MARYLAND GEOLOGICAL SURVEY 199 



This species occurs infrequently in the Maryland Pleistocene. In the 

 Recent it ranges from Cape Gaspe to the Barbadoes. 



Width, 10 mm.; height, 6 mm. 



Occurrence. — -Talbot Formation. Wailes "Bluff near Cornfield Har- 

 bor, St. Mary's County. 



Collections. — -Maryland Geological Survey, Johns Hopkins University, 

 and U. S. National Museum. 



Genus MACOMA Leach. 



Macoma calcarea (G-melin). 



Telling, calcarea Gmelin, 1792, Syst. Nat. vol. vi, p. 3236. 

 Macoma calcarea Dall, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, 

 p. 1046. 



Description. — " T. testa ovali alba, cardinis dente primario in altera 

 valve fisso, alterius fovese insuto." Gmelin, 1792. 



Only a few fragments of this large Macoma have been found in the 

 Maryland Pleistocene. It is distinctly a boreal type, 'having been found 

 only in high latitudes in the Pleistocene both on the shores of the Atlan- 

 tic and Pacific oceans. In the Eecent it ranges from the Arctic regions 

 in the Atlantic southward to Long Island Sound and in the Pacific to 

 Oregon and northern Japan. 



Occurrence. — -Talbot Formation. Wailes Bluff near Cornfield Har- 

 bor, St. Mary's County; Port Covington, Baltimore. 



Co ZZectftows.— Maryland Geological Survey, Johns Hopkins University, 

 and U. S. National Museum. 



Macoma balthica (Linne). 



Plate LVI, Figs. 7-10. 



Tellina balthica Linne, 1758, Syst. Nat., ed. x, p. 677. 

 Macoma fusca Holmes, 1858, Post-PL Fos. S. C, p. 48, pi. viii, fig. 5. 

 Macoma balthica Dall, 1889, Bull. U. S. Nat. Mus., No. 37, p. 60, pi. lvi, fig. 6. 

 Macoma balthica Dall, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, 

 p. 1051. 



Description. — " T. testa subrotunda Isevi extus incarnata." Linne, 



1758. 



This very common form has been described under various names, 



