. A practical study of malaria. er. The mesothorax, comprising the bulk of the ETIOLOGY 83 thorax, is covered by the scutum. Behind the scutum and theorigin of the wings is the transverse scutellum, behind whichis the metathorax or postscutellum. The abdomen is larger than the thorax, depressed beingbroader than deep, and is composed of nine segments. Theupper and under surfaces of each segment are somewhat rigid;laterally the membrane is softer and contains the openings often respiratory tubes or stigmata. The anus opens ventrallyupon the eighth segment. The ninth segment bears the exter-nal
. A practical study of malaria. er. The mesothorax, comprising the bulk of the ETIOLOGY 83 thorax, is covered by the scutum. Behind the scutum and theorigin of the wings is the transverse scutellum, behind whichis the metathorax or postscutellum. The abdomen is larger than the thorax, depressed beingbroader than deep, and is composed of nine segments. Theupper and under surfaces of each segment are somewhat rigid;laterally the membrane is softer and contains the openings often respiratory tubes or stigmata. The anus opens ventrallyupon the eighth segment. The ninth segment bears the exter-nal organs of generation. The legs, six in number, very long and slender, comprisethe following joints: The coxa and trochanter, the femur, thetibia, and the five-jointed tarsus, the distal joint of which bearsthe claws. The wings originate from the posterior portion of the meso-thorax. The wing venation is best understood by referring to hwiwalcrossvbn ,-jWa). AUXIUAffrYOI ffiVDH 3?? VON / 4p/Em / jCTDiriorjr SUBWWGtMALCOl. Fig. —Diagram of the wing of a mosquito {Culex pipiens), with names of veins, cells, etc. (Coquillett). the illustration (Fig. 38). The wing scales are of importancein classification. From the metathorax arises the pair of halteres or balancers,club-shaped organs, rudiments of a second pair of wings. Sup-plied with one of the largest nerves of the body, they are re-garded as sense organs. Anopheles is distinguished from culex especially by the palpi,which in the former is in both sexes almost as long as theproboscis, in the latter the palpi of the female being very is more slender, the head is smaller, and the legs 84 THE STUDY OF MALARIA more delicate. The palpi of the female being thickly scaledand lying close to the proboscis give the impression of a thickbeak, which contrasts strongly with the short palpi and slenderproboscis of the culex. The wings of the anopheles arespeckled, which is not the case with any of the common spec
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmalaria, bookyear1909
