150 



FAUNA ANTIQUA SIVALENSIS. 



of the jaw and alveoli has disappeared, and given place to an 

 argillaceo-calcareous incrustation of a pale yellow colour, 

 which also fills the discs of detrition of the grmding surface. 



The teeth had belonged to an adiilt animal ; the posterior 

 molar having come into use, and the anterior one being con- 

 siderably worn down. They are known to be the two last 

 molars, from the posterior one having the accessory spur or 

 process which characterizes this tooth. Their form and state 

 of detrition show that they were not the last and penultimate 

 m^ilk molars. 



They have the figure of a rectangular or nearly square 

 shaft, rounded at the corners, surmounted by a crown 

 divided into four large conical or mastoid processes brought 

 together in transverse pahs. The body of the tooth on 

 either side is contracted m the middle by a perpendicular 

 fossa down to the root, dividing it into two portions, each of 

 which has a rounded or convex surface ; so that altogether 

 the tooth has the appearance of four cylinders in apposition 

 by pairs, terminating in a crown of as many conical processes. 



IG. O. 



THE DADOOPOOE TOOTH, FROM A SKETCH BY A NATIVE ARTIST ; OF THE 



NATUEAX SIZE. 



There is no bulge or ridge of enamel making the circuit of 

 the shaft, so as to form a neck or collet ; but the crown is 

 comphcated by small transverse ridges of enamel, one at each 

 end of the tooth, and a third in the angle of junction of 

 the pairs ; these are chiefly developed along the outer col- 

 liculi, and are more or less complete forwards. 



The plane of detrition is oblique, the teeth sloping at a 

 considerable angle from their outer margin inwards ; so 

 that the coUiculi of the inner lines are truncated, while the 

 outer remain more or less conical. 



