322 DESCRIPTION OF [Polygastrica. 



middle of the body is sometimes filled with delicate white 

 granules (ova). This animalcule generally has a peculiar 

 thrusting forward and back movement, but can climb, run, 

 and swim nimbly, usually with the back undermost. Dr. 

 Ehrenberg found a single animalcule lived nine days : 

 during the first twenty-four hours it formed, by transverse 

 self-division, into three animals ; these in twenty-four hours 

 more formed two, in the same manner ; so that, by self-di- 

 vision only (without ova), they increase three or four-fold 

 in twenty-four hours, and thus a million may be produced 

 from a single animalcule in ten days. An abundant sup- 

 ply of food favours self-division. Found in infusions and 

 amongst oscillatoria. Size 1 -240th to l-96th. 



546. STYLONYCHIA pustulata (Trichoda acarus, M.) 

 The flounder Animalcule has a white body, which is turbid, 

 elliptical in shape, attenuated at both ends, and having a 

 band of uncini at the middle of the belly. Ehrenberg has 

 seen transverse and longitudinal division, and the growth 

 of gemmae. Found in infusions. Size 1-1 44th; ova gra- 

 nules 1 -24000th. 



547. STYLONYCHIA silurus (Trichoda silurus, Kerona 

 silurus, Plymentopu* lava, fyc., M.) Body small, white, in 

 the form of a muscle, cilii and uncini rather long. Found 

 in fresh water. Size l-280th. 



548. STYLONYCHIA appendiculata. The spur Animalcule. 

 Body elliptical, white, small, and flat ; cilii and styles 

 long, the setae disposed obliquely in fascicles. Found in 

 fresh water. Size l-280th. 



549. STYLONYCHIA histrio (Paramecium histrio, Ke- 

 rona histrio, M.) The mask Stylonychia. Body elliptical, 

 white, middle slightly turgid, anterior finished with a 



