LEACH S FORK -TAILED PETREL. 



413 



OCEANODROMA LEUCORRHOA 



333- Oceanodroma leucorrhoa leucorrhoa (Vieill.). — LEACH'S 

 FORK-TAILED PETREL. 



Procellaria lettcorhoa (corr. leucorrhoa)~Vieillot, Nouv. Diet. d'Hist. 



Nat., now. ed., xxv, p. 422 (1817— Picardy in France). 



Procellaria leachii Temminck, Man. d'Orn., sec, ed., n, p. 812 (1820— 



St. Kilda). 



Procellaria Bullockii Fleming, Hist, of Brit. An., p. 136 (1828— St Kilda). 



Cymochorea leucorrhoa (Vieillot), Yarrell, iv, p. 37 ; Oceanodroma 



leucorrhoa (Vieillot), Saunders, p. 729. 



Description. — Adult male and female. Winter and summer. — 

 Upper-parts sooty black-brown (not so black as Storm-Petrel), 

 and when freshly moulted with a slate-grey tinge varying consider- 

 ably individually and always most marked on crown ; fore -head, 

 fore-part of crown, lores, chin, and upper -throat tinged paler ashy 



Leach's Fork-tailed Petrel (Oceanodroma I. leucorrhoa), right-hand, and the Madeiran Fork-tailed 

 Petrel ( 0. castro) left-hand figure. 



slate -grey ; longest scapulars tinged grey and with narrow white 

 fringe at tip ; feathers of lower -rump with white tips and upper 

 tail-coverts white with brown or brownish shafts (especially distal 

 part) and when fresh with narrow sooty-brown tips, lower feathers 

 often with wider tips and sometimes with some brown in centre 

 (varying considerably individually) and central pair immediately 

 over tail-feathers entirely sooty black-brown or with some greyish- 

 white ; under-parts paler and browner than upper-parts and, 

 except for throat, usually without slate -grey tinge but occasionally 

 this is well marked on rest of under-parts ; a few feathers of lower- 



