Hydatiwtea.'} TH E INFUSORIA. 357 



585. PLEUROTROCHA constricta. The robber Pleuro- 

 trocha. Body elongated, conical, and separated from the 

 head by a stricture ; front oblique, toes straight and 

 slender. This animalcule is very active and powerful ; it 

 seems to be predaceous. Found upon Ceratophyllum. 

 Length 1- 144th. 



586. PLEUROTROCHA leptura. The thin-footed Pleurotro- 

 cha. Body turgid in the centre, front oblique, foot slender, 

 toes thin and slightly curved. Found amongst conferva. 

 Length 1-1 44th. 



Genus CLII. FURCULARIA. The forked-fish Rotatoria 

 have a single frontal eye, and a forked foot resembling a 

 tail ; the vibratile organ is compound. Longitudinal mus- 

 cles exist in F. gibba, and foot muscles in three species. 

 The oesophagus is very short, its head has two jaws, each 

 with a single tooth (monogomphia), in two species, but 

 not in the others ; a simple conical alimentary canal 

 (coelogastrica}, with two ear-like glands, exists in all the 

 species, and ovarium is distinct ; but in F. gibba only a 

 contractile vesicle. Vessels, respiratory tubes, gills, &c., 

 are not recognizable ; the organs of sensation are a red 

 visual point on the frontal region, and in F. Reinhardti a 

 sort of brain-like mass is seen. 



587. FURCULARIA gibba. The hump-backed Furcularia. 

 Body oblong, slightly compressed, under side flat, back 

 convex, toes forked, long (styliform), equal to half the 

 body ; the eye is placed upon a nervous ganglion over the 

 mouth, clearly indicating the dorsal surface ; the ovarium 

 has, generally, one large and ripe ovum ; the movement of 

 this animalcule is somewhat slow. Found in green water, 

 and amongst conferva. Length l-96th. 



