568 Verrill, Notes on Radiaia. 



No. 8. — Additional Observations on JEchinoderms, chiefly from the 

 Pacific coast of America. By A. E. Verrill. 



Presented January, 1871. 



Atlantic Species. 

 Pteraster Danae Verriii. 



Pioc Boston See. Nat. Hist, xii, p. 386, April, 1869. 



Plate IX, figures 11, ll'\ 



Upper sitrface moderately convex ; radius of disk to that of rays as 

 1 : 1"18; rays broad, subtriangular, the tips recurved so as to expose 

 the end of the ambulacral grooves on the upper side. The dorsal 

 membrane is perforated by minute scattered pores, and numerous 

 small, slender, acute spines project from its surface at regular inter- 

 vals ; these are larger on the disk and quite small on the outer part of 

 the rays. Central opening small, somewhat rounded, surrounded by 

 small spines. Dorsal paxillae, as seen when the dorsal membrane is 

 removed, elevated and rather stout, surmounted at the summit by six 

 to ten, slender, acicular, divergent spinules, one of which is usually 

 larger, and projects through the membrane, Rays beneath bordered 

 on each side by about thirty, slender, transverse, spine-like ribs, which 

 project but slightly beyond the margin, and are connected by the web- 

 like membrane quite to their ends. Interambulacral plates thin, each 

 usually bearing four very slender, elongated spines, many of them 

 with small pedicellariae near the tips ; the inner one considerably short- 

 est ; all connected together by a web, which retreats between the 

 points to a considerable extent ; near the mouth there are often five 

 spines. At each interradial corner of the mouth there are ten long, 

 slender, pointed spines, the six middle ones about equal in length, the 

 two outer ones on each side much smaller, the outermost considerably 

 smaller than the preceding ; just back of these, and side by side, are 

 two long, slender, somewhat curved, acute spines, about equal in 

 length to the longer ones of the group in front of them. 



Radius of disk -37 of an inch ; of rays '5 7 ; width of rays at base '50 ; 

 elevation of back "35 ; length of longest transverse ribs of the rays 

 beneath '15 ; of interambulacral spines '00 to '08 ; of the spines at 

 mouth angles, about '08. 



This species was labeled "Rio Janeiro?" It was perhaps from 

 dredgings made in 30 fathoms off the east coast of Patagonia, — J. D. 

 Dana, U. S. Expl. Expedition. 



