PROFESSOR WOOD ON THE NECK- AND SHOULDER-MUSCLES. 
105 
the acromion process and cicromio-clavicular ligament, where it was still more distinctly 
separated from the subclavius. In the same animal Mr. Hill found, as I have myself 
subsequently also done, a remarkable development of the sterno-clavicular muscle, as a 
large triangular mass of muscle arising from the front half of the sternum, and inserted 
into the stunted but strong clavicle close to the origin of the deltoid. The same author 
also mentions the presence of this muscle in the Bats. 
A sterno-scapular muscle is described by Mr. Galton in the Dasypus sexcinctus under 
the head of subclavius , arising from the first rib, and inserted by a fiat tendon along the 
whole extent of the upper edge of the strong acromion process, and continuous with the 
supraspinous fascia. He refers to its similarity to the sterno-scapular muscle described 
by Mivart and Murie in the Agouti (Trans. Linn. Soc. vol. xxvi. p. 528). He also 
found the subclavius inserted into the acromion process of the scapula in the Two-toed 
Sloth. In the Cape Anteater, Humphry describes the subclavius as a large muscle arising 
from the first and second rib-cartilage and adjacent part of the sternum beneath the 
pectorals-, it is attached by a few fibres to the clavicle, but the major part passes 
beneath that bone over to the coracoid and its ligaments to be inserted into the supra- 
spinatus fascia, as well as to the margin of the acromion process (op. cit. p. 297, and 
plate 4). Galtox found, in the same animal, a sesamoid bone at the insertion of the 
muscle, just under the acromio-clavicuHr joint (op. cit . p. 572). 
In the Carnivora the homologies of the sterno-scapular muscle are but little decided. 
In the Weasel a deeper set of the pectoral muscular bundles, arising from the manubrium, 
pass upwards and outwards over the tuberosity of the humerus, and are continuous with 
a muscular layer lying upon the supraspinatus, and attached with it to the upper 
border of the scapula (Plate XI. fig. 24, i). In the Dog also, a few of the fibres of the 
pectoralis are differentiated and connected with the supraspinatus. In Cuvier and 
Laurillard’s plates of the Lion, it seems to be -represented by the muscle marked J, 
and in that of the Panther marked J-j-2. In the Hyaena it is very large, attached, on 
the one hand, to the sternum and first rib-cartilage, and on the other to the upper 
border of the scapula (j-\-). It seems also to be present in the Genette. In the Rodents 
it is better marked, blended, however, more or less, with the subclavius , the scapulo- 
clavicular , and the sterno-clavicular muscles. I have found it very large in the Rabbit 
(Plate X. fig. 16, B, i i), arranged in two thick bundles, an upper (i) and a lower (i r ) 
passing from the front of the manubrium sterni and suprasternal process, and continued 
uninterruptedly under the clavicle, forming a thick sheet of muscle upon the supra- 
spinatus (q) to be inserted into the upper border of the scapula. Connected with it and 
covering its upper half above the clavicle is a layer of fibres (A, k), reaching only from 
the scapular spine to the clavicle (x), into the upper border of which they are inserted. 
This layer, more or less separable from the deeper or true sterno-scapular fibres, I have 
considered to represent the scapulo-clavicular muscle, which becomes a more distinct 
muscle in its congeners, the Guinea-pig and Norway Rat (Plate X. fig. 17, A & B, k, and 
Plate XI. fig. 25, k). On the opposite or lower border of the clavicle are attached the 
MDCCCLXX. P 
