GUIDE TO WHALES, PORPOISKS, AND 
DOLPHINS (ORDER CETACKA). 
Wuatss, Porpoises, and Dolphins form a large group of Mammals 
specially modified for the needs of an aquatic existence, having 
no external traces of hind-limbs, the fore-limbs in the form 
of paddles, the tail expanded into a horizontal fin, or “ flukes,” 
and the nostrils situated on the top of the head, generally remote 
from the muzzle, and opening by a single or double “ blow-hole.” 
Although some of the Dolphins frequently ascend tidal rivers, 
while a few are exclusively fluviatile, the majority of Cetaceans 
are inhabitants of the open sea, and all subsist on animal 
substances. Existing Cetacea may be divided into two suborders, 
namely, the Wha'ebone Whales, or Mystacoceti, in which 
functional teeth are wanting and the upper jaw is furnished 
with whalebone or “baleen’’; and the Toothed Whales, or 
Odontoceti, in which teeth are present, although these may be 
reduced to a single pair in the lower jaw. Whales and Dolphins 
appear to be derived from primitive Carnivorous Mammals, as the 
extinct Zeuglodonts certainly have such an origin, and there is a 
strong probability that they are related to the ancestors of the existing 
Cetacea. The order includes the largest of all living animals. 
In accordance with their fish-like mode of life, 
oo the body of Whales and Dolphins is spindle- 
Whales. shaped, the head passing imperceptibly into the 
trunk without the intervention of a distinct neck, 
while posteriorly the trunk gradually tapers towards the extremity 
of the tail, which is expanded into the aforesaid horizontal flukes, 
which forms a triangular propelling instrument, deeply notched on 
its hind border. 
