274 ZAGLOSSUS. 
for the Echidna, arising by tendinous fibers from the median edge of the ulna 
just distal to the sigmoid notch and by fibers from the ligament between ulna 
and radius. Proximally the muscle is closely applied to the supinator, and then 
passes as a stout flattened tendon across the tendons of the extensores carprt 
radialis longus et brevis to insert on the radial side of the first metacarpal. 
The pronator teres (Plate 1, fig. 2, pt; fig. 3, pt) is strongly developed. 
It has origin by a flat tendon from the medial edge of the internal epicondylus 
of the humerus and is partly covered by the flexor carpi radialis. The muscle 
thickens in the middle, and becomes somewhat triangular in section. Distally 
it flattens again and inserts by muscular fibers along the medial edge of the 
radius from the insertion of the biceps to the epiphysis. 
The flexor carpi radialis (Plate 1, fig. 3, fr) is a large, radially compressed 
muscle, arising from the anterior edge of the internal epicondylus of the humerus 
slightly external to the origin of the pronator teres, whose base it slightly over- 
laps. It passes into a stout tendon at the beginning of the terminal third of the 
fore arm and inserts into the proximal end of the second metacarpal, ventrally, 
and by a continuation of the tendinous portion it is likewise united with the 
first metacarpal. The condition is essentially the same as in the Kchidna. 
The palmaris longus is lacking, at least as a separate muscle. Mivart 
considers that it is fused in the Echidna with the flexor profundus digitorum. 
The flexor carpi ulnaris (Plate 1, fig. 3, fw) is from two heads as usual:— 
(1) for nearly one third the length of the ulna from the olecranon along its 
ectal edge, (2) by a smaller flatter muscle arising at the ectal corner of the 
epicondyle of the humerus, where it partly overlies the most exterior head of 
the profundus. The ulnar head is the larger and the tendons of the two unite 
just proximal to the distal head of the ulna and insert as usual into the pisiform 
bone. Proximally the second head is united by a few fleshy fibers to the base 
of the profundus. 
The flexor sublimis digitorum is lacking as a separate muscle. 
The flexor profundus digitorum (Plate 1, fig. 1, p; fig. 3, p) is enormously 
developed and arises from four heads:— (1) an ulnar head, from the proximal 
two thirds of the inferior surface of the ulna and from fascia between the radius 
and ulna; (2) from the angle of the internal epicondylus of the humerus where 
it is partly covered by the second head of flexor carpi ulnaris; (3) a thick portion 
arising also from the internal epicondylus, just medial to the second portion 
of the profundus, to which it is intimately connected by muscular and tendinous 
fibers; (4) a deep lying slender and spindle-shaped muscle quite distinct from 
