220 NATURAL HISTORY SOCIELY OF DUBLIN. 
normal and unalterable position of the lower or pelvic limb, we can 
easily understand why this muscle is not developed as a pronator. 
Not being a pronator in function, we need not expect to find its typical 
insertion preserved ; for, whenever a muscle loses its usual action, and 
assumes another function, its insertion must be the part to become 
varied, as that is one of the two essential conditions determining 
action (the other being direction). In the prone position, likewise, for 
an obvious reason, a pronator runs more longitudinally and less ob- 
liquely than in the supine state; hence, on @ priore grounds, we may 
expect to find the homotype of the pronator teres as a longitudinally 
directed muscle, not necessarily preserving its typical insertion, but 
probably arising superficially from the flexor side of the inner condyle, 
over the other flexor muscles, over the great fiexor nerve, over the 
artery whose branch perforates the interosseous membrane (ulnar or 
popliteal, giving off posterior interosseous or anterior tibial), and forming 
probably an inner boundary to the space in which the limb artery lies 
(anticubital or popliteal). Now, all these conditions are fulfilled by 
the inner head of the gastrocnemius muscle, a part perfectly separate 
in its nature from the outer head, as they are quite distinct in the 
early embryo, but which, by coalescing with other muscles, can utilize 
its power, which is perfectly useless for its own special purposes. 
This muscle is liable to very little variation, and is constantly present 
in the animal series. 
Of the short or quadrate pronator, the traces in the pelvic limb are 
scant. I have, on a former occasion, given some reasons for believing 
that the inner head of soleus represents the upper part of this muscle 
(see vol. 11. of the ‘‘Journal of Anatomy,’ p. 8), and also that the peroneus 
sextus (quartus, Otto), or peroneo-calcanian muscle might represent the 
pronator quadratus proper. Certainly this muscle is the close parallel 
of the anomaly of pronator quadratus quoted above, and is very similar 
to the arrangement of this muscle in the pig (called by Gurlt abductor 
pollicis longus), or to the lower attachment of it in the tiger quoted 
above. The only instance in which a true pronator quadratus has 
been found in the hinder limb, as far as I am aware, was in a fine 
alligator which died in the Dublin Zoological Gardens, February, 1869, 
in whose hind limb a distinct transverse fasciculus of fibres crossed from 
‘tibia to fibula perfectly differentiated from all the other muscles in this 
locality. 
WEDNESDAY, MARCH 4, 1869. 
Davip Moors, Ph. D., M. R. I. A., in the Chair. 
Tue Minutes of the last Meeting were read and approved of. 
Dr. J. Barxer, V. P., read Notes on tue Dissection or Lemur 
NiIeRIFRONS. 
