PANAMIC-PACIFIC PELECYPODA 389 



Strigilla (Strigilla) erviUa (Fhilippi) Plate 73, figures 6, 6a 



Tellina ervilia Fhilippi, 1846, Zeit. f. Malakozool., Jahrg. 3, p. 20, No. S Mazatlan. 

 Probably Strigilla lenticula (Fhilippi), Dall, 1900, Free. U.S. Nat. Museum, vol. 23, 



No. 1210, p. 305.— Hertlein and Strong, 1949, Zoologica, vol. 34, pt. 2, No. 9, 



p. 96, pi. 1, fig. 21. 



Shell of medium size (length to about 11 mm.), subcircular to sub- 

 ovate, plump with a high, submedian umbone and beak, white or faintly- 

 suffused with pink. The posterior flexure is sharp, the incised lines meeting 

 along it at angles of 70 to 80 degrees, the anterior flexure is absent, the 

 incised lines across the anterior-umbonal slope showing no change of di- 

 rection except close to the margin where they are slightly undulated by a 

 weak fold in the substance of the shell itself. The sculpture is regular and 

 neat over the whole disk, the incised lines are close-set and forming elevated 

 threadlets, smooth on top, but finely etched by concentric striations in 

 their intervals. Interior deep and smooth, the lateral teeth strong. 



Length 11.1 mm., height 10.8 mm., diameter 3.3 mm. (a right valve, 

 Santa Elena, Ecuador). 



This is perhaps the species determined by Hertlein and Strong as S. 

 lenticula (Philippi) from Corinto, Nicaragua, but their figure shows a more 

 circular shell with coarser sculpture. The species is easily recognized by its 

 ovate, nearly equilateral form, and characteristic sculpture. 



Range — Lower California to Ecuador. Panama: Bucaro; El Lagartillo 

 near Las Tablas. Colombia: Isla del Gallo. Ecuador: Punta Blanca; Santa 

 Elena. 



StrigiUa (Strigilla) dichotoma (Philippi) Plate 73. figure 2 



Tellina dichotoma Philippi, 1846, Zeit. f. Malakozool., Jahrg. 3, p. 20, No. 4 Mazatlan. 



The shell is small, subovate, slightly inequilateral, the posterior side a 

 little longer and narrower, its dorsal margin descends into a widely rounded 

 end, the surface of the valves depressed to slightly convex, white in color. 

 The posterior or principal line of divarication is sharp, the sulci meeting 

 at acute angles along it and continue across the posterior-dorsal area in 

 straight lines, rather coarsely spaced. The sulci are strong over the main 

 portion of the disk and stand at angles of 60 to 70 degrees to the margin; 

 they are more irregular over the anterior slope, with shorter threads, to 

 the number of two or three, intercalated between some of them; nearer 

 the anterior margin they tend to become concentric. 



An average specimen measures: length 8:5 mm., height 6.4 mm., semi- 

 diameter 2.2 mm. a left valve. 



This species has the shape and size of S. cicerula but the surface of the 

 valves is more depressed and the sulci are less steeply inclined and more 

 closely spaced over the middle zone of the disk. A peculiar feature of 

 the species is the splitting of the sulci by twos or threes across the anterior- 

 umbonal area, a character which evidently suggested its name to Philippi. 



Range— GxxM of California to Ecuador. Mexico: Mazatlan (PhiHppi). 

 Panama: Guanico. Ecuador: Punta Blanca. 



