N0.21G9. MOLLUi^E.S OF CHOCTAWIIATCHEE MARL~MAN8F1ELD. 605 



quite deep, and long; anterior dorsal area slightly depressed and 

 strongly separated from the rest of the surface by a wide shallow 

 groove, which widens distally; posterior dorsal area arched, promi- 

 nent, much larger than anterior, and resembles the first anterior 

 radial rib. Surface with rather coarse raised concentric lamellae, 

 which are shghtly thickened over the radial ribs and dorsally reflected 

 more near the margin and between the radial ribs. On the last half 

 of the disk the lamellae are grouped into series and are separated by 

 wide interspaces, between which are many fhie rounded concentric 

 threads. The radial sculpture consists of four diverging ribs, which 

 are separated by moderately shallow distally widening interspaces. 

 The median interspaces become nearly obsolete near the margin. 

 The inner margin of the valve is crenate. The posterior lateral socket 

 is about one-third the length of the valve from the cardinal teeth; 

 the anterior socket is a little nearer; both are moderately deep and 

 large. The two cardinal teeth are of nearly equal size, the posterior 

 cardinal being a httle eroded, and appears to be shghtly bifid. The 

 anterior socket is small and shallow. 



Type (Cat. No. 166915 U.S.N.M.)— This measures— length, 10.3 

 mm.; height, 9.4 mm.; diameter (double), 7.4 mm. A broken and 

 eroded specimen from the same locahty is a little larger and more 

 mature, but shows better the characteristic wide interspaced areas 

 betv/een the grouped concentric lamellae, which probably represent 

 rapid-growth periods of the shell. 



This species is related to the OHgocene Phacoides (Pleurolucina) 

 quadricostatus Dall, and its closely alUed form, the recent Phacoides 

 leucocyma Dall, but differs from both in being larger and much longer 

 and having a more prominent posterior area. It is less obhque and 

 has a proportionately longer hgamental depression than P. quadri- 

 costatus. It is a httle smaller than the Phocene Phacoides (Pleuro- 

 lucina) amahilis Dall, but appears to be less closely related to it than 

 to either the Oiigocene or recent species above cited. 



This species records its subgenus ''Pleurolucina" for the first time 

 from the Miocene of Florida. 



Type-locality.— Miocene of Florida, E. Gomillion's field, one-fourth 

 mile east of Redbay, Walton County, Florida. C. Wj^the Cooke, 

 collector. 



ASTARTE (ASHTAROTHA) VAUGHANI. new species. 



Plate 113, figs. 8, 9. 



SheU smaU, solid, sub triangular, nearly equilateral; beak mod- 

 erately compressed and acute, inclined a little forward; anterior and 

 posterior slopes nearly straight and of equal length; anterior and 

 posterior basal margins rounded; basal margin broadly rounded; 

 tip of beak smooth; beak sculptured with rounded concentric rib- 



