PLATE 20 



Figs. I, la, lb. Perissognathus adunciis, n. g., n. sp. T}^e. Right mandible in 

 matrix; outer view. Natural size. E 2397, p. 81. 



I a. Symphyseal region of type, showing the row of upturned symphyseal den- 

 ticles. Natural size. 



lb. Another view of same. 



Fig. 2. Small element, probably a lateral of an indeterminate Arthrodire. Nat- 

 ural size. E 1988, p. 97. 



238 



