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manner as the fibres of the Mediterranean sponge of commerce, and 
in the places where they were intersected they frequently exhibited 
the internal cavity. These characters, the author remarks, prove 
that the red fibre is the cast of the interior of the tube, and its dia- 
meter, he adds, is as nearly as possible the same as that of the 
hollow of the tube. In a moss agate from Oberstein the walls of 
the best-preserved tubuli were charged with red pigment, and the 
internal cavity was filled with pellucid silex, while the portion which 
had suffered most from decomposition was a confused bright red mass 
with obscure traces of fibrous structure. 
In the green jaspers from India the organic remains were found 
to be generally better preserved than in the moss agates of Germany 
and Sicily, and admitted of being recognised as distinct species. 
The green colouring matter was confined, with very few exceptions, 
within the boundaries of the sponge-fibre, the surrounding matter 
consisting of minute pellucid radiating crystals. Some of the spe- 
cimens examined by Mr. Bowerbank were furnished with minute 
contorted tubuli, very similar to those which are described in his for- 
mer paper*™ as occurring upon the surface of chalk-flints. In other 
_ specimens the fibres were not disposed in the same manner as in the 
sponge of commerce, but in a series of thin plates, resembling very 
much the macerated woody fibres of the leaves of some endogenous 
plants. Only one recent species, from Australia, is known to Mr. 
Bowerbank to exhibit this structure. 
No spicula are mentioned by the author in either the agates or jas- 
pers, and but one instance of the occurrence of foraminifera. The whole 
of the sponges contained in the green jaspers, Mr. Bowerbank refers 
to that division of the keratose which he has called Fistularia. 
2. Gemmules.—A specimenof Indian green jasper, which had under- 
gone so great decomposition as to prevent the original fibrous structure 
from being detected, presented innumerable globular vesicles of nearly 
uniform size. Many of them were simple and transparent, and could 
be recognised as organic only by the regularity of their size and form, 
and by having universally dispersed over their outer surface minute 
irregular black particles; but by far the greater number of them 
had in their interior a globular opaque body, about one-third their 
own diameter. Associated with these vesicles were numerous small 
fibrous masses resembling minute keratose sponges, the largest of 
which were five or six times the diameter of the vesicles; but the 
smallest were identical in nature with the nucleus, though in a higher 
state of development. In other specimens from the same mass of 
jasper, larger vesicles were found more sparingly imbedded amidst 
the fibrous tissue of the sponge. From these characters and their 
resemblance to those of the ova of some recent sponges, Mr. Bower- 
bank has little doubt that the vesicles are the fossilized gemmules of 
the sponges which gave the form to the siliceous masses in which they 
are imbedded. An agate supposed to have come from Oberstein, 
presented characters which, Mr. Bowerbank is of opinion, indicated 
* Geol. Trans., 2nd Series, vol. vi. Part 1. 1841. 
VOL. III. PART II. : 20 
