No. 2.] FRESH-WATER PROTOZOA. 4I 



13. Much flattened ; with broad, clear border, which may 



be wanting on the right side ; with trichocysts . . 



Loxophyllwn* 

 Somewhat flattened, but with no hyaline border, and 

 commonly no trichocysts Amphileptus* 



14. Mouth anterior to middle 15 



Mouth in middle, or posterior 17 



15. Pharynx basket-like ; body cylindrical to ovate. .Nassula* 

 Pharynx not basket-like 16 



16. Mouth crescentic ; a watch-glass-shaped pigment spot 



near by; a ciliated lobe in pharynx Ophryoglena* 



Mouth surrounded by a furrow extending far back- 

 wards Fontonia* 



Mouth bearing a few long cilia on^its posterior left 

 side; body slightly compressed and ovate. . . .Colpoda* 



17. Mouth near middle; short pharynx; peristome ob- 



lique ; cilia uniform Paramecium* 



Mouth in middle or posterior half of right side; 

 pharynx evident ; long cilia behind the mouth .... 



Conchopthirus 



18. Peristome not evident; mouth near the front 19 



Peristome evident 22 



19. Mouth in front of middle 20 



Mouth near the middle 21 



20. One undulating membrane ; body ovate with anterior 



end slightly curved to the right ; mouth lateral . . . 



Colpidium* 

 Two undulating membranes, body ovate. . . . .'Glaucoma* 

 Two undulating membranes, body elongated. . .Dallasia* 



21. With two membranes; body ovate, slightly com- 



pressed, broader behind, and with a long posterior 



bristle Uronema* 



Like Uronema, but with an anterior spiral row of 

 long cilia Dexiotricha* 



22. Peristome posterior to middle 23 



Peristome not posterior to middle 24 



23. With an evident membrane ; a tuft of long bristles at 



the posterior end Cinetochilum* 



Membrane less evident, and without the long bristles 



Microthorax* 



