PANAMIC-PACIFIC PELECYPODA 217 



In the Panama specimen, the ribs are sharply defined over the whole 

 surface while in most of the Indo-Pacific specimens I have examined, they 

 are generally obsolete across the middle; in the Galapagos specimen (a left 

 valve), the sculpture is intermediate, the ribs are partly obsolete in the 

 middle. 



Length 62.8 mm., height 57.8 mm., diameter 27.1 mm. Panama. Swift 

 coll. ANSP 54393. 



Range — Panama southward to the Galapagos Islands. Indo-Pacific. 

 Panama: Panama (ANSP). 



Codakia (Codakia) dlstinqnenda (Tryon) Plate 29, figure 3; 



Plate 33, figures 4, 4a 



Lucina (Codakia) distinquenda Tryon, 1872, Proc. Acad. Nat. Sci. Philadelphia, vol. 



24, p. 130, pi. 6, fig. 3 Gulf of California. 

 Codakia colpoica Dall, 1901, Proc. U. S. Nat. Museum., vol. 23, No. 1237, pp. 801, 821, 



pi. 41, fig. 4 Gulf of California 

 Codakia distinquenda Tryon, Maxwell Snnith, 1944, Panamic Marine Shells, p. 57, fig. 



729.— Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 3, No. 8, pp. 117, 118. 



Shell large, circular or orbicular, generally heavy and thick. Sculpture 

 formed by small, finely beaded or cancellated, radial riblets, a few of the 

 riblets are occasionally larger and separated by deeper radial grooves giv- 

 ing the effect of wide rays. Hinge plate much wider or higher than in the 

 West Indian or Caribbean C. orbicularis; the hinge plate and internal mar- 

 gins of the valves are usually colored a deep, rose-purple. 



Length 76 mm., height 68 mm., diameter 22 mm. (Dall) 

 Length 74.6 mm., height 68.7 mm., diameter 10 mm. (left valve, Isla 

 la Plata.) 



According to Hertlein and Strong, this species is fairly common in the 

 Gulf of California. It is rare elsewhere. A large specimen from the Gulf of 

 California recorded by Hertlein and Strong measures 140 mm. in length. 

 It occurs rarely as a Pleistocene fossil in the Tablazos of Ecuador; a speci- 

 men from near the oil pits of Cautivo on the Santa Elena Peninsula has a 

 length of about 115 mm; this specimen is heavy with wide radial riblets 

 and resembles the figure of Codakia recta Dall and Ochsner, described as 

 a Pliocene fossil from the Galapagos. 



Range — Lower California to Ecuador. Ecuador: Isla la Plata. 



Codakia (Codakia) pinchoti Pilsbry and Lowe 



Codakia pinchoti Pilsbry and Lowe, 1932, Proc. Acad. Nat. Sci. Philadelphia, vol. 84, 

 p. 103, pi. 14, figs. 1, 2. — Maxwell Smith, 1946, Panamic Marine Shells, p. 

 57, fig. 723. 



Like C. orbicularis of the West Indies but slightly more ventricose (the 

 diameter about half the length), the lunule shorter and deeper. Exterior 

 white, the concentric sculpture less sharp than in C. orbicularis; at irregular 

 intervals growth rests are rather conspicuous. Interior not punctate though 

 sometimes somewhat roughened, white, with a coral-oink submargin, 

 broadening and becoming deep madder at the dorsal margin. 



