416 MR. A. SANDERS ON THE [June 9, 
Infraspinatus arises from the whole upper border of the scapula 
proper in a semicircular manner ; a few of the anterior fibres arise 
from the internal surface of the bone; the fibres converge, and are in- 
serted into the outside of the humerus beyond its head, dorsad of the 
insertion of deltoid, the interior part of the insertion being between the 
insertions of the two last muscles. This appears to correspond with 
the infraspinatus, by the same line of argument; if the coracoid 
points to the supraspinous fossa, the scapula would point to the 
infraspinous fossa. Mr, Mivart has called it the second part of the 
deltoid; but in this animal it has a separate insertion from that muscle. 
In addition the above arguments in favour of this view, I would draw 
attention to the arrangement of the insertions of these three muscles, 
which correspond in a striking manner with the arrangement of the 
three analogous muscles in mammals. 
Biceps is represented only by the coracoid head. It arises, broad 
and fleshy, from the anterior and inner half of the articular border of 
the coracoid, and from the surface of bone behind it. In passing 
over the shoulder-joint it developes a broad thin tendon ; beyond 
that point it again becomes fleshy, and in the arm it is thick and 
round ; it is inserted by a narrow tendon into the upper part of both 
radius and ulna, in conjunction with and on the distal side of the 
insertion of brachialis anticus. 
Coraco-brachialis brevis arises broad and fleshy dorsad of the last, 
from the posterior and inner half of the articular border of the cora- 
coid, and from the surface of bone outside it; passing close under the 
humero-scapular articulation, it is inserted into the inner side of the 
shaft of the humerus for nearly two-thirds of its length. 
Coraco-brachialislongus arises behind this, from the posterior angle 
of the coracoid bone, and, passing down inside the arm, it is inserted, 
narrow, into surface of bone immediately above the inner condyle of 
the humerus. 
Brachialis anticus arises from the whole length of the flexor surface 
of the humerus, commencing beyond the insertion of the supra- 
spinatus, and is inserted entirely into the proximal part of the ulna, 
together with part of the biceps-tendon. 
Trapezius consists of two portions, united together by a thin layer 
of muscular fibre. The anterior portion arises from the side of the 
complexus in conjunction with the neuro-mandibularis; the posterior 
part is attached to the general aponeurosis covering the dorsal mus- 
cles, extending back as far as the fourth dorsal vertebra: this part is 
inserted into the scapula immediately dorsad of the claviculo-scapular 
articulation ; the anterior part is inserted into the upper third of the 
clavicle. 
Latissimus dorsi arises from the spinous processes of the vertebree, 
from the seventh, or last but one, cervical to the fourteenth dorsal, 
both inclusive ; the anterior fibres are directed straight downwards, 
and the posterior obliquely downwards and forwards, to be inserted 
into the upper surface of the humerus, occupying one-third of its 
extent beyond the head. 
Triceps has four origins, the outer section arising by two heads, one 
