676 ORDER PERITRICHA. 



Vorticella dubia, From. PL. XLIX. FIG. 5. 



Body smooth, campanulate, one and a half times as long as broad, the 

 anterior margin scarcely everted, exhibiting no distinct peristomal border ; 

 pedicle thick, not twice the length of the body. Length 1-640". 



HAB. Fresh water. 



The description of this species is very imperfect, but if the figure given by 

 De Fromentel is to be relied on, a permanent feature for diagnosis is supplied by 

 the character of the anterior or oral margin of the animalcule, the peristome alto- 

 gether wanting that raised band-like contour characteristic of almost all other species 

 of the genus. As a consequence of this peculiarity, the anterior border presents 

 an undulating and uneven edge that contrasts strongly with the smooth and sharply 

 denned margin usually associated with this region. 



Vorticella alba, From. PL. XXXIV. FIG. 33, AND PL. XLIX. FIG. 6. 



Body in extension symmetrically ovate or turbinate, one and a half to 

 twice as long as wide, truncate anteriorly ; pyriform when contracted ; 

 peristome-border slightly constricted ; parenchyma very transparent ; cuti- 

 cular surface smooth, finely granulate or punctate ; contractile vesicle con- 

 spicuous; pedicle three or four times the length of the body. Length 

 1-400". HAB. Fresh water, social. 



A species evidently agreeing with De Fromentel's type, as above characterized, 

 has been recently obtained by the author in some abundance and in company 

 with Vorticella hamata, attached to Chara and ConferuacecB obtained from an 

 aquarium of some years' standing, in the Biological Laboratory, South Kensington. 

 The exceedingly neat and symmetrical contour of the body, together with the trans- 

 parency of the parenchyma, serves to distinguish this species readily from the 

 numerous other forms comprehended in this generic group. In one or two 

 examples, as indicated in the zooid to the left-hand side of the group here figured, 

 it was observed that a more or less conspicuously developed annular line or plication 

 divided the narrower posterior third from the two wider anterior thirds of the body, 

 while the cuticular surface under high magnification exhibited in all instances fine 

 longitudinally disposed granulations. 



Vorticella fluviatilis, From. PL. XLIX. FIG. 7. 



Body ovate, smooth, one and a half times as long as broad, truncate 

 anteriorly, having an indentation or depression at the posterior end or point 

 of insertion of the pedicle ; peristome-border narrow, scarcely everted ; 

 cuticular surface smooth ; oral fossa relatively large ; pedicle three or four 

 times longer than the body. Length 1-640". HAB. Fresh water. 



Vorticella crassicaulis, S. K. 

 PL. XXXIV. FIGS. 25 AND 26, AND PL. XLIX. FIG. 8. 



Body when extended ovate or subfusiform, widest centrally, tapering 

 towards each extremity, but more so posteriorly, about twice as long as 

 broad, pyriform, with a snout or nipple-like anterior projection when con- 

 tracted ; peristome-border truncate, constricted and not everted ; pedicle 

 equal to or but slightly exceeding the body in length, very thick at its 



