288° DR. J.S. BOWERBANK ON THE SPONGIAD. _[ Apr. 6, 
description of both of these organs require the application of a 
power of at least 400 linear to render them distinctly to the eye. 
Their minuteness is such that they do not exceed in length the 
diameter of a skeleton-spiculum, +=,5 inch. 
The skeleton-rete is strongly developed, and the spicula are com- 
paratively short and very stout. 
The nearest alliance to this sponge among our British species is 
Halichondria forcipis. Its general habit, the forms and modes of 
disposition of the spicula of the dermis, and the form and propor- 
tions of the skeleton-spicula exhibit close resemblances ; but in other 
important characters the two species are essentially different. 
HA icHonpDRIA FRONDIFERA, Bowerbank. 
Sponge branching from the base numerously; branches rather 
compressed, frequently dividing, distal terminations spinoid. Sur- 
face minutely rugose. Oscula simple, minute, dispersed. Pores 
inconspicuous. Dermal membrane abundantly spiculous; tension- 
spicula acuate, rather long and slender, dispersed ; retentive spicula 
bidentate equianchorate, very minute and few in number. Skeleton- 
rete multispiculous, compact, rather close and strong, areas small ; 
spicula acuate, rather stout and short. Internal defensive spicula 
attenuato-acuate, entirely spined, short and stout, uniform in size, 
rather numerous. 
Colour, in the dried state, dull grey. 
Hab. Straits of Malacca and Gaspar Straits (Commodore Parish, 
R.N.). 
Examined in the dried state. 
I am indebted to my friend Commodore Parish for this remark- 
able sponge; he obtained it with many others from the Straits of 
Malacca. It is attached to the shell of a small Spondylus, nearly 
the whole of the valve of which is covered by the thin basal portion 
of the sponge, from which numerous slender compressed branches 
are given off, some of them nearly two inches in length; each of 
these branches resembles in form a stag’s horn, but with many more 
divisions than would be possessed by the horn. The oscula are 
simple and minute, a few only near the distal terminations of the 
branches being visible with the aid of a lens of two inches focus. 
The.tension-spicula of the dermal membrane are exceedingly nume- 
rous, so much so as almost to present a felted appearance ; they are 
quite as long as those of the skeleton, but not more than half their 
diameter. The bidentate equianchorate retentive spicula are very 
minute and slender, and very few in number: I could not detect 
them én situ; but amidst the spicula prepared by the action of nitric 
acid [ found them on some of the fragments of the dermal mem- 
brane and a very few among the other spicula; one of the largest of 
them measured 5;/5y inch in length. They require a power of 
about 400 linear to render them distinctly to the eye. The atten- 
uato-acuate, entirely spined, internal defensive spicula are uniform in 
size and rather numerous; they are based on the skeleton-rete, and 
