72 BUI.LET1N 31 72 



Yoldia claibornensis Conrad, PI. 25. Fig. 24. 



Nuciila ciaiboruensis Con., Jr. Phila. Acad. Nat. Sci., vol. i, p. 131, pi. 



14, fig. 22. 

 Yoldia claiboniensis DaXX, Trans. Wag. Ill, 1898, p. 594, 596. 



Conrad's original description. — Ovate-acute, compressed, polished, 

 entire ; ligament and anterior dorsal margin nearly rectilinear ; anterior 

 side longest ; posterior end regularly rounded ; anterior basal margin nearly 

 straight. Locality, Claiborne, Alabama. 



We have heretofore been accustomed to refer the large Yol- 

 dias at the base of the bluff at Claiborne to claibornensis. 



But in the National Museum Collection there are small, 

 smooth specimens from the sand bed which Dall evidentl}^ re- 

 gards as the true claibornensis. In this he is probably correct as 

 Conrad seems not to have collected at all carefully from the St. 

 Maurice bed at the base of the bluff. But the type is lost and it 

 impossible to know for certain from which horizon Conrad's 

 .specimens came. If tho.se derived from the lower horizon are not the 

 .same species as those from the "sand", clearlj^ they should be 

 given a distinctive designation. Dall accordingly names the 

 lower, psammotcea (see below, by a .slight lapsus referred to the 

 "Claiborne sands", p. 596, op. cit.). 



We have no specimens from the Claiborne horizon. 



Yoldia psammolaea Dall, PI. 25. Figs. 25-31 



}'. psatninotcea'Da.W, Trans. Wag., Ill, 1898, p. 596, pi. 34, fig. 20. 



DalVs original description . — Shell smooth, or with faint incremental 

 lines, inequilateral with low beaks, the dorsal and ventral margin sub-par- 

 allel ; valves elongated, rounded in front and behind, the posterior part 

 somewhat compressed and attenuated ;' anterior end with a moderate gape ; 

 lunule and escutcheon elongated, very narrow, almo.st linear. 

 IvOng. 21, alt. 9, diam. 6 mm. 



This species is represented by two specimens with the valves closed 

 and filled with a rather hard matrix, so that the hinge characters are in- 

 accessible. It is clearly di.stinct from any of the described species of the 

 American Eocene, and peculiar in its elongate solenoid form. It cannot be 

 confounded with ]'. claibornensis QonraA, from the same horizon. It would 

 find a place in the section OrtJioyoldia Verrill. 



By a slight confusion of horizons Dall refers this to the 

 Claiborne sand instead of the St. Maurice calcareous clays at 

 the base of the bluff whence it actuallv came. 



