618 LARID^l. 



egg, as figured by Thienemann, is of a pale green colour, 

 spotted with ash-grey and dark reddish brown ; the 

 measurements are two inches in length, by one inch and 

 five lines in breadth. 



In the adult bird the base of the bill including the cere, is 

 dark greenish-brown, the horny, curved point black ; irides 

 brown ; all the upper part of the head black ; sides and 

 back of the neck white, tinged with straw yellow ; back, 

 tertials, wing, and tail-coverts brownish-grey; primaries 

 and tail-feathers almost black ; chin, throat, and upper 

 part of belly white ; lower part of the belly, the vent, and 

 under tail-coverts light brownish-grey ; legs, toes, and 

 their membranes black : the tarsi still bearing some traces 

 of their previous yellow colour. 



The whole length of the specimen described, from the 

 point of the beak to the end of the tail-feather next the 

 central pair, thirteen inches and a half, the central feathers 

 extending nine inches beyond ; the wing from the anterior 

 bend to the end of the longest quill-feather, twelve inches ; 

 the tarsus one inch and a half; the middle toe and the 

 claw rather shorter, or one inch and three-eighths. 



Independently of the difference in measurements, adult 

 birds of this species, compared with old ones of the species 

 previously described, have the head always much darker in 

 colour, while the back is lighter. 



The fifth European species of Lestris which I have 

 referred to, is that noticed by Dr. Richardson in his Fauna 

 Boreali-Americana, page 432, under the name Stercora- 

 rius ceppJius of Leach. Two examples from Hecla Bay 

 and Spitzbergen are in the collection at the British 

 Museum, and I possess one brought home from the Green- 

 land seas. It is at once to be distinguished by the great 

 comparative breadth of the bill at its base. 



