Zoorpuyta. | LOWER PALZEOZOIC RADIATA. ial 
a bundle of thread-like rods of silica, corresponding exactly in diameter with the external ridges, the sections of 
which exactly correspond with the others in the interior; the siliceous fibres are solid, cylindrical, with slight 
occasional transverse rugosities ; they are less than their own diameter apart, and the interstices shew no organi- 
zation under a magnifying power of 330 diameters, the limestone being of a finer texture and lighter colour 
than that of the matrix, as if there had been originally a soft animal matter in the spaces between, which kept 
out the coarse calcareous mud, but the space occupied by which became filled with fine material by percolation 
on its decomposition. Iam therefore inclined rather to compare the fossil in question with the Hyalonema of 
Gray, of which a short notice was published in the Zoological Proceedings 1835, being, according to that 
naturalist, a recent marine zoophyte allied to Gorgonia, called glass-plant by the English at Canton. It has 
a long, thick, rope-like axis, formed of a bundle of very long, slightly-twisted threads of pure silica, held 
together by a little animal matter, the whole having an external animal pulpy layer in which the polyps were 
lodged, and which falls away at their death, leaving the siliceous axis of glass-like fibres exposed. The analogy 
between these seems to me very strong, and J know of nothing else in nature like the fossil. I have named 
the genus from Mupirns, silew, and vjpa, filum. Lest the specimen might be supposed to resemble a bundle 
of certain Serpule, I may mention that the rods of silica are not tubes, and have no walls. 
Explanation of Figures.—Plate 1. B. fig. 13. Natural size from the Limestone of Tre Gil—Fig. 13 a. 
Portion of ditto magnified three diameters, shewing the external surface of the bundle of tubes with irregular 
transverse plicze, and shewing in the horizontal section at top the termination of the various filaments in the 
interior of the mass.—Fig. 134. Do. Smaller portion more highly magnified, shewing the absence of inter- 
mediate structure or walls to the tubes. 
3rd Fam. TUBIPORID (see p. 9). 
Genus. FISTULIPORA (J/‘Coy). 
Ref.—M°Coy, Annals of Nat. Hist. 2nd 8. Vol. III. p. 130. 
Gen. Char—Corallum incrusting, or forming large masses, composed of long, simple, cylindrical, thick- 
walled tubes, the mouths of which open as simple, equal, circular, smooth-edged cells on the surface, and 
having numerous transverse diaphragms at variable distances; intervals between the tubes occupied by a 
cellular network of small vesicular plates, or capillary tubules traversed by diaphragms. 
This genus was proposed to include the Manon cribrosum (Gold.) of the Eifel, &c., and some new species. 
They have no affinity with the fossil sponges of the genus Manon, with which the only previously known 
species was classed by Goldfuss and others, but are more allied to the so-called Porites of the palzozoic 
rocks (Palewopora, M°Coy), from which they differ in the absence of the rudimentary radiating or vertical 
lamellze to the cell-tubes. The sides of the tubes do not seem to be perforated by connecting pores. The 
absence of vertical lamellee induces me to place this genus among the Zoophytaria, in the family Tubiporide, 
from the type of which (Zwdipora) it will be found not to differ materially. In Twbipora we find exactly 
similar main tubes, but with rather less regular diaphragms: that is however merely a question of degree ; the 
only positive difference between these genera is, that in Zwipora the connecting vesicular tissue is developed 
only in distant horizontal layers with clear interspaces, while in J’istulipora it fills all the space between 
the main pipes. 
FISTULIPORA DECIPIENS (J/°Coy). 
Ref—M°Coy, Annals and Mag. Nat. Hist. 2nd Series, Vol. VI. p. 285. 
Sp. Ch.—Corallum forming hemispherical or subcylindrical masses three or four inches in diameter, 
concentrically wrinkled at base; cell-tubes straight, subparallel, with moderately thick walls, leaving clearly 
definite, circular, smooth-edged cells in the transverse section, very regular in size and disposition, usually 
slightly less than half a line in diameter, and averaging rather less than their diameter in the shortest 
line between adjacent cells, in which line there are usually two, or more rarely three, of the intermediate 
vesicular cellules; about eighteen of the intermediate or polygonal cellules in the space of two lines ; 
c2 
