490 PROF. A. DENDY AND MISS L. M. FEEDEMCK ON 
oval vents, 3"5 mm. in diameter, with slightly prominent margins, occur on 
one edge. Microscopic inhalant pores are thickly scattered over the smooth 
surface. Colour in spirit light greyish brown ; texture firm and compact. 
The skeleton consists of a thick feltwork of loose, irregularly arranged 
spicules. There is a dense layer of oxea at the surface, largely but not 
entirely radially arranged. 
Spicules : — (1) Tetracts ; -with smooth, sharp-pointed rays measuring from 
0'093 to 0'2 mm. in length and from 0"018 to 004 mm. in thickness. 
(2) Diacts (oxea) ; smooth, fusiform, slender, slightly curved, gradually 
sharp-pointed, sometimes with a kink or an enlargement near the middle, 
measuring from 0'06 to 0'14 mm. in length and from 0'004 to 0"005 mm. in 
thickness. The oxea are more numerous than the tetracts. Triacts are absent. 
The dermal pores lead into short, narrow, inhalant caiials piercing the 
densely spiculated ectosome, beneath which they unite to form sub-cortical 
crypts from which the inhalant canals of the choanosome originate. The 
canal system is diplodal, the aphodi and prosodi being longer and narrower 
than in Dercitopsis minor Dendy. The flagellate chambers are S!ib-s])]ierical, 
measuring about 0"04 ram. in diameter. The narrow exhalant canals gradually 
pass into wider ones, which in turn open into the wide oscular tubes. The 
main inhalant canals are surrounded by collenchymatous mesogioea devoid of 
spicules ; the main exhalant canals are probably like the inhalant, but as no 
sections have been taken through a vent this cannot be proved. The nieso- 
glcEa between the chambers is finely granular. 
Testes are irregularly scattered in the choanosome ; thev are rounded sacs 
lined by an epithelium and containing various stages in the development of 
spermatozoa. Segmenting embryos are also present ; the sponge is therefore 
hermaphrodite and presumably protogynous. 
Previously known Distribution. West coast of Australia (^Lendenfeld). 
Register No. and Locality. II. 13, Wooded Isle. 
13. Stelletta BEEVis i/ewi^c/teZ [1909]. 
The single specimen, a cushion-like mass which has probably been torn off 
a rock, measures 38 mm. in length, 25 mm. in breadth, and 15 mm. in 
thickness. Surface smooth but finely granular. Oscula not visible. The. 
surface colouring in spirit varies from a very light brown to a violet-grey, 
that of the interior is light brown. 
The sponge possesses a well-developed cortex. Immediately beneath the 
surface is a thin layer of strongylasters, then comes a non-fibrous portion 
filled with minute brown pigment granules and containing inhalant chones ; 
below this is a light-coloured, non-pigmented, fibrous layer. Between the 
cortex and the choanosome are large sub-cortical crypts. The choanosome, 
in which oxyasters are thickly scattered, contains narrow inhalant 
canals. 
