420 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



coverts darker and browner, narrowly tipped whitish and inner 

 webs usually mottled ash-grey ; axillaries white sometimes with 

 grey bases and some shaft-streaks ; under wing-coverts white, 

 feathers round edge of wing brown narrowly fringed white ; tail 

 black-brown, bases concealed by coverts, grey-brown ; wing- 

 feathers with outer webs and outer part of inner webs and tips 

 black-brown, rest of inner webs pale brown shading to white on 

 basal halves, inner secondaries with very narrow white tips ; 

 primary-coverts and those along edge of wing black-brown 

 with narrow pale brown tips ; rest of wing-coverts brown, but 

 terminal portions of greater pale brown and when fresh with 

 very narrow white tips. No moulting examples available for 

 examination. 



Nestling. — Down on upper-parts slate-grey, on under-parts 

 paler and on centre of breast ashy-grey. Very long, soft, and silky 

 on upper-parts, shorter on under-parts ; chin, upper -throat and 

 lores bare. N.B. — I have been unable to find any trace of two 

 downs in the examples examined. 



Juvenile. Male and female. — Like adult but feathers of rump 

 and upper tail-coverts with better defined narrow white tips and 

 with more narrow white bars, long scapulars narrowly tipped white, 

 inner primaries narrowly edged white at tips and secondaries more 

 widely tipped white, when fresh greater coverts tipped white with 

 faint subterminal line. 



Measurements and structure. — $ wing 151-167 mm., tail : 

 central pair 60-70, outermost 67-76, depth of "fork" 6-11 

 (occasionally almost square), tarsus 43-47, middle toe with claw 

 35-40, bill from feathers 17-20 (9 measured). $ wing 154-170 

 (21 measured). Primaries : 1st minute, pointed and concealed by 

 primary- coverts, 3rd longest, 2nd 8-14 mm. shorter, 4th 2-5 shorter, 

 5th 12-20 shorter, 6th 25-30 shorter. Tail slightly forked. Tarsus 

 and toes very long. Claws decidedly flat. Rest of structure as in 

 Storm -Petrel. 



Soft parts. — Bill, legs and feet black, webs yellow usually with 

 narrow margin of black but sometimes mostly yellow and edges of 

 toes yellow ; iris black-brown. 



Characters and allied forms. — P. m. marina (south Atlantic) 

 is darker on upper -parts and has shorter bill. Dark crown, white 

 eye-stripe and dark stripe on ear-coverts and white under-parts 

 •distinguish this from other small British Petrels. 



Pield- characters. — Fluttering butterfly -like flight and con- 

 spicuously contrasted colours easily distinguish this Petrel from 

 others. Larger than Leach's or Wilson's Petrels, lighter above 

 (greyish to greyish -brown) with conspicuous grey upper tail- 

 coverts, under-parts wholly white and long black legs dangling 

 over the water : feet black and orange : conspicuous white 

 frontal band and superciliary stripe. Surface feeder. Often 



