ySo ORDER HYPOTRICHA. 



This species represents the relatively shortest and widest member of its genus, all 

 other known forms being characterized by their exceedingly attenuate outlines. It 

 was first described by O. F. Miiller under the title of Trichoda ftiusculus, being 

 afterwards referred to the present genus by Ehrenberg. 



Uroleptus gibba, C. & L. sp. 



Body straight, lanceolate, three and a half times as long as broad, 

 rounded anteriorly, somewhat pointed posteriorly ; possessing four rows 

 of ventral setae and a continuous projecting peripheral or marginal series, 

 whose separate elements are rather the longest posteriorly. Length 1-250". 



Hab. — Fresh water. 



Stein has referred to this species, described by Claparede and Lachmann under 

 the title of Oxytricha gibba, as probably belonging to the genus Uroleptus, and finding 

 its nearest ally in U. miisailus. The number of rows of ventral setae distinguish 

 it, however, from this and all other known representatives of the genus. 



Uroleptus piscis, Miill. sp. Pl. XLIII. Fig. 21. 

 Body exceedingly elastic and somewhat variable in shape, broadly linear- 

 fusiform or band-like, from six to eight times as long as broad ; the anterior 

 end rounded, curved slightly to the left ; widest in the centre, tapering 

 gradually towards the posterior extremity, and thence terminating in a 

 strap-shaped, bluntly pointed, tail-like prolongation, which is curved some- 

 what towards the right ; peristome-field extending backwards to about 

 one-fourth of the length of the whole body, its reflected border ciliate ; 

 marginal setae projecting beyond the peripheral border throughout its 

 length, considerably longer around the tail-like posterior prolongation ; 

 median rows of ventral setae two in number, not produced into the 

 tail-like region ; contractile vesicle located close to the left-hand margin, 

 opposite or even anterior to the posterior angle of the peristome ; endo- 

 plasts two in number, posterior to the contractile vesicle. Length of body 

 1-48". Hab. — Fresh water. 



This animalcule is identical with the Trichoda piscis of Miiller, the Uroleptus piscis 

 and Oxytricha caudata of Ehrenberg, and with the Oxytricha caudata of Claparede 

 and Lachmann. 



Uroleptus ratulus, Stein. Pl. XLIII. Fig. zZ- 

 Body persistent in shape, linear-fusiform, about ten times as long as 

 broad; the anterior end rounded, curved slightly to the left, tapering 

 gradually from the centre and terminating in a long, thin, acutely pointed 

 tail ; peristome-field extending backwards to one-fifth of the length of 

 the whole body, very narrow, its reflected border unciliate ; the marginal 

 setae projecting throughout the periphery, very little longer at the posterior 

 or tail-like portion ; the central ventral set^e forming two rows, not pro- 

 duced to the extremity of the caudal appendage ; contractile vesicle 

 developed near the left lateral margin, at a considerable distance from 

 the termination of the peristome ; endoplasts tw^o in number, situated at 

 equal distances one in front of the other behind the contractile vesicle. 

 Length 1-60". Hab.— Fresh water. 



