772 



MR. A. G. THACKER ON 



[June 16, 



Leucandra verdensis, sp. n. (Plate XL. fig. 6 & text-fig. 163.) 



The collection contains only a single specimen of this species. 



It was dredged from a depth of 10 fathoms and is a single Leucon 



person of sac-like form, nearly cylindrical in shape (Plate XL. 



fig- 6)- 



The length of the specimen is 6 mm. and its maximum width 

 3 mm. There is a terminal osculum which is naked and the 

 surface of the body is smooth. The thickness of the body- wall is 

 about 1 mm. and the diameter of the central gastral cavity is 

 about the same. The colour of the sponge (in spirit) is brown. 



Text-fig. 163. 



Spicules from Leucandra verdensis. 



a = Parenchymal triradiates. h = Regular triradiates of dermal cortex, c = Sagittal 

 triradiate of dermal cortex, d = Gastral quadriradiate. e = Gastral tri- 

 radiate. All X 120. 



The canal- system is typically leuconoid ; the flagellate chambers, 

 which are scattered about in the parenchyma between the dermal 

 and gastral cortices, are spherical or sac- shaped and have a 

 maximum diameter of about 0*06 mm. 



The dermal cortex, which is pierced by passages leading into 

 large inhalent canals, is only about 0'02 mm. thick ; and the gastral 

 cortex, which is similarly pierced by apertures leading from the 

 exhalent canals, is of about the same thickness. 



The Skeleton consists of triradiates and quadriradiates. There 

 ai-e no oxeote spicules. 



The main mass of the skeleton, that of the chamber-layer, con- 

 sists of numerous large, irregiilarly arranged, regular or sub- 

 regular triradiate spicules (text-fig. 163, a). They do not vary 



