J. Playfair MeMurrich 193 
able modification in the topographic relationship of the muscles. A 
muscle, the profundus III for example, which is clearly a portion of the 
deep layer in the amphibia, becomes, in the mammalia, the superficial 
flexor sublimis, altering its topographic relations to the principal nerves 
of the arm. Such an alteration is of course possible, but its probability 
is greatly diminished if an homology can be found which does not de- 
mand it, and I have shown that there is such an homology. Indeed, 
the superficial and deep layers of the amphibian forearm musculature 
are clearly recognizable in both the reptilia and the mammalia, and 
there seems no reason for manufacturing homologies which require 
their confusion. Furthermore, it seems to me that an homology which 
demands an extensive migration of muscle masses across joints should 
be viewed with suspicion, and such a migration is demanded by Hisler’s 
identification of the palmaris profundus III with the flexor sublimis. 
With the enormous reduction which he supposes to have occurred in the 
palmaris superficialis, room is afforded upon the internal condyle for 
such a migration, but as has just been indicated and as will be shown 
later there is evidence to show that this reduction has not occurred. 
Hence, independently of the a nriort objections to a migration of a pro- 
fundus muscle across a joint, there is, in the present case, an additional 
objection on the ground that the muscle would have found the territory 
for which it was striving already preémpted. 
Finally, a word concerning the identification of the palmaris pro- 
fundus I with the anomalous flexor radialis brevis. I have had an oppor- 
tunity for studying this muscle in a subject dissected last winter in the 
Anatomical Laboratory of this University, and from its general relations 
I should be strongly inchned to regard it as a portion of the flexor carpi 
radialis, though I cannot exclude the possibility of its+derivation from 
the pronator quadratus. In either event, however, I agree fully with 
Le Double (1897) in assigning it to the group of progressive anomalies: 
“Tl est la conséquence du morcellement plus complet de la masse flexo- 
pronatrice, et non un ‘remnant’ de cette masse, pour me servir d’une 
expression du professeur Humphry.” 
Ill. THe ANTIBRACHIAL FLEXoRS IN MAN AND THE EVOLUTION OF 
THE FLEXOR SUBLIMIS. 
The flexor muscles of the forearm in man present certain departures 
from the condition which has been considered fundamental for the mam- 
malia, the more important of these departures concerning the pronator 
radii teres and the flexor communis digitorum. The peculiarity in the pro- 
