83 



Taeniorhynchus, as much as twelve in some cases. 

 Draw accurately by measurement (eye-piece micro- 

 meter) a number of syphon tubes of different 

 Culex larvae. Note that marked variations in 

 different species exist (Fig. 22). 



Note two rows of spines on the posterior 

 aspect of the syphon tube, starting from the base 

 and extending a variable (in different species) 

 distance up the syphon tube ; note that they 

 differ in number and length, etc., in different 

 species. The spines appear serrated or compound, 

 according to the angle they are viewed from, and 

 differences may be supposed to exist which depend 

 upon this fact. In some species (certain carnivorous 

 , or cannibal larvae) a large fan of hairs projects 

 posteriorly in the medium line from the syphon 

 tube. In certain species the syphon tube is of 

 enormous size, and may attain to one-third the 

 length of the larva. 



The Antennae. — Note in the case of most 

 typical Culex larvae that the antennae are large 

 conspicuous objects ; note a basal, medial, and 

 terminal portion, and a large bunch of feathered 

 hairs arising at the junction of the two first- 

 named portions ; note also large single and stout 

 hairs from the more terminal portion ; note spines 

 on the body of antenna. 



Examine the Antennae of various Larvae. — Note 

 in some cases that the antennae are more rudi- 

 mentary (Stegomyia, Anopheles). In the case of 

 Stegomyia (as far as described) they are small and 

 spineless, and possess only a small hair arising 

 from a papilla, which may be single or in three 

 or four branches. Make drawings (using eye- 



