THE EXTERNAL FORM OF WHALES 33 



series than any type of reptile or fish. Now although 

 these structures are much reduced in the common 

 porpoise, they are not really absolutely limited to the 

 anterior margin of the fin as had been thought, for 



o ^> ' 



Professor Kiikenthal made the important observation 

 that here and there scattered over the general body 

 surface on the ventral as well as on the dorsal side 

 were similar, but rather more rudimentary, tubercles. 

 It thus appears a fair conclusion that we have to 

 deal here with a creature which has descended from 

 an armoured ancestor, such as an armadillo. By this 

 supposition it is of course not meant that the whales 

 are the offspring of creatures exactly like the arma- 

 dillo, or even referable to the same group of mammals 

 -the Edentata which includes that form ; it is 

 merely meant to suggest that their ancestors were as 

 completely armoured as the armadillo. Nor is this 

 mere theory. 



It seems to be an undoubted fact that a fossil 

 whale, called by Johannes Mliller Delphinopsis freyeri, 

 has its body covered in many regions with small, 

 closely-set tubercles. These tubercles are described 

 as being " harder than stone, " and they must be 

 comparable to the comparatively feeble tubercles 

 which the descendants of this whale and its allies 

 have retained to-day. 



THE BLOW HOLE 



The blow hole, or the blow holes (where there are 

 two separate orifices), of the whale, are, of course, its 

 nostrils. They are situated on the top of the head, as 



D 



