288 ELERY R. BECKER. 



for critical study, and the specimens were very scarce. Conse- 

 quently a description of this species (Hexamitus or Urophagus) 

 must be delayed until more suitable material is obtained. Twenty 

 ground squirrels in all were examined for protozoa. All save one 

 harbored infinite numbers of protozoa in the coecum. This one 

 had only a light infection. 



The technique consisted of a careful microscopic examination of 

 thin emulsions of the coecal contents in normal salt solution. 

 Permanent prepared slides were made by Heidenhain's iron- 

 haematoxylin staining after fixation in Schaudinn's solution. 



Chilomastix magna sp. nov. This protozoan was found in all 

 twenty ground squirrels. The shape is essentially like that of 

 Chilomastix mesnili from man, pyriform with three flagella at the 

 broadly rounded anterior end. There is often a tuft of short 

 bristly cuticular projections in the region of the flagella (Fig. i). 

 It may be present in either living or stained material, and is not 

 a fixation artefact. Fixed and stained individuals measured from 

 10 to 21.6 micra in length and from 6 to u micra in width, the 

 average width being about 9 micra. The length of Chilomastix 

 mesnili, as given by Kofoid and Swezy (1920) is from 9.6 to 15 

 micra in stained preparations. The writer measured a number of 

 Chilomastix mesnili on slides which he had prepared, and found 

 a range of from 7 to 1 1 micra. When one considers that twenty 

 out of thirty specimens of Chilomastix magna measured from 15 

 to 21.6 micra, it will be seen that this flagellate is almost twice as 

 long as the one found in the intestine of man. 



A study of the cytology of this protozoan promised to be 

 particularly interesting because of the discrepancies between the 

 accounts of Chilomastix mesnili by Kofoid and Swezy (1920) and 

 Dobell and O'Connor (1921). The latter authors are particularly 

 outspoken in flatly denying the existence of certain cell structures 

 which the former claim to have seen. Without desiring to 

 become in any way involved in the controversies of these writers, 

 the writer must state that his observations agree more nearly with 

 those of Kofoid and Swezy, although his interpretations may 

 differ in certain respects. The morphology of the free form, 

 cyst, and dividing individuals will be described. 



The nucleus of the free form lies in the extreme anterior end of 



