Che Conchologists Exchange. 
COPYRIGHT SECURED. 
Mor. lls 
CHESTNUT BILL, PHILADELPHIA, PA., NOVEMBER, 1887. 
No. 5. 
A Monthly Publication designed for Conchologists and Scientists 
generally. Wm. D. Averell, Editor and Publisher. + 
THE SHELL-BEARING MOLLUSCA OF 
RHODE ISLAND. 
BY HORACE F. CARPENTER. 
Chapter XLI. 
FAMILY CORBULID/L. 
This family contains seven genera of shells 
with more than one hundred species. Two of 
these genera are represented in New England, 
each by a single species. 
Genus Corbula, Brug.—1792. 
The Corbulas or Basket-shells have one valve 
smaller than the other; the animals have a foot 
shaped like a finger, adapted to poke in the 
*sand and mud. ‘The shells are shaped like 
very young Mya’s, but do not gape like them. 
There are seventy-three recognized species, one 
of which inhabits Rhode Island. 
150.—Corbula contracta, Say. 
Shell small, ovate-globose, white (covered 
with smooth, rounded, elevated, concentric 
lines,) shortest and rounded before, narrowed 
_and pointed a little behind; basal margin con- 
contracted and arched in the middle; hinge 
with one slender, upright tooth in each valve, 
fitting into a corresponding pit in the other; 
beaks prominent, inclined forwards; an angu- 
lar ridge runs from the beaks to the posterior 
end defining a broad rhomboidal space; left 
valve smaller than the right. Length, two- 
fifths of an inch; height, one-quarter ; breadth, 
one-fifth. 
This species was described by Thomas Say, 
Journ. Acad. Nat. Sci., Phila., ti, 312, 1822. 
Inhabits from Cape Cod to Florida. is said 
to be veryabundant in some places near low 
water in sand andmud. Perkins says he has 
dug it up alive from sand at low water near 
Savin Rock, New Haven, Conn.  Verrill finds 
it in Vineyard Sound and Buzzard’s Bay in 
five to nineteen fathoms. Gould says it is 
abundant about Rhode Island, but I have not 
been fortunate enough to discover any of these 
large deposits; one living specimen obtained 
in dredging in the bay and two dead ones on 
shore is all that have rewarded my labors thus 
far. 
These shells might easily be mistaken for 
very young clams, but a close examination will 
disclose a very important feature, the right 
valve being larger than the left, the smaller 
valve shuts into the larger one when the shell 
is closed. I believe no other New England 
shell exhibits this peculiarity. 
Genus Nezra, Gray—18384. 
These beautiful shells are shaped like Corbu- 
las, but are provided with a produced rostrum 
or snout at the posterior end, to shelter the deli- 
cate fringed syphonsof the animal. The shells 
are thin and pearly, and are found only in deep 
water. There are twenty-two species, one of 
which inhabits New England. 
151.—Neera pellucida, Stimp, 1854. 
Shell small, thin, sub-ovate, expanded before 
and contracted behind into ashort snout ; beaks 
small, placed a little in front of the middle ; 
surface pale white, smooth with faint striz of 
growth, quite distinct on the rostrum, interior 
smooth and glossy; teeth minute; epidermis 
white, sometimes pale greenish on the beaks 
