ON FOSSILS FROM NEW ZEALAND 159 
below this for about 4th of an inch, is a deep narrow pit, which, how- 
ever, penetrates but a very little way into the substance of the bone. 
From the inner margins of this pit, three or four thin sharp ridges arise 
and pass spirally downwards and inwards, the lower ones being much 
more inclined than the upper; the uppermost ones extend on to the 
inner surface of the bone, the lower stops short on its front face, 
Immediately below the interarticular tuberosity the face of the bone 
is greatly excavated ; and this excavation ends below in a very deep 
groove, which extends through the whole length of the bone, to the 
fissure which separates the outer and middle condyles. At the 
superior end of the groove, an oval aperture leads into the canal 
which terminates in the foramen seen on the posterior face of the 
bone. The middle part of the groove is deep, but not perforated, 
while its distal end is shallower. The upper end of the groove is on 
the same level as the deep pit to which I have previously referred; a 
somewhat narrow, but strong, bony partition separates the two, and 
is continued down into the substance of the middle metatarsal bone, 
which constitutes the inner wall of the groove. Just below the pit 
and foramen this wall presents an oval roughened space 4th of an 
inch long, for the’ insertion of the tendon of the ¢zbzal7s anticus. The 
outer wall of the groove is more prominent than the inner, and has 
the form of a strong bony column, which ends above in the outer 
articular facet; below this, however, it presents a rough transverse 
ridge, descending lower on the outer than on the inner side, while 
superiorly and internally it arches over the summit of the groove 
towards the two inner vertical ridges which have been described. 
Its outer and front surfaces exhibit several spiral markings like 
those on the inner division. Below, this outer column of bone, which 
is narrow from before*backwards (,%;ths of an inch), suddenly widens 
to nearly #ths of an inch, and presents a semicircular inferior con- 
tour when viewed laterally. Its distal end, in fact, is converted 
into a subcylindrical articular condyle, slightly concave from side to 
side, and having its anterior and posterior faces oblique to the plane 
of the bone and to its transverse axis. It is like a portion of a 
cylinder whose axis is directed upwards, outwards, and backwards, 
so that its inner edge is more prominent anteriorly, its outer edge 
posteriorly, and its inner edge inferiorly. A deep broad cleft, corre- 
sponding in length with the articular surface, separates this condyle 
from a second, developed from the middle of the distal end of the 
bone. This middle condyle is wider than the outer, measuring fully 
half an inch transversely ; it is also deeper, having an antero-posterior 
diameter of fully ?ths of an inch; and it is longer, for, though its 
