Earthworm, alimentary canal of Fish, egg of (illus.), 79; embry-

onic stages of (illus.), 87; -louse
(illus.), 188.

Fishes, man-of-war (illus.), 175;
nest-making habits of, 264.
Fission, 9; binary, 54.
Flagella, 25.
Flagellata, 24.

Flatworm, alimentary canal of
(illus.), 70.

Flounder, development of (illus.),
100; wide-eyed (illus.), 100.
Flying fishes (illus.), 131.
Food, adaptations for securing,
125; necessary to animal life,
106.

Form, primitive, 20.

Fossil, 18.

Fresh-water animals, barriers af-
fecting, 294.
Function, 63.

Fur seal (illus.), 136.

Galapagos Islands, animals of
(illus.), 278; locusts of (illus.),
280.

Gall, giant, of white oak (illus.),
143.

Galls, insect, on leaf (illus.), 144.

Gapes, worm which causes, 60.

Eye of dragon-fly (illus.), 239; of Gastrula, 82.

jelly-fish (illus.), 238.

Gemmule, 35.

Generalization, 66.

Fauna, 296; bassalian, 305; littoral, Generation, spontaneous, 51.

306; pelagic, 304.
Faunal areas of the sea, 304.
Feeding habit of Californian wood-
pecker (illus.), 128, 129; of Mela-
nerpes formicivorus bairdii
(illus.), 128, 129; instincts of,
244.
Female, 57.

Generations, alternation of, 51.
Geographical distribution, 272.
Geometrical larva on branch (illus.),
209.

Gerrhonotus scincicauda (illus.),
204.

Giraffe (illus.), 126.
Gizzard, 71.

Grasshopper, auditory organ of Icerya and Vedalia, 121.

Gregarina polymorpha (illus.), 14. Indo-African realm, 301.

Habitat, relation of species of, 283. Instincts, altruistic, 243; classifi-

Honey-bees, hiving a swarm of Jelly-fish, eye of (illus.), 238.

Lady-fish, metamorphosis of (illus.), Marks, recognition, 22, 129, 223.

98.

Lagoon (illus.), 44.

Medusa, 41.

Megalops, 97.

Larva, 92; of butterfly pupating Melanerpes formicivorus bairdii,

(illus.), 94.

Leaf-cutting ant mimicked by tree-
hoppers (illus.), 220.
Lemur (illus.), 302.
Lemur varius (illus.), 302.
Lemurian realm, 302.

Lepas, adult and larva (illus.), 195;

metamorphosis of (illus.), 101.
Lerema accius, distribution of
(illus.), 273.

Lernæocera (illus.), 188.
Life cycle, 78.

Life, communal, 168; duration of,
101; primitive, 21; processes,
21; social, 149.

Light, influence of, on animals,

237.

Lipeureus densus (illus.), 188.

Littoral fauna, 306.

Lizard, alligator (illus.), 204.

Lizzia koellikeri, eye of (illus.),

238.

feeding habit of (illus.), 128, 129.
Membracidæ mimicking Sauba
ant (illus.), 220.
Mesoderm, 33.

Metamorphosis, 90; of Albula vul-
pes (illus.), 98; of Anosia plex-
ippus (illus.), 92; of barnacle
(illus.), 101; of butterfly (illus.),
92; of crab (illus.), 97; of in-
sects, 90; of lady-fish (illus.),
98; of Lepas (illus.), 101; of
mosquito (illus.), 93; of sea-ur-
chin (illus.), 96; of sword-fish
(illus.), 99; of toad, 94, (illus.),
95; of Xiphias gladius (illus.),
99.
Metazoa, 32.

Metridium dianthus (illus.), 43.
Micro-organism, 16.

Migration of lemming, 118; of lo-
cust, 118.
Mimickry, 218.

Locust, post-embryonic develop- Mind, 255.

ment of (illus.), 91.
Locusts of Galapagos
(illus.), 280.

Mining-bee, nest of (illus.), 160.

Islands Molt, 91.

Louse, sucking (illus.), 188.

Macropus rufus, 139.

