CONTENTS ix 



Page 



Shrimps, Sea-Slaters, Water Wood-Louse, Mud-Shrimps, Apus, Water-Fleas, 

 Mussel-Shrimps, Barnacles ---------- 400 



King-CrabS (Xiphosura) - - - - - - 406 



CHAPTER XXXV.— ANIMAL RESPIRATION— LOWER INVERTE- 

 BRATES WHICH BREATHE IN WATER 



Segmented Worms (Annelida) — Bristle- Worms (Chaetopoda) — Scale-Worms, 



Lugworm, Head-Gills of Tube-Dwellers ; Leeches (Discophora) - - - 408 



Siphon-Worms (Gephyrea) and Wheel-Animalcules (Rotifera) - - - 410 



Moss-Polypes (Polyzoa) and Lamp-Shells (Brachiopoda) 410 



Hedgehog- SKINNED Animals or Echinoderms (Echinodermata) — Influence 

 of the Skeleton on the Development of Breathing Organs, The Relation of the 

 Water-vascular System to Breathing 411 



Zoophytes (Ccelenterata) — Breathing by External and Internal Surfaces, Special 



Arrangement in some Sea-Anemones 416 



Sponges (Porifera) and Animalcules (Protozoa) --.--. 418 



CHAPTER XXXVI.— ANIMAL RESPIRATION— BACKBONED 

 ANIMALS WHICH BREATHE IN AIR 



Nature and Development of Lungs, Aquatic Ancestry of Land Vertebrates - - 420 



The Origin of Lungs — Swim-Bladder of Fishes — Bichir, Lung-Fishes - - 421 



Amphibians (Amphibia) — Common Frog, Cascihans, Lungless Amphibians - - 422 



Reptiles (Reptilia) — Increase in Complexity, Mechanism of Breathing, Crocodiles, 



Snakes, Snake-like Lizards, Chameleons -------- 424 



Birds (Aves) — Structure of Lungs, Air-Sacs, Mechanism of Breathing - - - 426 



Mammals (Mammalia) — Structure of Lungs, Mechanism of Breathing, Cetaceans, 



Young Pouched Mammals _ - - _ 427 



CHAPTER XXXVII.— ANIMAL RESPIRATION— BACKBONELESS 

 ANIMALS WHICH BREATHE IN AIR 



Molluscs (Mollusca) — Lung-Snails and other Gastropods which breathe in air, 



Garden Snail, Black Slug, Pond-Snail, Trumpet-Snail ----- 432 



Arthropods (Arthropoda) — Peripatus, Origin of Air-tubes 434 



Centipedes and Millipedes (Myriapoda)— Shield-bearing Centipede, Imperfect 



Development of Blood-System - . - - 435 



Insects (Insecta) — Cockroach, Bees and Locusts ; Aquatic Air-breathing Insects 

 — Great Water-Beetle, Whirligig Beetles, Great Black Water-Beetle, Pond- 

 Skaters, Water- Boatmen, Water-Scorpions, Rat-tailed Maggot, Common Gnat 437 



Arachnids (Arachnida) — Scorpions, Whip-Scorpions, Spiders, Mites - - - 442 



Crustaceans (Crustacea) — Land-Crabs, Wood-Lice ------ 443 



Land Nemertines (Nemertea), Earth- Worms and Land-Leeches (Annelida), 



AND Land Planarians (Turbellaria) -------- 444 



