liO FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



the centres of the plates of the rays are proportionally less de- 

 veloped. 



In single individuals, this form, when compared with the preceding, 

 might be regarded as a distinct species. 



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

 Western New-York. C. A. White, collector. 



CACABOCRINUS GLYPTUS ( n. s.). 



Body large, very depressed-spheroidal. Dome elevated and termina- 

 ting in a subcentral process, strongly lobed at the arm-bases. Base 

 flattened : basal plates of medium size, mostly covered by a large 

 column. First radial plates large, much wider than high. Second 

 xadials quadrangular, little more than half as high as the first, 

 twice as wide as high. Third radials pentangular, a little longer 

 than the second, once and a half as wide as the greatest height; 

 supporting upon each upper margin a series of two supraradials, 

 the first twice as large as the second, which supports the first 

 arm-plates. 



First interradial plate large, subcircular, nine-sided, supporting 

 one hexagonal plate less than half as large as the first radial : 

 three plates in the third series, the central one uniting with the 

 dome-plates, and the two smaller plates resting partly upon the 

 lateral margins of the second interradial, and partly upon the 

 lateral margins of the first supraradials; these aid in supporting 

 the second supraradials and first arm-plates. 



Arms two from each ray at their origin, the bases strong and pro- 

 truding. 



Surface of calyx plates marked by interrupted lines of nodes, prin- 

 cipally radiating from the centre to the angles. A sharp carina 

 passes along the centre of each ray from the basal plates to the 

 arm-bases, rising in angular nodes on the centre of each plate : 

 sutures channelled. 



This species difiers from the preceding in the proportions of the plates: 

 the first interradials are shorter, the arm-bases somewhat longer and 

 more protruding; while the surface is marked by a few lines of nodes 

 from the centres of the plates to the angles, instead of numerous and 

 continued strise passing at right angles to the faces. 



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

 near Pavilion, Genesee county. 



