256 I. TJIMA : IIEXACTINELLIDA. T. 



work is marked by a minute white spot, which under the micros- 

 cope proves to be a fioricome borne on the tip of the distal ray 

 of each dermalia. The meshes are seen to be overspread with a 

 cribellate dermal membrane. 



Through the dermal latticework are distinctly visible the 

 roundish or somewhat irregular-shaped apertures of the incur- 

 vent canaU, which are of various sizes under 2 mm. diameter 

 and are alwa3'^s rather shallow in conformity with the thinness of 

 the sponge- wall. Between the said apertures the dermal lattice- 

 work is in close contact with the parenchymal mass below. 



Amongst the latter, the trend of the coarser and more 

 peripherally situated jiarenchymal bundles is traceable from the 

 outside with sufficient distinctness. Arising from the compact 

 base of the sponge, they run irregularly upwards in oppositely 

 oblique directions, branching and uniting and loosely interweaving 

 with one another without regularity. In places the bundles are 

 fully 1 mm. thick ; more usually they are much thinner. 



The gastral surface (PI. IX, fig. 2) is devoid of a covering- 

 latticework. The parietal oscula are seen on this side to occupy 

 each a more or less depressed position, their iris-like membrane 

 lying on a level with the general external surface of the wall. 

 For the rest the gastral surface shows an uneven ness, firstly on 

 account of numerous roundish excurrent apertures, and secondly, 

 because of the most internally situated, coarse, parenchymal 

 bundles which project in a ridge-like manner. 



Close to a parietal osculum, the excurrent canals are but ver}' 

 small and shallow depressions. Farther away from it, they are 

 much larger, often having a diameter of 2 or o mm. While 

 some are pit-like thougli never ver}" deep, others are flat de- 



