. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. THE LARVA OR NYMPH [CH. to one another like the thumb and forefinger, and serve to grip the prey. The suh-mentum {sm), in the position of rest, is directed backward along the ventral surface of the thorax, between the bases of the legs. At its distal end it bears a strong hinge [h), which functions as an elbow-joint, and serves to articulate the raentum. The mentum {m) lies ventrally below the sub-mentum, but is directed forward, so that its distal end lies just below the mouth. Lateral squames are absent. Galea and lacini
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. THE LARVA OR NYMPH [CH. to one another like the thumb and forefinger, and serve to grip the prey. The suh-mentum {sm), in the position of rest, is directed backward along the ventral surface of the thorax, between the bases of the legs. At its distal end it bears a strong hinge [h), which functions as an elbow-joint, and serves to articulate the raentum. The mentum {m) lies ventrally below the sub-mentum, but is directed forward, so that its distal end lies just below the mouth. Lateral squames are absent. Galea and lacinia are absent or vestigial, but the base of an original ligula is represented by the median lobe (ml), which is fused with the mentum, and forms. Fig. 30. Concave or spoon-shaped mask of Synthemis eustalacta Burm. d toothed distal border of lateral lobe; m mentum; mA movable hook; sm sub-mentum. ( X 8.) Original. its mid-anterior border. Movably articulated with the mentum, on either side of the reduced median lobe, is a strong lateral lobe (11) formed by the palp. These two lateral lobes are very highly specialized, and form the actual organ of prehension. Each carries, at its outer distal angle, a strong movable hook (mh). The end-hook of the imaginal labium, which is fixed, is represented in the labial mask by the apex {a) furnished with a small hook in some forms, but not in most. The presence of a movable hook and an apex enables us to divide the margin of the lateral lobe into three portions, whose different degrees of development in the various groups lend to them considerable taxonomic 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 Tillyard, Robin John, 1881-1937. Cambridge [Eng. ] : University Press
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