R. W. H. ROW—REPORT ON THE SPONGES: NON-CALCAREA. oat 
length of 25 mm. or even 30 mm. The largest complete specimen in the 
collection measures 120 mm. in length, 45 mm. in breadth, and 55 mm. high 
to the summit of the processes. | 
The surface of the sponge is smooth and even, and no reticulation can be 
seen on it. Under the microscope it is very minutely hispid, owing to the 
projection of spicules from it. 
The oscula are confined to the summits of the processes above described 
and are very small. When widely open (at any rate in my specimens) they 
do not exceed 0°8 mm. in diameter, and in most cases they do not measure 
more than 0°3 mm. to 0°5 mm. <A few of them are completely closed and 
invisible, the process being lipostomous. The pores are exceedingly minute 
and are scattered all over the sponge-surface. 
The colour is a dull yellowish grey, due doubtless to a large extent to the 
great quantities of mud the sponge has engulfed. 
The texture is very lax and soft, and the whole sponge is very fragile and 
easily broken. 
Skeleton arrangement, 
The skeleton consists almost entirely of rather sparsely and quite irregularly 
scattered tylostyles, but here and there occur slender 
A . : o8 
h spicular fibres, composed of spicules exactly similar to 
y) A those scattered throughout the sponge. ‘These fibres 
uf iM run irregularly in the sponge-body, even in the pro- 
cesses, but, as a rule, they tend toward the surface 
and finally project from it. In the processes they 
B also run more or less longitudinally. The number 
of rows of spicules composing them varies from 3 in 
\ small fibres to 6 to 8 in the largest. 
Tiree 17 : 
Esperella Jistulifera. Spicules. 
Microscleres : 
: A. Megascleres. 
eat ao aa The only megascleres which occur in this sponge 
are sub-tylostyli. They are very slender and always quite straight. The head 
is small and oval, and has its longest axis a continuation of the axis of the 
shaft of the spicule. The average length of the spicule is 0°25 mm. The 
thickest part of the shaft is close to the head ; from these the spicule tapers 
very gradually to a very fine point. The diameter of the spicule is about 
0-002 mm. at the thickest point, and that of the head 0:0025. 
B. Microseleres. (Text-fig. 17.) 
(i.) Chele. (Text-fig. 17, A.) 
The chelee are very small palmate anisochelee, which occur sparsely scattered 
about throughout the sponge. They do not form rosettes, nor are they more 
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