. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. II] EXTERNAL FEATURES AND SKELETON 27. used in the act of capturing prey on the wing. A difference of opinion prevails on this point. The difhculty of making direct observations is obvious, and has not so far been satisfactorily overcome. Each leg consists of five segments or joints, called (from the base outwards) coxa, trochanter, femur, tibia and tarsus. There is no trochantine. The coxa [ex) is a short truncated cone, with its rounded base inserted into a large hollow, the acetabulum, situated in the side of the sternu
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. II] EXTERNAL FEATURES AND SKELETON 27. used in the act of capturing prey on the wing. A difference of opinion prevails on this point. The difhculty of making direct observations is obvious, and has not so far been satisfactorily overcome. Each leg consists of five segments or joints, called (from the base outwards) coxa, trochanter, femur, tibia and tarsus. There is no trochantine. The coxa [ex) is a short truncated cone, with its rounded base inserted into a large hollow, the acetabulum, situated in the side of the sternum, close to the pleurum. The bases of insertion of the legs of the Dragonfly are very closely approxi- mated, particularly in the cases of the middle and hind-legs (fig. 1 b). The trochanter (tr) is a short and rather slender joint, having a very short upper surface, so that its distal end runs obliquely downwards, and the articulation with the femur is correspondingly modified. A transverse constriction divides the tro- chanter into a shorter basal and a longer distal portion. An armature of short thick blunt teeth or tubercles may be present. The femur {fm) is the strongest j oint in the leg. It is a cylindrical, fairly stout, long joint, strongly armed with at least two rows of spines or tubercles. The tibia (fb) is generally somewhat longer, and much slenderer than the femur; it also is armed with two rows of spines, varying greatly in number, size, and arrangement. The tarsus {ts) is the short slender terminal segment. In all living Dragonflies, it con- sists of three joints, of which the basal is the shortest, the distal the longest. In the fossil genus Tarsophlebia (fig. 158) there were four joints, the basal being the longest. The joints of the tarsus are armed with small, closely-set spines continuing the lines of the tibial armature. The tarsus ends distally in a pair of strong diverging claws (cl), each of which usually bears a well-developed inferior tooth. Between
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