176 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
Family 8. CANALIFERA. 
Testa canaliculata, canali plus minusve elongato, interdum brevissimo ; 
anfractibus varicibus interdum ornatis, labro «tate non mutabili ; 
columella interdum plicata. 
The Canalifera are very numerous, and constitute an interesting family 
of mollusks: they are distinguished, first, in being armed with a strong 
retractile proboscis for the capture of prey; and secondly, in having a 
siphon of various length for the purpose of conveying the water freely to 
the branchial cavity. The last of these peculiarities exercises the great- 
est influence on the formation of the shell, for it is always more or less 
canaliculated at the base for the protection or passage of that organ. 
Lamarck was the first to separate this portion of the zoophagous Gaste- 
ropoda under the title of Canalifera; De Blainville nearly followed his 
example, substituting the word Siphonostoma ; but Latreille divided the 
family into two. He proposed that the fusiform genera, in which the 
shell is mostly plaited on the columella, should be separated under the 
name of Fusiformia, and that those in which the shell is ornamented with 
varices should be set apart under that of Varicosa. We have, however, 
followed Lamarck in determining this family upon the sole character of 
the basal canal which the shells exhibit for the passage of the siphon ;. 
they undoubtedly present an immense diversity of form, but may never- 
theless be fairly distributed without further subdivision into the following 
ten genera : 
CERITHIUM. PLEUROTOMA. 
TURBINELLUS. PyRULA. 
‘CANCELLARIA. Murex. 
FASCIOLARIA RaNELLA. 
Fusus. TRITON. 
