333 Dominican Fossils — Maury 169 



Localities. — (Exp'd'16) Zones B, F, G, Rio Gurabo at Los 

 Quemados; ZoneH, Rio Cana at Caimito; Bluff 1, Cercado de 

 Mao. 



Scapharca cercadica, n. sp. 

 Plate 29, Figure 5 



Shell thin and fragile for the group; elegantly and finely 

 sculptured; anterior margin rounded, apparently meeting the 

 hinge at an angle but both ends of the hinge are broken in our 

 single specimen; basal margin nearly straight and parallel to the 

 hinge; posterior margin oblique, not straight but slightly sinuous 

 above, as shown by the growth-lines, and broadly, evenly and 

 gracefully curving into the ventral margin; ribs thirty -four, wider 

 than the interspaces, those anterior to the umbonal ridge very 

 evenly, dichotomously divided for nearly their entire length by a 

 sulcus two- thirds as wide as the interspaces; there are no second- 

 ary grooves except faint traces on the umbonal ridge; posterior 

 ribs smoother and flatter, with a less pronounced incised line; 

 ribs and interspaces crossed by fine, even, close-set, concentric 

 lines; hinge long and narrow, central portion broken. away, distal 

 teeth delicate and short, anterior vertical, posterior no larger 

 than the anterior, barely inclined. Length 50, altitude approxi- 

 mately 25 mm. 



This rare and elegant Scapharca cannot be confused with 

 any of our other Dominican species. 



Locality. — Exp'd '16) Bluff 1, Cercado de Mao. 



Scapharca Margarets, n. sp. 

 Plate 28, Figure 1 



Shell large, oblong, solid, ribs thirty-one, entire, narrower 

 than the concave interspaces and flat-topped or slightly rounded; 

 ribs and interspaces crossed by fine, even, concentric threads 

 forming arches over the ribs and loops in the interspaces; the 

 ribbing is very similar to that of Anadara aresta and A. campsa, 

 from the Florida Miocene; some of the ribs distally show a mere 

 trace of a mesial groove; hinge line long with numerous teeth 

 nearly vertical except at the posterior end where the}' are some- 



