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DISTRIBUTION OF ANIMALS. 
[part i. 
MOLLUSCA. 
The Mollusca are usually divided into five classes as 
follows : — 
Classes. 
I, Cephalopoda 
II. Gasteropoda 
III. Pteropoda 
IV. Brachiopoda 
V. Conchifera 
Cuttle-fish. 
Snails and aquatic Univalves. 
Oceanic Snails. 
Symmetrical Bivalves. 
Un symmetrical Bivalves. 
The Gasteropoda and Conchifera alone contain land and 
freshwater forms, and to these we shall chiefly confine our 
illustrations of the geographical distribution of the Mollusca. 
The classification followed is that of Dr. Pfeiffer for the 
Operculata and Dr. Yon Martens for the Helicidce. The 
families chiefly referred to are - 
Class II.— GASTEROPODA. 
Order 2. — Pulmonifera. 
Fam. 
I I. Helicidse. 
2, Limacidse. 
3. Oncidiadee. 
4. Limnseidse. 
5. Auriculidse. 
6. Aciculidae. 
7. Diplommatinidee. 
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