164 DE. C. W. ANDREWS OX LOWER MIOCENE [June I9I4 r 



group attained a high degree of differentiation before it declined 

 to its present obscure position. The Rodent is perhaps a direct 

 descendant of Phiomys of the Egyptian Upper Eocene. Of the 

 Reptilia the most important is the giant species of Testudo, which 

 is especially interesting as giving further proof of the wide dis- 

 tribution of these creatures on continental areas in Tertiary times. 

 The fact that these reptiles in recent times are found only on 

 islands may be simply explained by supposing that they are survivals 

 of formerly more widespread groups, and have escaped extinction 

 owing to a relative absence of enemies and of competition under 

 insular conditions. 



It is unfortunate that in the collection now described most of 

 the species are represented by mere fragments ; nevertheless, they 

 are sufficient to show that future investigations among the Tertiary 

 deposits of this region will yield most valuable results. 



PKOBOSCIDEA. 



The most important specimen referable to a member of this- 

 group is an imperfect right ramus of the mandible of D in ci- 

 ther ium liobleyi Andrews, the symphysial and posterior portions 

 of which have been broken away; the cheek-teeth (pm 4 -m 3 ) are 

 beautifully preserved. This mandible is rather smaller than that 

 upon which the species is founded, 1 and is more complete ; in the 

 type-specimen m x was wanting. 



Anteriorly the jaw is broken across immediately in front of the 

 point where it begins to curve inwards and downwards towards the 

 deflected symphysis characteristic of the genus, the deflection 

 commencing at about the level of the posterior ridge of pm 4 . 

 Behind this, as far as the posterior end of m„ the inner face of 

 the jaw is nearly flat. Behind this, again, the upper half of the 

 inner face curves gently outwards towards the posterior expansion, 

 while the lower half is concave from above downwards. The 

 ventral border of the ramus is nearly straight until some 4 or 5 

 centimetres behind the dental series, where it is interrupted by a 

 roughened tuberosity, projecting a little outwards and downwards, 

 and separated from the angular region by a well-marked notch ; 

 the greater part of the angular region is wanting. 



The outer face of the ramus beneath pm 4 and m l is slightly con- 

 cave from above downwards, but below and behind this it becomes 

 strongly convex in that direction, passing below by a wide curve 

 into the inner face. The mental foramen is situated rather more 

 than half way down the outer face of the jaw beneath pm 4 . The 

 anterior edge of the ascending ramus is situated about opposite the 

 second ridge of m 8 , and it arises some distance below the alveolar 

 border, from which it is separated by a broad concave surface. A 

 strong ridge, continuous at its lower end with the inner edge of the 

 alveolar surface, runs upwards and forwards on to the inner face of 



1 Proc. Zool. Soc. 1911, p. 943. 



