, forming a pentagon. First radials hexago- 

 nal, wider than long ; second radial plates wider and not 

 so high, five and seven-sided ; third radial plates propor- 

 tionally very large, pentagonal, obtusely wedge-form above, 

 supporting on each upper side a series of short, broad 

 plates, on which rest tlie arm plates proper. 



First interradial plates hexagonal in the antero-lateral 

 spaces, succeeded by two very narrow and much elongated 

 plates in the second range, which reach from the inner 

 margin of the cavity to the arm openings. In the postero- 

 lateral spaces, the first interradial plates are elongate, 

 reaching to the top of the third radial phite, or higher. 

 First anal plate sub-hexagonal, somewhat elongate, sup- 

 porting three larger elongate plates in the second range, 

 with numerous small polygonal plates above. The anal 

 area is somewhat protruding, and situated about midway 

 between the arm bases and the top of the dome. Dome 

 composed of variously sized plates, the large ones tubercu- 



