E. MAESHALLI. — GEN. ARRANGEMENT OF SOFT PARTS. 127 



between the said evaginations in association with the straight 

 penetrating proximal rays of the dermalia. The said spicules 

 and tlieir bundles stand of course in connection with the trabecular 

 system of the region and leave open the external apertures as 

 well as the lumen of tlie incurrent canals, to which they partially 

 furnish an incomplete wall. 



On the other hand, the inner set of the choanosomal spicules 

 is comparatively very weakly developed, a fact corresponding to 

 the sparseness of the trabeculfe and the thinness of their layer 

 on that side. In the first place, the distal rays of the gastralia 

 and of the canalaria are neither so numerous nor so long as the 

 proximal rays of the dermalia on the outside. Further, the 

 parenchymalia of the inner set, which in part go to supplement 

 the gastralia and the canalaria in supporting the respective lining 

 membranes, are decidedly not numerous ; they are moreover all 

 thin and if grouped at all, appear at the most in thin loose 

 strands. 



All the soft parts alluded to in the above account are found 

 in the cuff, in the sieve-plate beams and in the bottom-plate in 

 essentially the same arrangement as in the lateral wall. I 

 emphasize this fact, because it clearly manifests the identical 

 nature of the body-parts just mentioned and furthermore serves 

 to give basis for regarding all the large gaps in the lateral wall, 

 in the sieve-plate and in the bottom-plate alike as oscula (see 

 pp. 38, 39, 94). 



To follow, by way of a resume, the course of water in its 

 passage through the sponge-wall : Through the pores of the 

 dermal membrane and the intertrabecular lacunte of the ectosome, 

 it enters into the subdermal cavity. Here it almost directly bathes 



