REPORT OF NATIONAL, MUSEUM, 1921. 95 



continued his descriptive work on American Pleistocene faunas ; and 

 many other specialists, among whom may be mentioned Ferdinand 

 Canu, Versailles, France; Dr. M. A. Howe, New York Botanical 

 Gardens; Dr. J. A. Cushman, Boston Society of Natural History; 

 Prof. T. D. A. Cockrell, Boulder, Colo.; and Dr. R. T. Jackson, 

 Peterboro, N. H,, have collaborated by their studies. 



Mr. A. Rodolfo Martinez, of the Geological Institute of Mexico, 

 has been working in the laboratory studying methods of mineralog- 

 ical and petrological research. 



Distributions. — Exchanges predominated in the distributions made 

 during the year. These were comprised in 41 shipments with an 

 aggregate of 10,250 specimens and 374 pounds of material in bulk. 

 Eleven specially prepared lots, comprising 447 specimens, were sent 

 out as gifts, and 612 individual specimens, with the addition of 150 

 l^ounds of magnetite, were transmitted in 20 shipments to special 

 students and institutions for investigation or experimental work. 



In addition, 23 sets of ores and minerals, 3 sets illustrating rock 

 weathering and soil formation, and 3 sets of invertebrate fossils, ag- 

 gregating 2,156 specimens, were distributed to schools. 



Total number of specimens in the de'pojrtment. — It is impossible 

 to give with even approximate accuracy the number of specimens in 

 a collection of this nature. It is estimated, however, that the collec- 

 tions of the several divisions yield a total of not less than 1,500,000 

 specimens. No statement as to the number of duplicates included 

 can possibly be made. 

 71305°— 21 7 



