vill SYA^OPSIS. 



ORDER II. — EPHEMEROPTERA. 



Ephenieridce, 69. Slight concentration of thoracic region 

 of May-fly, 69; free motion of prothorax, 69. Mouth parts 

 nearly obliterated, 69. Structure of wings, 69, signihcance of 

 term " Ephemeroptera," 70; reason for substituting Ephemerop- 

 tera for Plectoptera, 70. Moulting, 70. Lubbock's observations 

 on Chloeon, 70. Oligoneuria rhenana, 70. Morse's observa- 

 tions, 70. Scudder's account of May-flies on one of the Gull 

 Islands of Lake Winnipeg, 71. General remarks on Epheme- 

 roptera, 71, 72. 



ORDER III. — ODON ATA. 



Favorable subject for observational work. Libelhda triinac- 

 ulata, 73. Directions for collecting and preserving dragon-flies, 

 73. Structure of head, 74; free motion of head correlated with 

 habit of catching food when flying, 75. Size and concentration 

 of thorax correlated with great powers of flight, 75. Mode of 

 breathing, 76. Structure of abdomen, 76; toothed ridges de- 

 veloped in different species as adaptations to the similar habits 

 of the insects, 76, 77. Large size of compound eyes, 77; small 

 size of antennae, 77. Mouth parts, 77, 78; carnivorous habits of 

 dragon-flies, 78. Structure and position of legs correlated with 

 peculiar habits of insect, 78, 79. Characters of the wings, 79. 

 Ovipositor, 79. Development of dragon-flies, 80. Structure of 

 larval dragon-fly, 80; simplicity of thoracic rings, 80. Mask of 

 pupa, 81, significance of term " Odonata," 82. Brehms Thierle- 

 ben, 82, Interesting habits of pupa, 82, '^t^. Respiration con- 

 nected with locomotion, %t^. Transformation of Libellida tri- 

 maculata, 84-88; time required, ^%. Comparative length of 

 life of larva, pupa, and imago, 88. Influence of surroundings 

 on structure of aquatic and terrestrial forms, %^. General re- 

 marks on the Odonata, %%y 89. Specializations of the forms of 

 this order, 89. Resemblances of the Odonata and Neuroptera, 

 89. Parallel or representative characteristics, 89. 



ORDER IV. — PLECOPTERA. 



Stone-flies, structure of body, 90. Character of wings, sig- 

 nificance of term " Plecoptera," 90. Tracheal gills of larva 



