CONCHOLOGICAL MANUAL. 



ABIDA. Leach. A genus founded on a species of Pupa, which 

 has the peristome slightly reflected, and numerous plaits in the 

 aperture. Pupa Juniperi, Pupa secale, Draparnaud. Great Britain ; 

 also Central and Southern Europe. 



ABRA. Leach. A genus composed of Amphibesma tenue, pris- 

 niaticum, and other small thin species. British Channel and ' 

 Mediterranean. Fam. Mactracea. 



ABSIA. Leach. Lithotrya, Sowerby. Fam. Pedunculated Cir- 

 ripedes. 



ACAMAS. Montfort. Belemnites multiforatus, Blainville. A 

 species described as being perforated at the apex, by a stellated 

 perforation. No species of Belemnite at present known agreeing 

 with the description ; it is supposed to have been taken from a 

 broken specimen. 



ACANTHOCHETES. A name given to a species of Chiton having 

 bunches of bristles at the sides of the valves. 



ACARDO. Commercon. Described from a pair of bony plates, 

 taken from the vertebrae of the Whale, and mistaken for a bivalve 

 shell, destitute of a hinge. 



ACARDO. Swainson. A generic term applied by Swainson to the 

 nearly toothless species of Cardium, named C. edentulum by some 

 authors ; C. Greenlandicum by others: fig. 123*. 



ACASTA. Leach. Order, Sessile Cirripedes, Lamarck. Balanus 

 Montagui, Sowerby. A small genus separated from Balanus, on 

 account of the cup-shaped base, but re- united by Sowerby, who 

 shews, in his Genera of Shells, that this is a merely accidental 

 circumstance, resulting from the situations in which the shells ac- 

 quire their growth. If, for instance, the Balanus be attached to 



