DESCRIPTION OF PLATE XXXIII. 



Plagiaulax Becklesii. 



The drawings in this Plate have been reproduced from the 

 woodcuts which accompanied the memoir as originally pub- 

 lished in the Quart. Journ. Geol. Soc. for August, 1857. 

 (See page 410.) 



Figs. 1-6. Plagiaulax Becklesii (figs. 1-5), and Hypsiprymnus Gai- 

 mardi (fig. 6). Figs. 1 and 4 show the entire right ramus of the 

 lower jaw, in two pieces, on reversed slabs of the same piece of 

 matrix. Magnified two diameters. 



[Figs. 1 and 4 represent the same right ramus of the lower jaw 

 seen on the opposite surfaces of a split stone, the two taken 

 together affording data for a complete restoration of the jaw.] 



Fig. 1 . a, b, e'. Outer side of the anterior portion of the right ramus of 

 lower jaw ; magnified two diameters, a, b, outer side, b, o', d', e', 

 impression of inner side. 



a. Incisor. 



b. Line of vertical fracture behind the premolars. 

 d'. Impression in the matrix of the condyle. 



e'. Impression of top of coronoid process. 



o'. Broken-off inflected fold of inner margin buried in the 



matrix. 

 m. Place of the two molars. 

 pm. Three premolars, the third or last divided by a crack. 



Fig. 2. f. Section of the anterior piece of the jaw at the fracture, fig. 

 1 b ; x, inner surface ; y, outer. The notch at the top is formed 

 by one of the sockets of the double-fanged true molar. 



Fig. 3. g. Section of the hinder piece near b in fig. 1 ; x, inner surface ; 

 y, outer surface. 



Fig. 4. a', d. Inner side of the posterior portion of the same lower jaw 

 on the opposite slab of stone ; b, d, e, inner side ; b, a', h, cast 

 and impression of outer side. 



a'. Outline of the incisor restored. 

 b. Line of vertical fracture. 

 d. Condyle. 

 . e. Coronoid process. 1 



1 The artist has made the point of the coronoid (c ) project too much back- 

 wards, and the curve of the posterior margin too great ; the line being nearly 

 vertical in the original. The projection of the condyle behind the coronoid margin 

 is more considerable than is shown by the figure, and the neck longer. — H. F. 



vol. ii. e 



