g^g PEOFESSOE OWEN ON THE ]MEGATHEEniM. 
surface externally. The lower part of the vertical prominence is most produced {il. 
2 
The fourth metatarsal (Plate XLI. fig. 1, m.) has its base compressed lateinlly, and 
expanded vertically ; hut the distal end is stiU more produced in that direction, so as 
to be almost hammer-shaped. The verticaUy extended articular surface at the base of 
this metatarsal is narrow, convex transversely, and adapted to the channel m the 
cuboides (Plate XL. fig. 2, p iv). On the inner or tibial side^ of the base is the articular 
surface, concave posteriorly, less convex anteriorly, for the mterlockmg jomt with the 
‘ third ’ metatarsal. In front and below this articular surface is^ a very rough honey- 
combed tract of bone for firm syndesmotic junction with the similarly modified surface 
of the third metatarsal. 
On the outer or fibular side of the base are two articular surfaces for the fifth meta- 
tarsal : the hinder and smaller one is flat, and is continued, at nght angks, ivith the 
basal surface ; the larger surface is subcircular and rather undulatmg ; m front and 
below these surfaces is a narrow rugged tract for ligamentous junction with the fifth 
metatarsal. The part of the shaft of the fourth metatarsal which stands out fiee is 
smooth upon its inner and upper sides, is traversed by a wide oblique tendinal groove 
below, and is rather rough and irregular externally. 
The vertically produced distal surface presents a large rough protuberance at its upper 
part (Plate XL. fig. 1, iv), and three protuberances at its under part, of which the 
innermost is the most produced, the outermost the least. The articular surface resem- 
bles in character that on the end of the third metatarsal, but is relatively smaller ; it 
consists of a longitudinal median prominence, continuous with a smooth naiTow tract on 
the inner side, on which surface articular cartilage and synovial membrane seem to have 
existed at only a small part at its lower end. On the outer side, the smooth tract is 
limited to the upper half of the prominence ; this is slightly concave vertical!} or length- 
wise. It is a form of articulation calculated rather for firm and unyielding junction 
than for flexibility. 
The outermost metatarsal (Plate XLI. fig. 1, m .). answering to the fifth of the penta- 
dactyle foot, is the longest, but from its more backward articulation with the tarsus it 
does not reach so far forward as the fourth. 
The proximal end is a free rough tuberosity, somewhat more than an mch antenor 
to which, on the tibial side, is the oval slightly concave articular surface adapted to the 
cuboides (Plate XL. fig. 2, v), which surface is continuous with the short transverse 
flattened surface for the fourth metatarsal; and, in advance of this, is the laigei, sub- 
circular, slightly undulated surface for the corresponding suiTace on the fourth meta- 
tarsal. The second surface is on the middle of the inner siuface of the fifth metatarsal, 
and is bordered in front and beneath by the very rough honeycombed surface for 
ligamentous junction with the adjoining metatarsal. This combination of s^movral nnth 
syndesmotic joints admits of that degree of slight elastic movement of the very fii'nily 
attached fourth and fifth metatarsals, which must have facilitated the heaiy tread ot the 
