COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 65 



Pseudamussium (Peplum) fasciculatum (Hinds) 1845 



Plate 21 



Pecten fasciculatus Hinds, 1845, p. 61, pi. 17, fig. 4. "West coast of 



Veragua [Panama]. In seventeen fathoms, among sandy mud." 

 Pecten panamensis Dall, 1898, p. 696. No locality given, 

 [raow] Pecten (Pseudamusiuin) panamensis Dall, 1908, p. 404, pi. 6, 

 figs. 8, 10. ". . . Gulf of Panama . . . Acapuico, Mexico, to the 

 Galapagos Islands . . ." [= Cyclopecten (Delectopecten) zacae 

 (Hertlein) ; see that species, this paper.] 

 Pecten (Pallium) miser Dall, 1908, p. 401, pi. 8, fig. 6. "U.S.S. Alba- 

 tross, station 3355, Gulf of Panama, in 182 fathoms, mud, bottom 

 temperature 54° .1 F." 

 Pecten (Decadopecten) fasciculatus Hinds. Hertlein, 1935, p. 318, pi. 



18, figs. 1, 2. Panama. 

 Pecten (Mesopeplum) fasciculatus Hinds. Hertlein & Strong, 1946, p. 



59. Arena Bank, Gulf of California, to Panama. 

 Lyropecten (Peplum) fasciculatus (Hinds, 1845). Keen, 1958, p. 74, 

 fig. 138. 

 Holotype: Previously reported at British Museum, but not traceable 

 there at present (1958). 



Type locality : West coast of Veragua, Panama, in 17 fathoms. 

 Original description : Testa late subtrigona, planiuscula, tenui, in- 

 aequiauriculata, rufo-violascente albo maculata; valvis consimilibus, 

 costis parvis numerosis, eleganter serratis, in fascibus quinque plerumque 

 aggregatis, alteris interstitiis suppletis; auriculis inaequalibus, rectis, 

 argute serratis, dentatis ; intus violascente. 



Additional description: Shell rather small, maximum adult height 

 about 32 mm; slightly higher than long, usually somewhat oblique and 

 inequivalve, right valve exceeding left in convexity. Hinge line less than 

 half length of disk. Auricles unequal, anterior being longer; byssal notch 

 shallow and ctenolium of five teeth. Right valve moderately convex and 

 with ventral margin usually flexed; left flatter and flexed less sharply 

 or not at all. Ribs result of corrugations of disk; four in center of disk 

 prominent, rounded and becoming much wider at ventral margin ; a 

 narrower and lower rib next to anterior margin and two next to pos- 

 terior, with disposition occasionally reversed ; small radial ridges and 

 minute concentric lamellae covering disk. Anterior auricles with about 

 five imbricated radial ridges; posterior with one to three fairly strong 

 radial ridges adjoining hinge line, below them an excavated area having 



