CULICID^ 



781 



On the ventral surface of the basal lobe is the tubercle or lobe, called the 

 claspette, while from their inner margin, near the base, a pair of claspers 

 called harpagones, and more distally another pair, the harpes, project. Just 

 at the junction of the two basal lobes are another pair of lobes — the setaceous 

 lobes — which are believed to be the rudimentary ninth segment. The unci 

 are absent in the Anophelinae, but present as a pair of ventral processes in the 

 Culicinse. In the female there are the flap-like ovipositors. 



The flat abdominal scales of the other Culicidse are absent in the Anophelinae, 

 except in one genus. 



Internal Anatomy, — A few points with regard to the internal anatomy of 

 the mosquito may be mentioned. 



Alimentary Canal. — The alimentary canal consists of: (i) Mouth; 

 (2) buccal cavity; (3) pharynx, or pumping organ; (4) oesophagus and its 

 pouches; (5) oesophageal valve, or proventriculus ; (6) mid-gut; (7) ileum; 

 (8) colon; (9) rectum; (lo) anus [vide Fig. 385). 



Fig. 385. — The Alimentary Canal of Anopheles maculipennis Meigen. 



(After Nuttall and Shipley, Journal of Hygiene.) 



I, Mouth and buccal cavity; 2, pharynx; 3, oesophagus; 4, dorsal and ventral 

 oesophageal diverticula; 5, proventriculus; 6, salivary glands; 7, narrow 

 portion of ventriculus; 8, so-called stomach; 9, Malpighian tubules; 10, intes- 

 tine; 11, rectum; 12, anus. 



1. Mouth. — The mouth is the place where the maxillae, mandibles, labrum- 

 epipharynx, hypopharynx, and palps fuse together. 



2. Buccal Cavity. — This extends from the mouth to the valve between it 

 and the pharynx, and is lined with chitin, and has an upward and backward 

 direction until it approaches the pharynx, when it turns suddenly upward. 

 There is a portion of its roof which possesses a thinner cuticle than the rest 

 of the buccal cavity, and has been called the soft palate. This structure 

 possesses two spines directed downwards into the lumen of the cavity, and has 

 attached to it five pairs of palatal muscles. It is thought that as this mem- 

 brane is wrinkled, and has muscles attached to it, it may indicate that it is 

 used for suctorial purposes. Posteriorly^ there is a valve between the buccal 

 cavity and the pharynx, lying on a level just behind the posterior end of the 

 clypeus. This prevents the return of fluids to the mouth during pumping. 

 Annett and Button described a complicated sense-organ at the junction of the 

 buccal cavity and the pharynx, but this has not been confirmed. 



3. Pharynx. — The pharynx extends from the posterior end of the buccal 

 cavity to nearly the posterior end of the head, where it ends in the oesophagus. 

 It is considerably larger in the female than in the male, because the former 

 sucks blood, while the latter does not. The anterior portion is tubular, and 

 passes through the nerve ring between the supra- and infra-oesophageal 

 ganglia. The posterior portion is triangular, and has a chitinous wall arranged 

 into three plates, one dorsal and two latere- ventral. 



Posteriorly, near the oesophagus, the triradiate pharynx is surrounded by 

 a sphincter muscle, and the chitin of this portion is marked by ridges, which 

 end in very fine spines, making a comb-like appearance, and possibly acting 

 as a strainer. The three chitinous plates have powerful muscles attached 



