INTRODUCTION. 21 
Order 2. Alallophaga (Bird-lice). 
Order 3. ZYhysanura (Springtails). 
Order 4. Hemiptera. — Ex. Plant - lice (Aphides), Field - bug 
(Pentatoma), Cochineal Insects (Coccus). 
Order 5. Orthoptera.—Ex. Locusts (Acrydium), Grasshoppers 
(Gryllus), Crickets (Achetina), Cockroach (Blatta). 
Order 6. Meuroptera.—Ex. White Ants (Termes), Dragon-flies 
(Libellulidze), May-flies (Ephemeridz), 
Order 7. Aphaniptera.—Ex. Fleas (Pulex). 
Order 8. Diptera. — Ex. Gnats (Culex), Crane-flies (Tipula), 
House-flies and Flesh-flies (Musca). 
Order 9. Lepidoptera (Butterflies and Moths). 
Order 10. Hymenoptera. — Ex. Bees (Apidze), Humble - bees 
(Bombidze), Wasps (Vespidz), Ants (Formicidz), 
Saw-flies (Tenthredinide),. 
Order 11. Strepsiptera.—Ex. Stylops. 
Order 12. Coleoptera (Beetles). 
SUB-KINGDOM V.—MOLLUSCA. 
Animal soft-bodied, generally with a hard covering or shell. Ner- 
vous system consisting of a single ganglion or of scattered pairs of 
ganglia. A distinct heart and breathing-organ, or neither. 
The Mollusca may be divided into the two following primary 
divisions, containing the following classes :— 
A. MoLiuscorpA.—Nervous system consisting of a single ganglion 
or of a principal pair of ganglia. -No heart, or an imperfect one. 
CLAss I, PoLyzoa.—Animal always forming compound growths or 
colonies. No heart. The mouth of each zooid sur- 
rounded by a circle or crescent of ciliated tentacles.— 
£x. Sea-mats (Flustra), Lace-coral (Fenestella). 
Crass II, Tunicata,—Animal simple or compound, enclosed in a 
leathery or gristly case. An imperfect heart.—Zx. 
Sea-squirts (Ascidia). 
Crass III. Bracutopopa.—Animal always simple; the body en- 
closed in a bivalve shell. Mouth furnished with two 
long fringed processes or ‘‘arms.”—Zx, Lamp-shells 
(Terebratula). 
B, MoLiusca Proper.—Nervous system consisting of three princi- 
pal pairs of ganglia. Heart well developed, consisting 
of at least two chambers. 
CLAss IV, LAMELLIBRANCHIATA (Bivalve Shell-fish).—No distinct 
head ; no teeth. Body enclosed in a shell which is 
** bivalve,” or composed of two distinct pieces. One 
or two leaf-lke gills on each side of the body.—£x. 
Oyster (Ostrea), Scallop (Pecten), Mussel (Mytilus). 
CLAss V. GASTEROPODA. — A distinct head and toothed tongue. 
