A REVISION OF THE GENUS LOCUSTA, L. 



139 



Though it would be interesting and useful to give individual dimensions of all 

 the specimens measured, I refrain from doing so in order not to encumber this paper 

 with many pages of figures. I will give, therefore, only a general table of the chief 

 results obtained, which will be enough for our conclusions (see Table I). 



Table L 

 Showing Dimensions of different Phases of L. migratoria, L. 



* Relation of the shoi'.lder width to the length of pronotum. 

 t Relation of the length of hind femur to that of the elytron. 



When studying the first two lines of the table we see that individual figures for 

 specimens of both forms are highly variable. Owing to this variability there is no 

 interval between a row of figures for danica and that for migratoria. which partly 

 overlap each other. This accounts for the fact that a curve representing the 

 variabilit}' of the pronotal proportion (fig. 2) in both forms together has only one 

 maximum ; it seems to indicate that, so far as the shape of the pronotum is concerned, 

 there is no possibihty of regarding migratoria and danica as different species, or 

 even as two distinct forms of the same species. The curve of variability of the 

 femoral proportion (fig. 3), on the contrary, has two separate maxima, as if the 

 material studied could be divided into two distinct groups, be these species or units 

 of lower taxonomic value. 



As for the average figures for both forms, they are also quite distinct and even 

 not too near each other ; the maxima and minima are also more or less characteristic 

 for each form. It may be noted that danica is more variable than migratoria. the 

 extent of variation in it amounting to 35 per cent, of the average figure in the case 

 of the pronotal proportion and about 38 per cent, for the femoral ; while the corre- 

 sponding variations in migratoria are only about 29 and 26 per cent, respectively. 

 The next interesting point is that specimens of danica from the Palaearctic region 

 are far more variable than those of extra-Palaearctic origin. 



(3442) , ^ 



