1914.] 



GENUS EEITHKODONTOMYS. 



13 



pelage covering the anterior half of the body. As in the previous 

 instance, the new pelage is darker and more ochraceous (less reddish) 

 than the old. In both examples it will be noticed that the progress 

 of the molt is directly the reverse of the normal autumn molt, the 

 rump being the last part of the body to be invested, instead of the 

 first, as in the usual method. 



The molting period of the species inhabiting Mexico and Guatemala 

 is less strictly confined to the autumn, but as a general rule (with 

 many exceptions) individuals taken from December to June show a 

 fuller and fresher pelage than those taken in the other half of the 

 year. In the entire collection from Mexico I have been able to find 

 only two specimens showing a clearly marked molting line. These 

 are both adult males of E. megalotis alticolus, taken at La Parada, 

 Oaxaca (in the lower edge of the Transition Zone), August 19, 1894. 

 In these the molt is nearly completed, the new pelage covering the 

 anterior portion of the body to the rump. 



Genus REITHRODONTOMYS GiglioU. 



Reithrodon Leconte, Proc. Acad. Nat. Sci. Phila., 1853, pp. 410, 413; Baird, Mamm. 

 N. A., 1857, p. 447. (Not Reithrodon Waterhouse.) 



Reithrodontomys GiglioU, Ricerche intorno alia Distrib. Geog. Gener. <;Boll. Soc. 

 Geog. Ital., Roma, XI, May-July, 1874, p. 326. Author' 3 separates dated 1873 

 (probably dated from first part of paper in Vol. X), repaged, p. 160. (North 

 American members of the genus Reithrodon; no species mentioned.) ^ 



Ochetodon Coues, Proc. Acad. Nat. Sci. Phila., December 15, 1874, p. 184 (no type 

 selected; species included : 0. humilis, 0. longicauda, O.mezicanus, O.montanus, 

 and 0. sumichrasti) . 



Aporodon Howell, postea, p. 63. Type, Reithrodontomys tenuirostris Merriam. 



Remarks. — Since no species were mentioned by Gigholi when he 

 named the genus Reiilirodontomys , the type must be fixed by subse- 

 quent designation. Miller and Rehn ^ have selected Mus lecontii 

 Aud. and Bach. [ = R. Tiumulis] as the type, but this is in violation of 

 Opinion 46 of the International Commission on Zoological Nomencla- 

 ture, which advises that the species first associated with the name be 

 considered the type.^ Allen, in 1893, was the first to use the generic 

 name in connection with a specific name, his paper including three 

 species — R. megalotis, R. aztecus, and R. montanus^ Since both 

 megalotis and montanus were published prior to the naming of the 

 genus, either may be selected as the type. I therefore designate 

 Reithrodon megalotis Baird as the type of the genus ReitJirodontomys. 



GENERIC CHARACTERS. 



Form murine; tail long, always more than one-third, often more 

 than one-half total length, slender, scaly, thinly haired ; ears promi- 



1 Elliot in Pub. Field Columb. Mus., Zool. Ser. Ill, 1903, p. 145, and several times subse(juently, spoils 

 thisi\3,mQ " Rhithrodontomys". 



2 Proc. Boston Soc. Nat. Hist., XXX, 1901, p. 95. 



3 Smittis. Inst., Pub. 2060, February, 1912, p. 104. i Bull. Am. Mus. Nat. Hist., V, 1893, pp. 79-80. 



