320 Neiv Species of Crinoidea from the 



This small species is easily distinguished by the arms 

 becoming free within the limits of the radial series, the 

 single interradial and anal plate, and the simplicity of the 

 arm structure. 



Geological formation and locality. Burlington lime- 

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

 ris. 



Forbesiocrinus astericBformis (n. s.). The body and 

 arms together form an irregular, five-rayed star, with the 

 ends of the rays clavate ; these are made by the radial 

 series and the united parts of the arms, which spread al- 

 most horizontally from the body ; the clavate character is 

 given by the armlets, which are closely incurved. The 

 lower part of the body is slightly convex; the dome ap- 

 pears to have been somewhat elevated. Basal plates 

 small, and appearing only as an upper joint of the col- 

 umn. Sub-radials small, four pentangular and equal in 

 size, one larger and irregularly hexagonal. Radial series 

 consisting of four, rarely of five plates : the first of me- 

 dium size, wider than high, heptagonal ; the second and 

 third broad, short, sub-hexagonal; the upper radial plate 

 is heptagonal, very obtusely angular above. The ray be- 

 yond is composed of a double series of plates, united at 

 their inner margins as far as the fourth or fifth plate, where 

 they separate and form two free arms. The fourth plate 

 of each series above the last radial plate gives origin on 

 its outer side to an armlet, and the third plate beyond 

 o-ives oriijin to a second armlet ; the second above this 

 supports a pair of armlets, each armlet again dividing into 

 two, three, or four branches. This arrangement is repeated 

 on each ray, making five difterent sets or clusters. Each 

 arm or armlet is composed of a single series of short, com- 

 paratively strong plates; those above the last bifurcation 

 appear quadrangular and equal- sided. First interradial 

 plate elongate, heptagonal ; the second range consists of 



