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XVIII. — On a Possible Stridulating Organ in the Mosquito. [Anopheles maculipennis, 

 Meig.) By A. E. Shipley, M.A., and Edwin Wilson, F.E.S. Communicated 

 by Sir John Murray, K.C.B. (With a Plate.) 



(Read 3rd March 1902. Issued separately 24th April 1902.) 



At the base of the wings of Anopheles maculipennis, Meig, is a small quadrilateral 

 area (fig. 2, Plate) which has escaped the notice of the systematist, since the nervures 

 in which he is interested lie almost entirely beyond the area in question, and which 

 has escaped the notice of the morphologist, because it presents to him but a confused 

 outline of meaningless ridges and intervening depressions of no structural importance. 

 If, however, the well-preserved wing of a mosquito, whilst still attached to the thorax, 

 be examined, a very curious apparatus can be made out, lying across the centre of the 

 said quadrilateral area which is bounded posteriorly by the alula.* This apparatus lies 

 at about equal distances from the anterior and the posterior edge of the wing, and 

 divides the base of the wings roughly into two halves. 



The arrangement of the apparatus is not quite constant in different specimens ; 

 details vary, but the following points can in all cases be made out. It should, however, 

 be mentioned that the apparatus is very minute ; that it lies very close to the thorax, 

 hence, if the wings be cut off, it is almost certainly destroyed, and thus there is 

 small chance of seeing it in a detached wing ; that it is only visible when the wings 

 are extended, a position in which it is not always easy to mount the insect ; and 

 finally, that when the wings are at rest and folded back over the abdomen, the 

 details of the apparatus are obscured and become confused in a mass of ridges and 

 furrows, from which they can hardly be disentangled by the eye. The presence of 

 the striated scales on some of the ridges of this part of the wing still further serves 

 to obscure the parts in question. 



The structure of the apparatus is very complex, but can be easily realised from 

 an inspection of fig. 1, Plate, which represents the right half of the thorax of 

 Anopheles maculipennis with the base of the right wing and the right halter. To 

 bring out the structures of the parts in question, we have coloured them, and it will 

 be seen at a glance that they fall into two series, an anterior one, which we have 

 coloured blue, and a posterior set of structures, which we have coloured yellow. 



The anterior system consists of a slightly movable bar A, which covers a 

 thickening in the tissue of the wing. This last-named ultimately passes into the sub- 

 costal nervure. The bar extends from the articulation of the wing to the humeral 



* Nuttall and Shipley, J. Hygiene, i., 1901, p. 474. 

 TRANS. ROY. SOC. EDIN., VOL. XL. PART II. (NO. 18). 3 i 



