162 THE HISTORY OF CREATION. 
and also to the Cuttle-fish (through the Butterfly-snails). 
The more highly developed Snails, with large heads 
(Delocephala), can be divided into Snails with gills 
(Branchiata) and Snails with lungs (Pulmonata). Among 
the latter are the Land-snails, the only Molluses which have 
left the water and become habituated to a life on land. 
The great majority of Snails live in the sea, only a few live 
in fresh water. Some River-snails in the tropics (the 
Ampullaria) are amphibious, living sometimes on land, 
sometimes in water, and at one time they breathe through 
gills, at another through lungs. They have both kinds of 
respiratory organs, like the Mud-fish and Gilled Newis 
among the Vertebrata. 
The fourth and last class, and at the same time the most 
highly developed class of Molluscs, is that of the Cuttles, or 
Poulps, also called Cephalopoda (foot attached to the head). 
They all live in the sea, and are distinguished from Snails 
by eight, ten, or more long arms, which surround the mouth 
ina circle. The Cuttles existing in our recent oceans—the 
Sepia, Calamary, Argonaut, and Pearly Nautilus—are, like 
the few Spiral-gill Lamp-shells of the present time, but a 
poor remnant of the host which represents this class in the 
oceans of the primordial, primary, and secondary periods. 
The numerous fossil “Ammon’s horns” (Ammonites), “ pearl 
boats” (Nautilus), and “thunderbolts” (Belemnites) are evi- 
dences of the long since extinct splendour of the tribe. 
The Poulps, or Cuttles, have probably developed out of a 
low branch of the snail class, out of the Butterfly-snails 
(Pteropoda) or kindred forms. 
The diffesent sub-classes and orders, distinguished in the 
four classes of Molluscs, whose systematic succession is 
