Gl 
dassecl by linnseus with the Chama), Hiatella koom viit. 
(Mya of Linnaeus), and Isocardia. The last ge- Nat. Hist. 
nus includes the rare and elegant shell Isocardia 
Moltkiana—the Chama Moltkiana of Gmelin. 
Table 10. The families Arcacea^ Trigoni- 
ana^ and part of the Naiada, Amongst them 
are the Cucullaea auriculifera (Area cuculis. 
GmeL), several species of the genera Area and 
Pectiinculus, and the genus Nucula (the two 
latter were confounded with the Arcse, by Lin¬ 
naeus) ; the genus Trigonia, and part of the ge¬ 
nus Unio (Mya of Linn.), some species of which 
furnish pearls of considerable size and beauty. 
Several new species of Unio from North Ame¬ 
rica. 
Table 11 . Unio continued; and the genera 
Hyria, Anodonta (Mytilus. Linn.), and a single 
valve of the Iridina ovata (?) a very rare genus, 
of which Lamarck gives but one species. Also 
the families Chamacea, Tridacnea, and part of 
the Mytilacea. Of the Chamacea, is a specimen 
of the Diceras arietina, the only known species 
of this genus, and hitherto not found as a recent 
shell; also various species of Chama ; and three 
species of the fresh-water genus Ether la, all of 
which are rare. 
Table 12. The second Order of this class, 
Conchifera unimusculosa, begins with the family 
Tridacnea^ comprehending the genera Tridacna 
and Hippopus-—Some shells of the former ge¬ 
nus, of the species Tridacna gigas, are the 
largest that are known ; they are said to have 
been 
