6o2 The American Naturalist [July, 
but the feeding-polyp, which lies in the centre of the under-side,, 
is hidden by the oval float in the middle of the body. 
Of all the Medusae considered, Velella is the only one which 
floats on the surface of the sea, the whole upper surface of the 
body, or that shown in the figure, being exposed to the air. 
From this fact, as well as from certain rhythmical motions made 
by Velella, it is not improbable that the respiration is in part 
aerial in this Medusa, as has been already pointed out by Dr. 
Carl Chun. To facilitate this mode of respiration, and to bring 
the air into the interior of the body, there are tubes, called tracheae' 
communicating with the cavity of the float, through which air is 
taken in and gas expelled by the movements of the body. At 
the same time there is also an abundant opportunity for aerial 
respiration through those parts of the body which are always 
exposed to the air. 
NOTES ON THE HABITS OF SOME AMBLYSTOMAS, 
AJ\ Y observations on the habits of the Amblystomas have been 
made almost wholly on the three species, A. microstomum, 
A. tigritium, and A. punctatum. These species have received 
respectively the vernacular names, small-mouthed salamander, 
tiger salamander, and spotted salamander. All three are quite 
abundant about Indianapolis, the microstomum most of all ; and 
it is this that I have been enabled to study most carefully- 
Unless otherwise noted, my remarks will refer to this species. It 
will be most convenient perhaps to begin with the life of the in- 
dividual ; first of all with those events which make provision for 
the life of the individual. 
The eggs of the small-mouthed salamander are laid very early 
in the spring, as soon as the thick ice of the winter is gone, 
or even before it is gone. During the present year I found eggs 
of this species at noon of March 3. They had probably been 
laid during the preceding night. They were attached singly 
