342 HAWAIIAN AND OTHER PACIFIC ECHIXI. 



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

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



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

 erous pedicellaria; 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 



plated Pachycentrolus. 



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 pedicellaria; with a 



lateral tooth on left side near tip Heliocidaris 



Pore-pairs u.sually 4r-7, rarely 8-10; test thin or moderate; valves of 



globiferous pedicellaria; with no lateral teeth Strongylocentrotus. 



ECHINOSTREPHUS. 



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

 Type-species, Echinoslrephus aciculalus 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, aciculalus 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- 

 lalus, 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) 

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

 to which he gave the name pcnlagonus.^ The two species -seem to be quite 

 distinct and arc 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 u.sually 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 aciculatiu. 



Echinostrephus aciculatus .\. Ag. 



Echino.strephus aciculatus A. .Xga-s-siz, 1863. Hull. M. C. Z., I, p. 20. 



Echinostrephus molare A Ag!us.siz and Clark, 1907. Bull. M. C. Z., L. p. 242. Non BlainviUc, 18"25. 



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



The disc()\ (M y (lint <icinilntus is not identical witli molaris gives added interest 

 to this uni(iu(^ genus mikI tlic sjiecific characters have been studied in great detail. 



' This conclusion is confirmed by examination of Yoshiwara's si>ocunen8. 



