J. Playfair McMurrich 201 
original flexor communis separated to join the sublimis tendons, leaving 
only the ulnaris and radialis attached to the profundus tendon. In 
brief, starting with a condition in which there is no definite distinction 
between a superficial and a deep layer of antibrachial flexors, there has 
been a gradually increasing separation of the superficial layer, until, 
finally, we have in the flexor sublimis plus the palmaris longus the exact 
homologue of the palmaris superficialis of the reptilia. 
After what has been already said it is perhaps hardly necessary to 
point out that my views as to the significance of such anomalies as the- 
occurrence of a distinct centralis in man are quite different from those 
expressed by Windle. For I do not believe its occurrence is the appear- 
ance of a muscle usually absent, but, on the contrary, the muscle is 
always present as a constituent of the sublimis and its recognition as a 
distinct structure is due to its failure to unite with the other components 
of that muscle. Indeed, it seems highly probable, that we are in error 
in stating. as is usually done, that the palmaris longus is not infrequently 
absent in man; we should rather say that in many cases it becomes 
completely incorporated with the sublimis, just as a portion of it, as 
represented in the lower forms, does normally. 
The progressive development of the sublimis in the mammalia, to- 
gether with the homologies of the flexor muscles in various forms, may 
be shown as follows: 
OPOSSUM AND CAT. 
Palmaris ————— Palmaris 
Condylo-ulnaris ____>—. Sublimis 
Condylo-radtais 
Centralis res ss _ Profundus 
Radialis ——___——_ 
Ulnaris— 
CEBUS CAPUCINUS. 
Palmaris Palmaris 
a Sublimis 
Condylo-radialis 
Centralis — —— - Profundus 
Radialis Se 
ae 
Ulnaris — 
ORANG-OUTANG. 
Palmaris ——_ - 
Condylo-ulnaris —__~— 
— Sublimis 
Centralis = 
Condylo-radialis 
Radialis 
Ulnaris 
Palmaris 
— Profundus 
MOUSE. 
Palmaris Palmaris 
Condylo-ulnaris Sublimis 
Condylo-radialis —__ 
Centralis - —— Profundus 
Radialis ee 
Ulnaris 
CYNOCEPHALUS MAIMON. 
Palmaris — 
— 
Condylo-ulnaris ———__ 
Centralis 
Sublimis 
Condylo-radialis aia 
Radialis — ia Profundus 
Palmaris 
Wlnaris= =< Se 
MAN. 
Palmaris ——__ Palmaris 
Condylo-ulnaris —— 
Centralis__-_——— — >} Sublimis 
Condylo-radialis sae 
R208] —————_—_—— Longus pollicis 
Ulnaris —— —— Profundus 
