REPOET ON THE KERATOSA. 67 



Stelospongos longispinus, Fonbressin et Miclielotti, sp. (PL VI. fig. 15; PL VIIL fig. 4). 



Polytherses longispina, Fonbressin et Miclielotti, Spongiaires de la mer Caraibe, p. 71. 

 Hircinia acuta, var. longupina, Hyatt, Revision, &c., vol. ii. p. 549. 



The descriptions of Fonbressin and Michelotti and Hyatt agree closely with 

 the properties of one specimen of the Challenger collection, and I have no 

 doubt that I am right in identifying it with Hircinia acuta, var. longispina of Hyatt. 

 How far the other varieties of this species distinguished hy Hyatt are really to l)e 

 referred to the genus Stelospongos, I am not prepared to say, but it is obvious that 

 the conjectural variety we are speaking of is a true Stelospongos. Hyatt himself says, 

 " In fact, so strong is the resemblance (lietween a Stelospongos and the form in question) 

 that it was at first classified with that genus," but constant to his dermal-membrane 

 theory of the formation of the skeleton, he assigned to the form another systematic 

 position. Now we know that the theory just cited is false, and a different procedure 

 is necessary. Indeed, when compared with Stelospongos maynardii, or any other true 

 Stelospongos, our specimen is not a typical representative of the genus. It is but seldom 

 that one can distinguish in the columns constituting the skeleton — some of which are 

 represented on PI. VI. fig. 15 — the vertical primary, and more or less horizontal secondary, 

 fibres, but in some instances this distinction is still evident, and accordingly there can 

 be scarcely any objections to the proceeding adopted here. 



The specimen proved to be full of sperm-balls, and in a far greater degree of 

 filaments, one of which is represented on PL VIIL fig. 4. 



Colour. — Outer surface dark grey, parenchyma dirty white, skeletal-fibres pale 

 yellow. 



Habitat. — Off Barra Grande, September 10, 1873 ; depth, 400 fathoms; red mud. 



Carteriospongia, Hyatt. 



Spongidae of flabellate, leaf-like, or funnel-shaped form, with skeletal-fibres admitting 

 of a distinction into larger primary and smaller secondary ones, with flagellated chambers 

 usually devoid of any inhalent and exhalent canaliculi, with ribbed outer surface. 



Carteriospongia radiata, Hyatt (PL IV. fig. 5 ; PL V. figs. 7, 8, 9). 

 Carteriospongia radiata, Hyatt, Revision, i&c., vol. ii. p. 541. 



There are in the Challenger collection four specimens of the genus Carteriosjjongia, 

 three funnel-like, the fourth presenting a colony of leaf-like individuals, which with regard 

 to the properties of their skeleton — except that the " veil " of Plyatt proved to be propped 

 up not by a network of skeletal fibres but by foreign enclosures — and to those of the outer 



