280 



FRESH-WATER BIOLOGY 



82 (8i) Body elongate, nearly cylindrical, the anterior extremity truncate 



and slightly curved; a short, curved seta borne on either 

 side near the anterior end. - A long, straight bristle extend- 

 ing from the posterior end Loxocephalus Kent. 



Representative species Loxocephalus granulosus Kent 1882. 



Endoplasm granular, mouth on the oblique anterior bor- 

 der although quite indistinct. Nucleus spherical, central. 

 Contractile vacuole posterior. Length 40 to 70 /* Often 

 abundant among decaying vegetable matter. Conjugation 

 readily occurs in infusions. 

 FIG. 494. Loxocephalus granulosus. X 375- (After Edmondson.) 



83 (80) Like Uronema, but with an anterior, spiral row of long cilia. 



Dexiotricha Stokes. 



Representative species. . . .'-> . . Dexiotricha plagia Stokes 1885. 

 Body about three times as long as broad, bearing minute 

 hemispherical protuberances. Cilia setae-like; a row of flexible 

 setae extending from the margin of the mouth obliquely across 

 the right-hand side of the anterior half of the body. Nucleus 

 subcentral; contractile vacuole posterior. Length 60 /*. Pond 

 water. 



FIG. 495. Dexiotricha plagia. X 315. (After Stokes.) 



84(79) Without a posterior bristle '. .,,. v ....... 85 



85 (86) Ellipsoidal to elongate, somewhat acute behind. Mouth lateral, 

 surrounded by a furrow which extends backward. Pharynx 



short with rods. . . Frontonia Ehrenberg. 



Representative species. . .... ... Frontonia leucas Ehrenberg 1838. 



Body elongate-oval, wider anteriorly. Mouth a slit anterior to the 

 middle of the body. Cilia fine, in longitudinal rows. Contractile 

 vacuoles, usually two. Trichocysts numerous. Length 250 to 300 . 

 Stagnant water. 



FIG. 496. 



Frontonia leucas. c, canal; N, macronucleus; , micronucleus; 

 v, vacuole. X 165. (After Calkins.) 



86 (85) Ovate, flattened, rounded at each end. Mouth triangular or crescent- 

 shaped, lateral, in front of the middle of the body. 



Glaucoma Ehrenberg. 

 Representative species. . . . Glaucoma scintillans Ehrenberg 1830. 



The vibratile membranes extending around the mouth pre- 

 senting a bilabial appearance. Nucleus large, central. Con- 

 tractile vacuole posterior. Length 75 /*. Infusions. 



mien-' 



FIG. 497. Glaucoma scintillans. cv, contractile vacuole; macn, macro- 

 nucleus; mien, micronucleus. X 350. (After Biitschli.) 



