x Contents. 



CHAPTER XVIII. 



PACK 



STRUCTURES OP SPIDERS . 366 



NEST, WEBS, AND NETS OF SPIDERS ...... 383 



DIVING WATER-SPIDER . . . . -. . . 393 



CHAPTER XIX. 



STRUCTURES OF GALL-FLIES AND APHIDES . . . . . 398 



HAWTHORN WEEVIL . . . . . .,> . . 413 



GALL-BEETLES . . ; . .. .... . . 415 



LEAF-ROLLING APHIDES . . . . .... .418 



PSEUDO-GALLS . . . . ... . . 421 



CHAPTER XX. 



ANIMAL GALLS, PRODUCED BY BREEZE-FLIES- AND SNAIL-BEETLES . 424 



GRUB PARASITE IN THE SNAIL . .* 436 



