Volume 9 - Electric Scotland

MARINE MAMMALS OF THE NORTH-EAST OF SCOTLAND 67
specimen had all the under parts white, and was black or
blackish above ;
not " white above and black beneath " as
mentioned in Mr. Lydekker's book on British mammals.
Both the adults, male and female, that I found were black
all over ;
but as proof that they are not even varietally
distinct, my young female had a good deal of white on the
sides and under parts. The male Mesoplodon had a good
many " corduroy " markings on the shoulders and belly ;
the adult female had none of these, but I think it would be
rash to say that this is a sexual difference, as the young
female had traces of these markings.
The sternum of the male had six pairs of ribs attached
to it. The sternum of the female had only five pairs, and
was differently shaped from that of the male. I do not
think, however, that this is a sexual difference, as another
sternum of a male I examined more resembled that of the
female sternum. Here, then, is another case of " individual
variation."
One marked sexual difference is
always
to be seen in
this species. The male has two large functional teeth in
the lower jaw, from which they project about 2 inches above
the gum. The female has only rudimentary ones, and these
are hidden half an inch below the surface of the gum, while
the half-grown female had 50 additional small dolphin-like
teeth present in both jaws. That is to say, there are, in
this young specimen, in addition to the two rudimentary
tusk-like teeth in the lower jaw, 17 small ones behind
them on each side, and 8 on each side of the upper jaw.
I believe a neiv genus was once founded on the presence of
similar rudimentary teeth in Mesoplodon.
It may be interesting to state that the dorsal fin of the
male was placed nearly a foot farther back than that of the
female. Is this another "individual variation"?
I have come to the conclusion that the male stranded in
1896, and the mother and young stranded in 1899, were all
members of one family. It was reported to me in 1896 that
the
stranded whale was accompanied by another, and also a
young one, both of which got away. Now as this species is
over 5 feet long when born, one would expect
it to grow 4 or
4.5 feet more in three years, say 18 inches per annum. The