94 
Z. HYDROIDA. 
Hydra, 
Cams, Comp. Anat. tab. 1. fig. 1 H. viridissima, Pall. Elench. 31. 
Third sort of Polype, Baker, Polyp. 19 c. fig Le Polype vert, 
Cuv. Reg. Anim. iii. 295. L’Hydre verte, Blainv. Actinol. 494. pi. 
85, fig. 1. 
Hah. Ponds and still waters, common throughout England, and 
the south of Scotland. In almost all the parishes in the vicinity of 
Glasgow, Ure . 
The polypes of this species differ from the following, te not only 
in colour, but likewise in their arms, which were much shorter in pro- 
portion to their bodies, capable of but little extension, and narrower 
at the root than the extremity, which is contrary to the other spe- 
cies. Their arms were so short, they could not clasp round a very 
small and slender worm, but seemed only to pinch it fast, till they 
could master and devour it, which they did with as much greediness 
as any. I imagined these polypes owed their green colour to some 
particular food, such as weeds, &c. and that they would lose it upon 
being kept to worms ; but I find myself mistaken, for they retain 
their greenness after some months as well as ever, and are now grown 
of a moderate size, extending sometimes three quarters of an inch ; 
their arms are also lengthened very much to what they were, and 
are of a lighter green than the body, their number eight, nine, or ten. 
The tail is very little slenderer than the body, but more spread at 
the end than the tails of other kinds.” — Baker . 
Pallas says that the offspring are produced from every part of the 
body, while Blainville thinks he has remarked that they shoot always 
from the same place, “ au point de jonction de la partie creuse et de 
celle qui ne Test pas.” Blainville is candid enough, however, to in- 
form us that Professor Van der Hoven had made some observations 
adverse to his opinion ;* and our own are certainly in accordance 
with those of Pallas and of the Professor of Leyden. 
Trembley is careful to tell us that he discovered this species in 
June 1740, nor can we smile at the particularity of the record when 
we remember that the discovery is the foundation of his immortal 
fame.f It was first observed in England in the spring of 1743 by a Mr 
Du Cane of Essex. It appears to be a hardy animal. I have kept it for 
more than twelvemonths in a small vial of water unchanged during 
the whole of that time, and it remained lively, and bred freely, feed- 
ing on the minute Entomostraca confined with it, and which propa- 
* Bulletin des Sc. Nat. xvi. 337. 
f “ Trembley (Abraham), de Geneve, ne en 1710, mort en 1784; immortel 
par le decou verte de la reproduction du polype.” — Cuvier, Reg. Animal, iii. 422. 
■ — Blumenbach also informs us that his observations on this polype first led him 
to his ingenious investigations on the Nisus forniativus. 
