52 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



an altitude of from 10 to 14 mm. The valves seldom have similar sculp- 

 ture, usually only one having pronounced radial threads. 



Remarks'. Dall first used the name Pecten pana?nensis in 1898 {loc 

 cit.). In discussing the "section" Pallium he said, "Pecten panamensis 

 Dall, which has in most respects an unusually close resemblance to P. 

 plica, differs in having the cardinal laminae obsolete and in the presence 

 of a byssal sinus and ctenolium." Discussing genera, he said, "Bucquoy, 

 Dautzenberg, and Dollfus (1889) propose Peplum, with P. clavatus 

 Poli as type, which would include such species as P. panartiensis.^^ No 

 further description (in the accepted sense of the word) was given, nor 

 was the species figured, but the features he mentioned in the first sen- 

 tence, those he implied in the second, and the locality inferred by the 

 name, add up to what may be construed as a "definition," in accordance 

 with Article 25 of the International Rules; thus Pecten panamensis 

 (1898) was established as a published name. Hinds, however, had 

 described the same species in 1845 as Pecten fasciculatus (see Pseud- 

 amussium (Peplum) fasciculaturn (Hinds), this paper); of that there 

 can be no doubt, for no other species of Peplum is found in the eastern 

 Pacific. Therefore, Dall's Pecten panamensis (1898) was a synonym for 

 P. fasciculatus Hinds from the time it was published. Apparently for- 

 getting that he had previously named the species, Dall described and 

 figured it in 1908 as Pecten (Pallium) miser, thus adding another syn- 

 onym for P. fasciculatus. In the same 1908 paper Dall described and 

 figured Pecten (Pseudamusium) panamensis; since that name had been 

 published earlier, P. panamensis (1908) was a homonym, and Hertlein 

 rectified the matter in 1935 by re-naming the species Pecten (Delecto- 

 pecten) zacae. 



Geographical range: Punta San Fermin, northern Gulf of Cali- 

 fornia, to Panama Bay. Also Galapagos Islands. The author determined 

 the Clipperton Islands specimens referred to this species to be Cyclo- 

 pecten (Delectopecten) vitreus (Gmelin). The previously recorded 

 northern limit for C. zacae was San Jose del Cabo, eastern Lower Cali- 

 fornia (Hertlein, 1935, p. 321), but in July, 1958, Dr. H. A. Rehder, 

 of the U. S. National Museum, sent the author 139 lots of eastern 

 Pacific material from the Museum collection for identification, and one 

 lot contained a specimen from Albatross station 3035, off Punta San 

 Fermin; that record extends the northern range by about 570 miles. 



Geochronological range: Recorded only from the Recent. 



Bathyfnetric range: Recorded in 5 to 1005 fathoms. 



Ecological data : Found only on mud bottoms. 



