120 CLARK. 



noticed in this particular, though it was not so marked as in the 

 matter of color. My observations on the genital organs do not 

 accord with those of Professor Heilprin for I was unable to see 

 that the " filamental processes " are to any important degree 

 finer in one form than in the other ; what slight difference there 

 was seemed to me indicated that the filaments were coarser and 

 less numerous in the spotted form. Finally, regarding the 

 number of tentacles, my specimens from Bermuda differ from 

 Professor Heilprin's. Both those examined last year and four of 

 the five spotted ones in this year's collection have twenty tenta- 

 cles, the remaining one having nineteen. Each of the black 

 ones has twenty. Apparently the specimens examined by Pro- 

 fessor Heilprin and the specimen collected at Bermuda^ by the 

 " Challenger " were exceptional. I have tried in vain to find 

 some characteristic in the calcareous particles of the body wall 

 or in the calcareous ring, which would serve to distinguish the 

 two forms, but entirely without success. I have not found the 

 larger tables which Theel found in his specimen of vi'dbii from 

 Bermuda, though it would be absurd to say that there are none 

 present. The calcareous ring varies more or less in different 

 individuals but where best developed, it is markedly asymme- 

 trical (as Theel described it in S. japonicus) ^ that is the dorsal 

 pieces are much stouter than the ventral, and the dorsal radial 

 pieces have posterior prolongations. Both Professor Heilprin 

 and Mr. Carpenter say that the spotted form is somewhat smaller 

 and very much more scarce. Mr. Carpenter says of the two 

 forms : " The large black holothurian {SticJiopiis diadoli) is ex- 

 ceedingly abundant in the water of Castle Harbor and Harring- 

 ton Sound and along the outer shores of the island, within the 

 reef Wherever the white, sandy bottom, which is sometimes 

 more or less overgrown with seaweed, can be seen, there 

 SticJwptis is sure to be detected. The large spotted form is 

 much more rare. Living under the -Same general conditions 

 alongside of the uniformly black SticJiopiis, its occurrence is to 

 that of the latter, roughly as i to 60." The abov^e facts seem 

 to show that the only real difference between the two forms is 

 in the color, and it would be a cause of some surprise if inter- 



