312 WHALES. 



of their interspaces being nearly transverse to the axis of the skulL 

 The smaller subsidiary plates are arranged in oblique series internal 

 to the marginal ones. The base of each plate is hollow, and is 

 fixed upon a pulp developed from a vascular gum, which is attached 

 to a broad and shallow depression occupying the whole of the palatal 

 surface of the maxillary and of the anterior part of the pala- 

 tine bones, the Whale being thus, like the Echidna, an example 

 of a Mammalian animal which may be said to have palatal teeth. 

 The base of each marginal plate is the smallest of the three sides 

 of the triangle ; it is unequally imbedded in a compact sub-elastic 

 substance, which is so much deeper on the outer than on the 

 inner side, as, in the new-born Whale, to include more than one- 

 half of the outer margin of the baleen-plate. These margins, which 

 are shown at a, fig. 4, PL 7Q, are continued downwards in a 

 line dropped nearly vertically from the outer border of the jaw ; 

 the inner margin of each plate(l) slopes obliquely outwards from 

 the base to the extremity of the preceding margin ; the smaller 

 plates decrease in length to the middle line of the palate, so that 

 the form of the baleen-clad roof of the mouth is that of a trans- 

 verse arch or vault, against which the convex dorsum of the thick 

 and large tongue(2) is applied when the mouth is closed. Each 

 plate sends off from its inner and oblique margin the fringe of 

 moderately stiff but flexible hairs(3), which projects into the mouth. 



In a new-born Whale {Balana australis) in which the longitudi- 

 nal extent of the baleen-matrix was two feet three inches, I found 

 the number of the large marginal plates to which it gave origin 

 to be one hundred and ninety. The breadth of the base of each 

 of the principal plates of baleen was two inches, the length of 

 the oblique and fringed margin three inches, that of the vertical 

 external margin three inches and a half, of which two inches were 

 embedded in the elastic substance or gum. The thickness of the 

 plate at the free part of this margin is one-third of a line, and 

 the plate becomes a little thinner at the opposite or fringed margin. 

 The direction of the plates is not quite transverse at every part 

 of the series ; the inner border is turned rather forwards in the 



(1) PI. 76, fij?. 4, b. (2) PL 76, fig. 4, c. (3) PI. 76, fig. 5, c. 



