X PEEFACE. 



On the Gregarince see in addition Leon Dufour Ann. des Sc. nat. xiir. 

 pp. 366—368 ; FfiANZiua Observationes qucedam de Gregarinis, Berolini, 

 1846, and in Wiegsiann's Archiv f. Naturgesch. xiv. s. 194, &c., Stein 

 in Mueller's Archiv, 1848, pp. 182 — 223, Koelliker in Koelliker u. 

 Siebold's Zeitschr. f. tcissensch. Zool. i. pp. 1 — 37, with a description of 

 many species, Leidig in Mueller's 4 rcAiV, 1851, Ueher Psorospermien u. 

 Gregarinen, pp. 221 and 223. 



Many authors are now disposed to refer the sponges to the ani- 

 mal kingdom. This opinion of Lamarck was afterwards sup- 

 ported by Grant, Me yen and L. Laurent, and to this conclusion 

 tend also the observations recently published by N. Lieberkuehn 

 on the development of the fresh-water SpongillcB. 



Sea-sponge {Spongia L.) consists of a loose, porous, horny mass, 

 formed of line unjointed, branching threads more or less trans- 

 parent. In fresh-water sponge [Spongilla lacustris) the frame-work 

 is formed of fine spicula in which a green granular mass is disposed, 

 whilst in this at certain times of the year small round masses are 

 seen, the so-named gemmules. These are cysts of spongillge ; when 

 the envelope bursts, the spongillar mass creeps forth and after- 

 wards develops tubular processes. Besides these there are ciliated 

 embryos, which after a while attach themselves and lose their cilia. 

 These yoimg spongillge soon develop a tubular process with an 

 aperture capable of being closed and opened. There are ova also 

 with a germinal vesicle and spot and spermozoid bodies which are 

 formed in fixed capsules. It seems uncertain where this addition 

 to the animal kingdom is to find its true relation. Doubtless it 

 has some analogy with the Rhizojjoda, pp. 45, 46. If the sponge 

 be not a colony but an individual, then the relation to the RMzo- 

 poda would be best illustrated by that between Actinia and Fungia 

 amongst the Anthozoa. Lamarck considered the sponges to be 

 colonies, polyparies with unknown inhabitants, and placed them 

 yf\\h Alcyonium (not to be confounded with Lohularia 1jA.M., Alcyo- 

 nium of recent authors) amongst the Folyjparia porosa or Polypiers 

 foramines. 



On the sponges may be cited : Lamarck Hist. nat. des Anim. sans 

 vertebres, 2e edit, par M. Deshayes et Milne Edwards, ii. pp. 529 — 590, 

 1836, Papers of Grant in the Edinh. Phil. Journal, xiii. p. 94, p. 333, 

 XIV. p. 113, p. 336, On spongia friabilis, XIV. p. 270, On Calcareous 

 Sponges, Ed. Phil. Journ. New Ser. i. p. 166, On Silicious Sponges, ibid, 

 p. 341, ffist. of British Sponges, by George Johnston, Edinb. 1836, 

 Meyen Beitrdge zur ndheren Kenniniss umcres sfiiss-wasser Schwammes in 



