42 BuivI^ETlN 31 42 



River, 500 yards below the mouth of lyittle Brazos, Tex. Ham- 

 mett's Branch, Sabine River ; Ruston Well, La. 



Var. Carolina. — Three miles and six miles W. N. W. of 

 Orangeburg, S. C. 



Var. abbreviata. — Six miles W. N. W. of Orangeburg, S. C. 



Trinacria declivis Conrad, PI. 19. Figs. 3-6. 



Pedunculus declivis Con., Foss. Sh. Tert. Form., 1833, p. 39. 

 Liniopsis declivis Con., Jr. Phila. Acad. Nat. Sci., vol. 4, i860, p. 297, 



pi. 47, fig. 13. 

 Liniopsis declivis de Greg., Faun. Eoc. de 1' Ala., 1890, p, 191, pi. 23, 



figs. 21-24. ?. 



Trigonoarca declivis 'Dall, Trans. Wag. &c. , III, '94, p. 606. 



Conrad' s original description. — Shell ovate acute, rather compressed, 

 with fine concentric crowded lines, and very minute and obscure radiating 

 lines, which become very distinct on the posterior side, near the extremity ; 

 posterior side cuneiform ; beaks small, pointed and recurved ; series of 

 cardinal teeth interrupted under the beaks ; margin entire. Length 3^ of an 

 inch. 



The posterior basal margin is drawn out characteristicallj'' 

 only in adult forms, the young are nearly quadrate (pi. 19, fig. 5). 

 The exterior markings on this shell are very characteristic. Radii 

 are clearly defined on the posterior portion, but die aw^ay anter- 

 iorly where concentric lines become more prominent, certain of 

 the latter still show a trace of the radiate ornamentation in the 

 form of concentric, microscopic beading. 



This is the abundant and well preserved species of this genus 

 found near the water's edge in the blue clays just above the "Up- 

 per Landing" at Claiborne, — the Cardita de?isala bed of Conrad. 

 Common also at Lisbon, a few miles higher up the Alabama river. 



Types.— Fhilsi. Acad. Mus. 



Specimens figured. — Paleont. Coll. Cornell Univ. 



Trinacria pectuncularls Lea, Pi. 19- Figs. 7-8. 



Nucula pectuncularis Lea, Cont. to Geol., 1833, p. 81, pi. 3, fig. 60. 



Litnopsis peduncularis Con., Jr. Am. Conch., vol. i, '65, p. 12. 



Trinacria pectuncularis T>al\, Trains. Wag. &c.. Ill, '95, p. 577. . 



Lea's original description. — Shell trapezoidal, compressed, nearly 



equilateral, angular before, rounded behind, flattened on the sides, straight 



at basal margin, longitudinally and minutely ribbed ; anterior slope large, 



carinate ; substance of the shell thin ; beaks recurved, pointed ; both series 



