CARDIIDAE 399 



I to 2 inches in size, squarish in outline, thick, inflated, with 33 to 36 

 strong radial ribs which are covered with close-set, chevron-shaped plates. 

 External color whitish with mottlings of reddish brown. Interior usually 

 white, or may be flushed with orange, rose-brown or purple. The posterior 

 slope is pushed in somewhat and is slightly concave. A relatively common 

 species found in shallow to moderately deep water. 



The Western Strawberry Cockle, T. biangiilata Sowerby, is the Cali- 

 fornian counterpart of the above species. It is iVi inches in length, with 

 about 30 strong ribs; exterior yellowish white, interior reddish purple. 

 Moderately common. 



Subjavnly PROTOCARDIINAE 

 Genus Nemocardium Meek 1876 



Nemocardhnn centifilomin Carpenter Hundred-lined Cockle 



Alaska to Lower California. 



% to % inch in length, almost circular; posterior third of shell with 

 cancellate sculpturing and separated from the finely ribbed anterior two 

 thirds of the shell by a single raised rib. Edge minutely serrate. Exterior 

 with gray, greenish gray or brownish gray, thin, fuzzy periostracum. In- 

 terior dull- white. Fairly common. 



Genus Microcardiwn Thiele 1934 



Microcardiwn peramabile Dall Eastern Micro-cockle 



Rhode Island to southeast Florida and the West Indies. 



% to % inch in length, thin, inflated, subquadrate, white, but may be 

 mottled tan on the anterior slope. Sculpture prominent on the posterior 

 third of the valve. It consists of about 90 closely packed, radial ribs (spinose 

 posteriorly) which are crossed by minute concentric threads. The anterior 

 two thirds is separated from the rest of the shell by a single, crested, spinose, 

 radial rib. Very commonly dredged off eastern Florida. 



Microcardium tinctu?n Dall, found with the above species, is % inch 

 in length, stained with rose-red and has more than 150 minute, radial ribs. 

 Uncommon. 



Siibjainily LAEVICARDIINAE 

 Genus Laevicardimn Swainson 1840 



Laevicardium laevigatum Linne Common Egg Cockle 



Plate 39k 



North Carolina to both sides of Florida and the West Indies. 



