ZOOLOGY 



toed tail, but there are species (as Melicerta) which are 

 attached and surrounded by a tube. These tubes stand 

 on end, projecting at right 

 angles to the surface to which 

 they adhere. Rotifers are 

 most abundant in fresh water, 

 but rather numerous species 

 occur in the sea. Some ab- 

 errant genera are parasitic. 

 A remarkable property of 

 rotifers is that of resisting 

 desiccation ; as the. water in 

 which they live dries, they 

 secrete gelatinous plugs at 

 either end of the body and 

 are thus protected within 

 their own skins, where they 

 can resist great extremes of 

 temperature as well as dry- 

 ness. This property enables 

 them to survive the most un- 

 toward circumstances, and to 

 be carried accidentally from 



place tO place, with the re- From Perrier 's" ^ Train deZoologie" 



Suit that the Species are ex- FIG. 59. A rotifer, Hydatina senta, 



tremely widely distributed. 



female; greatly enlarged. 



References 



HARKING, H. K. Bulletin 81, United States National Museum. Gives a list 



of all the known species, and a full bibliography. 

 Cambridge Natural History, Vol. II. Good general account by Marcus 



Hartog. 



