2 
ALLEN'S NATURALIST'S LIBRARY. 
on its posterior margin, whereas in the Skuas there is only 
one ; the toes are more or less fully webbed, but the claws are 
small and feeble, whereas in the Skuas the latter are terribly 
curved and sharp. 
The family Laridm is divided by Mr. Howard Saunders into 
three sub-families, viz., the Terns {Sterninx), the Skimmers or 
Scissor-bills {lihynchtjpime), and the Gulls {Lanuce). 1 he 
Scissor-bills are entirely tropical, and arc found ^ in South 
America, Africa, and India. 1 hey are river 1 erns, with 
a most peculiar bill, which is not only compressed like a knife- 
blade, but the lower mandible is produced far beyond the 
upper one. These Scissor bills only frequent rivers, where 
they nest on the sand-banks. 
In the compilation of the following notes on the Laridce 
I have borrowed largely from the recent writings of Mr. 
Saunders. He has so completely made the subject his own, 
having studied the group minutely for the past thirty years, 
that there seems to be little left for anyone to discover, as 
far as the description of the plumages go. I have therefore 
adopted his conclusions, and have quoted many of his notes 
on the plumage and habits. 
THE GULLS AND TERNS. FAMILY LARIDAi. 
I have already alluded to the characters which distinguish 
the Laridm from the Skuas, viz., the absence of a cere, the 
double-notched sternum, the fully webbed toes, and the feeble 
claws. The range of the family extends over the whole of the 
world. 
THE TERNS. SUB-FAMILY STERNIN-Tl. 
Although it is very difficult to say where the Terns end and 
the Gulls begin — for a large Tern is very like a small Gull — 
Mr. Saunders has given a clear definition of the characters 
which distinguish the three sub-families of the Laridce. To 
the Scissor-bills {RJiyncho pined) I have already referred, and 
their peculiar bill separates them at once. The Terns differ 
from the Gulls in the form of the bill, which is slender and 
nearly straight, the two mandibles being almost equal in length. 
The tail is slightly or distinctly forked. 
