1 65 Bulletin 29 330 



anterior and posterior ribs are lacking. In the shell described 

 the ribs on the anterior and posterior slopes are no larger than 

 on the rest of the valve. The ribbing is almost identical with 

 that of A. marylandica Conrad, which is typical of the Maryland 

 Miocene, but also occurs in the Oligocene Tampa silex bed. As 

 exceedingly few species are common to the latter horizon and to 

 the blue clays of Santo Domingo an absolute specific identity 

 seems, however, improbable. 



Localities. — (Exp'd '16) Guayubin to Mao road; Zone H, 

 Rio Cana at Caimito. 



Barbatia (Acar) reticulata Gmelin 



Plate 30, Figure 16 



Area reticulata Gmelin, Syst. Nat., vol. 6, p. 331 1, 1792. 

 A rcr reticulata Sheldon, Palseontographica Americana, vol. 1, p. 20, 

 pi. 4, figs. 8-12, 19:6. 



This richly sculptured Ark is very rare in the Dominican 

 blue clays, in which it has never before been found. It occurs as 

 a fossil at Bowden, Matura (Trinidad), Tampa silex bed, Chip- 

 ola marls and elsewhere and is now living in the Antilles. 



Locality. — (Exp'd '16) Bluff 3, Cercado de Mao. (A single 

 valve). 



Subgenus Noetia Gray 



Section Sheldonella, new section 



Noetia {Sheldonella) maoica, n. sp. 



Plate 30, Figures 17, 18 



Shell small, thin; sculpture as in N. incite or typical limtda; 

 hinge and cardinal area as in Noetia; the anterior half of the 

 ligament area with transverse grooves; ligament area extending 

 about half way from the beaks to the posterior end of the hinge; 

 inner margin crenulated; posterior margin with an angle near 

 the hinge as in N. bisulcata and typical limula; shell probably 

 equivalve. The striking feature of this shell is its form. The 

 umbonal ridge is not angular as in the rest of the No'etice, but 



