RECORDS OF MEETINGS OF 1907 351 



by a series of beautiful lantern slides and of moving pictures, in a novel 

 representation of volcanic outbursts and rising vapors. On motion by Dr. 

 Hovey, a hearty vote of thanks was given by the Section to Mr. Perret for 

 his unique exhibit. 



The Section then adjourned. 



Alexis A. Julien, 



Secretary. 



SECTION OF BIOLOGY. 



November 11, 1907. 



Section met at 8:15 P. M., Vice-President Crampton presiding. 



The minutes of the last meeting of the Section were read and approved. 



After a short business meeting, at which Frank M. Chapman was nomi- 

 nated Vice-President of the Academy and Roy W. Miner was elected Secre- 

 tary of the Section, for 1908, the following papers were read: 



Henry F. Osbom, A Paleontological Trip to Northwestern Ne- 

 braska. 



Frank M. Chapman, The Ptarmigan — Living and Dead. 



Jonathan Dwight, Jr. The Distribution of the Juncos, or Snow Birds, 



on the North American Continent. 



Summary of Papers. 



Professor Osbom reported upon two excursions, during the seasons of 

 1906 and 1907, into the Lower Miocene beds of northwestern Nebraska, 

 variously knov^m as Arikaree, Harrison and Rosebud. 



The recognition of these beds as containing fauna transitional between 

 the Oligocene and Lower Miocene is due to the successive explorations of 

 Hatcher, Barbour, Peterson, Matthew and Thomson. The lower division 

 (Lower Harrison, Lower Rosebud) is more directly comparable with the 

 true Upper Oligocene of France. The upper division (Upper Harrison, 

 Upper Rosebud) may represent the close of the Oligocene or the beginning 

 of the Miocene, and is sharply defined from the lower division by the absence 

 of certain mammals and the presence of others. The formation as a whole 

 is a very grand one, extending continuously over 200 miles east and west; 

 varying in thickness from 1,200 feet in the west to 800 feet farther east. It 



