Cu. I.] OF THE DODO. 109 
The posterior metatarsus in the Dodo (Plate XI. Fig. 7—10), is formed by a thick oblong plate, 
twisted on itself from behind forwards, and from within outwards ; the line of flexure corresponding to its 
diagonal. The channel thus formed (4. Fig. 9) lodges the flezor tendons of the hind toe. The lower 
extremity supports the transversely elongated trochlea, which is very slightly concave in front, but behind, 
it is grooved for the deep flewor tendon; it is broader internally than externally, and also projects back- 
wards beyond the plane of the stem toa greater extent internally. 
The thin outer margin of the triangular posterior portion of the stem is concave : its lower angle forms 
a subquadrate process projecting outwards beyond the trochlea (styloid process), which gives attachment to 
the annular ligament ; its anterior surface is covered by a thin layer of synovial cartilage, the superficial 
flexor tendon of the inner toe gliding on it. The upper extremity, which articulates with the metatarsus, 
viewed from before, consists of a semicircular plate, forming the anterior wall of the channel ; its thick 
convex, external border is roughened in front for the attachment of the strong inter-osseous ligament ; the 
upper part of its subconcave anterior aspect is covered by articular cartilage, and the concavity probably 
gave origin to some fibres of the MZ. adductor indicis. The floor of the channel is wider below than above ; and 
the lower untwisted portion of the stem projects obliquely backwards from the articular plate, which is per- 
pendicular when in apposition with the metatarsus ; the rounded inner margin of the former expands above 
into the triangular surface of the floor of the channel. The tendon of the JZ. extensor pollicis passes along 
the posterior surface, and is bound down immediately above the trochlea by an annular ligament, attached 
externally to a roughened portion of the outer edge, and internally to a narrow pit close to the inner 
border. 
In all Pigeons, the shape of the posterior metatarsus is precisely the same as in the Dodo ;—the styloid 
process exists in all (Plate XT. Fig. 16, 18, 25, 31, 37, 43). After observing that peculiar character, I 
was kindly allowed to test the Columbine atlimty of the Didunculus, by removing its accessory metatarsal 
(Plate X. Fig. 10, 10 a), which proved to be a miniature of that in the Dodo. In the arboreal Pigeons, it 
is relatively larger than in the Gowrine, and attains its maximum in Lopholemus. 
In the Gatline, the posterior metatarsus is relatively shorter, and the twist less distinctly marked than in, 
the Dodo and Pigeons. In the common Cock, the curved plate is much thicker, and hence the channel 
more open, but the under or trochlear portion projects relatively farther back. In the Cracide, it is 
thinner, and more distinctly twisted ; and from its greater elongation, its articular surface is placed lower 
down. In Megapodius, the outer margin of the curved plate is less concave, concealing from behind the 
expanded articular surface ; but the essential distinction in all, lies in the absence of the styloid process. 
In Cathartes, it is very small, subpyramidal, and not bent on itself; the anterior surface is nearly flat ; 
its lower extremity is elevated considerably above the internal trochlea, so that the hind toe is, as in the 
typical Gadling, &c., above the plane of the heel. 
Inthe Vulture, it is narrow transversely, and shghtly twisted, the anterior surface being broadly con- 
cave, and the lower extremity placed nearly in contact with the immer margin of the metatarsus. In the 
Eagle,! also, the peculiar flexure of the posterior metatarsus almost disappears, the bone being nearly flat, and 
consequently it is readily distinguished from the corresponding bone in the Dodo; it is also destitute of 
the styloid process ; and, as in Cathartes and the Vulture, the lower portion is shortened, and projects 
backwards only to a very slight extent. We therefore find, that as in the metatarsus, so also in the accessory 
metatarsal, the Dodo deviates more from the Raptores than from the Gallina, butis really distinct from both. 
1 The figure furnished by Mr. Owen, of this bone, in situ, is evidently taken from a badly mounted skeleton, in 
which it is placed in an unnatural position, as theligaments would retain the accessory metatarsus close to the main one. 
