2 28 Bulletin 39 400 



Subgenus PAPYRIDEA, Swainson 



Cardium spinosum Meuschen, var. Turtoni Dall Plate 27, figure i 



Cardiuui {Papyridea) spinosum var. Twtoni Dall, 1900, Trans. Wag- 

 ner Free Inst., Sci., vol. 3, pt. 5, p. 1108. 



The fossil shells from Costa Rica, are referrible to this var- 

 iety of spinosum, distinguished by having the interspaces be- 

 tween the ribs marked with a flat thread, between sharp grooves. 

 This variety is also found fossil in the Chesapeake Miocene at 

 Jackson Bluff Florida and in the Pliocene Caloosahatchie beds of 

 the same state. It the recent fauna it is confined, according to 

 Dall, to the eastern Atlantic, with the typical spmosicm in the 

 West Indies and a third variety aspersuvi Sowerby along the 

 Pacific side. 



Gatun Stage: Port Limon. 



Subgenus LAEVICARDlUiV!, Swainson 



Cardium serratum Linnaeus Plate 27, figures II, 12 



Cardium serratum Linnaeus, 1758, Sj'st. Nat., ed. 10, p. 680. 

 Cardium, [Lczvicardium) serratum Dall, 1900, Trans. Wagner Free 



Inst. Sci., vol. 3, pt. 5, p. mo. 

 Cardium {Lcsvicardium) serratum Brown and Pilsbry, 191 1, Proc 



Acad. Nat. Sci. Phila., vol. 63, p. 367. 

 Cardium {Lcsvicardiuni) serratum Maury, 1917, Bull. Amer. Pal., vol. 



5, p. 376, pi. 36, fig. 8. 



Most of the fossil shells are indistinguishable from recent 

 examples of serratinn from the West Indies. Others shells are 

 decidely oblique and approach in form the C. sutjlineatum Con- 

 rad of the Upper Chesapeake Miocene of eastern United States. 

 The C. venustum Gabb from the Miocene of Santo Domingo is 

 very distinct from serratum and characterized b}^ its faintl}^ fiex- 

 uous outline, strong radial striae, and in having the lower cardin- 

 al tooth large and strong. 



