104 BRITISH FOSSIL ELEPHANTS. 



attaches itself to this tooth, as has been pointed out in connection with its predecessors in 

 the dental series. 



Until Falconer's differentiations established a rid2;e formula of ^r 16 .v for the second 

 true molar of the Mammoth, none of his contemporaries or predecessors had estimated 

 the number very definitely.^ But the average number assigned by him is subject to 

 numerous exceptions, and is apparently, as far as I have been enabled to observe, too 

 high an expression. Falconer states, " I have seen no authentic specimen of an 

 upper penultimate of the Mammoth presenting more than sixteen or seventeen ridges. 

 That exceptional cases do occur in which as many as eighteen may be seen is not 

 improbable, but, I believe, that as holds in the existing Indian species the prevaihng and 

 normal number is sixteen."" He also refers to the tooth described by De Blainville,^ in 

 which fourteen collines exist, and doubts if the molar belongs to the Mammoth. That a 

 penultimate true molar of the Mammoth may contain this ridge formula is proven, it 

 appears to me, by the following instances. 



Upper molars. — In the rich collection of molars belonging to the Mammoth lately 

 obtained from the Oxford gravel, and now in the University Museum, is an upper and 

 lower penultimate true molar, each containing ct' 14 cv. The upper is 6'7x2'S inches, 

 and contains eight ridges in 3|-. The other will be referred to presently. 



Another and smaller upper tooth, holding the same cV 14 w ridge formula in 5x3 

 inches, and eight ridges in 3^, is preserved in the Museum of Practical Geology, Jermyn 

 Street. It is from the low^er brick-earths of Crayford on the Thames, and is interesting 

 also on account of the t/iin enamel of the crown, as compared with that of the llford 

 specimens, as will be referred to again presently. 



The two molars. No. 23,115, evidently of the same individual, from Maidstone, 

 Kent, in the National Collection, show the ridge formula o^ x 14 x in 7x2^, and eight 

 ridges are contained in 39 inches. That these teeth are penultimate true molars is at once 

 apparent from their size and the characteristic declination of the posterior ridges, and 

 the flat pressure mark on the last ridge and fang. The disks present the usual parallel, 

 narrow, and uncrimped characters of the Mammoth. The enamel is i/iic/c, and the plates 

 much digitated, as often prevails. It is noteworthy that several of the posterior plates 

 present roughenings and irregularities, as if several additional ridges had been suppressed 

 during development, and might, if unsupported by further data, be considered deformed 

 teeth, but the other instances and examples in lower teeth, to be referred to immediately, 

 appear to me sufficient to establish the not uncommon ridge formula of x 14 x in second 

 true molars. 



1 Owen states it " may Lave from sixteen to twenty-foui- plates." De Blainville mentions molars 

 with fourteen, eighteen, and nineteen plates or collines. ' Brit. Foss. Mam.,' ' Odontography,' p. 6G6, and 

 ' Osleographie des Elephants,' pp. 195, 357. 



- Op. cit., vol. ii, p. 168. 



■' 'Osteog. des Elepliants,' p. 195. 



