Translation 2783

• 166
with . a deep.notch in the centre. The head constitutes from one-quarter
to one-third of the body length. The upper jaw is•arch-shaped. .The •
lips of tha lower jaw are long, trapezoidal . or arch-shapod,• and over :-
lap the upper jaw when the moutn is closed.
The daric. elastic plates
of baleen are more than 1.5 metres long, and their width is from one
tenth to one-eighth of their length.
This subfamily con tains two gonera, Lalaena (with one species)
and inbalaena (with one species).
. . . .
Genus Dalaena L., 1758 (row-head !hale)
This genus contains a single.species. -
Bow-head Whale (Balaena mysticetus h., 1758)
This is an unusually massive whale (Pig. 42). -
The girth of
the body in its thickest part (slightly to the rear of the flippers)
is up to two-thirds of the body.length;
The makimuM length does not
usually exceed 18 metres, and very rarely is it as much as 21)fietres.
PIIC. 42. ri lMaI..clefl 1$L1'.
Fig. 42. Bow-head whale.
•
Adult waales are usually black, and jUveniles are of a greyish
dark-blue.colour. bometimes white scars can be observed on the ventral
side. Albinos (partial or complete) are occasionally reported.
Wlen the wilale is on the surface of the water a.small cervical
constrjction is seen more clearly.
A blowhole is located au the hiEhest
point of the head, and consists of two nasal orifices side by side.
The spout consists of twoj.-mst jets, is in the form of fine spray,
and reaches a height or four Or five metres.
• The hLad of an adult occupies one-third of the body Ungth.
The snout has no projections.
he oral cavity is narrow OWL high.
.1211.ere are 'altoi;ether up to 500 or 350 plates in - .eacn row, nanging from
the arch-shaped upper jaw; te larest*of them are from ;() -Lc) 5.5
moLrcs . lon . , ant. in rare .orloos 4.5 detres .. irine in finù and
long olp to 50 or GO cm). The lips of the lowùr jaw uo not have