50 DR. J. E. GRAY ON IANTHELLA. [Jan. 14, 
This genus and the sponges which I described at a preceding 
Meeting under the name of Ceratella, &c., are peculiar in that the 
skeleton, though formed of a horny substance, is so dense that it 
does not, as in the generality of horny sponges, become softened and 
more flexible by being soaked in water; and, unlike the common 
sponges of commerce, they do not imbibe the water. But I suspect 
that many of the sponges with a hard, thick, black, horny network 
will be found to be unchanged by being soaked. 
There is no appearance of any pores for inhaling or oscules for 
emitting the water in the dry specimen. 
Being desirous of having it more carefully examined than the 
state of my eyes allows me to undertake, I sent a fragment of the 
specimen received from Capt. Sir Everard Home to Mr. M. C. Cooke, 
of the India-House Museum. He reports to me as follows :— 
1, That he has not been able to discover any trace of siliceous or 
calcareous spicules. 
2. It is dissolved away by acid. 
3. In liquor potass@ it gives a bright violet-colour, like that of 
Roccella and other orchil-lichens. 
TANTHELLA. 
Sponge frondose, expanded on a plane, flat, fan-like or funnel- 
shaped ; black, when dry more or Jess covered with dry, black, mu- 
cilaginous sareode, that often fills up the spaces between the horny 
network, and gives it a black polished appearance. Root expanded ; 
stem very thick, compressed, formed of interlaced filaments, ex- 
panded above into a broad flat frond entirely composed of rather 
thick, compressed, parallel ribs or branches, slightly diverging from 
the base towards the margin ; some of these are once or twice forked 
in their length. These ribs or branches are united into a network 
with a square mesh by very short, subcylindrical, thinner, equal- 
sized, diverging, compressed branchlets. 
* Frond flat, expanded. Janthella. 
1, IANTHELLA FLABELLIFORMIS. B.M. 
Sponge flabellate, expanded, oblong, fan-shaped, with a single 
thick stem; fibres of the network slender. 
Flabellum marinum, Rumphius, Herb. Amb. vi. 208, t. 80. f. 1 
(good), 
Spongia flabelliformis, Seba, Thes. ili. 183, t. 95. f. 2; Pallas, 
Zooph. 320; Lamk. Ann. Mus. xx. 380. n. 35; Esper, t. 13. 
Var. Network much finer. 
Spongia erecta subtilior, Seba, Thes. iil. t. 95. f. 4. 
Hab. Australia. 
The figure of Petiver (Gaz. ii. t. 32. f. 1) has been referred to 
this sponge ; but it is not a recognizable figure of it. 
