Figure 6 . Two structural types of 

 the mm. extensores antebrachii 

 et carpi radial is 



A - Lacerta lepida: primitive condi- 

 tion observed in the entire Scinco- 

 gekkonomorphic line; muscle very 

 strongly developed, superficially 

 differentiated into several, heads; 

 some fibers - m. tractor radii - 

 supplied with flexor but not extensor 

 nerves. B - Phrynocephalus mystaceus; 

 muscle relatively weakly developed, no 

 differentiation, innervated only by 

 extensor nerves; this is observed in 

 all Iguanomorphia. an - m. anconeus, 

 b - m. biceps, br - m. brachialis 

 inferior, edl - m. extensor digitormn 

 communis, ear - mm. extensores ante- 

 brachii et carpi radialis , ecu - m. 

 extensor carpi ulnaris, far - m. 

 flexor antebrachii radialis, fcr - m. 

 flexor carpi radialis, sup - m. 

 supinator manus , trr - m. tractor 

 radii 



A number of primitive characters 

 relating the Gekkota and Scinco- 

 morpha is also observed in the muscu- 

 lature of hindlimbs : enlargement of 



the m. pubo-ischio-ttbialis (in 

 agamids, the muscle is much smaller, 

 particularly the first part which 

 disappears completely in Phryno- 

 cephalus); the origin of the inner 

 head of m. gastrocnemius arises only 

 from the tibia (in agamids, the 

 muscle also originates from the 

 femur; in gekkonids , on the other 

 hand, there is a distinct trend 

 toward the shortening of the inner 

 head of the gastrocnemius to its 

 complete reduction in the Caspian 

 gecko); the m. f 1 . tibialis internus 

 I is attached to both the tibia and 

 the femur . 



To supplement the aforemen- 

 tioned primitive characters shared 

 by the Gekkota and Scincomorpha, we 

 can add the primitive nature of the 

 throat muscles, osteoderm, unfused 

 medial skull elements (Camp, 1923), 

 lungs (Milani, 189^+), teeth, 

 digestive system, etc. A number of 

 these characters shared by Gekkota 

 and Scincomorpha remain poorly 

 studied, which makes it impossible 

 to determine the relative degree of 

 their evolutionary development. 

 These are: morphology of the m. fl. 

 tibialis internus I in comparison to 

 the m. fl. tibialis internus II; 

 size of the m. ilio-f ibularis ; rela- 

 tively weak development of the outer 

 head of the m. femoro-tibialis ; 

 origin of the accessory head of the 

 m. il. digitorum longus from the 

 fibula and, according to Camp, rela- 

 tively greater modification of the 

 postfrontal than the postorbital 

 bone. 



It is extremely important to 

 note that the Gekkota and Scinco- 

 morpha are related not only by 

 comparatively primitive character- 

 istics, but also by a niimber of 

 derived characteristics, which 



