♦06 AXEL A. GLSSON 



Subgenus SCISSULA Dall, 1900 

 Type species by original designation, Tellina decora Say ( = r. similis 

 Sowerby). Recent, West Atlantic. 



The shell is usually small, elongate, and subelliptical, the posterior 

 side shorter than the anterior, the surface depressed or mildly inflated, 

 the texture thin, white or colored, sometimes glassy. Hinge as \r\ Moerella, 

 S.S. Surface with the usual growth line sculpture but in addition has a 

 pattern of oblique or diagonal lines which cross the concentrics usually at 

 high angles; these diagonal lines are most strongly developed over the 

 middle and anterior sections of the disk. 



Three species are regional. 



Key to Panamic-Pacific Scissula 



I. Oblique lines are relatively coarse, widely spaced and intersect the 

 basal margin at angles of about 40 degrees. There is a narrow, well- 

 marked, smooth ray in front of posterior-umbonal angle. Posterior area 

 well sculptured. 



M. (S.) Virgo 



II. Oblique lines much finer, more closely spaced and intersect the basal 

 margin at angles of 15 to 20 degrees. 



1. Entire surface of disk in front of the posterior angle covered more or 

 less uniformly by the oblique lines. 



M. (S.) varilineata 



2. Oblique lines on anterior and middle portions of shell disk terminating 

 sharply along a line running downward from the beak, the surface be- 

 tween it and the posterior angle wide, smooth and sculptureless. 



M. (S.) esmeralda, new species 



Moerella (Scissnla) yirgo (Hanley) Plate 72, figure 4 



Tellina v'lrgo Hanley, 1844, Proc. Zool. Soc. London, p. 143. — Hanley, 1846, Thes. Conch., 

 vol. 1, Tellina, p. 284, pi. 57, fig. 42.— Pilsbry and Olsson, 1943, Nautilus, vol. 

 56, No. 3, p. 79, pi. 8, fig. 5. 



Tellina (Scissula) virgo Hanley, Salisbury, 1934, Proc. Malacol. Soc. London, vol. 21, 

 pt. 2, p. 91, pi. 13, figs. 5, 6. — Maxwell Smith, 1944, Panamic Marine Shells, 

 p. 65, fig. 850C. — Hertlein and Strong, 1949, Zoologica, vol. 34, pt. 2, No. 9, 

 p. 86. 



With characters indicated in the key. This is a small delicate shell, 

 often found plentifully in beach drift but the valves seldom perfect. 



Range — Gulf of California to northern Peru. Panama: Bucaro; El 

 Lagartillo. Panama Canal Zone: Venado Beach. Colombia: Isla del Gallo. 

 Ecuador: Galeras. Peru: Tumbez. 



Bloerella (Scissula) Tarlllneata (Pilsbry and Olsson) 



Tellina (Scissula) varilineata Pilsbry and Olsson, 1943, Nautilus, vol. 56, No. 3, p. 79, 

 pi. 8, fig. 6. 



This species differs from M. virgo by its longer, heavier shell, and 

 more especially by its much finer sculpture, the diagonal lines intersecting 

 the basal margin at a much lower angle. 



Length 17 mm., height 9.75 mm., semidiameter 2.1 mm. Bucaro, 

 Panama. 



