256 K. MITSUKUEI : STUDIES ON 



with a very fragmentary terminal plate or none at all, but devoid 

 of any other supporting rods than such as arc found in the body- 

 wall itself. Length of the largest specimen, 38 mm. Colour in 

 alcohol : I dorsal surface and the ends of the bod}--, dirty brown; 

 ventral surface, yellowish-grey. Possibly this species may be 

 nearly allied to Cucumaria nigricans.'' (Thkel). 



Remarls : — In one specimen (No. 1092), the body tapers about 

 equally towards both extremities. In the other it becomes much 

 more slender posteriorly than anteriorly. The first specimen is 

 curved in on the ventral side, and the second on the dorsal. The 

 former 3.8 cm. long and 1.7 cm. broad ; the latter 4 cm. long and 

 1.4cm. broad. Both of the same coloration, i.e., dark brown on 

 the dorsal surface and lighter brown on the ventral. In the first 

 specimen, there is a dark, nearly black, band along the dorsal 

 median lino. In the same specimen, I was able to demonstrate five 

 irregular anal plates made up of calcareous network ; they scarcely 

 deserve to be called teeth. Pedicels in two rows along each ambu- 

 lacrum ; also present in scattered distribution in all interambulacra. 

 In the second specimen, the pedicels assumed an irregularly two- 

 rowed arrangement in each interambulacrum. Polian vesicle and 

 stone- canal one each. Calcareous ring slender and very imperfectly 

 calcified. Respiratory trees present. 



Calcareous dejxjsits as described dy Theel. Most numerous 

 are the spcctacle-liko bodies, with a hole in each enlarged end. 

 The holes may increase in number and the form of the bodies 

 may become more irregular, finally transforming themselves into 

 irregular plates perforated by numerous holes. The bodies found 

 in the wall of pedicels are much more slender than those in other 

 parts of the body, though similar in other respects. Terminal 

 plates of pedicels rudimentary or wanting. 



