172 
M. H. Fol on the 
may be readily distinguished from either by its elongated 
snout, which allies it to the four species first mentioned. Of 
these, 8. laticaudatus is separated by its larger size, shorter 
hair, browner colour, nearly white belly, and still longer 
muzzle ; S. rufigenis by the brilliant rufous of its cheeks and 
the underside of its tail ; 8. Pernyi by its similarly rufous 
tail ; and S. Berdmorei by the black and white longitudinal 
stripes with which its body is ornamented. No other species 
that I can find have any close relationship to the new form 
discovered by Mr. Everett, in whose honour I have very 
great pleasure in naming it. 
XXI. — On the Anatomy of Horny Sponges belonging to the 
Genus Hircinia, and on a new Genus . By H. Fol *. 
The genus Hircinia was created by Nardo in 1833 for 
certain horny sponges possessing two systems of fibres — some 
coarse and analogous to those of the bath-sponge ( Euspongia ;) , 
and others very fine and numerous, resembling the elastic 
fibrillse of the connective tissue of Vertebrates. The structure 
of these fibrillse was investigated by Lieberkuhn, O. Schmidt, 
and F. E. Schulze, who showed that they do not anastomose, 
but terminate in all directions in rounded swellings. The 
two latter authors, however, like Kolliker and Hyatt, con- 
sidered that these fibrils probably belonged to a parasite or to 
a commensal of these sponges. It was for this reason that 
the family Filiferse was actually abandoned ; so that Vos- 
maer, in his monograph of the Spongiariae, does not recognize 
a single genus belonging to this family, and suppresses it. 
Sections which 1 have made of specimens of Hircinia 
variabilis and Hircinia sp. n., from the neighbourhood of 
Nice, have enabled me to solve the disputed question of the 
origin and nature of the fibrillse, and this in a sense opposed 
to that of recent authors. 
On making a series of somewhat thick transverse sections 
of a specimen macerated for a few hours only, so as to sepa- 
rate the epithelia while leaving the connective tissue un- 
touched, we see at once in the clearest possible way that the 
fibrils are not disposed at random, as would be the case were 
we dealing with a parasite, but form a system of incomplete 
septa, which alternate with the fibres of the skeleton, with 
♦ Translated from the * Comptes Rendus devS Stances de V Academia 
des Sciences/ tome cx., June 9, 1890, p. 1209 et seq. 
