298 BULLETIN 56, UNITED STATES NATIONAL MItSEUM. 



The gToiiiul squirrels of the United States and Mexican Boundary 

 region may be determined by means of the following: 



KEV TO GKOUND-SgUIRRELS FOUND ON THE MEXICAN BOIXDAHY LINE, BASED ON EXTERNAL 



CHARACTERS. 



a. Above lonsitudinally striped, or spotted In longitudinal series, forniini^ inter- 

 rupted stripes. 

 h. Stripes continuous. 



c. With one white stripe on each side. 

 (1. Tail white l.elow. 



r. Caudal hairs with one free black band. 



Ammoapcnnophiliis Iriiriinis (p. 200) 

 ce. Caudal hairs with two free black bands. 



AiiiiiKisiK'ruiophiJKS leiicunis hitrrprrs (p. 301) 

 (1(1. Tail iron gray below. 



f. Coloration dark ; length of caudal vertebne, 80 nini. 



AiiiiiKJ.spci-iiiopliilits liiirriitii (p. 303) 

 ff. Coloration pallid; length of caudal vertebrie, 05 nun. 



AnuiiospcniioitJiihis iKirrisii saxicola (p. 300) 

 cc. With three stripes on each side, one white and two black. 

 //. Tail all grayish or vinaceous above. 



Callospcfiiiopliiliis hitrralis (\). 300) 

 ////. Tail with tcniiinal half black above. 



('(ilhtspriiiiophiltis hcrii(ir(1i)iiis (p. 313) 

 bh. Stripes interrupted, composed of lines of spots or of stripes containing 

 rows of spots. 



/(. Larger: length more than 280 nun. 



/. Color olivaceous gray: tail flattened, long, and bushy. 



CitrJIiis { /ctoiloiiioidrft) jiir.riraiiKs parridriift (]». 328) 

 //. Color soiled yellowish: tail subcylindrical, with i-ather short 

 ha ins. 



Citellii-'^ ilctUloiiius) tridcccniliiicatiis tcrcitsifi (p. 327) 

 ///;. Smaller; length less than 28(( mm. 

 j. Tapper surface pale grayish brown. 



('UrUiiH ( XcrositeniioitJiiliix) s/tilosoiiia aiiiircfnii< (p. 332) 

 jj. Upper surface russet vv vinaceous cinnamon, 

 /r. Color ])allid: spots small. 



Citcll)!)^ { XcrospciiiKipltiliis) si)ilos<jiua arcns (p. 331) 

 kJx. Color dark ; s])ots large. 

 Citclliis {Xcro.-!pcnii(jp}iihi.<<)spil(ts())ii(t inaciospiloiiis (p. 3.33) 

 aa. Above not distinctly striped or spotted in longitudinal series. 



/. Form s(piirrel-like ; ears high ; tail flattened and bushy. 

 m. Smaller: length, 410 mm.; tail, 170; hind foot. 55. 

 A triangular patch of silver gray above shoulder; 

 six pairs of mannnary teats. 



Otoxocrmophilus hcrcJicjii (p. 324) 

 mm. Larger : length, 400 mm. ; tail, 220 ; hind foot. 02. 

 No triangular patch above shoulder ; five pairs of 

 mammary teats. 

 11. Color of mantle grayish. 



Otof^permophihis grammnrus (p. 315) 

 nn. Color of mantle black. 



Otospcniiophiliifi f/rammurus hucklei/l (p. 323) 

 11. Form weasel-like: ear-conch minute'j tail terete. 



Citrlliis (Xcrosprniiopliihis) fercficaiKhtft (p 336) 



