84 DR.J.S. BOWERBANK ON SILICEO-FIBROUS SPONGES. [Jan. 28, 
remaining of the basal membrane or true surface of attachment, and 
has in the centre of its present base a hole through it big enough to 
receive my first finger; and it is probable that the true base was an 
inch or more below the present one. On its external surface it has 
numerous wide and deep channels, radiating irregularly from the base 
towards the margin of the cup. The ridges between these channels 
have rounded edges, and they have frequently round or oval aper- 
tures irregularly dispersed upon them. Both channels and round 
orifices penetrate deeply into the substance of the sponge. The in- 
terior surface has very few of these interstitial channels; but there 
are an abundance of large cavities of a somewhat funnel-shaped form, 
their lower orifices being small compared with their surface ones, 
many of which are } inch in diameter. There is a very slight 
tendency towards a radial arrangement of these large orifices. 
The results of the microscopical examinations of fragments of 
the tissues of this sponge from various parts were exceedingly satis- 
factory. From the part of the base of the sponge, where it is stained 
yellow by the remains of the animal matter, I obtained portions of 
membranous structure containing numerous specimens of dichotomo- 
patento-ternate spicula, like those in the basal membrane of the type 
specimen in the British Museum. Dense patches of small acerate 
spicula with numerous minute simple attenuato-stellate ones inter- 
mixed with them, precisely similar to those in the type specimen, 
were also abundant and in situ, completely covering and concealing 
comparatively large fragments of the skeleton-tissues. A few frag- 
ments of a basal siliceous reticulation similar to that in the type spe- 
cimen were also observed. 
From a part of the external surface of the sponge near its upper 
margin, which was stained of a brown colour by the animal matter, I 
obtain fragments containing numerous patches of dark amber- 
coloured sarcode and a considerable number of gemmules in situ. 
They are globose and variable in size (Plate III. fig. 12); they 
are membranous and aspiculous, and are very like those figured in 
plate 25. fig. 340, ‘Monograph of British Spongiadee,’ vol. i., from 
Iphiteon panicea in the Museum of the Jardin des Plantes. Im- 
bedded in the patches of sarcode there were trifurcated attenuate 
and spinulo-trifurcated hexradiate stellate spicula in considerable 
quantities ; and in some dust shaken out of the inside of the sponge 
numerous fine specimens of the large fusiformi-acerate spicula, like 
those of the type specimens, were obtained. The discovery in the 
French specimen of the dichotomo-patento-ternate spicula, and the 
patches of the small acerate and simple attenuato-stellate spicula in- 
termingled, is highly satisfactory, as it places beyond a reasonable 
doubt their true positions in the sponge, and that they were not ad- 
ventitious in the type specimen, but were really characteristic of the 
species; and at the same time it marks the specific identity of the 
French specimen with the type one of Stutchbury’s genus. 
None of the large acerate or cylindrical verticillately spinous spi- 
cula which abound in the basal membrane of the type specimen, 
or of the subequiangular triradiate spicula of the dermal membrane, 
