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comparison betweeu type-slides of both. Tliose of S. raucronata I 

 owe to the kindness of Prof. Sollas from Dobliu. Sollas leaves 

 this question of indentity open ; but then , he has not seen S. 

 carbouaria. 



The sponge occurs iu the shape of irregular lumps. The surface 

 is very rough on the touch. The stomas are difficult to be seen ; 

 they are scattered irregularly and vary much in size. Generally 

 there is but oue proct. The colour is dark brown or black. 



A longitudiual section through a proct of the living sponge 

 exhibits a rather rough substance , sepia-brown with an olive 

 shade. Towards the periphery the colour grows darker, and this 

 dark baud simulates a cortex , but goes in fact a good deal deeper. 



The procts and ultimate excurrent canals are , compared with 

 the size of the sponge small. The stomas are the entrances of 

 much wider lacunae which, communicating with others , form quite 

 a lacunar system in the cortex. Under the cortex is a layer of 

 small crypts , from which narrow canals start; these debouch into 

 wide lacunae , from which the system of ramifying canals starts. 

 The skeleton of the cortex consits of three distinct parts: 1. one 

 or more layers of amphiasters, close under the outer pinacocytes. 

 2. a layer of small dichotriaenes and oxeas , the former placed at 

 right angles to the surface, the latter, in the region of the cla- 

 domes parallel to the surface (tangential) 3. Some layers of tan- 

 gential oxeas. Between these megascleres various modifications of 

 the aster are to be seen. 



The skeleton of the parenchyme consists chiefly of a dense mass 

 of oxeas , which , especially towards the periphery of the sponge 

 show a radial arrangement. Some oxeas from these radial bundies 

 pass through the cortex aud project, although but a little , beyond 

 the surface. Just under the cortex we find again a layer of di- 

 chotriaenes. Through the whole parenchyme numerous asters are 

 visible. 



Spicules. Oxea. Stout, sharp-pointed , fusiform, not quite 

 straight. 



Stylus. Not frequent; with transitions to tylostylus and strongylus. 



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