Family GASTROPODIDAE 



With entire lorica; foot ringed, very retractile, project' 



ing vcntrally 



Common genus — Gastropus 

 Family MICROCODONIDAE 



Mouth in center of the corona (and so often placed 



under Order Collothecacea) \ no lorica; with one toe or 



two unequal toes 



Common genera — Microcodon 

 Mi7^rocodides 

 Family BRACHIONIDAE 



A large and varied group which has been variously 



divided into other families by different writers; with or 



without a lorica of one or two pieces; with or without 



a foot; corona with or without bristles or projections; 



mastax malleate (all parts well developed, for grinding 



and for prehension) 



Common genera — Epiphanes Tslotholca 



Cyrtonia Euchlanis 



Brachionns Lecane 



Schizocerca Monostyla 



Platyms Lapadella 



Squatinella Colurelhx 



Keratella 



KEY TO THE PRINCIPAL GENERA OF ROTIFERS AND 

 GASTROTRICHA 



1. Body usually flattened; v^ithout internal jaws; with two tufts of bristles 



on each side of the head, or head with long spines — 



GASTROTRICHA ^ 2. 



Body usually, but not always, saclike or tubular, sometimes colonial; 

 animal transparent, with internal jaws (mastax) ; usually, but not al' 

 ways, with one or more rings of cilia in the area of the mouth 



ROTIFER A 5. 



2. Rear end rounded 



Dasydytes Gosse 

 Rear end forked 3. 



3. Skin smooth 



Ichthydium Ehrenberg 

 Skin with scales or spines 4. 



4. Skin with diamond-shaped scales; caudal projections jointed 



Lepiduderma Zelinka 



65 



