PORPOISES AND DOLPHINS. 
53 
a mile from the ship. The whale was a tinner, or humpback, of no very great size, 
and was seen spouting, and again descending. Immediately after its first descent 
there appeared above the surface of the sea what seemed to be the tail-fin of some 
animal unknown. This supposed fin was raised in a vertical position, where it 
remained vibrating for some seconds and then suddenly disappeared. In colour 
it was a pure glistening white; while in form it appeared to be laterally com¬ 
pressed, with sharp edges and an acute termination. It gave the impression of 
belonging to some animal which was engaged in attacking the whale beneath the 
surface; and I should estimate its height above the water approximately at 5 or 6 
feet. Soon after the disappearance of this strange white object, the broad black 
head of what I presume to have been a killer was seen above the water; and in a 
few seconds the whale itself again rose to spout. That these black animals, which 
appeared to be harrassing and attacking the whale, were killers, I have no reason¬ 
able doubt; but the question arises as to the nature of the animal to which the 
strange white tail-like object seen standing above the water could have belonged. 
My impression at the time was that it must be the upper lobe of the tail of some 
enormous shark allied to the threshers {Alopecias) ; and this impression has been 
confirmed by a subsequent examination of the stuffed specimens of that genus in 
the British Museum. The thresher is, however, a black shark; while the minute 
size of its teeth seems to discredit the common accounts of its attacking whales. 
Unless, however, it could have been the flipper of a humpback, I am at a loss to 
imagine to what other animal the aforesaid white tail-like object could have 
belonged, save to some gigantic shark allied to the thresher, but of a white colour, 
and probably armed with much larger teeth. 
The Lesser Killer. 
Genus Pseudorca. 
An adventitious interest attaches to the Cetacean known as the lesser killer 
{Pseudorca crassidens) owing to its having been originally described on the 
evidence of a skull dug up in the Lincolnshire fens, which was for a long time 
regarded as pertaining to an extinct species. This animal is distinguished from 
the killer by its smaller back-fin, the pointed flippers, and the cylindrical roots of 
the teeth, as well as by certain features in the structure of the skull. In colour 
the lesser killer is entirely black; and it attains the length of about 14 feet. There 
are generally eight teeth in the upper jaw on each side, and ten in the lower jaw. 
This species appears to be cosmopolitan, having been met with in small herds on 
the coast of Denmark, and also in Tasmania. Its habits are probably somewhat 
similar to those of the killer. 
The Blackfish. 
Genus Globiocephalus. 
The blackfish {Globiocephalus melcis) derives its English name from its nearly 
uniform black coloration, while its generic title refers to the characteristic globular 
