Description of Plate XXXIII. — continued. 



h. Impression of the three premolars on the matrix. 

 t. Empty sockets of the two true molars. 

 n. Orifice of dentary canal. 



o. Indication of the raised and inflected fold of the posterior 

 inner margin. 



Pig. 5. k. Third or largest premolar, showing the seven diagonal grooves ; 

 magnified 5^ diameters. 



Pig. 6. I. Corresponding premolar in the recent Australian Hypsiprymnus 

 Gaimardi, showing the seven vertical grooves; magnified 3^ 

 diameters. 



Figs. 7, 8, 9, and 10. Plagiaulax Becklesii. Portion of the right ramus 

 of a lower jaw, and different views of the two true molars. 



Fig. 7. A portion of the jaw, with two molars in situ, mag- 

 nified 10 diameters ; fig. 8, inner side of the molars, magnified 

 10 diameters ; fig. 9, outer side, 7 diameters ; fig. 10, summits 

 of the crowns of the molars, 7 diameters. 



Fig. 7. d. Anterior margin of the coronoid process. 

 b. Fractured posterior margin. 

 pm. Impression of the last premolar. 

 m. 1. First true molar. 

 in. 2. Second true molar. 



Figs. 8, 9, and 10. a. Anterior inner point of penultimate molar. 



b. Posterior inner point of the same molar, showing the disc of 

 wear. 



c. Anterior outer point. 



d. Posterior outer edge. 



ee. Fractured surface of interior edge of the last molar. 

 ff. Ground surface of outer edge of the same. 



Figs. 11, 12, and 13. Plagiaidax BecMesii. Fragments consisting of 

 the anterior portion of the right ramus of the lower jaw, 

 magnified 2 diameters; fig. 11, outer surface; fig. 12, inner 

 surface ; fig. 13, vertical view seen from above ; a, incisor ; 

 pin, premolars ; b, symphysial harmonia ; c, mentary foramen. 



