NO. 6 OYSTERS OF THE LOPHA LUGUBRIS GROUP — KAUFFMAN 89 



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

 743); U.S.N.M. 22860b. 



Fig. 17. Lateral view of a typical right valve from Colorado (X2) showing 

 limited extent of plicae, concentric ornamentation, shape; a hypotype 

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

 U.M.M.P. 43466. 



Fig. 18. Lateral view (X2) of a totally nonplicate right valve, otherwise 

 typical of the species; a hypotype from the Codell Sandstone Member, 

 Huerfano Park, Colo, (locality 59) ; U.M.M.P. 43483. 



Fig. 20. Lateral view (Xl) of a large, unusually high right valve, showing- 

 typical development of the concentric lamellae; a hypotype from the 

 upper Eagle Ford Shale, Dallas County, Tex. (locality 15, U.S.G.S. 

 7539) ; U.S.N.M. 132250. 



Fig. 21. Lateral view (Xl) of a nearly smooth right valve showing a few, 

 sinuous, irregular plicae near margin ; a hypotype from the Codell Sand- 

 stone Member, Huerfano Park, Colo, (locality 59) ; U.M.M.P. 43478. 



Figs. 22, 23. Dorsal and posterior views (Xl) of a small left valve with 

 plicae less extensive than average, and an unusually large attachment 

 scar; the hj'potype illustrated by Stanton (1893, pi. 4, fig. 6), from the 

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

 743) ; U.S.N.M. 22860c. 



Fig. 24. Lateral view of a large, old right valve showing degeneration of 

 radial ornamentation near margin, and increase in number and prominence 

 of the concentric lamellae with age; a hypotype from the upper Eagle 

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

 132251. 



Plate 7 

 (All figures Xl) 

 Lopha bellaplicata novamexicana Kauffman, new subspecies 



Figs. 1, 2. Lateral views of immature left valves, typical of the subspecies. 

 Note general similarity to immature left valves of L. bellaplicata 

 bellaplicata (pi. 3) but the smaller auricles and more inclined postero- 

 dorsal margin in the subspecies novamexicana at this and later growth 

 stages. Paratypes from the zone of Colligiwniceras hyatti (Stanton), 

 Mancos Shale, Socorro County, N. Mex. (locality 66, U.S.G.S. D2042) ; 

 U.S.N.M. 132260 (fig. 1), and 132261 (fig. 2). 



Fig. 3. Lateral view of a young adult left valve, typical of the subspecies 

 except for narrow auricular sulci. Note broad plicae. A paratype from 

 the Colorado Group (Mancos?), Carthage, N. Mex. (locality 64, U.S.G.S. 

 3297) ; U.S.N.M. 132262. 



Figs. 4, 5. Lateral and interior views of a typical adult valve showing broad, 

 widely spaced plicae, few in number, inclined posterodorsal margin, 

 broad posterior auricular sulcus, and the nature of the cardinal area and 

 muscle scar. A paratype from the Mancos Shale, Socorro County, N. Mex. 

 (locality 66, U.S.G.S. D2042) ; U.S.N.M. 132263. 



