Stokes.] *fo [June 19, 



the length of the body, the right-hand border nearly straight, finely ciliate 

 and bearing an undulating membrane ; contractile vesicle double, near 

 the center of the left-hand body-margin ; nucleus double, ovate ; anal 

 aperture sub-terminal, presumably dorsal ; immotile hispid dorsal setae 

 short. Length of body, 1-125 to 1-150 inch. Habitat. — Shallow pools in 

 early spring. 



The form which I have named Holosticha similis (Fig. 7), is readily dif- 

 ferentiated from all other species by the moniliform nucleus. Usually the 

 nodules are arranged in a single row, but individuals occur not uncom- 

 monly with a double row, all the component nodules of each series tben 

 being in contact laterally. Here also the anal aperture is dorsal. 



Holosticha similis, sp. nov. (Fig. 7). Body elongate-ovate, soft, flexible 

 and somewhat extensile, more than four times as long as broad, the poste- 

 rior extremity rounded, the anterior narrower, rounded, slightly curved 

 toward the left-hand side ; peristome-field oblique, confined to the anterior 

 third of the lower surface, narrow, ovate, the right hand margin ciliate; 

 frontal styles about fourteen ; ventral setae in two straight median rows ; 

 anal styles twelve to fourteen, slender, in a long oblique row, only the 

 most posterior ones projecting beyond the body ; marginal setae conspicu- 

 ous, longest, most abundantly developed and projecting at the posterior 

 border ; contractile vesicle single, spherical, on the left-hand side of the 

 apical termination of the peristome-field ; nucleus moniliform, the nodules 

 ovate or subspherical, in a single or double row, placed near the left-hand 

 body-margin ; anal aperture dorsal, near the posterior extremity ; dorsal 

 inmotile hispid setae small and fine. Length of body, 1-130 inch. Hab- 

 itat. — Marsh water, with Sphaghum. 



The following animalcule is rather slow in its movements, especially 

 when in contact with debris or algal filaments, then resting for a time, 

 commonly with the dorsal surface upward, a position giving the observer 

 an opportunity to study the numerous hispid setae projecting from that 

 part, but effectually concealing the more important arrangement of ventral 

 styles and setae. When it has reversed its position, the ventral setae are 

 seen to conspicuously differ in size in the two median rows, as well as in 

 numbers. This difference is not uncommon in members of its genus 

 (Uroleptus), but here it is unusually well marked. A similar difference 

 also exists between the right and left-hand marginal setae, the former being 

 abundant and remarkably flat. This is unusual. 



In many Infusoria the body is prolonged anteriorly as a narrow cres- 

 cent, usually styled the upper lip. In many of these I believe this to be a 

 continuation of the ventral plane and consequently to be in reality a 

 lower lip. Such is the case with Uroleptus dispar, as shown in diagram- 

 matic outline in figure 9. 



Uroleptus dispar, sp. nov. (Figs 8 and 9). Body elongate-oblanceolate, 

 elastic, four to five times as long as broad, widest centrally, tapering pos- 

 teriorly and terminating in a narrow, flattened, tail-like prolongation ; 

 anterior region depressed ; frontal border rounded, the ventral surface 



