Carboniferous of the S.W. of Scotland. 139 
bodies such as fragments of shells &c. (fig. 2, eee), while 
the remote parts, as above mentioned, are occupied by opaque 
white crystalline calcite alone. The widest parts, too, being 
on the side of the large central excavation, and particularly 
leading into the excavation itself (fig. 2, @), would seem to show 
that this was the excretory side, and that the principal outlet 
was at this excavation; while the smaller venation being on 
the opposite side of the fossil, seems to point out that this was 
more particularly the “ pore-surface,” which, if the sponge 
grew from the roof of a submarine rocky cavern pendent from 
the stem-like portion in the smaller excavation (fig. 2, 0, c), 
would indicate its upper part, and vice versé if it grew from 
the upper surface of the rock or material on which it was 
originally fixed; for it has every appearance of having once 
been pedunculated. 
The specimens (of which there are three) are not all exactly 
alike in their general shape: two, growing from a flat circular 
base, have risen into a depressed truncated conical form ; 
another has a smooth unequal or undulating subconical side, 
with three large holes almost equidistant from each other and 
from the circumference, which, together with the central excava- 
tion, look very much like the remains of large vents. 
The former (fig. 1) appears to be the prevailing form; but 
independently of an original difference in this respect, some- 
thing must be allowed for subsequent alteration during the 
time the sponge was loose on the sea-bottom before fossiliza- 
tion, and something afterwards ; hence it would be absurd to 
expect that all the specimens should be alike in general form 
any more than those of recent sponges. 
All the spicules with the rest of the fossil are calcareous ; 
at the same time it is worthy of remark that when dilute 
nitric acid is applied to the surface of a polished vertical sec- 
tion where the spicules may be observed to le horizontally, 
and the part then subjected to gentle edulcoration with water, 
more or less of the spicules is left in relief on the surface, 
which, although in a friable state, as in Pharetrospongia 
Strahani when treated in a similar manner, seems to indicate 
a lingering remnant of their original siliceous composition. 
Dysidea antiqua, n. sp. (Pl. X. figs. 7-9.) 
Siliceous fossil. Small, massive, globular, sessile, reticulate 
(fig. 7). Surface uniformly reticulate (fig. 7, a), being a con- 
tinuation of the internal structure, which is composed of mas- 
sive reticulation (fig. 8). Fibre of reticulation about 1-96th 
inch in diameter ; interstices about 3-48ths inch wide ; com- 
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