2 
SYSTEMATIC DISTRIBUTION. 
lary masses distributed to different parts of the 
body; one of the masses being placed over the 
gullet, and enveloping it like a collar. 
Linnaeus refers all the animals inhabiting shells to 
five different genera ; viz., Limax^ Ascidia^ Anomia^ 
CliOy and Sepia, These genera may be regarded 
as the types of the classes proposed by Cuvier. 
Poli had, before his time, considered three of them 
as orders, under the names of MoUusca Reptantia^ 
Suhsilentia, and Brachiata, 
This division of the animal kingdom is subdivided 
into five classes in the following manner : — 
A. Crawling on a foot placed under the body, - — • 
Pedif era. 
I. Gasteropoda, Gasteropods^ or Univalves^ 
which have a distinct head, furnished with 
eyes and tentacles, and are usually protected 
by a conical more or less spiral shell, often 
furnished with an operculum. 
II. CoNCHiFERA, ConcMfers^ or Bivalves. — 
Having the mouth placed between the gills, 
they and the body enclosed between the two 
leaves of the mantle, which are covered with 
two shelly valves united above by a ligament. 
B. Destitute of any foot. — Apoda. 
III. Brachiopoda, Brachiopodsy or Lamp Shells. 
— Having the mouth placed at the base of 
two spirally twisted ciliated arms, between 
the two leaves of the mantle, which axe co- 
