WHALES, PAST AND PRESENT. 201 



see in animal structures. Although appearing at first sight an entirely- 

 distinct and special formation, it evidently consists of nothing more 

 than the highly modified papillae of the lining membrane of the mouth, 

 with an excessive and cornified epithelial development. 



The bony palate of all mammals is covered with a closely-adhering 

 layer of fibro-vascular tissue, the surface of which is protected by a 

 coating of non-vascular epithelium, the former exactly corresponding 

 to the derm or true skin, and the latter to the epiderm of the external 

 surface of the body. Sometimes this membrane is perfectly smooth, 

 but it is more often raised into ridges, which run in a direction trans- 

 verse to the axis of the head, and are curved with the concavity back- 

 ward ; the- ridges, moreover, do not extend across the middle line, being 

 interrupted by a median depression or raphe. Indications of these 

 ridges are clearly seen in the human palate, but they attain their great- 

 est development in the Ungulata. 



Though the early stages by which whalebone has been modified 

 from more simple palate structures are lost to our sight, the conditions 

 in which it now exists in different species of whales show very marked 

 varieties of progress, from a simple, comparatively rudimental and im- 

 perfect condition, to what is perhaps the most wonderful example of 

 mechanical adaptation to purpose known in any organic structure. 



In the rorquals or fin-whales (genus Balcenopterd), found in almost 

 ail seas, the largest blades in an animal of seventy feet in length do not 

 exceed two feet in length, including their hairy terminations ; they are 

 in most species of a pale horn color, and their structure is coarse and 

 inelastic, separating into thick, stiff fibers, so that they are of no value 

 for the ordinary purposes to which whalebone is applied in the arts. 

 These animals feed on fish of considerable size, from herrings up to 

 cod, and for foraging among shoals of these creatures the construction 

 of their mouth and the structure of their baleen are evidently sufficient. 

 This is the type of the earliest known extinct forms of whales, and it 

 has continued to exist, with several slight modifications, to this day, 

 because it has fulfilled one purpose in the economy of Nature. Other 

 purposes for which it was not sufficient have been supplied by gradual 

 changes taking place, some of the stages of which are seen in the inter- 

 mediate conditions still exhibited in the Megaptera and the Atlantic 

 and southern right whales. 



In the Greenland right whale of the circumpolar seas, the Bow- 

 head of the American whalers {Balcena mysticetus), all the peculiari- 

 ties which distinguish the head and mouth of the whales from other 

 mammals have attained their greatest development. The head is of 

 enormous size, exceeding one third of the whole length of the creat- 

 ure. The cavity of the mouth is actually larger than that of the body, 

 thorax, and abdomen together. The upper jaw is very narrow, but 

 greatly arched from before backward, to increase the height of the 

 cavity and allow for the great length of the baleen ; the enormous rami 



