CHROMOSOME STUDIES 273 



this genus the same minor variation (such as Nabours has worked 

 out), but considerably modified from ,the condition found in 

 the three more closely related genera. This seems to be the 

 case in regard to at least the 'punctofemorata/ 'leuconotus' 

 and 'lineatus' characters. Such characters are present in Tet- 

 tigidea, but apparently widely different from what they are 

 in any of the other three genera. 



It appears to me that in the varying behavior of the chromo- 

 somes among the genera of this subfamily we have a splendid- 

 opportunity, by repeating on other species and genera the work 

 of Nabours, to find out something of the workings of the chromo- 

 somes in respect at least to minor, non-vital variations, such as 

 these seem to be. 



The chromosome studies which I here present were begun 

 at the University of Kansas in 1908 under the direction of 

 Prof. C. E. McClung. A part of my material was collected 

 at Lawrence, Kans., and also in the course of zoological collect- 

 ing trips on which he was kind enough to send me to Arizona, 

 Texas, and Puget Sound, Washington. The studies were con- 

 tinued at Harvard University from October, 1909, to June, 1912 

 under the direction of Prof. E. L. Mark. I am indebted to both 

 of these men, to Professor McClung for starting me upon the 

 work and for his kindly interest afterward, and to Professor 

 Mark for his helpful criticism and guidance and for the encour- 

 agement he gave me during the time when the bulk of the work 

 was being done. 



April 28, 1915. 



