238 APPENDIX. 



an inch long, slender, generally bent in the centre, 

 tapering gradually to a sharp point at one end, and at 

 the other furnished with a well-defined elliptical head : 

 the second acerate, scarcely one-third the length of 

 the first, very delicate, and suddenly bent in the 

 centre, and when observed with the one-sixth inch 

 object glass is seen to be minutely spined; the 

 extremities are sharply pointed : the third is minute, 

 g-woth of an inch long, spinous, with obtuse extremities 

 and generally zigzagged, having three angles, one being 

 in the centre. 



In shells of Pert on maximus, Guernsey, &c. 



6. CLIOXA GRACILIS, Hancock. 



Cliona gracilis, Hancock. L. c., vol. iii, p. 334, pL xiv, fig. 7 ; 

 vol. xix, p. 10, pi. vii, fig. 4. 



Spicula of three kinds, the first spinulate, -^-th of 

 an inch long, generally a little bent, stout, and inclin- 

 ing to fusiform, with the pointed end gradually taper- 

 ing ; head rounded, somewhat elliptical, and merging 

 imperceptibly into the shaft : the second acerate, 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 is about TWo^ 1 

 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. 



In a shell of Pecten maximus probably from Orkney. 



