PANAMIC-PACIFIC PELECYPODA 381 



Genus TELIEDORA H. and A. Adams, 1858 



Type species by original designation, Dall, 1900. Tellina burneti Brod- 

 erip and Sowerby. Panamic-Pacific region. 



Shell of medium size, triangular, with high, central beaks and nearly 

 equal sides, the dorsal margins commonly crested or serrated. The valves 

 have unequal inflation, one or the other, according to species, being depressed 

 or flattened, the other mildly convex. Ligament partly immersed, the 

 tensilium attached to a long, deep groove, the resilium to a smaller scar 

 below it. The hinge has two, small cardinal teeth in each valve, the anterior 

 left and the posterior right cardinal teeth are bifid, the other much smaller, 

 narrow and sometimes partly obsolete. The pallial sinus is deep and half 

 confluent below. Surface smooth pr with concentric undulations on the 

 umbones. 



There are two Recent species, T. cristata Recluz, found in Atlantic- 

 Caribbean waters, and T. burneti Broderip and Sowerby in the Pacific zone. 

 They differ from each other in the reversed convexity of their valves. 



Tellidora bnrneti (Broderip and Sowerby) Plate 69, figures 1-lb 



Tellina burneti Broderip and Sowerby, 1829, Zool. Jour., vol. 4, No. 15, p. 362, pi. 9, 

 fig. 2. Found in the estuary of Mazatlan, among the shoals of large Pinnae 

 which are left dry at low water. — Hanley, 1846, Thes. Conch., vol. 1, Tellina, 

 p. 271, pi. 58, fig. 99 Salango. — Sowerby, 1867, Conch. Icon., vol. 17, Tellina, 

 species 199, pi. 35, figs. 199a, 199b. 



Tellidora burneti (Broderip and Sowerby), Hertlein and Strong, 1949, Zoologica, vol. 

 34, pt. 2, No. 9, p. 88.— Hertlein and Strong, 1955, Bull. Amer. Mus. Nat. Hist., 

 vol. 107, art. 2, p. 199. 



Adult specimens may reach a length of nearly 50 mm., white, the 

 valves unequal, the left valve is somewhat larger, convex, the right flattened 

 to depressed, the posterior side flexed and turned towards the right, ending 

 in a short, stout, truncated nose. Surface smooth or marked with fine lines 

 of growth and with irregular undulations on the beaks. Pallial line and 

 muscle scars deeply impressed. 



Range — Lower California southward to Ecuador. Panama: San Carlos; 

 Bucaro. Panama Canal Zone: Amador Beach, Balboa. Colombia: Isla del 

 Gallo. Ecuador: Santa Elena; Charapota; Portete; Sua; Galeras. 



Genus MERISCA Dall, 1900 



Type species by original designation, Tellina crystallina Wood. West 

 Atlantic. 



The shell is trigonal-ovate in shape, inequilateral and inequivalve, 

 the posterior end with a strong, ridged flexure, the left valve convex, the 

 right valve more or less depressed. The beaks are submedian, the anterior 

 side wide and rounded, the posterior side with a narrow but well-defined 

 rostral area which is terminated in a beaked end and in the right valve 

 bordered by an impressed ray and a change in sculpture. The surface is 

 sculptured with raised, concentric ridges or lamellae, closely or widely 

 spaced. The hinge is normal, the right valve with a strong, lateral socket 

 buttressed with a tooth on each side, the anterior set a little closer to the 

 cardinal teeth; the left valve has no lateral teeth, the hinge margins are 



