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JOURNAL OF MAMMALOGY 
IJ minutes, Brown (1878, p. 296) on the average 2| minutes. Crane 
(1881, p. 457) 2 to 3 minutes with a maximum of 6 minutes, Noack 
(1887, p. 296) every 2 to 3 minutes, and Townsend (1904, p. 86) 5 to 
8 minutes, a statement repeated by Gudernatsch (1908, p. 232). The 
African manatee is said by Noack (1887, p. 300) to come to the surface 
for breathing every 1| to 2 minutes. The eastern sea-cow or dugong 
has been reported upon in the same incidental way and with much 
the same range. Thus Eiippell (1834, p. 113) stated that this sea-cow 
comes to the surface every minute or so for breathing; Klunzinger 
(1878, p. 68) gives the rate as once in 10 minutes; and Semon (1896, 
p. 317) as every 3 to 5 minutes. Dexler and Freund (1906, p. 80) 
observed the breathing rate in a newly captured dugong to vary from 
17 to 65 seconds between breaths and in the imprisoned condition to 
vary from 43 to 145 seconds. Obviously these more rapid rates both 
for the manatee and for the dugong are to be ascribed to changes in 
the animal’s activity and not to irregularities of observation, for, when 
a manatee begins to swim, it at once increases its rate of breathing 
which may rise to several times a minute. It is only with really quiet 
animals that such a period as 16 minutes or more is to be observed 
and then only when the animal is very large (3 meters long, for instance) , 
conditions of observation which have rarely occurred in earlier work. 
Florida and West Indian fishermen maintain that when the native 
manatee is hunted, it will dive and remain under water fully half an 
hour. Whether this is so or not remains to be seen, but it is not impos- 
sible that submergence periods exceeding considerably those given in 
this paper may be eventually reported. 
The observations recorded in this paper show that manatees may 
remain under water much longer than diving birds or terrestrial 
mammals and that their normal periods of submergence are so consid- 
erable that they must be regarded as specially adapted to an aquatic 
life though they are obviously much less specialized in this respect 
than are the whales, porpoises, and other cetaceans. The fact that 
they bleed profusely when butchered and are what the fishermen call 
“full-blooded” is one feature in this adaptation, for their blood is 
probably their chief storage place for oxygen. 
SUMMARY 
The Florida manatee, Trichechus latirostris (Harlan), is highly 
specialized for an aquatic life. Its breathing is related to its size in 
that the larger the animal the longer it can stay under water, the 
