CETACEA. 



Section I. MYSTICETE (c/. p. 57). 



Mysticete, Gray, Cat. Seals %■ Whales B. M. pp. 61, 68 ; Synops. 



Whales 8,- Dolph. p. 1. 

 Mystacoceti or Balaenoidea, Flower, Trans. Zool. Soc. vi. p. 110. 



Head large, depressed. Teeth rudimentary ; they never cut the 

 gums. Palate with transverse, fringed, horny plates of baleen. 

 Nostrils separate, longitudinal. Gullet very contracted. Tympanic 

 bones simple, large, cochleate, attached to an expanding periotic 

 bone, which forms part of the skull. 



The baleen of the different Whales may be divided by its structure, 

 by its form, and by its colour. The form and structure often go 

 together. 



The baleen consists of two parts: — 1, the outer layer, called the 

 enamel coat ; and, 2, the central fibres, which form the fringe on 

 the inner edge of the blade : both are well seen in cross sections 

 under the microscope. The outer coat or enamel differs in thickness 

 in the different kinds. Thus it is very thick and forms the greater 

 part of the blade in the Greenland Whale ; and in different kinds it 

 gradually becomes thinner, until it only forms a thin coat over the 

 central fibres. The central longitudinal fibres differ in thickness 

 and in number. When they are very slender, as in the Greenland 

 Whale, they form only a single layer between the two coats of ena- 

 mel, and their produced ends make a very fine, long, flaccid fringe to 

 the inner edge of the blade. In other Whales they are very nume- 

 rous, in many series, and form a considerable part of the thickness 

 of the whalebone, and make a more or less broad and rigid fringe 

 to the blade. In some the fibres are so thick and rigid that they do 

 not droop, but form an erect ragged edge to the short and broad 

 blade, so rigid, indeed, that the fibres of this kind of whalebone are 

 used to make brushes and brooms. 



The whalebone varies in form, from being narrow, elongate, many 

 times as long as it is broad at the base, by many gradations, ac- 

 cording to the families or genera, until it is not longer than broad. 

 The longest blades have the most enamel and the finest and most 

 flaccid fibres, which, on the other hand, gradually (as it belongs to 

 different genera) become coarser and more rigid as the whalebone 

 diminishes in length compared with its breadth. 



The whalebone or baleen offers exceedingly good and permanent 

 characters for the distinction and characters of the species when 

 its structure and form and colour are properly studied. It is 

 stated that sometimes the character of the whalebone is changed by 

 its preparation, as, for example, being soaked in water for some time 

 before it is brought to this country ; but the soaking, although it may 

 slightly alter the surface and make the enamel coat rather thinner, 

 does not alter the general form or microscopic structure of the 

 blades. 



In my essay on Whales in the ' Zoology of the Erebus & Terror,' 



D 2 



