PLA.TE III. 



Pace. 



FIG. 1. Deltodus Mereurii, Newb., upper surface 137 



la. " " Newb., side view 137 



Coal- Measures, Santa F6", N. Mex. 



FIG. 2. I'tycliofliix Whipiild, Marcou, upper surface 137 



2a. " Marcou, side view 137 



26. " Marcou, anterior face 137 



Se-2/. " " Marcou, side and front view of small teeth 137 



Middle Cretaceous, Pagosa, Southwestern Colorado. 



FIG. 3. Product UK r.odoms, Newb., ventral valve 140 



Ha. " " Newb., side view 140 



3fc,3c. " " Newb., specimen with narrow hinge 140 



'id. " " Nowb., specimen with broail hingo 140 



Coal Measures, Santa Fe, N. Mex. 



FIG. 4. Pleurolomaria excelsa, Newb., side view 



4a. " " Newb., basal aspect 140 



Carboniferous strata, Canon of Colorado River, Southeastern Utah. 



FlO. 5. Spirifer Texanns, Meek, side view, natural size 



f>a. A dorsal view of same specimen, showing cardinal area and foramen 130 



.Vi. A ventral view of a larger specimen, showing the deep angular mesial sinus 139 



