HAY— A FOSSIL ALLIGATOR SNAPPER. 455 



EXPLANATION OF THE PLATES. 

 ]\Iacrochelys te.mmin'ckii, fossil. 



Ill the figures of these plates the sutures between the bones are repre- 

 sented by narrow white lines; the seams between the horny scutes by wider 

 dark lines. All the figures are two-fifths of the natural size. 



Plate XVIII. • 

 Fig. I. Skull seen from above. 

 Fig. 2. Skull seen from below. 



Plate XIX. 



Fig. I. Fragment of right side of carapace, c. p. 4, part of fourth costal 

 plate, or bone; behind it is a part of the fifth, mar. 8. mar. g, the eighth mar- 

 ginal horny scute and a part of the ninth, per. 6. per. 7, the sixth and seventh 

 peripheral bones, but only a part of each. .?. mar. 4. the fourth supramarginal 

 horny scute; in front of it is a part of the third. The third costal horny 

 scute area occupies the portions of the costal plates present, except the hinder 

 border of the fifth. 



Fig. 2. Skull seen from the right side. 



