150 



UNITED STATES NATIONAL MUSEUM BULLETIN 251 



72. Chelyosoma siboja Oka 



Figure 58 



Chelyosoma siboja Oka, 1906b, p. 51.— Oka, 1935, p. 460, fig. 30. 



MATERIAL EXAMINED 



Japan: Hokkaido Island, Otaru ; E. S. Morse, coll. One specimen (USNM 

 11690). 



Description. — A single specimen was found in the material. It is 

 50 mm. by 38 mm. in extent, 24 mm. in height, and the siphonal area 

 is 34 mm. by 30 mm. in extent. Animal is attached to substratum 

 somewhat obliquely as shown in lateral view (fig. 586), which is given 

 rather schematically. Test thick, cartilaginous, brownish; surface 

 covered with bryozoans and small algae on some parts. Siphonal area 

 bears 31 plates in all : 23 marginal plates, 2 central plates, 3 intermedi- 

 ate plates on each side. Body surface other than siphonal area is 

 wrinlfled or very irregularly grooved. 



Figure 58. — Chelyosoma siboja Oka: a, apical side of the specimen; b, lateral side. 



