186 The Phylogeny of the Forearm Flexors 
‘is unrepresented in the reptilia, the weight of evidence seems to me to 
point that way. 
The flexor carpi radialis seems to be equivalent in the two groups, 
while the pronator radii teres seems to correspond to the radial portion 
of the amphibian palmaris superficialis. In Liolepisma the nerve 
which passes to the flexor carpi radialis arises from the N. brachialis 
inferior longus before its division into the deep and superficial rami, 
but it is more nearly associated with that portion of the nerve which 
becomes the R. profundus and I have therefore associated it with that 
ramus. The branch to the pronator teres, on the other hand, was the 
first branch from the R. superficialis medialis and there is, accordingly, 
good reason for beleving that the pronator teres and the flexor carpi 
ulnaris are quite distinct structures. 
The reptilian pronator accessorius is supplied, like the pronator 
quadratus, from the R. profundus and I see no reason for doubting 
the conclusion of Fiirbringer (1870), that it represents the upper por- 
tion of the amphibian quadratus. 
The homologies of the amphibian and reptilian muscles as described 
above may be tabulated thus: 
Amphibia. Reptilia. 
Ulno-carpalis Xe 
Epitrochleo-anconeus Epitrochleo-anconeus 
Flexor carpi ulnaris Flexor carpi ulnaris (lateral head) 
( Flexor carpi ulnaris (medial head) 
Palmaris superficialis ~ Palmaris communis (superficial portions) 
Pronator radii teres 
Palmaris profundus III ) Palmaris communis 
Palmaris profundus II f (longitudinal deep portions) 
3 Palmaris communis 
Palmaris profundus I | 
(oblique deep portions) 
{ Pronator quadratus 
| Pronator accessorius 
Flexor carpi radialis Flexor carpi radialis 
Pronator quadratus 
II. THe Forearm FLExors oF THE MAMMALIA. 
In the amphibia and reptilia it is evident that the forearm muscles 
proper end at the wrist joint, their action upon the digits being through 
their insertion into the palmar aponeurosis, from which the palmar 
muscles arise. In the mammalia it is customary to regard the long 
digital flexors as extending from their antibrachial origins to the pha- 
langes, and in comparing them on this basis with the corresponding 
muscles of the lower groups, it is necessary to assume that there has 
been either an extension of the origin of certain palmar muscles proxi- 
