Lamarck’s Genera of Shells. 307 
cardinal teeth ; two lateral teeth, the posterior nearest the hinge. 
Muscular impressions simple. 
The corbis is principally distinguished from the lucina by 
the animal which inhabits the shell, also by not having one of 
the muscular impressions lengthened into a band ; and from the 
Tellina, by wanting the irregular fold on the anterior margin. 
Type. Corbis fimbriata*. (Venus fimbriata. Linn.) 
Shell transversely oval, gibbous, longitudinally striated ; 
transverse furrows wavy; margin indented. Indian Ocean. 
3 Species. Pl.'v. Fig. 47. 
4. Lucina. 
Shell suborbicular, inequilateral ; beaks small, pointed, 
oblique. Two diverging cardinal teeth (one bifid,) which vary 
or disappear with age. Most species have two lateral teeth, 
the posterior nearest the cardinal ; some have no lateral teeth. 
Two very separate muscular impressions, the posterior pro- 
duced in the form of a band, sometimes very long, and extend- 
ing to the middle of the valve. Ligament always external, 
and apparent. 
Type. Lucina Jamaicensis +. (Venus Jamaicensis. Chemn.) 
Shell lentiform, rough, lamellar-sulcate; internally rather 
clay-coloured ; lamellz short, concentric; anterior side of both 
valves angular. Antilles. 20 Species. Pl.v. Fig. 48. 
5. Donax f. 
Shell transverse, equivalve, inequilateral ; anterior side very 
short and obtuse, and, as it were, truncated. 
Two cardinal teeth, either on both valves, or only on one: 
one or two lateral teeth, more or less distant. Ligament short, 
external, inserted in the place occupied by the lunula. 
This genus is characterized by its rather flattened and almost 
triangular shell, and by having, at the hinge, beside the cardi- 
nal teeth, one or two rather distant lateral teeth, separated from 
the cardinal teeth, and analogous to the lateral teeth of the 
* Fringed, or scalloped. + Of Jamaica. 
t Aovaf, a reed, or arrow. Donax is used by Pliny as the name of a sea- 
fish.—32. 11. 
X.2 
