168 K. MITSUKUKI : STUDIES ON 



Its course is much convoluted. The madrejjoric body is pear- 

 shaped, situated opposite the opening in the mesentery facing the 

 middorsal interradius. Polian vesicle one, large, on the median 

 ventral ambulacrum. In one specimen, there was a second small 

 one on the left ventral interambulacrum. Calcareous I'ing, as in 

 many other Stichopus-speciGS, has the dorsal part pushed further 

 forward than the ventral part. Hence, all the pieces except the two on 

 the ventral and dorsal median linos are obliquely disposed. Selenka's 

 statements that the interradialia are broader than the radiaha has 

 been thought by v. Makenzeller to be incorrect, which opinion I 

 must share. Color varies greatly. I have seen two specimens (No. 

 1409) which are entirely white and must be considered as "albinos." 

 Again there are specimens which are of a deep, dark color ap- 

 proaching black without a single lighter spot. The most usual 

 colorations are as follows : Those that live among rocks along a 

 rocky beach have the dorsal surface of a variegated, mottled ap- 

 pearance with darker and lighter patches produced by the inter- 

 mingling of brown and maroon. The animal looks like rocks 

 overgrown or encrusted at spots with small algte and other marine 

 organisms, the coloration without doubt serving as a protection. 

 Individuals of this coloration seem moreover to have a larger 

 number of tall papillae. The ventral surface is of a red color 

 w^ith the tips of the tube-feet white. Those that live on sandy 

 or muddy ground, probably among sea-weeds, have generally a 

 uniform dark-green color, so much so that they are known in 

 common Japanese as " Ao-namako " (green holothurian). These 

 seem to have fewer and shorter papillas. 



The specimens from Hokkaido and the northernmost part of 

 Honshu have taller and more numerous papillae, which are most 

 conspicuous in dried specimens. In those specimens, the papillae 



