COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 3 



Since this paper had its inception in a study of the Hancock Pacific 

 expeditions material, it concerns the fifty-four species of Pectinidae 

 known to be living in the eastern Pacific, seven of which were previously 

 unknown and are described herein. Because of synonyms involved it was 

 also necessary to include two species definitely extra-limital and one 

 almost certainly so. The first two are Cyclopecten (Delectopecten) 

 greenlandicus (Sowerby) and Pecten ( ?var.) squarrosus Carpenter; 

 the third is Semipallium zeteki (Hertlein). 



As used in this paper, the term eastern Pacific refers to the coastal 

 waters of North and South America, limited on the north by Bering 

 Strait, on the south by the Strait of Magellan, and along most of its 

 western boundary by the Eastern Pacific Barrier of Ekman (1935, p. 

 105; 1953, p. 72. Also Sverdrup, Johnson & Fleming, 1942, pp. 803, 

 860-861, fig. 220). The Barrier, ". . . the pelagic and abyssal region 

 between outermost Poljmesia and America . . ." (Ekman, 1953, p. 72), 

 has effectively prevented migration of all but a few marine animals. A 

 line drawn from Easter Island to the Hawaiian Islands indicates the 

 approximate eastern limit of the Polynesian region. A line drawn from 

 60° south and 80° west to Clipperton Island, from there to the central 

 Aleutian Islands and then to Bering Strait, indicates the approximate 

 western boundary of the eastern Pacific. 



This paper is a revision of the genera and species of Pectinidae 

 native to the eastern Pacific and a report on the material of that family 

 resulting from the Hancock Pacific expeditions. The study material used 

 in its preparation consisted of the Hancock Foundation collection (con- 

 taining twenty-six of the forty-eight previously described species and 

 seven new species), the eastern Pacific portion of the author's collection 

 (containing forty-one of the previously described species and including 

 paratypes of twelve species), the Los Angeles County Museum collec- 

 tion, and type-lot specimens borrowed from the U.S. National Museum 

 and the National Museum of Canada. Specimens of some species were 

 also examined in the collections of the California Academy of Sciences 

 (San Francisco), Stanford University and the San Diego Museum of 

 Natural History. 



Undoubtedly some persons will disagree with certain of the author's 

 conclusions. Contemporary systematics being a field too large in scope 

 for thorough discussion here, he can only claim to have relied on care- 

 fully considered judgment in reaching those conclusions. From the 

 semantic standpoint many of the taxonomic categories we employ are 

 actually philosophical concepts, are subject to interpretation on the basis 



