PLATE V. 



Fig. 17. Inner aspect of the right half of mandible of Amia calva, the Bplenial ele- 

 ment removed. (By the author, after Bridge, somewhat enlarged.) 



Fig. 18. The same view from a specimen in my own possession ; the spleuial element 

 in situ, together with the bones connecting it with the symphvsis. En- 

 larged. (From nature, by the author.) 



104 850 



