142 Mr. H. J. Carter on Holasterella and Hemiasterella. 
so as to present a minutely convoluted appearance, in the 
interstices of which minute round holes exist, indicative of 
the position of the pores (fig. 2, b). Vents not observed, but 
the canals of the excretory system evident internally. Stel¬ 
late spicule normally composed of twelve rays or arms, viz. 
six above (that is, with five round an axial one), and the same 
below, but less regularly disposed, projecting from a central 
inflation, which is most evident in the smaller or younger 
forms; the six upper rays during growth remaining almost 
stationary, while those below undergo the chief increase in 
size, so as to produce a stellate like the one to which I have 
alluded, in which some of the smaller arms or rays of the 
head occasionally appear to be microspined (figs. 4, 5). But 
since this is the normal form, and only seen in the young 
stellate, the regularity becomes for the most part widely de¬ 
parted from as the stellate increases in size, when the rays, 
sometimes rendered more numerous by bifurcation (fig. 5, a), 
and sometimes less by abortive development, often terminate 
in a most irregular form, composed of four to fourteen rays or 
more, variable in length and variously disposed; while the 
central inflation, which does not keep pace with the enlarge¬ 
ment of the arms, remains hardly appreciable (compare figs 4 
and 8). Diameter of largest stellates about l-6th inch (fig. 3), 
size of smallest stellate seen (from the surface) about 1-545th 
inch in diameter. The larger spicules are confined to the in¬ 
terior ; and the small spicules occupy the surface both of the 
sponge itself and of the excretory canals, mixed with the 
pointed ends of the rays of tire larger spicules in the latter, 
which project freely into them (fig. 8), while the larger 
spicules again, where still provided with the head surmounted 
by the six smaller ones (figs. 4, 5), are so arranged in some 
parts of the surface of the sponge as to present a number of 
rosettes like stars more or less approximated. Size of entire 
specimen 5f inches high, greatest diameter of head 2 inches, 
diameter of base or stem f inch. 
Hob. Marine. 
Loc. Highest bed of Upper Limestone of the Carboniferous 
rocks of the south-west of Scotland, near Glasgow. 
Obs. This specimen, which was originally entire, but on 
extrication became broken into four pieces, and reached me in 
this state, was easily put together for the purposes of illustra¬ 
tion and description, as fig. 1, a, b, c, d , shows. The accumu¬ 
lation of the mineral (sulphate of baryta) of which it is com¬ 
posed, having more or less thickened the body (that is, the 
central inflation) and rays of the stellates respectively, has 
thus caused them also to become more or less amalgamated 
