THE MAMMALS OF NEW JERSEY. AI 
aa. Size medium or large (10 to 80 feet), large teeth along the lower jaw 
but absent from the upper. PHYSETERIDA, (Sperm Whales.) 
aaa. Size medium (20 to 30 feet), one tooth on each side of the lower jaw, 
or teeth absent; a narrow projecting snout. 
ZIPHIIDH (Bottle-nosed Whales.) 
agaaa. Size small (5 to 15 feet), teeth numerous in both jaws, head in some 
species rounded in front, in others with a projecting snout. 
DELPHINIDA (Dolphins and Porpoises.) 
Family BALAENIDZE. 
WHALE-BOoNE WHALES. 
This family comprises all the large whales with the exception 
of the Sperm Whale, and they are generally known as Tooth- 
less Whales or Whalebone Whales. In the very early stages 
of their development small teeth are formed, but these entirely 
disappear before birth. 
The mouth of these whales is filled with thin, heavy plates 
of baleen or whalebone attached crosswise down each side of 
the roof of the mouth. The inner edges are much lacerated 
forming a sort of seive, so that when the tongue is pressed up 
against the baleen the water in the mouth is forced through and 
passes out at the lips leaving any small animals or other food 
stranded on the seive. 
There is a popular idea that water is forced out of the mouth 
through the nostril or “blow hole,” but this is an error; the 
so-called “spout” of the whale being due merely to the con- 
densation of moisture in the discharged breath, perhaps com- 
bined with some water which may be thrown up if the discharge 
begins while the head is still slightly below the surface. 
Our Whalebone Whales belong to three genera, which may be 
distinguished as follows: 
a. No fin on the back, throat not furrowed, upper jaw highly arched and 
narrow. BALAENA 
aa. Dorsal fin present, throat deeply furrowed longitudinally, upper jaw not 
arched, skull flat and broad. 
b. Back humped, flippers very long and scalloped on the edges. 
MEGAPTERA 
bb. Back not humped, flippers moderate, not scalloped. BALAENOPTERA 
