COMMON TEEN. 639 



end, the sides convex, the edges sharp and inflexed, the tip 

 very acute. Nostrils linear, parallel, basal, pervious ; a faint 

 groove and ridge extending obliquely beyond them to the 

 edge of the mandible. Lower mandible with the angle very 

 narrow, the junction of the crura mesial, little prominent, 

 the sides erect and slightly convex, the edges sharp and 

 inflexed, the tip extremely acute. 



The eyes rather small, as are the apertures of the ears. 

 Feet very small ; tibia bare to a considerable extent ; tarsus 

 very short, slender, somewhat compressed, covered anteriorly 

 with small scutella, elsewhere with roundish scales. Hind 

 toe extremely small, the rest very slender, the third longest, 

 the fourth considerably shorter, the membranes Avith a deeply 

 concave margin. Claws rather long, arcuate, compressed, 

 acute, that of the middle toe very much larger, and having 

 the inner edge dilated. 



Plumage close, blended, soft ; the feathers broad and 

 rounded. Wings very long, narrow, pointed ; primary quills 

 very narrow, tapering, slightly incurved, the first longest ; 

 secondaries short, broad, incurved, rounded. Tail long, very 

 deeply forked, the lateral feathers attenuated, the medial 

 short and rounded ; the fork rounded. Wings about as long 

 as the tail. 



Bill coral-red, black toward the end, but with the tips 

 light yellow. Iris brown ; edge of eyelids black. Feet light 

 coral-red ; claws brownish-black. Head above, and upper 

 part of hind neck deep black, tinged with greenish-blue. 

 Sides of the head, fore neck, and all the loAver parts white, 

 with a faint tinge of greyish-blue on the breast. Back and 

 wings pale greyish-blue ; the hind part of the back, upper 

 tail-coverts, and edge of the wings white. Outer web of first 

 quill black, toward the end grey, of the next five hoary-grey, 

 as is a longitudinal band on the inner web, widening toward 

 the end ; the other quills like the back, but margined and 

 tipped with white. Tail-feathers with the inner webs white, 

 the outer grey, very pale on the middle feathers, gradually 

 deepening in tint, until on the outer it becomes blackish. 



Length to end of tail 16 inches ; extent of wings 32 ; 

 wing from flexure lOy^^ ; tail 7 ; bill along the ridge 1^, along 



