THE 
MONTHLY MICROSCOPICAL JOURNAL. 
DECEMBER 1, 1870. 
I.— On a New Anchoring Sponge, “Dorvillia agariciformis.” 
By W. Savintz Kent, F.Z.8., F.R.MS., of the Geological 
Department, British Museum. 
(Read before the Royau Microscoprcau Society, Nov. 9, 1870.) 
Puiate LXVI. 
Dr. J. E. Gray placed in my hands yesterday morning, with kind 
permission to describe it, the sponge which, with an accompanying 
plate in illustration of its structure, I exhibit on the present occasion. 
The form is a remarkable one. In external aspect it presents 
much the appearance of a “ button mushroom” just springing from 
the ground, having several bundles of long filiform spicula depending 
from its lower surface. It may be said to be divided into two dis- 
tinct portions: an upper, which takes the form of a hood, and cor- 
responds to the “ pileus” in making use of the fungoid comparison ; 
and an inferior, bearing a rough resemblance to the stalk. 
The supporting skeleton of this sponge 1s entirely silicious, having 
its component elements disposed in the following order. From 
the interior and basal portions we find radiating in every direction 
dense fascicles of stout spicula having their external extremity 
trifid and dichotomously branching, “ Bifurcated expando-ternate ” 
Bowerbank, as shown at Plate LXVI., Figs. 6 and 7. The inter- 
lacing ramuli of these spicules alone are exposed to the surface 
in the basal portion of the sponge. The surface of the upper part, 
however, presents quite a felty appearance, which arises from a 
mesh-work of anchorate, hexradiate, attenuate, and other varieties 
of spicula which are superimposed on the outer branching extremities 
of the trifid forms. The attenuate and anchorate spicula have fre- 
quently a definite fascicular arrangement. Immediately beneath 
the surface of the hood, and connecting it with the lower portion of 
the sponge, is a beautiful open reticulation of the sarcode, as shown 
at Fig. 3. Highly magnified, this net-work presents the appearance 
given at Fig. 4, and is found to be almost completely filled with 
minute irregularly stellate spicula, isolated and still more highly 
magnified examples of which are shown at Fig. 5; this reticulation 
VOL. IV. ¥ 
