1875.] DR. J. S. BOWERBANK ON THE SPONGIADS. 287 
HALICHONDRIA ASPERA, Bowerbank. 
Sponge massive, sessile; surface uneven and very rugged. Oscula 
simple, large and numerous, dispersed. Dermal membrane pellucid, 
abundantly spiculous; tension-spicula biclavate cylindrical, loosely 
fasciculated; and long and slender acerate,. dispersed; retentive 
spicula bidentate equianchorate, stout and comparatively large, few 
in number; and the same form very minute and rather numerous ; 
also bihamate, comparatively large and strong, few in number; and 
the same-form very minute and slender and much more numerous. 
Skeleton-rete more or less multispiculous, rather regular; spicula 
short and stout, acuate, occasionally subflecto-acuate. Interstitial 
membranes sparingly furnished with the same tension- and retentive 
spicula as the dermal membrane. 
Colour, in the dried state, pallid green. 
Hab. Straits of Malacca (Commodore Parish). 
Examined in the dried state. 
I received this sponge among others from my friend Commodore 
Parish, who obtained it from the Straits of Malacca. It is 23 
inches long by 2 in breadth; and the thickness is rather more than 
an inch. Its form is very irregular, and its surface exceedingly 
rugged and uneven, abounding in minute ridges and asperities, so 
much so that it is difficult at the first sight to distinguish the oscula. 
The dermal membrane is abundantly furnished with spicula. There 
are two distinct forms of the tension ones; the most abundant of 
the two are the biclavated cylindrical ones, which are usually gathered 
together in loosely formed fasciculi of from two or three to six or 
eight ; and a few of them are dispersed singly among: the others. 
The fasciculi are disposed without any approximation to order. 
The second form of tension-spiculum is very slender acerate or 
fusiformi-acerate; they are longer than the biclavated cylindrical 
ones, but less in their greatest diameter, and they are distributed 
singly in considerable number among the others. The occurrence 
of two distinct forms of tension-spicula and two different modes of 
their distribution is very rarely seen in the dermal membrane of the 
same sponge, and thus it is very characteristic of the species. The 
retentive spicula are also very remarkable in this species. There 
are two distinct sorts of bidentate equianchorate ones, and also of 
bihamate spicula. The largest sort of bidentate equianchorate ones 
are more than twice the size of the smaller anchorate ones ; compara- 
tively they are stout and strong; but they are very few in number, 
while the smaller ones are comparatively numerous. A full-sized 
large one measured +155 inch in length, while the average length of 
smaller ones was /;y inch in length. The same difference in size 
exists between the two sorts of bihamate spicula. The largest sort 
measured 71, inch in length, while two of the smaller ones measured 
respectively +1,, and ;,';5 inch in length. They are also compara- 
tively very numerous, while the larger ones are of very rare occur- 
rence. No gradational sizes exist between the large and small 
forms of either the anchorate or bihamate spicula. The small 
