394 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 40. 



crown whose length was 47 mm., width 32 nmi., and height 25 mm. 

 It was composed of seven columns. The front and middle trans- 

 verse rows had two each; the hinder row tliree, of which one is small. 

 It will be observed that the length of the crowns of these two premo- 

 lars taken together amounts to 79 mm. Opposed to these in the upper 

 jaw the Japanese investigators found but one premolar, having only 

 four columns and a grinding surface about 23 mm. long. Because of 

 the state of wear on the hinder lower premolar they assumed the 

 presence of another upper premolar; and their conclusion may be 

 said to be confirmed by the Oregon specimen. Nevertheless, this 

 would not probably have more than doubled the length of the grind- 

 ing surface of the upper premolars, making it about 46 mm., just 

 enough to cover the hindermost lower premolar. So far as appears 

 there was nothing to oppose the anterior lower premolar. Another 

 rather remarkable thing is that the hindermost upper premolar was 

 so smaU in comparison with the last lower one. 



It occurred to me that possibly the tooth in the Japanese specimen 

 which is regarded as the last lower premolar was really the first molar. 

 The lengths of the grinding faces of the two teeth are not greatly dif- 

 ferent; and on that supposition the anterior premolar would be op- 

 posed by the two upper premolars. This view would involve the 

 removal of the lower jaw backward a distance of 47 mm. The Japa- 

 nese authors had already concluded that the tip of the upper jaw 

 protruded beyond the lower about 40 mm. The two sums together 

 would amount to 87 mm. As the distance from the front of the 

 upper jaw to the front of the nasal opening is given as 70 mm., we 

 would have the tip of the lower jaw about 17 mm. behind this opening. 

 This does not seem probable. Moreover, the crown of the upper first 

 molar has a height of 60 mm., while that of the lower tooth which we 

 are assuming to work against it has the crown worn down to a height 

 of 25 mm. This is not likely to have been true. I am at present 

 unable to solve the problem presented. 



The tooth regarded, and probably properly so, by Yoshiwara and 

 Iwasaki as the first lower molar had a crown whose length is given as 

 64 mm., width as 40 mm., and height as 39 mm. It consists of three 

 transverse rows each with two columns. It has the dimensions of 

 the first upper molar and was therefore a worthy antagonist of it. 



From Yoshiwara and Iwasaki's paper we learn that in tlieir speci- 

 men the first upper molar had three columns in the front transverse 

 row, while the corresponding lower molar had only two columns in 

 each row. On the other hand, the last lower premolar had three col- 

 umns in the hinder row, two each of the other two rows. 



Thi'ough the kind offices of Mi-s. McCornack, I have received for 

 examination from Prof. Warren D. Smith, head of the geological 



