621 



STEENIN^. 



TERNS AND ALLIED SPECIES. 



Although there is a great affinity between Gulls and 

 Terns, the smaller species of the one group and the larger of 

 the other being very similar in form, colouring, and habits, 

 the differences which they present are as great as those 

 between several other equally allied families. The Sterninae 

 are easily recognized by their slender, elongated form ; nearly 

 straight, compressed, exceedingly attenuated bill; very di- 

 minutive feet ; and very long, narrow, acuminate wings. 



The bill is about the length of the head, straight or 

 slightly arcuate, tapering, compressed, very acutely pointed. 

 The tongue is long, slender, and pointed. The oesophagus 

 •wide ; the stomach rather small, moderately muscular, with 

 a dense, longitudinally rugous epithelium ; the intestine of 

 moderate length and Avidth, with small cceca, and a large 

 globose cloaca. 



The nostrils are direct, linear, pervious; the eyes of 

 moderate size, as are the aural apertures. The legs are 

 very small, slender, with the tibia bare to a considerable 

 extent ; the tarsus little compressed ; the hind toe very 

 small, the anterior toes rather short and slender ; their webs 

 emarginate ; the claws arcuate, compressed, acute, that of 

 the third toe proportionally large. 



The plumage is soft, of rather loose texture ; the feathers 

 broad and rounded. The wings extremely elongated ; the 

 secondary quills of moderate length or rather short ; but the 

 primaries very long, the outer tapering to a narrow point. 

 The tail various, often forked, of twelve feathers. 



White, pale bluish-grey, and black are the prevailing 



