of the scapula and part of the clavicle and extends between these bones to 

 the inner side of the suprascapular cartilage." It is still difficult to 

 decide in which (Gekkota, Scincomorpha , or Agamidae) the m. supracoracoideus 

 show primitive condition. If the agamid condition is primitive, then we see 

 contradictory trends in the direction of muscle evolution in the advanced 

 Agamidae and Scincogekkonomorpha'^ : in the first - separation of the muscle 

 into two parts and formation of m. supracoracoideus accessorius, in the 

 second - retention of an unicipital muscle. If the condition in the gekkonids , 

 scincids, and lacertids is more primitive, then we must speak of its retention 

 in the entire scincogekkonomorphic evolutionary line and continual differ- 

 entiation in the Iguanomorpha. 



Tlie m. biceps of the gekkonids and scincids has only a fleshy origin 

 ("proximal muscle belly"). In some advanced Scincomorpha (Lacerta, Ameiva, 

 Tupinambis - Fiirbringer, I876, 1900 ) there is slight reduction of the 

 proximal belly - there is a narrow, tendonous part along its edge. The 

 complete reduction of the proximal belly of m. biceps occurs in the advanced 

 Iguanomorpha (there are numerous intermediate stages - Camp, 1923). Thus, 

 again we see parallel development in the advanced Scincomorpha and Iguano- 

 morpha but reduction begins much earlier in the latter group. 



The presence of a primitive radial complex of forearm extensors (mm. 

 extensores antebrachii et carpi radialis), such as in tortoises (Fig. 6, A) 

 is very typical of the gekkonids, scincids, and lacertids. In this muscle 

 complex some fibers ("m. tractor radii" - Haines, 1939) are supplied by a 

 branch of the flexor nerve (n. brachialis longus inferior), perforating the 

 m. biceps and m. brachialis. A foramen ectepicondyloideus (Ribbing, 1907, 

 1938) for the extensor nerve, n. radialis occurs in all these families 

 supplying the greater part of the extensor radial complex. In all Iguano- 

 morpha (Fig. 6, B) this muscle complex is greatly reduced; the "m. tractor 

 radii" also loses its flexor innervation. The foramen ectepicondyloideus 

 also disappears. 



The flexor ulnar complex of the forearm is greatly reduced in the Iguano- 

 morpha: there is a progressive reduction of m. fl. antebrachii ulnaris (still 

 observed in two iguanid genera Ctenosaiira and Sceloporus - Straus, 19^2) to 

 its complete loss in advanced forms (Agama, Phyrnocephalus ) . In the entire 

 Scincogekkonomorphic line, this muscle evidently does not undergo reduction. 

 Thus, a distinct trend can be noted in the Iguanomorpha toward enlargement of 

 the antebrachial musculature. 



We called the scapular part of the m. supracoracoideus of the advanced 

 agamids the m. supracoracoideus accessorius. 



Scmcogekkonomorpha here refers to a taxon at a division level combining 

 Gekkota and Scincomorpha. For contrast, we suggest the name Iguanomorpha for 

 the group including Iguanidae, Agamidae and Chamaeleontidae . 



o 



A difference in times of reduction can also be assumed. 



