8 THE ZOOLOGIST. 
lower jaw at the same distance from the front, and are compressed 
rather than conical. 
Mesoplodon bidens (Sowerby). Sowerby’s Whale.— Average 
length from 15 to 18 feet, with 38 vertebre and 10 pairs of ribs. 
The front slopes gradually to the beak. The front slopes gradually 
to the beak; the upper jaw is shorter and narrower than the under 
one, the projecting teeth on each side of the lower jaw being visible 
externally. The dorsal fin small; flippers the same. In colour it 
is described as black above and white below, the sides marked 
with vermicular white streaks. This species was first described 
by Sowerby from a specimen 16 feet in length, which was cast 
‘ashore in Elginshire. Since then others have been taken on the 
coast of Kerry and elsewhere in lreland. Nothing is yet known 
of its distribution and habits. 
Family DELPHINIDE. 
Genus Monodon, Linnezus. 
No dorsal fin and very small flippers. Head raised, with a small 
mouth and no beak. Two teeth in the upper jaw only. These 
are rudimentary and concealed by the gum in the female, but in 
the male, one (the left) is projected forward, in the shape of a long 
straight tusk, half the length of the body.* 
Monodon monoceros, Linn. The Narwhal.—Averages 14 to 
16 feet in length, with a single straight tusk 7 or 8 feet in length, 
In colour it is grey above, mottled with black ; aud white beneath, 
spotted with grey and black. Its usual haunts are between 70° and 
80°N. lat. Three instances are on record of its occurrence on our 
coasts, namely, in Shetland, in the Firth of Forth, and near Boston, 
Lincolnshire. ‘The word “ Narwhal” signifies the Beaked Whale, 
from the Gothic nar, Icelandic ner, the beak. 
Genus Delphinapterus, Lacépéde. 
Agrees with Monodon in having no dorsal fin, small flippers, 
a small round head, and no beak; but differs from it in having 
teeth in both jaws, none of which are prolonged externally. The 
tail is broad and powerful. 
Delphinapterus leucas (Pallas). White Whale, or Beluga.— 
Attains a length of from 10 to 16 feet, and has 50 vertebre and 
* Occasionally, though rarely, both tusks are thus developed. There is a 
specimen in the Cambridge University Museum with two tusks, the left measuring 
6 feet 7 inches, the right (which has been broken) 6 feet 1 inch. 
