94 Z. HYDROIDA. Hydra. 



Carus, Comp. Aiiat. tab. 1. fig. 1 H. viridissima, Pall. Eleiich. 31. 



Third sort of Polype, Baker, Polyp. 19 c. fig Le Polype vert, 



Cuv. Reg. Aiiim. iii. 293. L'Hydre verte, Blainv. Actinol. 494. pi. 



85, fig. 1. 

 Hab. 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, " 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 quartei'S 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 Gane 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 decouverte 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 formativus. 



