Whalebone- Whales. il 
tympanic (fig. 1) forms an inflated shell-like bone, and thus 
corresponds to the bladder-like tympanic, or auditory bulla 
occurring in many Carnivora. Each genus of Cetaceans has a 
characteristic type of both tympanic and periotic (fig. 11), as is 
indicated by the specimens exhibited. It is often convenient to 
speak of the combined bones as tympano-petrosal. 
The most obvious distinctive characteristic 
WIENS TOES NUTS: of the Whalebone- Whales (constituting the 
suborder Mystacoceti) is that the palate is provided with plates 
of the horny substance called whalebone, or “baleen,” which act 
as a sieve to separate the food from the water taken at the same 
Hie. 1. 
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Two Views of the Right Tympanic Bone of the Greenland Whale (Balena 
mysticetus), to show the angulated form characteristic of the Right- 
Whales generally. Half natural size. 
time into the mouth. Although rudiments of teeth are present in 
the early stages of existence, they always disappear, and are never 
of use. The external openings of the nostrils are distinct from 
each other and in the form of longitudinal slits. These Whales 
differ from the Odontoceti in many osteological characters, such 
as the breast-bone, or sternum, being composed of one piece, 
and articulating with a single pair of ribs; in the two branches of 
the lower jaw arching outwards and their anterior ends meeting 
at an angle, without any bony union; and in the skull being 
symmetrical, with the nasal bones forming a roof to the nasal 
passages. 
All the Whalebone-Whales may be included in the single 
