142 FIFTEENTH KEPORT ON THE CABINET OF NAT. HISTORY. 



some specimens, form erect lamellae by their greater elevation : 

 also the plates of the radial series are marked by a strong central 

 ridge which forms subangular or lanceolate nodes on the first and 

 second radial plates, becoming obsolete on the third radial and 

 first supradials; while the second supraradial plates are elevated 

 into a broad angular ridge. 



This species bears considerable resemblance to G. sculptus, in generai 

 form and surface markings; but in structure and number of arms, it is 

 very unlike. 



Geological formation and locality. In the limestone of the Upper Hel- 

 derberg group : Western New- York. 



The Devonian genera of Crinoidea, Ceramocrinus and Epactocrinus 

 of MuLLER, and Myrtillocrinus of Sandberger, possess some cha- 

 racters in common, which render it difficult, with the descriptions 

 and illustrations within my reach, to determine the relations of these 

 genera, or the range of characters which may be admitted under 

 the several designations. Desirous of avoiding the multiplication of 

 synonyms, I have placed the following species under the Genus 

 Myrtillocrinus, until we are able to ascertain more fully its entire 

 characters. 



GENUS MYRTILLOCRINUS (Sandberger). 



MYRTILLOCRINUS? AMERICANUS ( n. s.). / I , y 



Body small, broadly ovoid, largest at the upper end. Base truncated 

 by the attachment of a proportionally large column, which has 

 a quadrangular foramen. Basal plates five, very small, forming a 

 low ring around the top of the column. Subradial plates five, 

 alternating with the basals, hexagonal, but with the lower margins 

 so nearly in a line that they appear pentagonal : height and width 

 about equal, widening upwards. Radial plates large, hexagonal, 

 a little higher than wide; the lateral margins subparallel. Area 

 of the arm-cicatrix large, covering the greater portion of the plate; 

 its surface vertical, and elevated above the margins of the plate, 

 subelliptical in form, with a small central foramen, and the upper 

 margin excavated by the passage leading from the arms to the 

 cavity of the body. 



Dome consisting (apparently) of but five plates, somewhat unequal, 

 alternating with the radials; their surfaces elevated into strong 

 nodes, which are each covered with unequal pustules. 



Surface of calyx-plates depressed-convex. 



