188 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 93 



T] e type, U.S.N.M. No. 517058, was dredged off Peanut Island, 

 northern Lake Worth, Fla., by Ted Bayer. It measures: Length, 

 G.5 mm. : height, 4.8 mm. 



This, the second known species of Oooperella, extends the range of 

 the genus into the Antillean region. It differs from the type, O. 

 suhdiaphana Carpenter of the west coast, by being smaller, more 

 translucent, and more equilateral. 



Genus PITAR Romer, 1857 



Nanopitar, new subgenus 



Shell small, suborbicular, externally smooth. Left posterior car- 

 dinal thin, high, joined in part to the ligamental nymph, lower part 

 free, curving awa}? and almost reaching end of hinge plate; left 

 middle and anterior cardinals united at top. The right cardinal 

 separate, the middle cardinal rather stout, parallel to the anterior 

 one, posterior cardinal strong, bifid. Pallial sinus moderately deep, 

 rounded. Ventral margin smooth. 



Genotype: Pitar (Nanopitar) p/'li/Ja, new species. 



This subgenus differs from the other subgenera of Pitar in being 

 smaller and more rounded and in being smooth externally. In the 

 characters of the hinge and pallial sinus it is close to Calpitaria 

 Jukes-Browne and Tinctora Jukes-Browne; from the latter it differs 

 in having a smooth internal ventral margin. From Calpitaria it 

 differs in having a smooth external surface and in being more 

 orbicular. 



PITAR (NANOPITAR) PILULA, new species 



Plate 19, Figttkes 5-10 



Shell small, suborbicular, umbones subcentral, rather prominent, 

 prosogyrate, external surface smooth, covered with a thin yellow- 

 brown, deciduous periostracum. An incised line outlines the other- 

 wise undifferentiated broad lunule. Ligament attached to an 

 elongate sunken nymph. In the left valve the posterior cardinal is 

 for (lie most part confluent with nymph, separating near the lower 

 end and almost reaching the edge of the. hinge plate; median tooth 

 slightly broader than the anterior cardinal and joined to it at right 

 angles under the umbo; anterior lateral strong, erect. In right 

 valve the upper anterior lateral is slightly smaller than the lower 

 (Hit. from which it is separated by a pit, which is connected with the 

 first cardinal interspace by a narrow channel at the base of the an- 

 terior cardinal; cardinals all separate. Anterior cardinal short, thin, 

 parallel to the slightly broader median cardinal; posterior cardinal 

 elongate, rather broad, bifid. Pallial sinus moderately deep, rounded. 

 Internal ventral margin smooth. 



