Microscopical Essays* .427 



Of the Hydra Pallens. 



The hydra pallens has been defcribed only by M. Roefel, 

 In fee. 3, Polyp. 465, Plate 76, 77 ; it is very feldom to be met 

 with, is of a pale yellow colour, and grows fmaller gradually 

 from the bottom, the tail is fomewhat round or knobbed, the 

 arms are about the length of the body, of a white colour, and 

 generally feven in number, apparently compofed of a chain of 

 globules ; it brings forth the young from all parts of it's body. 

 Linnaeus defines it as hydra pallens tentaculis fubfenis mediocribus, 

 Pallas as hydra attenuata corpore flavefcente, furfum attenuato. 



Of the Hydra Hydatula. 



The next in order is the hydra hydatula, which we have 

 already defined from Linnaeus as a hydra with four obfolete arms, 

 and a veficular body : it is fpoken of by many medical writers, 

 who are enumerated in the Syftema Naturae, p. 1321. It is 

 defcribed alfo by Hartman, mifc. nat. cur. dec. t an. 7, obf. 206, 

 dec. II. an. 4, obf. 73, as hydatis animata ; alfo in the diflert. 

 de inf. viv. p. 50, n. 6, taenia hydatoidea. Pallas defines it as 

 taenia hydatigena rugis imbricata corpore poflice bulla lymphaticas 

 terminate The defcription I fliall give the reader will be ex- 

 tracted from the Philofophical Tranfactions, No. 193, by Dr. 

 Tyfon, who names it lumbricus hydropicus. 



In the diffeclion of a gazella, or antelope, Dr. Tyfon obferved 

 feveral hydatides, or films, filled with water, about the bignefs of 

 a pigeon's egg, and of an oval form, fattened to the omentum, and 

 fome in the pelvis, between the bladder of urine and the re&um ; 



