VI SYNOPSIS. 



ficial wing, 31, 32. Strigillations of insects, '^'i^ Scudder's 

 experiments, ^^. Appendages of the abdomen, 33; structure 

 of the ovipositor, ^t„ 34. Internal anatomy, 35. Muscular 

 power of insects, 37. Respiratory system, 38; tracheae of wings, 

 38, 39; Moseley's observations, 39; respiratory movements of 

 insects, 39, 40. Gradual development of wings, 41. Caution 

 against the use of theory in teaching, 42. Sexes of the locust, 

 42. Development of Calopteiius spretus, 42, 43. Direct and 

 indirect metamorphosis explained, 44; use of terms " complete " 

 and " incomplete," 44. Structure of larva, 45; moulting, 45; 

 pupa, 45; adult insect or imago, 45. 



CI^ASSIFICATIOX OF INSECTS. 



Necessity of dealing with insects systematically in order to 

 make clear the underlying principles of the classification adopted 

 in this work, 46. Insects compared with Worms and Arthropods 

 in general, 47; distinctive characters of insects, 47. Campodea 

 the type of the primitive, wingless, ancestral form, 47; geologic 

 evidence wanting, 47. Bibliography of the ancestry of insects 

 and Thysanura, 48, 49. Scudder's views on cockroaches, 49. 

 Adult characters of Lepisma appearing as transient larval stages 

 in groups of orders from II.-XL, 49. Generalized mouth parts 

 of Lepisma and Campodea, 49; biting and sucking mouth parts 

 modifications of Thysanuran type, 50. Different meanings of 

 the term "specialization," 50; a standard of reference necessary 

 to fix the meaning, 50; Thysanura the standard, 50, Primitive 

 winged insect described, 50; its affinities with Thysanura and 

 insects with Thysanuriform larvae, 50. Existing generalized 

 insects are in reality highly specialized, 50. Specialization by 

 addition, 51; consequent enlargement of the field of work, 51. 

 Specialization by reduction and narrowing of the field of work, 

 51; specialization by reduction the prevalent mode among the 

 " highest " animals, 51. Position of degraded forms in a natural 

 classification, 52; parasites, 52. Proper position of an animal 

 in a table of classification determined by its place in the evolu- 

 tion of the group, 52; Meyrick's views on lost organs, 52. 

 Generalized orders of insects or first series from I.-IX., inclusive, 



