160 PROTOZOA. 



with two flagelliform filaments, one arising from the 

 front, the other from the end of the body. In Cer- 

 comonas crassicau'da (fig. 18) the posterior filament 

 is replaced by a tail-like narrowing of the body. 



Heteromita ovdta (fig. 19) has the body ovate, 

 with two long anterior flagelliform filaments, one of 

 which is directed forwards, while the other trails 

 behind. 



Anthophysa mul'leri (fig. 20) has the monad bodies 

 arranged in little heads at the ends of an irregularly 

 branched brown stalk. After a time they become 

 detached and revolve freely in the water. 



DINOBRY'INA. Dinobry'on sertuldria (PL XI. fig. 

 21) forms a minute Sertularia-like polypi dom, con- 

 sisting of rows of cells, each containing an oval 

 monad with a single anterior filament. The two last 

 species are common in bog-water. 



THECAMONAD'INA. In these Infusoria the body is 

 inclosed in a firm and sometimes brittle shell or cara- 

 pace. 



Trachelomonas volvoc'ina (PL XI. fig. 22) has a 

 spherical red shell, the body being furnished with a 

 single filament and a minute red eye-spot ; while 

 Chatoglena volvoc'ina (fig. 23) has an oblong shell, 

 covered with little spines. 



EUGLENIA. In this family the form of the body 

 is constantly changing, being at one time spherical, 

 at another fusiform or ovate. It is covered with a 

 contractile skin or firmer external portion, and has 

 one or more flagelliform filaments for locomotion. 

 The species are common in stagnant pools, often 

 colouring the water green or red. 



Euglena viridis (PL XI. fig. 24) has a spindle- 

 shaped body when fully expanded, the ends being 

 pale ; and at the front end is a red eye-spot. 



Astdsia haematodes (fig. 25), which is probably a 

 form of the Euglena, is found in stagnant pools, which 

 it renders red. It has no eye-spot. 



