THE ADULT TAENIOID CESTODES OF DOGS AND CATS, AND OF RELATED CARNIVORES IN NORTH AMERICA. By Maurice C. Hall, Senior Zoologist, Umted States Bureau of Animal Industry. INTRODUCTION AND SUMMARY. The literature bearing on the subject of tapeworms parasitic in dogs and other carnivores is extensive, but because it is scattered in numerous papers the student of these forms is likely to experience considerable difficulty in the determination of specimens, particu-larly in the case of tapc^Yorras from wild carnivores. Heretofore there has not been available a comprehensive discussion of the sub-ject in a single paper. The present paper includes descriptions of all the adult tapcAvorms of the superfamily Taenioidea known to occur in dogs, cats, and re-lated carnivores in North America, together with species of the same superfamily not yet recorded as present in North America, but found in other parts of the world, and liable to occur in carnivores in this country. Supplementing the descriptions are keys for the determination of specimens, a list of hosts, and a bibliography. The illustrations, whether original or copied, were made by Mr. W. S. D. Haines, artist of the United States Bureau of Animal Industry. Lynx uinta is recorded as a new host for Taenia taeniaeformis. Taenia macrocystis is newly recorded for North America, having been collected from Lynx ru-ffus and L. haileyi. Taenia pisiformis (larval stage) is newly recorded from Lepus califoimicus toalla-waUa, Sylvilagus -floridanus mearnsii, S. auduhoni haileyi^ and mountain beaver. Taenia novella Neumann, 1896, is regarded as synonymous with T. pisiformis instead of with T. laticoUis as Liihe (1910) believed. Taenia pisiformis frequently shows more than the 8 to 10 lateral uterine branches commonly stated in the literature as characteristic of this species. As many as 14 may be present. New hosts for Taenia hydatigena are the Bharrel (National Zoo-logical Park) , Columbia deer, Odocoileus hemionus, Rangifer terrae-Proceedinqs U. S. National Museum. Vol. 55— No. 2258. 62055— 20— Proc.N.M.Vol.55 2 1