14 BIVALVES SOLEN. 



few, viz. twenty-three, yet their shapes, and general ap- 

 pearance, are exceedingly varied. 



In some of the species, as in the Solen Siliqua, Vagina, 

 &c* &c. the breadth of the shell is in the proportion of 

 about seven to one of its length, thereby giving it a re- 

 semblance to the handle of a knife, or sheath of a razor- 

 strop; some, on the contrary, though possessing nearly 

 the same proportions, are curved or bent, like the scab- 

 bard of a scimitar, as the Solen Ensis, &c. &c. 



In others, the form approaches nearer to some of the 

 truncated species of the precedmg genus, being swollen 

 orpufFed-up like a bladder. And other specimens afford 

 a likeness to a Cockle or Cardium. However, the surest 

 criterion how to class the Solen, is by observing both 

 ends of the shell, which invariably will be found open or 

 gapirg. 



The next characteristic is derived from the hinge, 

 w hich usually is supplied with one subulate tooth ; yet it 

 often occurs that this tooth is found double, though not 

 always inserted in the opposite valve; 



The genus Solen, for the most part, contains but little 

 beauty ; there are, indeed, some few exceptions— such as 

 the Solen Radiatus, Rosens, &c. &c. these, from being 

 rayed with purple and white, or having a fine pink co- 

 lor, may perhaps claim admiration ; but whatever beauty 

 they may possess, they are infinitely surpassed by innu- 

 merable species in the other genera of Bivalves. 



Most of the species of Solen are found covered with a 

 thin cuticle or epidermis, which, if not removed, ren- 

 ders the colors beneath very obscure, and, in some instan- 

 ces, undiscoverable. There is one species only which is 

 said to produce pearls, viz. Solen Macha. 



The European and Northern seas afford by far the 



