47 



The third premolar also is like that of Palceosyops paludosus, excepting that 

 it exhibits a tendency to the production of a basal ridge not evident in 

 the former. 



The second premolar, not present in the jaw-specimen of Palceosyops 

 paludosus, is a reduced form of the tooth behind it. A portion of the canine 

 alveolus retained in the specimen indicates a tooth of moderate size in com- 

 parison with the size of the jaw itself. 



Another 'series of lower molar teeth, attached to small jaw-fragments, and 

 represented in Fig. 2, Plate XXII I, also appear to me to be referable to 

 Palceosyops major notwithstanding certain differences presented by the pre- 

 molars. The teeth are considerably more worn than in the preceding speci- 

 men; most of the summits of the constituent lobes of the crown of the mo- 

 lars and last premolar being so worn as to exhibit islets of exposed dentine. 

 The second molar is most worn, and presents on the summits of the outer or 

 principal lobes broad, depressed, shield-shaped tracts of dentine. 



The molars have the same constitution as in the preceding specimen. The 

 last one is smaller, but the others are nearly of the same size, except that the 

 first one is thicker, especially at its fore part, and is therefore of more uniform 

 diameter. The basal ridge of the anterior two molars is better developed 

 externally than in the former specimen. In the first molar the anterior lobe, 

 being proportionately rather better developed than in the corresponding tooth 

 of the previous specimen, its anterior ridge curving inwardly, is stronger, and 

 it embraces a more conspicuous fossa. 



The last premolar differs somewhat in proportions from that of the former 

 specimen, but is otherwise nearly the same, except so far as it is altered in 

 appearance from being more worn. It is of less breadth fore and aft, and 

 is thicker, and it does not present the ridge at the fore part of the base, 

 externally, of the anterior lobe, being in this respect more like the corre- 

 sponding tooth in the jaw-specimen of Palceosyops paludosus. 



The third premolar differs from that of the former specimen very much in 

 the same maimer as the succeeding tooth. The crown is of less breadth fore 

 and aft, and is thicker. It has exactly the same constitution, but looks differ- 

 ent on account of its more worn condition, its difference of proportion, and 

 from the absence of a basal ridge occupying the fore part of the crown, exter- 

 nally, in the former specimen. 



Comparative measurements of the teeth and jaws of the specimens just 



