HYDRAID^ : HYDRA. 



121 



suh-C7/Undrical, hut very contractile and mutable in form^ 

 the mouth encircled loith a single series of gramdous filiform 

 tentacula. 



1. H. viRiDis, grass-green; hody cylindrical or insensibly 

 narrowed downwards ; tentacula 6-10, shorter than the body. 



Fig. 2B. 



Polypes verds, Tremhley Mem. 22, pi. 1, fig. 1 ; pi. 3, fig. 1-10.— Fresh-water 

 Polypus, Tremhley in Phil. Trans. Abridg. viii. 623. Folkes in Ibid. 676, pi. 17, 

 and pi. 18, fig. 1-3.— Hydra viridis, Lin. Faun. Suec. 367, No. 1283. Lin. Syst. 

 1320. Mull. Verm. I. ii. 13. Zool. Dan. prod. 230, No. 2783. Encyclop. 

 Method. Vers, pi. 66, fig. 1-8. Berk. Syn. i. 221. lire's Rutherg. 232. Turt. 

 Gmel. iv. 691. Twr^. Br. Faun. 218. Za?». Anim. s. Vert. ii. 60. Steio.Elam. 

 ii. 452, pi. 12, fig. 4, 5. Bees' Cyclop. Vermes, pi. 5, fig. 1. Blnmenhacli''s Man. 

 275, pi. 1, fig. 10. £osc Vers, ii. 274. ^to-A.- Elem. ii. 443. Woodtcard in 

 Mag. Nat. Hist. iii. 349, fig. 89. Roget Bridgew. Treat, i. 162, fig. 59, and 

 176-8, fig. 73-76. Adams on the Microscope, 399, pi. 21, fig. 5. Cams Comp. 

 Anat. tab. 1, fig. 1. Ehrenh. Corall. des roth. Meer. 67. Landshorouyh in Scot. 

 Christ. Herald, n. s. i. 726. Thompson in Ann. and Mag. N. Hist. vii. 481. — 

 H. viridissima, Pall. Elench. 31. — Third sort of Polype, i?aA-er, Polyp. 19, c. fig.— 

 De Groene Polyp met veale annen, Rosel Hist, der Insect, iii. tab. 88, 89. — Le 

 Polype vert, Cuv. Reg. Anim. iii. 295. — L'Hydre verte, Blainv. Actinol. 494, 

 pi. 85, fig. 1. 



Hah. Ponds and still waters, common. 



The polypes of this species differ from the following, " not only 

 in colour, but likewise in their arms, which were much shorter in 

 proportion to their bodies, capable of but little extension, and nar- 

 rower at the root than the extremity, which is contrary to the other 

 species. 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 



