74 CLASS II. 



HOES. Ins. in. Polyp. Tab. 84, 85, 87 \ TREMBLEY performed most 

 of his experiments on these last two species. Comp. what is said 

 at pp. 67, 69. 



On this genus compare the work of TREMBLEY, noted in p. 60, and of 

 LAURENT, p. 68. The first discoverer of the genus was LEEUWENHOECK, who 

 probably observed Hydra grisea. He announced this animal in a letter to 

 the Royal Society of London, of Dec. 25, 1702, observed its propagation 

 by gemmation, figuring it with two young ones, and especially described 

 the great contractility of the arms. Phil. Trans. No. 283. Vol. XXIII. for 

 the years 1702, 1703, pp. 1304 1311. This description, however, had 

 been forgotten when TREMBLEY discovered the animal a second time. 



Clava GMEL. Coryne of authors, not of GAERTN. Body cla- 

 vate. Tentacles scattered. 



These animals are marine, and adhere to different bodies. Propa- 

 gation is effected by buds of a round or bell-shaped form, which 

 contain ova or spermatozoa, and which occasionally detach them- 

 selves from the stem on which they were developed, swim freely 

 about, and resemble small Medusae. 



Sp. Clava parasitica GM., Hydra multicornis, FORSKAL, Icon. Rerum natur. 

 Haunice, 1776. Tab. xxvi. fig. b, B. Cor. squamata MUELL. Zool. Danic. Tab. 

 IV. about three lines, according to RATHKE, inch long. RATHKE dis- 

 covered Spermatozoa in the swellings called Squamce by MUELLER ; vid. 

 WIEGMANN'S and ERICHSON'S Archiv. f. Naturgesch. 1844. s. 155 165 ; 

 Ann. des Sc. Nat. $*& Strie. n. 1844. Zool. pp. 201 210; WAGNER found 

 eggs in these swellings, Icon. Zootom. Tab. xxxiv. fig. 16. Thus the sexes 

 appear to be distinct. 



Eleutheria QuATREFAGES. Body hemispherical, hollow. Ten- 

 tacles six, divided into two retractile branches, terminating in a 

 round head. Six eyes placed at the base of the tentacles. 



Sp. Eleutheria dichotoma, DE QUATREFAGES, Memoire sur VEleutherie dicho- 

 tome. Ann. des Sc. not. sec. Serie. Tom. xvn. 1842. Zool. pp. 272 288, 

 PI. vui. Discovered in the Atlantic ocean, on the shore of the Islands 

 Chausey, Dep. La Manche, % millim. in diameter. There were eggs in the 

 posterior part of the body. This form is probably a free bud for the propa- 

 gation of some species of Coryne, Sertularia or Tubularia. See V. BENEDEN, 

 Bulletin deVAcad. Royale de Bruxelles, Tom. xi. No. 10. QUATREFAGES, ib. 

 Tom. xn. No. i. 



[Genus Pedicellaria MUELL. delendum 1 .] 



1 Pediculated organs with three valves are found between the spines and tentacles, 

 or suckers, of the sea-urchin, which MUELLER took to be parasitic Polyps, and of which 

 he formed the genus Pedicellaria. 



