229] NORTH AMERICAN MONOSTOMES 11 



In North America little has been done on this group of trematodes and 

 aside from the systematic arrangement of species by Pratt (1902) and the 

 descriptive key of Ward (1918) only isolated descriptions of species have 

 appeared. The earliest report of species which have been assigned to this 

 group are those of Joseph Leidy (1856-1895) the descriptions of which are 

 so meager that some of the forms must remain as species inquirendae. 



MacCallum (1902) found and described Heronimus chelydrae from the 

 lungs of the snapping turtle. Barker and Parsons fifteen years later re- 

 described this form without reference to the work of MacCallum under the 

 name Aorchis extensus. Barker and Laughlin (1911) described Notocotyle 

 quinqueser talis from the intestine of Fiber zibethicus and later Barker (1916) 

 described from the same host the new genus and species Nudocotyle novicia. 

 These with the report by Cole of Mono stoma jab a (later named Collyricum 

 colei by Ward) are the major items from North America. More recently 

 Stunkard (1919) has shown that Heronimus chelydrae of MacCallum and 

 Aorchis extensus of Barker and Parsons are identical, and Tyzzer (1918) 

 from the study of Collyriclum colei Ward and comparison of it with the 

 description of Collyriclum faba Bremser by Kossack, provisionally regards 

 them as identical. Tyzzer's paper affords a detailed account of the 

 anatomy of this species and a study of the maturation, fertilization and 

 development of the miracidia within the eggs. His views regarding the 

 identity of the two forms are discussed in detail later (p. 62-65). 



SPECIES PREVIOUSLY DESCRIBED FROM NORTH AMERICA 



Most descriptions of North American species of this group are inade- 

 quate and as a result of this it is impossible to determine with any degree 

 of accuracy their rightful systematic position without re-examination of 

 the material. This has been lost in a number of cases and in other instances 

 all effort to locate certain specimens has proved futile. The following list 

 is an attempt to bring together all references to date on the species pre- 

 viously described from North American fresh water hosts. Names in- 

 dented represent later descriptions of the same form arranged in chrono- 

 logical order. 



Monostomum ornatum Leidy 1856:43 



Monostomum ornatum Brandes 1892:504-510 

 Haematoloechus? Stafford 1902:724 



Monostomum incommodum Leidy 1856:43 

 Distoma oricola Leidy 1884:47 

 Distoma oricola Leidy 1891:414 



Monostomum affine Leidy 1858:43 



Notocotyle? affine (Leidy 1858) Barker 1916:183 



