167 



Between the molars, the interval is about that of the antero- 

 posterior width of a member of the series, and is about the 

 same as exists between the front molar and last premolar. The 

 hindermost molar, smaller and simpler than the others, is also 

 compressed antero-posteriorly ; still, it shows rudiments of the 

 details just described, the suppression of parts being most marked 

 in the beak-shaped internal cusp, which is here only feebly repre- 

 sented by a ridge with a narrow worn surface. 



Ma7idihle. — There are two peg-like incisors of nearly equal 

 size sloping forwards and showing a " mark." The apex of the 

 next tooth, when the jaw^s are closed, passes just in front of the 

 upper canine, and belongs presumably, therefore, to the same 

 category (Hg. 11, c). Behind this come three teeth, which T take 

 to be premolars. (PL VI., figs. 1 and 11). The most anterior, 

 which is not shown in the figures being absent in the specimen 

 from which they were draw^n, is about the size of the canine, 

 but has its front border elevated into a rudimentary cusp, and 

 a wearing surface sloping inwards. Then follows a minute 

 styliform tooth, scarcely as thick as the shaft of an ordinary 

 sewing needle, and about half the length of that just described. 

 This is represented in fig. 1 1 immediately succeeding the canine (c). 

 The hindermost premolar is a more developed type of the first, 

 and much larger. Its anterior border is raised into a pointed 

 cusp, from which a wearing surface slopes backwards and inwards, 

 and bears it at its hinder extremity a small posterior cusp. A 

 small wearing surface, also, shows on the outer face of the tooth. 



The four true molars which follow resemble one another, but 

 diminish in size from before backwards ; a horizontal section is 

 approximately triangular, with the base inwards (figs. 7 — 10). The 

 external border, corresponding to theapex, rises intoa sharp pyrami- 

 dal cusp (a)^ and so also do the borders corresponding to the angles 

 at the base (h, c), only they are less elevated and more rounded. 

 Between these three cusps is a concave worn surface. An interval 

 equal to half the width of a tooth of the series separates the teeth 

 of this order ; but from the obliquity with which the teeth are 

 set in the alveoli these spaces are not seen when the jaw is 

 viewed at right angles to its long axis, the outer and hinder 

 border of one tooth overlapping the space intervening between 

 this and the one behind. 



The hindermost tooth of all is the fourth maxillary molar, the 

 external cusp of the last mandibular molar passing between the 

 fourth and tlie third of the maxillary series, the penultimate 

 mandibular molar between the third and second, and so on The 

 external cusps of the lower molars play up and down in the inter- 

 vals between the large pointed cusps of the upper series, and the 

 concave triangular surface between the three cusps of the lower 



