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



to the descriptions published by him of several species, we have been able to refer to 

 specimens in the British Museum named by Mr. Carter himself, and it is from these and 

 from the good series brought home by the Challenger that the above diagnosis has been 

 drawn up. 



These remarkable honeycombed sponges appear to be very abundant off the south 

 coast of Australia, and the question of their specific differences and their relations to 

 other genera is a very difficult and intricate one. They are probably reduced Clathriids, 

 in which, from the strong development of horny fibre rendering them unnecessary, the 

 spicules are gradually disappearing, or, in other words, they are Clathriids on their way 

 towards becoming horny sponges without spicules. Carter has described no forms with 

 microsclera, but we have shown (see under Echinoclathria favus and Echinoclathria 

 carteri) that palmate isochel^, such as are found in typical Clathrise, may be present. 

 That the genus is closely allied to Claihria there can be no doubt, but it may be 

 distinguished from the latter by the absence of a distinct kind of spined echinating 

 stylus from the spicular complement ; the fibre is, however, echinated by the smooth 

 skeleton stylus or subtylostylus. 



In accepting Mr. Carter's generic name, Echinoclathria, we hesitated before venturing 

 to give a definite generic diagnosis. The present one must be regarded as preliminary. 

 Before a satisfactory diagnosis becomes practicable a more extensive study of the group 

 is required. The peculiar honeycombed external appearance is certainly very character- 

 istic, but can hardly be regarded as absolutely distinctive ; Clathria frondifera, Bower- 

 bank, makes a near approach to it, and Carter includes in his genus Echinoclathria 

 several forms which do not possess it.^ 



Echinoclathria favus, Carter (PI. XXXI. figs. 4, 5, 5«). 



18S5. Echinoclathria f amis, Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. xvi. p. 292. 



Sponge (PI. XXXI. figs. 4, 5) massive or branched, lobate or digitate, commonly 

 growing over the shells of living Pectens. Honeycombed throughout ; consisting of a 

 close reticulation of anastomosing and interwoven trabeculse, with round or oval meshes 

 between; the meshes on the surface may be either closed in marginally or Mseandriniform. 

 Size very variable, the largest specimen is about 162 mm. high and 75 mm. broad. 

 Colour in spirit greyish-yellow. Texture of trabeculse tough, rather cartilaginous. 

 Surface very minutely hispid. Dermal membrane thin, transparent, very rarely 

 (PI. XXXI. fig. 5a, m) stretching across the meshes at the surface of the sponge. Oscula 

 (PI. XXXI. fig. 5a, o) minute, scattered over the surfaces of the trabeculse. 



1 Viz., Echinoclathria tenuis, Echinoclathria nodosa, Echinoclathria suhhispida, Echinoclathria gracilis (Ann. and Mag, 

 Nat. Hist., ser. 5, vol. xvi. pp. 355, .356), but whether these really belong to the same genus as Echinoclathria favus, 

 which is mentioned before any of them {ibid., p. 292) is another question, into which we cannot here enter. 



