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



oval, and occasionally irregularly augulated lobes about -[^^^ of 

 an inch wide, and united by a small central stem : terminal twigs 

 short, linear, and bifurcated : papillse small, numerous, and dis- 

 tributed on the surface of the matrix without apparent order. 

 Spicula yJo*^ ^^ ^^ ^^^^ l<^ng, not very slender, mostly a little 

 bent, and brought gradually to a sharp point at one end ; the 

 other with an irregularly rounded head, sometimes slightly ellip- 

 tical, and generally not exactly terminal. 



The puncturing of the chamber- walls of this species is strong 

 and decided, and the branches in old specimens are much con- 

 fused on account of the frequent anastomosis and the crowding 

 caused by the lobes. Towards the terminal twigs the character 

 of the branches is however quite distinct. The C. lohata is not 

 to be confounded with any other of the British forms, and is 

 undoubtedly distinct from the various foreign species that have 

 come under my notice. It occurs in Haliotis from Guernsey. 

 I have seen two specimens affected by it, and in both cases very 

 extensively ; in one the whole external surface is crowded with the 

 minute papillary punctures. 



C. vastifica, PI. XV. fig. 13. 



Sponge formed of a close and intricate anastomosis of strongly 

 lobed branches ; lobes irregularly angulated, frequently ^th of an 

 inch wide, and united by a delicate stem : terminal twigs not long, 

 linear : papillae small, rarely exceeding ^^^th of an inch in dia- 

 meter, very numerous, close-set, and pretty regularly distributed 

 over the surface of the matrix. Spicula of two kinds, one much 

 larger than the other; the former gV^^ ^^ ^^ ^^^ ^^ length, 

 straight, rather slender, and diminishing imperceptibly to a very 

 fine point at one end ; the other terminating in a perfectly glo- 

 bvdar head. The smaller kind of spiculum is about ^rd the 

 length of the larger, and is much thinner ; it is stoutish in the 

 centre, where it rather suddenly bends a little, and from thence 

 tapers gradually towards the ends, which are sharply pointed. 



When the outer surface of the shell containing this species is 

 removed, a complete close network of chambers is revealed, con- 

 taining the lobes of the sponge ; and on a closer examination they 

 are seen to be united by small circular passages for the accom- 

 modation of the uniting stems. The only specimen I have seen 

 of this species is in the shell of an oy^ster from Prestonpans ?, the 

 surface of which had suffered much injury by the influence of 

 this parasite. The puncturing of the sides of the cavities of this 

 species is finer than usual. 



C. rhombea. PI. XII. fig. 7. 

 Sponge when dry of a pale straw colour, composed of numc- 



