FAUNA OF OETHAULAX PUGNAX ZONE. 119 



are smooth and rather smaller ; length of figured specimen 35, height 

 15, maximum diameter 20 mm. 



Tampa silex beds at Ballast Point, Tampa Bay, Florida; E. J. 

 Post. U. S. Nat. Mus. No. 165175. 



Like the other typical Arks this species has a marked byssal gape, 

 and being a nestler shows more or less individual variation of form 

 due to 8itus. 



ARCA PARATINA Dall. 



Area paratina, Dall, Trans. Wagner Inst., vol. 3, pt. 4, p. 623, pi. 33, fig. 14, 



1898. 



Oligocene of the Tampa silex beds at Ballast Point, E. J. Post; 

 of the Chipola River marls, near the Calhoun County bridge, and of 

 the lower bed at Alum Bluff, on the Chattahoochee River, Florida, 

 Dall and Burns. U. S. Nat. Mus. No. 165177. 



Subgenus BARBATIA (Gray) Adams. 



Barhatia Gray, Syn. Brit. Mus., 1840, nude name; Proc. Zool. Soc. London, 

 for 1847, p. 197.— H. and A. Adams, Gen. Rec. Moll., vol. 2, p. 534, 1857. 

 Type, Area Mr'bata Linnaeus. — Dall, Trans. Wagner Inst., vol. 3, pt. 4, 

 p. 615, 1898. 



Section CALLOARCA Gray. 



Calloarea (Gray) H. and A. Adams, Gen. Rec. Moll., vol. 2, 1857, p. 535. 

 Sole example. Area alternata Reeve. — Dall, Trans. Wagner Inst, vol. 3, 

 pt. 4, pp. 615, 623, 1898. 



BARBATIA (CALLOARCA) MARYLANDICA Conrad. 



Plate 4, fig. 3. 



Byssoarca marylandica Conrad, Fossils Medial Tert., p. 54, pi. 29, fig. 1, 



1840. 

 Barhatia marylandiea Conrad, Proc. Acad. Nat. Set. Phila., for 1862, p. 580, 



1863. 

 Barhatia (Calloarea) marylandica Dall, Trans. Wagner Inst., vol. 3, pt. 4, 



p. 623, 1898. 



Oligocene of the Tampa silex beds at Ballast Point; of the lower 

 bed at Alum Bluff, Chattahoochee River ; of the Chipola marls, Cal- 

 houn County, Florida; and of the marls of Jericho, Cumberland 

 County, New Jersey. Miocene of Plum Point, Calvert Cliffs, and 

 Centerville, Maryland; Willcox, Burns, Dall, and Harris. U. S. 

 Nat. Mus. No. 165176. 



This species may possibly occur also in the Jacksonian Eocene of 

 Mississippi. 



BARBATIA (CALLOARCA) IRREGULARIS Dall. 



Plate 17, fig. 4. 



Barhatia {Calloarea) irregularis Dall, Trans. Wagner Inst., vol. 3, pt. 4, 

 p. 623, pi. 33, fig. 5, 1898. 



