176 ART. 7. — I. IJIMA : HEXACTINELLTDA, lY. 



A number of thin and isolated diactinic prostalia project at 

 low angles from the lateral surface, and are directed obliquely 

 upwards. They are generally 16 mm. or more in length. Close 

 to the thin oscular edge they are more numerous than elsewhere 

 but shoi'ter, projecting straight upwards to a length generally 

 under 3 mm. Here and there, especially near the oscular margin, 

 some pentactinic prostalia are also found. These are not large 

 nor numerous ; they project to the extent of at most 1 mm. 

 l)eyond the dermal surface. The latter is rather uneven, thouo-li 

 no conical or papilla-like elevations exist. 



The endosomal layer appears closely adherent to tlio choano- 

 somal mass, which fact is undoulitedly greatly due to the smallness 

 of the incurrent canals. The dermal lacework is but indistinctly 

 visible even when observed under the lens. Beneath it are seen 

 thin hypodermal fibers, — mostly the paratangentials of hypodermal 

 pentactins, — intersecting one another in an indefinite way, while 

 in places they converge towards several central points. 



The incurrent canalar apertures are not larger than about 

 1 mm. across. On the gastral surface, the very small apertures 

 of excurrent canals are of a roundish or irregular shajie, measuring 

 about h mm. in average diameter. They open close together, 

 without being covered over by a special endosomal latticework. 

 The entire gastral surface, when looked at horizontally, presents 

 a finely and somewhat uniformly hairy appearance. This is 

 caused l)y the tiichodal ends of numerous parenchymal diactins 

 freely protruding beyond the surfoce to the length of about half 

 a millimeter or more. 



Macroscopically the sponge may l)e said to be but slightly 

 different in appearance from S. dowlingi, except perhaps in its 



