86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



attachment scar, and the rounded nature of the plicae (worn), the nature 

 of the valve is identical with those of L. bellaplicata bellaplicata illustrated 

 on plates 3 and 4; hypotype (of L. bellaplicata bellaplicata) from the 

 upper Eagle Ford Shale, Collin Coimty, Tex. (locality 53) ; U.S.N.M. 

 8024a. 



Fig. 2. Lateral view of a large left valve with unusually well developed 

 posterior auricle and faint, worn plicae ; hypotype from upper Eagle Ford 

 sands, 1.75 miles west of Sherman, Tex. (locality 50, U.S.G.S. 14553) ; 

 U.S.N.M. 132229. 



Fig. 3. Lateral view of a typical left valve. Note change in prominence of 

 plicae at midshell, giving rise to faint plicae similar to those on L. blacki 

 (White). A hypotype from the upper Eagle Ford Shale, 2.5 miles east of 

 Eagle Ford, Dallas County, Tex. (locality 15, U.S.G.S. 7539) ; U.S.N.M. 

 132230. 



Fig. 4. Lateral view of an unusually flat left valve with abnormal prosocline 

 inclination, a hypotype from the upper Eagle Ford Shale, Dallas County, 

 Tex. (locality 57) ; U.S.N.M. 132231. 



Fig. 5. Lateral view of an adult left valve showing extensive bifurcation of 

 plicae, and unusually reduced posterior auricle ; a hypotype from the upper 

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

 (locality 15, U.S.G.S. 7539) ; U.S.N.M. 132232. 



Fig. 6. Lateral view of the smoothest specimen from White's syntype lot of 

 L. blacki, considered here a smooth variant of L. bellaplicata bellaplicata 

 (Shumard). The original of White's plate 46, figure 2 (1884). Hypotype 

 from the upper Eagle Ford Shale, Collin County, Tex. (locality 53) ; 

 U.S.N.M. 8024b. 



Fig. 7. Lateral view of a large left valve showing large attachment scar but 

 otherwise typical of the species ; hypotype from the upper Eagle Ford 

 Shale, Dallas County, Tex. (locality 15, U.S.G.S. 7539, cited above) ; 

 U.S.N.M. 132233. 



Fig. 8. Interior view of a left valve showing nature and position of muscle 

 scar, flattened lateral lamellae forming part of commissure, and unusually 

 massive cardinal area with characteristic structures ; a hypotype from 

 the upper Eagle Ford Shale, Dallas County, Tex. (locality 57) ; U.S.N.M. 

 132234. 



Plate 5 

 (All figures Xl) 

 Lopha bellaplicata bellaplicata (Shumard) 



Figs. 1-4. Anterior (side) views of representative left valves, illustrating the 

 range of variation in convexity. No. 1 is typical of the species. 1-3, 

 Neotype and hypotypes from the upper Eagle Ford Shale, Dallas County, 

 Tex. (locality 15, U.S.G.S. 7539) ; U.S.N.M. 132222 (fig. 1) ; U.S.N.M. 

 132228 (fig. 2) ; U.S.N.M. 132235 (fig. 3). 4, Hypotype from the upper 

 Eagle Ford Shale, Dallas County, Tex. (locality 57) ; U.S.N.M. 132231. 



Figs. 5-8. Lateral views of typical right valves, arranged in growth series. 

 Note development of auricles (fig. 7 is atypical in this respect, having 

 rounded auricles), anterior position of beaks, posterior curvature of beaks. 



