86 CETACEA order iv 



Prosqualodon Lydekker. Five teeth are two-rooted. P. australis Lyd. in 

 Miocene of Argentina. P. davidi Flynn in Miocene of Tasmania. 



Family 2. Physeteridae Flower. 



Skull very asymmetrical. Premaxillary and maxillary in the later forms are 

 toothless, lower jaw with a varying number of one-rooted, conical teeth. Frontals 

 rising abruptly behind the nasals and forming a transverse ridge. Orbits are small. 

 Lachrymal bones large. Lower jaw symphysis long among early forms, short among 

 later. Anterior ribs with two heads. Eecent and fossil in the Miocene, Pliocene 

 and Pleistocene of Europe, North America and Australia. 



Subfamily 1. Phtseterinae. 



Cervical vertebrae, with the exception of the atlas, fused into one. Teeth all of 

 •uniform size, originally with enamel. 



Scaldicetus du Bus (Balaenodon, Eucetus, Homoeocetus, Eiidelphis, Palaeodel- 

 phis dn Bus; Hoplocetus,- Physodon Gerv.). Miocene and Pliocene of Europe, 

 North America and Patagonia. Three upper /. Nineteen teeth in the upper 

 jaw and twenty-four in the lower. 



Thalassocetus, Prophyseter Abel. Belgium. Placoziphius Beneden. Belgium 

 and Italy. Physeterula Beneden. Miocene of Europe. 



Physeter Linn., Kogia Gray. Recent, without upper teeth. 



Subfamily 2. Ziphiinae. 



One or two pairs of lower teeth enlarged. Atlas and axis one ; the remaining 

 cervical vertebrae are separate. 



Palaeoziphius Abel (Champsodelphis du Bus; Acrodelphis Ahel, partim). 

 Lower jaw with 14 alveoli, 1 and 7 teeth enlarged. Mioziphius Abel {Placo- 

 ziphi\LS Gerv.). The two front teeth enlarged. These two genei'a occur in 

 the Miocene of Belgium. 



Choneziphius Duvernoy ; Mesoplodon Gervais [Dioplodon Gerv. ; Belemnozi- 

 phius Huxley). Miocene and Pliocene of Europe and South Carolina and 

 Recent. Ziphius Cuv. ; Berardius Duvernoy ; and Hyperoodon Lac^p. Recent. 



Family 3. Eurhinod.elpliid.ae Abel. 



Bostrmn very long, narrow and with very long toothless premaxillary. SJadl 

 slightly convex or with transverse ridge. Upper and lower jaws with many one-rooted 

 teeth. Upper jaw thickened beneath the orbit and frontal often covered by the supra- 

 occipital. All the cervical vertebrae are distinct. Anteriw ribs have two heads. 



Eurhinodelphis du Bus (Priscodelphinus du Bus). The most abundant of 

 all whales in the Miocene of Belgium. Also in North America. 



Family 4. Acrodelphidae Abel. 



Rostrum originally long, but later foreshortened. Upper jaw often reaching to 

 the front eiul of th^e rostrum. Teeth are polyodont, heterodont and one-rooted. 



