380 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [674] 
and Buzzard’s Bay (Gould}; Labrador (Packard). Fossil in the Post- 
Pliocene (Leda-clay) at Saco, Maine (Fuller). 
This species burrows so deeply in the mud or sand that it is seldom 
taken alive with the dredge. 
THRACIA TRUNCATA Mighels and Adams. Plate XXVII, fig. 195. (p. 
509.) 
Boston Jour. Nat. Hist., vol. iv, p. 38, Plate 4, fig. 1, 1842; Gould, Invert., ed. ii, 
p. 72, fig. 386. 
Long Island to Greenland. Off Block Island, 29 fathoms; Casco 
Bay, 10 to 20 fathoms; Bay of Fundy. Off Long Island, 37 fathoms, 
(Gould). Greenland, in 60 fathoms, (Mérch). 
ENSATELLA AMERICANA Verrill. Plate X XVI, fig. 182; Plate XXXII, 
fig. 245. (p. 356.) 
American Jour. Science, vol. iii, pp. 212, 224, 1872. Solen {mericanus Gould, Invert., 
ed. ii, p. 42, 1270 (provisional name). Solen ensis Gould, op. cit., ed. i, p. 23; 
and ed. ii, p. 40 (non Linné); Dekay, Nat. Hist. New York, Moll., p. 242, Plate 
33, fig. 313. Ensis Americana H. and A. Adams, Genera, vol ii, p. 342. 
Florida to Labrador. Common at Great Egg Harbor, New Jersey; 
Long Island Sound; Buzzard’s Bay; Vineyard Sound; Massachusetts 
Bay; Casco Bay; Bay of Fundy; Gulf of Saint Lawrence; low-water 
mark to 20 fathoms, sandy. Fort Macen, North Carolina, abundant, 
(Coues). Georgia(Couper). Wabrador, rare (Packard). Saint George's 
Bank (8S. I. Smith). 
Fossil in the Post-Plocene of Portland, Maine; Point Shiriey, Massa- 
chusetts; Nantucket; Virginia; and South Carolina; in the Pliocene 
of South Carolina; and Miocene of Maryland; North and South Caro- 
lina. 
In this species the siphonal tubes, in mature shells, protrude about 
35"™, and are united together for about half their length, beyond which 
they are round and divergent, subequal. Both orifices are surrounded 
by a similar circle of numerous papille, of three sizes ;, the larger ones 
are enlarged in the middle, acute at tips, with a large black spot on 
each side of the base; alternate with these are somewhat smaller ones 
-of the same form and with similar basal spots; alternating with the 
primary and secondary ones are small tapering papille, less than half 
the length of the longest; numerous slender tapering papille are also 
scattered irregularly over the sides of the free portions of both tubes, 
in some cases in irregular rows of four to six, while on the ventral side 
of the branchial tube two rows of alternating papille extend along the 
whole length of the siphon. The mantle is closed ventrally for most of 
its length; there is a posterior opening for the protrusion of the foot, 
and a small opening just in advance of it, and another opening near the 
middle of the ventral border; the latter is fringed with small conical 
papilla. Foot long; the end bulbous, obliquely truncated and beveled 
laterally. 
