1875. ] DR. J. S. BOWERBANK ON THE SPONGIADE, 291 
linear to define their forms distinctly ; proportionately they were 
rather stoutly and strongly formed. 
The structural peculiarities of the skeleton form a very striking 
specific character in this species. The rete is strongly and compactly 
formed, and the number of spicula in any part of it is far greater 
than can be counted. The areas are unsymmetrical and rather 
variable ; and the interstitial membranes filling them are frequently 
abundantly supplied with the same description of spicula as those of 
the dermal one. 
HALICHONDRIA COMPRESSA, Bowerbank. 
Sponge branching irregularly and abruptly ; branches compressed. 
Surface more or less rugose or spinous. Oscula simple, dispersed. 
Pores inconspicuous. Dermal membrane spiculous ; tension-spicula 
subclavate acuate, variable in form, dispersed or more or less fasci- 
culated ; retentive spicula bidentate, rarely tridentate equianchorate, 
comparatively large and very stout, rather few in number ; and the 
same form minute and slender, numerous. Skeleton-rete multi- 
spiculous, very irregular; areas large and variable in form ; spicula 
acuate, rather short and stout. Interstitial membranes sparingly 
spiculous; spicula same as those of the dermis. 
Colour, in the dried state, dark green. 
Hab. Straits of Malacca (Commodore Parish, R.N.). 
Examined in the dried state. 
I received this remarkable sponge with others from my friend 
Commodore Parish, who obtained it from the Straits of Malacca. It 
is rather less than 2 inches in height, and less than an inch wide at its 
greatest expansion. The external form is remarkably singular. It 
rises from a very small base, and immediately branches abruptly in 
every direction and at every possible angle. The branches are 
nearly all of the same size, and are all more or less compressed, and 
their surfaces rough and irregular. 
The dermal membrane is comparatively stout, and in most parts it 
is abundautly spiculous. The tension-spicula are occasionally sub- 
fasciculated, or so numerous as almost to appear felted together ; 
while in others they are dispersed singly, and rather sparingly 
distributed, crossing each other at various angles. These spicula are 
subject to considerable variation in form: all of them are more or 
less subclavate at the base, but their shafts exhibit the greatest 
amount of variation ; some are quite attenuato-acuate, while others 
terminate so obtusely as to closely approach the cylindrical form ; 
and gradational forms between the two extremes are of frequent 
occurrence. ‘lhe bidentate equianchorate retentive spicula also 
exhibit very remarkable characters. There are two very distinct 
sorts of them—one comparatively large and of very robust struc- 
ture, the other very minutely slender and delicate; both have their 
shafts semicircular. The larger ones average ;}y inch in length, 
with a diameter of shaft of ,);5 inch; the smaller series never 
appear to exceed ;34,5 inch in length, and the shaft fee of the 
19 
