176 cbetaoeous' feiuod. 



Family PECTINID^. 



Genus GAMPTONECTES Meek (Agassiz), 1S64. 



Camptonectes platessa White. 



Plate XVII, fig. 5 a. 



Camptonectes platessa Wliite, 1874, Exp. & Snrv. west 100th Merid., Prelim. Eep. 

 Invert. Foss., 25. 



Sliell thin, suborbicular in outline ; length of hinge-line about equal 

 to one-half the transverse diameter; ears well defined by auricular furrows; 

 posterior ear short, flat, its outer margin slightly concave ; anterior ear 

 moderately large, marked by distinct lines of growth and obscure radiating 

 striae. The anterior ear of the right valve separated from the body-portion 

 by a deep, rather narrow, and somewhat angular sinus, the depth of Avhich 

 is equal to about one-half the length of the ear from its outer extremity to 

 the beak. Radiating striae of the sxxrface moderately fine, increasing in 

 number so rapidly that the direction of the outer ends of those above the 

 middle of the valve is transverse, and farther toward the hinge they are 

 distinctly recurving ; the radiating lines crossed by fine concentric striae, 

 and occasionally by more distinct lines of growth. 



Height and transverse diameter each about forty-five millimeters. 



This species somewhat resembles C. hellistriata Meek and Hayden from 

 the Jurassic strata of Dakota ; but it is proportionally not so broad from 

 front to rear, the ears are proportionally a little longer, and the radiating 

 striae a little coarser. 



Position and locality. — Strata of the Cretaceous period ; fifty miles north 

 of Camp Apache, and five miles west of Mineral Spring, Arizona. 



Family LIMID^. 



Genus LIMA Brnguiere, 1791. 

 Lima W^acoensis Eceiner. 



Plate XVII, fig. 4 a, I), and c. 



Lima Wacoensis RcBmer, 1852, Kreidebildung von Texas, 03. 

 Lima Wacoensis Conrad, 1857, U. S. & Mex. Bound. Surv., i, 151. 



Shell rather small, moderately convex, oblique, irregularly oval in 

 marginal outline ; antero-basal margin broadlv rounded ; posterior margin 



