280 ORDER FLAGELLATA-PANTOSTOMATA. 



The colonies of this species closely resemble a number of zooids of Bicosceca 

 lacustris grouped together at the extremity of a common rigid pedicle. This 

 supporting stem is itself of variable dimensions, being sometimes only half as long 

 as, but more often considerably exceeding in length the ovate loricae. The com- 

 pound groups of this species are apparently produced by the repeated longitudinal 

 fission of a primary naked zooid of abnormal size, the formation and induration of 

 the loricae being accomplished subsequently. Examples of this type have been 

 obtained from both Wandsworth Common and a pond near Acton. It was 

 originally referred by the author to the genus Dinobryon, and is figured in connection 

 with that generic title in the ' Popular Science Review' for April 1878. 



Fam. VII. AMPHIMONADID^:, S. K. 



Animalcules naked, free-swimming, or sedentary and adherent by a 

 prolongation of the posterior extremity or by a distinctly developed 

 caudal filament ; flagella two in number, terminal, of equal size ; no distinct 

 oral aperture, food-substances being incepted at all points of the periphery. 



The even development of the two flagella serves to distinguish the representatives 

 of this family group from those of the Dendromonadidae. 



GENUS I. GONIOMONAS, Stein. 



Animalcules free-swimming, persistent in shape, the anterior border 

 obliquely truncate, having at the apex of the projecting angle two subequal 

 and closely approximated flagella ; multiplying by longitudinal fission. 



HAB. Fresh water. 



This generic group is instituted by Stein * for the reception only of the Monas 

 truncata of Fresenius. 



Goniomonas truncata, Fres. sp. PL. XIV. FIGS. 31-33. 



Body ovate, compressed, from one and a half to three times as long as 

 broad, rounded posteriorly, the anterior border abruptly and obliquely 

 truncate, with a sharply pointed and projecting anterior angle ; flagella 

 short, of uniform size, scarcely equalling the body in length, inserted at the 

 apex of the projecting angle ; parenchyma transparent, granular, enclosing 

 near the anterior border a transversely placed, dark, band-like body ; con- 

 tractile vesicle situated on the shorter lateral border, a little behind the 

 band-like body ; endoplast located near the centre of the opposite or longer 

 lateral border. Length 1-2500" to i-iooo". HAB. Fresh water. 



This species, synonymous with the Monas truncata of Fresenius, f has been 

 recently encountered by both Biitschli and Stein, the former regarding it as. a 

 migrant member of the genus Spumella, to which he has provisionally relegated it, 

 while the latter, as already mentioned, has instituted the present generic title for 

 its reception. By both of these authorities has the anterior band-like body, first 

 delineated by Fresenius, been observed, but is in either case evidently diversely 



* ' Infusionsthiere,' Abth. iii., 1878. 



t " Beitrage zur Kenntniss Mikroskopischer Organismen," 'Abhandl. d. Senckenbergischen 

 Naturforschenden Gesellschaft,' Frankfort, 1858. 



