176 ARTHUR DENDT. 



skeleton. This sponge is solitary, and is remarkable for its 

 globular or subspherical shape, with correspondingly situated 

 gastral cavity and narrow osculum. The dermal cortex is 

 very strongly developed, occupying more than one third of the 

 entire thickness of the sponge wall. The inhalant pores, 

 scattered over the surface of the sponge, lead into wide, irregular 

 subdermal cavities lying in the cortex, from which inhalant 

 canals lead down between the radial chambers. The chambers 

 themselves are arranged parallel to one another with consider- 

 able regularity. They are long and narrow, and at their distal 

 ends they branch in a curiously irregular manner, the branches 

 sometimes penetrating for some little distance into the dermal 

 cortex. The proximal ends of the chambers are all situate at 

 about the same level, which is some little distance from the 

 gastral cavity, and even from the gastral cortex, which latter 

 is very much thinner than the dermal cortex. Hence we find 

 a number of rather short, cylindrical, radially arranged ex- 

 halant canals, which look exactly like continuations of the 

 radial chambers without the collared cells, and which may 

 unite together in groups before opening on the gastral surface. 

 The points of junction of these exhalant canals with the radial 

 chambers are marked as usual by diaphragms. The "inter- 

 canals " between the chambers are narrow and irregular. 



Ute spiculosa and U. Spenceri occupy a position in the 

 genus Ute very similar to that occupied by Grantia Vos- 

 maeri (fig. 10) in the genus Grantia. In both cases the typical 

 radial arrangement of the canal system is more or less dis- 

 turbed in accordance with the strong development of the 

 mesoderm and skeleton. 



Synute (fig. 15). 

 In this interesting sub-genus we meet with a very unusual, 

 if not unparalleled condition, in the complete fusion of a large 

 number of Syconoid individuals to form a compact, solid 

 sponge invested in a common cortex. The anatomy of Synute 

 pulchella, as seen in horizontal section, is represented in 

 fig. 15. As I have already pointed out (13), the canal system, 



