PANAMIC-PACIFIC PELECYPODA 209 



spaced, and finer concentric striae. Hinge with two, strong, cardinal teeth 

 in each valve, the left anterior and the right posterior are double or bifid; 

 lateral teeth suppressed or with a tendency to become obsolete in the adult. 

 Principally deep water. 



Similar to Phaco'ides but has stronger, more widely spaced concentric 

 sculpture. The lateral teeth tend to become obsolete as the shell attains 

 maturity. 



Lucina (Lnclnoma) annulata Reeve Plate 30, figures 3-3b 



Lucina annulata Reeve, 1850, Conch. Icon., vol. 6, Lucina, pi. 4, fig. 17 "California". 

 Phaco'ides {Lucinoma) annulatus (Reeve), Dall, 1901, Proc. U.S. Nat. Museum, vol. 23, 



No. 1237, p. 824, pi. 40, fig. ID. 

 Lucinoma annulata (Re«ve), Woodring, 1938, U.S. Geol. Survey, Prof. Paper, No. 190, 



p. 53.— Woodring, Bramlette, and Kew, 1946, op. cit.. No. 207, p. 83.— Woodring 



and Bramlette, 1951, op. cit., No. 222, pp. 48, 65, pi. 19, fig. 8. 

 Lucinoma cf. L. acutilineata (Conrad), Woodring, Stewart, and Richards, op. cit., No. 



195, pi. 29, fig. 7. 

 Lucina {Lucinoma) annulata Reeve, Hertlein and Strong, 1949, Zoologica, vol. 31, pt. 



3, p. lis. 



Shell suborbicular, often large (height 55 mm.), the posterior-dorsal 

 side fairly long, straight, its margin not deeply sunken, white or chalky, 

 overlain by a brownish periostracum. Sculpture consists of fairly regular, 

 sharp, concentric lamellae spaced about 2 mm. or more apart, the flat 

 intervals between them with coarse, concentric threads. 



This is a northern species ranging southward into the Gulf of California. 

 Lucina (Lucinotna) chiripanica Olsson occurs plentifully in the Pliocene 

 of Charco Azul, Panama (Olsson, 1942, plate 4, figs. 1, 4), and possibly may 

 still be living in offshore waters. Another species of this group is L. 

 (Lucinoma) heroica Dall described from the coast of Mexico. 



Range — Alaska to the Gulf of California. 



Subgenus PLEUROLUCDfA Dall, 1901 

 Type species by original designation, Lucina leucocyma Dall. 



Shell small with a few large radial ribs crossed by coarse concentrics. 

 Hinge with cardinal and lateral teeth well developed. Lunule small, deeply 

 impressed, and overhung by the coiled beaks. 



Lucina (Pleurolucina) uodatoides Hertlein and Strong Plate 31, figure 13 



Lucina undata Carpenter, 1865, Proc. Zool. Soc. London, p. 279 "Gulf of California". — 



Carpenter, 1872, reprinted in Smith. Misc. Coll., No. 252, p. 272. (Not Lucina 



undata Lamarck, 1819). 

 Phacoides (Pleurolucina) undatus (Carpenter), Dall, 1901, Proc. U. S. Nat. Museum, 



vol. 23, No. 1237, pp. 811, 826, pi. 39, fig. 14. 

 Lucina undatoides Hertlein and Strong, 1945, Nautilus, vol. 58, p. 105. (New name for 



L. undata Carpenter, not Lamarck, 1819). — Hertlein and Strong, 1946, Zoologica, 



vol. 31, pt. 3, p. 117. 



Shell small (length 11 to 12 mm.), rounded, moderately convex, white. 

 Dorsal areas well defined, deeply impressed, the posterior one the larger. 

 Sculpture produced by four, large, somewhat fan-shaped radial ribs be- 

 tween narrower interspaces, the entire surface crossed by coarse, even con- 

 centrics. 



Range — Gulf of California. 



