Knowledge of the Spongida. 323 
also like these, it has all the characters, except in spiculation, 
of Dr. Bowerbank’s British species of ‘‘ Dictyocylindrus,” 
modified. Sharp-pointed as the spicule is at both ends, the 
preponderance being on one side of the centre causes it to 
tend towards the acuate form, which is characteristic of the 
last species. There are two specimens of this sponge in the 
British Museum, which are both numbered ‘ 402,” but with- 
out register-number. 
Different again as the foregoing specimens may be from 
those with which we commenced this family, the following 
are so much more so in appearance that, until minutely ex- 
amined also, the fundamental composition and structure which 
determine their position cannot be satisfactorily observed. At 
first they look so much like specimens of Halichondria panicea 
that it is difficult to conceive that they do not belong to the 
same group or genus (which is the first in my order Holorha- 
phidota) on account of the massiveness of their structure, the 
characteristic whiteness of the dermal layer and the sponge- 
colour of the interior also being so similar ; but the delusion 
disappears as the structure and spiculation of the elementary 
portions of a typical species like the following are microscopi- 
cally examined, when the “ scopiform”’ filaments emanating 
from the condensed axial structure recall to mind those of 
Phycopsis fruticulosa, and there is also an echinating spicule, 
which here (although not in all the species belonging to this 
group) is acuate and not acerate ; still, as this is chiefly seen 
in the circumferential growths before they pass into the axial 
or general mass, it is necessary especially here to look for it 
at the commencing rather than in the subsequent development, 
wherein all such distinctions become merged in the general 
mass. 
Leucophleus massalis, n. gen. et sp. 
(Pl. XIV. fig. 15, a, 6.) 
Globo-conical, massive, surrounded towards the base with 
proliferous, erect, conical columns of variable size and length, 
entering as they grow into the increase of the central part. 
Consistence compact. Colour snow-white. Surface smooth, 
but irregular, being more or less rugose and furrowed verti- 
cally, pierced with minute puncta which now (in the dry 
state) indicate the position of the pores. Vents not seen. 
Internal structure concealed by a thick white crust, composed 
of the spicules of the species supported on a dense sponge- 
brown fibrous mass, partaking in compactness of the axial 
structure of the circumferential columns, which in their turn 
