. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. STRUCTURE 405 either along the ventral margin of the head or along the hind edge of the pronotum (the dorsal plate covering the first segment of the thorax) or in both places. The presence or absence of these combs and the number of teeth in them is of considerable use in identification of species. The legs of fleas are very long and powerful, and at first glance seem to possess one more segment than do the legs of other in-. FiQ. 177. The Indian rat flea, Xenopsylla cheopis, male. X 60. (After Jordan a
. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. STRUCTURE 405 either along the ventral margin of the head or along the hind edge of the pronotum (the dorsal plate covering the first segment of the thorax) or in both places. The presence or absence of these combs and the number of teeth in them is of considerable use in identification of species. The legs of fleas are very long and powerful, and at first glance seem to possess one more segment than do the legs of other in-. FiQ. 177. The Indian rat flea, Xenopsylla cheopis, male. X 60. (After Jordan and Rothschild.) sects. They really consist of the usual number of segments, however, but are peculiar in the enormous development of the first segments of the legs (coxse), which in most insects are quite insignificant (Fig. 179). The shape of the sternal plate to which the coxse are attached is suggestive of still another segment. The great development of the coxse as well as of the other seg- ments of the leg gives unusual springiness and consequently enormous jumping power. The human flea, Pulex irritans, has been observed by Mitzmain to jump 13 inches horizontally and seven and three-fourths inches vertically. An equivalent jump for a man of average height would be over 450 feet horizontally and over 275 feet vertically! The jumping power must over- come to some extent the disadvantage of winglessness and render migration from host to host comparatively easy. All the legs. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Chandler, Asa Crawford, 1891-. New York, J. Wiley
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