ALLEN: mammalia: murid^. yi 



genus, Chelemys, with A. megalonyx (Waterhouse) as the type, to include 

 A. macronyx and A. vestitus Thomas. Another natural group, of at least 

 subgeneric value, consists of A. caligiuosus (Tomes), A. iinc/ii All. & 

 Chapm., A. imzu and A. venezmlensis Allen, A. tegitina (Alston), etc. ; 

 A. pulcherrimns, with its large ears and striking color-pattern, is possibly 

 also separable from such forms as A. canesceus, A. xantlwrhimts and their 

 allies. 



For the purpose of convenient comparison, figures are given of the 

 skull and dentition of several of the leading types of Akodoii on plates 

 XI and XII of this work, namely, A. xantliovhiniis, A. canesceus, A. 

 caliginosus, A. pulcherrimus, A. sitffusus, and A. vesfitus. 



The genus Akodon has a wide geographical distribution, being repre- 

 sented from Costa Rica southward to the Straits of Magellan, and is 

 especially prolific in specific and subspecific forms throughout the Andean 

 region. It is represented in the collections made in Southern Patagonia 

 by the Princeton University Patagonia Expeditions by five species, four 

 of which — A. xauthorhiuus, A. canesceus, A. sitffusus 2inA A. vestitits — 

 are each represented by large series of specimens, while the fifth, A. mi- 

 c/icslseut, by a single excellent skin, without, however, the skull. 



Besides these Philippi described in 1900 a Mus pachycephaliis, which 

 appears to be an Akodou, with the statement "Habitat in Freto Magel- 

 lanico"; but the description is not satisfactory, and the species is not 

 here formally included. 



Akodon xanthorhinus (Waterhouse). 

 Mus xauthorliiuus Waterhouse, P. Z. S., Nov. 21, 1837, i?; Zool. 

 Voyage Beagle, Mamm., 1839, 53, pi. xvii, fig. i (animal). "Hardy 

 Peninsula, Tierra del Fuego (February)." 

 Hesperoniys ( Habfothrix) xanthorhinus Thomas, P. Z. S., 1881, 5, part; 

 the Sandy Point specimen only. 

 Adult (January). — Above dull yellowish brown, closely resembling 

 July specimens of ^. canesceus; underparts whitish gray; nose, feet, and 

 tail also similar to these parts in canesceus — pale rusty fulvous. 



Measurements.— AdnXi male, Punta Arenas, Chili, Jan. i, 1898: Total 

 length, 151 mm. ; tail vertebrae, 62 ; hind foot, 20. Skull (4 adults), total 

 length, 25 (24.6-25.3); greatest width of brain case, 11.35 (ii-il6). 

 This species is represented by 10 specimens collected by Mr. Colburn, 



