J. Playfair McMurrich 419 
slips are the urodele equivalents of the lacertilian stratum superficiale. 
If this view be adopted the homologies of the muscles in the two groups 
may be tabulated as follows: 
Urodeles. Lacertilia. 
Flexor brevis superficialis stratum 
: Soper superficiale. 
eee Cray Supericialis Flexor brevis superficialis stratum 
profundum. 
Flexor brevis  medius fasciculus Flexor brevis medius stratum super- 
tibialis. ficiale. ‘ 
Flexor brevis medius fasciculus Flexor brevis medius stratum pro- 
fibularis. fundum. 
Flexores breves profundi. Flexores breves profundi. 
Intermetatarsales, Ligg. intermetatarsalia. 
III. THe PLantar MUSCLES oF THE MAMMALIA. 
In 1878 Ruge published two important papers dealing with the plantar 
muscles of the mammalia, one, 78, being a consideration of the 
muscies of the human foot from the embryological standpoint, and the 
second, 78a, a comparative study of the deeper plantar muscles. In 
the first paper two important results were recorded, namely, (1) the 
plantar nature of both the dorsal and plantar interossei, and (2) the 
primary unity of the adductor hallucis and the transversus pedis. In the 
second paper, disregarding the superficial muscles and relying upon the 
doctrine of the immutability of the nerve supply of muscles, the author 
separates these muscles which are supplied by the medial plantar nerve 
from those innervated by the lateral plantar, and divides the latter into 
two groups, one of which the contrahentes, hes to the plantar side of 
the deep branch of the lateral plantar nerve, while the other, formed by 
the interossei, lies dorsal to the nerve. 
In the same year that Ruge’s papers appeared Cunningham, 78a, pub- 
lished the results of his extensive comparative studies of the plantar 
muscles, furnishing later, 82, a more detailed account of his observa- 
tions. Like Ruge, he disregarded the superficial muscles, but, on the 
other hand, he declined to accept nerve supply as an absolute criterion 
for muscle homology, and found in what he termed the “ intrinsic” 
muscles, representatives of the same three layers he had already demon- 
strated, 78, in the hand. ‘The most superficial to these layers lies dor- 
sal to the tendons of the long flexor and plantar to the deep branch 
of the lateral plantar nerve; it is termed the plantar layer of adductors 
