24 
inserted partly into the scapular end of the clavicle and into the spine 
of the scapula and the fascia over the supraspinatus muscle. (Cf. 
also Rolleston’s detailed description of the double sterno-scapular 
muscle in the Guinea Pig, the smaller of which he also regards as 
homologous to the subclavius.*) 
Windle just mentionst the subclavius as “a strong muscle” in 
Erethizon epixanthus, but the same author{ has described in detail the 
condition in the Rabbit, and concludes that the deep sterno-scapular 
slip there present represents probably part at least of the subclavius. 
In Talpa Freeman§ refers to the large subclavius arising from pro- 
sternum and first rib, and dividing into two parts to be inserted (a) into 
the outer third of the dorsal margin of the coraco-clavicle (b) into the 
short acromion and the acromio-clavicular ligament. 
Cuvier and Laurillard|| figure a subclavius in the Hedgehog whose 
origin very closely resembles in its relations that of Notoryctes; its 
insertion? appears to be clavicular and acromial. 
Leche** notes a subclavius as present in Condylwra, Solenodon and 
Gymnura. : 
A true subclavius seems hardly to be represented amongst the Car- 
nwwora, though sterno-scapular slips are found, e.g. in Dog and Hyzna**, 
and in Procyon cancrivorust + and others. Probably most of these slips 
are of the nature not of subclavius, but of “ pectoralis minimus,” or, 
as Windle names them, “ deep manubrial” slips of the pectoral group 
(see this author’s discussion on the subject of sterno-scapular slips).{{ 
M. pectoralis (figs. 3, 6 and 7, p.a., p.b., and p.c.). The pectoralis 
system of fibres consists of a large mass of considerable thickness 
and of the ordinary triangular or fan-like shape. It is separable 
into three sectors, which we have distinguished as A, B and C, 
with which will also be described the humeral portion of the 
panniculus carnosus. 
In one specimen the sternal rostrum was specially large, and 
was perforated by a large oval fenestra (fig. 21, fen.) filled up 
with fibrous membrane from either side of which fibres of oppo- 
site pectoral muscles took origin. 
M. pectoralis A (figs. 3, 6 and 7, p.a.) arises from the rostrum 
and body of the presternum and from the sternal end of the 
clavicular arch, the latter fibres being overlapped at their origin 
by the sternal attachment of the sterno-mastoid muscle. Its 
deepest fibres further arise from the broad, flat and expanded 
inner end of the first costal arch. From this origin the fibres 
extend outwards, chiefly transversely, but the hinder fibres more 
obliquely, towards the humerus, and they end in a partly fleshy 
insertion which is attached, along with that of the next sector, 
into the distal of the two tuberous elevations of the “deltoid 
ridge,” which is thus a deltopectoral tuberosity. 
*li., page 611-2. tlxv., page 128. {1xvii., page 354. §xi., page 211. 
vi. Pl. °75, fig. 2h. “Wvi. Pl., 76, fig. 2. ** xxvi.j page 764. Tria, 
page 82. tt lxvii., page 352, e¢ seq. 
