MOSQUITOS OF THE PALAEARCTIC REGION. 331 



17. Mesosome with two divisions, one of which carries two or three short teeth 



tipuliformis, Theo. 

 Mesosome (as seen from above) with three simple divisions 



18. Second division of mesosome simple . . 

 Second division of mesosome divided into several teeth 



19. Second division of mesosome very broad and plate-like 

 Second division of mesosome narrow and hook-like . . 



Larvae. 



virgatipes, Edw. 



perexiguus, Theo. 

 laurenti, Newst. 



fatigans, Wied. 

 pipiens, L. 



1 . Siphon rather less than three times as long as broad . . . . . . 2 



Siphon at least four times as long as broad, generally much more . . 3 



2. Siphon pale, all the tufts arranged in a slightly zigzag mid-ventral 



line ; tip of antennae black and much narrowed . . pnsillus, Mcq. 



Siphon blackish ; ventral tufts in three or four pairs, the members of 

 which are widely separated ; two lateral tufts also present ; antennae 

 all pale, tip scarcely narrowed . . [nebtdosus, Theo.], impudicus. Fie. 



3. Comb of eighth segment with 4-8 large sharp teeth . . . . . . 4 



Comb of eighth segment with numerous small scales in a triangular patch. . 5 



4. Siphon with a dark ring at one-third of its length ; head very dark ; 



pecten-teeth 6-9 quasigelidus, Theo. 



Siphon and head pale ; pecten teeth only 2-3 . . hitaenioyhynchus, Giles. 



5. Siphonal tufts 8-10, in a zigzag ventral row, the first two or three tufts 



between the pectens . . . . . . . . . , . . laticindus, Edw. 



Siphonal tufts more or less paired, none between the pectens . . . . 6 



6. Siphon 6-7 times as long as its breadth at the base ; or, if a little shorter 



(C. tipuliformis), the pecten teeth have short basal denticles only . . 7 

 Siphon 4-5 times as long as its breadth at the base ; pecten teeth with 

 rather long denticles extending more than half their length . . . . 12 



7. Pecten spines strong, curved, rather wide apart, with small basal denticles 



tipuliformis, Theo. 

 Pecten spines smaller, straight and closer together, generally with more 

 numerous denticles . . . . . , . . . . . . . . . . 8 



8. Siphon distinctly enlarged at the tip, tufts few and small . . apicalis, Adams. 

 Siphon not enlarged at the tip . . . . . . . . . . , . ... 9 



9. Siphonal tufts rather numerous, some much longer than the diameter of 



the siphon . . . . . . . . . . . . . . . . . . 10 



Siphonal tufts fewer, none longer than the diameter of the siphon . . . . 11 



10. Antennae pale except on the portion beyond the subapical bristles, which 



is nearly as long as the part between these bristles and the tuft 



mimeticus, Noe. 

 Antennae entirely, or at least more than half, dark, subapical bristles 

 quite near tip hortensis, Fie. 



11. Antennal tuft at two-thirds; siphonal tufts all subventral (paired) 



tritaeniorhynchus, Giles. 

 Antennal tuft beyond two-thirds ; two pairs of siphonal tufts lateral 



perexiguus, Theo. 



12. Siphon about 5x1, pecten teeth averaging 12-15 . . . . pipiens, L. 



Siphon scarcely 4 X 1, pecten teeth averaging 9 .. .. fatigans, Wied. 



