112 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Indian species, depressa and in 1876, de Loriol described the Mauritian form, 

 alexandri. In 1880, Bell described the South African species, crassa, for which 

 he instituted Palaeolampas, a genus I am not prepared to accept. Cotteau, 

 in 1889, based a new species, blanchardi, on a small specimen from West Africa; 

 he discusses it with reference to depressa and alexandri but makes no mention 

 of ovata or richardi; I see no reason to doubt it was a young richardi. In 1893, 

 Alcock described a species from India, which he called castanea; unfortunately 

 he gives no measurements but I can find no valid character in his description 

 by which to distinguish it from ovata. In 1905, Doderlein described two species, 

 chuni and sumatrana, taken by the Valdivia, and related so nearly to crassa 

 that he called them Palaeolampas. The material was scanty and imperfect 

 and the status of the two species is still debatable. 



The primary character by which the species are to be distinguished is the 

 relative length of the various poriferous areas, but as this is affected by growth- 

 changes and subject to more or less individual variation, it has to be used with 

 caution. The shape of the test is a similarly useful character, but of variable 

 value, while the tuberculation of the test is rather more reliable. The dis- 

 tance separating the pore-pairs in an area from each other, and the distance 

 between the two pores of a pair are factors to be considered. But little weight 

 can be given to color and only in few cases do the pedicellariae prove of dis- 

 tinctive value. 



Key to the Species of Echinolampas. 



Poriferous areas abactinally, long, reaching nearly or quite to ambitus (at least in 

 posterior areas of ambulacra II and IV), with little or no tendency to form 

 petals. 



Test nearly as wide as long; ambulacra rather wide (half way between apex and 



ambitus, ambulacrum II is more than \ of interambulacrum 2, at same 



level); median area of II with 6 or more vertical series of primary tubercles. 



Test not gibbous posteriorly; anterior poriferous areas of ambulacra II 



and IV, only 4-10 pore-pairs shorter than posterior crassa. 



Test somewhat gibbous posteriorly; anterior poriferous areas of II and 



IV, 17-20 pore-pairs shorter than posterior sumatrana. 



Test not nearly as wide as long (width .80-. 86 of length); ambulacra narrow 

 (II not over J of 2); median area of II with only :; i vertical series of primary 



tubercles . • chuni. 



Poriferous areas abactinally more or less shortened, not reaching nearly to ambitus, 

 often distinctly petaloid. 



Ambulacra moderately wide, more or less petaloid abactinally ; inner poriferous 

 areas of ambulacra I and V muofa more than half as long as outer. 



