PARASITIC FLATWORMS 



401 



120 (123) 



121 (122) 



Intestinal crura short, diverging, not passing acetabulum. . 121 

 Testes symmetrical, lateral, postacetabular. 



Subfamily MICROPHALLINAE Ward 1901. 



Small distomes having pear-shaped body with mobile anterior region 

 containing alimentary system. Suckers small, prepharynx, pharynx 

 and long esophagus present; crura short, not surpassing acetabulum. 

 Excretory system V-shaped. Genital pore sinistral, rarely post- 

 acetabular. No cirrus-sac. Seminal vesicle immediately preacetabu- 

 lar. Testes symmetrical, behind acetabulum. Ovary dextral, along- 

 side of acetabulum. Vitellaria symmetrical, behind testes, in form 

 of a lobed mass of follicles. Uterus coiled in posterior region, ex- 

 tending anteriad about as far as posterior margin of acetabulum. 

 Eggs small, very numerous. 



In intestine of water birds and fishes. 



Representative American genus. 



Microphallus Ward 1901. 



One species (M. opacus) in Amia calva, Micropterus dolomieu, An- 

 guilla chrysypa, Ictalurus punctatus, Percaflavescens; the young dis- 

 tome encysted in crayfish. 



FIG. 695. Microphallus opacus. Ventral view; dotted line represents 

 limits of coils of uterus, filled with eggs. X 37- (After Ward.) 



122 (121) Testes oblique, in center of body, posterior to acetabulum. 



Protenteron Stafford 1904. 



Small distomes. Broadest at center, narrowed behind. Skin spinous. Oral sucker termi- 

 nal, o.i 86 mm., acetabulum 0.62 mm. in diameter. Prepharynx longer than pharynx or 

 esophagus. Crura short, diverging, not passing acetabulum. Black eye spots lateral to 

 pharynx. Testes oblique hi center of body behind acetabulum. Ovary in front of left testis. 

 Uterus reaching posterior end. Vitellaria lateral, short, from fork of intestine to near ovary. 

 Cirrus (and sac ?) extending posteriad to ovary. Eggs 22 by n n. 



Type species Protenteron diaphanum Stafford 1904. 



Intestine of AmbloplUes rupestris; Montreal, Canada. 



123 (120) Intestinal crura extend beyond acetabulum 124 



124 (125) Uterus forms rosette in center of body. 



Centrovarium Stafford 1904. 



Small distomes, tapering somewhat towards both rounded 

 ends. Ventral sucker larger than oral, at end of anterior third of 

 body. Crura terminate opposite center of ovary. Testes behind 

 ends of crura., not conspicuous. Uterus rosette-shaped, hi center 

 of body. Vitellaria lateral, from esophagus to anterior margin of 

 testes. 



Only species known. 



Centrovarium lobotes (MacCallum) 1895. 



Delicate worms, i to 3 mm. long. Suckers relatively small and 

 weak. Ovary deeply lobed. Acini of vitellaria more or less con- 

 fluent imparting a tubular appearance to the organ. Eggs very 

 numerous, small, pyriform, 32.5 by 15 M, with thick brown shell. 



Intestine of Esox lucius, Stizostedion vitreum, AmbloplUes 

 rupestris, Anguilla chrysypa; Ontario, Canada. 



FIG. 696. Centrovarium lobotes. Dorsal view. Magnified. (After 

 MacCallum.) 



