PANAMIC-PACIFIC PELECYPODA 213 



if Still extant, could settle the question permanently. It is the Pacific 

 analogue of L. muricata Spengler of the West Atlantic. 



Range — Gulf of California to northern Peru. Panama: San Carlos; 

 Bucaro. Colombia: Isla del Gallo. Ecuador: Santa Elena; Galeras; 

 Mompiche. Peru: Tumbez; Zorritos; Boca Pan; Mancora. 



Lncina (Lucinisca) fcuestrata Hinds Plate 29, figure 10 



Luclna fenestrata Hinds, 1845, Zool. Voy. Sulphur, Moll. pt. 3, p. 66, pi. 19, fig. 2 



Monte CliristI ; San Bias. 

 Lucina (Lucinisca) fenestrata Hinds, Dall, 1901, Proc. U. S. Nat. Museum, vol. 23, 



No. 1237, p. 811.— Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 3, pp. 113, 



114.— Hertlein and Strong, 1955, Bull. Am. Mus. Nat. Hist, vol. 107, art. 



2, p. 183, pi. 1, fig. 7. 



Shell large (length 55 mm.), subcircular to suborbicular, equivalve and 

 of slight or moderate convexity, white. Beaks small, pointed, placed a little 

 in front of the middle. Dorsal areas impressed and sharply differentiated 

 from the rest of the disk, the posterior area much larger, its margin wide 

 and somewhat obliquely truncated. Surface sculpture is fine and uniform, 

 produced by a series of small, slightly waved, radial riblets intersected by 

 concentrics and producing a fine, sharp cancellation. The sculpture of the 

 posterior-dorsal area is similar, except that the radials are more irregularly 

 distributed. Anterior-dorsal area is much smaller and generally divided into 

 two unequally sculptured portions. The basal margin is obliquely rounded, 

 finely crenulate within. Lunule small. 



Length 51 mm., height 44.8 mm., diameter 17.8 mm. 



Length 55 mm., height 49.1 mm., diameter 17.7 mm. 



This is the largest and finest species of the subgenus, and characterized 

 by its fine, uniform sculpture. Formerly rare in most collections, the species 

 appears to be fairly plentiful in offshore waters of from 10 to 30 fathoms 

 depth and is now obtained by shrimp trawlers in fair numbers. L. fausta 

 Pilsbry and Olsson from the Pliocene of Ecuador is closely related. 



The identification of this large Lucinisca with fenestrata is not entirely 

 certain; the figure of that species given by Hinds in the Voyage of the 

 Sulphur shows a small, more circular shell with coarse, irregular sculpture, 

 some of the radial costae split or divided as they approach the ventral 

 margin. In the large number of specimens examined, none agree exactly 

 with the original figure. 



Range — Gulf of California to Panama and Ecuador. Panama: off 

 Panama (shrimpers). Colombia: Ardita Bay (Hertlein and Strong). 



Subgenus PARYn.UCINA Dall, 1901 



Type species by original designation, Lucina tenuisculpta Carpenter. 



Shell small, rounded, plump, inequilateral. Surface smooth or sculp- 

 tured with small radial and concentrics, generally forming a weakly or 

 finely cancellate pattern. Dorsal areas not defined or obscure. Hinge teeth 

 typically small but all present. Ventral margins crenulated. 



