Anatomy of Horny Sponges. 173 



which they but ravelj 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 fibrill^e large tracts 

 of fusiform cells which clearly belong to the connective tissue 

 of the sponge. Lower down these tracts spread out, and 

 nascent fibrils ai-e 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. 



Tiie 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 Filiferai 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 siiining, and is provided with 

 numerous conuli, which are more widely separated than in 

 Hircinia, but less, so than in Spongeliay 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 Eusjjongia. 



There is much difficulty in eliminating this tissue by 

 maceration ; but after doing so, there remains a skeleton of 

 very coarse fibres, widely 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 Ghondrosice\ while by its canal- 



Ann. & Mag. N. Hist. Ser. 6. Vol. vi. 13 



