HALICHONDRIA. 121 



namara, which are never left dry but during the spring tides of 

 March and April : of rare occurrence, Wm. M'CoUa. 



Sponge forming an irregular thick crust cellular like crumb- 

 of-bread, harsh and firm to the feel, inelastic, friable when 

 dry, the sui-face latticed with angulated or sinuous pores, not 

 covered with a skin, but sometimes connected by a thin mem- 

 . brane formed by the drying of the gelatine : the oscula large, 

 scattered, raised into crater-like papillee perforated on the tops, 

 with the thin rim scarcely more compact than the other parts. 

 The boundaries of the pores are sinuous, rugous, and somewhat 

 hispid from^the projecting spicula. These are stout, short, 

 slightly curved and pointed at both ends. 



This so nearly resembles some varieties of H. incrustans that 

 the foiTTi of the spicula can alone discover their distinctness, ex- 

 cept the character derived from the oscula being papillary should 

 prove to be constant. I know no other species with which H. 

 saburrata can be confounded. 



18. H. AREOLATA, encrusthig, the surface even, latticed 

 toith angulated sphious cells ; oscidanonc; spicula feiv, rather 

 short, curved and douhle-pointed. 



Plate XIII. Fig. 4. 



Huh. On the under surface of stones at low water-mark. 

 Scarborough, Mr Bean. Dublin bay, A. H. Hassall. 



Sponge crustaceous, spi-eading irregularly, about one-eighth 

 of an inch in thickness, of a brown colour, the surface even, 

 honey-combed with large quadrangular or pentangular cells 

 bounded by a thread-hke line which, at every angle, forms a 

 small spinous point : fecal orifices none : structure somewhat 

 fibrous, and the fibres appear through a magnifier roughish as 

 if encrusted with grains of sand. Specimens in the cabinet are 

 rigid and friable, but when living the sponge contains a largo 



