604 PROCEEDINGS OP THE NATIONAL MUSEUM. 



ter, 45 mm. (double). Of these, one has 31 ribs and 5 have 30. Some 

 of them show wider interspaces betAveen radial ribs than t^^pe. 



This subspecies differs from other forms of A. staminea Say, in 

 having a straighter base hue and more extended posterior edge. The 

 ribs are squarer and show less tendency to be divided by longitudinal 

 incised hues. The specimen ^ is the type of A. staminata Dall. Fig- 

 ure 13 is Mocene in age, and closer related to A. staminea than A. 

 staminata. See also for comparison fig. 10 on plate 113. 



LEDA CHOCTAWHATCHEENSIS, new species. 



Plate 113, figs. 2, 4. 



Shell small, solid, subequilateral. The sculpture consists of 11 

 concentric, somewhat lamelliform ribs, which are finer and closer 

 spaced near the beak and coarser, with wide interspaces, and very 

 prominent over the middle of the disk. Anteriorly these lamellae 

 become flattened and reflected bcakward, but obsolete near a faintly 

 indicated posterior ray. The large depressed escutcheon is set off by 

 a nearly smooth carina, extends to the end of the rostrum, and is 

 crossed by four low thread-like longitudinal fines . The narrow elongate 

 lunule is set off by a broken ridge formed by the abruptly tapering 

 of aU of the concentric lameUiform ribs except three which continue 

 as low, nearly longitudinal fines over the lunule. Anterior end 

 romided and much shorter than posterior; posterior end roundly 

 pointed; base broadly rounded. There are 14 teeth on each side of 

 the triangular-shaped chondrophore. The interior of valve has 

 three concentric rounded folds corresponding to the depressions of 

 the exterior sculpture. 



Type (Cat. No. 166916 U.S.N.M.).— This measures— length, 5.4 

 mm.; height, 3.2 mm.; diameter (double), 3.2 mm. 



This species is closely related to Leda trocJiilia DaU, but has coarser, 

 wTider spaced, and more prominent concentric ribs over the middle 

 of the disk; a better defined lunule; absence of a depressed anterior 

 ray; lack of sculpture on posterior ray; a nearly smooth escutcheon 

 carina; and a more broadly rounded marginal base. 



TyiJe-locality. — Mocene of Florida, E. Gomilfion's field, one-fourth 

 mile cast of Redbay, Walton County. C. Wythe Cooke, cofiector. 



PHACOIDES (PLEUROLUCINA) CHOCTAWHATCHEENSIS, new species. / 



Plate 113, figs. 5, 6. / 



SheU sofid, suborbicular, slightly obfique, moderately c^^'^ex, 

 height and length nearly equal; anterior dorsal margin ^y^^^ ^^" 

 sloping at a lower angle than the posterior dorsal margin ; ^Ja-sai mar- 

 gin rounded and sfightly undidated; beak smaU, prosogm'^e and 

 partly overhangs smaU depressed lunule; ligamental area de pressed, 



1 Trans. Wagner Free Inst. Sci., vol. 3, pt. 4, pi. 31, fig. H- 



