Furcocercous Larval Trematodes from San Juan Island, Washington

Abstract

1. Six new furcocercous cercariae from the north-western United States are described and comparisons with similar forms are made.2. On the basis of the structure ofCercaria tuckerensisspec. nov. and three cercariae reported in the recent literature it is possible to characterise more precisely the Elvae group, which now contains eight members.3. The execretory system ofCercaria elvaeMiller, 1923, was re-studied and found to differ from the original description. The bearing of this sort of error on Faust's use of excretory system formulae is touched upon.4.Cercaria burtiMiller, 1923, originally described from northern Michigan, is reported from San Juan Island.5. Certain features of the morphology and biology of the furcocercous cercariae are discussed in the light of this and other recent studies.6. Check List II of the furcocercous cercariae, with eighteen larvae, is given.