22 A Review of the Muscles used 
tendon of the flevor longus hallucis is either superficial or 
external to the tendon of the other flexor mentioned. 
This fact is useful to be borne in mind in identifying 
these tendons in our dissections. Now after they pass a 
short distance down the back of the tarso-metatarsal bone 
their behavior in different birds is quite diverse, and a few 
examples of it will be here presented in order to show that 
when our knowledge becomes more full in the premises, 
the character will prove a useful one in classification of birds; 
and also it is hoped to induce those interested in the science 
of anatomy to undertake and carefully record researches 
upon this subject. Before arriving at the podal phalanges, 
and in the sole of the foot of any bird, these tendons divide 
into a sufficient number of slips to be distributed to the for- 
mer, one slip going to each toe. The method of division 
is the same for the bulk of avian families, and the more 
universal type is well exemplified in the Common Chicken 
(Gallus). 
Figure 12 of this paper shows this arrangement in the 
Fowl, and there we observe that the tendon of the flexor to 
the first toe is external to the tendon of the flexor perfo- 
rans digitorum as it passes the ankle-joint. 
At the back of the tarsus it crosses the latter superficially, 
and then passing directly to the under side of the hind-toe 
it becomes inserted into the base of its ungual phalanx. 
Now the larger tendon of the f. p. digitorum, after arriv- 
ing at the sole of the foot, trifurcates, and a slip is sent to 
the under side of each anterior toe, where passing forwards 
they too become inserted at the bases of the ungual digits 
of the respective phalanges. Just above this trifurcation 
the tendons of these two muscles, however, are connected, 
and that by a fibrous vinculum (Fig. 12, V) which passes 
between them. 
The fibres of this vinculum come off from the tendon of 
the flexor longus hallucis, and pass downwards to soon 
merge with the fibres of the tendon of the flexor perfor- 
ans digitorum at the crossing. This arrangement, of course, 
influences the action of flexion in the foot of the passerine 
bird, but this question does not especially concern us here. 
