MAMMALIAN FOSSILS FROM DEVIL'S GULCH 185 



seems intermediate between the more typical ancestral forms and 

 the later extreme forms. 



In all, some 5 or 6 tusks of this species were found. They 

 average about 3 feet (915 mm.) in length, and about 3 inches (77 

 mm.) in greatest diameter. The upper tusks curve downward and 

 diverge at the tips, and on the outer side is a relatively broad, 

 flat, enamel band, resting upon the dentine and presenting distinct 

 edges. Each and every tusk from this level shows a similar 

 enamel band. In the case of one or two tusks, the band has 

 become almost vestigial, and represents an interesting transitory 

 stage. In one example, the enamel band is about an inch broad 

 near the tips. It rests upon, and well above, the dentine, and 

 presents distinct edges. It narrows posteriorly to a fourth of an 

 inch, and its edges become imbedded in the dentine of the tusk. 

 Near the alveolus, it sinks somewhat into the dentine. 



The teeth are trilophodont. Those of the upper jaw are four 

 in number, of the lower, three. All of the " Tetrabelodon " teeth 

 found on this level seem to be small. In the upper molars, the 

 outer tubercles are long and conical, with light cingulum, and with 

 no secondary cones to fill the valleys. On the inner side, how- 

 ever, the tubercles are crowded with secondary cones, the valleys 

 obstructed, and the cingulum strong and serrated by conelets. 



The mandible is in a state of perfect preservation. Its length 

 is 30 inches (762 mm.) and the extreme width across the con- 

 dyles is 14^-2 inches (368 mm.). It is but slightly decurved, and 

 has a deep lingual groove with sharp edges. The mandibular 

 border rounds into the ascending ramus without angle. The 

 ascending ramus is strong and relatively high. The condyle has 

 a distinct neck, and stands 4 inches (102 mm.) above the grinding 

 surface of the molars. The sigmoid notch is deep, and the coro- 

 noid high and prominent. It resembles the typical coronoid more 

 closely than does any proboscidean with \vhich the writer is 

 familiar. The symphysial prolongation is 9 inches (230 mm.). 

 Two strong mandibular tusks project 4 inches (102 mm.) from 

 the jaw, and are i-Hs inches (42 mm.) through. They are worn 

 obliquely at the tips, as shown in the accompanying cuts. The 



