64 MOSQUITOES OF NORTH AMERICA 
jotniof the front and middle legs, or of the front legs alone, differs considerably 
from the others. In these cases it is considerably longer than the fourth joint 
and is more or less deeply concave along nearly its entire under side. It is 
broadest at the base which is often produced beneath into a tooth. Sometimes 
there is a spinose process near the middle of the concavity. The fifth joint 
usually bears many sets towards the apex, particularly when modified as just 
described. In the case of such modification it also generally bears a series of 
spines basally beneath. When the fifth tarsal of both the front and middle legs 
is modified as just described the development is greater on the front legs, in- 
deed, forms occur in which the concavity is but slightly indicated on the middle 
legs. 
“The claws are inserted at the apex of the last tarsal joint. There are nearly 
always two claws but in a few cases (Limatus, Lesticocampa) there is but a 
single claw on the hind legs. They are curved and taper to a point. When with- 
out teeth the claws are said to be simple. When the two claws of the same foot 
are of the same length they are said to be equal. In the females each pair of 
claws is equal or nearly so, but they differ much in size in the different genera. 
The claws of the hind leg are often much smaller than the others. In the female 
the claws are most often simple. In the females of many species of Psorophora 
and Aédes, and of some Stegoconops, at least the claws of the front and middle 
legs bear a distinct tooth before the middle. In certain species of these genera 
the hind claws also are toothed. This, however, appears to be a variable char- 
acter in some species. In Aédes sylvestris the hind claws of the female may be 
simple or toothed. Indeed we have a specimen of this species in which three 
of the claws of the hind legs are simple while the remaining one is toothed; in 
another specimen three claws of the hind legs are toothed and one is simple. 
In the males the claws of some of the legs are usually modified in a striking 
manner. In the Culicini it is generally the claws of the front legs that show 
sexual peculiarities, and often also the claws of the middle legs. There is often 
considerable diversity in this respect among the members of a single genus. In 
Culex pipiens, and in many other species of Culex, the inner claw of the front 
and middle legs is much larger than its mate and bears a long tooth outwardly 
near the middle; the other claw bears a tooth on the opposite side near the base. 
The position of the teeth on the claws differs in some of the species; the tooth on 
the large claw may be nearer the base and the tooth on the small claw moved 
farther out. In certain species the tooth of the small claw is much reduced and 
in others it is absent. In Culex latisquama only the large claw of the front legs 
is toothed ; the claws of the middle legs are simple, but unequal in shape and 
length. It may be remarked that in correlation with these simple claws of this 
species are the longer fourth tarsal joints of the front and middle legs. There is 
great diversity in the claws of the males of the different species of Aédes and 
Psorophora. In Psorophora, irrespective of the claw structure of the female, 
the male has the large claw of the front and middle legs armed with two teeth, 
one near the middle, the other basal, while the smaller claw bears a single tooth. 
In those forms of this genus in which the claws of the female are toothed the 
