392 AXEL A. OLSSON 



D. Pallial sinus shorter, not reaching to the anterior adductor scar or 

 merely touching it, its end rounded and leaving a small, triangular 

 space between the sinus and the adductor scar. 



Da. Shell elongated, its length nearly twice its height. 



6. Average length about 40 mm., usually deep rose-red, rarely white, its 

 surface depressed. Sculpture strong, formed by regular, narrow, con- 

 centric ribbons between incised lines. 



E. ecuadoriana 



7. Shell smaller (usually 35 mm., or less), solid, white or rose-red. Sculp- 

 ture usually stronger in the middle. The anterior-ventral margin is 

 weakly crenulated and the anterior adductor scar is bordered by a 

 thickened ray. 



E. inaequistriata 

 Db. Shell relatively solid. Surface sculptured with strong, uniform, con- 

 centric ribbons. 



8. Shell oblong-elliptical, generally less than 45 mm. in length, color 

 white or pink. 



E. simulans 

 Dc. Texture thinner, surface sculpture weak, the umbones often plain, 

 glossy. 



9. Shell small, length 35 mm., or less. 



E. mantaensis 



10. Shell larger, the anterior side much the longer. 



E. prora 



Eurytellina (Eurytelllna) laceridens (Hanley) Plate 68, figure 1: 



Plate 71, figures 8, 8a 



Tellina laceridens Hanley, 1844, Proc. Zool. Soc. London, p. 61 Tumbez. — Hanley, 1846, 



Thes. Conch., vol. 1, Tellina, p. 243, No. 40, pi. 61, fig. 168.— Sower by, 1867, 



Conch. Icon., vol. 17, Tellina, pi. 20, fig. 104. 

 Tellina {Angulus) eburnea Hanley, Dall, 1910, Proc. U.S. Nat. Museum, vol. 37, No. 



1704, pp. 160, 270, pi. 28, fig. 3. (Not eburnea Hanley, 1844). 

 Tellina {Eyrytellina) laceridens Hanley, Hertlein and Strong, 1949, Zoologica, vol. 34, 



pt. 2, No. 9, p. 75. 



Shell elongate, nearly equilateral, the posterior side narrower, its end 

 concavely or obliquely subtruncate. The shell grows to a fair size (length 

 up to about 85 mm.), solid, porcellaneous white, often with small remnants 

 of a thin, deciduous, buff-colored periostracum. Valves are subequal, of 

 low convexity, often appearing as if flattened across the middle of the disk, 

 the posterior end only mildly flexed. Surface is nearly smooth except for 

 wide, flattened concentric ribbons which show indistinctly on the anterior 

 end and along the ventral side, subobsolete elsewhere. The rostral area is 

 narrow, flat or excavated, wrinkled and often radially striate, the defining 

 umbonal angle low. Interior of the valves usually thickened so that the 

 subequal adductor scars and the pallial lines are plainly visible and deeply 

 impressed. The upper limb of the pallial sinus is sinuous, highest just be- 

 hind the line of the beak, sometimes nearly straight, extending from the 

 posterior adductor to the lower edge of the anterior adductor but enclosing 

 below it a small, triangular area, largely confluent with the pallial line 

 below. 



Length 55.5 mm., height 31 mm., diameter 12.6 mm. Bucaro, Panama. 



Length 7S mm., height 36.7 mm., diameter 13.7 mm. San Francisco, 

 Ecuador. 



Length 83.3 mm., height 40.6 mm., semidiameter 7.8 mm. San Fran- 

 cisco, Ecuador. 



