480 PROF. A. DBNDY AND MISS L. M. FREDERICK ON 
1. Leucosolenia grisea n. sp. (PI. 25. fig. 1 ; PI. 26. fig. J.) 
There are two specimens in the collection, the larger (R.N. VI. 21), which 
IS attached to a rock by its base, is plicate, consisting of vertical lamellai 
which fold and branch in such a way as to lie parallel to one another 
(PI. 25. fig. 1). The total height of the specimen is 30 mm., the total width 
25 mm., and the average thickness of the lamellse 1"5 mm. The second 
specimen (R.N. IV. 3 a) consists of a curved lamella, forming an imperfect 
funnel 20 mm. in height and 10 mm. in diameter at the top. 
The surface is smooth, even and sieve-like in appearance, owing to the 
pseudopores which are thickly and evenly scattered all over it. The oscula, 
which are marginal in position, are about 1 mm. in diameter and have a slightly 
prominent margin. Colour in spirit grey ; texture firm and compact. 
The pseudopores, which are nearly circular and measure about 0'26 mm. 
in diameter, pierce the pseudoderm, which is about 0"07 mm. in thickness, 
and lead into wide, irregular interspaces lying between the branching and 
anastomosing Ascon tubes. The prosopyles are accompanied by groups of 
black pigment granules which doubtless indicate the porocytes, as in the 
case of Leucosolenia coriacea as described by Minchin [1900], and in that 
of Leucosolenia cavata Dendy [1891] ; it is the presence of this jet-black 
pigment which gives the sponge its characteristic grey colour. The granules 
are not confined to the porocytes, but are also found scattered in the flat 
epithelium. The secondary Ascon tubes open into the main cxhalaut canals, 
which are also lined by basinucleate collared cells, and open to the exterior 
by true oscula. 
The canal system conforms to type B. (Deud}^ [1891].) 
The skeleton consists of triradiate and quadriradiate spicules arranged 
irregularly in one or more layers in the walls of the Ascon tubes ; the Iri- 
radiates are more densely packed in the thick pseudoderm. 
Spicules: — (1) Triradiates (PI. 26. fig. la); equiangular ; rays measuring 
about 0'14 mm. by 0'013 mm. ; straight, conical, rather bluntly pointed ; 
usually equiradiate, but the basal sometimes a little longer than the oral rays. 
(2) Quadriradiates (PI. 26. fig. 1 Z>) ; rather scarce, like the triradiates 
but with the addition of a long, slender, slightly curved and sharply pointed 
apical ray which projects into the gastral cavity. 
This species is readily recognised by its characteristic external form and 
its grey colour, due to the black pigment granules. 
Register Nos. and Localities. IV. 3 a. Wooded Isle ; VI. 21, Sandy Isle. 
2. Leucosolenia peotogenes Haeckel. (PL 25. fig. 2.) 
{For discussion and syuonymj' vide Dendy [1891].) 
There is in the collection a single small specimen (PL 25. fig. 2) of this 
common Australian species. 
Register No. and Locality. VIII. 4, Sandy Isle. 
