Parasitology, Harold W. Manter Laboratory of


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Journal of Parasitology (September 1919) 6(1): 11-18, + 2 plates.


Public domain material.


The monostomes are among the least known of North American trematode groups. Records give descriptions of only six species, each the single representative of a genus, and according to the classification of Ward (1918) belonging to four different families. Existing descriptions in most cases are far from complete and data necessary for taxonomic determination are lacking. This deficiency has been pointed out by other workers, both in this country and in Europe, and the classification of the monostomes is not well established. In fact, certain investigators regard them as aberrant forms, sprung from different distome groups, which alike have lost the acetabulum. If this is true and the similarity is merely superficial, the present system of classification must be entirely revised. Careful, complete descriptions of these forms are necessary to provide the data for a natural system of classification. The present study, it is hoped, will prove a step toward the solution of this problem.


The present study demonstrates the specific identity of Heronimus chelydrae MacCallum and Aorchis extensus Barker and Parsons. It confirms the work of MacCallum and includes many additions to the description of the species. The course of the uterus is traced and the position, extent and atrophy of the testis is demonstrated. The wide distribution of the species, and its infestation of six different species of turtles, are items of interest and importance.

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