297 
to our Knowledge of the Spongida. 
Ohs. Examined in the dried state. This specimen had 
grown on a branch of decayed coral, and, from the quantity 
of sand in it, was probably picked up upon the beach. Its 
hemispheroidal form, long radiated laciniate structure, great 
length and projection of the long acuate, together with the 
light slate-colour mentioned, are its principal characters. 
It is also remarkable for the presence of a number of 
malformations of the long setaceous spicule, consisting of 
globular and elliptic bodies composed of concentric layers, 
thus traceable through their elongated forms into the normal 
development. Not an uncommon occurrence. 
Dictyocylindrus Pykii : n. sp. 
Subglobular, clathrous, massive, sessile. Colour dark pur¬ 
ple. Texture tender, loose. Surface uniformly composed 
of the ends of the clathrous structure. Pores and vents not 
seen, the latter for the reason just mentioned. Internally 
consisting of clathrous anastomosing branches, composed of 
indistinct fibre charged with the spicules of the species, and 
tympanized by the dark purple sarcode characteristic of the 
sponge. Spicules of three forms, viz.:—1, setaceous, acuate, 
curved, smooth, sharp-pointed, l-18th long by l-1800th inch 
in its greatest transverse diameter; 2, acerate, smooth, curved, 
sharp-pointed, l-50th by l-1800th inch in its greatest dimen¬ 
sions ; 3, ecliinating spicule, acuate, conical, straight, inflated 
at the base, subpointed at the free extremity, spiniferous, 
spines most numerous over the extremities, slightly recurved 
about the free end, l-272nd long by l-1500th inch in diameter 
at the inflated end, the same in form as the last (PI. XXVII. 
fig. 14). No. 1 projects obliquely upwards from the fibre, 
which is formed of no. 2, so as to give the surface of the 
clathrous structure a slightly setose character ; while no. 3 in 
great abundance forms the echinating spicule. Size of speci¬ 
men 3| inches high by 3 inches in diameter between the base 
and the summit, which is the largest part of the sponge. 
Hob. Marine, growing on hard objects. 
Loc. Mauritius. 
Ohs. Examined in the dried state. This sponge is chiefly 
remarkable for its deep purple colour, presenting, in this 
respect, the appearance of Mr. T. Higgin’s Halichondria 
hirotulata ; but the clathrate structure and echinated fibre, 
together with the spiculation generally, at once point out the 
difference. The indistinctness of the fibre in this and the 
foregoing described species is chiefly owing to the projection 
of the long setaceous and echinating spicules. Still there is 
a great difference between the loose and the compact structure 
