viii CONTENTS 



CHAPTER XXX. ANIMAL DEFENCES RETREAT 



Page 



MAMMALS (Mammalia) Monkeys and Baboons, Chamois, Antelopes, Rumination 

 as facilitating Retreat, Importance of Dwellings and Refuges with reference 

 to Retreat, Signalling Coloration - - 363 



BIRDS (Aves) African Ostrich, Rails, Extinction of Dodo, Flight as a means of 



Retreat, Woodpeckers, Diving Birds - 367 



REPTILES (Reptilia) Brittle Tails of Lizards, Importance of Cylindrical Shape in 



Snakes, &c. - - 370 



AMPHIBIANS (Amphibia) Wrestler Frog 371 



INVERTEBRATES Ink of Cuttle-Fishes, Detachable Foot-Region of some Land- 

 Snails, Springing Molluscs, Ants and Bombardier Beetles, Use of Suspensory 

 Threads (Spiders, Caterpillars, Slugs), Crustaceans, Sacrifice of Part of Body 

 in Annelids, Possible Origin of Segmentation - - 372 



ANIMAL RESPIRATION THE BREATH OF LIFE 



CHAPTER XXXI. ANIMAL RESPIRATION GENERAL PRIN- 

 CIPLESBREATHERS IN WATER AND BREATHERS IN AIR 



GENERAL PRINCIPLES Nature of and Necessity for Breathing or Respiration, 



Breathing by General Surface, Special Breathing Organs 376 



BREATHERS IN WATER AND BREATHERS IN AIR Process essentially the same 



in all cases, Relation between Plants and Animals as regards Breathing - - 378 



CHAPTER XXXII. ANIMAL RESPIRATION VERTEBRATES 

 THAT BREATHE IN WATER 



Nature and Development of Gill-Clefts, Their possible origin in remote ancestral 



forms - - - - - - - - - - 381 



FISHES (Pisces) AS BREATHERS IN WATER Nature of Gills, Lampreys and Hags 

 (Cyclostomata), Sharks and Rays (Elasmobranchii), Sea-Cats (Holocephali), 

 Ordinary Bony Fishes (Teleostei) 383 



PRIMITIVE VERTEBRATES (Protochordata) Lancelet, Ascidians or Tunicates, 



Acorn-headed Worms - - - 388 



CHAPTER XXXIII. ANIMAL RESPIRATION NEMERTINES 

 MOLLUSCS WHICH BREATHE IN WATER 



NEMERTINE WORMS (NEMERTEA) Some resemblance to Vertebrates - - - 391 



MOLLUSCS (Mollusca) Mail-Shells, &c. (Protomollusca); Head-Footed Molluscs 

 (Cephalopoda) Cuttle-Fish, Pearly Nautilus; Snails and Slugs (Gastropoda) 

 Ormer, Keyhole Limpet, Whelk and Purple Shell, Common Limpet, John 

 Knox's Limpet, Sea-Hare, Sea-Lemon, &c. ; Bivalve Molluscs (Lamellibranchia) 

 Mussels, Cockles, Oysters, &c. - - 391 



CHAPTER XXXIV. ANIMAL RESPIRATION JOINTED-LIMBED 

 ANIMALS WHICH BREATHE IN WATER 



CRUSTACEANS (Crustacea) Common Lobster, Freshwater Crayfish, Common 

 Prawn, Hermit -Crabs, Crabs, Mantis -Shrimps, Sand -Hoppers, Skeleton- 



