DISTRIBUTION OF BIRD-LIFE IN PERU. 645 



Major Stanley S. Flower, O.B.E., P.Z.S., exhibited examples 

 of three species of Egyptian Jerboas — Jacidus jaculus, Jactdus, 

 orientalis, and Scarturas ietradacii/hts, the latter being the first 

 living specimens ever brought to England ; and made remarks 

 upon the distribution of the thi-ee species in North Africa. 



June 7th, 1921. 



Prof. J. P. Hill, F.R.S., Vice-President, 

 in the Chair. 



Major Stanley S. Flower, O.B.E., F.Z.S., exhibited, and made 

 remarks upon, some living specimens of Testudo leithii and ai"! 

 example of Testudo ihera. 



Dr. P. Chalmers Mitchell, C.B.E., F.R.S., exhibited, and 

 made remarks upon, a, photograph of the Death-mask of a young 

 Gorilla, presented to the Society hj Prof. Howard Macgregor, of 

 Columbia University, New York. 



Dr. Frank M. Chapman gave an account of the distribution of 

 Bird-life in the Urubamba Valley of Peru, and of his expedition 

 down the Urubamba river from its sources in the Puna zone, at 

 an elevation of 14,200 feet, to the Tropical zone at 3500 feet. 

 He reviewed the existing climatic conditions in Peru, and com- 

 mented on the faunal characteristics of the Puna, Temperate, 

 Subtropical, and Tropical zones encountered in the descent. A 

 comparison of the Avifauna of the forests of the humid Temperate 

 zone (alt. 10,000-12,500 ft.) with that of the adjoining treeless, 

 grass-gi'own plains and slopes of the Puna zone, showed that that 

 of the first-named area has evidently been derived from the 

 tropical forests at the eastern base of the Andes ; that of the 

 latter from the South Temperate zone plains of Argentina and 

 Patagonia. The environmental change experienced in passing 

 from the hot, tropical forests, at the foot of the mountains, to 

 the cold temperate forests near their summits, is much greater 

 than that existing between the plains of Patagonia and' those of 

 the Interandine tableland. This is obviously rsflected in the 

 degree of differentiation exhibited by the birds inhabiting these 

 elevated forests and plains. Thus 55 per cent, of the genera of 

 birds inhabiting the Temperate zone forests are endemic, while 



