THE EXCAVATING SPONGES. 349 



of Wight, a specimen of this species in a valve of Pecten maxi- 

 mus. The dried sponge is of a brown colour. 



C. gracilis. PL XVI, fig. 4. 



Spicula of three kinds : the first pin-like, about - 7 Vth of an 

 inch long, generally a little bent, stout, and inclining to fusi- 

 form, with the pointed end gradually tapering ; head rounded, 

 somewhat elliptical, and merging imperceptibly into the shaft : 

 the second kind is fusiform, one-third the length of the first, less 

 stout, and gradually bent in the centre, it is minutely spined, 

 and has the extremities sharply pointed : the third form is about 

 two th of an inch long, and is usually zigzagged so as to form four 

 or five angles ; it is most minutely spined, and has the extremities 

 rounded and recurved. 



When dry the sponge is of a yellowish-brown colour. 



C. Howsei. PL XVI, fig. 5. 



Spicula of three kinds : the first pin-like, about xo"oth of an 

 inch long, very delicate, generally straight, with the head broadly 

 ovate, short, well marked, terminal, and having the narrow end 

 at the extremity, and sometimes a little prolonged : the second 

 form is abundant and generally somewhat longer than the first, 

 equally slender and mostly slightly bent, and gradually dimin- 

 ishes to a fine point at one extremity ; the other has usually 

 two heads, one terminal or nearly so, the second about one-third 

 down the shaft ; the terminal head is frequently wanting : the 

 third form is about -^oth of an inch long, rather stout, cylindrical, 

 usually irregularly bent or angulated, and strongly spined, ivith 

 the extremities obtuse. 



A few additional specimens have occurred on the Northumber- 

 land coast. The sponge when dry is of a pale yellow-ochre 

 colour. 



C. Alderi. 



Spicula of two kinds : the first pin-like, T r eth of an inch long, 

 moderately thick, slightly bent, with a small head near one end, 

 and tapering to the other extremity : the second form is scarcely 



