In favor of the actuality of the motion observed in connective-tissue preparations of the 

 skull is the fact that analogous movements on a much larger scale are more noticeable in the head 

 of a freshly killed animal with fully preserved muscles, ligatures, etc., than in the connective 

 tissues of preparations. Thus, the length of the skull of Varanus qriseus from 



--Fig. 6— 



the end of the snout to the occipital condyle, varies accordingly: as much as 8.57* °f median 

 skull length (71-3 mm ) during protraction and retraction in "fresh" heads, in three wet connective- 

 tissue preparations of skulls of same size — on the average, only 2.45? (2.3 - 2.7). 



For proof of active movement in the kinetic skull, examination of living lizards and analysis 

 of the lines of force arising in the cranium during the contraction of cranial muscles is necessary. 

 Direct examination of skull kinesis in lizards is difficult due to their great rapidity 



--p. 1405— 



which i 

 to whic 

 with th 

 retract 

 protrac 

 also 



ica and Lacerta aq il i s gave results that were 

 y these lizards repeatedly rotate the head 

 the kinetic movements of the skull are hard 

 the desired for the actual effect. The 

 selection of living forms. Both Lacerta and 

 they do not have movement within the palatine 

 n lizards of the second group. Thus in Lacerta , 

 y segment are around the metakinetic axis, 

 and Aqama has a very broad and low skull, thanks 

 g a slight lateral inclination. Frazzetta, 

 rey by Gerrhonot us coeruleus . He noted that 

 nd compression of the lizard's jaws, while 

 uth. Frazzetta's observations were confirmed 

 lot icus. 



Frazzetta made a graphic analysis of the lines of force arising du 

 the jaw muscles in the cranium of Varanus . This analysis seems fundame 

 what superficial, since Frazzetta did not study the jaw musculature of 

 did not try to assign a role to all the muscular parts. Protractors of 

 lizards appear in M. protractor pterygoidei and M. levator pterygoidei; 

 the fibers of the large M. adductor mandibulae externus (but never M. p 

 Frazzetta's assertions). Various parts of the M. adductor mandibulae e 

 different roles in the movements of the cranial mechanism: a large par 

 muscle have a retractive effect, some are neutral in relationship to th 

 some manifest themselves as protractors. The summary effect of contrac 

 mandibulae externus is retraction. Our studies of the jaw musculature 

 parts of M. adductor mandibulae externus, accepted in the works of Lakj 

 I. Poglayen-Neuwall (1954), Oelrich (l?56) and others, do not correspon 

 and topographic units of the muscles. Furthermore, he (Frazzetta?) doe 

 identifying these parts in various forms in the order Sauria and, moreo 

 same names in other reptiles. The scope of this article, unfortunately 

 add here a detailed analysis of the structure and function of lizard ja 

 this in future publications. 



ring the contraction of 

 ntally accurate, but some- 

 the lizard in detail, and 

 the jaw mechanism in 

 retractors are primarily 

 terygoideus, despite 

 xternus play completely 

 t of the fibers of the 

 e cranial mechanism and 

 t i on of M. adductor 

 of lizards showed that 

 er (1926), Lubosch (1933), 

 d with the functional 

 s not succeed well in 

 ver, with parts with the 

 , does not allow us to 

 w muscles; we hope to do 



In his analysis of the functions 

 important error: according to his opinion, 

 of the jaws on the prey. Actually, this mu 

 of the cranial mechanism. Its force is app 

 and downward posteriorly of the jaw articul 

 pterygoideus does not change in conformity 

 with kinesis are in no way affected by the 

 Fig. 11 in Frazzetta's paper). M. pterygoi 

 ditions: (l) flexibility of the palatine a 

 the pterygoids); (2) the origin of M. ptery 

 from the palatine bone or the bones of the 

 The second condition is not fulfilled in 1 

 the maxillary segment lies in the transfer 

 M. adductor mandibulae externus from the 1 

 1936). 



e cran 

 M. pt 

 scle i 

 lied t 

 at ion. 

 to th 

 length 

 deus m 

 rch (a 

 go i deu 

 snout, 

 zards. 

 of the 

 wer ja 



mecha 

 goideu 

 i zards 

 he pte 

 y such 

 ranial 



M. pt 

 t be a 

 east i 

 n terio 

 *cf. G 

 he rol 

 tract i 

 th 



m of 

 s a 



nei 

 i ds 

 tach 

 chan 

 goid 

 trac 

 he j 

 f th 

 og ic 

 f M 

 fore 



palat i 



1 i za 

 retra 

 ther 



and 



ent 



sm. 

 eus 

 tor w 

 unctu 

 e h i n 

 hesk i 



pter 

 e co 

 e ar 



rds, 

 ctor 

 a re 

 to t 

 , th 

 The 

 Fig. 

 ith 

 re 

 ge*l 

 i SI 

 ygoi 



7; 



fulf 

 f th 

 ine 

 onar 

 deus 



h (for b 



zetta made one 

 least in the closing 

 or or protractor 

 wer jaw, forward 

 traction of M. 

 ments associated 

 t corresponds to 

 llment of two con- 



palat i ne bone and 

 f the palatine arch 

 Sofiano, p. 223). 

 i n retract i on of 



the contract i on of 

 rds - see Mar i nell i , 



-p. 1406-- 



