xv ORGANS OF SENSE 213 



persist throughcmt the life of the animal ; more often they are 

 only found in the young or even the foetal state. In some 

 species they have not been detected at any age. 



Eschricht and Eeinhardt counted in a new-born Greenland 

 right whale (Balcena mysticetus) sixty -six hairs near the 

 extremity of the upper jaw, and about fifty on each side of 

 the lower lip, as well as a few around the blowholes, where 

 they have also been seen in Megaptera longimana and 

 Balcenoptera rostrata. In a large rorqual (Balcenoptera 

 musculus), quite adult and sixty-seven feet in length, stranded 

 in Pevensey Bay in 1865, there were twenty -five white, 

 straight, stiff hairs about half an inch in length, scattered 

 somewhat irregularly on each side of the vertical ridge in 

 which the chin terminated, extending over a space of nine 

 inches in height and two and a half inches in breadth. The 

 existence of these rudimentary hairs must have some signifi- 

 cance beyond any possible utility they may be to the animal. 

 Perhaps some better explanation may ultimately be found for 

 them, but it must be admitted that they are extremely 

 suggestive that we have here a case of heredity or conforma- 

 tion to a type of ancestor with a full hairy clothing, just on 

 the point of yielding to complete adaptation to the conditions 

 in which whales now dwell. 



In the organs of the senses the Cetacea exhibit some 

 remarkable adaptive modifications of structures essentially 

 formed on the Mammalian type, and not on that characteristic 

 of the truly aquatic Vertebrates, the fishes, which, if function 

 were the only factor in the production of structure, they 

 might be supposed to resemble. 



The modifications of the organs of sight do not so much 

 affect the eyeball as the accessory apparatus. To an animal 

 whose surface is always bathed with fluid, the complex 

 arrangement which mammals generally possess for keeping 

 the surface of the transparent cornea moist and protected, the 

 movable lids, the nictitating membrane, the lachrymal gland, 

 and the arrangements for collecting and removing the super- 

 fluous tears when they have served their function, cannot be 

 needed, and hence we find these parts in a most rudimentary 

 condition or altogether absent. In the same way the organ 



