342 HAWAIIAN AND OTHER PACIFIC ECHINI. 



pedicellariae short, abruptly rounded at tip and with 6-8 con- 

 spicuous teeth there; pore-pairs 7-10 Loxechinus. 



Usually two, not rarely three or more oculars insert; valves of globif- 



erous pedicellariae with a lateral tooth only on left side. 

 Oculars V and IV insert, often III also, sometimes II and not rarely 



all; test not very stout; buccal membrane with scattered plates Ccenocenlrotus. 

 Oculars I and V insert, rarely IV or II also; test very stout, thickly 

 covered with tubercles; buccal membrane more or less heavily 



P lated Pachycentrotus. 



Pore-pairs in arcs of 4-10; if fewer than 6, valves of globiferous pedicel- 



laria; with tubular blade, prominent end tooth and no lateral teeth. 

 Pore-pairs 7-10; test stout; valves of globiferous pedicellarise with a 



lateral tooth on left side near tip Heliocidaris 



Pore-pairs usually 4-7, rarely 8-10; test thin or moderate; valves of 

 globiferous pedicellariae with no lateral teeth Strongylocentrolus. 



ECHINOSTREPHUS. 



A. Agassiz, 1863. Bull. M. C. Z., I, p. 20. 



Type-species, Echinostrephus aciculatus A. Agassiz, 1. c. 



A careful comparison of the "Albatross" material from the Hawaiian Islands 

 with that in the M. C. Z. collections from Mauritius, and from the Pacific Ocean, 

 shows that this interesting genus contains two species, aciculatus A. Ag. not 

 being identical with Echinus molaris Bl. Owing to the fact that in the "Re- 

 vision" they are regarded as identical, and the figures given are those of acicu- 

 latus, the description also being based on that species, Yoshiwara (1898, Ann. 

 Zool. Jap., II, p. 59) on finding specimens of the true molaris (PI. 105, figs. 10,11) 

 in Japanese waters (Bonin Islands) was misled into describing it as a new species 

 to which he gave the name pentagonus. 1 The two species seem to be quite 

 distinct and are to be separated by the following characters : 



Pore-pairs 3; ambitus more or less evidently pentagonal; 'genital and ocular plates with 



no tubercles except on outer margin; test usually more or less bright green . . molaris. 



Pore-pairs 4; ambitus circular; genital and ocular plates with more or less numerous 



tubercles; test dull purplish or greenish aciculatus. 



Echinostrephus aciculatus A. Ag. 



Echinostrephus aciculatus A. Agassiz, 1863. Bull. M. C. Z., I, p. 20. 



Echinostrephus molare A. Agassiz and Clark, 1907. Bull. M. C. Z., L, p. 242. NON Blainville, 1825. 



Plates 95, figs. 23, 24; 105, fig. 9. 



The discovery that aciculatus is not identical with molaris gives added interest 

 to this unique genus and the specific characters have been studied in great detail. 



1 This conclusion is confirmed by examination of Yoshiwara's specimens. 



