NO. 2183. NEW NORTHWEST AMERICAN BIVALVES— DALE. 413 



anterior ribs are flattened; between the last six in the narrow inter- 

 spaces is a minute undulation which becomes obsolete as the shell 

 grows; the color of the shell is ivory white, more or less concentrically 

 mottled with reddish brown; interior white, channeled in harmony 

 with the radial sculpture, the margins, especially behind, deeply sul- 

 cate; beaks prominent, conspicuously incurved. Length, 43; height, 

 52; diameter, 36 mm. Cat. No. 193824, U.S.N.M. 

 Real Llejos, Gulf of Dulce, Central America. 



SAXIDOMUS GIGANTEUS Deshayes, 1839. 



New variety hrevis. Shell short, sub triangular, small in comparison 

 with type and much less elongated. Length, 60; height, 50; diam- 

 eter, 33 mm. Cat. No. 204020, U.S.N.M. 



Mole Harbor, Admu-alty Islands, Alaska, Mrs. Stephens. 



PROTOTHACA STAMINEA, new variety SPATIOSA. 



Shell large, heavy, rounded quadrate, inequilateral, the beak be- 

 hind the anterior end 18 mm.; yellowish or brownish wliite without 

 markings; sculpture of simple, similar, narrow radial ribs with nar- 

 rower interspaces, except on the posterior dorsal area where there 

 are a few wider ribs with deeper interspaces; inner margins finely 

 crenulate; pallial sinus deep, narrow, nearly horizontal. Length, 

 80; height, 67; diameter, 50 mm. Cat. No. 151562, U.S.N.M. 



Coos Bay, Oregon, Dall. 



PSEPHIDIA BRUNNEA, new species. 



Shell small, rounded triangular, moderately convex, brown, pale 

 yellow with zigzag brown reticulation, or even pale yellowish with 

 only traces of red or brown on the hingeline; surface apparently 

 smooth, with a dull silky effect, which on magnification is seen to be 

 due to minute concentric close-set threadlike sculpture; beaks promi- 

 nent, prodissoconch minute but distinct; hinge normal, strong; 

 inner margins entire, pallial sinus shallow, irregular. Length, 3.7; 

 height, 3; diameter, 2 mm. Cat. No. 109469, U.S.N.M. 



Catahna Island, CaUfornia, in 16 fathoms, Dall. 



The shells are often crowded with nepionic young as in Sphaerium. 



MACOMA BROTA, new name. 



This is TeUina edentula Broderip and Sowerby, 1829, not of Speng- 

 ler, 1793; and in part T. lata of Middendorff, 1851, not of Gmelin, 

 1792. 



The following form would seem to be specifically distinct were there 

 not a few intermediate specimens: 



