30 BIVALVES SOLEN. 



In some of the species, as in the S. siliqua, S. vagina, 

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

 seven to one of its length, thereby giving it a resemblance 

 to the handle of a knife, or sheath of a razor-strop; some, 

 on the contrary, though possessing nearly the same pro- 

 portions, are curved or bent, like the scabbard of a scimi- 

 tar, as the S. ensis, &c. In others, the form approaches 

 nearer to some of the truncated species of the preceding 

 genus, being swollen or puffed up like a bladder. How- 

 ever, by observing both ends of the shell, which will be 

 invariably found open or gaping, there can be little 

 danger of mistaking the Solen for any other genus. 



The next characteristic is derived from the hinge, which 

 is usually supplied with one subulate tooth, often found 

 double, though not always inserted in the opposite valve. 



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

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

 the S. radiatus, S. roscus, &c. these, from being rayed 

 with purple and white, or having a fine pink color, may 

 perhaps claim admiration; but whatever beauty they 

 may possess, they are infinitely surpassed by innumera- 

 ble 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, renders 

 the colors beneath obscure, and, in some instances, un- 

 discoverable. There is only one species which is said to 

 produce pearls, viz. S. macha. 



The European and Northern Seas afford by far the 

 greatest proportion of the shells of this genus. They are, 

 however, found in the Indian, American, and Mediter- 

 ranean seas. The river Tees affords one species, viz, S. 

 crispus. They often reside among zoophites. 



