536 LARIDJ3. 



of the symphysis of the lower mandible prominent ; fore- 

 head white, top of the head and occiput greyish-black, 

 mottled with white ; ear-coverts uniform greyish-black ; 

 back, scapulars, and tertials greyish-black, edged and 

 tipped with buff; wing-coverts ash grey, slightly margined 

 with dark grey and buf; web of the first outer primary 

 lead grey, inner web the same, with an elongated mirror of 

 greyish-white on the inner web, the shaft white, outer 

 web of the next primary light grey, inner web dark grey ; 

 upper tail-coverts very light grey ; tail-feathers ash greyj 

 each with a dark greyish-black patch near the end, but 

 tipped with white, the white broadest on the inner margin ; 

 chin, neck, breast, belly, and all the under parts pure 

 white ; axillary plumes some grey, the longest white ; legs, 

 toes, and their membranes brownish-red, interdigital mem- 

 branes deeply divided ; beak in length almost one inch ; 

 whole length of the bird ten inches ; wing from the bend 

 eight inches and three-quarters ; tarsus seven-eighths of 

 an inch; middle toe and nail one inch and one-eighth. 

 The difference in size depended on the sex. 



