of the National Antarctic Expedition. 277 



bipocilla ai)parent]y of the typical form ; tlie present two 

 species botli have spathulate bipocilla with creuulated ends ; 

 and, fnvther, there are differences, viz. in the shape of the 

 body? the arrangement of the skeleton, and the character of 

 the ectosomal spicules, wliich lead me to regard the 

 ' Discovery ' specimens as belongino- to distinct species. 



Localities. Winter Quarters, 25-30 fath.; Coulman I., 

 100 fath. 



loplion Jlahello-digitatiis, sp. n. 



Sponge forming a large palmato-digitate or digitate growth 

 in one plane ; branches compressed, usually with oscules 

 along one edge. Surface finely verruculate ; with elongated 

 pore-areas supported by fan-like wisps of ectosomal spicules. 



Colour dark brown j consistence soft, the sponge being 

 readily broken. 



Skeleton typically formed of a network of spiculo-fibre, the 

 primary lines of which proceed upwards and outwards from 

 the inner surface of oscular tubes to the outer surface of the 

 sponge, where their ends form the verructe ; the secondary 

 fibres join the primary at right angles, forming rectangular 

 meshes about 1*25 mm. square. The thickness of the primary 

 fibres is about •? mm., that of the secondary about '5 mm. 



The ectosomal skeleton consists of fan-like bundles and 

 wisps of spicules, isolated or proceeding upwards and spreading 

 out from the terminal main fibres. 



Spicules. — Megascleres : smooth styles, 590 x 25 fx, curved, 

 with a mucro at the head end. 



Ectosomal spicules, 344x 12"0|a, subaniphitylote, fusiform, 

 with a marginal ring of vertical spines at both ends and a 

 terminal central spike at one extremity. 



Microscleres : palmate anisochelee of two sizes, a large 

 kind 35 fi long and 10'7 fi broad, with thick shaft, with 

 triangular palmate tooth, 17*5 /u- long, at the large end, not 

 quite as long nor as broad as the alas; lower margin of alas 

 convex. Lower central tooth with a curved upper edge 

 produced into a spine. 



A small kind, 11'5 fi long, 6*2 yw- broad; upper palmate 

 tooth triangular, rounded above, as broad and as long as the 

 ala? ; lower border of alte concave ; lower tooth with simple 

 rounded upper edge. 



Bipocilla varying in length from 5"5 to 11 //-, according to 

 the convexity of the shaft, which is usually deeply curved ; 

 both ends spathulate, nearly similar, and with creuulate 

 edges, or witli 5-7 teeth. 



