S 
or broad as in figg. 1 and 5; it may happen that they are very 
indistinet as in figg. 2 and 3. It is very probable that this ceurious 
apparatus shows us a special organ for the entrance of the water. 
In specimens where the split is large it is covered with a thin mem- 
brane containing thousands of little pores. Thus this membrane 
represents a sieve. It seems to me that all the different specimens 
only represent one species but in a varying state of contraction. I 
suppose that the living Sponge can shut and open this penthouse- 
apparatus; so the second figure whould be the contracted state of 
fig. 1. I have tried in vain to study the living Sponge; during 
my stay at Naples no Thenea was dredged up. Anybody that 
has studied a living Tethya Iyncurium will agree that my suppo- 
sition is not improbable. | 
As I only have seen specimens preserved in alcohol, I can’t 
tell what has been the colour of the Sponge in its living state; 
-the specimens of the Barents Expedition are greyish or olive-co- 
loured. 
The surface of the Sponge is occasionally very hispid by the pro- 
truding spicules, but not always so. Bowerbank is quite right in 
saying that this „hispidation of the surface of the Sponge is not apparent 
to the (naked) eye, but is readily sensible to the touch of the fin- 
ger!). A comparison of the figg. 1—S plate I may show the 
different hispidation. The little light-greyish specimens are the less 
hispid. 
The roots of the Sponge consist of bundles of flexible long spi- 
cules, held together by soft sponge-substance. There may be one 
or more roots; in the latter case there can be one great thick root 
and several ihinner ones, but it also happens that all the roots 
have nearly the same value. One time the roots are not or little 
branched (fig. 1—6) another time they end in numerous thin fibres 
(fig. 7). Perhaps this difference has some relation with the consti- 
tution of the bottom of the sea. In the localities where specimens 
as in figg. 1, 2 and 3 have been found, the bottom consists of soft 
1) Bowerbank, Prov. Zool. Soc. 1872 pag. 116. 
ae 
