16 
supply the true pectoralis fibres send no filaments to this muscular 
mass, and the only other nerve in relation to it isa cutaneous branch 
of the N. supra-coracoideus (peculiar to Monotremes) which pierces 
the muscle, but, contra Westling, without supplying twigs to it. 
In Chlamydophorus* the deltoid is tripartite, with clavicular, acro- 
mial, and spinous sectors, as is the rule amongst the Hdentata. The 
clavicular deltoid may, however, be absent, as in Bradypus,t or it may 
be rather small, as in Chlamydophorus. In Bradypus the acromial and 
spinous portions are fused. 
In the Pacaf a clavicular deltoid is separated from an imperfectly 
divided acromio-spinous sector by a prolongation of the acromio- 
trachelien. A similar clavicular muscle-segment with imperfectly 
separated acromial and spinous portions was found by Mivart and 
Murie in Agouti and other rodents,$ but they consider the clavicular 
fibres to form part of the pectoralis major. 
In the Hedgehog]|| the deltoid is distinctly tripartite, the acromial 
and spinous portions being separated by the insertion of the 
acromio-trachelien. Leche,’ however, refers to it as single. 
In Talpa the scapular (spinous) portion is absent, according to 
Meckel** and Freeman.+t 
In Gymnuratt the clavicular portion is absent. 
In Chrysochloris the muscle arises from clavicle and metacromion. 
In the Cat, and apparently in the Carnivora generally, the clavicular 
deltoid is practically continuous with the cleido-trapezius forming the 
cephalohumeral muscle. Acromio- and spino-deltoids are also present, 
so that the muscle is here generally tripartite. 
M. latissimaus dorsi (figs. 1, 2, 6, and 7) resembles in general 
shape the muscle in the human subject. It is crossed by the 
spino-trapezius. 
Its origin is from the dorsal spines from the 3rd to the 12th 
(inclusive). There are no costal origins. Its fibres converge 
laterally and anteriorly towards the axilla, where, at the hinder 
border of the massive triceps, they ultimately form a thick pris- 
matic fleshy mass partly overlapped by the latter muscle. The 
latissimus is entirely destitue of a humeral insertion. Lying 
just posterior to the triceps, it enters the forearm, halfway down 
which the fleshy fibres end abruptly in the aponeurosis of the 
forearm, which is thus greatly strengthened, forming a dense 
layer on the surface of the flexor carpi ulnaris. The aponeurosis 
may be traced down to the manus. The insertion thus corres- 
ponds to one form of a dorso-epitrochlearis insertion, which is 
not otherwise present, and probably we ought to regard the two 
muscles as fused, or rather as unsegmented from one another. 
No trace of such a fusion in the form of a tendinous intersection 
was present. The muscle is quite unconnected with the teres 
major, but opposite the olecranon its fibres run just parallel to 
* xxvii., page 243. +xxxii., page 56. tvi. PL, 249, fig. 2, and PL, 251, 
fig. 1. §xL, page 398. ||vi. Pl., 75 and 76. {i xxvi., page 792. ** xxxviil., 
page 496. +txi., page 213. {xxvi., page 792. 
