LEAST TERN. 179 
fore-neck and lower parts, pure white ; back and wings very pale bluish- 
grey ; first two quills with the outer web greyish-black, and rather 
less than half of thei* intier web of the same colour, the rest white, 
extending to about half an inch from their extremities. Tail white 
in summer, of a paler tint than the back at other times. 
Length to end of tail 8} inches, to end of wings 94, to end of claws 
73, to end of shortest tail-feathers 7; extent of wings 183; wing from 
flexure 611; tail 34; bill along the ridge 73 twelfths, along the edge 
of lower mandible 1,°,; tarsus 74; middle toe {4,, its claw 7. 
The Female is alittle smaller than the male, but otherwise similar. 
Young fledged. Plate CCCXIX. Fig. 2. 
Bill greenish-black. Irisdusky. Feet pale yellowish-orange. All 
the under parts dull greyish-white, as are the upper parts including 
the tail; the hind part of the head streaked with dusky, on the back 
and rump the feathers with a curved marginal band of greyish-brown ; 
primary quills greyish-brown, the outer two darker. At this period the 
tail is even, each feather narrowly margined with greyish-white. 
In a male bird the tongue is 10 twelfths long, slender, triangular, 
tapering to a point, horny beneath, emarginate and papillate at the 
base. On the palate are five longitudinal ridges. The posterior aper- 
ture of the nares is linear, 7 twelfths long. The cesophagus is 4 inches 
2 twelfths long, very wide, its average diameter on the neck 43 twelfths, 
within the thorax 9 twelfths; it is exceedingly thin and delicate, its 
muscular fibres scarcely apparent, unless closely examined. ‘The pro- 
ventriculus is only a quarter of an inch long. The stomach is 9 
twelfths long, 8 twelfths broad, its lateral muscles of considerable size, 
the cuticular lining dense, tough, longitudinally rugous, and of a red- 
dish-brown colour, as in gulls. Contents of stomach and cesophagus, 
small fishes, one of them 2 inches long. The intestine is 14 inches 
long, its diameter 13 twelfths. The cceca are 2 twelfths long, nearly 
1 twelfth in diameter. 
The trachea is 2 inches and 4 twelfths long, its diameter 2 twelfths 
at the top, diminishing to 1 twelfth; its rings about 105, unossified ; 
its lateral muscles moderate, as are the sterno-tracheal, and single pair 
of inferior laryngeal. The bronchial half-rings about 25. 
mM 2 
