164 



THE OSTEOLOGY OF THE REPTILES 



ing below the middle, there is, especially in crawling forms, a rugosity 

 or eminence, the lesser trochanter,^ from which usually a more or less 

 pronounced ridge or roughening descends toward, or nearly to, the 

 postaxial condyle (Figs. 129 b, 132). It corresponds to the linea 

 aspera of mammals and may be called the adductor ridge or crest. 

 On the opposite side, and nearer the head, obsolete or even absent 

 in ordinary crawling reptiles but well devel- 

 oped in the Chelonia (Fig. 1 54) [and in certain 

 Therapsida, Fig. 132], is the great trochanter. 

 Between the two there is a depression or fossa 

 [intertrochanteric], at the upper extremity in 

 turtles (Fig. 154), but broadly ventral in most 

 other forms. 



The femora of the dinosaurs (Fig. 132 bis)^ 

 especially the bipedal Predentata, but also in- 

 dicated in the Sauropoda, have near the 

 middle on the ventral preaxial side a rugosity 

 or prominence, the fourth trochanter, sometimes, 

 as in Camptosaurus, long and pendent. 



The condyles, at the distal extremity of the 

 femur, are separated by a groove in front and 

 another behind (Fig. 129 b). The preaxial 

 condyle, usually the smaller, gives articulation 

 to the tibia; the postaxial condyle, to the fib- 

 ula, and in part to the tibia behind. The 

 shaft of the femur is sometimes markedly 

 curved (Figs. 155, 157), sigmoidally in the 

 more slender kinds. It is always longer and 

 Fig. 132 bis. Dinosaur femur: niore sleudcr than the humerus, its distal 



Camptosaurus, right femur. • i i i t 



After Giimore. One sixth Width scMom if ever equal to more than half 

 ""*""' ^■"- the length of the bone. 



The femur of the temnospondylous amphibians (Fig. 151 a) is 

 sometimes indistinguishable from that of the cotylosaurs, but usu- 

 ally the adductor ridge is more strongly developed, and the articular 

 ends are less well ossified. 



1 [Recent evidence (Romer, 1924) indicates that this process is not homologous 

 with the true "lesser trochanter" of mammals. A better name for it is "internal tro- 

 chanter." — Ed.] 



