228 



Bulletin 39 



400 



Subgenus PAPYRIDEA, Swainson 



Cardium spinosum Meuschen, var. Turtoni Dall 



Plate 27, figure 



Cardium {Papyrided) spinosum var. Tuftoni 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 spmosum, 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 spinosum in the 

 West Indies and a third variety aspersu77i Sowerby along the 

 Pacific side. 



Gatun Stage: Port Limo7i. 



Cardium serratum Linnaeus, 1758, Syst. Nat., ed. 10, p. 680. 

 Cardium {Lcsvicardium) serratiim 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 {LcFvi cardium) 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 serratum from the West Indies. Others shells are 

 decidely oblique and approach in form the C. sublineatum 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 by its faintly flex- 

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

 al tooth large and strong. 



Subgenus LAEVICARDIUIVl, Swainson 



Cardium serratum Linnseus 



Plate 27, figures 11, 12 



