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Show 1875.] PLANTAR TENDONS IN BIRDS. 343 tarso-phalangeal joint into three tendons, one running to the ungual phalanx of each of the three anteriorly directed toes. The flexor longus hallucis'is inserted into the ungual phalanx of the hallux, but it sends downwards near the middle of the tarso-metatarsus a vinculum to join the tendon of the flexor perforans digitorum just before the trifurcation of that muscle (figs. 1 and 7). This condition is found in the following birds which I have examined :- Gallus bankiva. Baza lophotes. Megacephalon maleo. Syrnium aluco (vinculum very Fulica atra. broad). Musophaga violacea. Leptoptilus argala. Schizorhis africana. Ardea sumatrana (vinculum very Crotojjhaga sulcirostris. slender). Phcenicophccus, sp.? cinerea (vinculum scarcely Eudgnamis orientalis. exists). Cuculus canorus. Cancroma cochlearia. Nestor notabilis. Geopelia cuneata. Chrysotis festiva. Ibis rubra. ochrocephala. Platalea ajaja. Ara chloroptera. Eurypyga helias. In Ardea cinerea and in A. sumatrana, here mentioned, the vinculum is stated to be extremely feeble. In Botaurus 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 flexor 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 modification upon the previously described typical arrangement (fig. 2, p. 341). 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 insignificant) : - Apteryx mantelli. Cyynus nigricollis. Nothura maculosa. Podiceps minor. Chenalopex agyptiacus. Phalacrocorax carbo. In many of the Accipitres diurnse a slight modification of this arrangement is observed. The flexor longus hallucis divides into two moieties opposite the lower end of the tarso-metatarse, one of which runs to the hallux. The other part is 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 distributed 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 Haliaetus albicilla, Tinnunculus alaudarius. In Geranoaelus aguia and in Polyborus brasiliensis, besides the |