NO. 5 CLARK : ECHINI OF WARMER EASTERN PACIFIC 293 



Echinometra VanBrunti A. Agassiz 



Plate 46, Fig. 25 



Echinometra VanBrunti A. Agassiz, 1863, p. 21. 



Heliocidaris stenopora H. L. Clark, 1912, p. 351, pi. 95, figs. 18-22; pi. 



104, figs. 1-3; pi. 110, figs. 4,5. 

 Echinometra VanBrunti Mortensen, 1943a, p. 373, pi. 45, figs. 1-3. 



This is apparently the commonest littoral sea-urchin of the tropical 

 Eastern Pacific. The Velero collection contains 658 specimens taken at 92 

 stations. They range in size from young ones, nearly or quite circular, 5 to 

 10 mm in diameter, to large adults with a long axis exceeding 70 mm. 

 Normal large adults have the lesser diameter nine-tenths of the longer, 

 and the height is very generally about one-half the length. But there is 

 considerable diversity and individuals having the normally lesser axis 

 nearly or quite equalling the longitudinal axis are not very rare. There 

 seems to be no doubt that Heliocidaris stenopora H. L. Clark is based 

 on a large Echinometra Van Brunti as A. H. Clark, Ziesenhenne and 

 Mortensen have recently pointed out. In the Velero collection there are 

 some specimens in which the ambitus is nearly circular but they are com- 

 monly less than 40 mm in diameter and not one would be identified as 

 stenopora, as the tuberculation of the test is not coarse enough and the 

 primary spines are not sufficiently stout. Mortensen inclines to recognize 

 a variety rupicola although it occurs in the same areas as typical VanBrunti 

 but the hundreds of specimens in the Velero collection do not, in my 

 opinion, warrant the recognition of such a form. 



It was hoped and rather expected that among the Echinometras in the 

 present collection, there would be from the Galapagos and Socorro Islands, 

 some specimens of E. insularis but not one t3Tical example has been found. 

 Some specimens from Costa Rica have only 5 pore-pairs in the ambulacra 

 at the ambitus but they have 6 pairs abactinally and the general appearance 

 and spinulation is like that of VanBrunti from the same region. Unfor- 

 tunately there is but a single young individual from Clarion Island, and 

 only two lots from Socorro. This series includes one very large adult and 

 32 small ones and they are typical VanBrunti. There are 78 specimens 

 from some 20 stations in the Galapagos but none of them represent 

 insularis, which justifies the suspicion that that supposed species is not 

 really valid. 



The color of VanBrunti is remarkably uniform although the shade 

 shows no little diversity. The basic color may be designated as violet 

 especially when seen from below. There is a tendency on the one hand 



