PARASITIC FLATWORMS 



387 



57 (58) Vitellaria consist of few large follicles or form paired compact organ. 

 No cirrus sac. . . Subfamily DIPLODISCINAE Cohn 1904. 

 Moderate sized amphistomes with conical body, round in transsection, attenuated ante- 

 riorly. Terminal sucker very large. Intestinal crura extend to terminal sucker, relatively 

 broad. Vitellaria a few large follicles on each side which may be 

 condensed into a more or less compact but lobed organ. 

 In alimentary canal of Amphibia and Reptilia. 



Only North American genus. 



Diplodiscus Diesing 1836. 



Two testes confluent in older specimens. Genital pore near oral 

 opening. Esophagus long, pharynx-like enlargement at bifurcation 

 of intestine, not sharply marked off. Excretory vessels looped into 

 coils, some above and some below intestine. 



Only North American species. 



Diplodiscus temper atus Stafford 1905. 



Rectum of various frogs, 

 braska, Minnesota. 



Canada, Pennsylvania, Indiana, Ne- 



FIG. 672. Diplodiscus temper atus. Adult worm somewhat contracted, 

 drawn from the ventral side as a transparent object. Magnified. (After 

 Gary.) 



58 (57) Vitellaria consist of small scattered lateral follicles. Cirrus sac 



present. . . . Subfamily SCHIZAMPHISTOMINAE Looss 1912. 

 Representative North American genus. 



Allassostoma Stunkard 1916 . . 59 



Large oral invaginations open independently into oral sucker; no preoral sphincter; esoph- 

 ageal bulb composed of concentric muscle lamellae. Hermaphroditic duct present. Germ 

 glands median, near center of body. Both testes anterior to ovary. Vitellaria consist of small 

 scattered lateral follicles, in posterior region with median follicles also. Laurer's canal opens in 

 mid-dorsal line anterior to excretory pore. 



59 (60) Large worm (over 10 mm. long) with small suckers. 



Allassostoma magnum Stunkard 1916. 



Length 10 to 12 mm., breadth 3 to 5 mm., thickness 1.5 to 2 mm. 

 Living worm clear, slow-moving, capable of great extension. Acetabu- 

 lum sub-terminal, ovoid, wider anteriad, 2 to 2.5 mm. long by 2 mm. wide. 

 Oral sucker terminal, 0.9 to 1.35 mm. long by 0.6 to 0.9 mm. wide; oral 

 pockets arise at posterior end of oral sucker by separate lateral openings 

 and extend dorsad and caudad. 



Testes oval, 0.27 to 0.35 by 0.45 to 0.9 mm., long axis transverse, 

 located near center of body and slightly oblique. Ovary median, spheri- 

 cal or oval, 0.28 to 0.35 by 0.33 to 0.57 mm. in diameter. Vitelline 

 follicles small, sparse, anteriorly extracecal, but posteriorly also intracecal. 

 No receptaculum seminis and no viteUine reservoir. Eggs o.i by 0.13 

 mm. 



In intestine of Pseudemys; Illinois, Missouri. 



FIG. 673. Allassostoma magnum. Ventral view. X 2. (After Stunkard.) 



60 (59) Small worm (length about 3 mm. or less) with large suckers. 



Allassostoma parvum Stunkard 1916. 

 From Chelydra serpentina; Urbana, III. 



