148 DESCRIPTION OF {Tolygastrica. 



substance is situated, producing the colour of the body. It is fur- 

 nished with a delicate flagellifomi proboscis. The red circle, so re- 

 markable a featui-e in this species, always appears to abide in the 

 same horizontal pobition, how quickly soever the creatiu-e may be 

 revolving on its longitudinal axis. Figm^e 30 represents this crea- 

 ture with its proboscis extended; figure 31, another with it retracted ; 

 figiu-e 32 is a very young specimen ; and 33, a full grown one, that 

 has been pressed between two plates of grass, so as to exhibit the 

 lorica broken without destroying any part, except the red circle 

 above noticed. Found amongst confervse. Size l-860th. 



Teachxlomon^as cylindrica. Form oblong, approaching to cylin- 

 drical; proboscis almost as long as the body. Colour a beautiful 

 green; eye red ; ring purple. Size 1 -1000th. 



T. arceolata. Form of lorica globose, surface areolated. 

 T. aspera. Figure of lorica similar to preceding, but its surface 

 covered with rough points. 



T. granulata. Similar, but its surface very minutely granulated. 

 T. loivis. Lorica also globose, with its surface smooth. 

 T. pyrwn. Lorica oblong or pear shaped (pyriform) smooth. 

 Dujardin, in his family Thecamonadina, includes some genera of 

 animalcules not described by Elu'enberg, or otherwise, described 

 under different names and a diverse arrangement. They are appended 

 here as best agreeing with the Oryptomonadina. 



Genus Phacus. (D.) Body flattened and leaf-like, mostly green, 

 and displaying a red speck in front, together with a flagelliform 

 filament, and a resistant membranous integument prolonged pos- 

 teriorly in the form of a tail. 



This genus comprehends some animalcules, referred by Ehrenberg 

 to his genus Euglena, on account of similarity in colour. The differ- 

 ence between the two genera is, however, considerable, for in Euglena 

 the integument is contractile, and peiTuits of a frequent change ot 

 form, whilst in Phacus, on the contrary, the integument appears 

 quite wanting in contractility, and the animal invariable in form. 



The enclosing integument of Phacus persists after the death of the 

 animal ; after the destruction of the contained green mass, and also 

 after the action of various chemical agents, becoming, in the latter 



