COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 123 



P. digitatum Perry. [Not listed by Zetek, as Hertlein said, among 

 species probably occurring in Panama.] 



Holotype: British Museum? 



Type locality : Guayaquil, Ecuador. 



Original description : Testa subtrigona, planiuscula, solida, aequi-" 

 auriculata, pallida, sanguineo transversim nubeculata ; valvis consimili- 

 bus, costis novem rotundatis sulcatis ; auriculis sulcatis ; umbonibus 

 subplanulatis, laevigatis; marginibus minute denticulatis; intiis alba. 



Remarks: No species even remotely resembling Hinds' Pecten digita- 

 tus has ever been found in the eastern Pacific. In vievi^ of the known 

 confusion as to the actual localities of a number of his species (see 

 Remarks under Chlamys hastata, this paper), we can be almost certain 

 that the holotype of Pecten digitatus was collected in the western Pacific 

 during the voyage of the Samarang, and is actually a juvenile specimen 

 of Semipnllium vexillu?n (Reeve). 



Perry's stylized and peculiarly colored figure is rather anomalous; 

 if his holotype were located and found to be identical with Reeve's shell, 

 Pecten digitatum Perry would have priority. 



Subgenus JUXTAMUSIUM Iredale 1939 



Juxtamusium Iredale, 1939, p. 368. [Proposed as a genus.] Type species: 

 Pecten tnaldivensis E. A. Smith, 1906, p. 622, pi. 36, figs. 19-20 

 [= Juxtamusiu?n oblectatum Iredale, 1939, p. 368, pi. 5, figs. 27- 

 27a, designated type species by Iredale; type locality: Half mile W 

 of North Direction Isle, Great Barrier Reef, 20 fathoms] ; type 

 locality: Maldive Islands. 

 Original diagnosis (of Juxtamusium oblectatum; none given for 

 the genus) : Shell subcircular, thin, compressed, equivalve, almost equi- 

 lateral, gaping a little at the sides, ears large, unequal. 



The surface is finely striate radially on the right valve, which is 

 coloured, but completely overridden by very fine, closely-set, concentric 

 striae; the left valve is uniformly pale and the radials are practically 

 obsolete, while the concentric striae are microscopic. Internally the edge 

 is closely ribbed, but the ribs do not extend far into the valve. Hinge 

 folded, but striae missing, the ligamental groove triangular, but the 

 ligament itself linear. The type from Station XVI measures 22.5 mm. 

 in height and 22 mm. in breadth, the depth of the conjoined valves 

 being only 6 mm. 



