APPENDIX 203 
Order 6. Hemiptera. Bugs. Insects with two pairs of wings, or 
wingless, with sucking mouth-parts in form of a jointed proboscis, 
and incomplete metamorphosis. Ex. Aphis. 
Order 7. Lepidoptera. Butterflies and moths. Insects with two 
pairs of scale-covered wings, sucking mouth-parts in form of a long, 
unjointed proboscis, and complete metamorphosis. Ex. Bombyx. 
Order 8. Diptera. Insects with one pair of wings, sucking mouth- 
parts, and complete metamorphosis. Ex. House fly. 
Order 9. Hymenoptera. Insects with two pairs of wings, biting 
and licking mouth-parts, and complete metamorphosis. Ex. Bee. 
PHYLUM VI. MOLLUSCA 
Animals without paired locomotory appendages, and with a soft, 
unsegmented body, which is usually enclosed in a calcareous shell. 
Class 1. Amphineura. Symmetrical mollusks without a shell or 
with one composed of eight pieces in a longitudinal row. Ex. 
Chiton. 
Class 2. Scaphopoda. Symmetrical mollusks with a cylindrical 
shell. Ex. Dentalium. 
Class 3. Gastropoda. Snails. Mollusks with an asymmetrical, spiral 
shell and a single mantle cavity. 
Order 1. Opisthobranchiata. Marine snails with posterior gills. 
Ex. Aeolis. 
Order 2. Pulmonata. Freshwater and land snails, without gills 
but with lungs. Ex. Helix. 
Order 3. Prosobranchiata. Mostly marine snails with anterior 
gills. Ex. Fulgur. 
Class 4. Pelecypoda. Symmetrical mollusks with a bivalve shell 
and paired mantle cavities. Ex. Unio. 
Class 5. Cephalopoda. Mollusks with a large head, which bears a 
number of long arms, and with a single mantle cavity. 
Order 1. Tetrabranchiata. Cephalopods with four gills and a 
large convoluted shell. Ex. Nautilus. 
Order 2. Dibranchiata. Cephalopods with two gills and either 
eight or ten arms; shell, when present, concealed in the mantle. 
Ex. Loligo. 
