Infusoria from American Fresh Waters. 107 



figure, but it not rarely is more or less undulate. This Infu- 

 sorian, like all the members of the genus thus far observed, is 

 essentially a bottom-feeder, gliding over the submerged objects, 

 the residual d(^bris at the lowest parts of the shallow w^aters 

 which it inhabits. 



OnychodromopSIS {Onychodromus ; OT/rt?, form), gen. no v. 

 Animalcules free-swimming, soft and flexible, hypotrichous ; 

 frontal styles six, the anterior three largest and most conspi- 

 cuous ; marginal setee uninterrupted; ventral styles in four 

 longitudinal rows, the third sei'ies from the right-hand body- 

 margin, or the second from the left-hand border, interrupted 

 centrally ; anal styles five. 



This differs from Stein's Onychodromus chiefly on account 

 of the softj flexible, and uncuirassed condition of the body. 

 In the present form there is no trace of a dorsal shield or 

 carapace, the body being quite soft and flexible, and further- 

 more bearing on the dorsal cuticular surface numerous short 

 hispid seta^. Stein remarks of the form discovered by him 

 and relegated to the genus Onychodromus^ that the carapace 

 is more indurated than that of Stylonychia, and less so than 

 that of Euplotes, which is by no means the condition in the 

 present form. The frontal styles, which, however, are of but 

 secondary importance in generic diagnosis, are from sixteen 

 to twenty-eight in number in Onychodromus^ and the very 

 important ventral setge from fifteen to twenty-one ; in Ony- 

 chodromojpsis the former are six in number, and the latter very 

 numerous and arranged in a characteristic manner. 



Onychodromopsis flexilisj sp. nov, (PL III. fig. 4.) 

 Body ovate or subelliptical, about three times as long as 

 broad, somewhat narrowed anteriorly and slightly curved 

 towards the left-hand side ; marginal setse longest and largest 

 at the posterior extremity ; ventral styles in four longitudinal 

 rows, the second, counting from the left-hand body-margin, 

 centrally interrupted, consisting of two or three anterior and 

 two or three posterior elements ; anal styles five, nearly mar- 

 ginal, often furcate or fimbriate, projecting beyond the poste- 

 rior border; peristome about one third as long as the body 

 the inner or right-liand margin bearing a large and, in 

 lateral view, conspicuous membrane ; nucleus double, near the 

 left-hand body-margin, but indifferently in the anterior or 

 posterior body-half; contractile vesicle near the centre of the 

 left-hand margin ; dorsal hispid setee short, inconspicuous, and 

 abundant. Length of body ^ko to ^kr inch. 

 Hah. Standing pond-water, with Lemnce. 



