CVLICWM 



111 



skeleton of the head, projects forwards, under cover of which the mouth 

 appendages appear as a median proboscis and two lateral palpi. 



These mouth parts are, made up of the following {vide Fig. 22, p. 224): — 



1. Labrum, or upper lip, with which is combined the epi pharynx to form 

 the labrum epipharynx. 



2. The mandibles. 



3. The first pa,ir of maxillae, to which the palpi belong. 



4. The hypopharynx. 



5. The second pair of maxillae, which have united together to form the 

 lower lip or labium. 



The labrum-epipharynx commences at the head end as two separate chitin- 

 ous structures : the more dorsal, continuous with the clypeus, is the labrum, 

 and the more ventral, continuous with the chitinous lining of the mouth 

 cavity, is the epipharynx; the part in the proboscis forms a deep groove, 

 open venfrally.^ In the female its free end is sharp and pointed; in the male 

 it is truncated. 



The mandibles are absent 

 in the males, while in the 

 female they appear as yellow 

 delicate chitinous blades, the 

 base of which is attached to 

 the sides of the labrum, and 

 the apex is knife-shaped, with 

 its edge serrated by thirty- 

 one fine teeth {vide Fig. 23). 



The first maxillae are chiti- 

 nous rods attached posteriorly 

 to the side of the base of the 

 labium, which is here swollen, 

 and carries on its outer angle 

 the palp. It is continuous 

 posteriorly with a chitinous 

 bar, which runs backwards 

 into the head, and affords 

 attachment to several mus- 

 cles. The free extremity of 

 the maxilla has thirteen teeth 

 iTjide, Fig. 24, p. 225). 



The maxillary palps pro- 

 ject on either side of, and 

 dorsal to, the proboscis . They 

 are five-jointed, and covere(i 

 with scales. In the male the 

 distal end of the third segment 



is broadened, and the whole fourth and fifth segments are broad and flat, 

 giving a spatulate appearance to the tip. The length of these palpi varies in 

 the different genera of the Culicidne, as will be mentioned under the heading 

 of Classification. 



The hypopharynx takes its origin iust above the base of the labium in a 

 solid mass of chitin, which is pierced by the salivary duct, which is a canal 35 

 to 36 /X in diameter. In the male the hypopharynx is fused with the labium. 



The second maxillae are united together to form a lower lip, or labium, 

 which is curved dorsally so as to form a deep groove, in which the first maxillae 

 lie ventrally and laterally, with the hypopharynx situated dorsally and 

 mesially, and the labrum-epipharynx dorsally with the mandibles on either 

 side. The distal end carries two short segments called ' labellae,' which are 

 movable on hinge-ioints. Between these labellae there is a projection of 

 the labium connected with them by a thin membrane— Dutton's membrane 

 — which is stretched during the act of biting. Through this membrane 

 filarial embryos escape from, the interior of the labium. The labium itself 



Fig. 382. — The Occiput and Scutellum of 

 AN Anopheline Mosouito, to show the 

 Scale Characters. 



At the side is seen the lateral aspect of 

 the vertical scales. 



(After Theobald, from ' The Cuhcidae of 

 the World.') 



