33 
broader triangular layer of carneous fibres ; which arise anterior to 
the preceding, just below the coracoid socket of the sternum, and 
converge as they wind over the shoulder-joint to be inserted into 
the upper surface of the proximal extremity of the humerus, of which 
they thus become an elevator. 
The pectoralis minor seu tertius arises above and between the ori- 
gins of the pectoralis secundus and the anterior strip of the pectoralis 
major, also partly from coracoid process ; its fibres converge to be in- 
serted into the proximal end of the humerus, above and behind the 
pectoralis major. 
Coraco-brachialis.—This is represented by two small strips of mus- 
cular fibres which rise from the posterior part of the coracoideum, 
and are inserted, one directly below the other, into the proximal 
third of the humerus. 
Obs.—The close adherence to the ornithic type of the muscular 
system of the anterior extremity in the Apteryxr is very remarkable, 
especially as regards the position and course of the pectoralis medius, 
since the physiological conditions of the circumstances attending that 
muscle are wanting in the Apferyz. 
Here we have a true bird, exhibiting a remarkable modification of 
the whole ornithic structure, in reference to exclusively terrestrial 
life and nocturnal habits ; and we learn, I think, from this adherence 
to a typical organization, in a very rare exception, that the teleolo- 
gical conclusions respecting that typical construction, as it is mani- 
fested in the general rule, are in no ways affected by such an excep- 
tion; because the modification of one part necessarily affects that of 
many others, perhaps of the whole body. If, for example, the fixa- 
tion and structure of the lungs require a broad sternum and con- 
comitant modifications of the coracoid and scapula for the mecha- 
nical part of the respiratory process, then it may be more convenient 
for the levator of the humerus to rise below that bone from the 
sternum, and actin the due direction by a modification of its course ; 
although the locomution of the bird may in no way be facilitated by 
the aggregation of muscle beneath the centre of gravity, nor the size 
of the levator be such as to render its particular position a matter of 
any consequence in regard to that centre. 
The motions of the rudimental wing and its terminal hook would 
seem to be produced as much by the cutaneous muscles which con- 
verge to be inserted into the integument connected with it, as by 
the feeble representatives of the true wing-muscles above described. 
Muscuzs or THE PostER10R ExTREMITY. 
The most superficial of the muscles on the outer side of the leg is 
that broad thin expanded one which combines the functions of the 
tensor vagine and rectus femoris, and also, according to some anato- 
mists, as Cuvier and Meckel, those of the gluteus maximus ; since 
however it is exclusively inserted into the leg, I shall describe it with 
the other muscles moving that segment of the posterior extremity. 
The removal of this muscle, of the sartorius, and the biceps cruris, 
is requisite to bring into view the glutai. 
B2 
