with descriptions of new Species. 339 
collection I am indebted on this, as on a former 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. 
C. spinosa. PI. XIII. figs.5 & 7. 
Sponge branched, regularly anastomosing ; the branches along 
their entire course swelling into large lobes measuring nearly 
zoth of an inch wide: terminal twigs minute, tapering, having 
a spine-like appearance, generally simple, but frequently a little 
branched : papille numerous, for the most part small, with one 
here and there very much larger than the rest ; the largest about 
+;th of an inch in diameter. When the sponge is in a growing 
state, the papille 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 papille are pretty regularly distributed over the whole 
surface. Spicula of two kinds; one has a globular head at one 
end, is rather stout, straight, ~th 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 3rd 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 of 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 Neweastle : 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 +!,th of an inch 
wide: terminal branches or twigs rather stout, slightly tapering, 
bifureating pretty regularly, and frequently with lateral branches 
giving to them not a little the appearance of antlers: papille 
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