1843.] 245 



upper jaw, corresponding exactly in size and form with that of the 

 left side, but if anything, rather more worn, and belonging therefore, 

 probably, to a different individual. The agreement extends down 

 to the small cone of enamel at the base of the hollow between the 

 barrels on the inside. Its dimensions are : — 



Length r2 inch. 



"Width 1-4 



The third specimen (PI. II. fig. 5 a. 5 b.) is a fragment of the left 

 lower jaw, containing the last molar. It has precisely the form and 

 proportions of the corresponding tooth in the left lower jaw of the 

 female head referred to, and the same development of its third 

 barrel or heel, which is always found in this tooth in ruminants. 

 Its dimensions are : — 



Length T? inch. 



Greatest width I'O 



The fourth specimen (PI. II. fig. 6.) is the last false molar of the 

 left lower jaw, detached. It agrees closely with the corresponding 

 tooth in the recent female head above referred to. This tooth is 

 thicker in proportion to its length in the giraffe than in other rumi- 

 nants, and this constitutes one of the most distinctive characters of 

 the giraffe's premolars. The anterior semibarrel appears a trifle 

 longer than the corresponding tooth of the recent animal ; but this 

 is owing to a difference of wear, and is not borne out by measure- 

 ment. The dimensions are : — 



Fossil. Recent. 



Length I'Oinch. TO inch. 



Breadth 0-9 086 



The authors are possessed of the same tooth of the right lower jaw, 

 detached ; but have not thought it necessary to figure it. 



The fifth .specimen (PI. II. fig. 7.) is the penultimate false molar 

 of the right upper jaw. It is of the same size and form with the cor- 

 responding tooth in the recent female head, with this difference, that 

 it has three tubercles at the inside of the base. On a sixth specimen 

 of the first false molar of the right upper jaw, which is not repre- 

 sented among the figures, there are three similar tubercles similarly 

 placed. It would require an extensive comparison of recent heads 

 to determine what value attaches to this peculiarity ; whether the 

 tubercles are constantly absent from the teeth of the recent species, 

 or appear occasionally as a variation on those of individuals. The 

 dimensions of the penultimate false molar of the upper jaw are : — 



Fossil. Recent. 



Length 1"0 inch. ()-9b inch. 



iJreadth 1-12 1-12 



There is a peculiar, finely reticular, striated and rugose surface to 

 the enamel of the teeth of certain quadrupeds, the appearance of 

 which the authors compare to that of a fine net, forcibly extended, 

 so as to bring the sides of the meshes together. This texture they 

 formerly described as existing on the surface of the molars of the 

 Sivatheriura. It is found also on the teeth of the recent giraffe. 



