

PLATE IV. 



Page. 



Ostkea lugtjbris Conrad 58 



Fig. 1. A small lower valve from eastern New Mexico. Conrad's type speci- 

 men. 



Nat. Mus. Cat. Invert. Foss., 9822. 

 2. A small upper valve from Huerfano park, Colorado. 



Nat, Mus. Cat. Invert. Foss., 22860. 

 3,5. External and internal views of small lower valves from Mancos, 



Colorado. 



Nat. Mus. Cat. Invert. Foss., 22859. 

 4, 6. Lower valves from Huerfano park, Colorado. 



Nat. Mus. Cat, Invert, Foss., 228G0. 



7. A large lower valve from 20 miles above Pueblo, Colorado. 



Nat. Mus. Cat, Invert. Foss., 22861. 



8. A small lower valve of Osirea bclhurficata from near Sherman, Texas, 



for comparison. Nat. Mus. Cat. Invert. Foss., 11882. 



9. Interior of lower valve from Huerfano park, Colorado. 

 10. Cast of interior of upper valve from same region. 



Nat. Mus. Cat. Invert. Foss., 22860. 



200 



