318 DESCRIPTION OF [Poli/ga.slrica. 



vision is observed in O. lepus and pelionella ; longitudinal 

 only in O. cicada, and perhaps O, puUaster. 



534. OxYTRiCHA rubra {TricJioda piscis et patens, M.) 

 The red Oxytricha. — Body of a brick-red colour, linear in 

 shape, plane on the under side, and equally rounded at the 

 ends. Found in sea water. Size 1-1 40th. 



535. Oxytricha pellionella (Trichoda pellionella, M.) 

 The furred Oxytricha. — Body white, smooth, slightly de- 

 pressed, equally rounded at both ends, often broader in the 

 middle, head not separate, mouth ciliated, and the tail 

 provided with setae. Each animalcule has two oval male 

 glands, and between them a single round sexual vesicle. 

 When self-division commences four glands are developed, 

 and then the vesicle divides. Ehrenberg counted ten 

 cilii anteriorly, and four or five setae posteriorly ; the dis- 

 charge is at the base of the setae. Found in infusions. 

 Size 1 -720th to 1 -280th. 



536. Oxytricha caudata. The tailed Oxytricha is 

 smooth, white, linear, lanceolate in shape, rounded an- 

 teriorly, the posterior attenuated in the form of a tail, 

 which is provided with setse. Found in fresh water and 

 sea water. Size l-576th to l-120th. 



537. Oxytricha platy stoma. The broad-tnouthed Oxy- 

 tricha. — Body white, ovato-oblong, under side flat, pro- 

 vided with setae upon the margin, the mouth large and 

 cihated. It swims with a revolving and vacillating motion, 

 also often upon the back. It creeps upon water plants. 

 Found in standing bog water. Size l-240th. 



538. Oxytricha gibba (Trichoda gibba et fata, M. ) 

 The gibbous Oxytricha. — Body white, lanceolate, ends 

 obtuse, middle enlarged, under side flat and furnished with 



