LESTRIS. 263 



Tinder-parts, are greyish black, tinted with brown 

 on the belly, and on the chin paler, nearly dark- 

 grey ; the quills and tail are black ; the greater and 

 lesser wing-covers grey, the latter tipped with 

 greyish white, which shows a pale bar across ; the 

 last rump- feathers, part of the tail-covers, and a 

 limited spot behind each thigh, white; tarsi, feet, 

 and bill, black. 



These are all the birds belonging to the Petrels 

 which have yet been found on our islands ; but it is 

 possible that others of this small race may yet have 

 been overlooked, more particularly as the real range 

 of the last has been seen to be so far distant. They, 

 with one or two allied genera, are by far the most 

 decidedly sea-living birds among the Laridse. 



Our next form also spends a great portion of its 

 time on the ocean, has a powerful flight, exhibits 

 some alliance with the last in the structure of the 

 feet, and is remarkable in pursuing the true gulls, 

 and forcing them to disgorge or quit their newly- 

 taken prey. It constitutes the 



GENUS LESTRIS, Illiger. Generic characters. 

 Bill strong, thick, compressed at the tip, co- 

 vered as far as the anterior angle of the nos- 

 trils with a horny cere ; tip of maxilla finishing 

 in a powerful hook ; mandible with a strong 

 angle, fitting into the maxilla ; nostrils lateral, 

 placed immediately behind the tip, angular, an- 

 teriorly widest, pervious ; wings long, first quill 



