98 MESSRS. MURIE AND MIVART ON THE 
abide by the Primatial type as wander from it. A tendency to deviate towards a not 
uncommon condition in Rodents and Carnivora is seen in the extra divisions of the 
pectoralis major; but a double layer is also frequently met with in Apes. 
The subclavius is tolerably human in character. The compound deltoid is a change 
from the higher and simpler condition to the constantly divided state in which it is 
found among Rodents, Carnivora, Ruminants, Marsupials, &c. A diminished teres 
minor, as in Lemurines, is met with in some Rodents. In almost all the lower Mammals, 
but only in some of the higher Primates, the rectus abdominis goes to the first rib, 
as is characteristic of the Lemuroids. In Man, Apes, and Lemurs, the serratus anticus 
and posticus are quite separate and but moderate-sized ; in some Rodents, and notably in 
Hyrax, they are continuous. A supracostal is the rule in the lower Mammalia; it is 
constantly met with in Lemuroids, but in the higher Apes it is not always present. 
The trapezius, the rhomboideus capitis, the levator clavicule, and the levator anguli 
scapulz, each and all, in development, relation, and attachment, are Ape-like, but not 
more so than in their compeers of lower grade. 
That the biceps humeri should be double in one portion of the group and single in 
the other is not readily to be explained; as regards affinities, conditions similar to both 
one and the other are found in higher and in lower groups. The lengthening of the 
brachialis anticus, and its non-embracement of the deltoid, are points indicating altera- 
tion in this muscle from the Simian, towards the purely rotating character which it 
bears in digging and swimming Mammals. 
The following muscles of the forearm are met with almost unaltered from Man and 
Apes :—the supinator longus and brevis, the extensor carpi ulnaris, the extensor secundi 
internodii pollicis, the pronator radii teres, the flexor carpi radialis, the palmaris longus, 
and the flexor carpi ulnaris. 
A divided or multiple extensor indicis, supplying tendons to the second and third, or 
even the fourth digit, occurs in higher Quadrumanous genera; Lemuroids repeat the 
character, which becomes less marked in lower Mammals, inasmuch as where the tendon 
is divided they chiefly go to the index and third digit. We meet with a numerous sub- 
division of the long extensors to the back of the hand in several Simian genera; and 
even in Man the extensor communis and minimi digiti often exhibit extra development 
of tendons, particularly the minimi digiti, which splits into branches going to the fourth 
and fifth digits. In the Lemuroids these characters are more constantly manifested, 
notably in the Aye-Aye, as we have shown. No part of the muscular system of Le- 
muroids exemplifies the gradual change of the Quadrumanous type into lower forms so 
markedly as do the long flexors of the palm and sole. In the manus the deep palmar 
tendons show much variety; but in all a short slip unites the flexor sublimis with the 
profundus: this has been demonstrated by Turner! and others to be not an unfrequent 
* «On Variability in Human Structure, with Illustrations from the flexor Muscles of the Fingers and Toes ” 
(Trans, Roy. Soe. Edinb. p. 180 et seq., fig. 2). 
