Stokes.] J& [June 19, 



setae longest and most abundantly developed about the posterior extremity, 

 the right-hand border of which bears two oblique rows of long arcuate 

 vibratile setae, one series originating on the dorsal surface ; peristome-field 

 confined to the anterior one-fourth of the ventral surface, the right-hand 

 border ciliate, and an endoral series depending centrally ; contractile vesi- 

 cle single, spherical, on the left-hand side of the peristome-field ; nucleus 

 multiple ; anal aperture opening on the dorsal surface at some distance 

 from the posterior extremity ; parenchyma vacuolar ; hispid immotile dor- 

 sal setae short. Length of extended body 1-30 inch. Habitat. — Marsh 

 water, with Sphagnum. 



Another species of this same genus (Fig 4), resembling the preceding, 

 yet sufficiently dissimilar to warrant the formation of a new specific title 

 for its reception, is not uncommon in the Sphagnum. It, too, is compara- 

 tively gigantic, but the general aspect, aside from minute structural char- 

 acteristics, renders it readily recognizable. The posterior portion is pro- 

 longed as a broad tail-like continuation, a feature thus far restricted to 

 this member alone of the Urostylae. The right-hand postero-lateral border of 

 this part supports a single series of long arcuate setae similar to the double 

 row on V. gigas, the contractile vesicles are ten to twelve in number, and 

 the peristomal structure is distinctive. To accurately ascertain the number 

 of the pulsating vacuoles is almost as difficult as to count the number of 

 nuclear nodules, but there are not less than ten nor more than twelve, 

 their presence at once separating the Infusorian from all the species and 

 making necessary a slight change in the generic diagnosis as it now stands. 

 This form I have named Urostyla caudata. 



Urostyla caudata, sp. nov. (Fig. 4). Body elongate-elliptical, soft, flex- 

 ible and extensile, five times as long as broad, widest centrally, the ante- 

 rior extremity rounded and curved toward the left-hand side, the posterior 

 portion narrowed into a straight, broad tail-like prolongation ; frontal 

 styles about twenty ; ventral setae clothing the entire ventral surface in 

 closely approximated longitudinal lines ; anal styles eight to ten, long, 

 slender, in an oblique row, usually projecting beyond the body ; marginal 

 setae projecting posteriorly and developed on the right-hand border of the 

 posterior extremity as a single obliqie series of long arcuate setae ; peris- 

 tome-field confined to the anterior third of the lower surface, the left hand 

 margin finely ciliate in addition to the adoral fringe, the right-hand border 

 bearing a membrane and a prae-oral ciliary series ; nucleus multiple, the 

 nodules numerous, scattered ; contractile vesicles multiple, arranged in a 

 row along the left-hand body-margin ; parenchyma vacuolar ; anal aper- 

 ture opening on the dorsal surface near the posterior extremity. Length 

 of body 1-40 inch. Habitat. — Marsh water, with sphagnum. 



Previously to the capture of the three forms ot Holosticha here referred 

 to, but a single fresh-water species had been recorded. The structure of 

 these additional sweet-water members of the genus will necessitate a change 

 in the generic description, since the peristomal membrane, the increased 

 number of frontal styles in Z7. hymmophora and U. similis, and the double 



