40I 



121 



PARASITIC FLATWORMS 



1 20 (123) Intestinal crura short, diverging, not passing acetabulum. 



121 (122) Testes symmetrical, lateral, postacetabular. 



Subfamily Microphallinae Ward 1901. 



Small distomcs having pear-shaped body with mobile anterior rcRion 

 contammg ahmentary system. Suckers small, prepharynx. pharynx 

 and long esophagus present; crura short, not surpassing acetabulum 

 Excretory system V-shaped. (Jenital pore sinistral, rarely pcjst- 

 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 lobcd 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. 



MicrophaUus Ward igoi. 

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

 gialla chrysypa, Ictalurus pundatus, Percaflavescens; the young dis- 

 lome encysted in crayfish. 



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

 hnuts 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, 0.186 mm., acetabulum 0.62 mm. in diameter. Prepharynx longer than pharj-nx or 

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

 pharynx. Testes obhque in 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 11 n. 



Type species Protenteron diaphanum Stafford 1904. 



Intestine of Amhloplites rupestris; Montreal, Canada. 



123(120) Intestinal crura extend beyond acetabulum 124 



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



Centr ovarium 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, in center 

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

 testes. 



Only species known. 



Centrovarium lohotcs (MacCallum) 1S95. 



DeHcate worms, i to ,s mm. long. Suckers relatively small and 

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

 fluent imparting a tubular appearance to the organ. Eggs very 

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



Intestine of Esox lucius, Stizostrdion vitrcum, Ambloplitrs 

 rupestris, Ani^uilla rlirysvpa : Ontario. Canada. 



Fig. 696. Centrovarium lobotcs. Dorsal view. Magnified. (After 

 MacCallum.) 



