146 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
characterized by its having the columella strongly plaited, with the base 
of the aperture entire. 
The family of the Plicacea consists of the two following genera, neither 
of which is very numerous in species : 
ToRNATELLA. PyRAMIDELLA. 
TORNATELLA, Lamarck. 
Testa ovalis, cylindracea, plerumque transversim striata, raro levissima, 
spira brevi, apice acuto; apertura longitudinali, superné angustata, 
inferné integra, rotundata ; columella incrassata, valdé plicata ; la- 
bro simplici, solido, acuto. 
The very wide range of characters which were selected by Linnzus for 
the determination of genera induced many inaccuracies in his method of 
classification which might certainly have been avoided, if, instead of ge- 
neralizing upon the external variations of the shell, he had pursued a more 
searching inquiry, like Adanson and Forskael, into the nature of its 
animal inhabitant. His genus Voluta, for example, founded upon the 
character of the columella being obliquely plaited, included both phyto- 
phagous and zoophagous mollusks, animals both with and without pro- 
boscis or branchial siphon. The presence or absence of these organs, 
however, distinguishing the plant-eating from the flesh-eating mollusks, 
is still indicated to a certain extent in the shell by the basal formation of 
the aperture ; and Bruguiére, the conchologist of the ‘ Encyclopédie Mé- 
thodique,’ appears to have sagaciously detected the difference between 
the shells of the true Volute, and those which were subsequently selected 
by Lamarck for the formation of this genus, the base of the aperture 
being sinuated or canaliculated in the one, and entire in the other. But 
the alteration proposed by Bruguiére was little or no improvement upon 
the arrangement of Linnzus; for in removing them to his new genus 
Bulimus, they became associated with a miscellaneous assemblage of mol- 
