FIG. 78. A MALARIAL MOSQUITO (_A. maculipennis_), MALE, STANDING ON THE WALL 91 FIG. 79. FEMALE OF SAME 91 FIG. 80. EGG OF _Anopheles_, SIDE VIEW 92 FIG. 81. EGG OF ANOPHELES, DORSAL VIEW 92 FIG. 82. ANOPHELES LARVÆ 92 FIG. 83. ANOPHELES LARVÆ 93 FIG. 84. ANOPHELES LARVA, DORSAL VIEW 93 FIG. 85. ANOPHELES PUPÆ RESTING AT SURFACE OF WATER 93 FIG. 86. SALT-MARSH MOSQUITO (_Ochlerotatus lativittatus_); MALE 98 FIG. 87. SALT-MARSH MOSQUITO (_O. lativittatus_); FEMALE 98 FIG. 88. TOP-MINNOW (_Mollienisia latipinna_) 99 FIG. 89. DRAGON-FLIES 99 FIG. 90. THE YOUNG (NYMPH) OF A DRAGON-FLY 100 FIG. 91. THE CAST SKIN (_exuvæ_) OF A DRAGON-FLY NYMPH 100 FIG. 92. DIVING-BEETLES AND BACK-SWIMMERS 101 FIG. 93. KILLIFISH (_Fundulus heteroliatus_) 102 FIG. 94. STICKLEBACK (_Apeltes quadracus_) 102 FIG. 95. AN OLD WATERING-TROUGH, AN EXCELLENT BREEDING-PLACE FOR MOSQUITOES 103 FIG. 96. HORSE AND CATTLE TRACKS IN MUD FILLED WITH WATER 108 FIG. 97. A MALARIAL MOSQUITO (_Anopheles maculipennis_) MALE 108 FIG. 98. A MALARIAL MOSQUITO (_A. maculipennis_) FEMALE 109 FIG. 99. DIAGRAM TO ILLUSTRATE THE LIFE-HISTORY OF THE MALARIAL PARASITE 110 FIG. 100. MALARIAL MOSQUITO (_A. maculipennis_) ON THE WALL 111 FIG. 101. MALARIAL MOSQUITO (_A. maculipennis_) STANDING ON A TABLE 111 FIG. 102. SALT-MARSH MOSQUITO (_O. lativittatus_) STANDING ON A TABLE 118 FIG. 103. ANOPHELES HANGING FROM THE CEILING 118 FIG. 104. YELLOW FEVER MOSQUITO (_Stegomyia calopus_) 122 FIG. 105. RAT-FLEA (_Læmopsylla cheopis_); MALE 152 FIG. 106. RAT-FLEA (_L. cheopis_); FEMALE 152 FIG. 107. HEAD OF RAT-FLEA SHOWING MOUTH-PARTS 153 FIG. 108. HUMAN-FLEA (_Pulex irritans_); MALE 153 FIG. 109. HUMAN-FLEA (_P. irritans_); FEMALE 156 FIG. 110. MOUSE-FLEA (_Ctenopsyllus musculi_); FEMALE 156 FIG. 111. TRYPANOSOMA GAMBIENSE 164