ANOMALOUS DOLPHINS 303 



of dolphins, that is to say, the single-headed ribs 

 suddenly begin, they lose their capitular attachment, 

 and have only the tubercular ; there is no fusion 

 between the two heads, as in Inia. \But other 

 examples among the Cetacea (cf. Kogia and Physeter) 

 teach us that this is not a difference of first-rate 

 importance. Burmeister states that there are four 

 ribs, i.e., four pairs with a double attachment to the 

 vertebral column. 



The scapula of this dolphin is normal in the origin 

 of the acromion, as in Cetacea generally, but not as 

 in Platanista. Four pairs of ribs appear to join the 

 sternum, of which the last pair, however, are attached 

 by a ligament only. The sternal ribs in front of this 

 seem to be ossified. Burmeister distinctly states that 

 they are. 



The skull of Pontoporia is very symmetrical as 

 compared with other dolphins. Its surface is very 

 flat not rido-ed behind the nares like that of Inia. 



O 



The palatines, moreover, do not cover the vomer, a 

 point of likeness to Inia. The symphysis of the 

 mandible is long, and the teeth are estimated by Sir 

 W. Flower to be as many as 221 in all. 



Pontoporia blainvillii, Gervais. ' k As there is, so 

 far as we know, but a single species of this dolphin- 

 like Platanistid, it is unnecessary and indeed im- 

 possible to give it a satisfactory definition. The 

 colour was stated by M. de Freminville, who brought 

 home the original skull upon which the genus and 



* Bull. Soc. Philom., 1844, p. 39. 



