THE MUSCULAR ANATOMY AND THE RESTORATION OF THE TITANOTHERES 



719 



shaped vastus of the horse and kangaroo contributes 

 to the far greater saltatorial power. 



On the front face of the femur the massive but low 

 great trochanter gave attachment to the gluteus 

 medius. The region between the great trochanter and 

 the head is widened and exhibits laterally the upper 

 limits of the area for the vastus externus; in the mid- 

 line is a roughened line separating the area of the 

 vastus externus from that of the vastus internus, as 

 in Tapirus. The area for the vastus externus (which 

 in Tapirus was probably a very large muscle covering 

 the entire length of the shaft of the femur) is 

 not visibly separated below from the area for the 

 crureus, which probably covered 

 the front and lower outer part of 

 the shaft. 



Outer edge of the femur: The 

 great trochanter bears on its upper 

 and external faces the area for 

 the gluteus medius. The third 

 trochanter bounds externally the 

 area for the vastus externus and 

 on its outer crest gives insertion 

 to the deep slip of the gluteus 

 maximus; the low ridge leading 

 down from the third trochanter 

 to the shaft may also have given 

 insertion to fibers of the gluteus 

 maximus. 



About 3 inches above the 

 ectocondyle is the ridge for the 

 external head of the gastroc- 

 nemius. Immediately below the 

 gastrocnemius ridge is the deep 

 plantar fossa facing postero- 

 externally and giving origin to 

 the tendon of the plantaris (flexor 

 sublimis). 



The external tuberosity of the 

 femur (above the ectocondyle) 

 bears on its outer face a deep pit 

 for the collateral femoro tibial 

 ligament. Lying between the 

 last-named pit and the patellar 

 trochlea is the pit for the tendon of the extensor 

 longus digitorum, while behind this in turn and 

 above the condylar surface is a circular deep pit 

 for the tendon of the popliteus. (Possibly also the 

 femoral portion of the peroneus longus may have 

 arisen here. Compare Windle and Parsons, 1901.1, 

 p. 278.) 



The posterior surface of the femur shows especially 

 the following structures: (1) The great trochanter, 

 bearing the posterior portion of the area for the gluteus 

 medius; (2) the digital or trochanteric fossa, lodging 

 the obturator internus, gemeUi, and obturator externus ; 

 the quadratus femoris may have been inserted below 



these; (3) the second trochanter (trochanter minor), 

 giving insertion both to the psoas and to the iliacus; 



(4) the third trochanter, for the gluteus maximus; 



(5) the area for the pectineus, lying toward the inner 

 border and some distance below the second trochanter. 

 A foramen for a branch of the femoral artery lies below 

 the last-named area and in about the middle of the 

 internal posterior edge of the femur. (6) The linea 

 aspera (plainly shown in the femur, Am. Mus. 11690) 

 lies in the middle third of the posterior face of the 

 femur near the internal border and below the area for 

 the pectineus; in this region bounded by the linea 

 aspera internally and by the downward prolongation 



A3 

 FiGUKE 657. — Left femur of Broniops robushis (type), showing probable position and 

 attachments of principal muscles 

 Ai, Front view; A2, inner side view; Aj, back view. One-eighth natui-al size. 



of the third trochanter the adductor longus was prob- 

 ably inserted. 



Inner face of the femur: The principal topographic 

 features of the inner face of the femur are as follows: 

 (1) The pit for the ligamentum teres; (2) the promi- 

 nent second trochanter, roughened for the attachment 

 of the iliacus and psoas; (3) the area for the vastus 

 internus along the inner shaft; (4) the foramen for the 

 femoral artery; (5) near the lower end the area for 

 the internal head of the gastrocnemius; (6) above the 

 internal condyle a vertical ridge for the adductor and 

 semimembranosus; (7) below this the pit for the liga- 

 mentum collaterale' laterale. 



