281 SYSTEMATIC PALEONTOLOGY 



The shape is quite variable according to the conditions of growth; 

 shell moderately or markedly convex, produced and truncated or atten- 

 uated posteriorly; striae not regular but somewhat irregular and chang- 

 ing into shallow undulations, those on the dorsal and posterior slopes 

 meeting at nearly a right angle; left valve with a flat tooth internally 

 smooth, externally slightly grooved' and fitting into a well marked fosset 

 in the right valve, which is bounded anteriorly by a slight ridge. 



A remarkably fine large specimen from Jones Wharf measures in 

 length, 18 mm.; height, 11 mm.; diameter, 4 mm. 



Occurrence. — Choptank Formation. Governor Kun, Jones Wharf, 

 Pawpaw Point, Greensboro. Calvert Formation. Plum Point. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Genus PARAMYA Conrad. 



pARAMYA SUBOVATA Conrad. 



Plate LXVIII, Figs. 7, 8. 



Myalina subovata Conrad, 184.5, Fossils of the Medial Tertiary, p. 65, pi. xxxvi, 



tig. 4. 

 Paramya subovata Conrad, 1860, Proc. Acad. Nat. Sci. Phila., vol. xii, p. 233. 

 Faramya subovata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 573. 

 Paramya subovata Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 13. 

 Paramya subovata Dall, 1889, Bull, xxxvii, U. S. Nat. Mus., p. 70. 

 Paramya subovata Dall, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 861. 



Description. — " Subovate, inequilateral, ventricose over the umbonal 

 slope, slightly flattened from beak to base; surface with irregular con- 

 centric lines; ligament and basal margins straight, parallel; a spoon- 

 shaped fosset in each valve, the lateral margins of which are carinated; 

 fosset emarginate at base." Conrad, 1845. 



Basal and ligament margins not parallel but divergent posteriorly. 

 Quite rare. 



Length, 5.5 mm. ; height, 4 mm. ; diameter, 1 mm. 



Occurrence. — Choptank Formation. 2 miles south of Governor 

 Eun, Jones Wharf. Calvert Formation. Plum Point. 



Collection. — Maryland Geological Survey. 



