Introduction 



No single work exists in which the trematode information of the Pacific 

 Northwest has been gathered together. For those who deal with the parasites, 

 their hosts, or the diseases of domestic and game forms, such a work will 

 greatly reduce the time that must be spent in searching. Much of the informa- 

 tion has previously been sought out in this laboratory; therefore, it seemed 

 desirable to complete and publish a catalog. This monograph is the result. 

 In it are included all records of trematodes from the Pacific Northwest with 

 notes about each species, whenever additional information exists. 



The authors are primarily interested in the digenetic trematodes and 

 the original plan was to catalog only that group. However, much monogenetic 

 trematode information is included in the same literature; the list of known 

 monogenetic trematodes is relatively short; so it seemed advisable to extend 

 our work to include this group. 



Also, the catalog was to be limited to parasites of the state of Oregon, 

 but further reflection encouraged us to include the entire Pacific Northwest; 

 i. e. Washington, Oregon, Idaho, and British Columbia. There were several 

 reasons for this decision. Political subdivisions are readily utilized because the 

 borders are clearly defined and understood and because distributional records 

 are reported by political areas. This area by reason of climate and drainages 

 constitutes a fairly distinct zoogeographical region. 



The decision to eliminate California was based on several considerations: 

 first, the fact that little is known of the trematode fauna of Northern Cali- 

 fornia, especially in the area close to the Oregon border. Ingles (1936) con- 

 sidered the trematodes of amphibians of Northern California and Haderlie 

 (1953) the trematodes of fishes of Northern California; but with the excep- 

 tion of these and a few short papers, nothing is known of the trematode 

 fauna. Furthermore, the centers of trematode research have been in Berkeley, 

 Stockton, and Dillon Beach, several hundred miles from Oregon; and trema- 

 tode records tend to be concentrated in those areas. Many of the older records 

 are listed only by state (or territory) and records from Southern California 

 are not easily separated from those near the Oregon border. Furthermore, 

 the trematode fauna of Southern California is quite dififerent from that of 

 the Pacific Northwest. Therefore, we have not included any California records. 



Idaho was included because the center of trematode research, the Uni- 

 versity of Idaho at Moscow, is located only three miles from the Washington 

 state line. Many of the trematodes reported from Idaho have also been re- 

 ported from Washington, Oregon, and British Columbia. 



For British Columbia and Washington an almost identical marine trema- 

 tode fauna has been reported. This, of course, is due to the close proximity of 

 the areas of trematode research; Friday Harbor in the vSan Juan Islands of 

 Washington, Nanaimo on Vancouver Island, and Vancouver on the mainland 

 of British Columbia, all within 60 miles of each other. 



