EXTINCT MAMMALIA OF NORTH AMERICA. 409 



of a fossil jaw, found in a miocene formation of Sansan, France, and referred to an 

 insectivorous animal with the name of Galerix viveroides. The extremities of the 

 ramus are lost, and the remaining portion contains four molar teeth. The depth of 

 the jaw below the position of the latter measures about two lines, and is nearly uni- 

 form. The base is but slightly convex fore and aft, below the position of the teeth. 

 Back of these to the broken end of the specimen it is slightly concave. The mental 

 foramen is below the position of the second premolar, and the symphysial articulation 

 reached as far back as the third. The masseteric impression is well marked, and 

 well defined about two lines back of the position of the second true molar. 



Seven molar teeth, in an unbroken series, appear to have occupied the side of the 

 jaw. Four appear to have been double-fanged premolars, with laterally compressed 

 conical crowns. Only the third and fourth of the latter are preserved. The alveoli 

 of the second are retained, and also the inner side of what appears to be a pair for the 

 first premolar. 



The last true molar, which has lost its crown in the specimen, appears to have 

 been a double-fanged tooth, constructed like those in advance. 



The teeth in the specimen from the third premolar to the second true molar suc- 

 cessively, and after the former, gradually decline in height or prominence. 



The third and fourth premolars nearly resemble in general form and proportions 

 the second and third premolars of the Opossums. The true molars are constructed 

 on the same general pattern as those of the genera Sorex, Erinaceus, Gyinnura, Po(o- 

 mogale, Oaleopithecus, and the Opossums. All the teeth are provided externally with 

 a basal cingulum or ridge, nowhere elevated into points or cusps. 



The crown of the third premolar, more prominent than in any other tooth, is tri- 

 angular, longer than broad, pointed, and thicker posteriorly. Its anterior border is 

 acute and slightly convex in the length ; the posterior outline, formed by the back 

 part of the outer convex surface, is slightly concave. The inner surface, narrower 

 than the outer, presents at its fore part below a narrow ledge, feebly continuous for- 

 ward, as an element of the basal cingulum. This is best developed as a talon at the 

 back of the crown, and least externally and postero-internally. The outer surface of 

 the crown, convex transversely, is continuous posteriorly. 



; The fourth premolar has nearly the same form as the preceding tooth, but its 

 crown is lower and wider. Tlie basal cingulum is rather better developed externally 

 and less so antero-internally. The inner surface is sensibly concave, and the ridge 

 defining it from the postero-external surface exhibits a feeble tendency to form an 

 accessory point. 



The crowns of the two succeeding true molars, retained in the specimen, are nearly 

 alike in size and form, though the first is in a tritling degree wider and higher. They 

 are bounded by a well marked basal cingulum externally, nearly half their depth. 



