38 BIVALVES. — SOLEN. 



SOLEN. — Razor-sheath or Knife-handle. 



Animal — an Ascidia: Shell bivalve, oblong, open at both 



ends; hinge with a subulate reflected iooth, often double, 



and not inserted into the opposite valve. 



THE number of species in this genus is thirty-five, and 

 in their general appearance they are exceedingly varied. 



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. roseus, &c. these, from being rayed with 

 purple and white, or having a fine pink colour, may perhaps 

 claim admiration; but whatever beauty they may possess, 

 they are infinitely surpassed by innumerable 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 colours beneath obscure, and, in some instances, undis- 

 coverable. 



