Mr. H. J. Carter on the Genus Rossella. 115 
sponding with the long transverse diameter of the body 
(fig. 5, a), leadimg into a cavity of much the same shape as 
that of the sponge externally (fig. 4,ee). Sessile or fixed by 
anchoring-spicules. Colour grey. External surface uniformly 
eribellate and monticular, covered by a thin layer of spicular 
latticework, and surmounted by three forms of projecting 
spicules situated respectively on the truncate end, on the body, 
and on the conical end, as will be more particularly described 
hereafter. Internal surface, or that of the cavity, uniformly 
smooth, interrupted by depressions or pits increasing in size 
towards the lower part. Body or wall constructed of a dense 
interlacement of large and small spicules, rendered more solid 
and areolar by the addition of sarcode charged with the minute 
spicules of the species, and accompanied throughout by the 
ramifications of the excretory canal-system. Layer of lattice- 
work formed of minute, sexradiate, spimiferous spicules, whose 
horizontal arms, spreading out at right angles to and over- 
lapping each other, form a quadrangular retiform structure 
held together by the dermal sarcode. Pores situated in the 
sarcode fillmg the quadrangular spaces of the latticework. 
Vents opening into the pit-like depressions on the surface of 
the cavity. Spicules of three kinds, viz. appendicular, struc- 
tural, and flesh-spicules. A. Appendicular, of three forms, 
corresponding with their respective localities :—1. That con- 
stituting an erect beard, about a quarter of an inch long, situ- 
ated round the aperture (fig. 4, c), stout, linear, smooth, nearly 
straight, fusiform, acerate, finely pointed at each end, averaging 
10-12ths by 8-1800ths of an inch in its greatest diameters. 
2. Anchoring-spicule, which issues from the surface of the 
body generally, beginning very scantily above in little groups 
here and there, which increase in number, size, and length 
towards the lower or conical end, where they attain their 
maximum size and density (fig. 4,7 d): stout, smooth, linear, 
commencing in a finely attenuated end which is fixed in the 
sarcode of the body, and gradually passing into a thick shaft 
which is abruptly terminated at the free end by four opposite, 
stout, recurved spines or hooks (fig. 8); average largest size 
3 to 4 inches by 5-1800ths of an inch in its greatest diameters, 
hooks 30 by 5-1800ths of an inch. 3. Crucially headed or 
veil-spicules, projecting chiefly from the monticules, over every 
part of the external surface but the aperture, consisting of a 
shaft whose pointed or inner end is fixed in the sarcode of the 
body, and whose free or outer one is terminated by four long 
arms spread out horizontally so as to intercross with those of 
its neighbours, and thus form a general veil-like covering 
separated from the body by the length of the shafts between 
: ge 
