PSKUDODON IIOI 



Section Ocovai,is Simpson, 1900. 



Obovalis Simpson, Syn., 1900, p. 840. 



Shell obovate. subinflated, with a low, rounded posterior 

 ridge and with radiating wrinkles on the posterior slope; disk 

 nearly free from wrinkles ; epidermis blackish ; there is a high, 

 triangular tooth in each valve ; laterals very faint, rounded ; 

 nacre coppery. 



Type, Psciidodon loomisi Simpson. 



PsHUDODON LOOMISI Simpson. 



Shell slightly rhomboid, obovate, convex, scarcely subsolid, 

 inequilateral ; beaks moderately full, but little elevated ; pos- 

 terior ridge rounded, ending below the median line in a blunt 

 point ; dorsal border lightly arcuate ; basal line curved ; anter- 

 ior end rounded, subangular above ; dorsal slope obliquely sub- 

 truncate ; surface with irregular growth lines, which become 

 rather strong ridges in front, radiately plicate on the dorsal 

 slope ; epidermis nearly black, somewhat sericeous where not 

 worn ; left valve with one tooth and a vestigial one in front 

 of it ; right valve with a single tooth ; teeth elevated ; laterals 

 reduced to a rounded ridge ; anterior scars impressed ; posterior 

 scars shallow ; dorsal scars on the under side of the hinge 

 plate ; nacre bluish, becoming dull purplish in the cavities, 

 somewhat iridescent ; pallial line with a posterior sinus. 



Length 67, height 36, diam. 22 mm. 



Japan. 

 Pseudodon loomisi Simpson, Pr. Ac. N. Sci. Phila., 1900, p. 



84, pi. IV, fig. 7 ; Syn., 1900, p. 840. 



There is a single shell, the type, in the National Museum 

 collection. It differs from all other species of Pseudodon in 

 its obovate, elongated outline and radial plications on the dor- 

 sal slope. 



SPECIKS INCKRT.Ti SRDTS. 



Pseudodon soi.idus Haas. 



"Shell long-elliptical, solid, heavy, quite compressed, ante- 

 rior upper margin cui-ved, uniting without an angle the short, 

 steep anterior end, which curves gently into the slightly 



