) 
blue-greyish clay; there where specimens as in fig. 7 have been 
dredged up, the bottom was much more stony or sandy, thus more 
resising. Now it will be clear that the thin fibres can pierce 
the soft clay, but, forced to grow through a sandy substance with 
many little stones, it often will be necessary to change the direc- 
tion and often only a part of the bundle will find an outway. 
As is represented in figure 7 several of the little sand-partieles 
remain adhering at the fibres of the roots. 
Lastly we have to make mention of long bundles that are seen 
on the top of the Sponge. Sometimes these bundles are very long 
and slender (fig. 2), another time they are hardly conspicuous (fig. 1) 
or totally absent (figg. 5, 6 and 7). 
In comparing this description and the figures 1—7 with those 
given by Bowerbank in his „Contributions to a General History of 
Sponges” !) of his Tethea muricata, with Wyville Thomson’s Tisi- 
phonia agariciformis ?) and with Oscar Schmidt’s Tisiphonia fene- 
strata °), then it will be clear that there is to be seen a remarkable 
resemblance between all those Sponges. I hope to show that it 
is only one species with rather numerous variations! Schmidt 
was the one of the first Spongivlogists who demonstrated the possi- 
bility ofsuch great variations. Now anatomy proves to us the near 
relation between Tethea muricata, Tis. agariciformis, Tis. fenestrata 
and our Sponge. I regret it very much that the material is not 
sufficient for histological researches; I could not become acquainted 
with the whole system of canals. 
As I have said in my preface, one must distinguish two kinds 
of spicules, viz. those that are always abundantly present and 
those that are very rare or present in one individual and in the 
other absent. In other terms: spicules that are characteristie for 
the species, and spieules that are of less importance, and that at 
most may serve as distinctions for varieties. 
1) Proc. Zool. Soc. 1872 pagg. 115—118, plate V fige. 1—6. 
2) Depths of the Sea pag. 188. 
3) Spong. Meerb. Mexico, Pl. X. fig. 2 a,b, ee. 
