NO. 6 OYSTERS OF THE LOPHA LUGUBRIS GROUP — KAUFFMAN 87 



nearly straight dorsal margin, height of smooth stage (greater than on 

 average left valves), the abrupt appearance, prominence, and bifurcation 

 of the plicae, and the well-developed concentric lamellae. Hypotypes 

 from the upper Eagle Ford Shale, 1.5 miles east of Eagle Ford, Dallas 

 County, Tex. (locality 15, U.S.G.S. 7539) ; U.S.N.M. 132236 (fig. 5) ; 

 U.S.N.M. 132237 (fig. 6) ; U.S.N.M. 132238 (fig. 7) ; U.S.N.M. 132239 

 (fig. 8). 



Fig. 9. Lateral view of a right valve from the syntype lot of "Ostrea^' blacki 

 White. Note the only difference between this specimen and typical right 

 valves of L. bellaplicata bellaplicata is the height of the smooth stage. 

 A hypotype of L. bellaplicata bellaplicata from the upper Eagle Ford 

 Shale in Collin County, Tex. (locality 53) ; U.S.N.M. 8024c. 



Figs. 10, 13. Lateral and interior views of an abnormal right valve lacking 

 auricles and prominent plicae. Note nature of cardinal area and muscle 

 scar, both characteristic for the species. A hypotype from the upper 

 Eagle Ford Shale of Texas (locality 57, previously cited) ; U.S.N.M. 

 132240. 



Fig. 11. Lateral view of a nearly smooth right valve of a mature shell, a 

 marginal variant occurring with specimens illustrated in figures 5-8. 

 Compare with figure 12, a syntype of L. blacki (White). Hypotype from 

 the upper Eagle Ford Shale of Texas (locality 15, U.S.G.S. 7539, 

 previously cited) ; U.S.N.M. 132241. 



Figs. 12, IS. Lateral and interior views of a smooth right valve with faint 

 plicae and well-developed interior features. Hypotype of Lopha bella- 

 plicata bellaplicata from the upper Eagle Ford Shale of Collin County, 

 Tex. (locality 53) ; U.S.N.M. 11882b. 



Fig. 14. Lateral view of an unusually elongate right valve with characteristic 

 ornamentation, somewhat worn ; hypotype from the upper Eagle Ford 

 Shale of Dallas County, Tex. (locality IS, U.S.G.S. 7539, previously 

 cited) ; U.S.N.M. 132242. 



Plate 6 

 Lopha bellaplicata bellaplicata (Shumard), variety A 



Fig. 1. Lateral view (Xl) of a typical left valve, showing shape, plicae, 

 narrow beak and umbo, and small attachment scar. A hypotype from the 

 Codell Sandstone Member, Carlile Shale, Huerfano Park, Colo, (locality 

 41, U.S.G.S. 743) ; U.S.N.M. 22011a. 



Fig. 2. Lateral view (X2) of a left valve with an unusually large attachment 

 scar; a hypotype from the Codell Sandstone Member, Huerfano Park, 

 Colo, (locality 59; U.M.M.P. 38052. 



Fig. 3. Lateral view (Xl) of a small plicate upper valve associated with 

 L. bellaplicata bellaplicata var. A ; a hypotype from the Codell Sandstone 

 Member of Huerfano Park, Colo, (locality 58) ; U.S.N.M. 132259. 



Fig. 4. Lateral view (Xl) of a smooth, elongate right valve associated with 

 specimens of L. bellaplicata bellaplicata var. A; a hypotype from the 

 Codell Sandstone Member, Huerfano Park, Colo, (locality 61); 

 U.M.M.P. 43413. 



