62 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



Mr. Colburn worked, he securing only four specimens during six weeks 

 of constant trapping. 



Genus REITHRODON Waterhouse. 



Reithyodon Waterhouse, P. Z. S., 1837 (Nov. 21, 1837), 29; Zool. Voy. 



Beagle, Mamm., 1839, 68. No type specified. 

 Reifhrodon Coues, Proc. Acad. Nat. Sci. Phila., 1874, 185. Type, R. 

 cuniculoides Waterh. — Thomas, Ann.& Mag. Nat. Hist. (7), VIII, 

 Sept. 1901, 254. — Allen, Bull. Am. Mus. Nat. Hist, XIX, May, 

 1903. 194 (sub Eiineoniys). 



Variants or emendations are: Ritlirodon Agassiz, 1846; Rheitrodoii 

 Roger, 1887 ; Rhithrodon Flower & Lydekker, 1891. 



The genus Reifhrodon, 2iS originally constituted in 1837, consisted of two 

 species, R. typicus and R. cuniculoides. Later, other species of American 

 Muridas with grooved upper incisors were referred to it, including the 

 North American genus now known as Reithrodontomys, although these 

 two groups have little in common beyond the superficial character of 

 grooved upper incisors. Other species formerly associated with it are the 

 genera Eimeoniys Coues and Sigmoniys Thomas, neither of which prove 

 to have more than a superficial likeness to Reifhrodon as now restricted 

 and as originally constituted. 



Two years later, in 1839, Waterhouse himself added to it a third species, 

 R. chinchilloides, which, proving not to be congeneric with the others, has 

 since become the type of the genus Ettneomys. 



In 1874, Coues (/. c.) divided Reifhrodon into ''Reifhrodon proper," 

 with R. cuniculoides as the type, and Etmeomys, a new subgenus of Reifh- 

 rodon, with R. chinchilloides 2is the type. In 1901, Thomas (/. c.) adopted 

 these two divisions as full genera, and, having previously removed his 

 Reifhrodon alsfoni as the type of a new genus Sigmomys, ^ arranged the 

 " South America groove-toothed Muridae" in three genera, Reifhrodon, 

 Enneomys and Sigmomys, which really have little in common. Later a 

 somewhat detailed comparison of Reifhrodon and Enneomys was given by 

 the present writer.^ 



The genus Reifhrodon is represented by four species and an additional 

 subspecies, and, so far as known to me, is restricted to Patagonia, Argen- 



' Ann. & Mag. Nat. Hist. (7), VIII, Aug., 1901, p. 150. 

 ^Bull. Am. Mus. Nat. Hist., XIX, 1903, pp. 194, 195. 



