f56 GENERAL HISTOET OF 



Btnicture. As a tribe, it is evidently more natural than that of 

 the Polygmtrica ; at least there are no such doubtful families as wc 

 find in the latter, namely, the Closterina, BaciUaria, &c. Indeed, 

 the only exception, that can probably be taken, is the genus Btvphano- 

 ceros, which some naturalists class along with the Zoophytes. 



The Rotatoria (sometimes spoken of also as Rotifera) are symme- 

 trical beings, and derive their name from the apparent whirling, 

 wheel (rotayVikB motion of their rotatory apparatus, when set in 

 action; but since, in some instances, the apparatus is so modified 

 that a wheel-like motion is wanting, another appellation has been 

 contrived — viz., SystoUdes, to designate these animals. It is from 

 the very contractile character of their bodies that Dujardin so terms 

 them ; and, indeed, some other name than Rotatoria is requisite, if 

 this naturalist be followed in introducing in the class various 

 animals, furnished with rudimentary hmbs, in pairs, but wanting a 

 rotatory apparatus, and, generally, so modified in structure, as to be 

 fitted for a parasitic existence within the bodies of other animals — 

 such are the members of the family Tardigrada, (DuJ.) 



In such an aiTangement, Mr. Adam White seems disposed to agree 

 with the French naturalist, for he has stated it as his opinion, 

 "that the so-called Acarus folliculorum, and, probably, also Tardi- 

 grada, are parasitic Rotatoria, vnth legs or leg-like appendages 

 adapted to their peculiar habits ; and that their retractile antenna- 

 like, sub-telescopic appendages, may have eyes passing through them 

 as in snails, and may also be the equivalents of the rotce {rotary lobes), 

 but from the limited, or rather the absolutely restricted power of 

 motion of these animals, have neither the ciliary processes, nor the 

 movements and economical uses of the appendages so characteristic 

 of most of the Rotatoria^ (Read before the Linn»an Society, June 

 1851. See Ann. Nat. Hist., vol. vii. p. 424.) 



The Rotatoria are microscopic objects, although many of them are 

 visible to the naked eye as floating specks. They are specially in- 

 habitants of pure water, not occurring in infusions, unless of very 

 recent plants, in which decomposition has not begun. For instance 

 , sagt^-lcavcs, clover, or chopped haj^, are often put to macerate in 

 water, in order to prociu'e specimens of Rotatoria ; the appearance of 



