Recent and Fossil Hydractiniide. 299 
of an inch. In all there were thirty branches or processes, of 
which those at the extremities of the shell respectively were 
the largest and most subdivided. Spines and branches pre- 
senting the same kind of surface as that of the rest of the 
polypary, with the exception that the serrulated ridges of the 
granulated reticulation being longer, thus give rise to oblong 
or more or less elongated interstices; those on the spines 
forming a series of grano-serrulated ridges, diminishing in 
number upwards, until the last three or four, uniting into a 
point at the summit as in Hydractinia echinata, thus close 
the cancellated structure of which the spine is otherwise com- 
posed, Branches more or less divided and covered with small 
spines, which terminate the free ends in an alternate manner 
like those of Sertularia. Internal structure cancellous 
throughout and in direct continuity with the surface through 
the holes of the polypites, so that the ccenosare thus forms a 
continuous mass, in which the chitinous, clathrous polypary, 
having been developed, becomes its skeleton or organ of sup- 
ort, sometimes extending into the calcareous material of 
the shell itself, and transforming the whole lip, as in the pre- 
sent instance, into polypary (fig. 1, d). Size depending upon 
that of the object over which the Hydractinia may be grow- 
ing; in the present instance the shell covered by it is 21 
inches by # inch broad in its greatest diameters. 
Hab. Marine, growing over hard objects; in the present 
instance completely covering a shell like Phos senticosus or 
Fusus sulcatus. 
Loc. ? Polynesia. 
Obs. The specimen from which the above description has 
been taken now belongs to the British Museum, and was found, 
without any label or indication of its locality, among the late 
Dr. Bowerbank’s collections. Whether by the waves origi- 
nally, or subsequently from other causes, it has been lament- 
ably treated ; for at the present time, as above stated, out of 
the thirty short branches which it once possessed, not one 
now remains entire, the whole having been broken off at 
variable distances respectively from their origin in the Jami- 
niform portion, and some close to it; while the only branched 
one which is left projects laterally from that part of the poly- 
pary which once entzrely covered the apex of the shell as well 
as all other parts, but which is now broken away at this part, 
on the opposite side, so as to expose the apex of the shell 
itself, the only part consequently now uncovered (fig. 1, c). 
At first sight the specimen looks like a shell with branched 
spines ; but on closer inspection this is found to be a mistake, 
although the branches in some parts may have been initiated 
20* 
