9S 
PEOFESSOE WOOD ON THE NECK- AND SHOULDEE-MTTSCLES. 
A further light is thrown upon this arrangement by that found in the Donkey, of 
which the succeeding figure (Plate XI. fig. 21) was drawn from a sketch made also from 
nature by Mr. Nettleship. In this animal the acromio-trachelien ( levator claviculce) 
[e e) arises by four digitations from the four upper cervical transverse processes, and is 
a far larger muscle than the cleido-mastoid, much resembling in appearance the origin 
of the human levator anguli scapula?,. The cleido-mastoid portion (b), however, arises, 
not in common with the rectus capitis anticus (u) from the basilar process, but with the 
rectus lateralis (w) from the paramastoid process just behind the ear, as in most of the 
Mammalia, and clearly asserting its homology with the human cleido-mastoid. The 
two muscles have exactly the same relation to each other as those of the Fallow Deer, 
and form, in the same manner, the compound levator humeri muscle (b c). As an evi- 
dence of the like tendency to transposition evinced by this group of muscles in the large 
heavy animals, both long- and short-necked, I may allude to the fact that in the Ass and 
Horse, as well as in the Camel, Elephant, Hyrax, and most of the Ruminants, the sterno- 
mastoid is inserted into the angle of the mandible (hence called sterno-maxillaris 
vel mandibularis by veterinary anatomists). In the Peccary, Hippopotamus, Pig, and 
Tapir it is, however, inserted into the mastoid process, with a slip to the transverse 
process of the atlas in the Hippopotamus. 
The question now arises, — What, then, is the homologue of the muscle which has been 
usually considered by writers on the subject as the cleido-mastoid , viz. that marked c in 
the figure of the Rabbit (Plate X. fig. 16) 1 Its superficial position in relation to, and 
parallelism with the fibres of, the sterno-mastoid (a), its attachment to the ridge of the 
occipital bone as far as that of the trapezius , its intermediate position here between 
these two muscles, together with its superficial position at its attachment to the clavicle 
(#) in relation to the other muscle which I have affiliated to the cleido-mastoid ( b ), which 
it assists in forming the compound levator humeri muscle ( b c), all lead me to consider 
it as the representative of the cleido-occipital muscle which I have described as a human 
variety. A comparison with the same muscle in the Guinea-pig (Plate X. fig. 17, c), 
and still more in the Squirrel (fig. 18, c) and Norway Rat (Plate XI. fig. 26, c), will 
render this more clear. In the Guinea-pig the muscle (c) has its cranial attachment to 
the ridge of the occipital bone, and not to the mastoid, reaching from the insertion of 
the sterno-mastoid to that of the trapezius. No other muscular fibres, except a few 
which join it high up from the last-named muscle, and which may represent the true 
cleido-mastoid , assist it to form the levator humeri (d) in the arm. It is apparently the 
only muscle from the upper part of the neck or head which is connected with the 
clavicle (x). 
In the crested Agouti (. Dasyproctci cristata ), Mivakt and Mukie found a very similar 
blending of the two corresponding muscles on the right side [op. cit. p. 391). These 
authors recognized in this animal the homology of the levator claviculce muscle, which 
they describe as arising by a tendon from the basis crani , — one part (the inner) being 
inserted into the outer end of the clavicle (the cleido-mastoid of this paper), and the 
