128 
JOUKNAL OF MAMMALOGY 
but quite aside from this the very fact that cetaceans may live twenty 
minutes or more without direct access to air is in itself a most remarkable 
condition and shows how highly specialized these creatures are as 
compared with their near relatives the terrestrial mammals. 
In addition to the cetaceans the seals and especially the sea-cows 
or sirenians are mammals that lead an aquatic existence. In fact it 
is probable that the sea-cows, like the cetaceans, never come upon land 
at all, but remain always in the water. They inhabit the shallow 
seas of the warmer regions and are common about the mouths of 
rivers which they ascend for considerable distances. They are inof- 
fensive quiet creatures feeding upon sea-weeds and other aquatic 
plants. The east coast of Florida is inhabited by a single species, 
Trichechus latirostris (Harlan), which can often be seen in the waters 
of Biscayne Bay near Miami. It was during my sojourn at the labo- 
ratory of the Miami Aquarium Association, at Miami Beach, Florida, 
that I had the opportunity of studying three of these animals which 
were contained in a large outside basin on the grounds of the aquarium. 
I am indebted to the officers of the Miami Aquarium Association for 
the opportunity I there had of observing the habits of these sea-cows, 
especially their respiration, under conditions that were as near natural 
as possible. 
The three sea-cows or manatees, as they are commonly called, had 
been confined in the aquarium nearly a year. In the course of that 
time they had become extremely tame and lived a life of sluggishness 
much as they do in nature. They fed freely on cabbage leaves and 
appeared in all respects to be in excellent condition. After a full meal 
they would lie quietly in the water often for hours at a time, their 
apparent repose being interrupted only by an occasional rising to the 
surface for air. As is well known they rest under water in a curved 
position with the head and tail depressed and the back arched up and 
near the surface. .When they rise to breathe, the back usually breaks 
the surface of the water first, after which the head emerges. Expiration 
and inspiration are then quickly accomplished whereupon the animal 
slowly sinks again below the surface of the water. Two or three such 
respiratory acts commonly occur, one quickly following the other, 
after which the manatee sinks into the water to remain quietly there 
for a considerable period. These operations are carried out with slow- 
ness and regularity so that it is comparatively easy with a watch in 
hand to take complete records of as many as three animals at one time. 
