Knowledge of the Spongida. 109 
with its filamentous surface and the fibrillous composition of 
the fibre after exposure. 
Aplysina compacta, n. sp 
There is still another specimen from the south-west coast 
of Australia in the Bowerbank collection, which, although 
much worn and only 2} inches in diameter each way, bears 
evidence of an altogether different species. The mass in 
form is irregularly lobed; black in colour, with an irregular 
although smooth surface; the sarcode charged throughout 
with intensely black-purple pigmental cells, and the fibre 
small, short-meshed, reticulated, and abundant, so that the 
internal structure is more compact than cavernous. On 
account of its massive amorphous state and the granular core 
of the fibre prevailing greatly in size over the thickness of its 
horny investment, I have named it “Aplysina;”’ but other- 
wise the fibre, from its uniformity in size and short uniform 
reticulation, yellow colour when denuded of the black sareode, 
and great abundance, simulates that of Luffarta; so slightly 
do some of the. species of these families differ from each other! 
Family 3. Pseudoceratida. 
Here I must at once correct an error which partly led me 
to propose the formation of this “ family,” viz. the impression 
that an Aplysian fibre internally might be combined with a 
spiculiferous one on the surface; hence I named the supposed 
species “ Aplysina chalinoides,” gave this as part of the 
character of the “family” (‘ Notes’ &c., loc. cit. p. 132 
&e.), and placed it among the typical illustrations (¢bed. 
p- 192); but on examining it more particularly I found out 
that it was a tubular digitate Chalina, in which the acerate 
spicules of the fibre eternally had become absorbed, leaving 
a granular axial tube or core with horny exterior, of a dark 
amber-colour, exactly like that of Aplysina, while the small 
fibre of the surface still retained its spicules. Hence ‘“Aply- 
sina chalinoides”’ must be expunged, as well as that part of 
the character relating to it, in the diagnosis of the Pseudoce- 
ratida (loc. cit.), viz. “‘or passing into a dermal layer of 
proper spicules like that of the Rhaphidonemata,”’—a mis- 
leading change, which is not confined to one species of 
Chalina only, but may occur in others of a similar kind, and 
has thus been mentioned to prepare the student for dealing 
with it accordingly. 
