144 Mr. H. J. Carter on Holasterella and Hernia,sterella. 
surface of the fossil sponge. Thus it is interesting to find that 
at that remote period a crustacean parasite nestled in the sur¬ 
face of the Holorhaphidotic sponges as at the present day. 
But up to this time no recent sponge has been made known 
which possesses, for the most part, a comparatively bodiless 
stelliform spicule of this kind only—that is, a stellate without 
central inflation. The globostellate or spiniglobate spicule 
of Chondrilla nucula , Sdt., is thus totally different in form, and 
the sponge itself inclined to a horizontal rather than an erect 
growth. 
There are, however, recent sponges which are partly com¬ 
posed of stellate spicules of a similar form, and thus so far 
resemble Holasterella , and which also appear to belong to the 
Subcritida. Thus Xenospongia patelliformis , Gray (Proc. 
Zool. Soc. 1858, p. 230), is half composed of bodiless stellates 
of different sizes, together with a long, setaceous, linear, acuate 
spicule, and a new genus, which I am about to describe pre¬ 
sently under the name of “ Hemiasterella .” 
Besides the more perfect portions of Holasterella, Mr. Thom¬ 
son has kindly sent me many other fragments of this sponge, 
more or less consolidated by the fossilization, all of which 
come from a compact earthy rock or stratum of an ochraceous 
or ferruginous colour that does not effervesce with acids. It 
has already been stated that they are composed of white, opaque, 
translucent, and transparent “ heavy spar ” (sulphate of ba¬ 
rytes), according to its position, which having in many in¬ 
stances assumed a subpisolitic structure, from the mineral 
chiefly accumulating round and extending outwards from the 
central inflation or body of the stellates respectively, in which, 
the points of one or more of the rays only being sometimes 
projecting, a more or less solid mass of crystalline material is 
produced, and the spheroidal portions average 1-12th inch 
in diameter. It should here be remembered that not effer¬ 
vescing with acids is no test that the material is siliceous ! 
Thus, then, the stellate represented in fig. 11 ( c Annals,’ 
1878, vol. i. pi. ix.) has been identified in situ, and the sponge 
thus found to which it belongs ; and thus also we may fairly 
anticipate that some day the same thing may happen to the 
stellate (fig. 10 ib.) and the sponge to which this belongs also 
be identified; if not, to other spicules of a different form which 
may be abundant in the same deposit, such as fig. 11, to 
which I shall now allude. 
This spicule is cylindrical and smooth, with straight shaft 
and obtuse round ends bent upon the shaft in the same direc¬ 
tion (fig. 11). It varies much in measurement, losing, like 
the spicules of all other sponges, in one way, viz. in length, 
