MARYLAND GEOLOGICAL SURVEY 325 



Sportella pelex Dall. 

 Plate LXXXVII, Fig. 6. 



Sportella pelex Dall, 1900, Trans. Wagner Free Inst. Set., vol. ill, pt. v, p. 1131, 

 pi. xliv, fig. 10. 



Description. — "■ Shell small, solid, compressed, inequilateral, the pos- 

 terior side quite short and blunt; beaks low, surface sculptured with fine, 

 regular incremental lines, of which a few at wide intervals are more 

 conspicuous; basal margin nearly istraight, anterior end produced, 

 rounded, posterior bluntly rounded; left valve with a strong hinge, the 

 anterior lamella obsolete, but the one behind it prominent and strong, 

 socket of the resilium deep, the hinge plate above it obscurely thickened, 

 a narrow but distinct groove for the external ligament; interior polished, 

 the adductor scars rather high up, the disk faintly radially striated, the 

 margin entire. 



"This species has a good deal the shape of a small Mesodesma and 

 is nearest to 8. yorhensis, compared with which it is higher and more 

 inequilateral and with a more oblique anterior dorsal slope." Dall, 1900. 



Length, 7.3 mm.; height, 5.5 mm.; diameter, 2 mm. (Dall). 



Occurrence. — St. Mary's Formation. St Mai-y's River. 



Collection. — Maryland Geological Survey. 



Sportella petropolitana Dall. 

 Plate LXXXVII, Fig. 7. 



Sportella petropolitana Dall, 1900, Trans. Wagner Free Inst. Sci., vol. ill, pt. v, 

 p. 1130, pi. xlv, fig. 10. 



Description. — " Shell small, oblong, subequilateral, moderately con- 

 vex, the dorsal slopes evenly arched, the base nearly straight, and the 

 ends rounded; beaks low and inconspicuous; outer surface nearly smooth 

 or sculptured with incremental lines; hinge with the cardinal tooth 

 single, smooth and conical, the pit small, triangular, and the ligamentary 

 ridge obscure. Lon. 5.75, alt. 3.75, diam. 2 mm." Dall, 1900. 



Occurrence. — Calvert Formation. Plum Point. 



Collection. — U. S. National Museum. 



