NO. 2 EXTINCT HORSE FROM ALASKA— HAY 1 3 



The catalogue number, 2645, in the U. S. National Museum, be- 

 longs to a lot of four lower teeth, which were collected by Mr. A. G. 

 Maddren for the museum in 1904, on the Old Crow River, in Yukon 

 Territory, not far from the boundary line between this territory and 

 Alaska (fig. I (12)). 



It seems probable that three of these teeth belonged to one indi- 

 vidual, the fourth to another and much younger one. The three are 

 represented by figs. 5-7, the fourth tooth by fig. 8. One of the three 

 (fig. 5) is the second premolar, another (fig. 7) the third molar, the 

 other (fig. 6) probably the first molar; and all belonged to the left 

 side of the lower jaw. The following are the dimensions of these 

 teeth : 



Measurements 



Pm.2, height 53 



length 38 



width 17.5 



M.i, height 56 



length 30 



width 17 



M.s, height 65 



length 33-5 



width 14 



On comparing the figure of pm. 2 (fig. 5) with that of the same 

 tooth of the type of Equus niobrarensis (Proc. U. S. Nat. Mus., 

 Vol. 44, p. 579, fig. 20) it will be seen that the Alaskan tooth is broader 

 and has somewhat more complicated enamel. The supposed first 

 molar (fig. 6) differs from that of the type of Equus niobrarensis in 

 having slightly more complicated enamel bands, but especially in 

 having the valley which enters the tooth from the outside pushed 

 between the two longitudinal valleys and nearly to the enamel of 

 the opposite side. In about the same way the last molar (fig. 7) 

 differs from that of the Niobrara horse. It does not appear probable 

 that these teeth belonged to Equus niobrarensis alaskce. 



The fourth tooth (fig. 8) evidently belonged to a younger horse, 

 having been worn down very little. It is considerably damaged, but 

 the essentials of its structure can be made out. The height of the 

 tooth is 82 mm.; the length is about 34 mm.; the width, 11 mm. 

 The drawing will show the extreme complication of the enamel. It 

 is probable that it is the tooth of a third Alaskan species. 



During the summer of 1912 Mr. Copely Amory, Jr., made a small 

 collection of fossil mammal bones on the Old Crow River, about fifty 

 miles above its mouth. Among the animals represented are the 

 mammoth, bison, a camel, and one or more horses. The horse 



