30 AKT. 5. — SANJI HÔZAWA : 



The tiibar skeleton may be said to be on the whole of the 

 inarticulate type. It is chiefly composed of the basal rays of 

 subdermal pseudosagittal and subgastral sagittal triradiates. The 

 oppositely directed rays in question lie side by side almost in their 

 entire length. Usually the subdermal triradiates are less developed 

 than the subgastral. 



The gastral skeleton is much thinner than the dermal. It is 

 made up of the paired rays of subgastral sagittal triradiates, of 

 sagittal triradiates placed tangentially and with their basal rays 

 pointing towards sponge base, and of a few quadrh'adiates which 

 have their short apical ray projecting into the gastral cavity. 



The skeleton of oscular margin is, in full-grown individuals, 

 composed of oxea and of triradiates, both closely set. The former 

 are of two kinds : the one is similar to that found in dermal 

 cortex, while the other is very thin and hair-like. The oscular 

 triradiates, which are apparently differentiated from the gastral 

 triradiates, have very slender basal ray and the stouter paired 

 rays standing nearly at right angles to it. 



Spicules. 



Dermal triradiates (textfig. 6, a, h). — Slightly sagittal. All rays 

 of equal thickness, tapering fi-om base to sharp point. Basal ray 

 quite straight, 80-170 /^ long and 8-12 p. thick. Paired rays of 

 about the same length, almost straight, 60-100 ;" long and 8-12 /^ 

 thick. 



Subdermal triradiates (textfig. 6, c, d). — Pseudosagittal, stout, 

 all rays of different length but of nearly the same tliickness, not 

 quite smooth. Basal ray generally curved near base, gradually 

 and sharply pointed. Paired rays of different length and shape. 

 The longer ray is slightly shorter than the basal ray, almost 



