184 ON THE EXTINCT MAMMALIA OF 



In a young unworn first upper premolar, contained in a fragment of an upper jaw, 

 the crown is strongly curved, and its posterior and antero-internal subacute indented 

 ridges give it a decidedly carnivorous reptilian look. 



Of the lower premolars the first is the smallest and the third the largest. All four 

 have crowns resembling the anterior three upper ones, except that the last of the 

 series has the base of its crown extended into a broad heel, festooned by a narrow 

 basal ridge. The same tooth has a similar ridge at its fore-part, and feebler ridges of 

 the same character festoon the fore and back part of the bases of the teeth in advance. 



The fourth lower premolar is close to the succeeding true molar, the third is close 

 to the former or separated by a narrow interval ; the others are separated from the 

 latter and each other, and from the lower canine by more or less wide intervals. 



The canine teeth of Elothermm Mortoni resemble much more those of carnivorous 

 animals than of any existing pachyderms. They especially resemble those of the 

 Bear. Their crown is long, conical and curved. They end in an obtuse point and 

 posteriorly present a subacute ridge, separating the outer and inner surfaces. Antero- 

 internally also they present a less prominent, shorter and more obtuse ridge. The 

 fangs pursue the same course, as in the Bear, and have the same conical gibbous 

 character. 



The upper and lower canines are nearly equal in size, but the excess is in favor of 

 the former. 



The incisors, three in number, on each side, above and below, increase in size in 

 succession from first to last. They are separated from one another by considerable 

 intervals, and those above are separated from the contiguous canine by a larger 

 interval, to accommodate the point of the canine below. 



The fangs of the incisors curve from their sockets in the same manner as those of 

 the canines. The crowns are curved conical, and have their outer more convex 

 surface defined from that within by lateral subacute ridges, most prominent at the 

 base of the crowns. 



When the jaws are closed the lobes of the true molars, above and below, alternate 

 with one another, the latter holding the advanced position. The crowns of the lower 

 premolars and the lower canine are situated in advance, and interlock with those 

 above. The incisors of the two sides together form semicircular rows. 



The enamel on all the teeth is thick and strongly corrugated, but is especially 

 rugged upon the true molars. The ridges of the crowns, wherever they exist, are 

 more or less indented. 



Temporary dentition. — The number of temporary teeth and the order of succession 

 of the permanent series, appears to have been the same in Elotherium Mortoni as in 

 the Hog. 



