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



Skeleton. — In each branch there is a central axis, formed of a very dense reticulation 

 of closely packed, tylostylote spicules. These pass into rather loose and irregular, 

 radiating fascicles of spicules, which terminate in a " dermal crust," composed of 

 divergent brushes of tylostylote spicules whose points project very slightly beyond 

 the surface. Just below the surface there also occur a few more or less horizontally 

 placed spicules, which, together with the radiating brushes, are so arranged as to give to 

 the surface its reticulate appearance. 



Spicules. — Megasclera ; of one kind only, viz., smooth tylostyli (PI. XLV. figs. 7, 

 7a, 7b, 7c, 7d), almost or quite straight, with well-developed, nearly globular heads and 

 slightly fusiform shafts, tapering very gradually to a very sharp point at the apex. In 

 size these spicules vary very much, smaller ones being found towards the outside and 

 larger ones in the centre of the sponge. Often in the case of the smaller spicules the head 

 and neck are bent at a slight angle to the remainder of the shaft. The spicules vary in 

 length from about 0'175 to about 0'875 mm., and in diameter from about 0'0094 to 

 about 0'025 mm.; the spicules in the dermal crust being commonly about 0'28 mm. 

 and those of the deeper parts about 0'7 mm. long. 



Mr. Carter refers twice in the Annals and Magazine of Natural History to his 

 Suherites antarcticus,^ and as his type of the species (dry) is in the British Museum 

 there is no doubt as to what the species really is, although it has not hitherto been 

 fully described. The above description is taken entirely from the Challenger specimen, 

 which is a very fine one, and preserved, of course, in spirit. In Mr. Carter's specimens 

 the branches are much more flattened and very much mpre anastomosing than in the 

 Challenger example. 



It will be seen that this species comes near to Suherites 'perfectus, nobis, but it 

 differs from it in its manner of growth and in its extraordinary dark colour (?), which 

 may be a very characteristic feature. There are also slight diff"erences between the 

 spicules of the two species, but these do not amount to much. 



Locality. — Off" Christmas Harbour, Kerguelen ; depth, 70 fathoms. One specimen. 



Habitat. — Antarctic Seas (Carter) ; Kerguelen (Challenger). 



^ Loe. (it. supra and Ann. and. May. Nat. Hid., ser. 5, vol. ix. p. 350. Mr. Carter here says: — "Dredged by Sir 

 James Ross in 74^° S. lat., in 206 i'atlioiiis (Expedition of 1841), undescribed. Character. Stipitate branched; 

 branches digitate, nodose, pollachotomous ; structure subcavernous ; colour dark house-mouse ; spicule pin-like, with 

 large spherical head. Size of specimen about 5| x 3 inches." 



