218 HAWAIIAN AND OTHER PACIFIC ECHINI. 



abbreviated by Lamarck to carinatus and this shorter form has been in constant 

 use for a century; but it must of course give way to the original name. The 

 genus Brissus is common and wide spread in shallow water, throughout the 

 tropics. Although three species were recognized by Mr. Agassiz in the Revi- 

 sion, I can distinguish but two, and even those two are not sharply differen- 

 tiated. Aside from the differences given in the following key, the slender 

 tridentate pedicellariae seem to furnish the only good specific character. Mr. 

 Agassiz's Brissus damesi (1881. Challenger Report, p. 197) is, as he himself 

 stated, based on such immature specimens that their generic position is quite 

 uncertain. I have seen no specimens and am unable to give the species any 

 place in the present work. Doderlein (1885. Arch. f. Naturg., 51, 1, p. 108) 

 has described a species from Japan, B. agassizii, but as the only distinctive 

 character he gives is based on the length of the posterior petals, a feature 

 which is very variable in B. latecarinatus, I cannot distinguish this Japanese 

 species. 



Key to the Species of Brissus. 



Test nearly or quite vertically truncate posteriorly, not overhanging; interambulacrum 



5 little or not at all carinate dorsally brissus. 



Test obliquely truncate posteriorly, with periproct overhanging subanal plastron; inter- 

 ambulacrum 5 markedly carinate dorsally, at least in adults latecarinatus. 



Brissus brissus. 



Spatangus brissus (var. unicolor) Leske, 1778. Add. ad Klein, p. xx, 182. 



The combination Brissus brissus has not previously been used but, as 

 explained above, must be adopted for the genotype. The present species is 

 wide spread in the tropical Atlantic and also occurs in the Mediterranean. It 

 is known from the Azores, Canary, and Cape Verde Islands as well as from 

 Florida, Bermuda, and the West Indies as far south as Tobago. It is a curi- 

 ous fact that the largest specimens from the western Atlantic are not near] 

 large as those from the eastern islands and the Mediterranean Sea. Otherwise 

 lam unable to find any noteworthy differences. Mortensen (1913. Mitt. Zool. 

 Stat. Neapel, 21, p. 31, 32) has fully described, with excellent figures, t he varied 

 pedicellariae of this species as shown by Mediterranean specimens. In West 

 Indian specimens, globiferous pedicellariae may be wholly wanting; when 

 present, the valves have the blade slope more gradually into the base than is 

 shown in Mortensen's figure. Slender tridentate pedicellariae are rare but 



