Mr. J. Hogg on the Horny Sponges. 3 



II. — Remarks on the Horny Sponges, ivith proposed divisions 0/ 

 the Order Spongiae. By Johx Hogg, Esq., M.A., F.R.S., 

 F.L.S., &c. 



To the Editors of the Annals and Magazine of Natural History. 



Gentlemen, 

 Mr. Bowerbank ha\'ing published some very interesting 

 ' Observations on a Horny Sponge from Australia,^ at p. 

 129 of the 'Ann. and Mag. of Nat. Hist.' for April 1841, I 

 am induced to trouble you with a few remarks upon them. 



The author there writes, " that, contrary to received opi- 

 nions, they" (horny sponges) " are furnished with siHceous 

 spicula." This opinion, however, Mhich seems to me to have 

 originated from Dr. Grant's examinations of some of our Bri- 

 tish horny sponges, and from the statement which he has 

 made in the 'Edinburgh New Philosophical Journal' (forl827, 

 p. 122), where he says — "I have never observed any kind of 

 spiculum in the horny species," is incorrect as far as it relates 

 to all the horny, or subcorneous, sponges. Because, by re- 

 ferring to M. Lamarck's ' Hist. Nat. des Anim. sans Yerteb.,' 

 torn, ii., edit. 1836, p. 538, it will be seen that M. Milne 

 Edwards distinctly mentions some sponges which were de- 

 scribed by M. Savignyand figured in the plates of his superb 

 work on Egypt, as having " la disposition du reseau come et 

 des spicules qui constituent en quelque sorte la charpente de 

 ces corps." 



Now, since M. Milne Edwards has in the preceding page 

 (537) expressly said that "on ne connait pas d'especes qui 

 en presentent conjointement avec des epines calcaires et des 

 fibres cornees," it is quite certain that the " reseau corne et 

 des spicules" spoken of, and which were described by M. 

 Savigny, must signify the skeleton of a horny net-work with 

 siliceous spicula. Thus Mr. Bowerbank, by his late investi- 

 gations, has fortunately confirmed this fact ; and has disco- 

 vered the presence of siliceous spicula in some other species 

 of the horny sponges, which species were previously sup- 

 posed to be entirely destitute of them. But as it was like- 

 wise generally thought that the siliceous spicula seldom or 

 never put on more than tivo simple forms, it is of importance 

 to find from that author's papei' that he has proved the sih- 

 ceous spicula in the horny sponges which he examined to 

 exist under several different forms, some of which he has re- 

 presented in the accompanying figures, (Plate III. Vol. vii.) 



The next objects wortii especial notice in that paper are, 

 first, the reticulations of the transparent membrane. These, 



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