312 Ven'ill, Notes on Radiata. ■ 



derms,* from Mr. Pease of the Sandwich Islands. Its origin is entirely 

 doubtful. It is destitute of spines and in the same state of preserva- 

 tion as a Bendraster exee7itricus, which came with it. 



EchinOglyCUS Stokesii Gray; A. Ag, Bulletin M. C. Z., p. 2r,, 1863. 



Encope Stokesii Agassiz, Mon. ScuteUes, p. 59, Tab. 6a, figs. 1 to 8, 1841 ; Liitken, 

 Bidrag til Kundskab. om Echin., p. 65, 1864. 



This species was found abundant on a sandy beach near Panama, 

 at low-water mark. Dr. Ltitken's specimens were from Punta Arenas, 

 whence he has sent examples to us. It has also been described from 

 Guayaquil and the Galapago Islands. 



The larger specimens from Panama are two inches long; 2"15 

 broad ; '25 high at center ; from center to end of anterior ambulacral 

 ray "55 ; to end of anterior-lateral '5 ; posterior-lateral "48 ; center to 

 genital openings -08 ; width of anterior ambulacral ray '25 ; its cen- 

 tral area 'll ; width of the four lateral rays -27 ; central area -11 ; cen- 

 ter to anterior lunule "8 ; to anterior-lateral "73 ; to posterior-lateral -67 ; 

 to posterior perforation 'GS ; its length '2 ; breadth "1 ; mouth to anal 

 opening "42. The form is nearly circular, the posterior interambula- 

 crum usually slightly truncated. Lower surface flat, upper side most 

 elevated at the center of the rosette, which is behind the middle ; test 

 rather thin and brittle. Six lunules or perforations, the posterior one, 

 even in very young specimens, is a rounded oblong perforation, in 

 the adult specimens becoming twice as long as wide ; the lateral ones 

 appear at first as shallow notches in the edge, which gradually become 

 narrow, long or oval, and in the larger specimens all, except the ante- 

 rior one, become closed at the edge. In young specimens the poste- 

 rior-lateral notches appear first, the anterior one not being apparent 

 in a specimen '6 of an inch in diameter; in the larger specimens its 

 outer edges are in contact and doubtless finally unite. Ambulacral 

 rays short and broad, a little elevated above the general surface ; the 

 anterior odd one longer and narrower than the others ; posterior pair 

 shortest, but about equal in width to the anterior pair ; along the 

 middle of each there is a narrow naked line. Genital openings usually 

 five, large and regulai', sometimes the posterior one is double or irreg- 

 ular. Spines of the upper surface crowded, uniform, very slender, 

 enlarged or clavate at the tips; the edge fringed with larger and 



* The species received in this collection are as follows : Linckia unifascialis Gray, 

 Nidorellia armata Gray, Oreaster occidentalis Verrill, FTeliaster Kubiniji Xant., Culcita, 

 sp., Dendraster excentricus Ag., Encope grandis Ag., E. occidtntalis V., Astriclypeus 

 Mannii V. 



