Reports of the cestode genus Catenotaenia in North American hosts are quite meager. Apparently only two species, Catenotaenia linsdalei McIntosh and C. pusilla (Goeze, 1782), have been described and reported from several rodents in North America (McIntosh, 1941; Joyeux and Baer, 1945; Voge, 1948; Chandler and Melvin, 1951). Recent examination of some cestodes from the Panamint Kangaroo Rat, taken in Southern California by Mr. D. J. Doran,2 revealed that this rodent also harbors a Catenotaenia species. Direct comparison of the writer's mnaterial with tihe type specimen of C. linsdalei McIntosh, kindly loanied by Dr. E. W. Price, Curator of the Helminthological Collection, United States National Museum, and with a specimen of C. pusilla (Goeze, 1782) kindly loaned by Dr. A. C. Chandler, indicated that the worms from the Panamint Kangaroo Rat represented a different species. Comparison with the published descriptions of other members of this genus showed that thc present material represents a new species. A description follows: Catenotaenia californica, sp. nov. Strobila thin and of moderate length, ranging from 261/2 mm. to 82 mm. in length and 3.3 mm. in maximum width. The mature proglottid is usually longer than broad, averaging 0.996 mm. by 0.922 mm., however, this nearly square shape varies rapidly in both directions along the strobila, the segments being broader than long anteriorly and longer than broad posteriorly. The mature proglottids range in size from 0.748 to 1.13 mm. in width by 0.870 mm. to 1.26 mm. in length. The gravid proglottids vary from 1.25 to 3 times as long' as broad; the length ranges from 1.85 to 3.3 mm. (average 2.68 mm.), and the width ranges from 1.13 mm. to 1.65 mm. (average 1.43 mm.). The proglottids are individually wider posteriorly than anteriorly and are markedly craspedote in both living and preserved specimens. The scolex ranges from 150 g to 200 /A in diameter (averages 181 ,u). A rostellum and hooks are lacking. Four shallow suckers are present. The outside diameter of the suckers ranges from 68 A to 110 u (average 88.8 A), and the inside diameter ranges from 30 A to 70 A (averages 53.6 ,u).