340 Mr. A. Hancock on the Excavating Powers of Sponges, 



generally small, numerous, disposed with a good deal of regu- 

 larity, and having a few very much larger than the rest inter- 

 mingled ; the larger ones gV^^ ^^ ^^ ^^^^ ^^ diameter. Spicula 

 of two forms ; one y^oth of an inch long, sometimes quite straight, 

 but generally a little bent, particularly towards the end which 

 is sharp-pointed; from thence it gradually enlarges to the other 

 extremity ; this terminates in a large, strongly defined, globular 

 head, which is generally somewhat flattened like that of a pin ; 

 the shaft being mostly a little constricted at the point of union 

 with the head. The other form of spiculum is only about ^th the 

 length of the former, is irregularly tuberculated, and very stout 

 and squat, bends rather suddenly in the centre, and tapers ab- 

 ruptly to the ends which are obtusely pointed. 



This species is very like C. spinosa in general habit, but the 

 terminal twigs are not so delicate, and are more regularly bifur- 

 cated : the lobes too are larger, and the papillae less than they 

 are in that species. The spicula are also very different, and are 

 quite sufficient to remove all doubt if such existed. 



Two or three specimens of C. cervina have occurred in the 

 valves of Meleagrina albinat to which they have done much 

 damage, and through the pellucid inner substance of which the 

 sponge is distinctly revealed. These specimens are in the New- 

 castle Museum. 



C. dendritica. PI. XII. fig. 5. and PI. XV. fig. 4. 



Sponge minutely branched, slightly and irregularly anastomo- 

 sing ; the branches swelling at intervals into rounded or elon- 

 gated lobes about ^^^th of an inch wide : terminal twigs fre- 

 quently very long, and freely and elegantly divided like the 

 branches of a tree : papillae small, not numerous. Spicula not 

 more than yyjth of an inch long, proportionately stout, straight, 

 occasionally a little bent ; one end with a globular head, some- 

 times inclined to ovate, and tapering gradually to the other ex- 

 tremity, which is very finely pointed : there are likewise fusiform 

 spicula; these are considerably smaller than those with heads, 

 and bend suddenly in the centre ; from thence they taper and 

 terminate at each end in a sharp point. 



Several individuals of this pretty species have been observed 

 in a specimen of Patella Mexicana in the Newcastle Museum. 

 These are clearly seen through the pellucid enamel of the inside 

 of the shell, and have a very distinct dendritic appearance. 



C. Canadensis. PI. XIV. fig. 10. 



Sponge composed of a dense anastomosing mass of strongly 

 lobed branches ; the lobes large in proportion to the central stem, 

 but rarely exceeding y^th of an inch wide, somewhat rounded. 



