LARIDA. 397 
. Order GAVIA. 
This Order, which includes the Gulls and Terns (Laride) and the Skuas (Sterco- 
rariide), is in some respects allied to the Limicole, possessing many osteological 
characters in common with the latter group. There is also a great similarity in the 
colour and markings of the eggs of several species of Plovers and Terns, another 
indication of their close affinity; while the young are able to run soon after they are 
hatched, and are covered with down of a more or less variegated pattern. 
That one of the smaller Skuas (Stercorarius) visits Central America during the 
winter months may be considered certain, as Herrera* and Villadaf both record 
S. parasiticus as occurring on the lakes in the Valley of Mexico; but Mr. Howard 
Saunders thinks that the species may have been S. pomatorhinus. 
The characters of the Gavie are given by Mr. Howard Saunders in the ‘ Catalogue of 
Birds,’ and the following is a summary of them :—Palate schizognathous ; nasals schizo- 
rhinal ; basipterygoid processes absent; cervical vertebre fifteen in number; coraco- 
humeral groove distinct; furcula with hypocleidium ; hypotarsus with two grooves ; 
wing aquintocubital, with the fifth secondary wanting; ten large primaries visible, one 
minute and concealed; an aftershaft to the contour-feathers present ; spinal feather- 
tract well defined on the neck by lateral bare tracts, and forked on the upper back ; 
rectrices twelve in number; oil-gland tufted; the front toes always connected to each 
other by a web. 
The eggs are usually three in number, though four have been found occasionally ; 
they are double-spotted. 
Fam, LARIDA. 
The Laride are distinguished from the Stercorariide by the absence of a cere, 
the presence of the two notches on each side of the posterior margin of the sternum, 
and their more feeble claws. Of all the families of birds they are probably the most 
cosmopolitan, being found from the Arctic to the Antarctic Oceans, and frequently 
visiting inland waters. They are divided into three subfamilies, containing the Terns 
(Sterninee), the Skimmers (Rhynchopine), and the Gulls (Larine). 
Subfam. STERNINAL. 
Between the larger Terns and the smaller species of Gulls there is considerable 
resemblance. ‘The members of this subfamily have a more sharply pointed bill than 
the true Gulls, with paragnathous mandibles, that is to say, with these about equal in. 
* La Nat. (2) i. pp. 188, 329. + An. Mus. Mexico, i. pp. 279-280. 
