102 
PROFESSOR WOOD OX THE NECK- AND SIIOULDER-MUSCLES. 
In the Hyrax capensis, which presents many points of connexion in its muscular system 
with the Rodents on the one hand, and the Pachyderms on the other, the arrangement 
of these muscles admits of the best reading, I believe, by the homologies herein indicated. 
As described by Mueie and Mivaet, the sterno-cleido-mastoid apparatus is represented 
by three muscles - One, attached to the occipital bone, and inserted with the biceps 
into the ulna, is the cleido-occipital, joining in the formation of a compound cephalo- 
Jiumeral with some of the segregated fibres of the pectoralis and of the brachialis anticus. 
Another portion, the true sterno-mastoul , is connected above with the angle of the jaw 
and masseter ( sterno-maxillary v. mandibular of the Ruminants and Pachyderms, see 
also Meckel, Anat. Comp. t. vi. p. 163) ; below, it joins its fellow of the opposite side 
at and above the sternum. A third portion, a very slender muscle, somewhat resembling 
the omo-hyoicl , is attached in front to the paramastoid process, and joins behind with 
the first on its deep surface : this third part, according to the homologies herein sus- 
tained, would be the true cleido-mastoid muscle, the name which is bestowed by Mueie 
and Mivaet upon the first described portion (Proc. Zool. Soc. April 11, 1865, pp. 331, 
332). 
The limits of this paper will hardly permit me to follow further the various develop- 
ments of the foregoing group of muscles in the Pachyderms, Ruminants, and the rest 
of the Mammalia. It will be enough for my purpose if I have succeeded in showing the 
more important forms which, when occurring as varieties in the human subject, tend to 
exhibit in a sufficiently marked manner what may be considered as proofs and examples 
of the Darwinian principle of reversion , or law of inheritance , in this department of 
anatomical science. 
I will now proceed to consider another group of occasional varieties in the human 
shoulder, which I believe I was the first to connect with their homologies in the animal 
kingdom, and one of which, the scapulo-clavicular , I was the first to discover and name 
in the human subject. 
Sterno-cliondro-scapular and Scapulo-clavicular Muscles . — In my paper read before the 
Royal Society in 1864, I figured and described examples of an apparently double deve- 
lopment of the subclavius muscle. The upper portion had the normal attachments of 
the subclavius muscle ; the lower part, separated from it by a distinct areolar interval, 
somewhat wide externally, arose, in one case, by a distinct tendon from the sternum and 
first rib-cartilage, but, in another, in common with the subclavius. Passing’outwards as a 
somewhat fusiform muscle over the axillary vessels and nerves, it was inserted fleshy 
into the tubercle of the coracoid process and conoid ligament. In my paper published 
in the ‘Proceedings of the Royal Society’ in 1865, I figured and described a similar 
muscle, found on the left side of a thin female subject (Plate IX. fig. 10, i). It was a 
roundish fusiform muscle, arising tendinous from the first rib-cartilage close to the ster- 
num, and inserted into the suprascapular ligament and base of the coracoid process, 
where it was connected with the origin of the omo-hyoid muscle (o). 
In the same shoulder a distinct band of muscular fibres, about an inch wide and an 
