62 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



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

 of constant trapping. 



Genus REITHRODON Waterhouse. 



/^ezf/t fodou Wsittrhouse, P. Z. S., 1837 (Nov. 21, 1837), 29; Zool. Voy. 



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

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

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

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

 1903, 194 (sub Eitneomys). 



Variants or emendations are : RitJirodon Agassiz, 1846 ; Rheitrodon 

 Roger, 1887 ; Rliithyodon Flower & Lydekker, 1891. 



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

 species, R. typiciis and R. cnniculoides. Later, other species of American 

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

 North American genus now known as Reifhrodoiitomys, 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 Enneoniys Coues and Sigmoniys Thomas, neither of which prove 

 to have more than a superficial likeness to Reithrodon 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 Enneo))iys. 



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

 with A', cnniculoides as the type, and Eujieoniys, 3. new subgenus of Reith- 

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

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

 Reithrodon alstoni as the type of a new genus Sigmoniys, ' arranged the 

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

 Eitneomys and Sigmoniys, which really have little in common. Later a 

 somewhat detailed comparison of Reithrodon and Enneoniys was given by 

 the present writer.* 



The genus Reithrodon 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. 



