654 S. W. WILLISTON 
distal row, a number found by Baur in Archegosaurus, but otherwise 
unknown among air-breathing vertebrates. Of the proximal row the 
tibiale is elongate, a little broader proximally, with a thickened, 
rounded internal margin, articulating proximally. with the tibia, 
distally with the first centrale, and internally with the second and third 
centralia. The intermedium is large, with a thickened, oblique face 
for union with the fibula proximally, a free rounded border opposite 
the distal part of the tibia, articulating distally with the large centrale, 
and externally with the fibulare, leaving, however, a small opening 
for the passage of vessels. The fibulare is elongate antero-posteriorly, 
and is rather broad; it articulates proximally, on the upper side, with 
the fibula, internally, above, with the intermedium, distally with the 
fourth and fifth distalia, and between them and the intermedium 
with the large centrale. The proximal centrale is one of the largest 
bones of the tarsus; it is somewhat broader on the inner than on the 
outer end, articulating proximally with the intermedium, internally 
with the tibiale, externally with the fibulare, and distally with the two 
outer centralia. The innermost of these is the smallest, articulating 
between the tibiale and the first distal, and, on the outer side, with 
another centrale. This is an unusual position for a centrale, and I 
have endeavored to find in the small bone some evidence of extraneous 
origin, but am quite convinced that it really belongs in this place, as 
otherwise the space it occupies must have been unossified. ‘The 
median distal centrale is the largest of the three distal centralia, and 
is nearly square in outline; it articulates proximally with the tibiale 
and proximal centrale, on either side with a centrale, and distally 
with the second distal. Of the distal, the second is the largest and 
the fifth is the smallest, the third and fourth smaller than the second. 
Each distal supports its own digit exclusively. 
The digits are, it is seen by the figure and the restoration, very 
short and heavy. ‘The first metatarsal is very characteristic in its 
broad and short form, resembling more a proximal phalanx, broadly 
expanded proximally and much constricted in the middle. At its 
distal extremity there is a fragment of the first phalanx in articulation, 
the remainder lost. The width of this fragment would indicate the 
possibility of a second phalanx of very small size. The second 
metatarsal is much longer than the first, its proximal extremity less 
