TABLE SHOWING THE CLASSIFICATION OF THE MOLLUSKS 

 DESCRIBED IN THIS CHAPTER 



Phylum 



MOLLUSCA 



Classes 

 AMFHINEURA 



(Bilaterally symmetrical 

 mollusks, having shell 

 composed of eight plates, 

 or devoid of shell. In- 

 cluding chitons and their 

 allies) 



GASTEEOPODA 



( Unsymmetrical univalve 

 mollusks, usually spiral- 

 ly coiled. Periwinkles, 

 whelks, snails, etc.) 



SCAPHOPODA 



(Molhmks u'ithout head, 

 eyes, or heart, with tri- 

 lobed foot and tubular 

 shell open at both ends. 

 The tooth-shells) 



Orders 



POLYPLACOPHOBA 



(Shell composed of eight plates) 



APLACOPHOBA 

 (Devoid of shell) 



OPISTHOBBANCHIATA 



(Branchice, when present, behind < 

 the heart) 



PROSOBKANCHIATA 



(Branchice situated in front of the 



heart) 



PULMOBTATA 



(Air-breathing mollusks) 



Suborders 



TECTI3RANCHIATA 



(Branchice more or less 

 covered by mantle ; shell 

 delicate and often rudi- 

 mentary ) 



NUDIBRANCHIATA 



(Devoid of shell and 



mantle, and without 



true branchiae) 



DIATOCARDIA 

 ( Usually two auricles, two 



branchice, and two neph- 



ridia) 



MONOTOCARDIA 

 (One auricle, one bran- 



chia, one nephridium) 



