PANAMIC-PACIFIC PELECYPODA 35$ 



grooved or bifid central cardinal tooth with a socket on each side, also a 

 small thin posterior cardinal tooth; right valve has two strong cardinal teeth 

 and a central socket; lateral teeth are partly obsolete, the right valve has 

 a small anterior and posterior tooth. Surface marked with concentric growth 

 lines. Pallial sinus is large, rounded, and extends to about the middle of 

 the shell cavity. Valve margins plain. 



Heterodonax bimaculatos (Linn6) Plate 85, figure 10 



Tellina bimaculata Linnc, 1758, Syst. Nat, ed. 10, p. 677. — Hanley, 1846, Thes. Conch., 



vol. 1, Tellina, p. 250, No. 52, pi. 56, figs. 16, 19, 20, 21, 22.— Sowerby, 1866, 



Conch. Icon., vol. 17, Tellina, pi. 18, figs. 94a, b, c. 

 Psammobia pacifica Conrad, 1837, Jour. Acad, Nat. Sci. Philadelphia, vol. 7, p. 241, 



pi. 18, fig. 13. 

 Tellina vicina C. B. Adams, 1852, Ann. Lyceum Nat. Hist. New York, vol. 5, pp. 509, 



546, No. 473. — Turner, 1956, Occas. Papers on Mollusks, Mus. Comp. Zool., 



vol. 2, No. 20, p. 98, pi. 18, figs. 11, 12. 

 Donax ovalina Deshayes, 1855, Proc. Zool. Soc. London for 1854, p. 352. 

 Donax ovalinus Deshayes, Sowerby, 1866, Thes. Conch., vol. 3, Donax, p. 312, No. 47, 



pi. 283, fig. 104. 

 Heterodonax bimaculata (Linne), Hertlein and Strong, 1950, Zoologica, vol. 35, pt. 



4, p. 221. 



Shell triangularly rounded to ovate, with the beaks nearer the pos- 

 terior end which generally appears somewhat truncated. Surface sculptured 

 with coarse irregular concentrics and often showing short irregular radial 

 lines or streaks. Color variable from white, salmon, brown, violet to purple, 

 often rayed or maculated. Average size about 22 mm. 



This species is also found in the Western Atlantic. Generally variable 

 in surface color and markings. 



Range — Southern California to northern Peru. Panama: Pedro Gon- 

 salez. Pearl Islands. Panama Canal Zone: Venado beach; Farfan. Peru: 

 Tumbez (Weyrauch). 



Genus GABI Schumacher. 1817 

 {Psammobia Lamarck, 1818.) 

 Type species by tautonomy, G. vulgaris Schumacher (=Tellina gari 

 Linne). 



Shell slantingly elongate-ovate or subrectangular, with the beaks and 

 umbones placed submedian or slightly nearer the posterior side. The two 

 ends more or less rounded, equivalve, depressed or slightly convex, thin or 

 of medium weight. Nymphal plate prominent. Hinge with one or two 

 cardinal teeth in each valve, one or both of which may become partly obso- 

 lete. Pallial sinus large, its upper margin straight, end widely rounded, its 

 lower margin confluent with the pallial line. Adductor scars placed high 

 within the valve or just below the dorsal margin. Periostracum usually coarse 

 and heavy; beneath it the surface is usually mottled or rayed with purple, 

 smooth, or with growth line striation only. 



Two subgenera. 



L Posterior end of the valves somewhat pointed; closed or with a small 

 gap only. 



Subgenus Gan, s.s. 

 IL Posterior margin of valves evenly rounded or truncated, the end widely 

 open. 



Subgenus Gobraeus 



