. L'histoire naturelle de Cambridge. Zoologie. 282 ORTHOPTEPA. Fig. 168.-patte postérieure du Porthetis sp. Rhône-Alpes. (Fig. 185, C). Les pattes sont parfois très longues ; leurs fémurs, plus épais vers la base, sont en général particulièrement fabrique de sculptures, carènes longitudinales ou des rainures, qui sont plus ou moins dentée, et sont également très fréquemment avec de courtes lignes parallèles une réunion similaire à la ligne longitudinale centrale angles, de manière à donner lieu à une tendance bien marquée ; où les jambes sont plus larges le motif est plus complexe (Fig. 168). Les tibias Lear deux rangées d'épines sur leur partie supérieure ou

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. The Cambridge natural history. Zoology. 282 ORTHOPTEPA. Fig. 168.—Hind leg of Porthetis sp. Transvaal. (Fig. 185, C). The hind legs are occasionally very long; their femora, thicker towards the base, are generally peculiarly sculp- tured, bearing longitudinal ridges or grooves, which are more or less spinose, and are also very frequently marked with short parallel lines meeting a central longitudinal line at similar angles, so as to give rise to a well-marked pattern ; where the legs are broader the pattern is more complex (Fig. 168). The long tibiae Lear two rows of spines on their upper or posterior edge ; this part of the hind leg can be completely bent in under the femur. The stigmata consist of one prothoracic, one meta- thoracic, and eight abdominal pairs. In reference to the ocelli, which are shown in Fig. 166, we may remark that the Acridiidae is one of the large groups of Insects in which the coexistence of compound and single eyes is most constant, though in some of the wingless forms the ocelli are very imperfect. "Ve know at present of nothing in the habits of Acridiidae to render two kinds of eyes specially neces- sary. We shall subsequently see that a similar condition in regard to the function of hearing is believed to exist in this family. Acridiidae are remarkable amongst the Orthoptera for the possession of air sacs or vesicular dilatations in the interior of the Insect in connexion with the tracheae (Fig. 176). Such vesicles are found in many of the higher winged Insects, but not in larval forms, or in those that are destitute of powers of flight.^ They, no doubt, assist the Insect in its movements in the air. The body of a large grasshopper or locust is naturally of considerable weight, and it is more than probable that true flight can only be accomplished when these vesicles are dilated and filled with air. The exact mode in which the sacs are dilated is not known; possibly it may be accomplished by the elasticity of the structure of t

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• bookcentury1800
• bookdecade1890
• booksubjectzoology
• bookyear1895