406 



FRESH-WATER BIOLOGY 



142 (143) Testes oblique, separated by greatly enlarged branch of uterus. 



Dasymetra Nicoll 1911. 



Body moderately flattened, spinous. Pharynx large, crura wide, not 

 reaching posterior end. Excretory vesicle Y-shaped, with many side 

 branches. Genital pore median, slightly preacetabular. Cirrus sac short, 

 plump; cirrus long. No receptaculum seminis; Laurer's canal present. 

 Vitellaria branching, lateral. Uterus coiled in posterior end, ascending 

 ramus wide, nearly straight, metraterm long, muscular. Ova 35 \j. long. 



Type and only species. 



Dasymetra conferta Nicoll 1911. 



Length 3.5 to 4.6 mm., maximum width i to 1.4 mm., near center 

 Spines long, straight. Oral sucker 0.56 mm. in diameter. Acetabulum 

 same size or little less, about 1.7 mm. from anterior end. Pharynx 0.28 

 mm. in diameter; esophagus short; crura wide, enlarged at ends. Ex- 

 cretory tubules pigmented. Testes oblique, separated by uterus. Ovary 

 at right posterior margin of acetabulum. Vitellaria lateral, extend from 

 genital pore to posterior border of right testis; follicles large. Uterus 

 spacious; descending ramus dorsal, small; posterior coil behind ends of 

 intestinal crura; ascending ramus irregular, broad, extending to acetabu- 

 lum. Metraterm with thick muscular walls. Ova dark brown, 33 to 

 37 by 16 to 19 M- 



In mouth (?) of diamond water-snake (Tropidonotus rhombifer}; North 

 America, locality unknown. 



^ FIG. 705. Dasymetra conferta. Ventral view. X 15. (After Nicoll.) 



143 (142) Testes lateral, symmetrical. 144 



144 (145) Topography inverted, i.e., genital pore right and ovary left of 

 median line Pneumatophilus Odhner 1910. 



Broad, flat distomes of submedian size with moderately de- 

 veloped suckers. Greatest width behind center, tapering to 

 anterior end, rounded posteriorly. Skin spinous. Suckers in 

 anterior third of body, acetabulum slightly larger. Genital pore 

 dextral, near fork of intestine, half way between suckers. Oral 

 sucker slightly subterminal, pharynx present, esophagus very 

 short. Crura extend to or just beyond testes, with numerous 

 short lateral projections on outer margin. Excretory vesicle Y- 

 shaped, slender. Stem reaches to anterior margin of testes. 

 Testes opposite, just behind center of body, lobed. Cirrus sac 

 and cirrus moderate in size. Ovary at left posterior margin of 

 acetabulum. Laurer's canal, but no receptaculum seminis. Vi- 

 tellaria extracecal, extend from level of genital pore to anterior 

 part of testes. Uterus with descending and ascending limb pass- 

 ing between testes; thrown into transverse loops that fill post- 

 testicular region. 



In the lung and trachea of Heterodon platyrhinus and Tropi- 

 donotus sipedon. 



One species in North America, originally described by Leidy 

 as Distoma variabile var. b., and listed later by Pratt as Renifer 

 variabilis taken by Odhner as type of the new genus. , - . 



FIG. 706. Pneumatophilus variabilis. Dorsal view. X 12. (After Pratt.) 



145 (144) Topography direct, i.e., genital pore left and ovary right of median 

 line. 146 



