COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 9 



12. Hinge line very short, % to 5^ 

 length of disk; orbicular or nearly; 

 ventral margins often sharply com- 

 pressed ; 5-11 ribs .... 



Subgenus Peplum 



1. Only right valve convex; left valve flat or nearly 



13. Right valve moderately convex; left valve flat, concave or 



slightly convex Genus Pecten 



13. Right valve deeply convex and umbo strongly inflated; left 

 valve convex .... Subgenus O ppenheimopecten 



Genus PROPEAMUSSIUM de Gregorio 1884 



Propeamussium de Gregorio, 1884a, p. 119. [Proposed as a subgenus 

 of Pecten.\ Type species: Pecten (Propeamussium) ceciliae de 

 Gregorio, 1884a, p. 119; type locality: Miocene of Terrebianche, 

 Sicily.— de Gregorio, 1898, pp. 5, 19, pi. 4, figs. 10-14. 



Propeamusium de Gregorio (em.), 1883. Dall, 1886, p. 210. [Dall's 

 emendation of Propeamussium invalid; date incorrect: de Gre- 

 gorio's diagnosis written in 1883 but published in 1884. Pecten 

 fenestratus Forbes (1844, p. 192) designated as type species; that 

 species herein referred to Parvamussium.] 



Paramusium Verrill, 1897, p. 72. Type and only species: Amussium dalli 

 E. A. Smith, 1885, p. 308, pi. 22, figs. 7, 7a-c [referred to Vari- 

 amussium by Cossmann & Peyrot, 1914, p. 105] ; type locality: 

 Challenger station 33, ofif Bermuda, in 435 fathoms. 



Pseudopalliorum Oyama, 1944, p. 244. [Error for Pseudopalliolum; 

 proposed as a subgenus of Propeamussium.^ Type species: Pecten 

 interradiatus Gabb, 1869, p. 199, pi. 33, figs. 98, 98a; type locality: 

 east of New Idria, San Bernardino County, California (Eocene). 



Flavamussium Oyama, 1951, p. 81. [Proposed as a subgenus of Parv- 

 amussium.] Type species: Amussium caducum E. A. Smith, 1885, 

 p. 309, pi. 23, figs. 1, la-lc; type locality: Challenger station 207, 

 west of Luzon, Philippine Islands, in 700 fathoms. 



Luteamussium Oyama, 1951, p. 82. Type species: Amussium Sibogai 

 Dautzenberg & Bavay, 1904, p. 207, text-figs. 1-4; type locality: 

 Challenger station 12, Celebes Sea, in 289 meters. 

 Original diagnosis (and description of tj^pe species) : Conchiglia 



estremamente tenue e compressa; con superficie interna ed esterna levi- 



gata. ... La scultura consiste in filetti lineari sottilissimi, concentrici, 



e raggianti; nella regione perif erica sono essi quasi del tutto cancellati, 



