328 
THE VOYAGE OF H.M.S. CHALLENGEK. 
vasiform specimen measures 113 mm. in diameter across the brim, and 113 mm. in 
height ; the central cavity is 75 mm. deep. 
Habitat. — Japan, Misaki, at the entrance of the Bay of Tokio (Carter). Island of 
Enoshima, Bay of Sagami, Japan ; depth, 30 to 60 fathoms (Doderlein). 
Discodermia dissoluta, 0. Schmidt. 
Discodermia dissoluta, 0. Schmidt, Spong. Meerb. Mexico, p. 87, pL v. fig. 2, 1880. 
Sponge. — Branching, branches cylindrical, but flattened on the side bearing the 
oscules. Oscules several, confined to one side of the sponge, situated near the ends or 
in the middle of the branches, or in the angle between them ; small, surrounded by a 
smooth membrane, which is slightly depressed below the general level of the sponge, and 
forms the roof to a widely extending, shallow cloaca, into which numerous small ex- 
current canals open. Pores simple, small, 0‘019 to O'l mm. in diameter, generally 
distributed. Consistence soft, like that of a Eenierid sponge. 
Spicules. — I. Megascleres. 1. Desmas, precisely similar to those of Theonella 
swinhoei when immature, at a stage immediately preceding the appearance of syzygial 
tubercles. The epactines are united by plate-like extensions between the angles they 
make about their origin. They terminate in flattened plate-like ends, or in two or more 
flattened cladi, without giving rise to tubercles ; zygosis is of the loosest description, 
produced by the abutment against each other of the ends of the desmas. 
Here and there desmas are met with in which the epactines are cylindrical, and 
provided with syzygial tubercles. The crepidial axis is variable in length, frequently 
0'06 mm., the length of the epactine varies from about 0‘Q8 to 0T6 mm. 2. Disco- 
trisene, cladome disciform or cyathiform, margin usually entire, seldom presenting a 
rhabdal sinus ; 0’26 mm. in diameter, when cyathiform the depth of the cup 0’065 mm., 
rhabdome conical, strongylate, 0T18 by 0 '0118 mm. The axial fibres of the cladome 
0*02 mm. long. 3. Oxea, 0*8 by 0*1 mm., frequently tornotate, or strongylate. 
II. Microscleres. 4. Microxea, fusiform, surface roughened, very variable in size, 
up to 0*05 by 0*004 mm. 5. Microstrongyle, bacillar, surface roughened, 0*0118 to 
0*016 mm. long. 
Colour. — Dark greyish-white. Size, the length of the largest specimen, which is 
not complete, is 78 mm., diameter of the stem 15 mm., the branches are 10 mm. thick 
from the oscular to the opposite surface, and 18 mm. wide. 
Habitat. — Barbados ; depth, 56 fathoms. 
Remarks. — No one by merely looking at this sponge and handling it would suspect 
its Lithistid nature. So far from being of stony hardness, it is almost as soft as a bath 
sponge. This is due to the general absence of zygosis, the desmas having apparently 
