OCR Text |
Show 158 DR. R. W. SHUFELDT ON L^Pr< *» III. OF THE MYOLOGY. To assist me in the demonstration of the muscles of this lizard I have at m y hand an excellent paper entitled " Notes on the Myology of Liolepis belli," by Alfred Sanders (P. Z. S. 1872, p. 154); also one entitled " Notes on the Myology of the Phrynosoma coronatum," by the same author (P. Z. S. 1874, p. 71); also the admirable memoir, " O n the Myology of Chamceleon par sonii," 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 presented us by Prof. C. K. Hoffmann in Bronn's ' Thier-Reichs' (45). With these I must likewise mention the studies of Professor Mivart upon the Lguana (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 a 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 in any way complete, and a great many forms still remain to be worked out. Muscles of the Head. 1. Mylo-hyoideus anterior.-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, superficial plain 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 muscle than the one I have just described, and apart from its greater size it differs from it in that it exhibits a fairly well-developed medio-tendinous raphe for nearly its entire length. Into this the muscle 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 which 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 margin of an aural apertuie is formed by its free muscular edge. Anteriorly it is very thin where it meets the anterior mylo-hyoid in |