Cu. I.] OF THE DODO. 103 
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The shaft of the metatarsus has nearly the same width (seven lines) in its middle third, but expands 
greatly towards each extremity and chiefly inwards, so that the inner margin is more concave than the 
external. The shaft is triangularly pyramidal in its two upper thirds, but compressed in the antero-posterior 
diameter below; the mesial ridge (calcaneal buttress), to which the lateral surfaces incline posteriorly, sub- 
siding inferiorly towards the articular facet for the posterior metatarsus. The great development of the calcaneal 
buttress, which is based on the stem of the metatarsus, is one of the characteristics of that bone in Pigeons. 
The section of the shaft is hence triangular above, with the base in front, and the apex corresponding to 
the calcaneal ridge ; below, the section is transversely oblong or suboval. 2 
The anterior surface of the shaft is concave vertically in its upper and inner portion; in the rest of its 
extent it is straight longitudinally, and convex transversely. In its upper third, it presents a mesial 
elongated obovate concavity, between the prominent lateral metatarsal elements ; the outer of which is most 
convex, and placed on a plane anterior to the mner, which is more expanded transversely, but less tumid. 
The median element forms the floor of the concavity, which is deepest beneath the overhanging edge of the 
proximal extremity; into it open the anterior orifices of the short canals, which perforate the bone in the 
antero-posterior diameter, and indicate, as in all other birds, its compound origin; both have a longitu- 
dinally oval form, but the internal is double the size of the external, the upper angle of which is partially 
concealed. The rough elongated and prominent oval tubercle which gives insertion to the tendon of the WZ. 
tibialis anticus, commences one line beneath the lower border of the inner foramen, and extends along the 
internal margin of the concavity, presenting a deep groove on its upper angle. Below, the anterior surface of 
the external metatarsal element slopes slightly backwards towards the broad outer border; while that of the 
inner elements is more rapidly rounded off centrally towards the inner edge. 
The external third of the anterior surface, which twists on itself above, where it forms the outer wall of 
the concavity, is thus separated from the inner two-thirds, by a raised imter-muscular line, which descends 
from the inner margin of the external inter-osseous foramen to that of a well marked groove, commencing 
about half an inch above the oval aperture, or short oblique canal, that transmits, as usual, the tendon of 
the IZ. adductor annularis ;: this muscle arises from the surface indicated. One line external to the imter- 
muscular ridge, a medullary foramen, directed downwards, perforates the shaft below its centre. Three 
distinct muscular impressions are met with internally ; the outer descends from between the lower angles of 
the inter-osseous foramina, gradually increasing in breadth beneath the centre of the shaft, towards the middle 
trochlea, half an inch above which it terminates, and gives origin to the Hvtensor medii. The internal and 
inferior impression, from which the MW. adductor indicis arises, extends from the tadialis tubercle as low as the 
external area, separated from it by an oblique sinuous line, which becomes fainter as it ascends, and dis- 
appears beyond the centre, being replaced by a slight groove; its upper and inner boundary descends 
obliquely inwards from the same tubercle, and reaches the immer margin towards its centre. The anterior 
surface of the inner metatarsal element, above this oblique line, gives attachment to the M/.extensor pollicis ; 
it is deeply pitted above on each side of a raised subcentral line, and below exhibits two or three faint 
grooves parallel to its lower boundary. 
A small medullary foramen occurs nearly on a level with the lower angle of the posterior metatarsal 
facet, and one line external to the boundary between the surfaces for the I. M. eatensor medi and adductor 
indicis, which are deeply pitted, especially below. 
The external border, which is uncovered by muscle, is narrow below, but increases in breadth as it 
ascends, and turns round the convex outer metatarsal element so as to appear anteriorly; its anterior 
1 The inter-osseous muscles are named in relation to the median line of the body, not to the axis df the foot, 
as in English works on anatomy. 
25 
