NO. 2023. A BRACKISH WATER PLIOCENE FAUNA— BALL. 231 



ANOMIA, sp. indet. 



A large Anomia with irregular radial sculpture, but with the hinge- 

 line and muscular impressions worn away, was obtained with the 

 oysters at station 3614; and at station 6440 an impression, remark- 

 ably like a large Lima, but which is probably due to a distorted 

 specimen of the same Anomia. If the surface sculpture is character- 

 istic it is an undescribed species. 



POTAMIDES MATSONI, new species. 



Plate 21, figs. 1, 2, 7. 



Shell solid, rude, subconic, of about 10 whorls; nucleus small, 

 smooth; spire acute; axial sculpture of incremental lines and numer- 

 ous flexuous low undulations hardly well defined enough to call ribs 

 in average shells but strong and regular in some and obsolete in other 

 specimens. Spiral sculpture of 1 strong posterior and 2 anterior 

 weaker, flattish cords with channeled interspaces, the posterior in- 

 terspace wider and more conspicuous, all surmounted at times by 

 fine spiral threadlets which are frequently absent or obsolete; the 

 rounded base has 6 or more similar cords with wider interspaces, vary- 

 ing in prominence in different mdividuals; aperture subquadrate, the 

 outer lip very flexuous, a wide smus above, the lip patulous on the 

 base, the canal short, very wide and shallow and curved to the left; 

 the pillar very short and the body covered with a smooth callus; the 

 inside of the outer lip smooth. Length of shell 28, maximum width 

 13; width at seventh whorl, counting backward, 2.5 mm. 



Station 6040, near Alexandria, Louisiana, Matson; also at stations 

 3614, 6440, and 6445. Type, U. S. Nat. Mus., No. 166293. 



POTAMIDES MATSONI, var. GRACILIOR new. 



Shell with practicaUy the same sculpture, but more regular and 

 slender, and with the sculpture more uniform. Length 20, maximum 

 diameter of base 7 mm. 



With the typical form but readily separable, and from the same 

 localities, stations 6040, 6440, and 6445. Type, U. S. Nat. Mus., 

 No. 166294. 



CERITmOPSIS? BURKEVELLENSIS, new species. 



Plate 22, fig. 5. 



Shell elevated, rather slender, with about eight whorls exposed, 

 strongly sculptured; suture deep, spiral sculpture of a strong strap- 

 like band immediately in front of the suture, and another behind the 

 next suture; with a rather deep furrow in front of the band; axial 

 sculpture of about 18 strong flattish ribs with narrower interspaces, 

 passing under the furrows at either end, obscurely nodulating the 

 presutural band, and havmg faint indications of a spiral groove divid- 



