Mr. H. J. Carter on known Fossil Sponges. 281 
(p. 822). And, thirdly, that the quantity of the horny- 
fibred sponges, particularly from the sea on the south coast of 
Australia and that about the West-India Islands, in the col- 
lection at the British Museum, far surpasses all the rest in 
bulk and number of species. 
Here I must, for the sake of convenient reference, insert 
a note of my Classification of 1875 (‘ Annals,’ vol. xvi. p. 128 
&c.) — 
Class SPONGIDA, Huxley. 
Order I. Carnosa. 
Without evident skeleton. 
Order II. Ceratina. 
Possessing a skeleton composed of horny (now called 
“ spongin ”’) fibre, with a granular, chiefly hollow, core, con- 
taining for the most part no foreign bodies, 
Order III. Psammonemata. 
Possessing a skeleton composed of solid fibre more or less 
cored with foreign bodies (grains of sand, fragments of sponge- 
spicules, &c.). 
Order 1V. Rhaphidonemata. 
Possessing a skeleton composed of horny fibre with a core 
of “proper spicules” (that is, spicules produced by the 
sponge itself). Spicules chiefly simple acerate, and chiefly 
confined to the ¢nterior of the fibre. 
Order VY. Echinonemata. 
Possessing a skeleton composed of horny fibre cored with 
_ proper spicules” internally and echinated with ‘“ proper 
spicules ” externally. orm of spicule chiefly acuate. 
Order VI. Holorhaphidota. 
Possessing a skeleton whose fibre is almost entirely com- 
posed of ‘ proper spicules”? bound together with a minimum 
of sarcode (spongin). orm of spicule variable. 
Order VII. Hexactinellida. 
Possessing a skeleton charged with “ proper spicules,” all 
