253] NORTH AMERICAN MONOSTOMES 35 



13(10) Sucker larger than the pharynx 15 



14(15) Vitellaria strongly developed, extending to inner wall of 



intestine; ratio of testes to ovary 2:1 



Cyclocoelum macrorchis nov. spec. 



15(14) Vitellaria weakly developed, rarely reaching middle of 



crura; ratio of testes to ovary 2:1 



Cyclocoelum vicarium (Arnsd.) 



16(9) Testes unequal in size 18 



17(20) Oral sucker twice as large as pharynx 19 



18(19) Ratio of posterior testis to ovary 2:1 



Cyclocoelum ohscurum (Leidy) 



19(18) Ratio of posterior testis to overy 3:1 



Cyclocoelum ovopunctatum Stoss. 



20(17) Oral sucker not twice the size of pharynx. Ratio of poste- 

 rior testis to ovary 3:1 Cyclocoelum problematicum Stoss. 



21(8) Genital glands contiguous, not separated by uterine loops. . .24 

 22(25) Testes unequal in size; oral sucker twice as large as pharynx 25 



Cyclocoelum wilsoni nov. spec. 



24(23) Ratio of posterior testis to ovary 2:1 



Cyclocoelum tringae (Brandes) 



25(22) Testes equal in size; oral sucker and pharynx approximately 



equal. Ratio of testes to ovary 10:7 



Cyclocoelum triangularum nov. spec. 



26(7) Uterus passing dorsally over intestinal crura and vitellaria 

 to body wall; vitellaria moderately developed, rarely ex- 

 tending beyond middle of crura 30 



27(28) Sucker \]/2 times pharynx; testes unequal; ratio posterior 



testis to ovary 3:2 Cyclocoelum brazilianum Stoss. 



28(29) Sucker and pharynx equal in size; testes equal; ratio of 



testes to ovary 2:1 Cyclocoelum halli nov. spec. 



Description of species 



CYCLOCOELUM LEIDYI nov. spec. 



[Figures 1, 2, ZZ] 



Syn: Monostomum mutabile Leidy 1885, nee Zeder 1800 



This collection contains five specimens described by Leidy (1885) as 

 follows: "From the thoracic cavity of a Gray Snipe, Gallinago wilsoni, 

 Dr. Warren (of Westchester) obtained five Flukes, 18mm long, by 4mm 

 broad. These appear to be Monostomum mutabile." 



These specimens are readily recognized as belonging to the genus 

 Cyclocoelum Brandes (1892) but are distinctly different from Cyclocoelum 

 mutabile and represent a new species. The following description shows the 

 characteristic differences between the two species. 



