88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



Fig. 5. Lateral view (X2) of a left valve with unusually broad plicae; a 



hypotype from the Codell Sandstone Member, Huerfano Park, Colo. 



(locality 59) ; U.M.M.P. 38051. 

 Fig. 6. Lateral view of a left valve (Xl) with a prominent attachment scar; 



hypotype from the Codell Sandstone Member, Huerfano Park, Colo. 



(locality 41, U.S.G.S. 743) ; U.S.N.M. 22011d. 

 Fig. 19. Lateral view (Xl) of a small left valve showing ventral flaring of 



the lateral margins; a hypotype from the Codell Sandstone Member, 



Huerfano Park, Colo, (locality 61) ; U.S.N.M. 132249. 



Lopha bcllaplicata bclIapHcata (Shumard) : forma typica 



Fig. 7. Lateral view (Xl) of a small left valve typical of the species, a 

 hypotype from the Codell Sandstone Member, Huerfano Park, Colo, 

 (locality 40, U.S.G.S. 741) ; U.S.N.M. 22009a. 



Fig. 8. Lateral view (Xl) of a left valve with moderately large attachment 

 scar: a hypotype figured bj' Stanton (1893, pi. 4, fig. 4) from the Codell 

 Sandstone Member, Huerfano Park, Colo, (locality 41, U.S.G.S. 743) ; 

 U.S.N.M. 22860d. 



Fig. 9. Lateral view (Xl) of a left valve, characteristic of the species; hypo- 

 type from the Codell Sandstone Member, Huerfano Park, Colo, (locality 

 61); U.M.M.P. 38038. 



Fig. 10. Lateral view of an unusual left valve (Xl) with abnormally elongate 

 posterior auricle, broad, faint plicae; a hypotype from the Codell Sand- 

 stone Member, Carlile Shale, Huerfano Park, Colo. (locaHty 61) ; 

 U.M.M.P. 43482. 



Fig. 11. Lateral view (Xl) of a mature left valve, slightly longer than 

 average, similar to Texas specimen illustrated on plate 3, figure 12; 

 hypotype from the Codell Sandstone Member, Huerfano Park, Colo, 

 (locality 40, U.S.G.S. 741) ; U.S.N.M. 22009b. 



Fig. 12. Lateral view (Xl) of a typical left valve, a hypotype from the 

 Codell Sandstone Member, Huerfano Park, Colo, (locality 59) ; 

 U.M.M.P. 38039. 



Fig. 13. Lateral view (Xl) of a nearly symmetrical left valve with a large 

 attachment scar and unusually inflated umbone, a hypotype from the 

 Codell Sandstone Member, Huerfano Park, Colo, (locality 41, U.S.G.S. 

 743); U.S.N.M. 22011b. 



Fig. 14. Lateral view (Xl) of a mature left valve with unusually deep 

 attachment scar, abnormally situated dorsoposteriorly ; a hypotype from 

 the Codell Sandstone Member, Huerfano Park, Colo, (locality 59) ; 

 U.M.M.P. 38041. 



Fig. 15. Lateral view (Xl) of a large left valve vvith extended auricles, 

 abnormally broad plicae, and subcentral beak ; a Colorado variant of the 

 species not yet found elsewhere; a hypotype from the Codell Sandstone 

 Member, CarHle Springs, Colo, (locality 55) ; the original of Stanton's 

 plate 4, figure 7 (1893) ; U.S.N.M. 22861. 



Fig. 16. Interior view of a left valve (Xl) showing normal cardinal area, 

 denticles, internal reflection of ornamentation, and posterior adductor 

 muscle scar, the hypotype figured by Stanton (1893, pi. 4, fig. 9), from the 



