304 Mr. H.J. Carter on the Species, Structure, and Animaliiy 



bodies spherical, l-36th of an inch in diameter. Spicula of two 

 kinds, large and small ; large spicula smooth, slightly curved, 

 pointed at each end, 1-5 7th of an inch long; small spicula 

 smooth or thickly spiniferous, slightly curved or straight, 1 -200th 

 of an inch long. Transparent portions of investing membrane 

 abounding in the small spicula. 



3. Is of a light yellow colour, massive, spreading, convex, with 

 short irregularly formed conical projections on the surface, or 

 meandering ridges with sulci between them, attaining a thick- 

 ness of two inches; texture fine; structure fibrous, plumose, ob- 

 liquely reticulated towards the base, rectangularly reticulated 

 towards the circumference ; friable. Seed-like bodies spherical 

 and l-40th of an inch in diameter. Spicula of two kinds, large 

 and small; large spicula smooth, slightly curved, pointed at 

 both ends, 1-5 7th of an inch long; small spicula composed of 

 a straight portion, sometimes slightly spiniferous, terminated at 

 each end by a toothed disc with its points recurved or horizon- 

 tal ; the central portion is l-400th of an inch long, the discs 

 l-600th of an inch in diameter. 



4. Is of a bright yellow colour, massive, spreading, horizontal 

 on the surface, with projecting, plumose, irregular portions, at- 

 taining a thickness of about two inches ; texture coarse, loose ; 

 structure fibrous, branched, plumose, obliquely reticulated ; semi- 

 friable, may be compressed with the hand in water without under- 

 going much injury. Seed- like bodies ovoid, l-28th of an inch 

 in their long diameter, and l-50th of an inch in their short 

 diameter. Spicula of two kinds, large and small ; large spicula 

 smooth, shghtly curved, pointed at each end, l-66th of an inch 

 long ; small spicula l-300th of an inch long ; consisting of a 

 straight portion, terminated by a toothed disc at each end, with 

 its points recurved or horizontal, 1 -950th of an inch in diameter. 

 Transparent portions of investing membrane abounding in little 

 siliceous stellated bodies, their arms projecting from a central 

 cell, tapering to a point which ends in a stellated circle of re- 

 curved spines ; they are l-600th part of an inch in diameter. 



The measurements of the seed-like bodies and the spicula are 

 taken from the average size of the largest of their kind. 



Habitat. — On the inclined and under surfaces of rocks, or at- 

 tached to floating bodies in the tanks of Bombay ; never at the 

 bottom, and sometimes so high up as to be only covered by water 

 three or four months in the year. 



Investing membrane. — The investing membrane of the Fresh- 

 water Sponge, like the skin and the mucous membrane in the 

 human body, is continuous throughout ; and, like a shut sac, 

 surrounds the parenchymatous structure and spicular skeleton of 

 the whole mass, without inclosing it. In some instances it 



