SYNONYMS. 



237 



The formula in the North American Mammoth is identical 

 with that of the Siberian and European forms. Exceptions 

 are occasionally met in which an unusual number of plates is 

 presented. For instance, Dr. Warren figures and describes a 

 last upper molar from Ohio, in which, including talons, the 

 tooth presents thirty -two ridges. 1 But Mastodon Ohioticus, 

 in which the dental characters are very constant, occasionally 

 exhibits a similar numerical excess in the ridges in the last 

 true molar. 2 



There is one peculiarity, however, in the molars of the 

 North American Mammoth which is so constant, that, I 

 believe in most instances, by means of it, they can be dis- 

 criminated in a mixed collection of European, Asiatic, and 

 American specimens, namely, that the ridges and their con- 

 stituent elements are more attenuated and condensed. Tor 

 example, in the Museum of the College of Surgeons there is 

 a palate-specimen (No. 620 of Cat.) containing the ante- 

 penultimate true molar, on either side perfect but well worn. 

 On the left side the tooth measures 5 inches long by 2*7 in. 

 wide, and presents the discs of 14 ridges, inclusive of the 

 two talons, being an average of but - 36 inches to each. A 

 superb specimen of a last upper, in the Hunterian collection 

 from Ohio, presented by Dr. Casper Winter (No. 615 Cat.), 

 exhibits 17 discs of wear in a length of 7*7 inches, giving an 

 average of '46 to each ridge ; while a last upper molar from 

 Siberia, presented by Dr. Eogerson, gives an average of *54 

 for each ridge. Taken singly, the difference seems incon- 

 siderable, but when uniformly repeated over a length of crown 

 comprising sixteen or twenty-four ridges, it is perceptible a/t 

 a glance, and gives a certain amount of distinctive phy- 

 siognomy to the molars of the North American Mammoth. 

 The same character is seen in specimens from Eschscholtz 

 Bay, e.g. in a palate (No. 24,585) Palseont. Gallery, British 

 Museum. But I do not regard it as indicating more than a 

 slight geographical variety, for the other characters, such as 

 the form of the lower jaw, &c, remain constant to the true 

 Mammoth type. 



It has been asserted that the kind of molar upon which 

 E. meridionalis is founded occurs not only in England, but 

 as far north as Eschscholtz Bay in Arctic America ; and the 

 figures given by Buckland, in the voyage of the ' Blossom,' 



below, characteristic of the antepenulti- 

 mate and penultimate true molars, the 

 discrimination of -which always presents 

 the greatest difficulties. 



1 On ' Mastodon giganteus,' p. 1 63, 

 PI. xxviii. fig. c. 



2 On ' Mastodon giganteus,' p. 79. 



the series should have been : 

 Milk molars. True molars. 



4, 8, 12, 12, 16, 24, 



4, 8, 12, 12, 16, 24-27. 

 The correction, it will be observed, 

 applies solely to the ciphers above and 



