282 DR. J. S: BOWERBANK ON THE SPONGIAD#. __[ Apr. 6, 
surface is entirely composed of tuberous projections, the surfaces of 
which are minutely corrugated. They vary from a 7 to 3 an inch in 
height, and in diameter from 2 to 4 or 5 lines. Their distal termi- 
nations are slightly convex or nearly flat, with a simple orifice 
frequently on the summit, and when in this condition they are more 
or less fistulous. The oscula are simple perforations, seldom exceed- 
ing the size of one of the skeleton-areas. 'The dermal membrane is 
pellucid. Itis rather sparingly furnished with slender acuate tension- 
spicula, which are of the same form as those of the skeleton columns, 
but rather shorter and more slender; and intermixed with the 
tension-spicula there are numerous minute grains of sand and other 
extraneous matters adherent to the outer surface of the membrane. 
The skeleton in this species is more complicated in its structure 
than it is in the greater number of the known species of the genus, 
the skeleton-columns anastomosing more frequently and more 
regularly than is usual; so that the skeleton assumes the form of a 
rudely constructed reticulation. The skeleton-columns are stout 
and strong, abounding in keratode, in which their long, slender, acuate 
spicula are somewhat loosely distributed ; and along with them there 
are frequently minute grains of extraneous matter imbedded. The 
columns are abundantly supplied with internal defensive, attenuato- 
acuate, entirely spined spicula; they are projected at nearly equal 
distances and at right angles to the surface into the interstitial spaces, 
so as to present an exceedingly formidable series of weapons of de- 
fence against the attacks of any intrusive annelids or other enemies. 
These defensive spicula require a linear power of about 300 to 
render their forms and spination distinctly to the eye. 
The interstitial membranes are furnished with a few tension-spicula 
and extraneous grains of sand in a manner very similar to that of 
the dermal membrane. The spicula of this species have their 
nearest alliance in form to those of our British species M. fallaz ; 
but the structural characters of the sponge in other respects are 
very strikingly different. 
In the spicula prepared by boiling in nitric acid and mounting in 
Canada balsam there were numerous adventitious forms of spicula, 
which the peculiarities of the structure of this sponge is especially 
liable to collect and retain; but of these very few, comparatively, 
could be detected on the insterstitial membranes of the sponge. 
HyMERAPHIA SPINULARIA, Bowerbank. 
Sponge coating, very thin. Surface even, strongly hispid. Oscula 
simple, minute, dispersed. Pores inconspicuous. Dermal membrane 
pellucid, sparingly spiculous ; spicula same as those of the skeleton. 
Skeleton and external defensive spicula subfusiformi-spinulate, 
long and rather slender, very numerous. Internal defensive spicula 
subfusiformi-spinulate, comparatively short and stout, numerous. 
Colour, in the dried state, light ochreous yellow. 
Hab. Coast of Corea (Commodore Parish, R.N.). 
Examined in the dried state. 
