

FOSSIL MAMMALIA. 49 



of bone which is continued from the under part of the head of the femur to the 

 inner surface of the shaft. In the Palgeothere the lesser trochanter is situated 

 more towards the posterior surface of the femur ; so that, in this particular, the 

 Macrauchene approaches nearer to the Camel. Cuvier makes no mention of the 

 condition of the depression for the ligamentum teres in the Palseothere. Among 

 existing ordinary Pachyderms the Hippopotamus presents no trace of the inser- 

 tion of a ligamentum teres in the head of the femur ; in the Camel the place of 

 its insertion is indicated by a well-marked circumscribed pit; in the Tapir a 

 similar circular depression is situated close to the inferior margin of the articular 

 convexity. The ligament was undoubtedly present in Macrauchenia, but the 

 place of its insertion is a broad and deep notch leading from the under and back 

 part of the head of the bone a little way into its articular surface : this I regard 

 as another of those interesting transitional structures with which the remains of 

 the Macrauchenia, few and imperfect though they unfortunately are, so freely 

 abound. 



The femur of Macrauchenia, in the flatness of the back part of its neck, and 

 the elongated form of the post-trochanterian depression, resembles that of the 

 Camel rather than that of the Palseothere ; and the same resemblance is shown in 

 the cylindrical figure, straightness, and length of the shaft. The depth of the tro- 

 chanterian depression, and the incurvation of the strong ridge continued down- 

 wards from the great trochanter are individual peculiarities in the Macrauchenia. 

 A great part of the third trochanter is broken off; but from the remains of 

 its base we see that it had the same relative size as in the Palseothere ; but it is 

 situated at the middle of the shaft of the femur, and consequently lower down 

 than in the Palseotheres and Tapirs. In the general form and relative size of 

 the condyles at the distal extremity of the femur (fig. 3, PI. IX. and XII.) the 

 Macrauchene is intermediate to the Camel and Palseothere, but resembles more 

 the latter. In the articular surface for th~ patella, it deviates somewhat from 

 the Palseothere, having this part longer in proportion to its breadth, more regu- 

 larly and deeply concave from side to side, and with its lateral boundaries more 

 sharply defined. In all these points the Macrauchene approaches the Camel : the 

 same affinity is shown in the protuberance above the inner condyle ; but in the 

 extent of the posterior projection of this condyle (fig. 3, PI. IX.) it exceeds the 

 Camel and Palseothere, and displays an intermediate structure between these 

 species and the Hippopotamus. 



There is a rough crescentic depression above the outer condyle where the 

 linea aspera begins to diverge ; the corresponding depression is deeper in the 

 Hippopotamus, while in the Camel it is represented by a roughened surface only, 

 which is not depressed. In the fossa between the rotular articulation and the 

 external condyle the Macrauchene resembles the Camel : the interspace of the 



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