88 Gutde to Whales, Porpoises, and Dolphins. 
Risso’s Dolphin (Grampus griseus), the sole represen- 
bac aie tative of its genus, is a near ally of the Pilot-Whale, 
OfpAIN. ¢.5m which it differs by the total absence of teeth in 
the upper jaw, and the reduction of those in the lower jaw to from 
three to seven pairs, situated near the extremity. The fore part 
of the head is somewhat less rounded, and the flippers are shorter. 
This species grows to about thirteen feet in length, and is remark- 
able for its great variability in colour, although the general tint is 
a bluish grey. The skin of adult specimens frequently exhibits 
number of scratches, each showing three parallel lines: these are 
produced by the triple hooks in the suckers of a squid on which 
this Cetacean feeds. Somewhat similar marks are noticeable on 
the hide of Sowerby’s Beaked Whale, a species which also feeds 
on cuttlefish and squids. The species has been found, although 
rarely, in the North Atlantic and Mediterranean ; and is repre- 
sented by a closely allied, if not identical, form at the Cape. The 
stuffed specimen exhibited is a young female, taken in the English 
Channel in March, 1870, and purchased in 1871; plaster-casts 
of two heads are also shown on the west wall, both the gift of 
the U.S. Government. 
The common Dolphin (Delphinus delphis) is one of 
Dolphin. several closely allied small Cetaceans presenting the 
following characters. The muzzle is elongated so as 
to form a distinct beak (fig. 27), separated by a V-shaped groove 
from the fatty cushion in front of the blow-hole ; the teeth, which 
are very numerous, are small, conical, pointed, curved, and set 
close together ; they form from 40 to 60 pairs in each jaw, occupy- 
ing nearly the whole length of the beak, which is about twice as 
long as the rest of the skull; the back-fin is large and somewhat 
sickle-shaped ; and the flippers have a nearly similar curvature, 
and are relatively narrow. Internally the flippers have the bones 
of the second and third digits well developed, but those of the 
others rudimentary. Dolphins, like Porpoises, associate in shoals, 
and display remarkable agility and grace in their movements. 
Their food is chiefly fish, and they are not unfrequently captured 
in mackerel and herring nets. In their type of colouring they 
recall mackerel and other fishes which swim near the surface. The 
mounted specimen exhibited was taken off Mevagissey, Cornwall, 
and purchased in 1886 ; in addition to this, casts of the heads of a 
male and a female are shown on the south wall. 
