30 THE EOTIFEEA. 



, well-marked battalions. Nature knows no hard lines of separation; and the best of 

 classifications can be only that which contains the fewest faults : as Miiller has forcibly 

 said, ' Optima est, quae paucioribus horret.' 



Order I. EHIZOTA. 



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

 in a slicking disk or cup. 



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



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

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



Fam. 2. Melicertadce (PI. C, fig. 2). 



Corona not produced into setigerous lobes ; buccal orifice lateral ; ciliary ivreath 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. Philodinadee (PI. C, fig. 3). 



Corona two transverse circular lobes ; ciliary ivreath 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 rarnate. 1 



Fam. 4. Adinetada (PI. C, fig. 4). 



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

 the corona ; trophi ramate. 1 



Order III. PLO!MA. 



That swim ivith their ciliary ivreath, and (in some cases) creep with 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 larger 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/ooi, absent. 



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



