112 Dr. A. C. Stokes on new Hypotrichous 



latter scarcely projecting beyond the lateral borders, remote 

 from the posterior extremity ; marginal setee uninterrupted, 

 projecting beyond the body posteriorly only ; peristome-field 

 extending through about one fifth the ventral surface, the right- 

 hand border ciliated and bearing an undulating membrane ; 

 contractile vesicle occasionally double, one situated near the 

 centre of the left-hand body-margin, the other smaller and 

 placed near the apical extremity of the peristome-field ; nuclei 

 multiple (usually four), the nodules ovate, each commonly with 

 an externally attached nucleolus ; dorsal hispid setse long, 

 arranged in about six longitudinal series ; endoplasm gran- 

 ular. Length of body -^^ to y^ inch. 



Hah. Pond-water, with algae. Movements rapid and 

 erratic. 



Oxytricha caudata^ sp. nov. (PI. III. fig. 12.) 



Body elongate-ovate, soft and flexible, five or six times as 

 long as broad, the anterior border obliquely rounded and 

 slightly curved toward the left-hand side, posteriorly tapering 

 to the conspicuous, attenuate, pointed, and somewhat retractile 

 tail-like extremity; peristome from one fifth to one sixth as 

 long as the body, the right-hand margin bearing an undulating 

 membrane, the seven or eight adoral cilia bordering the ante- 

 rior extremity large and setose, radiating when quiescent ; 

 frontal styles five, uncinate, with three smaller supplementary 

 setse ; ventral styles five, three anteriorly and two posteriorly 

 placed ; caudal styles five, remote from the posterior extre- 

 mity ; marginal setje uninterrupted, occasionally fimbriated, 

 projecting posteriorly only ; nuclei two, ovate, near the left- 

 hand body-margin ; the single spherical contractile vesicle 

 situated between the nodules, in close proximity with the 

 left-hand body-margin ; hispid setae forming several longitu- 

 dinal dorsal rows, prominently projecting laterally. Length 

 of body Y^xr to jyo inch. 



Hah. Standing pond-water, with Lemna. 



The large, almost uncinate, adoral cilia bordering the frontal 

 region are, when the animalcule is quiescent, to all appear- 

 ance rigidly extended. They then bear a resemblance to the 

 same appendages so abnormally developed in Actinotricha, 

 This Infusorian's movements are rapid, with frequent rather 

 prolonged intervals of rest. So far as I am aware there Is no 

 other species of the genus with the attenuate and somewhat 

 retractile tail-like extremity. The species is readily recog- 

 nizable by these characteristics alone. 



