THE NECK 



through the water the head is pressed from the front ; it is forced back- 

 ward against the cervical vertebrae, which are thereby squeezed exces- 

 sively together and pressed back against the anterior dorsal vertebrae." 



The thesis that water pressure against the head has reduced the length 

 of the neck by squeezing it between the head and the thorax hardly seems 

 sound. In the first place it is not alone the neck that has experienced the 

 sort of squeezing meant by Winge, but all vertebrae anterior to the flukes, 

 and the skull as well. In the second, if such a mechanical squeezing 

 would have had any effect this should be just the reverse of a shortening 

 of the cervical complex. According to modern concepts of morphology 

 this should rather have consisted of a narrowing of the skull and elonga- 

 tion of the neck. The whale has of necessity assumed a short neck in 

 order to fulfill certain mechanical requirements contributing to effi- 

 ciency in swimming and I seriously doubt whether water pressure, in the 

 sense referred to above, has entered into the question at all. 



Almost if not quite invariably in cetacean literature the shortness of 

 the neck is discussed as though this detail had in itself suffered reduc- 

 tion without reference to the thoracic elements, and this has resulted in 

 much misunderstanding. The cervical vertebrae have not alone been re- 

 duced, but all the vertebrae anterior to just forward of the center of the 

 thorax. In many mammals, including man and cetaceans, the lumbar 

 vertebrae are the most robust of the column. In man the centra of the 

 anterior thoracic vertebrae are progressively thinner and this, to an al- 

 most insensible degree, may be said to continue to, and culminate in, 

 the second cervical. In whales the reduction in centra length is more 

 marked anteriorly. The exact number of vertebrae involved is variable, 

 but perhaps in most sorts the fifth thoracic is the first to show really ap- 

 preciable shortening. The fourth is slightly shorter than the fifth, the 

 third than the fourth, and so on. By the same slight degree the seventh 

 cervical is slightly shorter than the first thoracic and this shortening may 

 culminate in the third or fourth cervical in such whales as have these 

 vertebrae unfused. This is but a general statement and details fre- 

 quently differ, however. In the zeuglodont Basilosaurus the neck is 

 clearly shortened, but the transition between the cervical and thoracic 

 series is not gradual. On the contrary, the last cervicals are somewhat 

 abruptly shorter than the first thoracics, and this might be an indication 

 that the cervicals are more responsive to the stimulus for shortening than 

 the thoracic vertebrae; but I believe that rather it is the result of its 

 anguilliform conformation. In some porpoises, such as Tursiops, al- 

 though the anterior thoracic vertebrae are considerably shorter than the 



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