2 PROCEEDINGS OP THE NATIONAL MUSEUM vol.80 



AGAR BAILYI, new species 



Plate 1, five central figures 



Shell small, rhomboidal, rather inflated, white, with a buflfy tinge. 

 The tips of the umbones are at the posterior extremity of the an- 

 terior fourth of the shell. The umbones are strongly curved and 

 separated only by a narrow space. The cardinal area is narrow and 

 marked by a few slender incised lines, which parallel the hinge 

 margin. The anterior margin of the shell is well rounded. The pos- 

 terior margin is less strongly rounded and somewhat produced at 

 the junction of the posterior and ventral border. The sculpture of 

 the exterior consists of numerous radiating cords, of which 9 

 occur on the anterior portion and 13 upon the posterior part, while 

 23 are present on the middle. In addition to the radiating cords, 

 which increase in strength from the umbone toward the ventral mar- 

 gin, the valves are marked by concentric lamina, which render the 

 cords tuberculated. The anterior ventral and posterior borders of 

 the valves are rendered wavy by the external sculpture at the edge. 

 The interior of the shell is while with a buffy tinge, particularly so 

 in the umbonal region. The muscle scars are large, smooth, and de- 

 cidedly elevated. The teeth of the hinge are few, 8 being present in 

 the anterior group, which slope anteriorly, and 10 in the posterior 

 group, which slope posteriorly. The central of these tooth groups 

 are mere dots, and they increase in size in both directions as shown 

 in our figure. 



Type. — U.S.N.M. No. 382474 is an adult specimen collected by 

 A. M. Strong under stones at Balboa, Calif, It measures: Length, 

 8.8 mm. ; height, 4.9 mm. ; diameter, 4.5 mm. U.S.N.M. No. 347810 

 contains 48 topotypes received from the same source; U.S.N.M. No. 

 74831 contains 11 specimens from San Diego, Calif., from the Stearns 

 collection, and U.S.N.M. No. 74830 contains 3 specimens from San 

 Diego, collected by Henry Hemphill; U.S.N.M. No. 63302 contains 

 4 specimens collected by Doctor Dall ; U.S.N.M. No. 127242 contains 

 2 specimens collected by Mrs. Oldroyd. 



Remarks. — This species was named in our collection Area gradata 

 Broderip and Sowerby, and Fossularca solida Sowerby. From the 

 first it can at once be distinguished by its size. A glance at our 

 figure will also give other distinguishing characters, and from Fos- 

 sularca solida Sowerby by its entirely different ligamental structure. 



AGAR GRADATA (Broderip and Sowerby) 



Plate 1, five top figures 



1829. Area gradata Brodekip and Sowerby, Zool. Journ., no. 15, pp. 365-366. 



Shell moderately large, white with yellowish tinge, rhomboidal 

 with the umbones about opposite the anterior third of the shell. 



