50 



NOKTH AMEBIC AN FAUITA. 



[No. 36. 



REITHRODONTOMYS FULVESCENS DIFFIOILIS Merriam. 



Orizaba Harvest Mouse. 



(PI. II, fig. 8; PI. V, fig. 8.) 



? ? Reithrodon sumichrasti De Saussure, Rev. Mag. Zool., 2d Ser., XIII, 1861, p. 3.^ 

 Ochetodon mexicanus Coues, Proc. Acad. Nat. Sci. Phila., 1874, p. 186; Mon. N. Am. 



Rodentia, 1877, pp. 128-130. (Not Reithrodon mexicanus Sauss.) 

 Reithrodontomys mexicanus Allen, Bull, Am, Mus. Nat, Hist., VII, 1895, p, 135; IX, 



1897, p. 199 (not Reithrodon mexicanus Sauss). 

 Reithrodontomys dijfficilis Merriam, Proc, Wash, Acad. Sci., Ill, 1901, p, 556, 



Type locality. — Orizaba, Vera Cruz. 



Distribution. — Interior mountain slopes along the southern end of 

 the Mexican table-land in the States of Vera Cruz and Puebla. 



Characters. — Similar to tenuis j but colors decidedly darker; ears and 

 tail blacker, and underparts more ochraceous. 



Color. — ^Upperparts pinkish cinnamon mixed with blackish brown, 

 in some specimens the brown prevailing, in others the cinnamon; 

 sides of face and body usually clear pinkish cinnamon, though in 

 certain worn or immature specimens this color is nearly absent; 

 ears fuscous or sepia, usually with more or less tawny hairs on inner 

 surface; tail fuscous above, grayish white below; underparts grayish, 

 with a strong wash of light pinkish cinnamon, the latter color pre- 

 vailing in the majority of the individuals; feet grayish white; ankles 

 dusky. 



Slcull. — Closely similar to that of tenuis; braincase averaging a 

 trifle broader. Compared with R. megalotis saturatus: Skull shorter 

 and relatively broader, with shorter nasals and broader interptery- 

 goid fossa. 



Measurements. — ^Average of 5 (subadult) from type locality: 

 Totallength, 170 (162-177); tail vertebrae, 96.6 (88-101); hind foot, 

 19.5 (19-20). Adult from Maltrata, Vera Cruz: 172; 97; 21. Skull: 

 (See table, p. 81). 



Remarl<:s. — This is the darkest of the races oifulvescens. Although 

 rather restricted in range, it is a weU-marked form, easily di&tin- 

 guished from tenuis by its darker colors, but intergradation is clearly 

 shown by specimens from the coast region of Vera Cruz (Carrizal 

 and Santa Maria). From R. megalotis saturatus, the range of which 

 is- adjacent to that of difficilis in Vera Cruz, it differs in more tawny 

 coloration, ochraceous instead of grayish underparts, and smaller 

 and paler ears. 



1 When the type of R. "sumichrasti'' can be compared with modern material it may be possible to 

 identify the species and use the name. I have seen photographs of the type skull, which clearly show it to 

 belong in the typical subgenus, and the original description agrees best with the present form; but as no 

 definite t3rpe locality is assigned and the description is inadequate for subspecific determination, it seems 

 best to let the name remain in synonymy. 



