84 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 48 



Fig. 8. Lateral view (X2) of a right valve with radiating ornament limited 

 to crenulations in marginal lamellae ; a hypotype from Huerfano Park, 

 Colo, (locality 34) ; U.M.M.P. 43470. 



Fig. 9. Lateral view (X2) of an elongate, nonplicate right valve; a hypotype 

 from Huerfano Park, Colo, (locality 32) ; U.M.M.P. 43487. 



Fig. 10. Lateral view (X2) of a smooth right valve showing reflection of 

 attachment surface (probably an Inoceramus shell) on exterior of upper 

 valve; a hypotype from near Mancos, Colo, (locality 4, U.S.G.S. 833); 

 U.S.N.M. 22211. 



Fig. 11. Lateral view (X2) of a smooth right valve showing nature of 

 growth lines and fine lamellae; a hypotype from Huerfano Park, Colo, 

 (locality 58) in the Juana Lopez Member; U.M.M.P. 43484. 



Fig. 12. Lateral view (X2) of a small right valve with well-developed 

 marginal lamellae, and faint crenulations on the anterior and ventral 

 borders; a hypotype from Huerfano Park, Colo, (locality 33) in the 

 Juana Lopez Member ; U.M.M.P. 43471. 



Fig. 13. Interior view (X2) of a thick right valve showing unusually deep 

 but typically shaped posterior adductor muscle scar, traces of fine 

 radiating incised lines on inner surface of valve ; a hypotype from Rattle- 

 snake Buttes, Colo, (locality 2, U.S.G.S. 747) in the Juana Lopez Mem- 

 ber; U.S.N.M. 22008b. 



Fig. 14. Interior view (X2) of a small right valve with unusually large 

 cardinal area, typical muscle scar, and well-developed denticles (repre- 

 sented by notches) ; a hypotype from Rattlesnake Buttes, Colo, (locality 2, 

 U.S.G.S. 747), in the Juana Lopez Member; U.S.N.M. 22008b. 



Fig. 15. Lateral view (X2) of a typical right valve, nonplicate, and with 

 reverse curvature; a hypotype from Huerfano Park, Colo, (locality 34), 

 in the Juana Lopez Member ; U.M.M.P. 43486. 



Fig, 16. Interior view (X2) of a typical right valve showing nature of 

 cardinal area, well-developed denticles, a typical muscle scar, and fine, 

 sinuous, incised lines on the inner valve surface; a hypotype from the 

 Mancos Shale, San Miguel County, Colo, (locality 28, U.S.G.S. 22592) ; 

 U.S.N.M. 132258. 



Fig. 17. Interior view (X2) of a right valve with unusually large resilifer 

 and muscle scar, well-developed denticles ; a hypotype from near White- 

 water, Colo., from the Juana Lopez Member equivalent in the Mancos 

 Shale (locality 22, U.S.G.S. 13663) ; U.S.N.M. 132165. 



Plate 3 



(All figures Xl) 



Lopha hellaplicata hellapUcata (Shumard) 



Figs. 1, 3, 9, 11, IS, 18. Lateral views of typical left valves of the species, 

 placed in a growth series ; note characteristic outline, nature and extent 

 of auricles and auricular sulci, small attachment scars, nature of plicae and 

 height of smooth stage ; all specimens hypotypes from the upper Eagle 

 Ford Shale, 2.5 miles east of Eagle Ford, Dallas County, Tex. (locality 

 15, U.S.G.S. 7539). Catalog Nos. : 1 (U.S.N.M. 132213), 3 (U.S.N.M. 

 132215), 9 (U.S.N.M. 132220), 11 (U.S.N.M. 132222, the neotype), 

 15 (U.S.N.M. 132225), and 18 (U.S.N.M. 132228). 



