Che Conchologsts Exchange. 
COPYRIGHT SECURED. 
WOVE WIE 
CHESTNUT HILL, PHILADELPHIA, PA., DECEMBER, 1887. 
No. 6. 
a Monthly Publication designed for Conchologists and Scientists 
eee ty. Wm. D. Averell, Editor and Publisher. 
THE SHELL-BEARING MOLLUSCA OF 
RHODE ISLAND. 
BY HORACE F. CARPENTER. 
Chapter XLII. 
Genus Periploma, Schum., 1817. 
Couthouy, in 1839, proposed the names of 
Cochlodesma for this genus in Journ. Bost. Soc. 
Nat. Hist, ii., p.170. Gray, in the ‘‘ Annals 
of Science,” admits the genus, and it has been 
used by Gould, De Kay, Mighels, Chenu., Bin- 
ney, and by Dall as late as 1870, but I follow 
Conrad’s “Catalogue of the Anatinidee” by 
giving Schumacker’s name priority, having 
been proposed and used twenty-two years pre- 
vious to Cochlodesma. ‘There are twelve spe- 
cies, one of which inhabits New England. 
. 
155.—FPeriploma Leana, Con., 1831. 
Syns : 
Anatina Leana, Conrad. Cochlodesma Le- 
ana, various authors. Cochlodesma Leanum, 
Stimpson. Periploma Leana, Con., Tryon, &c. 
Shell thin, sub-oval, inequivalve slightly gaping 
white, with a thin yellowish epidermis; hinge, a 
spoon-shaped process, resting on arib and receiv- 
ing the cartilage; right valve convex, truncate at 
the posterior end; left valve nearly flat and round- 
ed at both ends; interior chalky white, except 
at the muscular and pallial impressions, where it 
is superficially pearly. Length 12, breadth .%,. 
height I inch. Abundant on Cape Cod and 
Nantucket. Inhabits from North Carolina to 
the Gulf of St. Lawrence. Probably inhabits 
the ocean shore of R, I., but has not yet been 
found in Narragansett Bay. 
Genus Lyonsia, Turton, 1822. 
There are eighteen species of this genus dis- 
tributed world-wide, of which one inhabits the 
coast of New England, 
156.—Lyonsia hyalina, Conrad. 
Syns: 
Mya hyalina, Con. Osteodesma hyalina, 
Couth,, Gld., Delay, Migh. Lyonsia hyalina, 
Con , Stimp., Tryon, Perkins, Dall. 
Shell elongated, sub-ovate, thin, very fragile, 
translucent, pearly, inequipartite, the posterior 
end lengthened, narrowed and compressed at 
the extremity, but truncated a little at the tip, 
and gaping; epidermis wrinkled in radiating 
lines from the beak, each line microscopically 
fringed with short hairs, which entangle grains 
of sand; when these shells are found, as they 
sometimes are, completely covered with sand, 
the only way to remove it is to gently agitate 
them in water, as they are too delicate to be 
cleaned by the brush, like most shells. They 
are found in quiet bays where they are not ex- 
posed to the wind and waves, just below low 
water mark in sand. Length 7%, height 7%, 
breadth 33, of an inch Inhabits from Florida 
to the Gulf of St. Lawrence. In April, 1836, 
the beach at Chelsea was covered with thou- 
sands of very large and mature ones, since which 
time only occasional specimens have been 
found. I found on one occasion quite a num- 
ber of specimens near Nayatt, where I have 
examined the shores many times before and 
since without seeing one, and at another time 
I found several large ones at Buttonwoods, but 
on visiting the same place a week or two after, 
not a trace of one could be seen. 
