220 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



Eggs. — Mr. Thayer's beautiful series of 18 sets, of one egg each, 

 makes an attractive display of striking variations. The eggs suggest 

 those of the Cabot's tern rather than those of the royal tern. They 

 vary in shape from ovate to elongate ovate. The ground color is very 

 light, varying from " pinkish buff " or pale " pinkish buff " to pure 

 white, with a decided tendency toward the latter. The commoner 

 types are spotted like eggs of the royal tern, but more sparingly. 

 Some are very heavily and boldly marked with great irregular 

 blotches of various shades of the darker browns, often almost black. 

 These dark markings frequently have the appearance of having been 

 washed out on the edges. One pink egg is uniformly covered with 

 small spots of very dark brown and pale shades of "violet gray." 



Another pink egg is blotched with "pale violet gray," overlaid 

 with large handsome blotches of " chestnut," " chocolate brown," 

 and "chestnut brown" — a beautiful egg. The measurements of 

 27 eggs, in various collections, average 53.5 by 38 millimeters; the 

 eggs showing the four extremes, measure 57 by 39, 55 by 40.5, and 

 51 by 35.5 millimeters. 



Plumages. — As I have never seen a specimen of the downy young 

 or any birds in the immature plumages, I can not say much in regard 

 to the sequence of plumages to maturity, but it seems reasonable to 

 assume that all the plumage changes are similar to those of the 

 closely related royal tern. 



Behavior. — I have never seen the elegant tern in life and can 

 not find anything in print regarding its habits, but probably its 

 behavior is not very different from that of the royal tern, which it 

 so closely resembles in appearance. 



Fall. — The elegant tern is another one of the Lower California 

 species, which has adopted the peculiar habit of migrating northward 

 at the close of the breeding season, wandering occasionally as far as 

 Monterey or San Francisco. 



DISTRIBUTION. 



Breeding range. — So far as known only in the Gulf of California, 

 Mexico (San Pedro Martir, and Cerralvo Islands, and near Guay- 

 mas). 



Winter range. — From central California (San Francisco Bay) 

 southward along the coast to Chile (Coquimbo Bay, Valdivia, and 

 near Valparaiso). 



Spring migration. — Returns to its breeding range in March and 

 April. Lower California, La Paz, April 12 to 27. 



Fall migration. — Southward to Peru (Callao Bay) in September. 

 Northward to California at about the same time : San Francisco Bay, 

 September 17; Monterey Bay, September 22 to October 29; Point 

 Pinos, September and October. 



