246 REPORTS ON INVESTIGATIONS AND PROJECTS. 



ants, and some new data have been gained in this way. The recipient of 

 the former grants has been engaged, with the assistance of Dr. H. G. Dyar 

 and Mr. Frederick Knab, in systematic work upon the material brought 

 together by the operation of the grants. Very many new illustrations have 

 been made, and it is hoped to complete the monograph early in 1907. 



Mark, E. L., Harvard University, Cambridge, Massachusetts. Grant No. 346. 

 Significance of the fact that in mice tzvo forms of eggs ai'e produced, and its 

 bearing, if any, on heredity. $300. 



Report. — Dr. Mark and Mr. J. A. Long are conducting these investigations 

 in cooperation with the director of the Department of Experimental Evolu- 

 tion. They report that work is advancing satisfactorily and a considerable 

 number of microscopic slides of great value have been prepared. A part 

 only of these have been studied in detail, but careful drawings of some of 

 the more important sections have been made. 



Morse, Albert P., Wellesley, Massachusetts. Grant No. 284. Research on 

 North American Aoidiidce, with especial reference to biology, distribution, 

 and variation. (For previous report see Year Book No. 4, p. 283.) 



$1,000. 



Abstract of Report. — During the latter part of the trip of reconnoissance of 

 the States of the lower Mississippi Valley, made in the summer of 1905 for 

 the purpose of securing data on the biology and distribution of the locust 

 fauna of that section of the country, observation was directed particularly 

 to the transition area between the humid and arid sections, and to the status 

 of brachypterous species in the treeless districts visited. Based upon the 

 data secured upon this trip, it would appear that as a whole the biota of the 

 treeless plains and prairies is characterized by an Acridian fauna richer in 

 number of species than that of the East, and that these are of geophilous 

 and campestrian character, in consonance with the climate and the habitats 

 represented. While differing much in general facies from that of the 

 Eastern States of the same latitude in these particulars, the transition is 

 gradual rather than abrupt (agreeing with the physical conditions), the 

 border-land being peopled with numerous genera and species of very wide 

 distribution, sometimes transcontinental, sometimes restricted to the district 

 between the Mississippi River and the Rocky Mountains, but occurring both 

 in the humid and arid sections of this region. 



Brachypterous species are much less numerous proportionally in treeless 

 arid districts than in humid forested regions, East or West. When present 

 they inhabit shrubby or herbaceous thickets. It is a noteworthy fact that 

 (excluding the aberrant group Tettiginse) every flightless species of locust 

 known from the eastern half of the continent is phytophilous, as contrasted 

 with geophilous, in habits. 



