136 



The following species of Hydra, was discovered too late to be 

 inserted in its proper place at page 11. 



HYDRAIDiE. 



Polypes gemmiparous, the young pullulating from the body 

 of the parent. 



HYDRA. 



Generic Character: Polypes locomotive, single, naked, 

 gelatinous, sub-cylindrical, but very contractile and mutable 

 in form, the mouth encircled with a single series of 

 granulous filiform tentacula. 



COMMON HYDRA. Hydra Vulgaris. Body gelatinous, 

 sub-cylindrical; tentacula seven to twelve, as long or longer 

 than the body. 



Hydra vulgaris, Ellis and Solander's Zooph., p. 9. Tur- 

 ton's Lin., vol. 4, p. 672. Stewart's Elem., vol. 2, p. 452. 

 Templeton in Mag. Nat. Hist., vol. 9, p. 418. Johnston's 

 Brit. Zooph., p. 95, pi. 1. 



Hab. In the Trengwainton ponds, near Penzance. Com- 

 mon. 



This, though a rare species in the country is common in all 

 parts of the ponds ; where it is to be found on Nitella trans- 

 lucens and other weeds growing there. If the usual des- 

 criptions of this Hydra are characteristic of its appearance, 

 it would seem as if the one now under consideration was a 

 distinct species. As, however the Hydras are liable to great 

 variations both in form and colour the present one has been 

 refered to the H. vulgaris, as it bears the closest resemblance 

 to it. It appears to be the variety b. grisea, Johnston ; but 

 though the tentacula are longer than the body, yet they are of 

 a claret red and not olive green colour. The body is red, 

 gelatinous, and ovoid ; the tentacula vary in number from 

 seven to twelve are long and granular, but vary in length 

 and size according to the degree of their contraction. This 

 is one of the creatures on which Trembly performed his 

 celebrated experiments. His conclusions have been verified 

 by subsequent observers. Their powers of supporting life 

 under the most violent injuries are all but miraculous, and 

 more nearly resemble the attributes of Milton's Angels, 

 than any reality, 



Vital in every part, not as frail as man 

 In entrails, heart, or head, liver or veins, 

 Cannot but by annihilating die ; 

 Nor in their liquid texture mortal wound 

 Receive, no more than can the fluid air. 



