1857.] FALCONER MASTODON. 319 



arrangement in Natural History is, that the technical characters, how- 

 ever abridged, should be exponents, so to speak, of the natural and 

 serial affinities, and in nowise at variance with them. If this test 

 be applied to the ridge-formula, as a consistent basis for the arrange- 

 ment of the Mastodons and Elephants, it will, we believe, not be found 

 wanting : thus the Mastodons ranged under Trilophodon and Tetralo- 

 phodon include all the Elephantoid species which have the crowns of 

 the molars comparatively simple, and uniformly divided into two 

 subequal divisions by a longitudinal line or cleft ; the ridges limited 

 in number, each with fewer mammillary eminences, and invariably 

 more or less concave across ; the enamel thick and in conical or com- 

 pressed points ; and the valleys between the ridges deep and empty, or 

 with but a sparing quantity of cement. The Elephants, on the other 

 hand, as restricted by the ridge-formula and ranged under Stegodoriy 

 Loxodon, and Euelephas, include all the Proboscidean species which 

 have the crowns of the molars more complex, and usually wanting in 

 a longitudinal line of division ; the ridges more numerous and less defi- 

 nite, each being composed of a greater number of mammillary or digital 

 points, which are most elevated in the middle, rendering the ridges 

 convex across, instead of concave ; the processes of enamel thinner, 

 higher, and more divided ; and the deep narrow valleys between them 

 entirely filled up with cement. The limitations of the two genera 

 agree pretty well with the views generally entertained by palaeontolo- 

 gists regarding them ; with the exception, that the group comprising 

 the collective Mastodon Elephantoides of Clift, and by some called 

 transitional Mastodon^, is here regarded as more properly belonging 

 to the Elephants. 



A Synoptical Table is appended of the species of Mastodon and 

 MephaSyTSLQ^ed under subgenera, after the manner here indicated. The 

 species were first determined or adopted after a careful examination 

 of all the original materials accessible, in the foreign collections already 

 referred to (p. 309) or in various museums in the United Kingdom, 

 They were then arranged serially, according to their relative affinities, 

 as indicated by the molar teeth ; the common characters were next 

 analysed, to furnish a key for breaking up the mass of species into 

 groups representing genera and subgenera ; and the synoptical table 

 shows the result. It is put forward as exhibiting a fair represent- 

 ation of the subject so far as the materials and state of knowledge 

 at the present time admit, but with no pretension to being either 

 unexceptionable or complete. The progress of investigation, by the 

 discovery either of new forms, or of more abundant materials of the 

 species which are now the most imperfectly determined, will in all 

 probability modify more or less, or break down, any generic or sub- 

 generic limitations that may be at present devised. For the daily 

 experience of every department of Mammalian palaeontology tends 

 to show, that, while the characters of species are persistent over wide 

 areas and through long periods of time, genera are nothing more 

 than ideal or conventional centres, around which groups of species 

 are arranged, subject to incessant modifications through the discovery 

 * Owen, * Odontography,' p. 624. 



