THE MALTESE POSSIL ELEPHANTS, 7 



common than the first ; and the inward dimensions are partly due to a thicker enamel, 

 but more so to the thicker dentine of the plates. 



" This conclusion as to the varieties is not derived from the worn surfaces of the teeth, 

 but from the space a given number of plates occupy in any portion of an antero-posterior 

 line midway between the grinding-surface and the base of the molar. 



"As an illustration I send you the measurements of the spaces which eight plates 

 occupy in six upper ultimate molars of corresponding size, and of small individuals. 



ijicheg. 



1. From Eschscholtz Bay 2-8"| 



2. From Ballingdon, Herts 2-9 > Thin-plated. 



3. From cavern near Wells . • 2'9J 



4. Ilford 3-6 j 



5. Brighton 8-7 > Thick-plated. 



6. Erith 4-oJ 



" In a very large tooth of this species, dredged off Happisburgh, the same number of 

 plates fill a space of 4-7. 



" But the teeth of fossil Elephants are so variable in size and character, that it is 

 impossible to di-aw a line by measurements between the thin-plated and the thick-plated 

 varieties ; I distinguish them more by general appearance and character of the teeth, 

 than by the assistance of compass and rule. All the thin-plated molars are shorter, and 

 the setting of the plates much more compact. I believe, from my personal experience, 

 that the varieties are local ; but I cannot positively assert it." 



What has been designated the " talon-complication " is, as regards the molars of the 

 Maltese fossil Elephants, quite as embarrassing as in other species. The varieties of 

 form and shape assumed by the first and last ridges prove, at all events, the necessity of 

 invariably including all enamelled laminae in the ridge-formula, whether sprmging from 

 the body of a plate, or in common with it arising from the base at the reflections. 

 Sometimes, however, they are rudimentary, forming small digitated splints, or enamelled 

 eminences, or a talon-shaped ridge, so that it is difficult to decide whether or not such 

 should be included in the estimate ; and this, as regards certain molars, is of considerable 

 importance with reference to specific distinctions, as will be shown presently. Dr. 

 Falconer lays much stress on the number of ridges, combined with their characters, as 

 diagnostic of species of Mastodon and Elephant ; indeed, as regards the latter, he has 

 founded the subgenera Stegodon, Loxodon, and Euele])has entirely on dental features. It 

 must, however, I opine, be generally admitted that, invaluable as are such data when 

 taken as characteristic of types or forms, both the characters and ridge-formulas are apt 

 to vary, not only in allied species, but, as just observed, in members of the same species. 

 Indeed, to arrive at even an ordinary estimate, it is necessary to examine a much larger 

 assortment of materials than come usually within the reach of a single observer. 



