Carpenter et al.: Mosquitoes of Southern U. S. 



43 



length to width, the nature, number and position of the pecten teeth, and the 

 number, development and position of hair tufts. The proportion of length to 

 width is usually obtained by comparing the length of the siphon, excluding the 

 acus and the valves, with its width at the base or at its widest point. A siphon 

 is referred to as "inflated" if it is considerably wider near the middle than at 

 the base, as exhibited by Psorophora cyanescens (Fig. 72). 



The ninth or anal segment possesses several important structures. A large 

 sclerotized dorsal plate may or may not completely ring the anal segment and 

 bears a lateral hair or tuft on either side near its posterior margin. From the 

 dorso-apical angle of the anal segment arises the dorsal brush composed of the 

 upper and lower caudal hairs. The ventro-apical margin has a ventral brush 

 composed of a staggered row of hair tufts, the bases of which may be sclero- 

 tized to form what is known as the barred area or grid. The tufts arising from 

 the barred area or grid may be referred to as the cratal tujts, and those arising 

 before the grid as the precratal tufts. The anal segment bears posteriorly two 



B 



inger-like A \/ 



nrnrAcc A 'fi 



vtntrol 

 iODrc 



- popillo 



epicranial suture 



-lorvol eye 

 -imoginol eye 



--ocular sclerife 



Fig. 19. Head of Anopheles larva. A, Dorsal view of head. (I), preclypeal spine; 

 (2). inner clypeal hair; (3), outer clypeal hair; (4), postclypeal hair; (5), inner 

 frontal hair; (6), middle frontal hair; (7), outer frontal hair; (8), sutural hair; (9), 

 trans-sutural hair; (10), terminal hair of antenna; (11). antennal hair; (12). hasal 

 hair; (13), sub-basal hair; (14), supraorbital hair. B, Tip of antenna. 



