with descriptions of new Species. 339 



collection 1 am indebted on this, as on a fonner occasion, for 

 much valuable assistance. 



On account of the transparency of the shell the whole of the 

 sponge is exposed to view, as well as a series of the young exhi- 

 biting every stage of development. The walls of the chambers of 

 this species are strongly punctured. 



a spinosa. PI. XIII. figs. 5 & 7. 



Sponge branched, regularly anastomosing ; the branches along 

 their entire course swelling into large lobes measuring nearly 

 Y*2^th of an inch wide : terminal twigs minute, tapering, having 

 a spine-like appearance, generally simple, but frequently a little 

 branched : papillae numerous, for the most part small, with one 

 here and there very much larger than the rest ; the largest about 

 Y^2 th of an inch in diameter. When the sponge is in a growing 

 state, the papillae penetrate the surface of the matrix in single 

 rows in a somewhat branched manner, but as the growth matures 

 and the anastomosis goes on, this arrangement is lost ; and ulti- 

 mately the papillae are pretty regularly distributed over the whole 

 surface. Spicula of two kinds ; one has a globular head at one 

 end, is rather stout, straight, -^jth of an inch long, and tapers 

 gradually to the opposite extremity, where it terminates in a fine 

 sharp point : the other kind is fusiform, and is scarcely ^rd as 

 long as that with a head, and is much less stout ; it is bent sud- 

 denly in the middle, and from thence tapers gradually to the 

 ends, which are very sharp and a little recurved. 



Of this species I have seen at least four individuals in the 

 valves oi Perna femoralis and Placuna sella, and these I have been 

 able to examine with great facility, on account of the transparency 

 of the inner layer of shell through which the lobed branches with 

 their terminal twigs are most distinctly visible, the internal punc- 

 turing giving to them a pretty silvery appearance, and rendering 

 the whole under a lens an object of great beauty. In the Placuna, 

 which measures 6 inches wide, the ramifications of the sponge 

 have passed from side to side, and have done much damage to 

 the surface of both valves. For these specimens I am indebted 

 to Mr. Robert Currie of Newcastle : those in Perna, from which 

 the figures are taken, are in the Newcastle Museum. 



C. cervina. PL XV. fig. 8. 



Sponge formed of numerous branches, anastomosing, and en- 

 larged into many rounded, and sometimes elongated lobes which 

 are crowded upon each other, and measure each j^yth of an inch 

 wide : terminal branches or twigs rather stout, slightly tapering, 

 bifurcating pretty regularly, and frequently with lateral branches 

 giving to them not a little the appearance of antlers : papillae 



22* 



