29 
interscapular ligament. Its tendon of insertion is largely united with 
the latissimus. 
In Chrysochloris* it arises as a bicipital muscle, but the heads unite 
with each other and with the latissimus towards their insertion. 
M. teres minor is entirely absent. 
Amongst Marsupials it is absent as a rule, according to Meckel.+ 
It is present, however, in Cuscus, and Thylacine, Koala? occasionally,s 
Dasyuwrus viverrinus, and Phalangista vulpina,|| though in the latter 
Macalister could not separate it from the infraspinatus. 
Cuvier and Laurillard figure it in Mucropus giganteus.1 
In Phascolomys and Sarcophilus** Macalister found it represented by 
a fibrous band merely. 
It is said to be entirely absent in the Monotremata.t+ I cannot, 
however, think that sufficient consideration has been given to the 
claims of the small muscle, which Westling}{} names “subscapularis 
accessorius’’ in Echidna, to represent a teres minor. I have already 
pointed out that it is the homologue of this muscle in Ornithorhynchus 
which Leche erroneously describes as the subscapularis in that animal. 
In point of fact there is no essential difference between Ornithorhynchus 
and Hehidna in respect of the arrangement of the muscles of this 
region For details of this arrangement [ must refer to Dr. McKay’s 
forthcoming account of the myology of the region in the twoforms. But 
I have satisfied myself from that gentleman’s dissections that the little 
muscle in question does not correspond with any other typical muscle 
of the region if we except the teres minor. It is mentioned by Mivart 
in Echidna§$§ as a “ small delicate muscle,”’ but he attaches no name to 
it, and the only view regarding it of which I am aware is Westling 
and Leche’s, according to which it is, in the Echidna, a subscapularis 
accessorius, and in the Ornithorhynchus, the subscapularis itself. It is 
indeed possible that it is a “subscapularis accessorius.”’ It receives 
its nerve supply from the Nervus axillaris like the subscapularis; but 
the twig of supply comes off the N. axillaris between the subscapular 
branch and that for the scapular deltoid, in fact nearer to the latter, 
with which nerve it is connected by a filament of communication ; so 
that the mode of innervation is at least as consistent with the 
homology to a teres minor. But further, its position seems to 
negative its attinity to subscapularis, for the scapular head of the 
triceps passes between the two, so that the small muscle is con- 
tiguous on the other hand to the infraspinatus. A muscle thus 
arising from the scapula close to the glenoid cavity, intercalated 
between infraspinatus on the one hand and long or scapular 
head of the triceps on the other, may surely well enough be teres 
minor, especially as its innervation is quite conformable to that view 
of its homology. It is indeed only with regard to its insertion that 
any serious difficulty arises, for in both Echidna and Ornithorhynchus 
the muscle in question is inserted close to the subscapularis, though 
quite distinct from it, into the dorsal face of the expanded ulnar 
*xxvi., page 796. txxxvili., page 513. tiv., page 8. §lxxii., page 
227, and xxvili., page 130. ||xxxvi., page 117. ‘vi. Pl., page 177-8. 
** xxix., page 159. tfxxvi., page 795, and xxxix., page 384. +t lxii., 
page 15. §§$ xxxix., page 385. 
