508 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



grass, the materials used varying in different localities. Cotton, rags, feathers, 

 and seaweeds are also sometimes incorporated into the walls. They are placed 

 on various kinds of trees and bushes, such as oaks, pines, and willows, and at 

 various heights from.the ground, ranging from 3 to 40 feet up, and again in water- 

 myrtle bushes, canebrakes, and reeds in swamps, not over 18 inches above the 

 water level. 



The number of eggs laid to a set varies from two to five. Sets of three are 

 most common; but in certain localities sets of four are equally so, while those 

 of five are somewhat rare. 



Incubation lasts about fifteen days, and this duty seems to be mostly per- 

 formed by the female. The male, however, assists in feeding the young, and 

 after they are able to care for themselves the sexes separate in flocks and remain 

 apart until the mating season approaches again. 



The eggs of the Boat-tailed Grraekle closely resemble those of the preceding 

 species, both in shape and coloration, excepting that the cloudy purple vinaceous 

 and pale umber tints are generally more evenly distributed over the entire shell, 

 when present, and are not so noticeable at the small end of the egg. In some 

 instances the lines and tracings with which they are marked are also perceptibly 

 finer as well as more profuse, being more like the markings found in the eggs 

 of the Baltimore and Bullock's Oriole. They also average somewhat less in size. 



The average measurement of ninety-eight eggs in the United States National 

 Museum collection is 31.60 by 22.49 millimetres, or about 1.24 by 0.89 inches. 

 The largest egg measures 34.29 by 24.64 millimetres, or 1.35 by 0.97 inches; the 

 smallest, 27.94 by 21.59 millimetres, or 1.10 by 0.85 inches. 



The type specimens, Nos. 25632 and 25634 (PL 7, Figs. 30 and 31), both 

 from sets of three eggs, from the Ralph collection, were taken in Mcintosh 

 County, Georgia, on April 26 and 29, 1890, and represent the ordinary styles of 

 markings. 



