267] NORTH AMERICAN MONOSTOMES 49 



and bile ducts of the muskrat while the Notocotylidae are normally 

 inhabitants of the intestine and rectum. It is not impossible that a Noto- 

 cotylid species may have ascended the gall-duct of this host and become 

 modified and adjusted to the new conditions. Yet on the basis of the facts 

 noted above the writer cannot agree with the opinion of Barker regarding 

 the Notocotylid character of these worms. 



More recently Hassall (Stiles & Hassall 1894) collected from Arvicola 

 riparius and Fiber zibethicus taken in Maryland in 1892 specimens deter- 

 mined as Monostomum sp. and one year later from Aix s pons a and Dafila 

 acuta worms also determined as Monostomum sp. On observation and 

 study by the writer the specimens taken from Aix sponsa, Dafila acuta 

 and Fiber zibethicus have been found to be distinctly different from forms 

 previously described and on the basis given in a later section must be 

 recognized as a new species. On account of the similarity to the immature 

 stages of Cercaria urbanensis Cort it is believed to be the adult form of this 

 species. The material taken from Arvicola riparius has been found to 

 agree with Notocotylus quinqueserialis (Barker and Laughlin 1911). Other 

 American records are those of Barker (1915, 1916) in which he records 

 Catatropis filamentis from Fiber zibethicus taken in Nebraska and Nudoco- 

 tyle novicia from the same host taken in the same region. 



Additional records presented in this paper are Notocotylus urbanensis 

 (Cort 1914) from the black and domestic swan taken at Golden Gate 

 Park, San Francisco, California by John C. Johnson in February 1919 and 

 Paramonostomum echinum nov. spec, from the intestine of Fiber zibethicus 

 taken at Wray, Colorado by C. H. Gable, October 1916. 



DIAGNOSIS OF FAMILY 



Small monostomes tapering at both ends, posterior end broadly 

 rounded, anterior slightly more attenuated. Generally with rows of papil- 

 lae formed of unicellular dermal glands. Esophagus short, without 

 pharynx; intestinal ceca with short diverticula, extending entire length of 

 body. Genital pore median, except in Nudocotyle where it is distinctly 

 lateral, usually near oral sucker. Cirrus sac elongate. Testes symmetrical, 

 extracecal, near posterior end. Ovary between testes. Vitellaria lateral, 

 anterior to testes. Uterine coils between cirrus sac and genital glands, 

 transverse, regular, usually not extending outside intestinal crura. Eggs 

 small with long p olar filament on each end. 



KEY TO SUBFAMILIES AND GENERA 



1(5) Genital pore anterior median. . .Sub-family Notocotylinae . . 2 



2(5) With ventral glands 3 



3(4) Ventral glands protrusible Notocotylus Diesing 1839 



4(3) Ventral glands not protrusible Catatropis Odhner 1905 



