354 WHALEBONE CHAP. 
a small Rorqual. But even these are larger than the majority 
of Toothed Whales. 
The most characteristic feature by which the Whalebone 
Whales are to be distinguished from other Whales is that which 
gives to them their name, the presence of whalebone. Whale- 
bone is a horny product of the epithelium hning the mouth, and 
is comparable to an exaggeration of the transverse ridges which 
are found in the mouths of all 
mammals upon the palate. In 
non - Cetacean mammals these 
ridges vary in depth, and are 
arranged as a rule transversely, 
but with an oblique inclination. 
This is precisely how the plates 
of baleen are disposed in the 
mouth of a Whale. Each piece 
of “ bone” is triangular in shape, 
the broader end being that of 
attachment while it narrows 
gradually ; the inner side of the 
blades is frayed out into a number 
of threads which form the strain- 
ing apparatus. The plates vary 
in length up to as great an ex- 
treme length as 13 feet, which 
occurs in the Right Whale at 
Fic. 189.—Section of upper jaw, with vines: ihe cabs WS [elneks Be 
baleen plates, of Balaenoptera. a, Daler, even white. The number 
Bone of jaw; > gum; ¢ straight of these plates in the mouth is 
edge of baleen plate; d, e, frayed 
out surface of baleen plates. (After Very great. AS many as OU 
ene) blades have been counted. They 
diminish in length towards both ends of the series. Though 
whalebone has been in use for a long period, whence the whale- 
bone came was formerly one of those things not generally 
known. 
A very prevalent notion was that the whalebone formed the 
eyelids or perhaps the eyelashes of the creature. Scaliger, com- 
menting upon Aristotle, held that the whale had “lamellae upon 
the eyebrows, which, when the head is plunged below the surface; 
were raised by the water; but when the animal raised its head 
