192 ART. 7. 1. IJIMA : HEXACTINELLTDA, IV. 



each two of the flaps there remains in the oscular edge an 

 unreflected point ; consequently there arises at each such position 

 an ear-like projection, which is all the more prominent since the 

 edge of reflection of the flaps on its either side is depressed so 

 as to present a concavity directed upwards. There are three 

 such ears in the fragment on hand, measuring 105-145 mm. 

 from tip to tip of two adjacent ears. In the entire state of the 

 individual there must have existed at least seven ears and as 

 many reflected flaps around the superior opening of the gastral 

 cavity. 



The w^all is 13 mm. tliick at a point ahout 100 mm. below 

 the tip of the ears and must liave been thicker towards the 

 sponge-base. 



The state of preservation of the specimen which has been 

 dried, is as good as could be desired. The dermal surface is 

 tolerably smooth, distinctly showing the delicate, regularly quadrate- 

 meshed dermal lacework and the irregularly meshed hypodermal 

 network. On close observation, the thin fillers composing the 

 latter are seen to be so arranged as to present numerous radial 

 figures, the centers of which are 2i-ß mm. apart from one another. 

 Pentactinic prostalia of medium size are found only on parts of 

 the external surface tliat are protected from abrading influences 

 by the folding of the marginal flaps. They are irregularly dis- 

 tributed, usually solitary and project to the length of at most 3 mm. 

 Except a few isolated and quite insignificant needle-like spicules 

 springing out on the sharp oscular edge, no diactinic prostalia 

 are present. Presumably, however, the species in a young stage 

 of growth is provided with a greater quantity of both pentactinic 

 and diactinic prostalia. 



The larger apertures of incurrent canals, vaguely visible 



