158 



B. P. UVAROV. 



shorter than in the soHtary phase. The femoral proportion {i.e., the length of hind 

 femora expressed as a percentage of the length of the elytra) in the swarming phase 

 averages 0-44, with a maximum of 0-47, and a minimum of 0-41 ; the average 

 proportion for the solitary phase is 0-46, with 0-50 maximum and 0-41 minimum. 



While the elytra of migratoria and danica do not differ except in the relative 

 length, there exists a well-marked difference in the shape and venation of the elytra 

 in the two phases of pardalina. Those of the swarming phase (fig. 5, C) are broader, 

 with the fore margin more convex and the apex obliquely rounded, while the solitary 

 phase (fig. 5, F) has the elytra narrower, with the margins almost straight and parallel 

 and the apex obliquely truncate. The most striking difference, however, is in the 

 venation : the discoidal field in the swarming phase is much broader, and its false 

 vein distinctly curved and much thicker than in the solitary phase, in which this 

 field is rather narrow, parallel-sided, and with the false vein only slightly thickened 

 and almost, or even quite, straight. Naturally all these characters are subject to 

 variation, and forms in all respects intermediate occur. 



CdT 



> 



Fie 



5. Locustana pardalina, Walk. : A, B, C, phase pardalina ; D, E, F, phase solitaria, Uvar., iiov.; 

 C and F, natural size, remainder x 3. 



The difference in the absolute dimensions between the two phases of pardalina, 

 noted by Mr. Faure, is a phenomenon not observed in migratoria, but in the South 

 African species it is well marked, the average length of the body of the swarming 

 phase being 41 mm., while in the sohtary phase it is only 34 mm., and occasional 

 specimens occur even as small as but 24 mm. The individual variability in size 

 is in the solitary phase very extensive, but the swarming phase is rather constant 

 in this respect ; this is also the case in the phases of migratoria. Again, sexual 

 dimorphism is as well marked in the solitary phase of pardalina as it is in danica, 

 the average length of the body being 32 mm. in the males and 36 mm. in the females, 

 while the difference in the size of dwarf males, attaining about 22-24 mm., and the 

 largest females with a length of nearly 45 mm. is very striking. The males of the 

 swarming phase are scarcely smaller than the females, which agrees with the relative 

 size of the sexes in typical migratoria or migratorioides. 



