2 Trans. Acad, Sci. of St. Louis 
they ceased to be occupied. Seven occupied nests were found 
in Ithaca, N. Y., and their history recorded as at Evanston. 
Trips were made on two hundred and twenty-three days to 
observe the Larks and on many of these days the breeding 
grounds were visited twice. These visits were distributed by 
months, as follows: Six in January, fourteen in February, 
twenty-five in March, forty-six in April, forty-four in May, 
fifty-two in June, twenty-one in July, one in August, two 
in September, three in October, five in November, four in 
December. 
Though efforts were made to cover all activities of the Prairie 
Horned Lark, yet as data accumulated there accumulated also 
desiderata almost as large. So that, as the problem is now 
brought to an arbitrary close, the things yet to be learned seem 
more momentous by far than the few things learned—so inade- 
quate are two years of work, no matter how intensive. 
Acknowledgments,—Daily visits to an area five miles from 
the Campus of Northwestern University where the writer was 
teaching would not have been possible except for the hearty 
co-operation of the members and assistants of the Department 
of Zoology there. Sincere thanks are extended here also to 
r. P. A. Taverner of the National Museum of Canada, to 
Mr. H. F. Lewis and Mr. R. W. Tufts, Federal Migratory Bird 
Officers of Quebee and the Maritime Provinces respectively, for 
information relative to 0. a. alpestris and O. a. praticola of 
various regions of eastern Canada. To Clarice Pickwell much 
eredit is due for assistance throughout the entire period of 
preparation of the manuscript. Lastly the writer is greatly 
indebted to Dr. A. A. Allen of the Laboratory of Ornithology 
of Cornell University for the opportunity he gave that the work 
might be brought to a successful conclusion and for his advice 
on many phases of the problem. 
