AMPHINEURA. 
The following Table shows the systematic arrangement of the Syste- 
matic 
arrange- 
ment. 
Mollusca adopted in the Shell Gallery : — 
Class I. — Amphineura. 
Order 1. — Polyplacophora. Chitons. 
„ 2. — Aplacophora. Neomenia, Chastodernia, etc. 
Class II. — Gastropoda. 
(Section Streptoneura.) 
Order 1. — Scutibranchia. Nerites, Top-shells, Ear-shells, Limpets. 
„ 2. — Pectinibranchia. Rock-snails, Whelks, Olive-shells, Harp-shells, 
Cones, Strombs or Wing-shells, Periwinkles, Carrier-shells, etc. 
(Section Euthyneura.) 
Order 1. — Opisthobranchia. Bubble-shells, Sea-hares, Umbrella-shells. 
„ 2. — Pulmonata. Land and freshwater Snails, False Limpets. 
Class III. — Scaphopoda. Tooth-shells (Dentalium). 
Class IV. — Lamellibranchia. Bivalved Molluscs. 
Order 1. — Protobranchia. Nucula, etc. 
„ 2. — Filibranchia. Anomia, Common Mussel, Ark-shells, etc. 
„ 3. — Pseudolamellibranchia. Pearl Oyster, Hammer Oyster, Wing- 
shells, etc. 
„ 4. — Eulamellibranchia. Freshwater Mussels, Cockles, Razor-shells, 
Ship-worms, etc. 
„ 5. — Septibranchia. Poromya, etc. 
Class V. — Cephalopoda. 
Order 1. — Tetrabranchia. Pearly Nautilus. 
„ 2. — Dibranchia. Octopus, or Poulp, Argonaut, Squids, and Cuttle 
fishes. 
Class I.— AMPHINEURA. 
The Molluscs of this class are characterized by bilateral symmetry, cases 1-3. 
The head and arms are situated at the opposite extremities of the 
elongated body, the gills, genital ducts and circulatory organs being 
paired and similar on both sides. The first order belonging to this 
division, the Polyplacophora, includes the " Ooat-of-mail shells," or 
" Sea-woodlice " (Chitonidm). They have their back armed with 
eight shelly plates which overlap one another like tiles, and, like 
woodlice, have the power of rolling themselves into a ball. These 
plates are imbedded at the sides into the fleshy mantle, beneath 
which, on each side of the foot, are arranged the gills. A Chiton 
differs in many respects from other Mollusca. It has a shell like an 
Isopod Crustacean, a heart down the back like a sea-worm, sym- 
metrical organs of reproduction on each side like the bivalves, a 
