MALACOZOA. TROPIOPODA. LAMELLiBRANCHIATA. 281 



When very young, the valves are extremely delicate, trans- 

 parent, milky white, or opaline, with splendent iridescent tints. 



Not uncommon on the sandy coast, and often cast ashore ; 

 also brought up by the fishing-lines. 



Tellina Fabula. Gmel. Svst. Nat. 3239.— Tellina Fabula. Mont. 

 Test. Brit. 61.— Tellina Fabula. Turt. Brit. Biv. 101.— Tellina 

 Fabula. Flera. Brit. Anim. 435. — Tellina Fabula. Lamk. Syst. 

 V.526- Ed. 2. vi. 197. 



Family IX. — Solenina. 



Animal much elongated ; with the mantle adhering 

 toward the borders, closed, open in front for the passage 

 of the foot, and forming behind a single tube, internally 

 double, and having two simple orifices ; a stout conical 

 foot terminating the body anteriorly ; two adductor 

 muscles, the anterior longitudinally extended, the pos- 

 terior roundish. 



Shell long, equivalve, extremely inequilateral, thin, 

 gaping at both ends, and covered with epidermis ; the 

 hinge with not more than two small prominent teeth in 

 each valve ; the ligament linear and dorsal ; the anterior 

 muscular impression long, the posterior elliptical. 



They live immersed in sand or mud, with the anterior 

 end lowest. 



Genus 1. Solen. 



Animal much elongated. The mantle adhering by its 

 borders, closed throughout its length, posteriorly forming 

 a single extensile tube, internally divided into two, of 

 which the orifices are simple, the anal smaller. Foot 

 stout, cylindrical, very extensile. Branchiae long, nar- 

 row, pointed backwards, posteriorly united. Mouth 

 small, with two pairs of elongated triangular labial palpi. 

 Anterior adductor muscle longitudinally extended, pos- 

 terior smaller. 



Shell much elongated, linear or oblong, equivalve, 

 very inequilateral, concentrically striated, with a thin 

 persistent horny epidermis, and open at both ends. 

 Umbones with the cardinal teeth small, generally two in 



