PANAMIC-PACIFIC PELECYPODA 387 



depressed to weakly convex, white, or in shades of pink. Posterior or prin- 

 cipal line of flexure is always present and sharply defined, the sulci over 

 the posterior-dorsal area generally finer, more closely crowded, and not 

 flexed except in some cases adjacent to the dorsal margin. On the anterior 

 one-third of the disk, there is often a second line of flexure, the sulci there 

 are bowed convexly to a varying degree, sometimes partly obsolete or re- 

 placed along the umbonal slope by a smooth tract, Pallial sinus deep, free 

 or with its upper limb reaching across to the anterior adductor scar. 



In Rombergia Dall (type species, S. rombergi Morch of Caribbean 

 waters) the upper limb of the pallial sinus is attached to the pallial line 

 a short distance behind the anterior adductor scar; this is a character of 

 minor importance. 



Strigilla (Strigilla) disjoncta Carpenter Plate 73, figures 1-lc 



Strigilla dis'juncta Carpenter, 1856, Proc. Zool. Soc. London, p. 160. — Strong and Hertlein, 



19+9, Zoologica, vol. 34, pt. 2, No. 9, pi. 1, fig. 20. 

 Strigilla sincera Hanley, Maxwell Smith, 1944, Panamic Marine Shells, p. 65, fig. 845. 



S. ? sincera Hanley, 1844. 



Shell large, (length 30 mm. or more), suborbicular, slightly inequivalve, 

 the left valve is smaller, depressed to slightly convex, relatively thin, white. 

 The anterior side is about half the length of the posterior, evenly rounded 

 at the end and often slightly flexuous. The posterior-dorsal submargin is 

 narrowly flattened. Sculpture is fine and uniform over most of the surface. 

 On the umbones, the concentric lines are fine and threadlike and become 

 almost invisible close to the beaks where they are nearly concentric with 

 the shell margin. Ventrally, the sulci are coarser and more strongly oblique 

 and over the anterior-umbonal slope bunched together into a small infold. 

 The posterior-umbonal line of divarication is sharp and straight, the sulci 

 above it fine and crowded together. Pallial sinus large, not extending to 

 the anterior adductor scar. 



Length 45 mm., height 40.5 mm., semldlameter 9.3 mm. (a large right 

 valve from Mompiche, Ecuador). 



Easily known by its large size, depressed surface, and ovate-elliptical 

 shape. The sculpture is extremely fine. The color is white, very rarely flushed 

 with pink. Young shells are thin and glassy. Best known in the literature 

 as S. sincera. Hedley has shown that the name "sincera" should be applied 

 to an Australian species. 



Range — Nicaragua to northern Peru. Panama: Panama City; Las 

 Tablas; Bucaro; Coiba Island (USNM). Colombia: Isla del Gallo. Ecuador: 

 Santa Elena; Charapota; Sua; Mompiche. Peru: Tumbez. 



Strigilla (Strigilla) carnaria (Llnn6) Plate 73, figures 4, 4a 



Tellina carnaria Linne, 1758, Syst. Nat. ed. 10, p. 676. — Hanley, 1846, Thes. Conch., vol. 

 1, p. 260, pi. 56, fig. 38. 



Shell of medium size (average length about 22 mm.), suborbicular, the 

 anterior side about half the length of the posterior, its margin broadly 

 rounded or subtruncate. Surface with the characteristic sculpture of the 

 genus and as noted in the key having two lines of divarication, a posterior 

 and anterior; that along the anterior slope is rather broad or obtuse, often 

 partly obliterated or smooth. Posterior-dorsal area with a smooth, even 

 slope, the incised lines become crowded and hairlike. Pallial sinus large and 



