64 PROCEEDINGS OF THE ACADEMY OF 



Gervais, Peters, Mivart, and others, the jaw fragment approaches most 

 nearly in size and form the corresponding portion in the representations 

 of Tupaia ferruginea^ of Java and neighboring isles. It likewise nearly 

 resembles in size and form the corresponding portion 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 

 uniform. 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 con- 

 cave. 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 pre- 

 served. 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 

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

 The third and fourth premolars nearly resemble in general form and propor- 

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

 constructed on the same general pattern as those of the genera Sorex, Erina- 

 ceus, Gymnura, Potomogale, Galeopithecus, 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 triangular, 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 forward 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. The basal cingulum is rather better developed 

 externally and less so antero-internaliy. The inner surface is sensibly con- 

 cave, 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 trifling degree wider 

 and higher. They are bounded by a well marked basal cingulum externally, 

 nearly half their depth, reaching across the median valley and also anteriorly, 

 but ceasing and becoming obsolete behind. 



Two cusps or lobes project at the outer part of the crown of the true mo- 

 lars, and three smaller ones internally. Of the outer cusps the anterior is the 

 higher and narrower. Of the inner ones the posterior two are nearly equal and 

 the anterior is the smallest; most so in the second molar. They are all three- 

 sided pyramids, each with one face directed inwardly and two outwardly. 

 Their height is not greater than their width, nor are tliey very sharply pointed. 

 The borders defining the inner surface of theantero-external cusps conjoin the 

 antero-internal two cusps, including a small depression. Of the borders defin- 

 ing the inner concave surface of the postero-external cusp, the front one joins 

 the posterior surface of the antero-external cusp, while the back one joins 

 the postero-internal cusp. 



[April, 



