76 K. MixsuKUiii : STUDIES ox 



liemarks : — All tho speeimous arc small, the largest being 

 about 5.5 X 1.5 cm. in alcohol. They are all uniformly brown- 

 colored. Dorsal papillae are somewhat thinly scattered, but in 

 some specimens they seem to stand in a double row on each of 

 the dorsal ambulacra. They are placed on conical warts. Ventral 

 pedicels are much more crowded, but in many specimens, they 

 can bo made out to be arranged in three longitudinal zones. 

 Reproductive organs on the left side only ; so far as dissected, 

 they consisted of simple unbranched tubes. This was no doubt 

 due to the immature condition of the specimens. Polian vesicles 

 two on the ventral side. Stone-canal single, attached to the 

 dorsal mesentery, small but comparatively thick. Cuvierian 

 organ i)resent, attaclied to the lower part of the respiratory tree, 

 and coiled into an oval mass in alcohol. Calcareous ring small. 



Tables among calcareous deposits are large with largo per- 

 ipheral holes. Buttons plump, smooth-edged. Some with three 

 pairs of holes ; those with four, five or more holes are compara- 

 tively numerous in at least one of the rows. The two sides very 

 often differ in the number of holes. 



I believe that //. dijidlis and //. captira ought to be made 

 into a single species. In fact my specimens agree in some 

 respects better with the descriptions of //. captiva. For instance, 

 the attached stone-canal as stated I)y Ludwig and the rows of 

 tube-feet as stated by Bedford, are all found in ray specimens, 

 while I can not ascertain how they are arranged in 11. difficiUs. 

 The reason why I have assigned the name of IL dif kills to ray 

 specimens is : 1) because this name has priority, 2) because 

 //. captiva has been reported hitherto from the Atlantic only, 

 while H. dlfficilis is i-eported only from the Indo-Pacific. With a 

 little more reserve, I think that //. farcimen Selenka ought to bo 



