TABLE SHOWING THE CLASSIFICATION OF THE MOLLUSKS 
DESCRIBED IN THIS CHAPTER 
Classes 
AMPHINEURA 
(Bilaterally symmetrical 
mollusks, having shell 
composed of eight plates, 
or devoid of shell. In- 
cluding chitons and their 
allies) 
GASTEROPODA 
(Unsymmetrical univalve 
mollusks, usually spiral- 
ly coiled. Periwinkles, 
whelks, snails, ete.) 
SCAPHOPODA 
(Mollusks without head, 
eyes, or heart, with tri- 
lobed foot and tubular 
shell open at both ends. 
The tooth-shelis) 
Phylum 
MOLLUSCA 
Orders 
POLYPLACOPHORA 
(Shell composed of eight plates) 
APLACOPHORA 
(Devoid of shell) 
OPISTHOBRANCHIATA 
(Branchice, when present, behind 
the heart) 
PROSOBRANCHIATA 
(Branchic situated in front of the 
heart) 
PULMONATA 
(Air-breathing mollusks) 
300 
Suborders 
TECTIBSRANCHIATA 
(Branchie more or less 
covered by mantle; shell 
delicate and often rudi- 
mentary ) 
NUDIBRANCHIATA 
(Devoid of shell and 
mantle, and without 
true branchie) 
DIATOCARDIA 
(Usually two auricles, two 
branchice, and two neph- 
ridia) 
MONOTOCARDIA 
(One auricle, one bran- 
chia, one nephridiwm) 
