194 ON THE EXTINCT MAMMALIA OF 



and those of the two premolars in advance. The upper part and sides of the face 

 together form rather more than a half-cylinder, widening somewhat conically behind. 

 Measurements derived from the specimen are as follow : 



Lines. 



Length of space occupied by the closed row of teeth, consisting of the true 



molars and the two premolars in advance, about . . .68 



Space occupied by true molars, about . . . . .40 



Height of face at middle on line of interval between last two molars, . 40 



Distance between infra-orbital foramina, . . . . .32 



An upper canine tooth, broken at the ends and worn oflf in front, at the conjunction 

 of the crown and fang, into a vertical elliptical plane an inch and a half long and 

 seven lines wide, also apparently belongs to the larger Motherium.. The fang is 

 somewhat gibbous at its widest part antero-posteriorly, measuring sixteen lines fore 

 and aft and eleven lines transversely. The length of the tooth in its perfect state, 

 along the anterior curve, has been about six inches ; the crown alone about two and 

 a half inches. 



A still larger species of Eloihermm than either of the preceding is perhaps indicated 

 by the greater portion of a canine tooth, obtained by Dr. Hayden with the preceding 

 specimens. It appears to have belonged to the left side of the lower jaw. Both ends 

 of the tooth and the inner side of the crown are broken away. The remaining por- 

 tion of the crown exhibits the effects of attrition of the opposed teeth, both before and 

 behind. The gibbous fang is an inch and a half in diameter antero-posteriorly, and 

 rather less than an inch and a quarter transversely. In the perfect condition the 

 tooth has probably measured about seven inches in length along its anterior 

 curvature. 



The difference of size between certain specimens of Elotheriwm is so great as to 

 leave little doubt that they indicate at least two distinct species, but between the 

 extreme sizes there are many gradations, which probably relate to different sexes. 

 The tooth just described may have been that of an old male of U. ingens, or, as above 

 intimated, it may indicate a third species of the genus. 



PERCHCERUS. 



Perch(ert:s probus. 



Among the fossils of the Mauvaises Terres collections there are a few small frag- 

 ments of jaws with teeth and isolated teeth of suilline animals, which, especially from 

 the paucity of material, are of uncertain reference. I have referred them to two new 



