162 DR. R. W. SHUFELDT ON [Apr. 1, 



described one, and in its characters it almost agrees with the same 

 muscle in TAolepis, as described for us by Sanders. Arising from the 

 summit of the interclavicle and the adjacent fascia, it takes a course 

 directly np the middle of the neck, to become inserted into the basi- 

 hyal and for a limited distance on the adjacent thyro-hyal, on their 

 posterior margins. This muscle is almost in contact with the 

 fellow of the opposite side for its entire length. 



14. The Sterno-hyoideus profundus is situated deep to the two 

 last-mentioned muscles, it taking origin from the interclavicle, the 

 corresponding clavicle for nearly its entire length, and from the deep 

 fascia of the neck adjacent to these parts. From this origin its 

 fibres are directed upwards, forwards, and outwards, to finally insert 

 themselves along the hinder border of the thyro-hyal of the same 

 side, from its tip inwardly to the point of insertion of the sterno- 

 hyoideus. At the postero-mesial point of origin this muscle and 

 the fellow of the opposite side are in contact. 



Muscles of the Shoulder-Girdle and the Upper Extremity . 



15. The Sterno-mastoideus in this lizard is a strong, broad, and 

 flat muscle, which arises from the summit of the interclavicle at its 

 external aspect, also from the adjacent fascia as far back as the 

 shoulder-joint. Passing obliquely upwards, forwards, and outwards, 

 it is inserted into the outer end of the squamosal of the corre- 

 sponding side. At its insertion it is covered by the neuro- 

 mandibularis. Posterior to this the sterno-mastoideus is attached 

 to the superficial fascia overlying the deeper muscles of the back of 

 the neck, as far back as the third cervical vertebra. In this 

 locality the muscle becomes very thin. The anterior and posterior 

 portions of this muscle are somewhat individualized, more especially 

 the dorsal moiety of the muscle, where the cranial and cervical 

 insertional parts are quite distinct. 



16. Trapezius. — This muscle is comparatively feebly developed 

 in Heloderma, being subtriangular in form, and overlapping behind 

 the anterior portion of the latissimus dorsi. It arises as a thin 

 sheet of tendon from the fascia that springs from the cervico-dorsal 

 vertebrse at the summits of their neural spines, from about the last 

 few cervical vertebrae, to include the first two dorsals. The fibres, 

 forming a thin muscular plane, converge as tliey pass down towards 

 the shoulder-joint, where they again become tendinous, and are 

 finally inserted at the anterior portion of the outer aspect of the 

 suprascapular of the same side, to the fascia below and posterior to 

 this, and more anteriorly to the outer extremity of the corre- 

 sponding clavicle. 



17. Latissimus dorsi is a much better developed muscle than the 

 last described, being a strong, flat, triangular fasciculus of rather 

 coarse muscular fibres, which arise for the most part from the 

 aponeurosis of the dorsum that is attached to the neural spines of 

 the tenth to the twenty- first vertebrte inclusive, being adherent to the 

 fascia covering the deeper muscles for some little distance outwards 



[16] 



