510 " THETIS " SCIENTIFIC RESULTS. 



Surface partly covered with a thin transparent membrane 

 beneath which may be traced a series of subradiating grooves 

 about 0"5 to 1 mm. in diameter. The abraded surface is finely 

 pilose, and velvet like to the touch. Texture soft, flexible, 

 elastic, and tough ; colour generally olive brown, but inclined to 

 grey where the epidermis is intact. 



Skeleton consisting of rather slender, but numerous whispy 

 bundles of moie or less plumosely arranged spicules, which 

 terminate in divergent tufts at the surface. 



Megascleres : — (1) Straight or but little curved styli with a 

 well rounded base and an acute apex; size 0*4 to 0'45 by O'OOS 

 to 0012mm. 



(2) Short styli frequently with a slight bend near the base ; 

 size 0-15 by 0-004 to 0-005 mm. 



(3) Slightly curved oxea ; .size 0-11 by 0-0035 mm. The oxea 

 are very scarce and occur chiefly in or near the dermal portion of 

 the sponge. 



AXINELLA VERMICULATA, sp. nov, 



(Plate xlvi., fig. 43.) 



Station 53. 



Sponge stipitate, flabellate, but equally expanded ; the mar- 

 ginal border is rather thin and exhibits a series of irregular 

 lobes, separated by incisions of varying width and depth. 



Surface generally minutely conulose, neatly reticulate, and 

 finely porous. The most striking features, however, are the 

 numerous subradiating ridges and grooves ; the latter are usually 

 from 2 to 3 mm. wide, and the former vary between 1 to 3 mra. 

 in height and in thickness. The grooves commence in the central 

 areas of both surfaces, and after a more or less sinuous course 

 converge, and become deeper and more distinct between the 

 lobes at the margin of the frond. There is no definite trace of 

 oscula, except a few scattered apertures or perforations be 

 regarded as such. 



Textuie hard, incompressible, and tough ; colour greyish- 

 yellow. 



Skeleton : — The central regions of the sponge consist of a 

 series of plexoid fibres, which are scai'cely distinguishable on 

 account of the large amount of spongin and the numerous scat- 

 tered spicules ; the secondary fibres are, however, very distinct ; 

 they are usually about 025 mm, in diameter and from 0*3 to 0*5 

 mm. apart. There is an axial core of closely arranged spicules ; 

 this is echinated with numerous others, which are disposed at an 

 high angle and terminate in radiating tufts at the surface. 

 Between the latter a few scattered oxea occur and are generally 

 disposed at right angles to the fibres. 



