52 GENERAL ANATOMICAL CHARACTERS 
aspect of the shaft of this bone in many forms is of considerable 
taxonomic importance. 
Pes,—The terminal segment of the hind limb is the foot or pes. 
Its skeleton presents in many particulars a close resemblance to that 
of the manus, being divisible into three parts: (1) a group of 
short, more or less rounded or square bones, constituting the 
tarsus ; (2) a series of long bones placed side by side, forming the 
metatarsus ; and (3) the phalanges of the digits or toes. 
The bones of the tarsus of many of the lower Vertebrata closely 
resemble both in number and arrangement those of the carpus, as 
shown in Fig. 17. They have been described in their most general- 
ised condition by Gegenbaur under the names expressed in the first 
column of the following table. The names in the second column are 
those by which they are generally known to English anatomists, 
while in the third column some synonyms occasionally employed 
are added. 
ene) = \ = Astragalus 1 = Talus. 
Fibulare = Calcaneum = 0s calcis. 
Centrale = Navicular = Scaphoideum. 
Tarsale 1 = Internal cuneiform = Entocunetforme. 
Tarsale 2 = Middle cuneiform = Mesocunetforme. 
Tarsale 3 = External cuneiform = Ectocunetforme. 
Tarsale 4 ! 
Tarsale 5 \ = Cubeid. 
The bones of the tarsus of mammals present fewer diversities of 
number and arrangement than those of the carpus. The proximal 
row (see Fig. 18) always consists of two bones, namely the astra- 
galus (a), which probably represents the coalesced scaphoid and lunar 
of the hand, and the caleaneum (c). The former is placed more to 
the dorsal side of the foot than the latter, and almost exclusively 
furnishes the tarsal part of the tibio-tarsal or ankle-joint. The cal- 
caneum, placed more to the ventral or “plantar” side of the foot, is 
elongated backwards to form a more or less prominent tuberosity, 
the “tuber calcis,” to which the tendon of the great extensor muscles 
of the foot is attached. The navicular bone (n) is interposed between 
the proximal and distal row on the inner or tibial side of the foot, 
but on the outer side the bones of the two rows come into contact. 
The distal row, when complete, consists of four bones, which, be- 
ginning on the inner side, are the three cuneiform bones, internal 
(c), middle (¢?), and external (c*), articulated to the distal surface 
of the navicular, and the cuboid (cb), articulated with the calcaneum. 
Of these the middle cuneiform is usually the smallest in animals 
1 Cope and Baur consider that the astragalus corresponds only with the inter- 
medium, and that the tibiale may exist as a distinct element. 
