ORNITHOLOGICAL CLUB. 
35 
several instances I 'found the nests floating in two and a half to 
three feet of water without the least sign of floating rushes in the 
vicinity ; in fact, there were no rushes or anything else except fine 
swamp grass growing anywhere near, and of this the nests were 
built.” 
As already stated, they build in this section (vicinity of Minne- 
apolis) in the latter part of May or early in June, usually placing 
the nest in a prairie slough or marsh bordering an open pond. The 
material used in the construction is short bits of grass and reeds 
disposed in such a manner that a neat, but loose structure is 
formed. Occasionally greater skill is displayed, longer material 
being used, which is slightly interwoven, so that the nest may even 
be removed alone without injuring it. These frail structures are 
sometimes found upon floating masses of decayed debris, and when 
so situated it is necessary, with but few exceptions, to detach a por- 
tion of this underlying bed in order to remove the nest intact. But 
they are oftener placed upon the tops of small mounds of partially 
decayed vegetable matter. These mounds, undoubtedly made by 
the Terns as foundations for their nests, are seven or eight inches 
in diameter, and rise one or two inches above the surface of the 
water. They are placed over beds of live moss, and are partly sup- 
ported by the water and partly by the moss below. It takes but a 
slight motion of the water to rock them, and they would undoubt- 
edly often go adrift were they not generally protected by the grass 
growing around them. To obtain the nest in good condition the 
hand may be inserted beneath the pile and the whole lifted up. 
The average external diameter of the nest of this Tern is aboui 
five inches ; internal diameter, three inches ; while the depth varies 
from a slight depression to three fourths of an inch or more. The 
eggs are either two or three in number, perhaps oftener three than 
two. Their ground-color varies from deep brown to greenish white. 
The markings consist of blotches, dots, etc., of various shades of 
brown. On some specimens there are a few, and on others numer- 
ous, obscure pale spots in the shell. Frequently the markings are 
nearly equally distributed over the entire surface of the egg, but 
usually are aggregated to form a wreath around the larger end. So 
far as my observations have extended, all the eggs taken from one 
nest have about the same ground-color and character of marking. 
The average measurement of fifteen eggs before me is 1.35 inches 
in length by .98 inches in width. 
