64 MOSQUITOES OF NORTH A^IERICA 



joint of 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 seise 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 (Limalus, Lesiicocampa) 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 A'edes, 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 Aedes 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 Aedes and 

 Psorophora. In Psorophora, irrespective of the claw structure of the female, 

 the male has the large claw of the front and middle legs anned 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 



