PARASITIC FLATWORMS 



79 (74) In each proglottid normally less than three testes. 



443 

 80 



80 (81) Two testes in each proglottid. 



Diorchis Clerc 1903. 



Rostellum with single crown of ten hooks having long dorsal and short ventral roots, or 

 exceptionally very short dorsal root and ventral root nearly as long as the blade. Entire 

 surface of suckers may be armed with minute spines. Inner longitudinal muscle layer con- 

 sisting of 8 bundles, 4 dorsal and 4 ventral. Two testes in each proglottid. Ovary and vitel- 

 larium always median. Adults in birds. 



Four or more species in European water birds. Most of the host species occur in North 

 America. D. acuminata and D. americana were both collected by Ransom from the coot in 

 Nebraska. 



FIG. 749. Diorchis acuminata. a, Hook from rostellum; sexually mature segment; cp, cirrus- 

 pouch; ov, ovary; /, testis; ves sem, seminal vesicle; yg, yolk gland; magnified. (After Ransom.) 



FIG. 750. Diorchis americana. a, Hook from rostellum; magnified; sexually mature segment at 

 high focus to show male organs, dorsal view; magnified; cp, cirrus-pouch; ov, ovary; /, testes; ves sem, 

 seminal vesicle; yp, yolk gland; magnified. (After Ransom.) 



8i (80) One testis in each proglottid. .... . A ploparaksis Clerc 1903. 



_ Strobila small and slender. Rostellum 



armed with a single crown of 10 hooks, with 

 ventral root as long or nearly as long as 

 blade. Suckers unarmed. One testis dorsal. 

 Seminal vesicle large. Ovary and vitella- 

 rium always median. Adults in birds. 



Type species. 

 Aploparaksis filum (Goeze) 1782. 



o f d ,lttfee ssns si **$& ^ 



X 36. (After Clerc.) Hook from rostellum, X 750. all of the species are found in North Amen- 

 (After Krabbe.) can host species. 



82 (71) At least six testes normally in each proglottid 83 



