28 K. MITSUKUKI : STUDIES ON 



both opening separately l)ut close together into the cloaca and 

 extending to about the middle of the body. Their stem large, 

 branches short. 



Calcareous deposits consist, speaking in general terms, of 

 C-shaped bodies (textfig. (3 h, /,•) and cross-shaped tables [h — -/). 

 Of these there are various modifications in different parts {g, I, m). 

 In one specimen, the C-shaped bodies are very numerous (0.05 — ■ 

 0.09 mm. in long diani.). They lie at about the same level as the 

 cross-shaped bodies. In a second specimen, the C-shaped bodies 

 are scarce in the anterior parts, both ventral and dorsal, so that 

 their presence there was ascertained only after careful searching. 

 They are however rather numerous among the large X-shaped 

 bodies in the posteriormost parts of the ventral surface. In a 

 third specimen, C-shaped deposits are again very scarce, and 

 were found only after a most careful search. Even in this speci- 

 men, they are tolerably common among the large and thick 

 X-shaped spicules in the posteriormost ventral parts. There arc 

 a few C-sliaped bodies in the cloacal wall. — Cross- shaped tables 

 {b — cj) are somewhat scantily scattered in the perisome. They 

 seem most sensitive to the action of acid reagents. Both ventrally 

 and posteriorly they are of about the same size and shape. The 

 disk of the table consists of four arms, frequently of five {g). 

 The ends of two or more arms may be united. On the disk 

 is built a rather badly developed spire, with four pillars and 

 one or two cross-beams. Crown very irregular, with several 

 teeth, spreading out laterally. Both the disk and the spire 

 and crown present various degrees of imperfection. (3n the 

 whole, the anterior body parts, both ventral and dorsal, possess 

 tables smaller than those in the posterior parts. In the former 

 they are 0.05 — 0.084 mm. large, while in the latter the larger 



