PROFESSOR WOOD ON THE NECK- AND SHOULDER-MUSCLES. 
101 
portion of the cephalo-humeral muscle, the lower part of which is formed by the muscles 
which form, in Man, the clavicular fibres of the deltoid and pectoralis major. In some, 
as in the Cat, this compound muscle is inserted as far down as the coronoid process of 
the ulna by longitudinal fusion with the brachialis anticus ; but in most, as in the 
Dog, Badger and Weasel, and in the Ilabbit and Guinea-pig, it is inserted into the 
humerus close below the pectoralis major. It will be seen, then, that I find the liomo- 
logue of the cleido-occipital in the muscle which Meckel and Cuvier described as a 
second cleido-mastoid in the Insectivora and semiclaviculate Bodents, as well as in that 
which they have described in the Carnivora as the cervical portion of the trapezius , or 
the trapezius clavicularis (the clavo-cucullaris of Steauss-Durckiieim). The intervention 
of the acromial insertion of the acromio-trachelien between the fibres of this muscle and 
the trapezius proper, before alluded to, and the gradual way in which it excludes the 
trapezius from the occipital bone in the lower Apes and Monkeys, its relation to the 
latter muscle at the occiput, and the occasional blending at their adjacent borders as 
an abnormal human variety, are all circumstances which favour this view, which has also 
the merit of simplifying the perplexing homologies of the cephalic portion of the com- 
pound cepkalo-humeral muscle, and explaining, more fully than before, the abnormal 
human varieties so frequently found in connexion with the side of the neck and shoulder. 
The identity of these homologues is well seen in the transitional forms found in the 
Insectivora and in the claviculate and semiclaviculate Bodents, as I have shown in the 
case of the Babbit and Hedgehog. 
In many of the Carnivora the cephalic and cervical portion of the compound cephalo- 
Tiumeral muscle is enormously developed, encroaching upon and excluding the trapezius , 
not only from the occiput, but also from the neck- vertebrae (see Plate XI. fig. 23, c ). 
Forming a broad sheet of muscle, with the fibres directed downwards and backwards, its 
deeper fibres are, in the Cat, inserted upon a cartilaginous rod representing the clavicle 
( x ). Into the deeper surface of this are also inserted the fibres of the distinct cleido- 
mastoid element ( l> ) ; the superficial fibres are, however, continued over the surface of 
this rod uninterruptedly into the arm by longitudinal fusion with the clavicular fibres of the 
pectoralis major (as Strauss-Dukckheim thinks), and blending finally with the superficial 
fibres of the brachialis anticus, are inserted with it into the ulna. In most of the Carni- 
vora the clavicle is represented simply by a tendinous intersection on the deeper surface 
of the cephalo-humeral muscle. In this family the most striking development of the 
cleido-occipital is found in the peculiar arrangement, before alluded to, in the striped 
Hyaena, Polecat, and Genette, and to a less marked degree in the Coati, as figured in 
Cuvier and Laurillard’s 4 Becueil.’ A second clavicular head of the cleido-occipital 
crosses superficially over the cleido-mastoid to j oin the sternal origin of the sterno-mastoid, 
with the hinder border of which at the sterno-clavicular joint it is united, and not at all 
with the cleido-mastoid. Thus is produced an apparently double or second sterno-cleido- 
mastoid muscle, imbricated upon the true one, and strikingly resembling the human variety 
I have described in an earlier part of this paper. The Marmot shows a similar arrangement. 
