1914.] 



EEITHEODOIsTOMYS MEXICANTJS GROUP. 



71 



Measurements. — Adult male (Jalapa, Vera Cruz): Total length, 197; 

 tail Yertebrse, 119; hind foot, 21. Average of 2 adults from Toton- 

 tepeC; Oaxaca: 193; 117; 21. Average of 3 adults from Jacalte- 

 nangO; Guatemala, and Tumbala, Chiapas: 194; 117; 20.2. Skull: 

 (See table, p. 81). 



Remarks. — This species, although described over 50 years ago, is 

 still imperfectly known, and the name mexicanus has been misapplied 

 by all authors since De Saussure. Three distinct species of Reithro- 

 dontomys occur in the mountains of Vera Cruz and a fourth (R, 

 megalotis saturatus) not far away on the table-land. These (using the 

 modern names) are R. rufescens rufescens, R. fulvescens difficilis, and 

 R. "cherrii jalapse.'^^ 



The original description^ is so complete and agrees so perfectly with 

 the last of these that there appears to be not the shghtest doubt that 

 the species now known as ''jalapx'^ should be referred to mexicanus. 

 The combination of tawny upperparts, white belly, dark feet, and 

 unicolor tail is possessed by no other species in this region. 



Through the kindness of M. Maurice Be dot, director of the Geneva 

 Museum, who has furnished the Biological Survey with photographs 

 and measurements of the type skull, I am able to present additional 

 evidence corroborative of the above decision. The photographs 

 clearly show the relatively narrow outer wall of the anteorbital fora- 

 men and the broad interpterygoid fossa, characteristic of the sub- 

 genus Aporodon, and the measurements agree closely with those of 

 specimens of "jalapse" from Jalapa, Vera Cruz. 



The type of R. mexicanus, with the skull inside the skin, was bor- 

 rowed in 1890 from the Geneva Museum and examined in Washington 

 by Drs. Allen, Merriam, and True. Comparison was made with a 

 specimen ^ (No. 7007a, U . S. Kat. Mus.) from Tehuacan, Puebla, at that 

 time practically the only available specimen from southern Mexico. 

 Dr. Allen in referring this specimen to mexicanus stated that it agreed 

 with the type.* Dr. Merriam's notes, however, taken at the same 

 time, indicate some important differences. These are as follows: 



No. f^. This specunen is the type of De Saussin-e's description. Measure- 

 ments. — ^Hind foot, 18.5. Ear from crown, 10; from anterior base, 13. The upper- 



1 All of these have been taken at Jalapa, Vera Cruz. 



2 Following is a translation of the pertinent portions: 



"The size of this animal is nearly exactly that of the European field-mouse (Mus silvaticus), though its 

 forms are somewhat more thick set. * * * Tail very long, its length exceeding that of the body and 

 head. The color of the pelage is tawny brown, on the sides becoming absolutely tawny, or even orange- 

 tawny. The tawny color becomes fainter toward the line where it comes in contact with the white of the 

 belly. The lips, lower part of cheeks, chin, throat, and entire underparts are almost pure white, here and 

 there slightly washed with a tawny tint, especially on the breast and throat. * * * The hairs are slate 

 gray, the tips only passing into russet, or white. The ears are brown * * *. The fore feet are white, 

 except above, as far as the root of the digits, where they are gray. The tail is blackish, scaly, unicolor, and 

 covered with rather dark gray hairs; it is especially hairy toward the tip; at its base the hairs are scanty 

 and very short; but they become longer toward the tip.'' 



3 Referred by the writer to E. fulvescens difficilis. 



4 BuU. Am. Mus. Nat. Hist., VII, 1895, p. 136. 



