CLASSIFICATION OF THE CETACEA 419 



3 Mesoplodon [Commonest type is Sowerby's Whale (Alesoplodon 

 bidens (Sowerby),], 13-22 ft. 9 species with fairly limited distribu- 

 tion, genus is universal. 



4 Berardius, 30 ft.-42 ft. 2 species in Atlantic part of Antarctic and 

 N. Pacific respectively: B. arnouxii Duvernoy and B. Bairdii 

 Stej neger. 



5 Tasmacetus [Tasmacetiis shepherdi Oliver]. Functioning teeth in both 

 jaws. N. Zealand. 



D EuRHiNODELPHiDAE. Miocenc. \'ery long beaks. Anterior upper jaw 

 devoid of teeth. Ai'ticulation of ribs and vertebrae as in ^iphiidae. 

 14 ft. Probably fed on fish off the bottom. 



E Hemisyntrachelidae. Miocene-Pliocene. Short break. They look 

 like Dolphins, but rib articulation as in ^iphiidae. 



F River Dolphins {Platanistidae) . Lower Miocene-Recent. Veiy long 

 and slender beaks. Lower ja\vs fused over large area. River inhabi- 

 tants. 



1 Siisu or Gangetic Dolphin [Platanista gangetica Lebeck], 8 ft. Ganges 

 and Indus. 



2 Boutu or Amazonian Dolphin [Inia geoffrensis Blainv.], 6| ft. Amazon. 



3 La Plata Dolphin [Stenodelphis {Pontoporia) blainvillei Gerv.], 5 ft. 

 Rio de la Plata. 



4 Chinese River Dolphin [Lipotes vexillifer Miller], 7 ft. Tung Ting Lake. 



G Dolphins in the wider sense {Delphinidae sensu lato). Lower Miocene 

 -Recent. Mainly fish eaters and maritime. LoAver jaws fused only at 

 the tip. 



a Acrodelphidae. Miocene. Very long beaks. 



b Delphinapteridae. Pleistocene-Recent. No clear dorsal fin. All 

 cervical vertebrae free. 



1 Beluga [Delphinapterus leucas (Pallas) ], 15 ft. Arctic. 



2 Narwhal [Monodon monoceros L.], 15^ ft. Arctic. 



c Porpoises (Phocaenidae) Miocene-Recent. Generally clear dorsal 

 fin. Some cervical vertebrae fused. Teeth spatular. No beak. 



1 Common Porpoise (U.S.A.: Harbor Porpoise) [Phocaena phocaena 

 (L.) ], 41ft. N. Atlantic. 



2 Phocaena spinipinnis, Ph. dioptrica, S. America; Ph. truei, Japan; 

 Ph. dalli, Alaska. 



3 Finless Black Porpoise {Xeomeris phocaenoides (Cuv.) ], 4 ft. E. and 

 S.E. Asia. 



