Illustrations 



Convergence of form in shark, ichthyosaur, and porpoise 

 F 



1 Swimming principles of vertebrates 



2 Swimming movements of eel and fusiform fisti 



3 Some of the smaller aquatic mammals 



4 The insectivore otter Potomogale 



5 Pinniped postures . 



6 Sirenians .... 



7 Body postures of the manati 



8 Facial postures of the manati 



9 Types of the larger whales 



10 Heads of porpoises . 



11 Some extinct, aquatic reptiles 



12 Pharyngeal region of Kogia 



13 Blow-holes of whalebone and toothed whales 



14 Skeletons of pinnipeds . 



15 Blow-hole action in a porpoise 



16 Skulls of sirenians . 



17 Skull of a toothed whale . 



18 Skull of the sperm whale 



19 Skull of a whalebone whale 



20 Skull of the right whale . 



21 Extremes of cetacean neck vertebrae 



22 Dorsal musculature of a sea-lion . 



23 Dorsal musculature of a seal . 



24 Ventral musculature of a sea-lion 



25 Ventral musculature of a seal . 



26 Panniculus carnosus musculature of aquatic mammals 



27 Lateral musculature of the narwhal 



28 Skeletons of toothed whales 



29 Skeletons of zeuglodonts . 



30 Vertebrae of a porpoise . 



31 Sterna of whales and sirenians 



32 Development of the cetacean flukes 



33 Caudal restorations of ichthyosaurs 



34 Pectoral limb bones of some aquatic reptiles . 



35 Pectoral limb bones of pinnipeds and sirenians 



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