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600 THE MONTHLY BULLETIN. 



KEY TO THE GROUND SQUIRRELS OF CALIFORNIA. 



Size large: body alone more than 9 inches (228 mm.) long; tail more than 6 inches 



(152 mm.), not counting hairs; ears tall and rather pointed; tail bushy. 

 2. A blackish brown wedge-shaped patch on middle of back between shoulders 



Douglas Ground Squirrel (p. 52). 



2'. No blackish patch on back. 



3. Tail longer: without hairs, about 8 inches (203 mm.); no sharply defined 



triangular whitish patch on each shoulder Rock Squirrel (p. 58). 



3'. Tail shorter: without hairs, Ih inches (190 mm.) or less; a more or less 

 sharply defined triangular whitish patch on each shoulder. 

 4. Size larger: body alone more than 10| inches (273 mm.) long; general 



tone of coloration darker Catalina Island Ground Squirrel (p. 49). 



4'. Size smaller: body alone less than 101 inches (273 mm.); general tone 

 of coloration lighter. 

 5. Coloration pale in general tone, near light cinnamon-drab; shoulder 



patches clear silvery white and more extensive 



Fisher Ground Squirrel (p. 44). 



5'. Coloration somewhat darker, near wood brown; shoulder patches 



duller white and less extensive California Ground Squirrel (p. 9). 



Size medium or small: body alone less than 9 inches (228 mm.); tail less than 

 6 inches (152 mm.), not bushy; ears low and rounded, or else reduced to mere 

 rims. 

 6. Body with conspicuous lengthwise stripes; coloration varied. 



7. One white stripe on each side of body; under side of tail conspicuously 

 white; head not more or less yellowish or coppery. 

 8. Smaller: body alone 6 inches (152 mm.) or less; general coloration 



grayish drab Desert Antelope Ground Squirrel (p. 94). 



8'. Larger: body alone 6 J inches (158 mm.) or more; general coloration light 

 clay color. 

 9. Size slightly greater; tone of color slightly darker, more deeply clay 



color Nelson Antelope Ground Squirrel (p. 103). 



9'. Size slightly less; tone of color slightly paler, more buffy 



Los Banos Antelope Ground Squirrel (p. 110). 



7'. Three stripes on each side of body, one white and two black; head more or 

 less yellowish or coppery. 

 10. Tail longer: without hairs, about 3J inches (89 mm.). 



11. Tone of coloration lighter; middle of back more of an ashy brown 



Inyo Golden-mantled Ground Squirrel (p. 89). 



11'. Tone of coloration darker; middle of back more of a cinnamon- 

 brown Sierra Golden-mantled Ground Squirrel (p. 83). 



10'. Tail shorter: without hairs, about 3| inches (79 mm.) 



San Bernardino Golden-mantled Ground Squirrel (p. 92). 



6'. Body without any stripes: general coloration nearly or quite uniform. 

 12. Size larger: body alone more than 7 inches (178 mm.). 



13. Larger: body about 85 inches (216 mm.); middle of back not bright 



reddish-brown, but grayish-brown — Oregon Ground Squirrel (p. 59). 

 13'. Smaller: body about 7i inches (198 mm.); middle of back bright 



reddish-brown Belding Ground Squirrel (p. 67). 



12'. Size smaller: body alone less than 7 inches (178 mm.). 



14. Tail round and relatively long: over 3 inches (76 mm.). 



15. Tone of coloration paler, light pinkish-cinnamon 



Yuma Round-tailed Ground Squirrel (p. 76). 



15'. Tone of coloration darker, wood brown 



Death Valley Round-tailed Ground Squirrel (p. 80). 



15". Tone of coloration medium, grayish-brown or avellaneous 



Palm Springs Round-tailed Ground Squirrel (p. 81). 



14'. Tail flat-haired and relatively short: under 3 inches (76 mm.). 



16, Under side of tail pinkish-buff; rim of ear distinct though low 



Stephens Soft-haired Ground Squirrel (p. 73). 



16'. Under side of tail white; rim of ear scarcely discernible above 

 general surface of head Mohave Ground Squirrel (p. 75). 



Note. — Figures indicating page numbers refer to folios at foot of pages. 



