150 B. p. UVAROV. 



After studying the specimens, I can only confirm Plotnikov's statement that while 

 the parents are all very typical danica, save that not all of them have the hind tibiae 

 red (which character is not quite constant in that form), their direct offspring are 

 on the contrary all well-defined migratoria, though a few of them have the tibiae 

 red, as is sometimes the case in this form. One of the parents and one of the 

 off-spring are figured above (fig. 1, A, B, C, & D). 



Another experiment is described by V. Plotnikov, as follows : — 



" In 1914 I bred from egg-masses sent from Amu-Darya district* P. migratorius, 

 and from egg-masses deposited by these insects I bred in the spring of 1915 again 

 migratorius. On the 19th June I found in the soil of the breeding cage, where these 

 individuals (now mature) used to live, five egg-masses, which I transplanted carefully 

 into the soil of another cage ; there, on the 6th August, i.e., more than 48 days 

 after the oviposition, a single larva hatched, a female of dark grey coloration ; the 

 rest of eggs in the egg-masses remained with an half-developed (hibernating) 

 embryo. When in its second stage, this larva acquired a green coloration, which it 

 retained till the fifth (final) stage. The profile of its pronotal keel was convex. . . . 

 The adult insect retained the convex keel of the pronotum ; its body was green, 

 the elytra light brown, and its hind tibiae turned red." 



This specimen is before me now, and I can only confirm V. Plotnikov's opinion 

 that it represents the most typical danica. As for its actual parents they possess 

 all the essential characters of migratoria very well defined, and no one could hesitate 

 to identify them with that form. Unfortunately the experiments were discontinued 

 upon Plotnikov's joining the army. 



V. Plotnikov's conclusion from his experiments is as follows : "... it is 

 impossible to separate P. migratorius and P. danicus by any characters ; characters 

 of danicus (including its capacity to produce a second generation) are expressed in 

 the latter species more strongly. It is possible to suppose that this species is now 

 in the process of splitting off from the primitive species, P. migratorius." 



My own conclusions differ somewhat from this, but I shall come to them later 

 on. All that I shall point out now is that these experiments prove finally the 

 possibility of the actual breeding of migratoria from danica and vice versa ; my 

 field observations on the same subject give evidence that it may occur not under 

 laboratory conditions only, but in nature as well. On the other hand, we must 

 not forget the numerous differences between them, especially the biological ones, 

 which prevent us from regarding danica as a mere synonym of migratoria. It is 

 evident that they must be regarded as two different forms of the same species without, 

 in the meantime, any more precise definition of their systematic value. 



Lociista migratorioides, Rch. & Frm. 



This insect was described from specimens from Abyssinia ; later on, Saussure 

 and other authors recorded it from many tropical localities. In its morphological 

 features it is very much hke migratoria, while its difference from danica is far more 

 marked than in the latter. From migratoria it differs only in the following 

 characters : — The pronotum (fig. 4) is still more constricted before the middle ; its 

 median keel very low, often concave in profile ; fore margin almost straight ; hind 

 margin very widely rounded ; the shoulder width almost equal to the length of the 

 pronotum, the average pronotal proportion being 0-86, while it is 0-80 in migratoria ; 

 the elytra relatively longer and the hind femora shorter, which results in the femoral 

 proportion being on the average 0-44, as against 0-46 in migratoria (see Table I, 

 lines 20 & 21). 



* A permanent breeding region of L. migratoria.— "B.V . 



