116 PKOF. W. BOYD DAWKINS ON A PLIOCENE [May I903, 



(c) Mastodon arvernensis, Croizet & Jobert. 



It was the discovery of teeth of Mastodon that drew attention to 

 the existence of the ossiferous cave at Doveholes. This mammal is 

 represented by eighteen teeth, exclusive of fragments, and many 

 broken and waterworn bones. These remains belong to the 

 Mastodon arvernensis of Croizet & Jobert, defined by Falconer, and 

 brought before the Geological Society in 1857. 1 



In that masterly paper Falconer, after the examination of most 

 of the remains of Mastodon found on the Continent, assigned the 

 molar teeth of this species to the tetralophodont, or four-ridged 

 group, and proposed for it the following dental formula : — 



1 3 



Deciduous dentition : I -, Dm „. 



1 2 3 



Permanent dentition : I Pm ~ v M ^. 



He gave no description of the deciduous incisors or milk-tusks, 

 and left the question open as to their presence in the lower jaw. 



The four milk-tusks that I have examined present perfect tips, 

 covered with strougly-wrinkled enamel, in various stages of wear. 

 They are oval in section, and are remarkable for their small size. 

 The smallest (PL IX, fig. 2) is 57 millimetres long, and 13 broad, 

 and has a basal circumference of 40 mm. It consists of a grooved 

 basal portion of dentine, with an obtusely-pointed spatnlate tip of 

 thick wrinkled enamel, convex on the outer side, and slightly tumid 

 on the inner. The enamelled tip is 28 millimetres long, and 

 13 broad. This is a right lower milk-tooth of the deciduous series, 

 and establishes the fact that the species possessed a pair of milk- 

 tusks in the lower jaw. 



The fragment of a larger specimen (PI. VIII, fig. 5), 94 millimetres 

 long, and 05 in circumference where the enamel ends, has an obtusely 

 pointed tip, with the enamel nearly worn off by use. It is rounded 

 on the outside, and flattened on the inside. A third (PI. IX, fig. 3) 

 has a remarkably thick and longitudinally grooved capping of 

 enamel, which gradually diminishes in thickness as it passes down 

 over the dentine. The length of the fragment is 94 millimetres, 

 and the circumference at the broken margin of the enamel measures 

 70 millimetres. The strong grooves in the enamel are represented 

 by shallower longitudinal grooves in the dentine, exposed by the 

 removal of the enamel-covering. The unworn apex of the tusk is 

 mammillated. The inner side is flattened oval, the outer strongly 

 convex, a character presented by the preceding as well as the 

 succeeding specimen. These characters are repeated in the fourth 

 and largest of the series, which measures 120 millimetres in 

 length, and 90 in basal circumference (see PI. IX, fig. 4). 



The three larger teeth are fragments of the milk-tusks of the upper 



1 Quart. Journ. Geol. Soc. vol. xiii, p. 307 & vol. xxi (1865) p. 253 ; see also 

 Cb. Murckison, 'Palasont. Mems. of Hugh Falconer' vol. ii (1868) pp. 1-64. 



