BRIEF SKETCH OF THE TOOTHED WHALES. 89 



siders that the flukes are developed from the greatly hyper- 

 trophied integuments of the hind limbs, analogous to such as 

 are present, for instance, in the hind limbs of the eared Seals, 

 while the osseous elements have been inversely atrophied, pulled 

 forward and reduced to supports for muscles. With all respect 

 for this ingenious theory, the view of the anatomists first 

 mentioned seems most to accord with fact, as also are the 

 views of Mr. Beddard, who points out that Ichthyosaurus, as 

 shown by Prof. Ahlborn, had a heterocercal tail with the 

 vertebrae along the lower border, and yet had hind limbs. 



The anterior limbs form a pair of paddle-like organs or flippers 

 (comparable in some respects with those of the Ichthyosauria) , 

 which consist of the shortened arm, fore-arm, and hand, en- 

 veloped in tough integument. These limbs are attached to a 

 shoulder-girdle formed of a flattened scapula with a forward pro- 

 cess, the coracoid, and above it the acronicon. In the Sperm- 

 Whale the flippers are short, broad, and truncated, in the Ziphoids 

 small and ovate, in the Susu broad and truncated,* and the 

 same in certain Dolphins, such as the Narwhal and White 

 Whale (Delphinapterus), longer in the Porpoise, large and ovate 

 — nearly as broad as long — in the Killer, narrow and pointed in 

 Pseudorca, very long and narrow in the Pilot-White, of moderate 

 size, narrow, pointed, and somewhat flattened in the Dolphin. 

 These organs are used in balancing, and it may be in certain 

 instances in sounding, as in the Ca'ing Whale, and still more 

 in Megaptera, one of the Whalebone Whales, an example of 

 which the whalers endeavoured, after it was harpooned, to drive 

 on the beach at Scotscraig, near the mouth of the Tay, but it 

 sounded with its long white flippers, and turned to deep water. 



As indicated in the remarks on the tail, no traces of pos- 

 terior limbs appear externally, but a rudimentary pelvic bone 

 (ischium, though Delage considers that it represents the ilium 

 and pubes as well) exists on each side for the attachment of 

 certain muscles, except in the Susu {Platanista) , in which it is 

 absent. 



The skeleton of the Toothed Whales presents certain dis- 

 tinctions when compared with that of the Whalebone Whales, 



'■^~ See an important memoir on the manus of this form by Sir "William 

 Tmrner (Proe. Roy. Soc. Edin. vol. xxx. p. 508, with text-figs., 1910). 



