198 MEDICAL ENTOMOLOGY 



bunches of hairs are spread out and project well in front of the 

 clypeus ; they do not present any special modifications of taxonomic 

 value. In predaceous larvae the hairs are much fewer in number, and 

 are much stouter, and may be serrated ; such larvae use their feeding 

 brushes in seizing their prey. (James.) 



Between the feeding brushes, in the middle of the ventral margin, 

 there is a bunch of seven stouter hairs, directed forwards like a plume. 

 These move with the feeding brushes, as they arise from the same mem- 

 brane as that in which the apodemes of the latter are developed. 



The mandibles (Plate XXXV, fig. 1) are stout, somewhat quadrilateral 

 appendages, consisting of a single joint, the two forming the lateral 



boundaries of the mouth aperture. The anterior and 

 The Mandibles and , *'**. t j i i i -,- 



Maxillae inner angle is armed with a set of dark brown chitmous 



teeth, apparently of little use in most anopheline 

 larvae, which are surface feeders. On the anterior and external angle 

 there is a gitmp of four strong curved hairs, bent inwards over the teeth ; 

 these are used in cleaning the brushes. On the internal border there 

 is a fringe of fine hairs, those of the two sides meeting when the 

 mandibles are folded inwards. In the normal resting position the teeth 

 of the mandibles lie near one another and immediately in front of 

 the mental plate. They can be rotated outwards on their posterior and 

 external angles through an angle of 90 or so. 



The maxillae (Plate XXXV, fig. 4) are partly covered by the 

 mandibles, and are neither easy to see when in situ nor to dissect out. 

 Each consists of a flattened and irregular chitinous plate, covered 

 with fine stiff hairs which are mainly directed towards the anterior and 

 internal angle, and are used, like those of the mandibles, in cleaning the 

 feeding brushes. On the outer side of the maxilla there is a small 

 spindle-shaped palp, the distal end of which is surmounted by three small 

 stout spines, connected together by a membrane. The palp lies internal 

 to the antenna, and is the most conspicuous part of the appendage. 

 Neither mandibles nor maxillae afford useful distinguishing characters. 

 The maxillary palp is small in most species of Culex and Stegomyia. 



The mzntal plate (Plate XXXIV, fig. 4) lies in the middle line, at the 

 posterior end of the mouth area, and between the two mandibles. It is 

 small, triangular, and heavily pigmented, having its apex pointed and 

 directed forwards, and its sides divided into a number of coarse serrations. 

 This structure probably represents the rudiments of two fused maxillae, 

 and is indeed termed the labial plate by some writers ; others have pointed 

 out its correspondence with the rnentum of other larvae. In reality the 



