274 SYSTEMATIC PALEONTOLOGY 



margin of the elliptical aperture into four appendages, of which the two 

 small opposite ones are equal, the two larger ones, however, very un- 

 equal." Meyer and Aldrich, 1886. 



Length, 7.5 mm. ; diameter, 1.1 mm. 



Occurrence. — Choptank Formation. Jones Wharf. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



Class PELECYPODA. 



Order TELEODESMACEA. 



Superfamily ADESMACEA. 



Family PHOLADID/^. 



Subfamily PHOLADIN/E. 



Genus PHOLAS (Linne) Lamarck. 



Subgenus THOVANA Gray. 



Pholas (Thovana) producta Conrad. 



Plate LXV, Fig. 1. 



Pholas oblongata Tuomey and Holmes, 1856, Pleiocene Fossils of South Carolina, 



p. 103, pi. xxiv, tig. 5. 

 Not Pholas oblongata Say. 



Pholas producta Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 571. 

 Pholas producta Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 12. 

 Pholas {Thovana) producta Dall, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. 



iv, p. 815. 



Description. — " Shell oblong-ovate, inflated, transversely and longi- 

 tudinally striated; striae muricated, and elevated on the buccal side into 

 ribs; buccal margin acutely rounded; anal margin compressed; dorsal 

 margin anteriorly reflexed, forming a cavity; hinge callous, minutely 

 striated transversely and longitudinally, and with about twelve cells." 

 Tuomey and Holmes, 1856. 



Occurrence. — Choptank Formation. Greensboro. 

 Collection. — Maryland Geological Survey. 



Genus BARNEA (Leach MS.) Risso. 



Subgenus SCOBINA Bayle. 



Barnea (Scobina) arcuata (Conrad). 



Plate LXV, Figs. 2, 3. 



Pholas arcuata Conrad, 1841, Fossils of the Medial Tertiary, p. 3 of cover of No. 2. 

 Pholas acuminata Conrad, 1845, Fossils of the Medial Tertiary, p. 77, pi. xliv, fig. 2. 



