THE AUSTRALIAN MUSEUM MAGAZINE. 



267 



The skull of the Tasmanian whale ( Prosqualodon davidisi fully restored. 

 It will be seen that the snout is much shorter than that of the Northern 

 shark-toothed dolphin, shown below. The teeth, however, are very similar. 



quite devoid of liairy covering. This 

 is only partially true. It is a fact that 

 some whales when full grown have no 

 hair of any sort, but in some of these 

 it is found that the young one develops 

 a small amount of hair which is after- 

 wards shed. Some grown-up shales 

 have hair but it is never well developed, 

 and in fact the hairs are so fe^^■ that 

 they can be quite easily counted. They 

 are always situated in the region of the 

 upper lip, forming a sort of sparse 

 '■ moustache." The structure and de- 

 velopment of these hairs shows that 

 they are quite of the same type as in 

 other mammals, and that there is not 

 the slightest doubt that they are the 

 relics of the ancestral hairy covering 

 noAv almost entirely lost. 



The flippers or paddles of a whale 

 correspond to the fore limbs of the 

 ordinary mammal, although at first 

 sight they are very different. They 

 possess bones which agree exactly A\ith 

 those found, for example, in the fore 

 limb of a dog, and these divide the 

 flipper into parts representing the 

 upper arm, the fore arm, and hand. 

 The bones, however, are so flattened 

 and brought so closely into contact 

 that the only movable joint left is at 

 the shoulder. This flipper forms a 

 very efficient balancing organ. 



Of the hind limb nothing is externally 

 visible in Avhales. Some of its bones 

 however, have been found in a de- 

 generate condition in many whales, 

 buried in the flesh in just the position 



Shark-toothed dolphins inhabited the seas of the Northern Hemisphere in past geological 



ages. This represents the skull of one of them. The snout is very long compared 



with that of the VVynyard whale, but the number of teeth is about the same. These 



teeth, fang like in front and, at the back, cutting past one another like scissor 



blades, form an ideal means for the capture and preliminary mastication 



of such slippery and active prey as fishes. 



[After O. Abel. 



