. Bulletin of the Natural History Museum Zoology. Fig. 10 Diagramatic transverse sections of toe 4 of a. Lacerta agilis and b. Laceita oxycephala, showing differences in relative cross sectional area of phalanx and ventral Fig. 9 Digits of pes of lacertids in lateral view. a. Ground dweller. Lacerta agilis, digit 4. b-d. Climbing species, Lacerta oxycephala. digits 3. 4 and 5. e. Climbing species. Lacerta perspicillata showing alternative pattern of flexion in digit 5. deep and strongly recurved. The prominence on the terminal pha- lanx, to which the ventral tendon of the digit is att
. Bulletin of the Natural History Museum Zoology. Fig. 10 Diagramatic transverse sections of toe 4 of a. Lacerta agilis and b. Laceita oxycephala, showing differences in relative cross sectional area of phalanx and ventral Fig. 9 Digits of pes of lacertids in lateral view. a. Ground dweller. Lacerta agilis, digit 4. b-d. Climbing species, Lacerta oxycephala. digits 3. 4 and 5. e. Climbing species. Lacerta perspicillata showing alternative pattern of flexion in digit 5. deep and strongly recurved. The prominence on the terminal pha- lanx, to which the ventral tendon of the digit is attached, is situated well away from the centre of rotation of the claw, conferring considerable mechanical advantage (Fig. 17b). The tendon stands well away from the articulation when the claw is ventrifleeted; it also tends to do the same under the downflexed joint between phalanges 1 and 2 in digits 3 and 4 (Fig. 17b), and 2 and 3 in digit 5. Articulations within the digit except for the most distal one are simple, consisting of a single protruberance at the distal end of each phalanx that fits into a cup on the adjoining one. These confer substantial mobility in both the vertical and horizontal planes. As in ground dwellers, digits 2-4 can curve laterally and swing mesially around their base until their proximal phalanges are in line with their metatarsals. Unlike those of ground dwellers, the digits themselves can bend quite abruptly in a mesial direction, as a result especially of flexibility at their penultimate articulations but also, to some extent, of that at the articulations between phalanges 1 and 2 in digits 3 and 4 and that between 2 and 3 in digit 5 is not only lateromesially mobile at its base but also at other joints. Variations in the direction of kinking in toe 5 of lacertids Most climbing lacertids possess a pattern of kinking in toe 5 like that found in Lacerta oxycephala and described above (Fig. 9d, called here pattern A). However, a minority possess
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