Vol. LI. November, 1926. No. 5. BIOLOGICAL BULLETIN THE FLAGELLATE FAUNA OF THE CCECUM OF THE STRIPED GROUND SQUIRREL, CITELLUS TRIDECEMLINEATUS, WITH SPECIAL REFERENCE TO CHILOMASTIX MAGNA SP. NOV. ELERY R. BECKER, IOWA STATE COLLEGE. The intestinal protozoan fauna of the rat, mouse, guinea pig and rabbit has been investigated quite extensively. Not so much has been done on field rodents as on those which lend themselves to laboratory use. In the autumn of 1925 and spring of 1926 the writer made a study of the protozoa harbored in the alimentary tract of the striped ground squirrel, Citellus tridecemlineatus . This rodent was found to be quite as rich a field for investigation of protozoan parasites as the aforementioned animals. The protozoa so far found to be residents of the ccecum of the striped ground squirrel comprise one species of amoeba, Endamceba citelli; one species of Chilomastix; two species of Trichomonas , one of them probably new; one species of Tetratrichomastix, subgenus of Eutrichomastix; one species of Hexamitus; and a flagellate which is either a species of Hexamitus or Urophagus. In the small intestine a Giardia was found. Endamceba citelli, and its pathogenic parasite, Sphxrita endamosbss, were described by the writer (1926) in a previous paper. The Giardia was sent for identification to Dr. R. W. Hegner, who found it to be a new species.* The Chilomastix, Trichomonas, Tetratrichomastix, and Hexamitus will be reported upon in this paper in the order named. The preparations of the other flagellate were not entirely suitable * Since this paper went to press a paper by Dr. R. W. Hegner has appeared in which this Giardia is described. See Hegner, R. W. 1926. Giardia beckeri n. sp from the ground squirrel and Endamceba dipodomysi n sp. from the kangaroo rat Jour. Paras. 12: 203-206. 19 287
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