324 



ANIMAL AGGREGATIONS 



file. Loaista danica has the pronotum relatively longer and more 

 compressed laterally ; the midconstriction is less pronounced ; the me- 

 dian keel is higher and is convex in outline. The elytra of the former 

 are relatively longer and the hind femora relatively shorter than in 



Fa MORAL Proport/oaj 



Fig. 34. — Graph showing the range of variation of the femoral proportion in 35S 

 specimens of Locusta migratoria L. (After Uvarov 1928, by permission of the Imperial 

 Bureau of Entomology.) 



L. danica. These differences are summarized in numerical values 

 in Figures ;^;^ and 34. A study of Figure t,t, shows that, so far as the 

 pronotum characters are concerned, there is no evidence to indicate 

 that here are two species, or even two forms of one species, but that 

 with the femoral proportions there is a distinct difference in the 

 grasshoppers shown by the two-humped curve. The hump to the 

 right represents the L. danica type. Proportions taken for many 



