152 THE VOYAGE OF H.M.S. CHALLENGER. 



Although the language is a little ambiguous there is no doubt that sigmata are here 

 referred to. 



Mr. Carter's genus " Echinonema " must be suppressed, as the species which it 

 includes are not generically separable from the older genus " Rha^jhidophlus," which 

 Mr. Carter appears never to have recognised.^ The genus " Rhaphidophhts" has a 

 further claim to take precedence of " Echinonema " in that its founder gave a generic 

 diagnosis thereof. 



Rhaphidophlus gracilis, Ridley, sp. 



1884. JEchinonema gracilis, B.idlej, Zool. Coll. H.M.S. "Alert," Brit. Mus., p. 617, pi. liv. 



figs. 1, r, 1". 



One specimen of this species was obtained by the Challenger off Bahia. It agrees 

 very minutely in external form and in spiculation with the type, but instead of being 

 of a " very dark purplish -brown colour " (in spirit), it is greyish -yellow. It is very 

 interesting to find this well-marked species occurring at two so widely separated 

 localities as the Mascarene Islands and Bahia. 



Locality. — Off Bahia ; dejsth, 7 to 20 fathoms. One specimen. 



Habitat. — Providence Reef, Mascarene Islands (Ridley, " Alert ") ; off Bahia 

 (Challenger), 



Rhaphidophlus filifer, Ridley and Dendy (PI. XXVIII. fig. 2 ; PI. XLVI. fig. 9). 



1886. Rhaphidophlus filijer, Ridley and Dendy, Ann. and Mag. Nat Hist., ser. 5, vol. xviii. 



p. 475. 



Sponge (PI. XXVIII. fig. 2) irregularly ramose ; branches approximately cylindrical, 

 but very uneven and with a gnarled appearance ; the habit of the sponge appears to 

 have been suberect or creeping. Colour in spirit greyish-yellow. Length of specimen 

 94 mm., average diameter of branches about 6 mm. Texture hard and almost incom- 

 pressible. Surface very rugose and uneven, but with a slightly glabrous appearance. 



Skeleton (PL XLVI. fig. 9). — [a) Dermal; consisting of a compact crust, about 0'14 

 mm. in thickness of densely packed, projecting brushes of stylote spicules with outwardly 

 directed points. When viewed in surface section these tufts are seen to be arranged in a 

 reticulate manner, so as to form approximately circular meshes about O'l mm. in diameter. 

 (&) Main ; a well-developed, but rather irregularly disposed reticulation of spiculo-fibre ; 

 one can in places roughly distinguish primar)^ fibres, running towards the surface, from 

 secondary fibres which cross them more or less at right angles and thus give rise to 

 approximately rectangular meshes. The fibre itself is stout and well defined and is 



1 Cf. also Ridley, Zool. Coll. H.M.S. "Alert," Brit. Mus., 1884, p. 61.5. 



