CO 
Ors 
AVICULA. 
Myrituus, Linn., Gmel., Chem., &c. 
Avicuua, Cuvier, De Lamarck, Sowerby. 
GENERIC CHARACTER. 
Testa bivalvis, ineequivalvis, alata, ad unum latus pau- 
lulum hians: al@ inequales: cardo obsolete, obtuse 
unidentatus: ligamentum marginale. 
ANIMAL byssoferum. 
BIRDSHELL. 
Shell bivalve; unequal-valved, winged, gaping on one 
side : wings unequal : hinge with one obsolete obtuse tooth : 
ligament marginal. 
Animat furnished with a byssus. 
The shells of this genus are generally furnished with a 
very long wing-like process on that edge opposite to the 
gaping side, and this wing varies in proportion to the body 
of the shell in the different species. The inner border is 
generally of a darker colour, without that pearly lustre, 
which characterises the inside surface ; in some of the species 
(particularly in those with short wing-like processes) both 
valves are similar in this respect ; in others this peculiarity is 
predominant in, or is entirely confined to, the smaller valve. 
One indigenous species has been discovered amongst 
some coral from the Plymouth Sound, by that most zea- 
lous and successful investigator of British shells, C. Pri- 
deaux Esq. of Kingsbridge. 
