ELEPHAS PRIMIGENIUS.— TRUE MOLARS. 



101 



The plates are ratlier tldch, but mostly with reference to the cement and dentine ; 

 indeed, all Lexden specimens I have seen vary considerably in the thickness of their 

 plates. ^ 



Foreign specimens. — The Museum of the Royal College of Surgeons of England con- 

 tains several admirable illustrations of lower as well as upper first true molars, said to 

 have been obtained from Oiiio, N. America. They are described with Dr. Ealconer's 

 usual fidelity, and need no further reference here, excepting as regards their ridge 

 formulae, which do not exceed x 12 x, and the very attenuated enamel pointed out by Owen 

 and Falconer.^ I have already referred to these teeth in connection with the American 

 distribution of the species. 



An upper molar. No. 37,293, B. M., from " gravel pits " near Moscow, holds a' 1 2 <?; in 

 5f X2"7 inches with 8 ridges in a space of 3^ inches. The enamel is crimped somev.liat 

 near the middle of the disk and is thick. 



Several suggestive specimens of this tooth are contained in mandibles. 



A lower jaw figured and described by Falconer^ displays the first true molar fully 

 worn, and the empty socket of a fragment of the last milk in front with the tips of the 

 collines of the penultimate true molar just appearing. 



In the Brady Collection a further stage in the detrition of the molar in question is well 

 represented in the mandibles, Nos. 43 c and 44 c. The former is shown (Plate VIII, 

 fig. 2). A crown very slightly more worn, with the second true molar just above the gum 

 and one of its ridges attrited, is represented by No. 47 and No. 45 of the same collection, 

 where several of the anterior plates of the fiist molar are worn away and two of the 

 anterior of the second in use, whilst No. 4G shows only half of the ante-penultimate 

 remaining and five plates of the penultimate invaded. 



All these mandibles present considerable discrepancies in size, irrespective of the 

 state of wear of the first true molar and its predecessor and successor as they happen to 

 be in use or not, and no doubt refer to sexual and perhaps also individual peculiarities ; 

 thus the maximum length, thickness, and divergence of the rami, in the order of advance- 

 ment of detrition of the crown just given, arc as follows : 



F. A. S., pi. xiii, fig. 2.— B.M 



No. 43, Brady Collection 



No. 44 ditto 



No. 45 ditto 



No. 4fi ditto 



No. 47 ditto 



Length of 



mandible. 



lG-8 



nches 



19 



3> 



21 



,, 



23 



J» 



22 



>> 



20 



>> 



Thickness of 

 ramus. 



4-8 inch 



4-3 



5 



5-5 

 5 



4-8 



Maximum diverg- 

 ence of ramus. 



16 inches, 

 16-5 „ 

 20-.5 „ 



22 „ 



19 „ 

 21-5 „ 



1 Refer to pp. 80 and 110. 



2 'Brit. Foss. Mammals,' p. 2;58 ; ' Pal. Mem.,' ii, 237, and pp. 164 and 171. 



3 'Fauna Antiqua Sival.," pi. 13 a and B, and figs. 2 and 2a, 'Pal. Mem.,' vol. i, p. 439. This 

 specimen from Germany is preserved in the British Museum. 



14 



