MARYLAND GEOLOGICAL SURVEY 283 



Family MYACID/E. 



Genus MYA (Linne) Lamarck. 



Mya peoducta Conrad. 



Plate LXVIII, Figs, la, lb, 2. 



Mya producta Conrad, 183S, Fossils of the Medial Tertiary, p. 1, pi. i, lig. 1. 

 Mya prcBlonga Conrad, 1843, Proc. Nat. Inst, Bull, ii, p. 185, — name only. 

 Mya producta Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xIt, p. .572. 

 3fya producta Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 13. 

 Myaproducta Dall, 1898, Trans. Wagner Free lust. Sci., vol. iii, pt. iv, p. 8.58. 



Description. — " Shell profoundly elongated, elliptical, flexuoiis; 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, 14 mm. 



Occurrence. — Choptank Foemation. Jones "VMiarf. 



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, 



lig. 9. 

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

 Panopcea 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; strise concentric, regular; basal margin straight; beaks promi- 

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

 Lea, 1845. 



