340 WILSON. [Vol. IX. 



directly with the afferent canals on the one side and the 

 efferent canals on the other, as may be gathered from PI. 

 XXII, Fig. 98, representing a small portion of the mesoderm of 

 the sponge. Efferent canals are abundant round the edge of 

 the spongy regions (Figs. 95 and 97), and communicate with 

 the larger efferent canals lying in the heart of the gelatinous 

 tissue. In the body of the sponge the main efferent canals 

 pursue an irregular course, but in the oscular papillae they run 

 longitudinally, there being at the base of the papilla several 

 which gradually run into one another as they near the summit 

 of the papilla. There is usually one canal in the axis of the 

 papilla, which is larger than the rest and may be considered 

 the main canal of the papilla. 



The gelatinous tissue is much like that of Tedania, consist- 

 ing of a network of cells with a watery jelly in the meshes. 

 As in Tedania, there is an abundance of delicate bipolar cells, 

 the processes of which are long, slender, and branching. There 

 are also numerous large granular cells, not present in Tedania. 

 PI. XXIII, Fig. 99, is a small portion of a section showing the 

 gelatinous tissue lying between two canals (f.w. = canal wall). 



The general arrangement of the skeleton is shown in PI. 

 XXII, Fig. 97. The brushes of spicules supporting the dermal 

 membrane, the radial and tangential bundles, and the distribu- 

 tion of the free spicules, need no further description. Where the 

 gelatinous tissue comes to the surface, the brushes of spicules 

 supporting the dermal membrane are either absent, or feebly 

 developed. The skeletogenous oxea is very often found with its 

 two ends modified after the fashion shown in PL XXII, Fig. 

 loi. The length of the process jr varies considerably. What 

 few tylotes occur are found either in the dermal membrane or in 

 the brushes supporting it. I have seen three or four tylotes 

 with nicked heads like those of Tedania. As in Tedania, the 

 microscleres are most abundant round the walls of the efferent 

 canals, but while they are larger than the microscleres of 

 Tedania, they are much less numerous. It may be mentioned 

 that after hunting persistently through many sections and 

 caustic potash preparations of this sponge, I have found four 

 anchors, varying in size but otherwise alike. Being unable to 



