0f a <^|r 0 tt 90 . 
By Professor W. J. SOLLAS, M.A., F.R.S.E., 
F.G.S., &c. 
The presentation of a tolerably complete account of any single 
species of sponge is a matter of considerable difficulty, since, not- 
withstanding the existence of many hundreds of species of sponge, 
which have been made known to us by excellent figures and des- 
criptions, there is not one of which the complete life-history is 
known. That of which the history makes the nearest approach to 
completeness is the calcareous sponge, now known to naturalists 
under the name of Sycandra raphanus. 
Gejieral Form . — This little sponge, not more than 3 or 4 mms. 
{i.e. i of an inch) in height, presents us with a variety of forms, 
being sometimes spindle-shaped, sometimes ovate, at others, turnip- 
shaped, and occasionally almost spherical. Sometimes it is 
supported on a short stalk, and sometimes it has no stalk, or 
is sessile. Internally it is hollow, like a sac, the walls, or sides 
of the sac, being 2 mms. thick, and the internal cavity about 2 
mms. across. The sac is closed below, but opens above by a 
circular or elliptical mouth, which is surrounded by a graceful 
fringe of slender needle-shaped spicules, composed like the rest 
of the spicules of the sponge, of carbonate of lime, and an 
organic substance known as ‘ spiculin.’ 
The spicules of the fringe, or corona, are sometimes seen in 
movement, now diverging from each other till they give to the 
corona the form of an inverted cone, and again approaching one 
