.MAliVl.AM) (;i:(>L()(il('.Vl> SL'IIVEY 175 



LUCINA AS'I' AiniKOKMIS Aldricli. 



Plate XX.W II. Kigs. 2, 2a. 



Lnchui iixtartiforinis Aldrirli, 1S',)7, Hull. Aiiht. I'al. Nd. S, p. IT,, ],1. v, lii^s. 1, la. 



Description. — " Slicll smnll. rathrr soiiij; licuk iiniiiicd jiinl siiiiill: >\\y- 

 face witli iiiiiiicrous cuiiccntric raised hiiiicllac wliidi iicarlv ovcrUi]) at 

 vontral iiiai'^in; hctwccii ilu' sii'iac arc Wwv radiating lines I'runi Ijoak to 

 margin: -striae tenninating al hinge line in raised points; hinge long 

 and nai'i'ow; anterioi' of sliidl coneave along the hinge line; esenlclieon 

 smooth; cardinal teeth separated by a deep quadrangidar fosset; no lat- 

 erals; nmsciilar im])ressioiis distinct; ]iallial line simjile; ]iosterior pai't of 

 valves somewhat flattened; mai'gin smooth." Aldi-ich, 189^. 



The nnml)er of raised lanudlae and ilic distance lietwcen tlieui are 

 very. variable factors. This species is very rare. 



Length, 6 mm.; width, 5.5 mm. 



Occurrence. — Nanjejioy Formation". 1 mile southeast of Piscata- 

 way, Upper Marlboro (deep cut near Chesapeake Beach R. R. station). 



Collection. — Maryland Geological Survey. 



LuciNA DAETOxi Clark. 

 Plate XXXVII, Figs. 3, 3a, 3b. 



Lucina clartoni Clark, 189.5, Jobus Hopkins Univ. Circ, vol. xv, p. .5. 



Lucina clartoni Clark, 1896, Bull. 141, T. S. Geol. Survey, p. 79, pi. xx, tigs. 2((-2c. 



Description. — "'■' Shell rather small, suborbicular, thin; surface with 

 fine, thin, distant concentric, lamellated striae, crossed by numerous 

 radial, fine, irregular lines less distant than the concentric lamellae: an- 

 teriorly and posteriorly high shouldered and angulated; lunules large; 

 hinge area narrow; ligament small; muscle impressions shallow; margin 

 simple." Clark, 1896. 



Length. 9 mm.: width. 7.5 mm. 



Occurrence. — Xanjemoy Foemation. Popes Creek, 2| miles above 

 Popes Creek, "Woodstock. 



Collections. — Johns Hopkins laiiversity, Maryland Geological Survey. 



