448 CARNEGIE INSTITUTION OF WASHINGTON. 



the Museum of History, Science and Art of Los Angeles, and the U. S. 

 National Museum, together with the aid of many other agencies con- 

 tributing to success of the work. 



The University of California has graciously made available such 

 quarters as are needed for use in work upon the collections of the Mu- 

 seum of Palaeontology, and every needed assistance has been given 

 by the University and by the staffs of several departments. 



The Museum of History, Science and Art of Los Angeles has been 

 most courteous in the offer of its splendid collections from the asphalt 

 pits of Rancho La Brea. The Museum has not only furnished mate- 

 rial but has cooperated through the use of its staff in every possible 

 way to advance study of the collections to a point at which publica- 

 tion of the results may be possible. 



The U. S. National Museum has offered quarters for work and has 

 given every possible facility for the study of materials contributing 

 in any way to an understanding of the problems involved. 



The active operations in research have been based in a large measure 

 upon collections assembled during the past twenty-five years and upon 

 which the regular course of study was interrupted during the period 

 of the Great War. Furtherance of the investigations under way has 

 also required field work which has been carried on in the following 

 regions: (1) asphalt pits of Rancho La Brea, California; (2) newly dis- 

 covered Pleistocene asphalt deposits in the southwestern part of the 

 Great Valley of California; (3) late Tertiary mammal-bearing deposits 

 near Alturas, northeastern California; (4) many localities in marine 

 Tertiary formations of the Coast Range region of California; (5) over 

 a wide range of localities at which formations are found containing 

 fossil plants in a region extending from Rancho La Brea in southern 

 Calif ornia, through northern Calif ornia, w^estern Oregon, and especially 

 in the John Day region of eastern Oregon and the Snake River region 

 of Idaho. 



The field work at Rancho La Brea has involved only minor studies 

 connected with the construction of a monograph covering description 

 of the mode of occurrence of the remarkable deposit of mammal and 

 bird remains found in the ancient asphalt beds at this locality. The 

 first careful study of the fossil plants of Rancho La Brea was under- 

 taken during the past year by Mr. Chaney, with the idea of securing 

 as full information as possible regarding the flora of this region. 



The investigations in the asphalt beds near McKittrick, on the south- 

 western side of the Great Valley of California, have included excavation 

 work on a series of deposits containing a mammalian fauna from the 

 Pleistocene or the period immediately preceding the present. These 

 deposits have been known for many years and have furnished small 

 quantities of bones from time to time. Not until recently has the 

 deposit shown promise of furnishing large collections. The field work 

 this year has brought forth abundant material with preservation 



