Carboniferous of the S.W. of Scotland. 141 
inch long, which is that of the longest exposed portion. 
Thickness of the layer inappreciable, extent depending on the 
quantity of the Hydractinia covered by it. 
Hab, Marine, in company with Hyalonema Smithit. 
Loc. Upper thin beds of Lower Carboniferous Limestone, 
Cunningham Baidland, Dalry, Ayrshire, 8.W. Scotland. 
Obs. From the general form and reticulate structure of this 
fossil (fig. 16) it appears to be more like a species of Hydrac- 
tenia than any thing else, subsequently overgrown by the 
layer of vermitorm spicules mentioned. If the whole belonged 
to the sponge, then it was wholly one, and not parasitically 
overgrown by the layer of sponge-spicules, which now form, 
on the columns covered by them, a continuation of the sub- 
jacent material (chalcedony). But, out of several specimens, 
as there are as many without as with this covering, while 
the columns are hollow and not solid, it seems very likely 
that Lhaphidhistia vermiculata was a parasitic laminiform 
sponge very much hke Hymeraphia vermiculata, Bk.; but the 
large erect pin-like spicules of the latter do not appear to be 
present. There are many minute recent sponges, however, 
that are laminiform without the large erect pin-like spicule 
which characterizes Dr. Bowerbank’s suborder Hymeraphia, 
some of which I may hereafter have to describe under the 
generic name Lihaphidhistia. 
If this was a Hydractinia parasitically covered by the sponge, 
then it was probably a calcareous one which subsequently 
became chalcedonized and finally encroached upon by calcite ; 
for many of the conical processes are as much eroded by rhom- 
bohedral excavation as the spicules of Hyualonema Smithit 
already mentioned ; while this is also the case with many of the 
minute chalcedonized shells which Dr. Millar sent me from the 
disintegrated or “rotten” limestone, wherein there can be no 
doubt that the shell was calcareous in the first instance. Hence 
there is yet much in palexontology that requires elucidation 
by the chemist. 
EXPLANATION OF THE PLATES. 
PLateE IX. 
Fig. 1. Hyalonema Smithii, Y. & Y. Fragment of cord imbedded in 
Encrinital Limestone, natural size. “a, upper; 6, lower end. 
Fig. 2. The same. Transverse section of the upper end, nat. size. 
Fig. 3. The same. Fragment of anchoring end of cord-spicule ; lateral 
view. 4d, view of free end; 0b, view of shaft side. x 2. 
Fig. 4. The same. Magnified, in situ. a, fragment of anchoring end. 
Fug.5. The same. More magnified lateral view, to contrast with the 
following form. 
Fig. 6. ? The same. Anchoring end of cord-spicule, with four arms 
opposite and much recurved ; double sagittate. 
