434 POLYPI. 
in the cavity of their body. They are sensible to the action of light, 
and seek it, but their most wonderful property is that of being con- 
stantly reproduced by the indefinite excision of their parts, so that 
we can multiply them at will by means of division. Their natural 
increase is by shoots which push out from various points of the body 
of the adult, and at first resemble branches. 
Five or six species, all differing in colour and the nuutber and 
proportion of the tentacula, are found in stagnant waters in 
France. One of them, 
H. viridis, Trembl., Pol., I, 1; Roes., TI, Ixxxviii; Encyc., 
LXVI, is of a beautiful light-green. It is particularly common 
under the leaves of the Lemne, and has been rendered cele. 
brated as the first species on which the experiments relative to 
the reproductive power of the genus were essayed. ‘The 
H. fusca, Trembl., Pol., I, 3, 4; Reoes., III, lxxxiv; Encyc., 
LXIX, is more rare, and ofa grey colour. Its body is not above 
an inch long, and its arms are more than ten*, 
Corine, Gert. 
The Corines have a fixed stem terminated by an oval body, of a 
firmer consistence than that of the Hydrz, open at the summit and 
completely covered with little tentacula. Some of them carry. their 
ova at the inferior part of the body t. 
CrisTATELLA, Cuv., 
Where there is a double range of numerous tentacula on the mouth, 
curved into a half moon, forming a plume of that figure, which at- 
tracts the nutritious molecules by their regular motion. These 
mouths are placed on short necks attached to a common gelatinous 
body which progresses in the manner of a Hydra. These animals 
are found in stagnant waters in France. To the naked eye they 
seem to be small spots of mould f. 
VoRTICELLA, 
Where the stem is fixed, frequently ramous and much divided, each 
branch terminating by a body shaped like a bell or horn. From the 
aperture project two opposing groups of filaments which are con- 
stantly in motion, and that attract nutritious molecules. The species 
* Add Hyd. grisea, Trembl.,1, 2; Rees., III, Ixxviii—lxxxiii; Encye., LXVII; 
—Hyd. pallens, Res. ; U1, Ixxvi, xxvii; Encye., LXVIII ;—Hyd. gelatinosa, Zool. 
Dan, CAV, 1, 2: 
N.B. The ten first Hydre of Gmelin are Actiniz, and the eleventh—H. doliolum— 
a Holothuria. 
+ Tubularia coryna, Gm.; or Coryne pusilla, Gert., App. Pall. Spicil., X, iv, 8; 
Encye., LXIX, 15, 16 ;—Tubularia affinis, Gm.; Pall., Ib., 9; Encyc., Ib., 14;— 
Hydra muiticornis, Forsk., XXVI, B. b; Encye., Ib., 12, 13 ;—Hyd. squamata, 
Miill., Zool. Dan., IV; Encye., Ib., 10, 11;—and the species sketched by Bosc., 
Hist. des Vers, II, pl. xxii, f. 3, 6, 7, 8. 
N.B. The genus Corine, which I have not observed myself, appears to merit re- 
examination. , 
t Cristatella mucedo, Cuy.; Rees., III, xci. 
