48 DESCRIPTION OF THE SKELETON. 



generally smooth, rounded, and not prominent; an anterior, rough above, 

 sharp and well defined in the middle, dividing into two lines below, to 

 terminate in the malleolus externus ; a posterior, rough and well defined, 

 extending from the posterior face to the back part of the malleolus (Plates 

 XIII. and XIV. B). The internal face of the bone is irregularly flattened; 

 the posterior is narrow, of small extent, and ill defined ; the external face 

 is rounded above, flattened and somewhat excavated below. 



The malleolus is grooved posteriorly : internally it presents an irregular 

 surface, composed of three parts, viz. the first, anterior, rough for ligamentary 

 attachment ; the second, internal and superior, smooth for the tibial attach- 

 ment ; the third, below, excavated for the os calcis. The external surface 

 of the malleolus is distinctly divided into two portions ; the anterior most 

 extensive, the posterior smooth and excavated for the passage of the pero- 

 neus longus muscle. 



The whole length of the fibula is twenty-six inches ; the circumference 

 of the middle of the shaft, six inches and a quarter. The inferior extremity 

 of the malleolus externus is much the broadest part of this bone, measuring 

 seven inches in diameter. 

 The Foot. The Foot. — The foot of the Mastodon is much depressed, compared 



with that of the elephant. It presents a superior regular convex surface ; 

 and an inferior, irregularly excavated. Taking the tuberosity of the os 

 calcis with the projection of the five toes, the surface may be said to have 

 a radiated form. 

 Tarsus. Tarsus. — It is composed of seven bones, placed in two ranges ; all of 



them flatter than in the elephant, 

 First First Eaxge. Astragalus (Plates XIII. and XI V. C). — The astragalus 



Range. 



is quite a flattened bone, compared with that of man, or even with that of 



