6 MOSQUITOES OF NOETH AMEEICA 



doubt whether the characters used to separate the larvre specifically are actually 

 reliable, but we give them for what they are worth. 



The species of Mansonia are, for the most part, easily separable on characters 

 of coloration. Of the larvae, we know only two species as fully grown larvae, so 

 that we have been unable to make a full synoptic table of them. 



The species of Psorophora divide on the presence or absence of smooth nude 

 areas on the mesonotum, on the presence or absence of a tooth on the tarsal 

 claws of the female, on the characters of the vestiture of the legs and the colora- 

 tion of the legs and body. 



In Aedcs we use as the primary character the presence or absence of a tooth 

 on the tarsal claws in the female, followed by characters of coloration that 

 require no special explanation. The species of Aedes, as a whole, are less subject 

 to variation than those of Culex. There are, however, certain species which vary 

 extremely in the scale-ornamentation of the mesonotum and abdomen. In 

 several cases the adults are practically identical and no certainty of separation 

 can be had without a knowledge of the male genitalia or early stages. Such 

 species we have separated by geographical distribution, where possible. Specific 

 variation is most marked in the ornamentation of the mesonotum, but even here 

 is scarcely great enough to cause confusion. We anticipate that our table will 

 be available for material in good condition. 



The species of Hmmagogus, though few in number, separate into two groups 

 differing in venation, armature of the claws of the female, and length of the 

 palpi of the male. Generic names have been proposed for these divisions, but 

 seem unnecessary. The species further separate on the amount of silvery mark- 

 ing on the abdomen, which is somewhat variable and more abundant in the 

 males than in the females, so that a little care must be exercised in considering 

 this point. In the species with short male palpi minute bristles occur pos- 

 teriorly on the postnotum ; but these are often absent, so that they can not be 

 used even for specific diagnosis. 



The species of Megarhinus are separable by the presence or absence of red anal 

 tufts and the coloration of the mesonotum and legs. The latter is subject to 

 sexual dimorphism, so that a separate table for the determination of the two 

 sexes has been found useful. The species are well fixed and the larvge nearly 

 allied, but separable on good characters. 



The Anopheles separate on the coloration of the wings, legs, and palpi. Some 

 of the species are closely allied to each other and the markings on the wings 

 present some variation, but not so as to call for special comment. The larvae 

 have proved for the most part practically inseparable, except on minute char- 

 acters; the dentition of the lateral comb has proved to be variable. 



Besides the tables for adults, we also give tables by the male genitalia and by 

 larvae. 



The male genitalia do not separate the tribes Sabethini and Culicini. In the 

 Sabethini, the genera separate broadly on the modification of the clasp filament, 

 which is simple in the more generalized forms, but the characters do not define 

 the genera separately. In Wyeotnyia (including Limatus, Sahethes, and Sahe- 



