226 



BuivLETTN 39 



398 



CardiuDi ( Trachycardium) domini ce?ise Brov^rx and Pilsbry, 191 1, Proc, 

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



A large species abundant in the Canal Zone but usually only 

 as internal casts. It appears to be rare in Costa Rica, our col- 

 lection containing onlj^ a few fragments of a large individual 

 from East Grape Point Creek. It is distinguished not only by 

 its large size, but very numerous (60+) fine ribs. 

 Gifioi Stoge: Gatu7i, C. Z. 



East Grape Point Creek ^ C. R. 

 Sapote, C. R. {Gabb) 



Cardium costaricanum, n. sp. Plate 27, figure 3 



Shell ovate, solid, inflated; umbos wide and full with high 

 beaks; sculpture of about 24 strong ribs, rounded or subtrian- 

 gular in section with their apex leaning posteriorly except those 

 on the posterior slope which lean anteriorly; interspaces narraw, 

 formed by the sides of the ribs; the ribs are mostly smooth ex- 

 cept those on the anterior half of the shell which have their pos- 

 terior side more or less granulated; this granulation is found al- 

 so on a few of the central ribs near their ventral margin; hinge 

 narrow^; internal margin fluted in harmony with the external 

 ribs. 



Length 24.50, height 34, semi-diameter 15 mm. 

 This species is not uncommon in Costa Rica and may easily 

 be confused with the C. dominicanum Dall. It differs in its 

 larger side, narrow umbos, more pointed beaks and more flatten- 

 ed ribs. 



Gatun Stage: Coll. ^, East Grape Point Creek. 



Subgenus FRAGUM, Bolton 

 Cardium medSum Linnaeus Plate 27, figure 6 



Cardiiim mediuin Linnaeus, 1758, Sys. Nat. ed. 10, p. 678. 

 Cardium medium Reeve, 1844, Conch. Icon., Cardium, pi. 6. fig. 

 30- 



Cardium {Fragum) medium Dall, 1900, Trans. Wagner Free Inst. 

 Sci., vol. 3, pt. 5, p. iioi. 



