MOUTHPARTS OF MOSQUITO 37 



conical more or less constricted at base. It presents no noteworthy modifica- 

 tions. Its surface is usually naked and smooth, or, due to the presence of very 

 fijie hairs, pruinose. In some cases it is densely clothed with scales, and in one 

 genus, Jollotia, it bears many scattered coarse hairs, particularly towards the 

 margin. 



THE PROBOSCIS. 



All true mosquitoes have a long proboscis of complex structure ; it is used as 

 a sucking-organ, and in the females of many species as a piercing organ as well. 

 It is most highly organized in the females with blood-sucking habits. The organ 

 was already carefully studied by the early workers with the microscope, among 

 whom may be particularly mentioned Leeuwenhoek, Swammerdamm, Barth, 

 and Reaumur. These early investigators only studied the mouthparts per se, 

 without thought of their relations to the mouthparts of other insects. It was not 

 until after the study of entomology had been put on a firm footing by systematists, 

 and the significance of the mouth-parts of insects in classification had been 

 pointed out by Fabricius, that attempts were made to homologize the mouthparts 

 of the different orders of insects. Savigny, in 1816, already developed the idea 

 that the mouthparts of all insects were reducible to the same general plan of 

 those of the chewing insects, and that these mouthparts were the serial homo- 

 logues of locomotory appendages. The belief that the mouthparts of the mosquito 

 (and of the Diptera in general) are homologous with those of mandibulate 

 insects has been very generally accepted by modem entomologists. It was not, 

 however, until about 30 years ago that any exact knowledge of the organization 

 of the proboscis of the mosquito was reached, the previous analyses having been 

 unsatisfactory from the scientific point of view, and conflicting. In 1880 two 

 careful studies of the mouthparts of the mosquito and of other Diptera, carried 

 out independently with strictly modern methods, were published by Dimmock 

 and by Meinert. Both these works describe very completely the anatomy of the 

 proboscis and related parts; the interpretation of the mouthparts by the two 

 authors, however, is quite different. Dimmock followed the generally accepted 

 idea and homologized the components of the proboscis with the mouth-organs of 

 mandibulate insects. Meinert, on the other hand, concluded that no such 

 homology exists and presented an entirely different interpretation. The studies 

 of Kellogg, of the development of the mouthparts of the dipterous imago within 

 the larva, show conclusively that the generally accepted view is correct and essen- 

 tially as presented by Dimmock. It seems desirable, however, to present briefly 

 Meinert's views, and also those of other authors when at variance with the ac- 

 cepted interpretation of the facts. Additions to our knowledge of the mouth- 

 parts made since by different workers will be also considered. Dimmoclc's de- 

 scription of the mouthparts of the female and male Culex is so clear and full 

 that we reproduce it herewith, together with the excellent plate elucidating the 

 structures (pi. II, opposite page 36). 



In the female : 



" The mouth-parts which form the proboscis of the female Culex, as I have 

 found them by study of C. rufus, C. ciliatus, and C. fipiens, consist of a labrum 

 4 



