' 



• 



THE SPONGES. 



77 



which were collected at the same station with the Bathyxiplws, it is 

 probable that they belong to the former sponge. 



Bathyxiphus suhtilis F. E. Sch., the type on which the genus is based, 

 was taken by the " Albatross" south of Guadeloupe Island off Lower 

 California, Lat. 28° 57' N., Long. 118° 14' 30" 



W 



metres on a mud bottom. 



TRETODICTYIDAE F. E. Schulze. 



Hexactinella Carter. 



1885. Hexactinella Carter, 1885, p. 387. 



1887. Hexactinella Carter, Schulze, 1887, p. 328. 



Hexactinella labyrinthica, sp. nov. 



Plate 10, Figs. 6, 7; Plate 11, Figs. 1-7. 



Station 3405, 1 entire specimen and 3 fragments. 



Diagnosis. Sponge body a labyrinthine mass of branching and anastomosing flattened 

 or subcylindrical lobes. These are beset with numerous rounded oscula leading into short 

 cloaca-like main canals. The dermal skeleton includes pentacts, with more or less radially 

 disposed scopulae and roughened oxydiacts. The parenchymal microscleres are oxydiacts 

 and discohexasters. 



The entire specimen (Fig. 6, Plate 10) forms a he mi-spheroidal mass 

 which has a diameter of 60-80 mm., and is attached below to conglom- 

 erate. The lobes very commonly have a thickness of about 6 mm., and 

 the sponge has the appearance of having been produced by a continued 

 branching and anastomosing growth, which started from the centre of the 

 lower or attached surface. The oscula are about 2 mm. in diameter, are 

 bounded by a narrow border of oscular membrane, lie on the surfaces which 

 face outward, and are not on special elevations. The cloaca-like main 

 canals extend radially or obliquely into the interior for a short distance 

 only, 3 or 4 mm. Into them open numerous efferent canals. 



The surface of the sponge appears porous, owing to the very numerous 

 afferent canals, the outer ends of which abut against the dermal mem- 

 brane. The outer ends of these canals are in general rounded and vary 

 in size up to 1 mm. in diameter. The dermal membrane covering them 

 is riddled with pores (Fig. 7, Plate 11). In spots, especially in the neigh- 

 borhood of the periphery of the colony, where the lobes are attached to 

 the substratum, afferent canals large enough to be noted by the eye are 



■-■ 



V 



