1885.] £S [Stokes. 



of par-oral cilia developed on the left-hand margin, a membrane and a 

 pra3-oral ciliary fringe on the right-hand border ; nucleus multiple, the 

 nodules small, ovate or sub-spherical, scattered throughout the entire body ; 

 contractile vesicle single, spherical, near the center of the left-hand side of 

 the peristome-field; immotile hispid dorsal setae very small and fine ; par- 

 enchyma not vacuolar. Length of body 1-60 inch. Habitat. —Marsh water, 

 with Sphagnum. 



In Urostyla gigas (Fig. 3) we have the largest member of the genus and 

 a giant among Infusoria. Its movements too are correspondingly slow, 

 with much doubling and twisting of the body. And its appetite seems 

 also in proportion to its size, very little that can be forced through the oral 

 aperture coming amiss, even angular grains of sand being occasionally 

 swept into the endoplasm. 



The parenchyma is as conspicuously vacuolar as in Hemicycliostyla 

 sphagni, the trabecular structure being most extensively developed at the 

 extremities. This condition is constant, none of the numerous individuals 

 observed being without it. In appearance it resembles the similar condi- 

 tion of the parenchyma in Loxodes rostrum Ehr. and Trachelitis ovum Ehr., 

 probably being nearer that of the former, inasmuch as the pseudo-cellular 

 structure does not vary in the same individual, at least while under obser- 

 vation, whereas in Trachelius ovum changes in size, position and arrange- 

 ment of the trabecular are frequently made under the eye of the investi- 

 gator, and two individuals are seldom captured with precisely the same 

 plan of vacuolar distribution. But with U. gigas from this vicinity, one 

 arrangement seems quite general and constant. Whether this will obtain 

 in others from a different locality is conjectural. 



The nuclei are wonderfully numerous. I have found it impossible to 

 count them with the same result twice in succession, since they are not only 

 irregularly distributed in different planes, but because the animalcule's 

 writhing and twisting movements make such attempts impracticable. 

 They number, however, from forty to sixty. That they are connected by a 

 funiculus, either in the present forms or in Hemicycliostyla sphagni or 

 H. trichota, I have been unable to ascertain. But if a connecting thread 

 exists, it must be very frail, since the nuclear nodules float out freely and 

 separately from the disintegrated dead body. 



Aside from these peculiarities the Inf usorian can be easily recognized by 

 the arrangement of the double row of curved vibratile seta? on the poste- 

 rior extremity. They add much to the creature's attractiveness, and when 

 quiescent are about the first part of the great Infusorian to catch the eye. 



Urostyla gigas, sp. nov. (Fig. 3). Body elongate, extensile, very soft 

 and flexible, when extended five times as long as broad, widest centrally, 

 tapering toward both extremities, the posterior rounded and slightly 

 curved toward the left-hand side, the anterior narrower, rounded and 

 curved toward the right hand side ; frontal styles five or six ; ventral seta? 

 clothing the entire lower surface in closely approximated lines ; anal styles 

 six, small, slender, fimbriated, not projecting beyond the body ; marginal 



