STRUCTURE, CLASSIFICATION, AND KEYS 23 



3a Abdominal segments 4 and 5 with two conspicuous tufted hairs 

 (hairs 2 and 0) anterior to palmate hair: Anopheles crucians 

 Wied. (see Fig. VI, C). 



3b Abdominal segments 4 and 5 with but one conspicuous hair (the 

 antepalmate hair or hair 2) anterior to palmate hair (see Fig. 

 VI, D): 4 



4a Anterior internal clypeal hairs well separated at base (see Fig. 

 VI, A) : Anopheles quadrimaculatus Say. 



4b Anterior internal clypeal hairs close together at base (see Fig. 



VI, B) : 5 



5a Anterior internal clypeal hairs with minute branches on outer 

 half (see Fig. VI, B) : Anopheles walheri Theob. 



5b Anterior internal clypeal hairs without minute branches on outer 

 half: Anopheles punctipennis Say 



6a Head (in last stage) elongate elliptical: Uranotaenia sapphirina 

 O.S. 



6b Head rounded or transverse, not elongate: 7 



7a Anal segment with a ventral brush (see Fig. VII) : 8 



7b Anal segment without a ventral brush ; never more than ten hairs 

 in its place: Wyeomyia smithii Coq. 



8a Air-tube without pecten (two rows of spines on posterior edge 



at base) : 9 



8b Air-tube with pecten (see Fig. VII) : 10 



9a Air-tube truncated, with a saw-toothed projection: Mansonia per- 

 turhans Walk. 



9b Air-tube normal, not so modified: Orthropodomyia signifera Coq. 



9c Air-tube stout, conically tapered outwardly, about two and one- 

 half times as long as wide: Megarhinus septentrionalis D. & K. 

 10a A single paired hair-tuft on air-tube [rarely with additional hairs 



(see Fig. VII)]: 16 



10b Air-tube with several tufts (if lacking, air-tube is much elon- 

 gated) : 1 1 

 11a Anal segment with hair tufts along the lateral edge preceding the 

 posterior brush ; the scales of the eighth abdominal segment form- 

 ing a triangular patch, incomplete at the base of the air-tube: 

 Theobaldia morsitans Coq. 

 lib Anal segment with hair tufts in posterior brush only: 12 

 12a The scales of the eighth abdominal segments replaced by a single 

 straight row of chitinous bars ; a row of twelve hair tufts along the 

 posterior edge of the air-tube, extending from a point before the 

 middle to a short distance from the tip; the hairs on the anterior 

 edge of the prothorax extending beyond the antennae: Theobaldia 

 melanurus Coq. 

 12b The scales of the eighth abdominal segment distinct and sepa- 

 rate: 13 

 13a Antennae with the tuft (see Fig. VII) at the middle; a pair of 

 long hairs at the middle of the anterior-lateral edge of the air 

 tube: Culex territans Walk, (was restuans Theob.). 



