42 ART. h T. IJIMA : HEXACTINELLIDA, III. 



The flagellated chambers are cup-like or thimble-like. The 

 more elongated chambers occur in the periphery of the choano- 

 some. The flagella are not preserved in mv preparations. The 

 chamber-wall consists of the usual membrana reticularis, the open 

 meshes of which may measure 7^^ /^ or less across. At places, a 

 pale ill-defined nucleus may be defined toleraldy constantly at 

 every nodal point of the reticulum. 



The larva (PI. III., figs. 23-25). — As announced in my 

 Contribution I. (pp. 182, 187), Leucopmcus oriliodocus is one of 

 the two Hexactinellid species in which I have discovered devel- 

 opmental stages of larvse, or at any rate of certain reproductive 

 bodies which may reasonably be interpreted as such, — the other 

 species being VitrolluJa fertile, a Eossellid to be described in 

 full iu a future Contribution. It was in only 8p. No. 230 of 

 the above mentionod Leucopsacid that I have found the said 

 reproductive bodies. These had to be searched for in sections 

 of the sponge and were by no means so numerous, nor so favorably 

 conditioned for observation, as was desirable ; hence, the frag- 

 mentary nature of the account given below. 



As before indicated, there exist, in liotli the sj)ecimens 

 examined, variously sized archœocyte-congeries (PI. III., fig. 22) 

 between the chambers or in the narrow spaces between the eva- 

 ginations of the chamber-layer. To judge from appearances, they 

 grow in size by multiplication of the compactly crowded cells. 

 A large congeries is spherical or approximately so and may 

 be nearly or quite as large as the body, shown in PI. III., 

 fig. 23 and which I consider as the larva in an early stage of 

 development. 



The larva in this stage is spherical, measuring about 57 /^ in 