Mad Tom (illus.), 132.

Male, 57.

Mammals, care of young of, 268.

Manatee (illus.), 277.

Monarch butterfly (illus.), 219;
mimicked by Viceroy butterfly
(illus.), 219.
Monogamy, 135.

Mosquito, auditor organ of (illus.),
235; head of (illus.), 127; meta-
morphosis of (illus.), 93; young
stages of (illus.), 147.

Man-of-war, Portuguese (illus.), Moth, cankerworm (illus.), 59.

175.

Mantis (illus.), 127.

Many-celled animal, 2.

Marine Protozoa, 15.

Mountains as barriers to distribu-

tion, 293.

Mouth parts of mosquito (illus.),

127.

Mouse-fish in gulf-weed (illus), 208.
Mt. Orizaba (illus.), 300.
Multiplication, 50; of animals,
114; simplest method of, 53;
slightly complex methods of, 54.
Murres, Pallas's (illus.). 165.
Mussel, alimentary canal of (illus.),
72.

Mutual aid, 163.

Narcine brasiliensis (illus.), 135.
Natural selection, 117.
Neotropical realm, 301.
Nerve cells, 240.
Nerve fibers, 240.

234; of grasshopper (illus.), 234;
of mosquito (illus.), 235; of mol-
lusk (illus.), 233.
Organic matter, 112.
Organs, auditory, 232; of smell,
229; of sound-making, 235; of
taste, 228; of touch, 226; spe-
cialization of, 66; vestigial, 147.
Oriole, Baltimore, nest of (illus.),
267.

Ornithotomous sutorius, nest of,
268.

Osprey Falls (illus.), 285.
Otolith, 232.

Ox, alimentary canal of (illus.) 67.
Oxygen, necessary to animal life,
107.

Pagurus (illus.), 176.
Pandorina, 26.

Nest-making habits of birds, 264;
of fishes, 264; of insects, 262;
of invertebrates, 258; of spiders,
259; of vertebrates, 264.
Nest of Baltimore oriole (illus.),
267; of beavers (illus.), 269; of
Californian bush-tit (illus.), 270;
of Cleniza californica (illus.),
261; of pocket - gopher (illus.),
271; of rufus humming - bird
(illus.), 265, 266; of tailor-bird | Papillæ, 67.
(illus.), 268; of trap-door spider | Paramecium, 9.
(illus.), 261; of turret - spider
(illus.), 262.

Nokee (illus.), 132.

Nomeus gronovii (illus.), 175.
North Temperate realm, 299.
Nuclear membrane, 3.
Nucleus, 3.

Pandorina sp. (illus.), 26.
Pandorina morum (illus.), 27.
Papilio, chrysalid of (illus.), 205.
Papilla, tactile, of skin of man
(illus.), 227.

Paramecium aurelia (illus.), 10.
Paramecium caudatum (illus.), 11.
Paramecium plutorinum (illus.),
11.

Parasite of caterpillar (illus.), 190;
relation to host, 179.

Parasites, simple structure of, 181.
Parasitism, 179; kinds of, 180.

Obelia, alimentary sac of (illus.), Parthenogenesis, 60.

69.

Esophagus, 67.

Omasum, 67.

One-celled animals, 2.

Organ, 63; auditory, of cray-fish
(illus.), 233; of cricket (illus.),

Patagonian realm, 302.

Pediculus (illus.), 188.

Pelagic fauna, 304.

Pelican, brown (illus.), 125.
Peneus, adult and larva (illus.),
195.

Perisoreus canadensis (illus.), 138. | Protective resemblance, 201.

Phrynosoma blainvillei (illus.), 131. | Protozoa, 1; colonial, 24; marine,

Polistes, parasitized by Stylops Puss moth, larva of (illus.), 216.

Polystomella strigillata (illus.), 17. Rabbit, embryonic stages of (illus.),

Planaria, alimentary canal of Realm, Arctic, 297; Australian,

Prawn, adult and larva (illus.), 195. Rectum, 68.

Praying-horse (illus.), 127.

Pressure, a condition of animal