XIII 



PHYLUM CHORDATA 



457 



the femur, but the remainder of the cavity is bounded, not by the 

 pubis, but by a small intercalated ossification the cotyloid bone. 

 The ilium (il.) has a rough surface for articulation with the sacrum. 

 Between the pubis (pubJ) in front and the ischium (iscA.) behind is 

 a large aperture the obturator foramen (obtJ). The femur is 

 rotated forwards when compared with that of the Lizard, so that 

 the limb is nearly in the same plane as the fore-limb, and the pre- 

 axial border is internal and the originally dorsal surface anterior. 

 The femur has at its proximal end a prominent head for articulation 

 with the acetabulum ; external to this a prominent process the 

 great trochanter, and internally a much 

 smaller the lesser trochanter, while a 

 small process or third trochanter is 



situated on the outer border a little Fi^i r 



below the great trochanter. At its 



curt 



FIG. 1085. Lepus cuniculus. Innominate bones 

 and sacrum, ventral aspect, acet. acetabulum ; il. 

 ilium ; isclt. ischium ; obt. obturator foramen ; pub. 

 pubis ; Kitrr. sacrum; sy. symphysis. 



IV Jff 



FIG. 1080. Lepus cuniculus. 

 Skeleton of pes. ast. astragalus ; 

 col. calcaneum ; cub. cuboid ; 

 cun. cuneiforms ; nav. navi- 

 cular. 



distal end are two prominences or condyles, with a depression 

 between them. Two small sesamoids or fcibellce are situated 

 opposite the distal end on its posterior aspect ; and opposite the 

 knee-joint, or articulation between the femur and the tibia, is a 

 larger bone of similar character the knee-cap or patella. The tibia 

 has at its proximal end two articular surfaces for the condyles of the 

 femur ; distally it has also two articular surfaces, one, internal, for 

 the astragalus, the other for the calcaneum. The fibula is a slender 

 bone which becomes completely fused distally with the tibia. 



The tarsus (Fig. 1086) consists of six bones of irregular shape, 

 VOL. II F F 



