1869.] DR. J. S. BOWERBANK ON SILICEO-FIBROUS SPONGES. 323 
6. A Monograph of the Siliceo-fibrous Sponges. 
By J. S. Bowrersank, LL.D., F.R.S., F.Z.S., &e.—Part I1.* 
(Plates XXI.-XXV.) 
Ipuitrron, Valenciennes. 
Iphiteon panicea, of the Museum, Jardin des Plantes, is distinctly 
a symmetrical structure. The skeleton is reticulated in a very remark- 
able manner. The whole consists of a series of regular areas, with 
pentagonal or hexagonal margins, from each angle of which a fibre 
passes in a direct line to the centre of the area, where they unite, 
forming a central, slightly protuberant mass. From each of these 
centres one or two fibres are given off at about right angles to the 
plane of the area, in opposite directions to each other, by which the 
adjoining areas above and below are connected. These connecting 
fibres always terminate at junctional angles of the nearest adjoining 
area, and the fibres thus projected never seem to unite with any 
other portions of the reticulating skeleton. 
The appearance resulting from this mode of structure is very re- 
markable when we view a microscopical plane of this beautiful tissue. 
The effect is that all the areas present a singularly confluent appear- 
ance, each perfect in itself, and each forming, as it were, a part of a 
neighbouring area. Occasionally square spaces may be found; but 
these are only intervals of the reticulations. 
In treating of the gemmules in my paper “On the Anatomy and 
Physiology of the Spongiade,” I have figured a small portion of the 
skeleton of the specimen in the French Museum, said to be from 
Porto Rico (plate 34. fig. 17, Phil. Trans. for 1862), and I 
have there designated it as identical with Stutchbury’s genus Dacty- 
localyx ; but a more critical examination, with a view to the deter- 
mination of its specific characters, has convinced me that I was in 
error in doing so, Neither Dactylocalyx nor Iphiteon appear in 
Lamarck’s ‘ Animaux sans Vertébres,’ second edition, published in 
1836, nor in Agassiz’s ‘ Nomenclator Zoologicus,’ published in 1848. 
Nor is there any notice of the subject in the list of the works of Prof. 
Valenciennes published in the ‘ Bibliographia Zoologize et Geologie,’ 
by the Ray Society, 1854; we may therefore reasonably conclude 
that although named by Prof. Valenciennes in the Museum of the 
Jardin des Plantes, he never published any descriptive characters of 
the genus. The symmetrical arrangement of the skeleton-structures 
distinctly separates Iphiteon from Dactylocalyx, with which it has 
hitherto been confounded by other English naturalists as well as by 
me. I therefore propose the following characters for the genus 
IpHITEON, Valenciennes. 
Skeleton siliceo-fibrous. Fibre solid, cylindrical. Reticulations 
symmetrical. Areas rotulate, confluent. 
Type Iphiteon panicea from Porto Rico, Museum of the Jardin des 
Plantes, Paris. 
* For Part I. see ated, pp. 66-LO0, 
