GENUS HOLOPHRYA. 499 



Holophrya discolor, Ehr. 



Body ovate, pointed posteriorly, about twice as long as broad ; cilia 

 long, disposed in widely separated longitudinal rows ; parenchyma green or 

 colourless. Length 1-240". Hab. — Pond water. 



Holophrya tarda, Quenn. Pl. XXVI. Figs. 59 and 60, 



Body when extended nearly three times as long as broad, elongate- 

 pyriform, somewhat flask-shaped, rounded posteriorly, tapering gradually 

 towards the narrower and truncate anterior extremity; cuticular surface 

 finely ciliate, striate longitudinally ; body in contraction subspherical, 

 with the longitudinal striations obliquely set ; contractile vesicle postero- 

 terminal ; endoplast elongate-ovate, stationed a little in front of the con- 

 tractile vesicle. Length 1-300". Hab. — Salt water. 



This as yet single known salt-water species of the genus Holophrya is figured 

 and described by August Quennerstedt in his " Bidrag til Sveriges Infusoriefauna," 

 contributed to the 'Acta Universitatis Lundensis' for the year 1865. So far 

 as its external contour and the relative form and position of the endoplast and 

 contractile vesicle are concerned, it would appear to be most nearly related to the 

 Holophrya Kessleri of Mereschkowsky next described. 



Holophrya Kessleri, Mereschk. 



Body contractile and variable in form, elongate-ovate, subcylindrical, 

 sometimes slightly wider anteriorly, about twice as long as broad ; cuticular 

 surface alternately grooved and ribbed longitudinally, finely ciliate through- 

 out ; parenchyma transparent or with a yellowish tinge ; contractile vesicle 

 large, posteriorly situated ; endoplast band-like, subcentral. Length 1-170" 

 to 1-130". 



Hab. — Fresh water : Lake Onega (Mereschkowsky), among aquatic 

 vegetation. 



This species is distinguished, according to Mereschkowsky,* by the ribbed char- 

 acter of the cuticular surface and the band-like contour of the endoplast, both of 

 which characters are nevertheless shared by the salt-water Holophrya tarda of A. 

 Quennerstedt. When viewed end-on, these longitudinal ribs are found to range from 

 twenty-five to thirty in number, the animalcule under such circumstances presenting 

 an ahiiost melon-like appearance. It does not appear that these ribs become 

 obliquely twisted when the animalcule is contracted, as obtains in H tarda, 



Holophrya brunnea, Duj. 



Body elongate-cylindrical, equally rounded at the two extremities, two 

 and a half times as long as broad ; colour brown. Length of body 1-125". 

 Hab. — Pond water. 



This form, in common with Holophrya ovum and H. discolor, assumes after 

 feeding a subglobose or perfectly spherical contour. 



* "Studien iiber Protozoen des nordlichen Russland," ' Zeitschrift fiir Wissenschaftliche 

 Zoologie,' Bd. xvi., 1878. 



