X PREFACE. 



On the Gregarince see in addition LON DUFOUB Ann. des Sc. not. xm. 

 pp. 366 368; FRANZIUS Observationes qucedam de Gregarinis, Berolini, 

 1846, and in WIEGM ANN'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. wissensch. Zool. I. pp. i 37, with a description of 

 many species, LEIDIG in MUELLER'S Archiv, 1851, Ueber 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 Spongilloe. 



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

 formed of fine 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 spongillae ; 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 young spongillae 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 Bhizopoda, pp. 45, 46. If the sponge 

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

 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 

 with Alcyonium (not to be confounded w r ith Lobularia LAM., Alcyo- 

 nium of recent authors) amongst the Polyparia porosa or Polypiers 

 foramin&s. 



On the sponges may be cited : LAMARCK Hist. not. cks Anim. sans 

 verttbres, 2e edit, par M. DESHAYES et MILNE EDWARDS, n. pp. 529 590, 

 1836, Papers of GRANT in the Edinb. Phil. Journal, xm. 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, Hist, of British Sponges, by GEORGE JOHNSTON, Edinb. 1836, 

 METEN Beitrdge zur ndheren Kenntniss un^ercs sitis-wasser Schicammes in 



