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232 American Seashells
I to i^ inches in length, slightly less than half as wide; strong, heavy
and pure white. Last whorl with about 13 small spiral cords and about 24
stronger axial ribs. Where they cross, there are small, rounded beads. Outer
lip near the low part has a shallow notch. Inside the lip are about a dozen
prominent, spiral ridges. Columella with 2 low spiral ridges near the base,
sometimes weaker ones above. Upper parietal wall with a strong spiral cord
running back into the aperture. Nuclear whorls smooth, glossy, white and
slightly carinate. Very commonly dredged from 20 to 100 fathoms.
Genus Engina Gray 1839
Engina turbinella Kiener White-spotted Engina
Plate 25W
Lower Florida Keys and the West Indies.
Vs to y2 inch in length, dark purple-brown with about 10 low, white
knobs per whorl on the periphery. Base with 2 to 4 spiral rows of much
smaller white knobs. Microscopic spiral threads numerous. Aperture thick-
ened and constricted by 4 to 5 whitish teeth on the outer lip and by a twist
of the columella just above the narrow siphonal canal. Do not confuse with
Mitra sulcata which has several columellar plications. Common under rocks
at low tide.
Genus Searlesia Harmer 191
Searlesia dira Reeve Dire Whelk
Alaska to Monterey, California.
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Figure 501!
I to I /4 inches in length, half as wide, with the brown aperture half the
length of the dark gray, fusiform shell. Outer lip thin but strong and with
fine serrations which extend back into the shell as small spiral threads. Colu-
mella arched, chocolate-brown and glossy. Whorls in spire with 9 to 1 1 low,
rounded axial ribs, and all of the exterior with numerous fine, unequal-sized
spiral threads. Siphonal canal short and slightly twisted to the left. A common
shallow-water species commonly from northern California to the north.
Genus Coluhraria Schumacher 18 17
Colubraria lanceolata Menke Arrow Dwarf Triton
North Carolina to both sides of Florida and the West Indies.
Plate 25X
% to I inch in length, slender, with 7 whorls. Aperture long and narrow.
Varix strong and curled back. Parietal shield elevated into a collar.