NO. 2333. MAMMALIA COLLECTED IN PERU BY HELLER— THOMAS. 237 



Zygomatic plate broad, projected forward, its front edge vertical. 

 Palatal foramina widely open. Bullae of medium size. 



Dimensions of the type.— H&ad and body, 110 mm.; tail, 80; hind- 

 foot, 22.5; ear, 16. Skull— greatest length, 28; condylo-incisive 

 length, 26.2 ; zygomatic breadth, 14.3 ; nasals, 10.4 by 3.8 ; interorbital 

 breadth, 5 ; palatilar length, 12.2 ; palatal foramina, 6.6 ; upper molax 

 series, 4.9. 



Type.— Old male from Huadquina, TT.S.N.M. No. 194663. Origi- 

 nal No. 835. Collected October 28, 1915. 



Eighteen specimens, as follows: 



Idma, 6,000 feet, 6 (Nos. 194656-8, 195077, 195079-80). 



Huadquina, 5,000 feet, 7 (Nos. 194661-3, 194694, 195087-9). 



Paltaybamba, 5,000 feet, 1 (No. 195068). 



Santa Ana, 4 (Nos. 195081-4). 



This Akodon differs from its nearest ally, A. mollis, by its stouter 

 build and smokier color, without tinge of buffy. The animal is of 

 interest in connection with its strong external resemblance to the 

 species here called Microxus torques. The two are found, respec- 

 tively, at low (5,000-6,000 feet) and high (8,000-14,000 feet) alti- 

 tudes and apparently represent the lowland and highland forms of 

 northern Peru, distinguished by Osgood merely as subspecies of 

 A. mollis— a closeness of relationship which, as explained below, 

 under Microxus torques, I am not prepared to accept. 



44. AKODON BOUVIENSIS (Meyen). 



Eightv-six specimens, as follows: 



Huaracondo, 40 (Nos. 194664^5, 194669, 194671-2, 194731-2, 

 194734-5. 194739-40, 194998-195024, 195101-2). 



Chospyoc, 10,000 feet, 3 (Nos. 194673, 194742-3). 



Machu Picchu, 14,000 feet, 1 (No. 194744). 



Ollantaytambo, 13.000 feet, 22 (Nos. 19467^5, 194746-59, 194951-3, 

 194959-61). 



Ocobamba Valley, 9,100 feet, 9 (Nos. 194760-4, 194962-5). 



Paltabamba, 5,000 feet, 3 (Nos. 194642, 194644-5). 



Lucma, 9,000 feet, 1 (No. 194646). 



Chiarapata, 11,200 feet, 2 (Nos. 194697-8). 



Santa Ana, 3,500 feet, 2 (Nos. 194659-60). 



La Eaya Pass, 14,000 feet, 3 (Nos. 194695-6, no skulls, identification 

 not positive, 195090 in alcohol). 



The common small grass mouse of eastern Peru and Bolivia. 



[AKODON (CHALCOMYS) AEROSUS BALIOLUS Osgood]. 



[One specimen in the British Museum from Callanga, Cuzco. O. 

 Garlepp. No. 98.11.6.2.] 



I record this under the name given by Mr. Osgood to the Inambari 

 form of A. aerosus, but do not express any opinion as to its degree of 

 difference from true aerosus. 



