APPENDIX. 213 



three-ridged molar, also deciduous. On the left side of the same jaw, as appears by the figure, 

 an opening has been made at the roots of the second and third teeth, to ascertain the existence 

 of a vertical premolar ; but none such was discovered. 



The lower figure gives a front view of the same jaw, and exhibits the sockets of the two 

 inferior or tetracaulodon tusks. 



PLATE m. 



In this are displayed the teeth in a continuation of the series. The first tooth in front is 

 the tooth corresponding with the last in the preceding plate. The second tooth immediately 

 follows the preceding, and is the fourth in the complete series, the second three-ridged molar, 

 and first permanent. Behind it lies the partially developed fifth molar. At the anterior part is 

 a good view of the lingual fossa, and truncated extremity of the jaw. 



PLATE IV. 



This is the upper jaw of a perfect cranium, to which belonged the lower jaw represented in 

 Plate III. The reference to the teeth in the last plate applies to this also. The tooth in front 

 is the first three-ridged molar, — the third tooth of the entire series. The next in order is the 

 second of the three-ridged molars, the first permanent or fourth of the entire series; while 

 the third three-ridged, or fifth in order of succession, is but partially developed. 



We see also the palatine vault, narrow behind, and widening as it extends forwards to the 

 anterior teeth, in front of which it again narrows. Behind the palatine vault are seen the pos- 

 terior openings of the nostrils, and the pterygoid processes. Laterally are the zygomatic arches. 

 Quite at the back part, or lower edge of the plate, are the great occipital foramen and the 

 condyloid processes, more fully displayed than in the other plates. 



PLATE V. 



This jaw presents a greater number of teeth than any other. On the right side exist four ; 

 the two first have been seen in the former plates ; the third on this side is the fifth in the 

 dental series, the third three-ridged, the penultimate molar. Behind it lies the partially deve- 

 loped ultimate or sixth molar. 



The three anterior teeth on the left side have been shed. In front is seen the lingual 

 groove, and behind are the coronoid and condyloid processes of the lower jaw. 



