140 Mr. H. J. Carter on Sponges from the 
posed of a heterogeneous assemblage of sand and fragments 
of various sponge-spicules, together with what appears to be 
the siliceous globules of a Geodia and the branches of a lithistid 
sponge-spicule (figs. 8, d, and 9, 6) ; but as the former is some- 
times evidently botryoidal chalcedony, and the latter, from its 
frequency, may be a fibrous form of the same mineral, it is not 
safe to assume that these two forms were ever organic. Size 
of largest and best-formed specimen about half an inch in 
diameter (fig. 7). 
Hab. Marine, in company with Hyalonema Smithit. 
Loc. Upper thin beds of Lower Carboniferous Limestone, 
Cunningham Baidland, Dalry, Ayrshire, S.W. Scotland. 
Obs. From the structure and composition of the reticulated 
fibre of which this fossil is composed, it may fairly be inferred 
to have been a sponge belonging to my order Psammonemata, 
probably of the family Hircinida and 16th group, viz. Arenosa ; 
even now, from its appearance, it might almost be mistaken for 
a living Dysidea it on the rocks where the latter grows. 
There are several specimens, of which the largest and most 
perfect is that above described. Having directed a stream 
of water over it for some time, the material thus washed off 
was mounted in balsam, which presents, on microscopic exa- 
mination, fragments of a variety of spicules, together with 
grains of quartzose sand, from which a few of the former have 
been figured ¢o scale for illustration (fig. 9, a). 
Rhaphidhistia vermiculata, n. sp. (Pl. LX. figs. 15-19.) 
Siliceous fossil. Laminiform, parasitic on a species of 
(?) Hydractinia (fig. 15). Composed of acerate, vermicular 
spicules lying confusedly together on the surtace of the fossil 
Hydractinia (fig. 16, a), which consists of a convex, subcir- 
cular, depressed mass of more or less erect, conical, columnar 
processes, sometimes unequally bifurcate at the apex, rising 
from a reticulate structure of the like nature (fig. 16), based 
on a continuous membranous attachment now lapidified 
(fic. 16, cc), about half an inch in horizontal diameter, which 
is the size of the superincumbent mass. Processes about 
1-12th inch high by about 3-48ths inch wide at the base, com- 
posed of chalcedony with a saccharine crystallization on the 
surface (fig. 17) and a central axial hollow closed at the 
summit (fig. 16, e, b), covered in some instances with the layer 
of vermiculate spicules above mentioned, one end alone of each 
of which is visible on account of the other being hidden beneath 
its neighbours (fig. 18). Spicule smooth, apparently acerate, 
fusiform, vermiform, and abruptly pointed at each end 
(fig. 19); about 1-900th inch in diameter and about 1-90th 
