PANAMIC-PACTFIC PELECYPODA 407 



Often found in association with M. virgo, and as indicated above, easily 

 recognized by its much finer sculpture. 



Range — Mexico to northern Peru. Panama: Biicaro. Peru: Tumbez; 

 Boca Pan. 



Moerella (Scissnla) esmeralda, new species Plate 68. figure 11; 



Plate 72, figure 5 



Shell nearly 20 mm. in length, ovately elongate, inequilateral, nearly 

 equivalve, the ventral side longer, straight and nearly parallel to the much 

 shorter, central-dorsal margin, flatly compressed, thin, white to subtrans- 

 lucent. The beak is placed near the posterior one-third, hence, the posterior 

 side is shorter, its marginal end straight to slightly subtruncated, the longer 

 anterior side widely rounded at the end. The surface is sculptured on the 

 anterior two-thirds of the disk by finely incised, oblique lines which end 

 sharply in front of the posterior umbonal slope; behind this zone, the surface 

 is mainly smooth. Posterior-umbonal angle is low, almost flat. Substance 

 of shell thin and glassy, the surface sculpture showing as plainly on the 

 inside as on the outside. Submicroscopic streaks and larger rays may show 

 on some specimens. 



Length 19.7 mm., height 10.3 mm., diameter 3.1 mm. (type) 

 Length 23.2 mm., height 12.2 mm., diameter 2.2 mm. (a right valve). 



Camarones, Ecuador. Holotype, ANSP 218946. 



Range — Ecuador. Ecuador: Camerones (beach). 



Genus ELPIDOLLINA, new genus 

 Type species, Tellina decumbens Carpenter. Recent, Panama. 



Shell with thin, subtrigonal valves, thin and rather inflated, subequal, 

 the posterior side shorter and pointed, and hardly flexed. The hinge pro- 

 vided with both cardinal and lateral teeth, the cardinals usually small and 

 of which the left anterior and the right posterior teeth are bifid, the others 

 much smaller and simple. The lateral teeth are fairly large in the right 

 valve, much smaller in the left; the anterior lateral tooth is placed near 

 but not actually in contact with the cardinal tooth, the posterior lateral 

 tooth more distant and beyond the end of the ligament scar. The ligament 

 is external, its scar long and narrow. The pallial sinus is large and deep, 

 highest under the beak and extending across to connect with the anterior 

 adductor scar; its lower limb is fully confluent with the paUial line. Surface 

 smooth except for minute lines of growth. 



Elpidollina decnmbens (Carpenter) Plate 68, fgures 14, 15 



Angulus amplectans Carpenter, 1863, Rept. British Assoc. Adv. Sci., p. 669 nude name. 

 (.Tellina) Angulus decumbens Carpenter, 1865, Proc. Zool. Soc. London, pp. 278, 279. 



Reprinted 1872, Smitii. Misc. Coll., No. 252, pp. 271, 272 Panama. 

 Tellina peasii Sowebry, 1868, Concli. Icon., vol. 17, Tellina, pi. 49, fig. 288. 

 Tellina (Moerella) decumbens (Carpenter), Myra Keen, 1958, Sea Shells of Tropical 



West America, p. 170, fig. 395. 



