44 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



in the foothills of the Andes, on the upper Rio Chico, where, however, he 



found a much larger species ( C. robustiis) abundant, and also obtained, in 



the same region, a small series of a very much smaller species (C seri- 



ceiis). In all probability C. colbitrni ^nWS. be found to be a plains or pampa 



species, while the others occupy the alluvial river valleys in the foothills ^ 



of the Andes. 



Family MURIDy^. 



The Murine fauna of southern Patagonia is as strongly characterized by 

 the types that are absent as by those that are present. The Voles, or the 

 great subfamily Microtinae, are of course absent, as are also all the char- 

 acteristic North American genera of the Cricetin£e, as Peromyscus, Ony- 

 choniys, Neofonia, Reithrodoiitomys, and Signwdoii, although all extend 

 into tropical America, and all but Onyckoniys even reach the northern 

 border of South America. Another set of genera, as Rhipidomys, Nec- 

 tomys, HolocJiilits, and Tyloniys, which range over a large part of Central 

 and South America, do not reach even the northern border of Patagonia. 

 Of the seven prominent Patagonia genera — Eiineomys, Reithrodon, Phyl- 

 lotis, Eligmodontia, Oxyjuyctents, Oryzojuys, and Akodoii — only the last 

 two have a wide distribution to the northward, except in the Andean 

 region, where nearly all are highly developed. The single genus 

 Notioniys is thus far known only from the original specimen taken near 

 Santa Cruz. It is closely related to Eliginodoutia and certain forms of 

 Akodon (subgenus Chelyniys), types that abound over the pampean dis- 

 tricts of Argentina and Bolivia. 



Genus MUS Linnaeus. 



In America the genus Mus, a strictly Old World type, is of course rep- 

 resented only by introduced species, three or four of which have become 

 almost universally dispersed over both continents, and may all occur in 

 Patagonia, although satisfactory evidence of this is at present lacking. 



Mus RATTUS Linn. Black Rat. 



The collection contains a single specimen (a half grown female) collected 

 at Punta Arenas, December 30, 1897, by Mr. E. A. Colburn. The meas- 

 urements as recorded by the collector are: "Length, 280; tail, 150; hind 

 foot, 32." 



In coloration this specimen is very different from the black rats of the 



y 



