Trachelina.] THE INFUSORIA. 297 



The intestinal Bursaria has a slender cylindrical body, at- 

 tenuated posteriorly ; mouth small, below the frontal apex. 

 In this species, as well as in others, Ehrenberg has seen 

 transverse self-division. Size 1 -240th to l-120th. 



481. BURSARIA (?) cordiformis. The heart-shaped Bur- 

 saria. Body reniform, front depressed, mouth slightly 

 curved in a spiral manner; colour white. Size 1-2 10th. 



482. BURSARIA lateritia (Trichoda ignita, M.) The 

 brick-red coloured Bursaria. Body compressed, ovato- 

 triangular, with the front sharply crestated. Found with 

 lemna, conferva, &c. Size 1-43 Oth to 1-1 44th. 



(6.) FRONTONIA. Anterior part of the body (brow) projects 

 beyond the mouth, and is convex. 



483. BURSARIA vernalis (Leucophra virescens, M.) The 

 spring Bursaria has an oval turgid body, rounded at the 

 ends, and attenuated posteriorly. The mouth has a wreath 

 of stiff short bristles, resembling teeth ; numerous stomach 

 vesicles are often filled with large Oscillatoriae, Naviculae, 

 &c., and contain a reddish bile. The process of digesting 

 the Oscillatoriae is interesting to follow : they are at first 

 elastic and rigid, and of a beautiful blue green colour, then 

 distinctly lax, flexible, and bright green, becoming after- 

 wards yellowish-green, and falling into separate articu- 

 lations, which at length turn yellow. Found amongst 

 oscillatoria in spring. Length l-144th to l-120th, 



484. BURSARIA leucas. The white Bursaria. Body 

 oblong, cylindrical extremities nearly equi-convex, bile 

 colourless (see fig. 295). This creature has a contractile 

 bladder, with a curious jagged margin near the long open 

 mouth. Found with oscillatoria, and on the surface of 

 water. Size 1-1 44th, 



