Bluebird, 117 Bluejay, 117 Bohn’s studies in animal behavior, 107 Boll worm, report on, 77 _Bombus_, behavior, 120 _see also_ Humble-bee Borers, wood, 77 Brackish waters of Lower Elbe, fauna, 138 Breeding habits, bark beetles, 76 birds, of North America, 109 crawfish, 108 horned dace, 63 snout beetles, 76 _Bufo lentiginosus americanus_ Le Conte, 100 Bumble-bee, see _Bombus_ _see also_ Humble-bee Burrowing bee, 134 Butterflies, biology, 118 drinking habits, 119 food plants, 77 Cactus, Arizona, insect fauna, 135 Cactus, giant, and its insect fauna, 135 insects, 135 Caithness, vegetation, 88 Caledonia Creek, N. Y., insects and animal forms, 147, 148 _Cambarus_, 113 _Cambarus affinis_, habit formation, 106 Camp cooking, 62 Camping, 57, 60, 61, 65 Capitalization, 69 Carabidæ, early stages, 73 food relations, 127 Carbohydrates, effect on resistance to lack of oxygen, 99 Carbonic acid, reaction of fish to, 118 Card-index system for records, 64 Carrion-feeding insects, 146 Castration, parasitic, in insects, 130 Catalogues of governmental publications, 65 Caterpillars, 74 reactions, 106 Cave associations, 143 Cave environment, 144, 145 Cave fauna, European, 144 origin of blind species, 144 Cave habitats, 112, 144 Cave-inhabiting bats, habits and sensory adaptations, 112 Cave life, effect on Arthropods, 101 effect on nutrition, 101 effect on sense organs, 101 Cell and its medium, chemical studies, 88 Census, bird, 59 invertebrates, 62 of four square feet, 58, 62 Centers of dispersal for beetles of North America, 145 Cerambycidæ, food habits, 72 Cestoda and Cestodaria, index to literature of, 129 Chætognatha, classification, 115 distribution vertically, 115 San Diego region, 115 _Challenger_, 23 Change, laws of, 79 Changes, in fresh-water habitats, sequence, 86 Changes, in land habitats, sequence, 86 Chemical stimulations, responses to, 97 Chemical studies on the cell and its medium, 88 Chicago, physiographic ecology, 88 Chicago region, animal communities, 134 Chinch-bug, 20 Chorology, 2 Chrysomelid beetles, evolution, 119 Chrysomelidæ, aquatic, 75 food habits, 72 Cicindela, 90 Cicindelidæ, habits, 121 life histories and larval habits, 118 Ciliary action of shell-fish, 114 Circulars of U. S. Bureau of Entomology, Index to, 73 Clams, eaten by _Fulgur_, 110 eaten by _Sycotypus_, 110 growth of the soft, 114 hard, 114 life history of the common, 114 soft, 114 Classification, 21 animal habitats, 138 genetic, 56 habitats, 139 mollusks’ habitats, 138 physiological, 21, 101, 133, 134 Climate, influence upon insects, 135 Climatic sequences, 91 Climax biotic associations, 30 Coccinellidæ, food relations, 127