340 SOLENINiE. 



bifid ; ligament external, large, linear, marginal, supported 

 on a large prominent pad or fulcrum. 



Usually living buried vertically in the sand. 



The very natural group of the Solens or "Razor-fish," 

 usually live buried perpendicularly in the sand, penetrating 

 it by means of their large and powerful muscular foot. 

 The outer layer of their shell is formed of long, nucleated, 

 prismatic cells, placed very oblique to the surface, and the 

 inner layer of cell-structure is nearly homogeneous. The 

 long, linear, and narrow gills extend into the branchial 

 siphon, as in the Pholades, the elongated tubes of which 

 appear to be represented in this family by the long bran- 

 chial cavity. 



Sub-fam. SOLENIN^E. 



Siphons short and united. Foot more or less cylindrical 

 and obtuse. 



Shell transversely greatly elongated, gaping and truncate 

 at the extremities; beaks anterior or terminal. Hinge 

 usually with one tooth in each valve. Pallial line with 

 a deep, truncated sinus. 



Genus SOLEN, Linnaeus. 



Siphons very short, united, fringed. 



Shell transversely greatly elongated, nearly straight, sub- 

 cylindrical, margins parallel, ends gaping, beaks terminal. 

 Hinge with one primary tooth in each valve close to the 

 anterior extremity ; ligament long, external. Anterior mus- 

 cular scar elongated ; pallial impression with a short, square 

 sinus. 



