148 FIFTEENTH KEPOKT ON THE CABINET OF NAT. HISTORY. 



Surface of radial plates striate. A lanceolate space embracing the 

 full width of the interradial plates at the base, and terminating 

 in a narrow point above, is striato - granulosa with transverse 

 undulating striae ; while the area between this and the pseud- 

 ambulacral field is marked by strong, longitudinal, abruptly- 

 undulating striae. 



The largest specimens of this species which have been observed, are 

 scarcely half an inch in height. In an older specimen, the greatest width 

 is equal to the height ; while in a younger one, it is less. The larger of 

 these specimens before me is the one from which the original figure and 

 description of Mr. Conrad was made. 



Geological formation and locality. In the shales of the Hamilton group: 

 at Moscow, Livingston county. 



NUCLEOCRINUS LUCINA ( n. s.). ^ 



Body elliptical, the greatest width above the middle, deeply penta- 

 lobate near the base and less deeply above : base almost flat. 

 Basal plates nearly on a plane with the radials at the base of the 

 pseudambulacral fields, and bearing an elongate node in the 

 centre. Radial plates short, embracing only the base of the 

 pseudambulacral fields. Interradial plates elongate, broad lanceo- 

 late, reaching the summit. Anal plate prominent above, not 

 reaching the summit, leaving narrow portions of the interradial 

 plate on each side. Centre of the summit a little flattened : the 

 oral plates not determined. 



Surface striato-granulose. 



This species is more deeply lobed, and comparatively broader at base, 

 than the N. {Olivanites) angularus of Lyon; and is in all respects a very 

 distinct species. Length from one-half to one inch. 



Geological formation and locality. In the shales of the Hamilton group: 

 Livingston county and elsewhere. C. A. White, collector. 



NUCLEOCRINUS LUCINA, var. 



A large specimen, possessing the same general characters as the pre- 

 ceding, is more expanded in the upper part of the body, with the base 

 proportionally narrower. This may possibly be only a variety of form, 

 which a larger number of specimens might show to be a phase common 

 to older individuals. 



