96 BRITISH FOSSIL ELEPHANTS. 



never transposed or reversed,"^ does not invariably hold good by any means. To suppose 

 that the specimen, p. 90, is also a last milk molar vv^ould make the owner a dwarf. 



Of fourteen entire last upper milk molars, nearly all of which were from British strata, 

 I found one with a ridge formula of x 9 x, two holding x \^ x, six with x 11 x, and 

 six with X \2 X. It would seem, therefore, that the plates vary from 11 to 12 in upper- 

 jaw molars. 



Loioer molars. — Mandibular last milk molars are equally plentiful, and they are 

 oftener seen in situ than the opposing tooth. Great variation in size obtains as usual in 

 jaws of the same age, at all events containing teeth similarly worn, and is, no doubt, a 

 consequence of sex, individual peculiarities, and, as before stated, perhaps local varieties. 



Several molars showing various stages in the detrition of this member of the milk 

 dentition from Walton-on-the-Naze, Essex, are contained in the Woodwardian Collec- 

 tion. Among them is a left ramus of a mandible (No. 26), with the third milk tooth 

 in full wear and the fourth appearing above the alveolus, the heel of the former being in 

 a line with the anterior border of the coronoid. The tooth holds ^ 10 cT in 4 X If inches. 

 The height of the jaw in front of the milk molar is 4*5 inches, and maximum thickness of 

 the ramus is 3*6 inches. There is no internal foramen in the spout, which is an 

 abnormality in the Mammoth. This ordinarily would be considered a small last milk 

 molar, and is out of proportion to ultimate true molars from the same locality, to be 

 described in the sequel. 



A mandible in the Museum of Practical Geology, Jermyn Street, from the brick-earths 

 of Otterham, shows the crowns of two last milk molars with a morsel of the penultimate 

 milk tooth in front of them, and the loose collines of the first true molar in their capsules 

 behind.^ The stage of growth is that, when the penultimate milk tooth is on the point 

 of disappearing and the last is just coming into use, there being only six of its disks 

 invaded : there is a loss of the condyles and the coronoid, and the left ramus is broken 

 across through the middle of its diasteme. Each milk molar holds x \^ x in 

 4^X 1|- inches, the enamel of which is thin. The height in front of the fragment of the 

 second tooth is 4*2 inches, and the maximum thickness of the jaw at the base of the 

 coronoid is 3J inches. 



The diasteme is nearly vertical, with a large nutrient foramen at the anterior root of 

 the second milk molar, besides two smaller openings within half an inch of the free 

 marghi, and one within the spout. 



Another portion of a lower jaw in the same Museum, and from Crayford, in the 

 Thames Valley east of London, presents precisely the same dental conditions as the last, 

 only the ultimate milk molars hold x 11 x in 44 X \\ inches, the height in front of the 

 penultimate milk is 4| inches, and the thickness at the base of the coronoid is 3 inches, 

 and there are two external and one internal mental foramina on either side. 



' Op. cit., vol. ii, p. 10. 



2 The mandible, fig. 8G of the ' British Fossil MammaLs seems to represent this stage of growth. 



