AQUATIC MAMMALS 



The means of aquatic locomotion mentioned above in (1) and (2), 

 together with representative vertebrates employing them, may be ar- 

 ranged as follows. 



MODES OF AQUATIC PROPULSION EMPLOYED BY VERTEBRATES 



(1) Propulsion chiefly by means of oscillations of the body and 

 base of tail. 



(a) Body fusiform 



Pisces (the majority of fish with body form as in 

 mackerel, shark etc.) 



Reptilia 



Caudata (the majority of salamanders) 

 Crocodilia (crocodiles and alligators; chiefly) 

 Ichthyosauria (of the better known, short-tailed sorts) 



Mammalia 



Insectivora (probably only Potomogale and Limnogale) 



Carnivora (Lutrinae — the river otters, chiefly) 



Sirenia 



Cetacea (exclusive of zeuglodonts of Basilosaunis type) 



{b) Body not fusiform but largely anguilliform or eel-like 

 Pisces (eels and fish of this form) 

 Reptilia 



Serpentes (all swimming snakes) 



Amblyrhynchus (marine iguanas) 



Mosasaurs 

 Mammalia 



Cetacea (only zeuglodonts of Basilosaurus type) 



(2) Propulsion by means of appendageous movements. 

 {a) Propulsion by both fore and hind limbs 



Reptilia 



Chelonia (turtles of the mud-turtle type) 



Plesiosdun/s and doubtless others 

 Mammalia 



Carnivora {Thalarctos, the polar bear) 



Pinnipedia (Odobenidae) 



Ungulata (Hippopotamidae) 



Rodentia (Hydrochoeridae) 



[12 1 



