Yol. 59.I OSSIFEROUS CAVERN" AT DOVEHOLES. 117 



jaw. The whole series has been hitherto unrecorded, and their 

 discovery at Doveholes fills a blank in our knowledge of the dentition 

 of the species. 



The permanent tusks are represented by a few fragments, broken 

 from originals of much larger diameter than the above. It is 

 obvious, from Falconer's examination of the lower jaws of Mastodon 

 in the Museums of Turin and Florence, that the adult M. arvern- 

 ensis possessed no lower tusks. 



The Molar Series. 



The molars discovered at Doveholes, 21 in number, present all the 

 characters of the tetralophodont section of the genus Mastodon. 

 Their ridge-formula is as follows : — 



Tvr-it i 2+3+4 3+4 4+4+5 . 



Milk-molars: 2^3^, Pm ^ M _-. 



Falconer only considered the milk- and the true molars, leaving out 

 of account the two premolars, which have the ridge-formula of the 

 penultimate and ultimate milk-molars that they displace. 



The specific characters of the molar series of M. arvemensis are 

 the strongly mammillated and wrinkled ridges (a) of the crown, 

 and the development of wart- like secondary cusps (6), which 

 block up the centres of the transverse valleys (c). The longitudinal 

 depression in the centres of the transverse ridges (PI. IX, fig. 5 & 

 PL X, fig. 1) is marked by a zigzag line in the crowns. The cusps 

 forming the transverse ridges (a) are arranged diagonally so as to 

 form an alternate pattern with the secondary cusps (/>), zigzagging 

 from the front to the back of the crown. In all there is a strong 

 front and back talon (d). The wrinkling and grooving of the 

 enamel is more strongly marked in the milk- than in the true molars, 

 and the upper may be distinguished from the lower series by their 

 greater width. 



The first milk-molar (dm 2) is probably represented by a stump 

 too imperfect to be figured, which resembles that figured by Croizet 

 & Jobert from Auvergne. 1 The upper penultimate milk-molar 

 dm has not so far been discovered at Doveholes. Its dimensions 

 are recorded in the table of measurements on p. 118, from the 

 cast of a specimen from the Eed Crag in the British M useum (Natural 

 History). It is a perfect tooth, with the three ridges and talon before 

 and behind. 



The last upper milk-molar is represented at Doveholes by several 

 teeth, of which two are figured in PI. X, figs. 1 & 2. They 

 have the characteristic four ridges («) and two talons (d), which 

 are united towards the central parts of the valleys of the unworn 

 tooth (PI. X, fig. 1) by flanking bosses of enamel. These, as 

 may be seen in the figure, form a zigzag pattern on the surface 



1 ' Eecherches sur le3 Ossemens Fossiles du Departement du Puy de Dome 

 Pachydermes, pi. i, fig. 2 (4to, 1828). 



