. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. Il] EXTERNAL FEATURES AND SKELETON 17 and are barely visible when the mouth is closed. The basal joint or cardo (c) is somewhat twisted. The distal joint or stipes (st) is longer and wider. It carries on its distal end two freely movable processes or lohes. Of these, the otiter lobe or palp (p) is curved, hairy, and only moderately pointed. It is obviously an organ of touch. The inner lobe {il) represents the lacinia and galea of more typical mandibulate insects, fused together. It has a rather flattened base, from which p
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. Il] EXTERNAL FEATURES AND SKELETON 17 and are barely visible when the mouth is closed. The basal joint or cardo (c) is somewhat twisted. The distal joint or stipes (st) is longer and wider. It carries on its distal end two freely movable processes or lohes. Of these, the otiter lobe or palp (p) is curved, hairy, and only moderately pointed. It is obviously an organ of touch. The inner lobe {il) represents the lacinia and galea of more typical mandibulate insects, fused together. It has a rather flattened base, from which project six large, sharply pointed and somewhat curved teeth, occupying the outer two-thirds. The inner third forms a small lobe or tubercle clothed with long sensory hairs. The inner lobe is probably both prehensile and tactile in function. Mastication is performed almost entirely b"" the Fig. 5. Labium of Aeschna brevistyla Raiub. ( x 10). eh end-hook; II lateral lobe; m mentum; mh movable hook; ml median lobe; sm sub-mentum; fsq squame. Original. The Labium (figs. 5, 6). In all insects this organ is formed by the fusion of the second maxillae. It is attached basally to the gula, and represents the paired appendages of the sixth or last head-segment. In the Odonata, both larvae and imagines, it is of a highly specialized form. The question of the homologies of its parts has given rise to much controversy. The conflicting views are dealt with in the account of the larval mask on p. 80. In the imago, a considerable variation of form is seen in the labia of different groups. In all cases, however, we can recognize the same principal parts. There is a broad short base with a projecting middle portion, at the sides of which are articulated T 2. 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
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishercambridgeenguniver
