NO. 1699. OX EDESTUS AND RELATED GENERA— HAY. 49 



conclude, therefore, either that it belonged to a much smaller species, 

 than E. minor or that it belonged among the teeth of a half-grown 

 animal. 



If now, from Eastman's beautiful figures, apparently the best yet 

 jDublished, one compares the basal length of each tooth with its height, 

 it is found tlir.t the ratio of the base to the height is 0.83, 0.82, and 

 0.81 in the first, second, and fourth teeth, respectively, 0.91 in the 

 third and sixth, 0.93 in the fifth, and 0.9T in the seventh. "W^iile 

 there are some irregularities here, no encouragement is given to con- 

 cluding that the ratio would rise in the earlier-formed teeth. Now, 

 the ratio of the base to the height in the tooth described by Karpinsky 

 IS 1.18, This means that in E. minor the base is considerably shorter 

 than the height, while in the Russian tooth the base is considerably 

 greater than the height. 



An examination of the figures of E. minor shows that the hinder 

 border of each tooth meets the anterior border of the next at an acute 

 angle. Karpinsky's figure shows that the hinder free border of the 

 tooth was turned at a right angle with the hinder cutting edge, an 

 arrangement that would have made the angle between successive 

 teeth quite ditferent from that in E. minor. A somewhat similar 

 process is seen at the hinder end of the last tooth of E. crenulatus 

 and even of E. minor., but to assume that the Russian tooth was the 

 last of the series is to abandon the supj)Osition that it was the tooth 

 of a young animal. Attention may also be called to the fact that in 

 Karpinsky's specimen the apex of the concavity of the anterior border 

 is placed between the middle and lower thirds of the border, while in 

 E. 7ninor it is placed considerably lower down; also that the hinder 

 cutting edge of E. minusculus is far more strongly convex than that 

 of E. minor. 



In the specimen studied by Karpinsky the height of the sheath, 

 taken at the front end of the tooth, is 0.3 the basal length of the 

 tooth. If the last tooth of E. minor had the same length as the one 

 immediately in front of it, the height of the sheath, obtained at the 

 hinder border of the last tooth present, would be 0.75 of the length of 

 its tooth. 



The section of the sheath of his specimen that Karpinsky has pub- 

 lished requires notice." This section shows that the lower border, 

 close to the tooth, was rounded, not sharp, as it is in E. crenulatus., 

 E. serratus., and E. heinrichii. No section of E. minor has hitherto, 

 so far as the writer knows, been published. Prof. F. S. Loomis, of 

 Amherst, Massachusetts, has kindly sent me an accurate drawing of 

 the broken hinder end of the type of the species, now deposited in the 



" Verhaudl. rnss.-kais. iiiin. Gesellsch. St. Petersb., 2(1 ser., vol. 26, 1898, p. 380, 

 fig. 16. 



Proc.N.M.vol.37— 09 1 . 



