102 



310 SQUI TOES 



needed to hold it. It requires an effort, in fact, for the 

 Anopheles larva to descend (which it apparently never 

 does up to the period of the final larval stage, except 

 when alarmed), while it requires an effort for the Cnlex 

 larva to ascend. 



Structurally the differences between the half-grown 

 larvje of Culex and Anopheles are well shown in Figs. 19, 

 19a, and 20. The great size of the head of Culex, as con- 

 trasted with the small head of Anopheles, is a most strik- 



-grown Larva of Anoplieles maailipennis ; enlarged. 

 (Author's illustration.) 



ing difference. The very long respiratory siphon (as Miall 

 calls it) of Culex contrasts markedly with the short one 

 of Anopheles. The arrangement of the hairs is entirely 

 different ; the branching of the hairs of Anoplieles, as 

 contrasted with the simple hairs of Culex and the little 

 paired star-shaped (apparently branchial) tufts on the 

 dorsum of Anopheles, is entirely absent with Culex. 

 The flaps at the tail end of the body are similar in num- 

 ber, but are held in a somewhat different position. 



