340 Mr. A. Hancock on the Excavating Powers of Sponges, 
generally small, numerous, disposed with a good deal of regu- 
larity, and having a few very much larger than the rest inter- 
mingled; the larger ones z';th of an inch in diameter. Spicula 
of two forms ; one ;4,th of an inch long, sometimes quite straight, 
but generally a little bent, particularly towards the end which 
is sharp-pointed ; from thence it gradually enlarges to the other 
extremity ; this terminates in a large, strongly defined, globular 
head, which is generally somewhat flattened like that of a pin; 
the shaft being mostly a little constricted at the point of union 
with the head. The other form of spiculum is only about 1th the 
length of the former, is irregularly tuberculated, and very stout 
and squat, bends rather suddenly in the centre, and tapers ab- 
ruptly to the ends which are obtusely pointed. 
This species is very like C. spinosa in general habit, but the 
terminal twigs are not so delicate, and are more regularly bifur- 
cated: the lobes too are larger, and the papille less than they 
are in that species. The spicula are also very different, and are 
quite sufficient to remove all doubt if such existed. 
Two or three specimens of C. cervina have occurred in the 
valves of Meleagrina albina? to which they have done much 
damage, and through the pellucid inner substance of which the 
sponge is distinctly revealed. These specimens are in the New- 
castle Museum. 
C. dendritica. Pl. XII. fig. 5. and PI. XV. fig. 4. 
Sponge minutely branched, slightly and irregularly anastomo- 
sing; the branches swelling at intervals into rounded or elon- 
gated lobes about 31th of an inch wide: terminal twigs fre- 
quently very long, and freely and elegantly divided like the 
branches of a tree: papille small, not numerous. Spicula not 
more than 75th of an inch long, proportionately stout, straight, 
occasionally a little bent ; one end with a globular head, some- 
times inclined to ovate, and tapering gradually to the other ex- 
tremity, which is very finely pointed ; there are likewise fusiform 
spicula; these are considerably smaller than those with heads, 
and bend suddenly in the centre; from thence they taper and 
terminate at each end in a sharp point. 
Several individuals of this pretty species have been observed 
in a specimen of Patella Mexicana in the Newcastle Museum. 
These are clearly seen through the pellucid enamel of the inside 
of the shell, and have a very distinct dendritic appearance. 
C. Canadensis. Pl. XIV. fig. 10. 
Sponge composed of a dense anastomosing mass of strongly 
lobed branches ; the lobes large in proportion to the central stem, 
but rarely exceeding ;/,th of an inch wide, somewhat rounded, 
