116 MR. OLDFIELD THOMAS ON [Feb. 18, 



Hah. Mountainous region south and south-east of the Titicaca- 

 Poopo basin. Potosi, 4400 metres (type) ; Oruro, 3700 m. ; 

 Livichuco, 4500 m. ; Ohallapata, 3800 m. 



Tijjje. Adult female. B. M. No. 2.2.2.2. Original number 1620. 

 Collected October 1st, 1901, by Mr. P. 0. Simons. 15 specimens 

 examined. 



Native names " Chockchuri " and " Achaco." " Fovind among 

 rocks and cactus, in caves and old Indian tombs ; nocturnal " 

 {Simons). 



I have had great pleasure in connecting with this very beautiful 

 animal the name of Mr. Simons, in recognition of the remarkable 

 collecting work he has done in the Andean chain during the last 

 three years. His collections already number over 1 600 mammals, 

 more than 3000 birds, many hundreds of reptiles and amphibians, 

 and large numbers of insects and other invertebrntes. 



Andinomys, gen. nov. [Cricetmce.) 



Form murine. Thximb with a broad nail. Tail well-haired, 

 but not pencilled. 



Skull rat-like. Muzzle long, broad, and heavy. Interorbital 

 region narrow, parallel-sided, without ridges. Palatal foramina 

 large, with very sharply defined edges. BuIIpb small. 



Incisors heavy, smooth anteriorly. Molars very large, highly 

 hypsodont, as in Chinchillula^ but their pattern more as in 

 Phyllotis, though with almost a microtine appearance in youth, 

 when they aie much more complicated than would be at all 

 easily perceived from their structui'e in adult life (see figures). 



This genus, like Chinchillula^, is a highly hypsodont and heavily 

 toothed relative of Phyllotis, itself more hypsodont than the 

 brachyodont Eligmodontia. But in Chinchillula the teeth are 

 remarkably simple, practically alike in youth and age, with 

 opposite and connected enamel-spaces, as shown in the figures 

 (Plate IX. figs. 5, 7). In Andinomys, on the other hand, the 

 spaces are more or less alternated, the pattern, especially of on^, 

 becomes less complicated with age owing to the wearing-out of 

 accessory columns, and the spaces are or gradually become isolated 

 from each other ; the lateral angles are much more acute in 

 youth, becoming comparatively blunt in old age. 



Andinomys edax, sp. n. (Plate IX. figs. 1-4, 6.) 



General appearance of a large Phyllotis or soft-haiied Oryzomys. 

 Fur long, fine and soft, but not woolly; bans of back about 19- 

 20 mm. in length. General colour above dull bufFy or fulvous 

 bufFy, lined with black ; sides cleaier, sandy bufiy ; under surface 

 not sharply defined, bufliy white, the haii-s slaty basally. Head like 

 body ; no oi-bital markings. Eais fairly large, closely haired, bi'own 



i_ Chinchillula was originally founded (Ann. Mag. N. H. (7) i. p. 280, 1898) on 

 a single immature skin, but the British Museum now possesses a series of adult 

 examples collected b}' Mr. Simons at Cayllonia, Peru. 



