s family
are the so-called right-whales, forming the genus _Balaena_, in which
there are no folds on the throat and chest, and no back-fin; while the
cervical vertebrae are fused into a single mass. The flippers are
short and broad, with five digits; the head is very large and the
whalebone very long and narrow, highly elastic and black; while the
scapula is high, with a distinct coracoid and coronoid process. This
genus contains the well-known Greenland right-whale (_B. mysticetus_)
of the Arctic seas, the whalebone and oil of which are so much valued
in commerce, and also other whales, distinguished by having the head
somewhat smaller in proportion to the body, with shorter whalebone and
a larger number of vertebrae. These inhabit the temperate seas of both
northern and southern hemispheres, and have been divided into species
in accordance with their geographical distribution, such as _B.
biscayensis_ of the North Atlantic, _B. japonica_ of the North
Pacific, _B. australis_ of the South Atlantic, and _B. antipodarum_
and _novae-zelandiae_ of the South Pacific; but the differences
between them are so small that they may probably be regarded as races
of a single species, the black whale (_B. australis_). On the head
these whales carry a peculiar structure which is known to whalers as
the "bonnet." This is a large horny excrescence, worn into hollows
like a much-denuded piece of limestone rock, growing probably in the
neighbourhood of the blow-hole. More than one theory has been
suggested to account for its presence. One suggestion is that it
indicates the descent of whales from rhinoceros-like mammals; another
that this species of whale is in the habit of rubbing against rocks in
order to free itself from barnacles, and thus produces a kind of
corn--although why on the nose alone is not stated. Dr W.G. Ridewood,
however, considers that the structure is due to the fact that the
horny layers which are produced all over the skin are not shed on this
particular spot.

The pigmy whale (_Neobalaena marginata_) represents a genus agreeing
with the right-whales in the absence of throat-flutings, and with the
rorquals in the presence of a dorsal fin. The cervical vertebrae are
united, and there are only 43 vertebrae altogether. The flippers are
small, narrow, and with only four digits. The ribs remarkably expanded
and flattened; the scapula low and broad, wi