SOLENIDAE 443 



5 to 6 inches in length, oval-oblong in shape, laterally compressed and 

 moderately thin. Periostracum varnish-like and olive-green. Interior glossy 

 and whitish with a purplish flush. Internal rib under teeth descending ob- 

 liquely toward the anterior end. Animal without dark coloration. The 

 variety nuttalli Conrad is a synonym. Do not confuse with 5. alta. An abun- 

 dant, edible species found in mud and sand on ocean beaches. 



Siliqua alta Dall Dall's Razor Clam 



Arctic Ocean to Cook's Inlet, Alaska. Russia. 



4 to 5 inches in length, similar to panda, but chalky-white inside, more 

 truncate at both ends, a heavier shell, and with a stronger, narrower and 

 vertical (not oblique) rib on the inside. 5. viedia Sowerby from the same 

 region may possibly be the young of this species, although it is blushed with 

 purple inside. 5. alta is common and edible. 



Genus Ensis Schumacher 1817 



The Jackknife Clams closely resemble Solen, but the left valve has 2 

 vertical, cardinal teeth, and each valve has a long, low posterior tooth. 



Eiisis directus Conrad Atlantic Jackknife Clam 



Plate 30k 



Labrador to South Carolina. Florida? 



Up to 10 inches in length, 6 times as long as high, moderately curved 

 and with sharp edges. Shell white, covered with a thin, varnish-like, brown- 

 ish-green periostracum. Common on sand-flats in New England. Edible. 



Ensis minor Dall from both sides of Florida to Texas rarely exceeds 3 

 inches in length, is more fragile, relatively longer, and is more pointed at 

 the free end (not the end with the teeth). Internally it has purplish stains. 

 Moderately common between tide marks. Some workers consider this a sub- 

 species of directus. E. megistus Pilsbry and McGinty are probably 5 -inch- 

 long specimens of minor. 



Ejjsis myrae S. S. Berry Calif ornlan Jackknife Clam 



Southern California. 



2 inches in length, with much the same characters as In directus. This is 

 the only Ensis in California and It is not very common. It has been errone- 

 ously called calif or7iic7is Dall which, however. Is a more southerly species. 

 For a new name for the Californian Ensis, consult future works by Pacific 

 Coast students (probably S. S. Berr)').^ 



^ Since appeared Aug. 1953 ^^ Trans. San Diego Soc. Nat. Hist., vol. 11, p. 398. 



