Philodinaea.] THE INFUSORIA. 397 



longitudinal and foot muscles in three of them ; a furcated 

 foot and horn-like processes in four species; in R. citrinus, 

 the pincer-like portions of the foot appear to be tri-pointed; 

 in R. erythraeus, they were seen to be drawn in. In four 

 species a muscular cesophagal head, with jaws, each two- 

 toothed, is seen ; in three species the alimentary canal is 

 filiform, with a vesicular expansion at the extremity ; it 

 has no cesophagal tube, but is surrounded by a cellular 

 glandulose turbid mass ; one species has a conical, tubu- 

 lar, alimentary canal, without the surrounding mass or ex- 

 pansion at the end ; the four European species have two 

 spherical alimentary glands, and an ovarium, with a few 

 large ova; occasionally these species are viviparous. In 

 three of them a contractile vesicle is present. In R. 

 macrurus, near the alimentary canal, are two sexual 

 glands. In three species from nine to twelve parallel 

 transverse vessels have been observed by Ehrenberg ; and 

 besides these, in the four European species, styliform 

 respiratory tubes, emanating from the neck, which in one 

 species are ciliated anteriorly. The indications of a nervous 

 system are two red frontal eyes, in the four European 

 forms ; and beneath them, in R. vulgaris, are two ganglia. 

 691. ROTIFER vulgaris (Vorticeila Rotator ia, M.) The 

 common wheel Animalcule. This creature, which w T as dis- 

 covered by Leeuwenhoek, has a fusiform white body, gra- 

 dually attenuated towards the foot, the eyes round. "This 

 animalcule was described and illustrated in the Micros- 

 copic Cabinet some years ago, and prior to the appearance 

 of Ehrenberg's observations on them ; it has the power of 

 contracting or extending the length of the body in the fol- 

 lowing remarkable manner : When the creature is about to 



