ii2 SIR WILLIAM FLOWER CHAP. 



specially modified and adapted for an aquatic life. The fore 

 limbs in the same way retain all the elements of the typical 

 mammalian limb, not only in the bones, but also in muscles no 

 longer functional, and developed in different degrees in different 

 species. The foetal teeth of the whalebone whales, the rudiments 

 of a hairy covering, and especially the organ of smell, all point in 

 the same direction. The latter is very conclusive ; it is not, as 

 in fishes, adapted to perceive odorous substances floating in the 

 water, but, as in land mammals, is only acted upon by the air as 

 it passes by in the process of respiration ; but as in this form it 

 can be of very little use to an animal passing its existence almost 

 entirely under water, it has become quite rudimentary, and in 

 many of the dolphins and porpoises all trace of it is lost. 



Among the different groups of Cetacea there are various stages 

 of perfection of the pelvic organs. In one, the Tlatamista of the 

 Ganges, there appear to be none ; in the common dolphin, 

 porpoise, etc., there are only simple styliform pelvic bones, but no 

 trace of anything that can be called a hind limb. Among the 

 large whales all have the pelvic bone, some a mere rudimentary 

 nodule of cartilage representing the femur, some with a larger 

 bony femur, some with both femur and tibia, with muscles, etc., as 

 just mentioned. 



The seals afford no help to the origin of the whales ; their 

 resemblances are analogical ; they have all complete hind limbs 

 and pelvis (though small) as in ordinary mammals. They swim 

 by their hind legs, the tail being rudimentary ; the whales swim 

 by the greatly developed tail, the hind limbs being rudimentary. 

 I do not believe that a Cetacean can be a further stage of a seal, 

 as some seem to fancy, because when an animal had obtained 

 such a perfect adaptation to its mode of life as a seal has, by 

 means of (its) hind limbs being so specially modified, it is difficult 

 to imagine their function being transferred to the tail. On the 

 other hand, it is far more likely that an aquatic animal with a large 

 tail already of some use in swimming, like a beaver or an otter, 

 might have this organ expanded and perfected, when the legs 

 would gradually cease to be of use the more exclusively aquatic 

 the animal became. There are several points about the anatomy 

 of the Cetacea which make me think they are rather allied to the 



