Entomology : with special reference to its biological and economic aspects . e of the internal tentorium of the head has al-ready been referred to. In thethorax three kinds of chitinous in-growths may be distinguished ac-cording to their positions : (i) phrag-mas, or dorsal projections; (2)apodemes, lateral; (3) apophyses,ventral. The phragmas (Fig. 59)are commonly three large plates,pertaining to the meso- and meta-thorax, and serving for the originof indirect muscles of flight inLepidoptera, Diptera, Hymenopteraand other strong-winged orders. Theapodemes are comparatively small in
Entomology : with special reference to its biological and economic aspects . e of the internal tentorium of the head has al-ready been referred to. In thethorax three kinds of chitinous in-growths may be distinguished ac-cording to their positions : (i) phrag-mas, or dorsal projections; (2)apodemes, lateral; (3) apophyses,ventral. The phragmas (Fig. 59)are commonly three large plates,pertaining to the meso- and meta-thorax, and serving for the originof indirect muscles of flight inLepidoptera, Diptera, Hymenopteraand other strong-winged orders. Theapodemes are comparatively small in-growths, occurring sometimes in allthree thoracic segments, though usu-ally absent in the prothorax. Theapophyses occur in each thoracic seg-ment as a pair of conspicuous proc-esses, which either remain separateor else unite more or less; leaving, however, a passage for theventral nerve cord. These endoskeletal processes serve chiefly for the origin ofmuscles concerned with the wings or legs, and are absent insuch wingless forms as Thysanura, Pediculidse and Transverse sections of thethoracic segments of a beetle,Goliathus, to show the endo-skeletal processes. A, pro-thorax; B, mesothorax; C,metathorax; a, a, apophyses;ad, apodeme; p, phragma.—After KoLBE. ANATOMY AND PHYSIOLOGY 51 Fig. 60. tb Some ambiguity attends the use of these terms. Thus somewriters use the term apodemes for apophyses and others applythe term apodeme to any of the threekinds of ingrowths. Legs.—In ahnost all adult insects andin most larvae each of the three thoracicsegments bears a pair of legs. The legis articulated to the sternum, episternumand epimeron and consists of five seg-ments (Fig. 60). in the following order:coxa, tiocJiaiifcr, femur, tibia, coxa, or basal segment, often has aposterior sclerite, the trocluintinc} Thetrochanter is small, and in parasiticHymenoptera consists of two subseg-ments. The femur is usually stout andconspicuous, the tibia commonly
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
