1&74-] MYOLOGY OF PHRYNOSOMA. 75 



Rectus abdominis has the same attachments as in L. belli Its 

 anterior portion is extremely thin, and is covered by a connective 

 tissue loaded with pigment-cells, which tissue also covers over the 

 sacro-lumbalis. 



It is a singular fact that there is not the slightest trace of a tra- 

 pezius in this lizard. 



Latissimus dorsi (figs. 2 & 3, L.D.) has an extraordinary arrange- 

 ment m this subject. It arises from the spines of the third and fourth 

 dorsal vertebrae, as a narrow muscular band which passes straight 

 across the back, over the posterior end of the scapula, until it reaches 

 the second dorsal rib, from which it takes a fresh and more extensive 

 origin ; the external fibres of this part of the muscle arise more 

 posteriorly, from the third, fourth, and fifth dorsal ribs. The whole 

 passes forward and ends in a flat tendon, which is inserted as usual 

 into the posterior surface of the humerus just behind the insertion 

 of the teres minor. It sends off a tendinous slip to join the inner 

 .head of the triceps -an arrangement which occurs also in Iguana 

 according to Mr. Mivart*. That part of the muscle which is situ- 

 ated between the scapula and the vertebral column was so closely 

 attached to the skin as to be with difficulty dissected from it 



Levator scapula (fig. 3, L.S.) arises from all that portion of the 

 suprascapula which is not occupied by the infraspinatus, with the 

 exception of a small portion situated at the junction of the dorsal 

 with the posterior border ; it passes forward to be inserted into the 

 transverse process of the axis. 



musde n o{ C LTeiu aliS reSembleS in ever ? res P ect the corresponding 



Sterno-coracoidalis externus (fig. 2, See.) arises from the inter- 

 nal surface of the coracoid, close to its lower or articular edge, and a 

 short distance from its anterior point, and passing backward is in- 

 serted into the outer angle of the sternum covered by the ligament 

 of the triceps. There are three serrati (fig. 2, S.J. 1, SJ 2 & 

 b.P.) precisely resembling those of L. belli. 



Supraspinal (fig. 1, S.S.) arises from the anterior margin of 

 and from the membrane covering the coracoid fenestra, and is inserted 

 into the anterior and outer point of the humerus in front of and 

 nearer the head of the bone than the infraspinatus 



Iufraspinatus (fig. 3, I. S.) arises from the central portion of the 

 outer surface of the scapula and suprascapula, and from the anterior 

 edge of that bone at the scapuloclavicular articulation ; it is inserted 

 into the outer edge of the humerus, just beyond the insertion of the 

 supraspinatus. 



Teres minor (fig. 3, Ts.M.) arises from the inner edge of the sea 

 pula at its point of junction with the coracoid ; it passes, beneath the 

 clavicle, and being, as usual, bound down by a tendon from the lone 

 head of the triceps, is inserted by muscular fibres into the humerus 

 commencing immediately within and just behind the anterior border 

 of the insertion of the infraspinatus, and extending obliquely 



* P. Z. S. 18(57, pp. 768, 780. 



