12 



can recall a seemingly distinct difference in body and limb proportions). 



The locomotion of Gekkota outwardly resembles that of the Iguanomorpha 

 (elevated body posture). But their upper arms move in a horizontal plane, as 

 in the Scincomorpha, which \mdoubtedly is closer to the original locomotor 

 pattern. In the Iguanomorpha, this plane is more vertical (perhaps explain- 

 ing the curious similarity between such specialized forms as Phrynocephalus 

 and mammals - the formation of a prototype of the m. supraspinatus in the 

 form of the m. supracoracoideus accessorius (Fig. 5, C). The locomotion of 

 terrestrial gekkonids is much slower and clumsier than that of the Iguano- 

 morpha. Tliis is shown both by direct measurements of the speed of the 

 scincogekkonomorphans Phrynocephalus mystaceus and Ph. reticulatus, and the 

 analysis of their tracks.^ 



The similar movement of forelimbs of the Gekkota and Scincomorpha may be 

 due to the similarity in musculature. But the striking similar musculature 

 of the pelvis and thigh of these groups is still a mystery. Tlie crossing of 

 the muscle fibers of the m. pubo-ischio-femoralis internus in forms with 

 relatively short limbs (Scincomorpha) may be due to the necessity of increas- 

 ing the stride during locomotion. But the hindlimbs of the Gekkota, although 

 shorter than those of Iguanomorpha, are, nevertheless, much longer than those 

 of the Scincomorpha and the crossing in several representatives is complex 

 and also involves the m. pubo-ischio-femoralis externus. Moreover, according 

 to some data, parallel crossing may appear in the Gekkota and the Scinco- 

 morpha (difference in innervation - Sukhanov, 1957). 



"The usual speed of the Scincogekkonomorpha does not exceed 1.0 m/sec . 

 Maximum ground speed of a gecko escaping from an enemy is 1.2 m/sec. Tracks 

 left in the sand at that speed differ from ordinary ones in that the imprint 

 of the hindfoot is a round funnel. No imprints of individual toes remain. 

 The track of the forefoot retains imprints of toes. It is interesting that 

 this type of track is never seen under normal conditions even in the same 

 kind of gecko during its nocturnal activity, i.e., it is evident that the 

 ordinary demands of his movement are completely satisfied by a comparatively 

 slow speed (to 1.0 m/sec). Phrynocephalus mystaceus and P. reticulatus show 

 significantly greater variation in speeds in their normal "behavior." Tracks 

 with visible impressions of the toes correspond in these two forms to speed 

 not exceeding 1.0-1.2 m/sec. At higher speed the tracks, aside from a 

 natural increase in the stride, change their character sharply. Both fore- 

 and hindfeet now leave only simple funnels in the sand. Maximum noted speed 

 for P. mystaceus running from a enemy is 2.8 m/sec, for P. reticulatus 

 i+.O m/sec. The usual speed of rapid running in the first varies from 1.0 to 

 2.5 m/sec; in the second from 1.9 to 3.0 m/sec. Such speeds are often 

 observed under natural conditions. 



