G6 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
westward extension, suffer most. It is from this direction instead of 
fro!:i Africa that the hordes come which visit Italy and occasionally 
penetrate to Sicily. 
We may remark here that some of Wallace's boundary lines in this 
region appear to have been somewhat arbitrarily drawn, and in one case 
he appears to have been guided too much by the distribution of a single 
class of animals. If his line between 1 and 3, instead of following the 
Ural Range as it does on his map, had been traced along the valley of 
the Irtish, which he gives as the more correct eastern boundary of the 
European subregion, it would then correspond almost exactly with the 
eastern boundary of the pasture area described. 
While there are some strong reasons for uniting the northern and 
southern shores of the Mediterranean into one faunal district, there are 
equally good reasons for considering the two parts as representing two 
faunal areas, less distinct, it is true, than his subregions, but not so 
homogeneous as the parts of most of the other subregions. In fact, it 
is still a matter of doubt whether it would not have been better to con- 
sider these two parts as separate subregions. If this be done, we will 
then find the locust distribution corresponding almost exactly with the 
faunal subregions, or that their permanent distribution is limited by the 
boundaries of their respective faunal areas. The European subregion, 
if extended as indicated, and as suggested by Wallace in his text, will 
embrace what we are inclined to think is really the home of P. migra- 
torius. This is the great pasture region, and its locust is CEdipodaean. 
The Mediterranean district, as given by Wallace, is the region of mount- 
ains and deserts; the northern section, which is elevated and broken, has 
its peculiar locust, the Caloptenm italicus; the southern, or desert por- 
tion, has its own migratory species, Acridium peregrinum ; the two be- 
longing to the Acridian group of the family Acrididce. 
There is a fact which presents itself at this point that, although not 
directly necessary to this discussion, is worthy of notice, and may assist 
in solving the problem of locust-distribution in the Eastern Continent. 
Considering the Mediterranean subregion of Wallace as two sections, 
Southwestern Asia, or the region bounded by the Caspian, Black, and 
Mediterranean Seas and Persian Gulf, forms the point of union between 
the three locust districts, where we may naturally expect a commin- 
gling of the three species in their migratory movements. That such is 
the fact those who have attempted to trace the areas of distribution of 
the two great oriental species know too well. 
Here, in fact, is the meeting ground of the three true locusts of the 
Eastern Continent ; the area of the P. migratorius pressing into it on 
the north; that of A. peregrin inn on the south and southwest; while 
that of C. italicus is thrust like a wedge between the two. 
As an evidence of the commingling on this debatable ground of 
Western Asia, we have only to call attention to the statements of some 
of the authorities already quoted. 
