324 DR. J.S. BOWERBANK ON SILICEO-FIBROUS SPONGES. [May 13, 
IPpHITEON PANICEA, Valenciennes. 
Sponge cyathiform, slightly pedicelled. Surface of rigid skeleton 
even? Oscula, pores, and dermal membrane unknown. Skeleton 
symmetrically radial ; radii short and stout ; areas of the rete mostly 
six-sided, spaces within triangular; fibre cylindrical, incipiently 
spinous. Tension-spicula simple, hexradiate, slender, abundantly 
spinous; radii terminally more or less clavate. Retentive spicula 
spinulo-pentafurcated? hexradiate stellate, few in number. Gem- 
mules simple, membranous, subspherical, irregularly dispersed, very 
numerous. 
Colour in the living state unknown. 
Hab. Porto Rico, 1799 (Prof. Valenciennes). 
Examined in the state of skeleton. 
The specimen designated Iphiteon panicea in the Museum of the 
Jardin des Plantes, Paris, is said to have been brought from Porto 
Rico in the year 1799. It is an irregularly cup-shaped sponge, the 
diameter of its distal margin being about equal to its height, which, 
to the best of my recollection, was from 7 to 8 inches. From the 
colour and general appearance of the specimen, I believe it to be the 
one from which Prof. Valenciennes gave a small fragment to Prof. 
Melville some years since, which he kindly transferred to me, and 
which fragment contains the gemmules in situ. I have so fully de- 
scribed the general structure of the skeleton in my description of the 
genus, as to render it unnecessary to dilate further on that portion 
of its history. 
No fragments of the expansile dermal system could be detected ; 
and we are therefore deprived of the most important specific cha- 
racters. 
I could not detect auxiliary skeleton-spicula, simulating hexradiate 
spicula, springing from the primary skeleton-fibres and anastomo- 
sing freely with each other, as in Dactylocalyz ; but in lieu of them 
true simple hexradiate tension-spicula were frequently to be seen in 
groups in the interstitial spaces, but they never appeared to inoscu- 
late with each other or to deviate from their normal forms. These 
spicula are of comparatively large size; the radii are slightly and 
progressively attenuated, and entirely and acutely spinous, but they 
do not terminate in a point, but either in a group of acute spines or 
they are more or less subclavate. 
The retentive spicula appear to be exceedingly few in number in 
the interstitial tissues; in several small masses of the skeleton 
abounding in sarcode and gemmules I found but two of them. The 
secondary radii were apparently five in number, but they were so 
much obscured by the surrounding sarcode as to render the deter- 
mination of this character very uncertain. 
The simple membranous subspherical gemmules are very like 
those of a halichondroid sponge; they are very numerous, some- 
what variable in size and form, and are nearly all of them attached 
to the skeleton-fibres. 
A portion of the skeleton with the gemmules is figured in the 
