224 K. MITSUKURI : STUDIES ON 



Although this species is put by Ludwig in the genus Thycne, 

 it seems to^me that tlie presence of a sole and the resemblance 

 of its calcareous deposits to those of Colochims doliohtm, make it 

 desirable to retain it in the genus Colochims. 



LncvlUii : — Japan {\. Maeenzeller '81, Lampeet '85, Theel '8G) ; Gulf 

 of Tokyo. 



Genus Fsolus Oken 1815. 

 52. I*soliis (isci(lit'fo)'Uiis, sp. n. 



(PI. I , figs. 1.3—15 ; textfig. 41). 



Spcciinrn examhinh — One alcoholic specimen from off Miyako, Prov. of 

 Pukucliii, 500 him. Wakiya Coll., Feb. 1903. (Sp. Ko. 1G50). 



I can not identify this with any of the previously described 

 species. 



In alcohol, it is almost black in color. The shape is decided- 

 ly ascidian-like, both the oral and anal processes standing up 

 from the body more than 1 cm., the former being much larger 

 than the latter. The sole is trapezoidal in shape, the anterior 

 end being much broader than the posterior. There is no sign of 

 pedicels in the median ambulacrum. Around the margin of the 

 sole, there are two rows of pedicels, one within the projecting 

 rim of the sole, and the other just at the edge of the said rim. 



The whole dorsal surface not included in this sole is covered 

 with large scales. These are rather small around the edge of the 

 sole, but become larger towards the sides, the largest scales of the 

 body being found about half way up. They are without any 

 grains and are imbricated. I can not find any specially large 

 scales or any regular arrangement of them around the mouth or 

 anus. In alcohol, the surface shows corrugations. 



