15S DR. R. W. SHUFELDT ON [Apr. 1, 



III. Of the Myology. 



To assist nie ia the demonstration of the muscles of this lizard 1 

 have at my hand an excellent paper entitled " Notes on the Myology 

 of Liolepls belli," by Alfred Sanders (P. Z. S. 1872, p. 154)'; 

 also one entitled " Notes on tlie Myology of the Phnjnosoma 

 coronatum," by the same author (P. Z. S. 1874, p. 71) ; also the 

 admirable memoir, "On the 'Myology oi Chamceleon parsonii," by 

 Professor St. George Mivart (P. Z. S. "1870. p. 850); and finally the 

 more generalized contribution to the study of the muscles in Lizards 

 jiresented us by Prof. C. K. Hoffmann in Broun's ' Thier-Reichs ' 

 (45). With these I must likewise mention the studies of Professor 

 Mirart upon the Iguana (P. Z. S. 1867) ; and other works on the 

 muscles of reptiles by the same distinguished author. As to the 

 names I here bestow upon the muscles of the Heloderm, I can say 

 with Sanders, who remarked in his paper on the myology of Liolepis, 

 that "With regard to the nomenclature, it must be regarded as 

 merely fl tentative expression of opinion, liable to be changed at any 

 time on the demonstration of error." It is a long day yet before we 

 can say in truth that our knowledge of the myology of reptiles is iu 

 any way complete, and a great many forms still remain to be worked 

 out. 



Muscles of the Head. 



1. Mylo-hyoideus uaterio7\ — We find in the present subject this 

 muscle to be but feebly developed ; it arises, on either side, from 

 the inner aspect of the lower border of the ramus of the jaw, for 

 about its anterior moiety, and as far forward as the symphysis. 

 Mesially, it indistinguishably blends with its fellow of the opposite 

 side, making no median raphe. Postero-laterally it faintly overlaps 

 the mylo-hyoideus posterior, while at the middle of the throat it 

 almost seems to blend with that muscle : and this delicate, super- 

 ficial j)lain of transversely disposed muscular fibres overlays a number 

 of the group of the more deeply situated and true hyoidean 

 muscles. 



2. Mylo-hyoideus posterior is a far better developed nmscle than 

 the one 1 have just described, and apart from its greater size it 

 differs from it in that it exhibits a fairly well-developed medio- 

 tcndinous raphe for nearly its entire length. Into this the niuscle 

 of either side merges. Springing from the occiput and the dense 

 fascia at the antero-superior part of the neck, from the mandibular 

 suspensorium, as well as from the inner aspect of the posterior moiety 

 of the mandible itself, the posterior mylo-hyoid sends its fibres, for the 

 most part, transversely to the middle line of the throat, where they 

 blend with the delicate, longitudinal, raphenous line in a manner 

 wliich 1 have already indicated. The posterior border of this 

 muscle is well-defined and thickened : it crosses the throat just 

 anterior to the region of the chest ; while laterally the hinder 

 margm of an aural apertuic is formed by its free muscular edge. 

 Anteriorly it is very thin where it meets the anterior mylo-hyoid iu 



