Long. 0·42, lat. 0·28, alt. 0·16.
Hab. San Diego, San Pedro, 50, alive, at low water.
Genus Plectodon.[16] Cpr.
Testa tenuis, scaber, rostrata, haud inflata: margo dorsalis sub umbones intus nexa, dentem cardinalem formans: dentes laterales longi, laminati: cartilago fossâ minutâ, sub umbones celatâ, dente laterali postico contiguâ, sita: sinus pallii parvus.
Plectodon scaber, Cpr. n. s. State Collection, No. 1062.
Pl. t. ledæ-formi, tenui, subdiaphanâ, pallidâ; totâ superficie minute pustulosâ; marginibus dorsalibus rectis, ad angulum 150°; antice et ventraliter productâ, marginibus excurvatis; postice valde rostratâ, truncatâ: intus, margine sub umbones interrupto; plicâ ex apice oblique usque ad marginem dorsalem anticum excurrente; dentibus lateralibus laminatis, extantibus, postico longiore; cicatricibus adductoribus parvis, subrotundatis, ad extremitates dentium lateralium sitis; sinu palii lato, haud impresso.
Long. 0·62, lat. 0·34, alt. 0·20.
Hab. Catalina Island, two right valves, 40-60 fms, Cp.
This very distinct genus has the aspect of Theora, and appears allied to Neæra. It is probable that the cartilage was strengthened by an ossicle. The great peculiarity is the twisting-in of the dorsal margin, which ascends the umbo in a very loose spiral.