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valve, with a fold on the anterior part, and short beaks. One or two 
hinge -teeth, and remote lateral teeth. 
The shells of this genus are chiefly known by the inflexion or irre- 
gular fold on their fore part. The hinge-teeth are either one on each 
valve ; two on one, and one on the other ; or two on each valve : and 
the lateral teeth are most frequently two, which are compressed. 
Lamarck particularizes the following, as being the species which 
are found in the neighbourhood of Paris : T. patellaris, much resem- 
bling T. remies, Linn. T. scalar oides, T. cavinulata , T. sinuata, T. dona- 
cialis, T. rostralis , T. corneola, T. pusilla, T. rudis. 
The habitat of the rostrated shell, represented Plate XIII. Fig. 4, 
I am not acquainted with ; nor, though I have placed it here, am I 
satisfied of this being its most appropriate place, being entirely unac- 
quainted with its hinge. 
CXXI. Capsa. A transverse shell, with two cardinal teeth in one 
valve, and one entering double tooth on the other. 
This genus is exemplified by Venus dejlorata, or Capsa rugosa, 
Linn. List. Conch. Tab. 425, Fig. 273. The shells of this genus are 
not, I believe, known fossil. 
CXXII. Solcn. An equivalved, transversely elongated bivalve, 
gaping on each side ; the hinge-teeth single in each valve, or double 
in one valve ; the beaks exceedingly small ; the ligament external, 
and most frequently near to the extremity of the shell. 
The sanguinolarice are distinguished from the Salens by having 
two hinge -teeth in each valve ; the glycemeres, by having no hinge - 
teeth; and the myce, by having an inner ligament, and by their pio- 
jecting compressed tooth in the left valve, to which the ligament is 
attached. 
Lamarck describes five fossil species of this genus, as found in the 
environs of Paris : S. vagina, S. fragilis, S. effusus, S. strigilatus, 
S. appendiculatus. Of S. vagina he remarks, that he found none more 
than three inches in their transverse length. S. fragilis approaches 
