CONCHIFEEA. 466 



trically furro-^ed ; lunule impressed ; ligament external ; epi- 

 dermis dark; hinge-teeth 2.2, the anterior tooth of the right 

 valve large and thick ; anterior pedal scar distinct ; pallial line 

 simple. 



Animal vnth. mantle open; margins plain or slightly fringed ; 

 siphonal orifices simple ; foot moderate, tongue-shaped ; lips 

 large, palpi lanceolate ; gills nearly equal, united behind, and 

 attached to the siphonal band. 



The animal otAstarte horealis is shown in Fig. 258; mantle- 

 margins free, plain, slightly cirrated in the branchial region ; 

 united posteriorly by the branchial septum, forming a single 

 excurrent orifice ; pedal muscles {p p')) distinct from adductors ; 

 gills flat, finely striated, destitute of internal partitions ; outer 



Fig. 25S. Astarte borealis, var. semi-sulcata, Leach, |-. Wellington Channel. 



gill narrow, elliptical, with a simple margin ; inner gill grooved, 

 conducting to the mouth. 



Distrihution, 20 species. Behring's Straits, "Wellington Chan- 

 nel, Kara Sea, Ochotsk, United States, Norway, Britain, 

 Canaries, ^gean (30 — 112 fathoms). 



Fossil, 285 species. Carb. — . North and South America 

 Europe, Thibet. 



? Digitaria, Wood ; Tellina digitaria, Lower Mediterranean, 



Fossil, Pliocene, Britain. 



GouLDiA, C. B. Adams. 



Shell minute, triangular, furrowed • hinge like Astarte, with 

 lateral teeth ; pallial line simple. 

 Dictrihution , 7 species. Panama, West Indies. 



^ 3 



