download pdf

450 American Seashells
Genus Schizothaerus Conrad 1853
Shell large with a roundish posterior gape. Hinge with small cardinal
teeth; lateral teeth very small and close to the cardinals. Ligament external
and separated from the cartilage pit by a shelly plate.
Schizothaerus nuttalli nuttalli Conrad Pacific Gaper
Washington to Lower California.
Plate 31Z
Up to 8 inches in length. An oblongish to oval, strong, smoothish shell
with a prominent gape at the posterior end. The neat, well-formed beaks
are located M to % from the anterior end. The pallial sinus is very large
and deep. Periostracum grayish. Common. Compare with the northern sub-
species capax Conrad.
Schizothaerus nuttalli capax Gould Alaskan Gaper
Kodiak Island, Alaska, to Monterey, California.
Up to 10 inches in length, differing from the typical nuttalli in being
much more oval, more obese, and dipping downward into a well-rounded,
ventral margin. This species is very common on most sandy and mud beaches
in Puget Sound.
Genus Rangia Desmoulins 1832
Rangia cuneata Gray Common Rangia
Northwest Florida to Texas.
Figure 91a, b
I to 2% inches in length, obliquely ovate, very thick and heavy. The
beaks which are near the oval, anterior end are high, inrolled and pointing
downward and anteriorly. Exterior whitish, but covered with a strong,
smoothish, gray-brown periostracum. Interior glossy, white and with a bluegray
tinge. Pallial sinus small, but moderately deep and distinct. A common
fresh-water to brackish-water species found in coastal areas. R. iiasuta Dall
is probably only a rostrate form of this species. Compare with R. flexuosa.
Subgenus Rangianella Conrad 1867
Rangia flexuosa Conrad Brown Rangia
Louisiana to Texas and Vera Cruz, Mexico.
Figure 91c, d
I to 1% inches in length, rescmbUng an elongate cuneata, but with no