88 The Alligator and Its Allies 
The tarsus is much modified and consists of 
four elements, in two rows; those of the proximal 
row are much larger than the two distal elements. 
Articulating with both tibia and fibula, as men- 
tioned above, and with the first metatarsal and 
one of the distal tarsalia, is the large and irregular 
tibiale-centrale element of Reynolds (tb, th’). 
In the tarsus here shown it consists of two elements. 
Post-axial in position is the calcaneum or fibulare 
(ca), articulating with the preceding tarsal element, 
with the fibula, with the rudimentary fifth meta- 
tarsal, and with the distal tarsal element said by 
Reynolds to represent the fourth and fifth tarsa- 
lia. The calcaneum is extended caudad into a 
prominent knob quite like the heel of the higher 
mammals. 
The two distal tarsal bones are small; one is 
said by Reynolds to represent the first three tarsalia 
(t3), the other (t**) the fourth and fifth. Wieders- 
heim says one of these bones represents the first 
three tarsalia, the other the fourth. In the tarsus 
here shown these two elements are fused. 
The foot has five digits, though the fifth is small 
and consists merely of a small, distally pointed 
metatarsal bone. According to Wiedersheim this 
fifth metatarsal is fused with the fifth tarsalia. 
The metatarsals of the first four digits are long and 
progressively more slender from the first to the 
fourth; each is distinctly enlarged at the ends. 
The first digit or hallux has two phalanges, the 
