LIFE OF FLOWER 149 



tained skulls or skeletons of nearly all the more 

 important and well-established representatives of the 

 order, the only notable deficiency being the large 

 whalebone whale from the North Pacific commonly 

 known as the grey whale, and scientifically termed 

 Rhachianectes g/aucus. It was not many years before 

 this gap was filled by the acquisition of a complete 

 skeleton of the species in question. 



In concluding this brief notice of the work accom- 

 plished by Flower on the Cetacea, an extract may be 

 made to illustrate his views with regard to the ancestry 

 and origin of the group : 



" The origin of the Cetacea," he wrote, " is at present 

 involved in much obscurity. They present no signs of 

 closer affinity to any of the lower classes of vertebrates 

 than do many other members of their own class. 

 Indeed in all that essentially distinguishes a mammal 

 from the oviparous vertebrates, whether in the osseous, 

 nervous, reproductive, or any other system, they are as 

 truly mammalian as any other group. Any supposed 

 marks of inferiority, as absence of limb-structure, of 

 hairy covering, of lachrymal apparatus, etc., are 

 obviously modifications (or degradations, as they may 

 be termed) in adaptation to their special mode of life. 

 The characters of the teeth of 'Leuglodon and other 

 extinct forms, and also of the foetal Mystacocetes, 

 clearly indicate that they have been derived from 

 mammals in which the heterodont type of dentition was 

 fully established. The steps by which a land mammal 

 may have been modified into a purely aquatic one are 

 indicated by the stages which still survive among the 

 Carnivora in the Otariidae and in the true seals. A 



