E. (loxodon) PLANIFRONS. <tl 



nounced a degree in the African Elephant might have led us 

 a priori to expect in nature other allied species in which it 

 would be more or less exhibited. Premolars have not as yet 

 been observed among the teeth of this species. 



3. E. (Loxodon) planifrons. — In order to show the constancy 

 of the hypisomerous character of the ridge-formula among 

 the Loxodons, as furnishing a reliable aid in the distinction 

 of certain of the European fossil Elephants, it is necessary to 

 refer briefly to the dentition of another form in the sub- 

 genus, being the Indian extinct species from the Sewalik 

 hills, E. (Lox.) planifrons, the characters of which, yielded 

 both by the skull and teeth, are so pronounced, and the 

 accessible materials in European collections so abundant, as 

 to place its specific distinctness wholly beyond question. In 

 this form the ridge-formula of the deciduous and true molars 

 is thus : — 



Milk molars. True molars. 



3 + 6 + 7 7+ 8 + 10. 



3 + 6 + 7- 7 + (8-9) + (10-ll). 



Vertical sections of an upper and lower true molar con- 

 trasted with corresponding teeth of the African Elephant are 

 shown by figs. 5 a and 5 b of PL II. of the ' Fauna Antiqua 

 Sivalensis.' (See also vol. i. PL IV. fig. 2.) The ridges 

 are seen to be much more elongated vertically than those of 

 E. {Steg.) insignis (vol. i. PL IV. fig. 1), but to be considerably 

 less so than in the African Elephant (vol. i. PL IV. fig. 3) . 

 Other distinctive characters from the latter species consist in 

 the enormous quantity of cement which fills up the valleys 

 and envelopes the ridges, and in the much greater thickness 

 of the folded plates of enamel. When the teeth are regarded 

 from the crown aspect, the discs of wear assimilate more in 

 general form to those of the existing Indian than of the 

 African Elephant. They form transverse bands, which are 

 broader, fewer in number, and wider apart than in the Indian 

 Elephant, sometimes with the bounding edges of enamel 

 nearly parallel, in other cases showing a slight angular 

 expansion, or throwing out a salient loop (outlying tubercle) 

 near the middle, as in figs. 8 and 9 of PL XIV. (F.A.S.),but 

 never exhibiting the systematic lozenge-shaped expansion so 

 characteristic of the African Elephant. (See PL VI. fig. 1.) 

 The enamel edge or machceris is very thick, and generally 

 free from plaiting. The tips of the digital processes are 

 thick, and yield well-marked circular discs before they 

 become confluent by wear. These characters are represented, 

 throughout by the figures of Plates XL and XII. of the 

 ' Fauna Antiqua Sivalensis,' which include the principal 

 varieties in the form of the molar-crowns. (See also PL VI. 

 fig. 2.) 



