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 (i/.) has a rough surface for articulation with the sacrum. 

 Between the pubis (jmh.) in fi-ont and the ischium (iscJi.) behind is 

 a large aperture — the ohlurator fonniien (ohf.). 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- 

 axinl border is internal and the originally dorsal surface anterior. 

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

 Avith 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 

 below the great trochanter. At its 



P-^. 



cal 



cab- 



cisT" 



nau 



\ f?i/n 



a,oei 



Fio. 1085.— Lepus cuniculus. Innominate bones 

 and sacrum, ventral aspect, ucet. acetalnilum ; il. 

 ilium ; isch. ischium ; oht. obturator foramen ; jni.b. 

 pubis ; sacr. sacrum ; sy. symi^bj-sis. 



Fici. lOSO.—Lepus cuniculus. 



Skeleton of pes. ait. astragalus ; 

 cat. calcaneum ; cub. cuboid ; 

 cun. cuneiforms ; nav. navi- 

 cular. 



distal end are two prominences or condyles, with a depression 

 between them. Two small sesamoids or faJjcllK 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 'pcdella. 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 



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