PLATE IV 



Fig. 1-18. . .Exogyra arietina Roemer. Del Rio clay. 



Shoal Creek, at Austin, Texas Page 17 



Fig. 1-3 . . adult normal specimen shown in 



three positions. 

 Fig. 4-6. .adult normal specimen shown in 



three positions. 

 Fig. 7-9 . . adult normal specimen shown in 



three positions. 

 Fig. 10-12. .young normal specimen shown in 



three positions. 

 Fig. 16-18. .adolescent stage shown in three 



positions. 



