38 HAWAIIAN AND OTHER PACIFIC ECHINI. 



broader, straighter, and more acuminate than those of subdepressus; their 

 length is .35-1.00 mm. In 1911 (Ann. Mag. Nat. Hist., ser. 8, 7, p. 595) I 

 named this species as the type of Agassiz's genus Stolonoclypus should it ever 

 be desirable or necessary to use that genus, and added that prostratus was a 

 synonym of subdepressus. It now seems that prostratus can stand on its own 

 merits and hence is itself the type-species of Stolonoclypus. 



Clypeaster rotundus. 



Stolonoclypus rotundus A. Agassiz, 1863. Bull. M. C. Z., 1. p. 25. 

 Clypeaster rotundus A. Agassiz, L872. Rev. Ech., pt. 1, p. LOO. 



Plates 122, figs. 5-7; 123, figs. 25-27; 128, fig. 6; 132; 133. 



This fine species is the West coast representative of prostratus and is really 

 nearer that species than it is to subdepressus. It is readily distinguished from 

 the other West coast species by the shape of the petals and the fine tubercula- 

 tion of the test (PI. 128, fig. 6). The Albatross took a single specimen of 

 rotundus at Station 2796, Gulf of Panama, 33 fms., and as it is a particularly 

 fine one, and the species has never been figured, I have given here photographs 

 of it (Pis. 132, 133). 



The primary spines of rotundus are more or less rough or serrulate, and the 

 abactinal ones (PI. 122, figs. 5, 6) are slightly expanded at tip. The miliary 

 spines (PI. 122, fig. 7) are cylindrical or terete. Pedicellariae seem to be some- 

 times very scarce, as in one specimen only three minute tridentate and one tri- 

 phyllous were found. The valves of the tridentate (PI. 123. figs. 26) are only 

 about .15 mm. long and are notably broad. In another specimen there were 

 a number of tridentate pedicellariae with valves over .(50 mm. long and a 

 more usual style of blade (PI. 123, fig. 27). In a third specimen, ophicephalous 

 pedicellariae were found but they showed no peculiarities. 



Clypeaster subdepressus. 



Echinanthus subdepressa Ciav. lS2o. Ann. Phil., 26, p. 127. 



Clypeaster subdepressus Agassiz, l^;<>. Mem. Soc Sci. Nat. Neuchatel, 1. p. 187 



Plate 123, figs. //. l.'. 



The presence of quadridentate pedicellariae (PI. 12:}. figs. //. 1J< is one of 

 the characteristics of this West Indian species. The valves of these pedicellariae 

 are .45-1.00 mm. long and very narrow, but slightly expanded at the tip. The 



