440 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50- 



posterior, turned slightly forward, and somewhat prominent. Ante- 

 rior margin slightly depressed in front of beaks, but convex below 

 this ; anterior angle somewhat more sharply rounded than posterior, 

 giving the valve an obliquely protruding appearance anteriorly. 

 Posterior margin and base regularly rounded. The sculpture con- 

 sists of 8 or 9 broad falcate ribs separated by narrow incised inter- 

 spaces and several (8 in the type) very prominent concentric 

 imbrications of growth ; in addition to the latter are numerous fine 

 incremental lines. Hinge relatively narrow for one of this genus. 



Dimensions. — Altitude, 4 mm. ; latitude, 4 mm. ; diameter of sin- 

 gle valve, 1 mm. 



Notes.- — This species is more closely related to V. incisa Dall than 

 to any of the other West Coast forms, but is easily distinguishable 

 from the latter by the fewer number (8 in type of yatesi, 19 in type of 

 i w ma) and greater breadth of its ribs, relatively smaller size and 

 shorter and more angulated outline anteriorly. Named in honor of 

 Dr. Lorenzo G. Yates, Santa Barbara, California. 



Type.— Cat. No. 165,248, U. S. N. M. 



Locality. — Bath-house Beach, Santa Barbara, California. (Delos 

 and Ralph Arnold.) 



Horizon. — Fernando formation (Pliocene or lower Pleistocene). 



PSEPHIDIA BARBARENSIS, new species 

 PL LVIII, fig. 3 



Description. — Shell averaging about 4 millimeters in altitude; 

 subtrigonal in outline, ventricose. Beaks slightly anterior of the 

 center, bowed slightly forward, but not prominent. Anterior mar- 

 gin nearly straight ; anterior angle broadly rounded ; base not prom- 

 inently rounded ; posterior angle much sharper than anterior ;. 

 posterior margin regularly bowed and much more rounded than 

 anterior. Surface smooth except for very fine lines of growth. 

 Muscle scars prominent ; pallial sinus oblique and extending nearly 

 to middle of valve. The hinge consists of three prominent teeth — ■ 

 the middle one heavy, triangular, and slightly sulcated, the anterior 

 and posterior ones short. 



Dimensions. — Altitude, 4 mm.; longitude, 4.1 mm.; diameter of 

 single valve, 1 mm. 



Notes. — This species is higher and more trigonal in outline, has 

 a straighter anterior margin, and a less conspicuous anterior tooth 

 than P. lordii Baird, which it resembles. Named for the type local- 

 ity, Santa Barbara. 



Type.— Cat. No. 165,238, U. S. N. M. 



