THE TREMATODE PARASITES OF MARINE MAMMALS By Emmett W. Pkice Parasitologist, Zoological Division, Bureau of Animal Industry United States Department of Agriculture The internal parasites of marine mammals have not been exten-sively studied, although a fairly large number of species have been described. In attempting to identify the trematodes from mammals of the orders Cetacea, Pinnipedia, and Sirenia, as represented by specimens in the United States National Museum helminthological collection, it was necessary to review the greater part of the litera-ture dealing with this group of parasitic worms. In view of the fact that there is not in existence a single comprehensive paper on the trematodes of these mammals, and that many of the descrip-tions of species have appeared in publications having more or less limited circulation, the writer has undertaken to assemble descriptions of all trematodes reported from these hosts, with the hope that such a paper may serve a useful purpose in aiding other workers in de-termining specimens at their disposal. In addition to compiling the descriptions of species not available to the writer, two new species, one of which represents a new genus, have been described. Specimens representing 10 of the previously described species have been studied and emendations or additions have been made to the existing descriptions; in a few instances the species have been completely reclescribed. Three species, Distoinwni pallassil Poirier, D. vaUdwim von Lin-stow, and D. am/pidlacewni Buttel-Reepen, have been omitted from this paper despite the fact that they have been reported from ceta-ceans. These species belong in the family Hemiuridae, and since all species of this family are parasites of fishes, the writer feels that their reported occurrence in mammals may be regarded as either errors of some sort or cases of accidental parasitism in which fishes have been eaten by mammals and the fish parasites found in the mammal post-mortem. Buttel-Reepen (1902) has pointed out, in connection with the reported occurrence of D. ampullaceum in a cetacean, that sailors commonly designate species of mackerel as "Delphin" or "Dolphyn (holliindisch)." It appears likely, there-No. 2936— Proceedings U. S. National Museum, Vol. 81. Art. 13 118893—32 1 1
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