150 LIFE OF FLOWER 



further change in the same direction would produce an 

 animal somewhat resembling a dolphin ; and it has been 

 thought that this may have been the route by which the 

 Cetacean form has been developed. There are, how- 

 ever, great difficulties in the way of this view. Thus 

 if the hind-limbs had ever been developed into the very 

 efficient aquatic propelling organs they present in the 

 seals, it is not easy to imagine how they could have 

 become completely atrophied and their function trans- 

 ferred to the tail. So that, from this point of view, it is 

 more likely that whales were derived from animals with 

 long tails, which were used in swimming, eventually 

 with such effect that the hind-limbs became no longer 

 necessary. The powerful tail, with its lateral cutaneous 

 flanges, of an American species of otter (Lutra brasiliensis) 

 may give an idea of this member in the primitive Ceta- 

 ceans. But the structure of the Cetacea is, in so many 

 essential characters, so unlike that of the Carnivora, 

 that the probabilities are against these orders being 

 nearly related. Even in the skull of the Zeuglodon, 

 which has been cited as presenting a great resemblance 

 to that of a 'seal, quite as many likenesses may be traced 

 to one of the primitive Pig-like Ungulates (except in 

 the purely adaptive character of the form of the teeth) 

 while the elongated larynx, complex stomach, simple 

 liver, reproductive organs, both male and female, and 

 foetal membranes of the existing Cetacea, are far more 

 like those of that group than of the Carnivora. Indeed, 

 it appears probable that the old popular idea which 

 affixed the name of * Sea-Hog ' to the porpoise, contains 

 a larger element of truth than the speculations of many 

 accomplished zoologists of modern times. The fact 



