8 PEOCEEDINGS OF THE NATIONAL. MUSEUM vol. 68 



the crests are slightly worn, the dentine being exposed on the outer 

 ends of the fii*st and second crests. The first valley is widely open, 

 the buttress on the outer half of the crests being feebly developed. 

 The second valley is partially blocked by the meeting of the but- 

 tress descending on the rear of the second crest and that on the 

 front of the third. There is also a buttress on the front of the outer 

 half of the third crest. At the front end of the crown is a distinct 

 talon, but it is not prolonged into a cingulum on the sides. At the 

 rear is a more considerable talon bearing four tubercles. On the 

 front end of the crown is a polished area 15 mm. wide, where the 

 tooth pressed against the hindmost milk molar. No pressure area 

 is seen on the hinder end. The root consists of two fangs (pi. 4, 

 fig. 2) the anterior of which supported the first crest; the second, 

 the other two crests. Near its base the hinder root is 28 mm. wide. 

 In the space between the front and the rear fangs of the right tooth 

 is a fragment of bone 18 mm. high, 20 mm. fore and aft, and 17 mm. 

 from side to side. If there was below this a fourth premolar, its 

 summit must have lain at least 18 mm. below the crown of the milk 

 molar or well at one side of the nodule of bone. 



The upper right second molar presents a nearly perfect crown, 

 lacking only a fragment of enamel on the outer cone of the second 

 crest. Evidently this was splintered off during the life of the animal. 

 The roots are broken off near their bases. The crown is well worn 

 on the fii*st and the second crests, only moderately so on the third 

 (pi. 3, fig. 4). The length is 106 mm.; the width at all of the crests 

 is 66 mm. On the inner ends both the first and the second valleys "are 

 obstructed by the strong buttresses of the rear and of the front of the 

 inner cones. The wear of the main cones and the buttresses pro- 

 duces trefoils. There are mere traces of inner buttresses and there are 

 no subsidiary cusps or conules produced in the valleys. There is 

 present, on the inner face of the crown, a heavy tuberculated 

 cingulum, which is carried around both the front and rear ends of the 

 crown. On the outer face are hardly any traces of this cingulum. 

 There are large polished pressure areas on both ends of the crown, 

 that on the hinder fitting accurately against the third molar. There 

 is in patches a thin layer of cement. The roots are disposed as is 

 usual in the mastodons (text-fig. 1). One fang supports the outer 

 end of the first crest; an inner fang supports the inner ends of the 

 first and second crests; while a third supports the inner end of the 

 third crest and the outer ends of the second and third. 



The crown of the upper third molar lacks no part (pi. 3, fig. 5), 

 but the roots are broken off near their bases. The crown is 136 mm. 

 long and 73 mm. wide at the front crest. The height of the outer 

 cone of the second crest is 50 mm., measured from the base of the 

 crown. Only the summits of the cones of the first crest are woin, 

 and these slightly. Evidently the tooth abutted against the second 



