to our Knowledge of the Spongida. 
299 
Chondritta sacciformis. (PI. XXVI. figs. 9, 11, and 12.) 
Saccular and cylindrical (PI. XXVI. figs. 9 a, 9 a), or ad- 
nate and depressed (fig. 9 h) ; sessile, corticate. Colour dark 
brown. Texture stiff and hard externally, soft internally 
when dry, chondroid and flexible when wet. Surface even, 
formed of the globular spicules (fig. 12) arranged in a tessel¬ 
lated manner like shagreen. Pores uniformly present all over 
the surface between the globular spicules, provided respec¬ 
tively with a sphinctral diaphragm of sarcode, l-164th inch 
in diameter and a little wider apart. Vents single and large 
at the end of the sacciform growth (figs. 9 a, 9 a), or nume¬ 
rous and scattered over the adnate portions (fig. 9, 5, c), pro¬ 
jecting and papillary when wet. Structure cortical and 
internal; cortex stiff and hard when dry, about l-138th inch 
thick, chondroid and flexible when wet, charged with the 
globular spicule and traversed by the canals of the pores and 
vents, respectively ending in their apertures on the surface ; 
internal structure compressible, tough, resilient, consisting of 
areolar sarcode charged with groups of brown pigment gra¬ 
nules (which give the colour to the sponge) and the spicules of 
the species, traversed by the branches of the excretory 
canal-systems. Spicules of two kinds, viz. :—1, skeleton-, 
acerate, smooth, curved, sharp-pointed gradually, l-25th by 
l-900th inch in its greatest dimensions (fig. 11); 2, flesh- 
spicule, spherical, globo-stellate, moriform, 1-225th inch in 
diameter (fig. 12) ; granules arrangedhexagonally (fig. 12, a), 
conoid, truncate, and spined over the extremity (fig. 12, b) } 
or simply conoid (fig. 12, c). No. 1 (spicule) is confined to 
the internal structure, mixed with no. 2 in different stages of 
development; no. 2 in full development, exclusively to the 
cortex. Size of largest sacciform portion about 1^ inch long 
by | inch in diameter, that of the adnate portions various. 
Hob. Marine, on hard bodies. 
Loc. Mauritius. 
Obs. Examined in the dried state and after soaking in 
water. In the former it is stiff, hard, and corrugated, while 
in the latter it is soft, flexible, and smooth. The globo-stel¬ 
late or moriform spicule, although a strikingly beautful object 
in situ, and separate from its great size, is but an enlarged 
form of that of Chondrilla nucula , Sdt., which, together 
with Chondrosia , Nardo, also occurs at the Mauritius. C. 
nucula also grows in the West Indies and at the Molucca 
Islands, in the South Pacific Ocean, so that it probably has a 
world-wide extension in the warmer climates. The presence 
of the acerate spicule makes it differ from Chondrilla nucula , 
