KIMMERIDGIAN PLIOSAURS. 



155 



Table op Admeasurements. 



In PUosaurus grandis the number of alveoli on each side of the uppei' jaw is 

 twenty-seven or twenty-eight. The first pair (PL 19, fig. 2) are terminal and 

 approximate ; the outlet of each measures 1 inch 3 lines in long diameter, which 

 lies in the axis of the jaw : the second alveolus with au outlet 1 inch 9 lines 

 in long diameter, which is transverse to the jaw's axis, is divided by a partition 

 of 4 lines breadth from the first : the third socket is divided by a partition 

 half an inch in breadth, from the second; its outlet is circular, and 2 inches 

 in diameter : the fourth socket is of similar size, and at rather less distance 

 from the third : the fifth socket is less in transverse diameter than the third, 

 but is equal in fore-and-aft diameter to the fourth, from which it stands 9 lines 

 apart. These five pairs of alveoli are in the premaxillary bones (22), and occupy the 

 whole of their alveolar extent. An interval of rather more than two inches inter- 

 venes between the last premaxillary and the first maxillary alveolus, which is the 

 sixth of the series ; and this interval is traversed obliquely by the maxillo- 

 premaxillary suture (PI. 19, fig. 2). The maxillary alveoli have partition walls of 

 about 4 lines in thickness at their fi'ee border ; but these become thinner as the 

 teeth decrease in size in the hinder third part of the series. The alveoli increase 

 in size from the first to the fourth maxillary tooth (ninth of the dental series) ; 

 the longest diameter of the aperture of this socket is 3 inches : thence the alveoli 



