MARYLAND GEOLOGICAL SURVEY 283 



Family MYAClDy^. 



Genus MYA (Linne) Lamarck. 



Mya producta Conrad. 



Plate LX VIII, Figs, la, lb, 2. 



3Iyu producta Conrad, 183>>, Fossils of the Medial Tertiary, p. 1, pi. i, tig. L 

 Mya prcdotiga Conrad, 1842, Proc. Nat. Inst., Bull, ii, p. 185, — name only. 

 Mya producta Conrad, 1863, Proc. Acad. Nat. Sci. Phila.. vol. xiv, p. .573. 

 Mya producta Meek, 1804, Miocene Check List, Smith. Misc. Coll. (183), p. 12. 

 Mya producta Dall, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 858. 



Description. — " Shell profoundly elongated, elliptical, flexuous; sur- 

 face coarsely wrinkled; beaks prominent, flattened posterior to the mid- 

 dle; base emarginate, corresponding to the furrow on the disk; left valve 

 with obsolete radiating striae; cardinal tooth profoundly dilated." Con- 

 rad, 1838. 



" This is a fine and remarkably elongated species, gaping at both 

 extremities, and very rare." 



We have but one imperfect valve. 



Length, 123 mm.; height, about 50 mm.; diameter, 1-1 mm. 



Occurrence. — Choptank Formation. Jones Wharf. 



Collection. — Maryland Geological Survey. 



Genus SPHENIA Turton. 



Sphenia dubia (H. C. Lea). 

 Plate LXVIII, Figs. 3, 4, 5, 6. 



Panopcea dubia H. C. Lea, 1845, Trans. Amer. Philos. Soc, vol. ix, p. 236, pi. xxxiv, 



tig. 9. 

 Olycimeris dubia Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. .571. 

 Panopma dubia Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 12. 

 Sphenia dubia Dall, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 859. 



Description. — "Shell quadrately elliptical, transverse, inequilateral, 

 posteriorly truncate, anteriorly rounded, somewhat inflated, rather thick, 

 striate; striae concentric, regular; basal margin straight; beaks promi- 

 nent; nympha? large, exserted, very long; hinge with a small fosset." 

 Lea, 1845. 



