The m. trapezius of gekkonids and scincids is not separated from the m. 

 episterno-cleido-mastoideus (Fig. 3, A) nor divided into two parts, which is 

 typical of the agamids (Fig. 3, D) ( "acromiotrapezius ," attached to the 

 acromial part of the scapula, and "clavotrapezius ," ending at the clavicle). 

 In Iguanomorpha, the trapezius muscles (Fig. 3, D, E, F) are separate from 

 the m. episterno-cleido-mastoideus and show an obvious tendency toward reduc- 

 tion, even to complete loss of the "clavotrapezius" (Fig, 3, F). In the 

 lacertids, on the other hand, the m. episterno-cleido-mastoideus is very 

 weakly divided; if the m. trapezius is reduced, it is at the expense of the 

 posterior acromial part (Fig. 3, B, C). Thus, divergent trends are seen in 

 the development of the m. trapezius in the lacertids and agamids. 



The changes occurring in the m. anconeus are interesting. In the 

 scincids and lacertids (Fig. k. A) the muscle has a long "scapular" head 

 closely connected at its origin with lig. scapulo-hiomeralis lateralis and lig. 

 axillaris. In the gekkonids, the lig. axillaris is reduced, but the 

 primitive scapular head of the m. anconeus is preserved (see Fig. 7, C). In 

 all Iguanomorpha (Fig. h, B) there are two long heads: scapular and cora- 

 coid.5 It is possible that the heads were formed by the divergence of fibers 

 of the primitive "scapiilar" head by lig. axillaris. The scapular head, still 

 retaining as its origin the primitive connection with lig. scapulo-humeralis 

 lateralis, loses it in the course of evolution of Iguanomorpha. Thus, the 

 morphological trends of the m. anconeus of the Gekkota and Iguanomorpha are 

 contradi ctory . 



The m. supracoracoideus of gekkonids, scincids, and lacertids is 

 relatively small; the site of its origin is limited to the anterior edge 

 of the bony coracoid (Fig. 5, A). A different muscle is seen in the 

 Iguanomorpha. Agama has a much larger muscle: its origin occupies not 

 only the bony part of the coracoid, but also its cartilaginous part, the 

 so-called "epicoracoideum," circumscribing the coraco-scapular fenestra and 

 even a small part of the scapula (Fig. 5, B). In Phrynocephalus , (Fig. 5, 

 C), the cartilaginous "epicoracoideiim" is reduced. As a result, the muscle 

 is divided into two parts - a coracoid part similar in volume and form to 

 the m. supracoracoideus of gekkonids and scincids and a scapular part of 

 increased size; in comparison with Agama, its fibers occupy a larger area 



In the relatively primitive Gekko Japonicus (Sanders, I870) a 

 remnant of this connection is evidently still retained in the form of a 

 tendon leading from the posterior angle of the coracoid to the m. anconeus. 

 But it does not join with the lig. sterno-scapularis internum. 



-'The study of this taxon led to the incorrect idea that the primitive 

 state of the m. anconeus of all reptiles is quadricipital : two long and 

 two short heads (Romer, 1922). 



