36 



which species my observations have been limited, measures 2y 2 milli- 

 meters; that of the species observed by Reaumur measured according 

 to that author, one French line; and as our mosquito oftentimes 

 drives its sting nearly to its very root, it can readily reach a blood-ves- 

 sel at a depth not exceeding 1/5 of a centimetre. In the interior of the 

 sheath are two tubes, lying apparently loose at the bottom of its conca- 

 vity; I have observed them presenting a tortuous direction, and uniting 

 into a common trunk within the concavity of the pedicle. I believe it 

 is through these tubes that the mosquito pours out the acrid saliva 

 which causes the burning sensation during its bite, and which, accord- 

 ing to naturalists, serves to render more fluid the blood which has to 

 run through the sucking apparatus. 



Within the sheath are contained five pieces: the principal one cons- 

 titutes the labrum or upper-lip, it is of horny consistance and prolonged 

 like a long spur, deeply grooved so as to form a canal opening upwards *) 

 and ending in a point like that of a tooth-pick cut out of a long slender 

 quill. This piece is rigid and presents on its outer surface a curious 

 design as if covered wth a net whose meshes, in relief, form small 

 parallelograms with acute angles pointing longitudinally. Perhaps within 

 those innumerable meshes might be lodged some particles of the blood 

 sucked by the insect. The other four pieces are paired, flexible setae, 

 two of them constituting the mandibles, and the others the maxillae. The 

 structure of the two pairs is very different in each. The mandibles are 

 concave inwardly, and have a tendency to maintain a curvilinear 

 direction ; their outer side is convex and presents transverse ridges ending 

 on their free border in very minute teeth. The point of the mandibles is 

 curved and armed to its very end with teeth which appear to be both sharp 

 and strong. The maxillae are inserted a little below the mandibles; they 

 present the appearance of a ribbon with its edges turned in like a seam, arm- 

 ed with a fringe of long delicate teeth ; its general aspect is that of a long 

 narrow blade of grass, ending in a broad double-edged point and strength- 

 ened by a longitudinal vein running all along its middle. All these 

 setae adapt themselves upon the stem of the labrum so closely that, after 

 the sheath has been removed and before the setae are dissociated, one 

 would never think that the round or oval rod, with its sharp, single 

 point, which comes into view is an assemblage of the five separate pieces 

 which I have been describing. 2 ) 



1) This is a misprint. I should read "downwards." 



2) The above description was written under the impression that only 

 5 mouth parts went to constitute the sting of the Cules mosquito, and of mos- 

 quitoes in general. Soon after writing this paper, however, I became aware of the 

 existence of a sixth seta, in accordance with the statements of modern entomologists. 

 — On closer observation too, I found that what I had described as one of the mandi- 

 bles, more properly applies to the hypopharynx, about the existence of which I was 



