376 SYSTEMATIC PALEONTOLOGY 



Description. — "' Auricles equal ; surface with from one hundred and 

 forty to one hundred and eighty elevated longitudinal lines. 



" Shell suborbicular, compressed, with very numerous, regular, ele- 

 vated striae, which are muricated with minute scales formed by transverse 

 wrinkles, that are sparse in the middle of the length, and crowded each 

 side of the shell; the intervening spaces are regularly concave, and in 

 parts very distinctly wrinkled : auricles equal, striated like the general 

 surface: within simple, margin striated." Say, 1824. 



This flattened, thin, finely striated shell is very rare in Maryland. 

 It is given on the authority of Dr. Foreman who gave no locality, how- 

 ever. No other one has reported it from the State. 



Length, about 100 mm.; width, rather more (Say). 



Pecten (Chlamys) marylandicus Wagner. 

 Plate XCIX, Fig. 6. 



Pecten Marylandicus Wagner, 1839, Jour. Acad. Nat. Sci. Phila., voL viii, 1st ser., 

 p. 51, pL [3], fig. 3. (Possibly printed privately in 1838.) 



Pecten tenuis H. C. Lea, 1845, Trans. Amer. Philos. Soc, vol. ix, p. 246, pi. xxxv, 

 fig. 33. 



Pecten Marylancliciis Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 581. 



Pecten tenuis Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 581. 



Pecten marijlandicus Meek 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 4. 



Pecten tenuis Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 4. 



Pecten {Placopecten ?) marijlandicus Dall, 1898, Trans. Wagner Free Inst. Sci., vol. 

 iii, pt. iv, p. 738. 



Description. — " Shell ovate, compressed ; ribs numerous, consisting of 

 narrow, nearly smooth striae, disposed in pairs; interstitial spaces each 

 with a carinated line; ears unequal; inferior valve very slightly convex; 

 ribs similar to those of the opposite valve; inner margin of the valve 

 with profoundly elevated lines. 



'' This Pecten is allied to Pecten Madisonius Say, but can readily be 

 distinguished by its want of broad, elevated ribs, and a surface destitute 

 of scales " Wagner, 1839. 



A comparison of numerous specimens shows that the lower valve is 

 more convex than Wagner's description would indicate. The upper 

 valve is but slightly convex, and its ear has the byssal notch well marlced. 

 The interior of each valve is gently fluted in harmony with the external 

 ribs. 



