30 THE ROTIFEKA. 



well-marked battalions. Nature knows no bard lines of separation ; and tbe best of 

 classifications can be only tbat which contains the fewest faults : as Muller has forcibly 

 said, ' Optima est, quae paucioribus horret.' 



Order I. Rhizota. 



Fixed when adult ; foot transversely wrinkled, not retractile within the body, ending 

 in a sucking disk or cup. 



Fam. 1. Flosculariada (PI. C, fig. 1). 

 Corona produced longitudinally into setigerons lobes ; buccal orifice central ; ciliary 

 wreath a single half-circle above the buccal orifice ; trophi uncinate. 1 



Fam. 2. MeUcertadm (PL C, fig. 2). 

 Corona not produced into setigerous lobes ; buccal orifice lateral ; ciliary wreath a 

 marginal continuous curve, bent on itself at the dorsal surface, so as to encircle the 

 corona twice, with the buccal orifice between its upper and lower curves, and having also 

 a dorsal gap between its points of flexure ; trophi malleo-ramate. 1 



Order II. Bdelloida. 



That swim with their ciliary wreath, and creep like a leech; foot wholly retractile 

 within the body, telescopic, furcate. 



Fam. 3. Philodinada (PL C, fig. 3). 

 Corona two transverse circular lobes ; ciliary wreath a marginal continuous curve 

 bent on itself at the dorsal surface, so as to encircle the corona twice, with the buccal 

 orifice between its upper and lower curves, and having also two gaps, the one dorsal 

 between its points of flexure, and the other a ventral gap in the upper curve opposite to 

 the buccal orifice : trophi ramate. 1 



Fam. 4. Adinetadce (PL C, fig. 4). 

 Corona a flat ventrally placed surface ; ciliary wreath the furred ventral surface of 

 tbe corona ; trophi ramate. 1 



Order III. Ploima. 

 That swim with their ciliary wreath, and [in some cases) creep toilh their toes. 



Sub-order. Il-loricata. 



Foot, when present, almost invariably furcate ; but not transversely wrinkled ; rarely 

 more than feebly telescopic, and partially retractile. 



Fam. 5. Microcodidce. 

 Corona obliquely transverse, flat, circular ; buccal orifice central ; ciliary wreath a 

 marginal continuous curve encircling the corona, and two curves of larg er cilia, one on 

 each side of the buccal orifice ; trophi forcipate ' ; foot stylate. 



Fam. 6. Asplanchnadce (PL C. fig. 7). 

 Corona two transverse, flattened, confluent cones, with their summits distinct ; 

 ciliary wreath single, marginal; trophi incudate ' ; intestine, cloaca, and foot, absent. 



1 For description of these technical terms, see pp. 28, 29. 



