ON THE DEEP PLANTAR TENDONS IN BIRDS. 293 
Pheenicophaés, sp. ? Leptoptilus argala. 
Eudynamis orientalis. Ardea sumatrana — very 
~ Cuculus canorus. slender). 
Nestor notabilis. "cinerea (vinculum scarcely 
Chrysotis festiva. exists). , 
ochrocephala. Cancroma cochlearia. 
Ara chloroptera. Geopelia cuneata. 
Baza lophotes. Ibis rubra. 
Syrnium aluco (vinculum ‘very Platalea ajaja. 
broad). Eurypyge helias. 
- In Ardea cinerea and in A. sumatrana, here mentioned, the vinculum 
is stated to be extremely feeble. In Botawrus stellaris this condition is 
carried a step further, the vinculum being quite wanting. Prof. 
Sundevall states that such is the case only in the Passeres and in 
Upupa ; here, however, is a slight exception to that generalization. 
Frequently the vinculum above referred to is so considerable in 
strength that it makes the flezor longus hallucis appear to fuse with 
the flexor perforans digitorum, and only to send a slip before doing so 
to the hallux. This condition is evidently but an inconsiderable modi- 
fication upon the previously described typical arrangement (fig. 2, 
p- 291). It is, however, a stepping-stone to others, which it assists in 
explaining. It is found in the following birds, which I have dissected 
(it will be noticed that they have the hallux comparatively a a 
cant) :— 
Palani mantelli. Cygnus nigricollis. 
& Nothura maculosa. fF odiceps minor. 
= Chenalopez egyptiacus. Phalacrocoraz carbo. 
In many of the Accipitres Diurne a slight modification of this 
arrangement is observed. The flezor longus hallucis divides into two 
moieties opposite the lower end of the tarso-metatarse, one of which 
runs to the hallux. The other partis the representative of the vinculum 
of the above-mentioned birds; it is peculiar, however, in that, instead of 
joining the tendon of the flexor perforans digitorum before it is dis- 
tributed to the anterior toes, it mostly runs down to blend with the 
slip which is associated with the inner of these (digit 2) only (fig. 3). 
This condition I have observed in 
Haliaétus albicilla, Tinnunculus alaudarius. 
In Geranoaétus aguia and in Polyborus brasiliensis, besides the 
special tendon from the hallux-muscle to the second digit, there is a Page 344. 
broad thin vinculum present, as in Gallus. In the Accipitres Diurne 
the arrangement of the tendons therefore differs in different groups— 
