62 
TE, CONCHOLOGISIS): EXCHANGE: 
and: brownish on the rostrum. Length, one- 
half an inch; height, three tenths, breadth, 
one-fifth. 
This, the first andonly species of this genus 
found on the Atlantic coast of North America, 
is accredited to New Brunswick in Conrad’s 
*« Catalogue of the Family Anatinidze.” ‘*New 
England, northwards,’ Tryon’s Am. Mar. 
Conch. 141. "in Family Myide. Now placed 
in Family Corbulidz. It was described by 
Wm Stimpson, in a pamphlet entitled “ The 
Inyertebrataof Grand Manan” in 1854. A spe- 
cimen@was taken from a haddock caught near 
Portland, Me. Another specimen was brought 
up by the dredge, off Long Island, from forty 
fathoms of water, in mud. 
FAMILY ANATINIDA, D’Orb., 1845. 
This is an immense family, containing thirteen 
living and twenty-six fossil genera. There 
are about 140 species living and over 400 fos- 
sil. There are five genera represented in New 
England. 
Genus Pandora, Brug.—1792. 
Shell inequivalve, thin, pearly within; right 
valve flat; left valve convex; syphons of the 
animal short, united, separated .only at the 
tips. 
152.—Pandora trilineata, Say, 1822. 
Syns : » 
Pandora nasuta, Sby. Clidiopnora trilineata, 
Carp., 1864. 
Shell oblong - ovate, pearly white, round- 
ed before and with an ascending or re- 
curved tip behind; valves nearly flat, the left 
valve a little convex and the right one flat, 
leaving so little space that a novice would hard- 
ly believe that an animal could live between 
them; hinge placed at the posterior slope, 
which is very abrupt, and forms an obtuse an- 
gle with the hinge margin; hinge margin 
bounded on the edges by two rounded, elevated 
lines originating at the beaks and continued to 
the tip; there is also another faintly impressed 
line running across the valve from the beak to 
the middle of the base; on account of the pres- 
ence of these three lines, Say gave it its speci- 
fic name ; Sowerby also named it nasuta, from 
its tip which resembles an upturned nose. 
There are three teeth in the left or convex valve 
and two in the right or flat one ; interior irides- 
cent. Length, one and three-tenth inches; 
height, seven-tenths ; breadth, one sixth. 
A single valve of one of these shells was 
found by Say in Great Egg Harbor, N. J.; he 
afterwards found specimens in Georgia and 
Florida, and described them in the Journ Acad. 
Nat. Sci, Phila., 11: 261, 1822. It has been 
found as far North as Eastport and Grand 
Manan. Common in Buzzard’s Bay, Long 
Island Sound, ete. Gould says: ‘ Found 
about the sazdy regions of Cape Cod, and not 
unfrequently discovered adhering to oysters in 
the market.” We certainly have as good op- 
| portunities for examining oyster shells in Provi- 
dence as in any section of the country, but I 
have never been able to find one of these shells 
adhering to an oyster, nor have any specimens 
been discovered on any of our sazdy shores in 
Narragansett Bay. The only place where we 
find it is off Rumstick, at the mouth of 
Warren river, in fifteen to twenty fathoms wa- 
ter; the bottom here is soft mud, being the de- 
bris brought down by the Warren and Barring- 
ton rivers and deposited along the bottom of the 
Bay for half a mile or more from its mouth. In 
this fine mud live several species of shells not 
found except in similar situations. 
Genus Thracia, Leach—1824. 
There are twenty-seven species of this genus, 
two of which may inhabit Rhode Island. 
153.—Thracia Conradi, Couthouy, 1838. 
Shell rounded-ovate, thin, light and fragile, 
posterior end narrow and truncated; beaks 
nearly central, very conspicuous, that of the 
right valve perforated to receive the point of 
the other; exterior ashy white with a_ thin 
brownish epidermis not covering the whole sur- 
face; surface rough, coarsely wrinkled by the 
lines of growth, underneath it is pearly ; interior 
chalky -white ; valves toothless, held together 
by the strong external ligament; right valve 
large and more convex that the left. Length, 
three to four. inches; height, two and ahalf; 
breadth, one and a half, 
