13 



hibited maps depicting the extent of these zones, and described 

 how the highland fauna had been left as it were on islands by a 

 retreating tide of northern forms and how the life of the Pacific 

 coast had been since acquired from the north, and that of the 

 interior valleys from the south around the northeastern end of 

 the ranges. 



Mr. C. William Beebe gave the second paper, entitled, ''A 

 Tetrapteryx Stage in the Evolution of Birds."* He had dis- 

 covered a double row of feathers, apparently analogous to 

 wing-quills and their coverts, across the membrane of the hind 

 limb of a squab White-winged Dove (Melopelia asiatica) . This 

 led to the conception of his theory that far back in the great 

 gap between Archseopteryx and its reptilian ancestors, the 

 pro-aves had begun gliding flight from an eminence by means 

 of the imperfect development of all four limbs as wings. Sim- 

 ilar feathers in the very young of some other birds, particu- 

 larly Jacanas (Jacana), and the fact that in bats and in all 

 living creatures with gliding flight the hind limbs function, 

 strengthened the theory. Considerable discussion, led by 

 Dr. Gregory, followed. 



Dr. Mathews read extracts from Prof, Thomas Barbour's 

 review of his '' Climate and Evolution." 



December 28 , 1915. — The President in the chair. Thirteen 

 members (Dr. Dwight and Messrs. C. G. Abbott, Chapin, 

 Cleaves, Harper, Hix, F. W. Hyde, Ladd, Lang, Marks, 

 Rogers, Saunders and Weber) and 8 visitors present. 



Mr. Rogers proposed for Resident Membership Mr. Clarence 

 R. Halter, a Columbia University student working also in the 

 Department of Herpetology of the American Museum. The 

 name was referred to the Committee on Membership. 



Mr. Rogers exhibited various recent accessions to the Mu- 

 seum's collection of local birds, the more interesting being: 



Ruff {Machetes pugnax) . a male in immature plumage, taken 

 September 27, 1914, at Freeport, L. I. 



American Egret (Herodias egretta), a male just completing 

 its post-nuptial molt, picked up at Ossining, N. Y., July 31, 

 1915. 



* See this title in Zoologica, II, 35-52. 



