318 Neiu Species of Crinoidea from the 



Forbesiocrinus, but only partially, as the genus is de- 

 fined. 



The very peculiar feature of armlets on one side only 

 of the arms in place of tentacula is remarkable, but it has 

 not been determined whether the plates of the armlets 

 bear tentacula or not. The column has been removed, 

 and the basal plates, in their incipient development, are as 

 in Ic/ithj/ocrinus ;* while the sub-radial plates, in their 

 outer angles, reach beyond the column facet. 



The absence of interradial and anal plates, together 

 with the entire absence of a calcareous dome, so far as 

 we can perceive, indicates that these parts may have been 

 covered by a fleshy envelope. 



The angular form of body, the nodose-carinate rays, 

 and other features described, afford the most peculiar and 

 interesting form of the genus which I have seen. 



Geological formation and locality. Burlington lime- 

 stone, Burlington, Iowa. Collection of Dr. O. Thieme. 



Forbesiocrinus spinifer (n. s.). Basal plates very small, 

 the sub-radials projecting in five salient points beyond the 

 column. First radial plates heptagonal (as far as deter- 

 mined) ; second radials hexagonal, shorter than the first ; 

 third radials triangular, with the lower side curved down- 

 wards, and the centre produced into an elongate spine, 

 supporting on its upper sloping sides the supra-radial 

 plates in two series of three each. The upper ones of 

 these are bifurcating plates, bearing a short spine on the 

 centre ; each one supporting two free arms, w^hich bifur- 

 cate or throw off armlets at intervals above. Interradial 

 areas occupied by a single plate each, so far as observed. 

 Anal area unknown. 



The interradial plates are angular or sub-carinate in the 

 middle, the first one produced into a short, spine-like node 



* See Vol. II. Pal. N. Y. page 195, plate 43, fig. 2 f. 



