198 ON THE EXTINCT MAMMALIA OF 



The fossil evidently indicates a small suilline animal, for which the above name 

 has been proposed. It was about the size of its ancestral relations of the same family, 

 the Hyrucotherium cmiiculus and Microchoerus erinaceus, of the English eocene 

 formation. 



The molar teeth of the fossil resemble in form the corresponding ones of the 

 Peccary, being oblong-square viewed laterally, and oblong-square, with rounded 

 angles and a median constriction, when viewed above. A basal ridge exactly as in 

 the Peccary holds the same relation with the crown. 



Figure 16, plate XXI, represents an upper view of the first molar, magnified three 

 diameters. The second molar has the same form, but is smaller, — an unusual 

 condition among the known suilline animals. The teeth belong to the left side, so 

 that the left portion of the figure is the anterior of the tooth, and the upper portion 

 the inner side of the same. The crown, viewed from the inner and outer side, 

 exhibits the antero-internal division of the crown as the largest, the contiguous outer 

 division next in size, and the postero-internal division as the smallest. Viewed from 

 the triturating surface, the postero-external eminence or lobe Avith its divergent arms 

 appears the largest, though corresponding with the division of the crown which is 

 third in size. A basal ridge exists in front and behind the crown, and an element of 

 the same occuj^ies the bottom of the interval of the external eminences. The lobes 

 of the crown are conoidal, and the external ones have crescentoid summits. Those 

 of the back lobe diverge in a V-like manner to the inner lobes ; those of the fore 

 lobe curve inwardly to join the antero-internal lobe. The sides of the crown are, 

 relatively with the size, strongly corrugated. 



The specimen above described is the only one which could with any degree of 

 certainty be referred to Leptochcems spectabilis. Its measurements are as follow : 



Lines. 



Thickness of jaw below first true molar, . . . . . 3i 



Antero-posterior diameter of do.. 

 Transverse diameter of do., 

 Antero-posterior diameter of second true molar. 

 Transverse " " " 



21 

 2i 

 2i 

 2 



Dr. Hayden's collection of the summer of 1866 contains two additional specimens 

 from the Mauvaises Terres of White River, which appear to be referable to Lepto- 

 chcerua spectabilis. One of them consists of a fragment of the right side of the lower 

 jaw, containing the second and third premolars, a portion of the fourth one, and the 

 first true molar. The other specimen is a fragment of the same side of the upper 

 jaw, containing the last premolar and the following pair of true molars. 



The specimen of the lower jaw is represented in figure 17, plate XXI, of thfe 



