Acipenser sturio (illus.), 162.

Acorn-barnacle (illus.), 97.

Air-bladder, 155.

Albatross, 212.

Ant-lion (illus.), 120.

Apes, 243.

Arachnida, characteristics of, 133.
Archeopteryx, 201.

191.

Alternation of generations, 35.
Altricial, 208.

Amaba (illus.), 12; structure and
habits, 12.

Amaba-like protozoa, 12.

Amphibian, development of, 174;
distribution, 178; anatomy and
habits, 179.

Ariolimax columbianus (illus.), 81.
Armadillo, 231.

Arthropods, general features of, .
93.

Ascidian (illus.), 152.
Asexual reproduction, 31.
Asterias ocracea (illus.), 141.
Astrophyton (illus.), 143.
Auk, 209.

life), 176.

Amphioxus (illus.), 157.

Amphipod (illus.), 106.

Back-swimmer, 121.

Balancers, 122.

Barnacles (illus.), 96.

Anguillula aceti (illus.), 53.

ple and complex, 18.

Bascanion constrictor (illus.), 187.

Basket-star (illus.), 141.

Bass, 166.

Animals and plants compared, 2.
Annelids, 55.

Anosia plexippus (illus.), 125.
Ant, 128; white (illus.), 120.
Anteater. 231.

Antedon (illus.), 148.
Antelope, 239,

turtle, 188.

Carp, 163.

Cat, domestic, 239; wild, 239.
Catfish, 163.

Cell (cella, a little room), 7; shape

and size, 7; typical (illus.), 8.

Centipeds (illus.), 111.
Cephalopod (illus.), 87.
Cephalothorax, 99.

Cercopithecus (illus.), 244.

Cervus canadensis (illus.), 238.

Cestode (illus.), 50.
Cete, 234.

ture, 6.

Cottontail, 233.

Courting colors, 203.

Crab, hermit (illus.), 102; cancer

(illus.), 103; rock (illus.), 104;
fiddler, 104.

Crane (illus.), 215.
Crayfish (illus.), 101.
Cricket, 118.

Crinoid (illus.), 143.
Crocodile, 190.

Crocodilia (illus.), 190.

Crotalus adamanteus (illus.), 222.

55; distribution, 59.

Echinoderms, 141; locomotor sys-
tem, 146; development of, 150.
Ecology, 1.

Eel, 163.

Egg, fertilization of, 20, 21.
Elk (illus.), 222.

Encystment of protozoa, 13.
Epialtus productus (illus.), 104.
Epidella squamula (illus.), 49.

Gasteropod (illus.), 80; anatomy and
physiology, 81.

Gastric mill (illus.), 107.

Gastrula (diminutive of gaster,
stomach), 21.

Geese, 213.

Gelasimus (illus.), 104.

Gephyrean worms (illus.), 67.

Gila monster (illus.), 193.
Glass-snake, 191.

Lizard (illus.), 185.

Lobster, 102.

Locust (illus.), 117.

Marsupialia, 231.

or bag), 232.

Muscle-cell (illus.), 7.
Muscular system, use of, 4.
Mussel, 77.

Mysis americana (illus.), 100.
Mytilus edulis (illus.), 77.

Nauplius (illus.), 99.
Nematoda (illus.), 52.
Nemertean worm (illus.), 70.
Nereis (illus.), 59.
Nerve-cell (illus.), 7.

Nettle-cell (illus.), 30.

Neuroptera, 118.

Newt (illus.), 178.

Night-hawk (illus.), 222.

Notochord, 151.

May-fly, 118.

Megaptera versabilis (illus.), 235.
Mesenteric filaments, 40.
Messmates, defined, 48.

Metamorphosis, retrograde, 99; in-

complete, 126; complete, 128.
Metazoa, defined, 11.

Mice, 233.

Millipeds (illus.), 111.

Minnow, 163.

Mite (illus.), 138.

Mole, 234.

Octopus punctatus (illus.), 87.
Oligochates, 59.

Operculum (operculum, a lid), 87.
Opossum (illus.), 231.

Opossum-shrimp (illus.), 100.
Orang-utan (illus.), 243.

Orb-weaving spider, 136.

Ornithorhynchus paradoxus (illus-

tration). 230.

Orthoptera, 117.

Ostrich (illus.), 209.

Mollusks, general characters of, 72.

Molt, of crustacea, 99, 110; of
birds, 202.

Monarch butterfly (illus.), 125.

Monkeys, 243.

Morphology, defined, 1.

Oyster, 77.

Owls, 219.

Pagurus bernhardus (illus.), 103.

Paludicolæ, 215.

Pandorina (illus.), 19.

Panther (illus.), 241.