52 DESCRIPTION OF FIVE NEW FOSSILS. 
hitherto been found ; this I obtained on a visit to 
Porto Bello, on St. Mary’s river, Maryland. 
Panopea Goldfussii. PI. 1 , fig. 3. 
Shell oblong, subovate, ventricose; disks with 
concentric, unequal, shallow grooves; lines of growth 
coarse and prominent ; anterior extremity slightly 
gaping; anterior margin rounded, anterior dorsal 
margin elevated; posterior side narrowed, some- 
what produced, not reflected ; posterior dorsal mar- 
gin nearly rectilinear; cardinal teeth obliquely 
compressed, united at base to the nympha, short 
and not very prominent. 
Locality. Mehering river, North Carolina. Al- 
lied to Panopea reflexa, Say, from which it differs 
in being proportionally more elongated, and without 
reflected margin, in being nearly closed anteriorly, 
and in having a straight dorsal line. 
Mysia nucleiformis. PI. 1 , fig. 4. 
Shell suborbicular, ventricose, lines of growth 
very distinct on the inferior half of the disk ; pos- 
terior margin direct. 
Locality. Mehering river, North Carolina. 
Trociius eborcus. PI. 1, fie 5 
Shell smooth and slightly polished ; spire short 
conical ; whirls flattened laterally, margined above 
by a very obtuse obsolete carina ; spriral lines ob- 
