THE WHEEL ANIMALCULES (ROTATORIA) 6ll 



104 (103) Corona drawn out into long pointed arms, which bear cilia arranged 



in whorls Stephanoceros Ehrenberg. 



One species only (Fig. 937). . Stephanoceros eichhornii Ehrenberg. 



105 (102) No cilia on corona Family APSILIDAE . . 106 



106 (107, 108) Body short, sac-like Apsilus Metschnikoff. 



Corona a large sac or chamber; no foot; attached by an adhesive disk. Two or three species. 



Representative species (Fig. 938). . . . Apsilus bucinedax Forbes. 



107 (106, 108) Body longer, fusiform, a narrowed neck separating off a 



conical anterior part. ....... Atrochus Wierzejski. 



Corona a membranous ring with five short lobes bearing tentacles. 



Only one species (Fig. 939). . Atrochus tentaculatus Wierzejski. 



108 (106, 107) Body long, with a long, slender, tapering stalk. 



Acyclus Leidy. 

 Corona with but one large dorsal lobe. Living in colonies of Megalotrocha alboflavicans. 



Representative species (Fig. 941) Acyclus inquietus Leidy. 



109 (2) Corona surrounded by two parallel wreaths of cilia with a furrow be- 



tween. Cilia of outer wreath always shorter than those of 

 inner. 



Order Melicertida . . no 



The furrow between the wreaths of cilia sometimes clothed with short cilia. Jaws malleo- 

 ramate (Fig. 866). Foot never ending in two toes side by side; sometimes lacking. Eyes two, 

 rarely absent. Fixed or free swimming; the free-swimming species often without foot and 

 frequently bearing appendages on the body. 



no (121) Free swimming and not in tubes or in colonies. ...... in 



in (120) Not spherical 112 



112(115) With a lorica. Without appendages. 



Family PTERODINIDAE . . 113 



113 (114) Foot present, long, ringed, ending in a bunch of cilia. 



Pterodina Ehrenberg. 

 Lorica more or less flattened dorso-ventrally. Many species. 



Representative species (Fig. 942). . . Pterodina patina Ehrenberg. 

 (Fig. 866, B, page 575). . P. casca Parsons. 



114(113) No foot Pompholyx Gosse. 



Lorica not flat. Two or three species 



Representative species (Fig. 940). . . Pompholyx, complanta Gosse. 



