190 NORTH AMERICAN BIRDS. 



It would be impossible to describe with any degree of preciseiiess the innu- 

 merable variations in size, shape, ground-color, or shades of markings, these 

 eggs present. They all have a certain nameless phase of resemblance, and 

 may be readily distinguished from any other eggs except those of their kin- 

 dred. There are, however, certain shades of wine-colored markings in the 

 eggs of the Fish Hawk of Europe, and also in that of Australia, that 1 have 

 never noticed in any eggs of the American bird; but that this peculiarity 

 is universal I am not able to say. The smallest egg of the carolinensis meas- 

 ures 2.0I by 1.62 inches ; the largest, 2.56 by 1.88. 



The European egg is smaller tlian the American, is often, but not always, 

 more spherical, and is less i)ointed at the smaller end. Among its varieties 

 is one which is cpiite common, and is very different from any 1 have ever 

 observed among at least live hundred specimens of the American which I 

 have examined. 



An Osprey's egg in my collection, taken near Aarhuus, in Denmark, by 

 Eev. H. B. Tristram, of Castle Eden, England, measures only 2.12 inches in 

 length, — shorter by a fourth of an inch than the smallest American, — in 

 breadth 1.62 inches ; its ground-color is a rich cream, with a slight tinge of 

 claret, and it is marked over its whole surface with large blotches of a beau- 

 tifully deep shade of chocolate. 



In their habits the European and the American birds seem to present 

 other decided differences. The American is a very social bird, often living 

 in large communities during the breeding-season. The European is found 

 almost invariably in solitary pairs, and frequents fresh water almost exclu- 

 sively. The American, though found also on large rivers and lakes, is much 

 the most abundant on the sea-shore. The European bird rarely builds on 

 trees, the American almost always. The latter rarely resorts to rocky cliffs 

 to breed, the European almost uniforndy do so. There is no instance on 

 record of the American species attacking smaller birds or inferior land ani- 

 mals with intent to feed on them. The European species is said to prey on 

 Ducks and other wild-fowl. 



Genus NAUCLERUS, Vigors. 



NaxiclcTus, ViG. 1825. (Type, Faico fiircatus, LiNX ; F. forficatus, LiNN.) 

 Elanoicks, Gray, 1848. (Same type.) 



Ge\. Char. Form swallow-like, the tail excessively lengthened and forked, and the 

 wings extremely long. Bill rather small, and narrow; commissure fiiintly sinuated; 

 upper outline of the lower mandible very convex, the depth of the mandible at the base 

 being only about half that through the middle ; gonys drooping terminally, nearly straight. 

 Side of the head densely feathered close up to the eyelids. Nostril ovoid, obliquely ver- 

 tical. Feet small, but robust ; tarsus about equal to middle toe, covered with large, very 

 irregular scales ; toes with transverse scutellaj to their base ; claws short, but strongly 

 curved; grooved beneath, their edges sharp. Second or third quill longest; first shorter 



