SKELETON OF MONOTREMATA. 



327 



of the pubis from the symphysis outward to that of the spinous 

 process : they are relatively longer in the Echidna than in the 

 Ornithorhynchus ; they always remain moveably articulated with 

 the brim of the pelvis. 



The femur, fig. 199, 65, is short, broad, and flattened ; its head 

 rises, like that of the humerus, from the middle of a broad ex- 

 panded proximal end, having on each side a strong process, the 

 outer one representing the great, the inner one the small, tro- 

 chanter. In the Echidna a projecting ridge extends from the 

 great or outer trochanter beyond the middle of the bone ; the 

 whole of the inner part of the shaft is bounded by a trenchant 

 edge ; both outer and inner margins of the bone are trenchant in 

 the Ornithorhynchus. The distal end of the femur is expanded 

 transversely, but compressed from before backward. The rotular 

 trochlea is flat transversely, convex vertically, in the Echidna ; it 

 is hardly definable when the cartilage is separated from the bone ; 

 but the patella itself is well developed, and ossified in both 

 Monotremes, fig. 199, />. 



The tibia, ib. 66, is straight in the Echidna, but bent, with the 

 convexity next the fibula, in the Ornithorhynchus ; its cristoe are 

 slightly marked. 



209 



The fibula is slightly bent 

 in the Echidna, fig. 201, 67, 

 but is straight in the Orni- 

 thorhynchus, fig. 199, 67 ; in 

 both Monotremes it is longer 

 than the tibia by the extent 

 of a process, ib. v, which 

 rises upward beyond the 

 proximal articulation of the 

 fibula, and strongly expresses 

 the homotypal relation of 

 this bone with the ulna: 

 this process reaches halfway 

 up the back of the femur in 

 the Ornithorhynchus, and, 

 like the olecranon, is greatly 

 expanded at its termination. 



The tarsus, figs. 209, 210, 

 consists of a naviculare, a, 

 astragalus, b, a calcaneum, c, 

 three cuneiform bones, d, e, f, and a cuboid, g, in the Echidna ; 

 but the cuboid in the Ornithorhynchus is divided into two bones. 



Bones and claws of tlie liind-foot, rotular aspect, 

 Echidna. 



