Astasiaea.'] infusorial animalcules. 195 



Peeanema glohulosa. — Body nearly globular, more or less extended 

 anteriorly, with oblique plaits on its surface. In the Seine. Length 

 l-1625thto l-1300th. (P. 21. f. 13.) 



P. virescens. — The animalcule so named, occurred in the water of 

 the Seine, was green, semi-fluid, and changed fonn most rapidly, 

 like an Amoeba. Length 1 -860th. to 1-5 20th. Eeqiiires further 

 examination. 



Genus Zygoselmis. — Animal of variable form, swimming by 

 means of two equal flagelliform filaments, constantly in agitation. 



Zygoselmis is distinguished fi-om Diselmis, by its contractility, 

 and its variability of form. 



Z. nehulosa. — Body colourless, sometimes globular, at others, top 

 or pear-shaped, with numerous contained granules. Length 1-1 300th, 

 with two filaments of equal size and length. (P. 21. f. 12. a. b.) 



Genus Heteeonema. — Body of variable form, oblong, irregularly 

 dilated posteriorly, having a fine flagelliform filament, and a second 

 thicker trailing one, acting as a retractor. 



This genus, by possessing the two filaments, of different characters 

 and office, approaches the Ueteromita (137) and Amsonema (150) ; 

 from which, however, it is distinguished by its contractile, obliquely 

 striated integument. 



H. marina. — Body oblong, irregularly dilated behind, narrower in 

 front, obliquely and closely striated. Length 1 -434th. Foimd in 

 sea water. (P. 21. f. 11.) 



Genus Polxselmis. — Animal oblong, of variable form, swimming 

 by means of several flagellifonn filaments, arising fi-om its anterior 

 extremity. 



The single Infusorium (says Dujardin) bearing these characters, 

 resembled an oblong Euglena, rounded at each end with an anterior 

 longer moveable iilament, suiTounded by three or four very fine 

 shorter ones. 



P. viridis. — Body elongated, rounded at each end, more or less 

 dilated, and folded at the middle ; green, with a red eye-speck. 

 Length 1 -650th. Found in a glass of marsh water, containing 

 Lemna, and which had been kept several months. (P. 21. f. 7.) 



