TOOTHED WHALES 181 



In fact, we may still fairly accept the family, as does 

 Flower in his most recent expression of opinion,* 

 and as does Kiikenthal.t In several ways Pontoporia 

 points towards the true dolphins, the Delphinidae 

 of the present volume. The attachment of the 

 ribs is purely delphinoid, the curious double attach- 

 ment of the genera Platanista and Inia not being 

 preserved. There are also five lumbar vertebrae 

 instead of the reduced lumbar region of the genus 

 Inia. 



The prominent dorsal fin is moreover a charac- 

 teristic of the dolphins, as indeed of other groups. 



All the Odontocetes have at least a trace of the 

 elevation laterally of the maxillae ; this is carried to 

 an extraordinary pitch in the full-grown male of 

 Hyperoodon. Platanista too has a pair of thin plates 

 which arch over the front of the head at the base 

 of the snout, which are extensions of the maxillae, 

 and may be referred to the same category. This 

 genus moreover, and Inia, agrees with the Sperm 

 whales and the Ziphioids in the permanently carti- 

 laginous ribs ; in the dolphins the sternal ribs are 

 ossified. The length, both of the lower jaws them- 

 selves and of their symphysis, has led to their being 

 described as miniatures of the lower jaw of the 

 Cachalot ; in fact, there are many resemblances be- 

 tween the Platanistidae and the Physeteridae. The 

 connection of both seems to be plain. 



* In Mammals, Recent and Extinct. London, 1891. 

 t " Vergleichend-anatomische u. Entwickelungsgeschichtliche Unter- 

 suchungen an Walthieren," Denkschr. med.-nat.-Ges. Jena, 1889. 



