21 



arranged in different forms, while the sutures are broad and 

 deep channels instead of indistinct lines. 



Geological Formation and Locality. In limestone of the age 

 of the Niagara group, Racine, Wisconsin. Dr. P. B. Hoy, 

 T. J. Hale, James Hall. 



GENUS GLYPTOCRINUS, Hall. 

 GLYPTOCRINUS nobilis, (n. s.) 



Description. Body large, robust, from base to the first 

 bifurcation of the ray, sub-hemispherical ; arm bases above 

 this prominent, giving a strongly lobed form ; dome highly 

 elevated, the distance from the base of the free arms to the 

 base of the proboscis being once and a-half as great as 

 the distance below. Proboscis strong, sub-central, entire 

 length unknown. Basal plates of moderate size, spreading 

 almost horizontally from the column. First radial plates 

 large, second radials hexagonal, much wider than high ; 

 third radials broadly pentangular, Supporting on each upper 

 sloping side a series of four supra-radials; the upper one of 

 which is a bifurcating plate, and supports on the upper oblong 

 sloping edges a series of arm plates ; giving eight arms to 

 each ray, so far as determined. 



First interradial plate large, six or seven sided, with two 

 smaller plates in the second range, three in the third, and 

 several small polygonal plates above filling the interbrachial 

 spaces, and connecting with the dome plates. Anal series 

 unknown. Dome composed, near the base, of small polygonal 

 plates, gradually increasing in size towards the proboscis ; the 

 dome is strongly lobed, and the depressions correspond with 

 the interbrachial spaces. Surface of calyx plates marked by a 

 single set of strong radiating ridges, which connect at the 

 sutures with those of the adjoining plates; the interspaces 

 occupied by one or more small round nodes, which are some- 

 times confluent. The ridge along the radial series is much 

 the strongest, and forms a node on the centre of each plate. 

 The dome plates are marked by similar, but less distinct lines, 

 and a small round node on the center of each plate. 



This species differs from G. decadactylus (Pal. N. Y. Vol. 2) 

 in the larger size ; the shortness of the base ; the very large 

 dome, and strong proboscis ; as well as in the surface marking 

 and greater number of arms. 



Geological formation and locality. In limestone of the age 

 of the Niagara Group, Racine, Wisconsin. Dr. P. R. Hoy, 

 James Hall. 



