386 MR. ST. G. MIVART ON THE ANATOMY OF ECHIDNA HYSTRIX. 
the epicoracoid. It is inserted into the radius in part, but also into the ulna as far back 
as the coronoid process, being intimately connected posteriorly with the insertion of the 
brachialis anticus. This insertion into both radius and ulna takes place in the Pig!, 
and, according to Meckel?, it is inserted, either wholly or in part, into the ulna in many 
animals. 
Brachialis anticus.—This is a very small and delicate muscle, closely embraced ex- 
ternally by the supinator longus. It arises from the radial side of the shaft of the 
humerus, its origin extending from the lowest point of the insertion of the deltoid up 
to the tendon of origin of the external head of the ériceps. It is inserted into the part 
of the ulna representing the coronoid process, the anterior margin of its tendon being 
closely united with the posterior margin of that of the biceps. 
Triceps (Plate LII. fig. 1, r).—This is an enormously powerful muscle, and consists 
of two main portions, one arising from the scapula, the other from the humerus. 
The scapular portion has a very elongated origin, extending from the humeral end of 
the axillary margin of the scapula, obliquely upwards and forwards, to near the anterior 
vertebral angle; it has a strong tendon at its lowest part, which passes inwards beneath 
the subscapularis. It is inserted by muscular fibres into the whole breadth of the 
oleeranon. 
The humeral portion covers the entire posterior surface of the shaft of the humerus, 
whence alone it takes its origin, with the exception of a small and more or less distinet 
slip, which arises by a marked tendon from beneath the posterior part of the greater 
tuberosity, immediately external to the origin of the supinator longus. It is inserted in 
common with the scapular portion; but it forms an arch (extending from the inner con- 
dyle to the olecranon), beneath which pass the inferior profunda artery and the ulnar 
and median nerves. | ! 
The musculo-spiral nerve passes between the tendon above mentioned and the rest of 
the humeral part of the triceps. | 
The supinator longus (?) is larger than the brachialis anticus. It arises from the poste- 
rior part of the radial surface of the humerus, its origin extending up beneath the small 
tendon of origin of the external part of the humeral portion of the triceps. Passing 
downwards, it becomes connected with the outer surface of the brachialis anticus, and 18 
inserted into the anterior surface of the radius, on a line with and just above the inser- 
tion of the pronator teres, and just on the radial side of the insertion of the biceps, and on 
the ulnar side of the insertion of the supinator brevis. 
The radial nerve passes down on the outside of this muscle, which is inserted inter 
nally to the supinator brevis. 
The median and ulnar nerves, together with what appears to be the inferior profunda 
artery, pass round outside the conjoined insertion of the second part of the latissimus 
dorsi anddorso-epitrochlear. The median nerve, as in theOrnithorhynchus’, passes through 
' Meckel, * Anat. Comp." vol. vi. p. 286; and Prof. Huxley in his Hunterian course for 1865. 
* Loc. cit. p. 283. 
* Meckel, loc. cit. p. 34 ; Owen, loc. cit. p. 387. 
