ALLEN : mammalia: MURID.C 47 



Only two species, both apparently belonging to the typical section of 

 the genus, are thus far known from Patagonia, where they are restricted 

 to its extreme southern part. 



Oryzomys magellanicus (Bennett). 



(Plates IX, Fig. 2, Skull; X, Figs. 4 and 5, Teeth.) 



Mhs magellanicus Bennett, P. Z. S., 1835, 191, Port Famine, Straits of 



Magellan. — Waterhouse, Zool. Voyage Beagle, Mamm., 1839, 47, 



pi. xiv, animal, pi. xxiv, fig. 6, molar teeth. — Milne-Edwards, Miss. 



Scient. du Cap Horn, VI, Zool., Mamm., 1890, 20, Orange Bay. 



Hesperoniys {Caloniys) magellanicus Burmeister, Descr. phys. Rep. Argent., 



Ill, 1879, 226 (ex Bennett and Waterhouse). 

 \Akocion\ magellanicus Trouessart, Cat. Mamm., ii, 1897, 53^' ^^ Bennett 



and Waterhouse. 

 f Hesperoniys [Oryzomys) longicaudatus Milne-Edwards, Miss. Scient. du 

 Cap Horn, VI, Zool., Mamm., 1890, 27, pi. iv, fig. i, animal.^ 

 Adult (February). — Above yellowish brown, varied with black-tipped 

 hairs, brighter on the top of the head, and middle and posterior part of 

 the back, and paler on the sides ; ventral surface buffy white, varying in 

 different specimens from nearly clear white to strong buff; front of head 

 yellowish gray strongly varied with black ; ears of medium size, dusky, 

 very thinly haired ; upper surface of feet flesh-color ; tail very long, dusky 

 brown, a little darker above than below, and very thinly covered with 

 short, bristly hairs, not concealing the annulations. 



Vonng, one fourth to half grown, in soft woolly pelage, are duller and 

 less suffused with fulvous. 



Measurements. — Six adult males: Total length, 216 mm. (202-225); 

 tail vertebras, 120 (i 14-125) ; hind foot, 29.3 (28-30). Adult male skull : 

 Total length, 26; basal length, 21 ; greatest breadth of brain case, 12 ; 

 interorbital breadth, 3.6; length of nasals, 9.5; palatal length, 19; dia- 

 stema, 6 ; palatal foramina, 5.5 ; upper molar series, 4. 



Represented by 17 specimens, of which 10 are adult and 7 young. 

 They were all, except one, collected by Mr. Peterson in the Cordilleras 

 at the head of the Rio Chico, four (all immature) being marked as from 



' Mr. Oldfield Thomas, in reply to my inquiry respecting the inclusion of this species by Milne- 

 Edwards, kindly informs me that this was probably an error, and that " the specimens were really 

 Oryzomys magellanicus." 



