82 BRITISH AND EUROPEAN FOSSIL ELEPHANTS. 



of the ' intermediate molars ' are never less than six ; and in 

 the species, fossil and recent, that are furthest removed from 

 Mastodon in affinity, they range as high as 16 or 18 in the 

 penultimate true molar, or third of the ' intermediate' series. 

 They are not isomerons, as in the Mastodons, but deviate 

 from the numerical symmetry either by an augmentation of 

 one ridge to the crown of the last ' intermediate molar,' 

 constituting the hypisomerous forms, or they are more nume- 

 rous, and augment by progressive increments corresponding 

 with the increase of age, including the cmisomerous forms. 



The Elephants with hypisomerous-ridged molars are divi- 

 sible into the two natural groups, Stegodon and Loxodon ; the 

 cmisomerous species form a third natural group, for which, as 

 already explained, the term Enelephas is proposed. 



III. — Characters of the Stegodons. 



1. General Remarks. — The Stegodons form the nearest 

 approach in natural affinity to the Mastodons, and more 

 especially to that subdivision of the section Tetralophodon 

 which comprises M. (Tetraloph.) longirostris and M. (Te- 

 traloph.) latidens. This is evinced by the low elevation and 

 transverse direction of the crown-ridges, by their nearly 

 uniform height throughout the length of the crown, by their 

 thick enamel, and by the mammillary form of the ridge- 

 processes. A fragment of one of these teeth, denuded of its 

 coat of cement, and seen by a naturalist for the first time, 

 would at once be referred to Mastodon rather than to Elephas ; 

 and it was this broad resemblance which struck Clift so for- 

 cibly that he applied to them the designation, at the time 

 very appropriate, of Mastodon Elephanto'ides. But when the 

 essential characters are analyzed, the species are seen to 

 partake more of the nature of true Elephants : — 



1st. In the greater number of the crown-ridges and of the 

 mammillae or points that enter into the composition of each. 

 2nd. In the agreement of the ' ridge-formula' of certain of 

 the species with that of the existing African Elephant and 

 other Loxodons. 3rd. In the convex outline of each ridge 

 in the transverse direction when unworn, the central mam- 

 millee being the most elevated ; and in the absence of the 

 longitudinal line of division along the middle of the crown 

 which is so characteristic of the Mastodons on the one hand, 

 and so generally absent in the Elephants on the other. 4th. 

 In the enormous quantity of laminated cement that fills 

 up the valleys in most of the species. 5th. In the pro- 

 nounced arc of a circle described by the molars as we trace 

 them forwards in the jaws, as in the Elephants, instead of 



