396 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [690] 
fine sandy mud; common in Casco Bay and Bay of Fundy, 4 to.100 
fathoms, mud. Greenport, Long Island (8. Smith). Massachusetts 
Bay (Gould). Nova Scotia (Willis). Labrador (Packard). Greenland 
(Morch). 
This species seems to be unknown among our Post-Pliocene shells, 
Having examined several hundred specimens from many different local- 
ities and depths, I am satisfied that it is perfectly distinct from Y. lima- 
tula, with which certain writers are inclined to unite it. 
Yoldia Gouldii. 
Nucula Gouldii DeKay, Nat. Hist. New York, Mollusca, p. 180, Plate 13, fig. 
221, 1343. 
This was originally described by Dekay as from Long Island Sound. 
I have seen no specimens corresponding with the description in all 
respects. Itis, perhaps, a short variety of Y. sapotilla. 
YOLDIA OBESA Stimpson, 1851. (p. 509.) 
H. and A. Adams, Genera, vol. ii, p. 548, 1858; Gould, Invert., ed. ii, p, 155, fig. 
463. Leda obesa Stimpson, Proc. Boston Soc. Nat. Hist., vol. iv, p. 13, 1851 ; 
Shells of New England, p. 10, Plate 2, fig. 1, 1851. Nucula navicularis Mighels, 
Boston Journal Nat. History, p. 323, 1843 (non Couthouy, Gould). 
Block Island to Gulf of Saint Lawrence. East of Block Island, 29 
fathoms, rare; Casco Bay and oft Cape Elizabeth, 30 to 95 fathoms; 
Bay of Fundy, 40 to 100 fathoms, rare; near Saint George’s Bank, 110 
and 150 fathoms (Packard). Massachusetts Bay (Stimpson). 
YOLDIA THRACIFORMIS Stimpson, 1851. (p. 509.) 
Smithsonian Check-List, p. 2, 1860; H. and A. Adams, Genera, vol. ii, p. 548, 
1858 (thracieformis); Gould, Invert., ed. ii, p. 157, fig. 465; Mérch, op. cit., p. 
21, 1457. Nucula thracieformis Storer, Boston Jour. Nat. History, vol. ii, p. 122, 
figure, 1838; Gould, Invert., ed. i, p. 97, fig. 66. Leda thraciaformis Stimpson, 
Shells of New England, p. 9, 1851. Nucula navicularis Couthouy, Boston Journ. 
Nat. History, vol. ii, p. 178, Plate 4, fig. 4, 1839, (voung) ; Gould, Invert., ed. i, 
p. 103. Yoldia angularis Moller, op. cit., p. 92, 1842 (t. Mirch). 
Long Island to Greenland. Off Fire Island, south of Long Island, in 
10 fathoms; and off Race Point, Cape Cod, in 30 fathoms, (Stimpson). 
Not uncommon, and of large size, in Casco Bay, 15 to 95 fathoms; and 
Bay of Fundy, 10 to 100 fathoms; near Saint George’s Bank, 85 fath- 
oms (Packard). 
LEDA TENUISULCATA Stimpson. (p. 509.) 
Shells of New England, p. 10, 1851; Gould, Invert., ed. ii, p. 161, fig. 468. Nucula 
tenuisulcata Couthouy, Boston Journ. Nat. Hist., vol. ii, p. 64, Plate 3, fig. 8, 1838. 
Nucula minuta Gould, Invert., ed. i, p. 101, 1841 (non Fabricius, sp). 
Rhode Island to Gulf of Saint Lawrence. Common in Massachusetts 
Bay, Casco Bay, and Bay of Fundy, 6 to 80 fathoms. Nova Scotia 
(Willis). Newport, Rhode Island (t.S. Smith), Southern part of the 
Gulf of Saint Lawrence (Whiteaves). Particularly abundant in Eastport 
Harbor, 10 to 30 fathoms; Saint George’s Bank and vicinity, 40 to 150 
