LABILE — STERNIN^ : TERNS. 



761 



Tomia of toth mandibles sharp and much inflected. Nasal groove long, fully half the culmen, 

 narrow, not deep, directed obliquely downward and forward toward the tomia. A few oblique 

 indistinct striae on both mandibles. The outline of the feathers on the bill is as usual. Adult in 

 summer : Bill bright red, salmon-colored toward tip. Feet black ; soles and under surfaces of 

 claws slightly yellowish. Crown of head, including long-flowing occipital crest, pure black, 

 reaching down on the sides of tlie head to a straiglit line just on a level with the lower border 

 of the eye ; the white of the cheeks accompanying the hlacli to the foremost point of extension 

 of the feathers in the nasal fossaj. All the under parts rosy-wliite, with satin gloss. Tail 

 entirely pure white, longer and more deeply forked than in winter. Back and wings pale pearl- 

 blue ; the usual pattern of coloration of the primaries. "Length 19; extent -18" (label); 

 culmen 2.75 ; gape nearly 4.50 ; depth of bill at base 0.50; gonys 1.50, not shorter than man- 

 dibular rami; wing 12.25; tail 7.50; depth of fork 3.50; tarsus 1.25; middle toe and claw 

 the same, or rather less. In winter : Bill orange, fading to yellow at tip and along catting 

 edges. Forehead and feathers on side of bill entirely white ; crown varied with dark and white, 

 black prevailing on hind head, complete on the occipital crest and sides of head to eyi'S. Ko 

 pink blush of under parts. Tail shorter than in summer, 5.00 or loss, forked only about 2.00, 

 washed over with pearly-blue. Total length less, owing to less development of tail, 16.00- 

 17-00. Young not seen. A truly elegant species, resembling the royal tern, but easily dis- 

 tinguished. S. and C. Am. to California; unknown on our Gulf or Atlantic coast. 

 196. S, (T.) canti'aca. (Of Kent, England. Fig. 515.) Saxdwich Tern. Ducal Tern. Bill 

 much longer than head, exceeding the tarsus, middle toe, and claw together ; quite slender 

 and attenuated for this sub- 

 genus, tip excessively acute ; 

 convexity of culmen, from 

 tip to base, regular, but 

 slight ; commissure gradual- 

 ly declinato-convex through- 

 out ; outhne of mandibular 

 crura decidedly concave ; that 

 of gonys about straight ; 

 eminentia symphysis hardly 

 appreciable. Adult, breed- 

 ing plumage : Bill black, ■^"*- ^'^- ~ Sandwicli Tern, nat. size. (Ad nat. del. E. C.) 

 the tip for i to i of an inch bright yellow, sharply defined against the black ; " inside of 

 mouth deep blue." Feet dull black. Pileum and occipital crest glossy black, with a tinge of 

 green; the color extending just below the eyes, but leaving a space along the side of the 

 mandible white to the extremity of the feathers. Mantle exceedingly light pearl-blue fadino- 

 on the rump and ujjper taU-coverts into pure white; but the rectrices themselves have a 

 slight shade of pearly-bluish. Primaries colored as in maxima. On the inner web of the 

 first the black space is broad and deep in color ; when about li inches from the apex of the 

 quill it quite suddenly grows \nder, so as to exclude the white portion from the tip altogether. 

 The second, third, and fourth primaries have the same general pattern, but the white runs 

 up further on the central portion than on the edge of the web, so that toward its end it 

 receives a narrow edging of blackish. The other primaries have no blackish, but are simply 

 pearl-blue, with broad white margins along the whole length of their inner webs. The outer 

 primaries are aU heavily silvered when the quills are new. Dimensions of the adult : length 

 15.00-16.00 inches; extent 34.00; wing from the carpus 12.50; tail 6.00; depth of emargi- 

 nation 2.35 ; biU along culmen 2.25 ; along gape 3.00 ; its height at base 0.48 ; width, ditto, 

 0.37; length of rami from feathers on side of lower mandible 1.00 ; gonys 1.20 (longer than 

 rami) ; tarsus 1.00 ; middle toe and claw, slightly longer. Adult, winter plumage : YeUow 



