252 FUNCTIONS AND INSTINCTS. 



These animals are said to be taken by means 

 of a long pole, which is introduced between the 

 valves of their shells when open ; they imme- 

 diately close them, and will not quit their hold, 

 till they are landed. They are a principal arti- 

 cle of food in the Moluccas, especially the young 

 ones, which may be kept alive a long time. 



The wing-shell * belonging to the unimuscular 

 section, has long been celebrated, on more than 

 one account, from a very early period. They 

 are called wing-shells, or fin-shells, because they 

 are shaped somewhat like a wing or fin, their 

 Latin name (Pinna) is supposed to have been 

 given them because of their resemblance to the 

 plumes which the Roman soldiers wore in their 

 helmets. They are sometimes very large, some 

 are said to measure three feet in length : their 

 substance differs from that of most shells, being 

 of a fibrous structure, and they appear to be 

 formed of transverse imbricated laminae, they 

 are also semi-transparent and very thin. Their 

 byssus has been long celebrated, for it is men- 

 tioned by Aristotle. 2 Its Creator has provided 

 this animal, as we learn from Poli, with a pair 

 of bifid muscles with which it spins this sub- 

 stance, which emerges from the shell opposite 

 the hinge ; like the thread of the muscle it 

 terminates in a sucker, and with it the animal 



1 Pinna. 2 See Appendix, note 24. 



