INTRODUCTORY OBSERVATIONS. 
XV. 
five specimens agree so exactly with, one another that there can be little or no 
hesitation in referring them to one and the same species. Their essential characters 
are that the ridges are moderately tall, and inclined forwards ; the valleys partially 
Fig. 5. Mastodon cautleyi. The first left upper true molar in an unworn condition ; from Perim 
Island, x- British Museum (No. M. 2817). The lower border of the figure is the inner border of 
the specimen. 
blocked by accessory tubercles, of which there are none on the outer side of the 
median longitudinal cleft. Tlie first inner column always has accessory tubercles on 
both sides, and there are similar tubercles on the hinder side of both the second and 
third inner columns ; the hind talon of the ‘ intermediate ’ molars (woodcut fig. 5) 
is relatively small ; while in unworn examples the hinder aspect of the outer column 
of the first ridge is deejdy concave, and the arrangement of the tubercles on the 
inner column of the same ridge forms a V. The third true molar (woodcut fig. 6) 
Fig. 6. Mastodon cautleyi. The third left upper true molar, in an unworn condition ; from the Siwaliks of 
Perim Island. British Museum (No. M. 2705). The lower border of the figure is the inner border of the 
specimen. 
is very wide, tapers but little posteriorly, and carries five ridges and a simple hind 
talon, the latter consisting of a narrow ridge with six small tubercles. All the teeth 
are relatively wide, with a well-marked median longitudinal cleft ; they appear to 
