456 
roundish appearance; ca. 25X l5x 15 mm. Dermal-membrane very 
delicate, pierced by small, numerous ostia, ca. 0,i5 mm in dia¬ 
meter; oscula situated at one side, ca. 2 mm in diameter, sur- 
rounded by a low crater wall; cloacal cavilies ca. 2 
mm in width. Surface slightly granulose, on account of 
the numerous primary fibres raising the dermal-mem¬ 
brane. Texture soft, elastic. Colour light grey or yel- 
lowish. 
Skeleton consists of an irregular reticulation of fibres 
up to ca. 100 // thick; one can scarcely distinguish 
between primary and secondary fibres; only just be- 
neath the surface are fibres to be discerned running 
distinctly perpendicularly towards the surface, raising it 
into the before mentioned small granules. Width of 
meshes varying about ca. 250 /a. The fibres contain 
only comparatively little spongin; the spicules in the 
outer layer are often almost free from spongin, which 
I is, besides, very pale and difficult to observe; thus the 
\1 / spicules are everywhere forming the greater part of 
the fibres. Many spicules, especially developmental 
forms, are lying scattered in the choanosome between 
the fibres. No special dermal-skeleton is to be seen. 
Spicules. Oxea (fig. 14), ca. 120x g—lO //; they 
are slightly curved, the grown-up spicules cylindrical, 
tapering in the last fourth into the sharp points. 
This species comes very near to Pachychalina conica, though di¬ 
stinctly marked off from that species by the form of the spicules. 
Fig. 14. Pa¬ 
chychalina 
lunae nov. 
spec. Oxea. 
Tetrapocillon nov. gen. 
Esperellinae with peculiar microscleres (tetrapocilli). 
Megascleres monactinal. No special dermal-skeleton. 
Isochelae may occur. 
I propose to include in this new genus sponges with Esperelline 
skeleton possessing the very interesting and characteristical tetra¬ 
pocilli. I have not been able to find these peculiar spicules men¬ 
tioned anywhere in the literature. The following species is not 
unique; I have at my disposal a sponge from Port Western, Vic¬ 
toria, containing just the same tetrapocilli, and also in any other 
respect this sponge may be referred to the new genus; (I hope in 
