THE OSTEOLOGY OF ELOTHERIUM. 311 



quite widely expanded in the transverse direction; and in shape recalls that seen in the 

 camels and llamas. The head is almost hemispherical in form and has a small, deep pit 

 for the round ligament ; it is set upon a very distinct neck, which is connected by a long, 

 narrow bridge of bone with the great trochanter. The latter is very large and massive, 

 especially in the antero-posterior direction, but does not rise above the level of the head, 

 and hence is not very conspicuous, when the femur is seeu from the front. The digital 

 fossa is deep and widely open, which is due to the great thickness of the trochanter, but 

 is not much extended in the vertical direction. The second trochanter is also large and 

 very rugose, but not very prominent ; it projects almost entirely backward, so that the 

 trochanter is hardly visible, when the bone is viewed from the anterior side. There is no 

 plainly marked intertrochanteric ridge, connecting the great and second trochanters, but 

 from the latter a ridge runs proximally and almost reaches to the head. 



The shaft of the femur, which in its proximal portion is much expanded transversely 

 and compressed antero-posteriorly, rapidly narrows downward, and below the second 

 trochanter becomes quite slender and subcylindrical in shape. Toward the distal end 

 the shaft widens considerably, though increasing little in thickness. Above the external 

 condyle is a long, narrow pit, with rugose margins, which serves for the origin of the 

 plantaris muscle. The rotular groove is very broad, but quite shallow ; its inner border 

 is much thicker and more prominent than the outer, and ascends higher proximally, 

 where it terminates in a short, overhanging hook, while the external border dies away 

 more gradually. The condyles are relatively small ; they present directly backward, 

 though not projecting very strongly behind the plane of the shaft, and are of almost 

 equal size, the external one but slightly exceeding the internal in height and breadth. 

 The intercondylar fossa is broad and deep and has nearly straight borders. 



The proportionately small antero-posterior diameter of the distal part of the femur 

 in Elotherium is in decided contrast to the thickness of this region in Ancodus. The 

 femur of Anthracotherium is much like that of Elotherium, but it is even more slender 

 in proportion to its length, and the condyles are smaller. Sus has a femur of quite a 

 different type ; the proximal end is not so wide, the head is more sessile and has a much 

 larger pit for the round ligament ; the bridge connecting the head with the great 

 trochanter is shorter and much thicker, and the trochanter itself is more prominent ; the 

 shaft is relatively less elongate, the rotular groove has borders of nearly equal height, 

 and the condyles are more prominent. The femur of Hippopotamus, though extremely 

 massive, has yet a certain resemblance to that of Elotherium, as may be seen in the 

 transverse expansion of the proximal end and in the obliquity and asymmetry of the 

 rotular groove. 



The patella is large, massive and of rather peculiar shape. It is high, quite broad 



a. p. s. — vol. xix. 2n. 



