289 
to our Knowledge of the Spongida. 
waves, and washed about on a beach, perhaps for years, before 
it is picked up for our museums, as most of the sponges in 
our collections are and must necessarily be from their inac¬ 
cessible habitations, it may be easily conceived how unsatis¬ 
factory species-descriptions of a great number of specimens 
must indefinitely remain. 
The rigid, aculeated surface, the soft opaque granular cha¬ 
racter of the areolar sarcode, the hard chondroid tissue of the 
fibro-skeleton, and the spiculation generally, although slightly 
modified in form, ally this sponge equally to Axos Cliftoni 
and A. flabelliformis , while the thick fibrous cortex and general 
solidity of the body constitute differences as great as they are 
peculiarly characteristic, so far as is known, of Axos spini- 
poculum. 
The colour of the surface is now dark grey, as above stated, 
while that of A. Cliftoni and A. flabelliformis in the dried 
state respectively is white ; but as Mr. Clifton has observed 
that 11 when alive ” the former is u light red,” this also may 
have been the case with A. spinipoculum ; for it is worthy 
of notice that Donatia (olim Tethya) lyncurium , whose gene¬ 
ral structure and chondroid cortex closely resemble those of 
A. spinipoculum , is also light or orange red when alive, 
whether the specimen be British, Cape, or Australian, but 
loses this colour and becomes white or grey -when dried or 
kept in spirit. 
We thus analogically meet with the chondroid cortex of A. 
spinipoculum , so far as its cartilaginous nature goes, in Do¬ 
natia lyncurium , which is also so nearly allied to the genus 
Axos in most other respects, that it seems necessary to place 
the latter in a neighbouring group. When portions of A. 
spinipoculum are dried, the cortex and skeleton assume the 
consistence and colour of dried glue, which is just the case 
with Donatia lyncurium under similar circumstances. 
Nor should the striking likeness that exists between the 
aculeated surface of A. spinipoculum and the coarser forms of 
Hircinia pass unmentioned, from which, until the former is 
minutely examined, it might be very easily taken for the 
latter. 
Another very striking character presents itself in the canals 
of the excretory system in A. spinipoculum , by which they 
are immediately distinguished from the branches of the chon¬ 
droid skeleton in the midst of the areolar sarcode, viz. the 
transverse folds or rugae , already described, which, but for the 
means of touching the branches (say with the point of a 
needle) when a section of the sponge is examined under 
water, would be sure to be taken for branched canals through 
t O 
