PANAMIC-PACIFIC PELECYPODA 167 



Dall, 1909, Proc. U. S. Nat. Museum, vol. 37, No. 1704, p. 256.— Zetek, 1918, 

 Los Moll. Republ. Panama. Revista Nueva. Probably Panama. Not P. digiiatum 

 Perry, 1811, Conch., No. 2, in expl. to pi. 55, fig. 2 (Amboyna and Eastern 

 Seas). 

 Pecten (Chlamys) zeteki Hertlein, 1935, Proc. California Acad. Sci., ser. 4, vol. 21, No. 

 25, p. 306, pi. 19, fig. 9. 



Shell somewhat triangular, rather flat, solid, equal-eared, pale, clouded 

 transversely with blood-red; valves very like, with some rounded, grooved 

 ribs; umbones rather flat, smooth; margins minutely denticulated; white 

 within. Reeve after Hinds. 



Additional specimens of this small Pecten have apparently not been 

 found since its original discovery. Dall suggested that it could well be a 

 young P. subnodosus. The species will remain questionable until new material 

 becomes available or the type (if still extant) can be reexamined.* 



Gulf of Guayaquil (Hinds). 



Subgenus FLEXOPECTEN Sacco, 1897 

 Type species by original designation, F. jlexuosus (Poli). Mediterranean. 



Relatively small shells, the sculpture of the valves similar and formed 

 by a few, wide ribs as if the surface had been sharply folded or creased 

 along radial lines. 



Chlamys (Flexopeeten) fascienlata (Hinds) Plate 20, figures 2-2b 



Pecten fasciculatus Hinds, 1845, Zool. Voy. Sulphur, Moll. Pt. 3, p. 61, pi. 17, fig. 4 



"West coast of Veragua. In seventeen fathoms, among sandy mud." 

 Pecten {Pallium) miser Dall, 1908, Bull. Mus. Comp. Zool., vol. 43, No. 6, p. 401, pi. 8, 



fig. 6 "Gulf of Panama in 182 fathoms." 

 Pecten (Decadopecten) fasciculatus Hinds, Hertlein, 1935, Proc. California Acad. Sci., 



ser. 4, vol. 21, No. 25, p. 318, pi. 18, figs. 1, 2. 

 Pecten (Mesopeplum) fasciculatus Hinds, Hertlein and Strong, 1946, Zoologica, vol. 



31, pt. 2, p. 59. 



Shell small or of medium size, slightly inequilateral and equivalve, 

 high and narrow above, the ears small, and the hinge line short, the general 

 surface of each valve flattish but with the basal margin contracted sharply 

 in the adult so that the edges meet each other nearly vertical. Shell texture 

 is rather thin, its surface folded so as to form five or six heavy ribs (more 

 or less similar in each valve) of which the middle three are the largest; in 

 addition, the whole surface is covered with small radial threads or cords; 

 in the left valve, the radial threads are wider than their interspaces, the 

 latter crossed by upward looped concentric threads producing a network of 

 rectangular or hexagonal cells; on the right valve, the secondary riblets are 

 larger, rounder, and are separated merely by pitted grooved lines. The ribs 

 are absent from the turned down marginal zone, the only sculpture there 

 is the cordlike radials. In the interior, because of the thinness of the shell, 

 the ribs and interspaces are shown in the reverse, the edges of the ribs by 

 a thickened cord. Ears small, the anterior one a little longer. Hinge line 

 without crura. Color in the specimens seen is a mauve or dull raspberry 

 red, clouded with blotches of yellow or cream. 



Length 29.1 mm., height 31 mm., semidiameter 9 mm. right valve. 



*Gilbert Grau's long awaited work appeared while this paper was in press: 

 Pectinidae of the eastern Pacific (Allan Hancock Pacific Expeditions, vol. 23). Accord- 

 ing to Grau, the Pecten digitatus of Hinds is probably a juvenile specimen of SetnipalHum 

 vexillum (Reeve), an Indo-Pacific species. He concluded that it is almost certain that 

 the original specimen of P. digitatus was collected in the western Pacific during the 

 voyage of the Samarang and not as stated in the Gulf of Guayaquil. 



