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 (Choetopoda) 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 - 41 1 



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, Csecilians, 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 - ... 433 



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 



