HYDRAID.E : HYDRA. 125 



Hah. Still waters in England, rare. In a pond at Hackney, Mr, 

 John Ellicot.* " In the pond at Cranmore (near Belfast), Sept. 

 1812," J. Templeton. 



" The tails of these are long, slender, and transparent, and, when 

 placed before the microscope, a long straight gut may plainly be 

 distinguished passing from the body-part or stomach to an opening 

 at the end thereof. These are rather lighter-coloured than the 

 former (H. vulgaris), and have seldom more than six or eight arms, 

 but those capable of great extension." — Baker. 



Baker reckoned that his English exemplars were of a sort dif- 

 ferent from those he had received from M. Trembley, but the only 

 apparent difference lies in the greater shortness of the tentacula of 

 the former; and this is a character liable to considerable variation, 

 and insufficient of itself for specific distinction. The species has 

 been beautifully illustrated in Trembley's "Memoires" by the 

 pencil and graver of the celebrated Lyonnet ; for it is an interesting 

 fact, that all the figures, and most of the plates, which adorn the 

 admirable book just mentioned, were drawn and etched by the 

 author of the " Traite anatomique de la chenille du saule,"t and are, 

 indeed, among the very earliest specimens of his extraordinary at- 

 tainments in these arts. 



In his Plates 86 and 87 Rosel delineates, with his usual elegance, 

 a very remarkable proliferous variety — a great number of young 

 ones pullulating from the very base of the principal polype, and 

 challenging a comparison with some proliferous varieties of the 

 onion cultivated by curious gardeners. 



It may be worth while to call attention to the remarkable resem- 

 blance of the Hydra fusca to the Cucullanus cirratus of Miiller, 

 Zool. Dan. tab. 38, fig. 1-7, which is an intestinal worm ! 



Observations. 



LeeuwenhoekJ discovered the Plydra in 1703, and the uncommon 

 way its young are produced ; and an anonymous correspondent of 



* Elected F.R.S. Oct. 26, 1 738 ; and the author of several papers on subjects in 

 Natural Philosophj'-, published in the Phil. Trans, between the years 1745 and 1750. 

 He was a watchmaker, and died in 177"2. 



t " Ouvrage qui est a la fois le chef-d'oeuvre de Tanatomie at celui de la gravure." 

 Cuvier. — See also Ciiv. Hist, des So. Nat. iii. 256. 



X " Antonius v. Leeuwenhoek, civis Delphensis, peritus vitrorum politer, curiosus, 

 et ad paradoxas opiniones pronus." Haller, Bib. Bot. i. 583. He was born 1632 ; 

 elected F.R.S. January 1630 ; and died in 1723. 



