1886.) The Mammary Gland of the Elephant. 927 
ing plough, which cut deeply but not so extensively as the over- 
riding mass. In the more elevated tracts, therefore, the lower 
portion often lay in grooves like cu/s-de-sac, and many of these 
exist to-day, connected with the main channels often by reversed 
or indirect drainage. The /ower limit of exportation, which de- 
fines the line of junction of the two layers, follows nearly the 
contour of 11,000 feet above sea-level (varying from 10,500 feet 
to 11,500 feet). The side-gulches, except where eroded by more 
recent aqueous action, commonly join the main cafions on this 
grade. The “timber-line” is fairly continuous with these de- 
bouchures, and I am satisfied that this feature has been largely 
instrumental in determining that sharp line of demarkation. Un- 
doubtedly the melting of the ice in the cañons left many side- 
- glaciers discharging by “ ice-falls ” over the walls for a long time 
q afterwards, the vegetation growing up to this lintit, because the 
land-locked cafions were for a period filled with water which 
arranged more or less of soil aiong the sides of the channels. 
q This fact is clearly proven by the occurrence of terraces, in such 
= lacustrine material, up to a height of 1000 feet above the present 
= Stream ‘beds in places. The positions of scattered boulders in 
the cafions, and of those imbedded in the deposits along the 
4 Walls afford further evidence of the local transportation of mate- 
rial by floating masses of ice, which dropped their burdens upon 
melti 
2 The drift of the Rocky mountains thus possesses peculiar in- 
terest, corroborating the notion of its intimate relation to the — 
‘Slacial deposits of the east, and yet exhibiting a variety in detail 
which may aid materially in unraveling obscure points in the his- 
“ tory of other areas with weak development of the same condi- 
tons, The loca! character of the effects has prevented many 
from appreciating the really gigantic erosion and deposition 
_ Which have taken place. 
: Ae 
_ THE MAMMARY GLAND OF THE ELEPHANT. 
BY SPENCER TROTTER, M.D. 
2 in this way gain an idea of the animal’s place in life, its relations 
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1c aywtend and we , Mears Se oppress eng eae i i 1 
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tothe €nvironment and to the other beings among which it lives. z 
our studies ire J pA S 8 
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a studying any particular animal form we are wont to refer” i 
` to some other well-known type as a basis for comparison, and £ 
