PRIMARY SUBDIVISIONS OF THE CETACEANS. 125 



II. Throat longitudinally plicated. Dorsal fln developed. 



a. Dorsal fln hump-like. Pectorals very long, 



with the four digits segmented into many 

 phalanges. MEGAPTERIN.E. 



b. Dorsal fln high, erect, falcate or subfalcate. 



Pectorals moderate, with the four digits, 

 each having four to six phalanges. 



IV. BAL^NID^E Gray. 



2. LIST OF GENERA. 

 A. ZETTGLODONTIA. 



I. BASILOSAURID^E. 



Basilosaurus Harl. = Zeuglodon Owen. 



II. CYNOECID^B. 



Cynorca Cope. Colophonodon Leidy. 



Squalodon Grat. Stenodon Van Ben. 



B. DENTICETE. 



III. PLATANISTIDJE. 

 PONTOPORIIN^E. 



Pontoporia Gray. Lophocetus Cope (extinct). 



INIIN.S. 

 Inia D'Orb. 



PLATANISTIN^E. 

 ' Platanista Cuv. 



GENERA INCERT^E SEDIS. 



Tretosphys Cope (extinct). Priscodelphinus Cope (extinct). 



Zarhachis Cope (extinct). 



IV. DELPHINIDJG. 



DELPHINAPTERIN^;. 



Delphinapterus Lac., IA\\^.=Beluga Gray. Monodon Linn. 



Delphinus Linn. Pseudorca Rcinh. 



Tursiops Gerv. = Tursio Gray. Orca Gray. 



Lagenorhynchus Gray. Orcaella Gray. 



Sotalia Gray. Phoccena Gray. 



Steno Gray. Neomeris Gray. 



Leucorhamphus ~Li\]j.=Delphinap- Sagmatias Cope. 

 terus Gray (not Lac.). 



