Anatomy of Horny Sponges . 173 
which they but rarely come into contact. If we choose, for 
the purpose of cutting sections, a portion in process of rapid 
growth, we shall find in the place of the fibrilke large tracts 
of fusiform cells which clearly belong to the connective tissue 
of the sponge. Lower down these tracts spread out, and 
nascent fibrils are observed on which the fusiform cells 
are disposed like a string of beads. Further on still the cells 
have atrophied, and there only remains their product, the 
fibril. 
The authors mentioned were therefore wrong in holding 
without a particle of proof that the fibrils were the work of 
an unknown parasite ; on the contrary, they form an integral 
part of the sponge. The family Filiferas must be reinstated, 
as being the surest and best characterized division of all those 
which have been made in the order of Horny Sponges. 
There is met with in abundance in the waters round Nice a 
blackish sponge of large size, which I cannot discover has ever 
been described. This sponge adheres tenaciously to rocks ex- 
posed to the open sea, at depths of from 10 to 30 metres, and 
it can only be collected by aid of the diving-dress. It attains 
the size of a man’s head. In colour it is of the neutral tint 
of water-colour painters ; it is shining, and is provided with 
numerous conuli, which are more widely separated than in 
Hircinia , but less so than in Spongelia , and with a very small 
number of large oscula. If left to itself in an aquarium a 
larger number of oscula open after a few hours ; these are 
very minute and are situated between those already men- 
tioned. 
This sponge is friable, owing to the fact that the fibres of 
its skeleton are wide apart ; but its tissue is very dense and 
in section reminds one of calf’s sweetbread. It consists for 
the most part of a compact and almost indestructible con- 
nective tissue, in which are lodged canals and flagellated 
chambers, disposed as in Euspongia. 
There is much difficulty in eliminating this tissue by 
maceration ; but after doing so, there remains a skeleton of 
very coarse fibres, wddely separated, but anastomosing and 
affecting a regular disposition. These fibres are hollow, 
composed of several concentric sheaths, and enclose, in their 
axis only, numerous foreign bodies of large size, such as 
grains of sand, pieces of the skeleton of other animals, &c. 
This sponge, then, comes between Spongelia and Aplysina 
by reason of its skeleton ; by its tissue, which offers a much 
greater resistance to the action of chemical agents than that 
of Aplysina , it recalls the Chondrosice ; while by its canal- 
Ann. & Mag . N. Hist . Ser. 6. Vol. vi. 13 
