TROCELLAKinXE OCEANODROMA 467 



Genus II. OCEANODROMA. 



Type. 

 Oceanodroma, Reichenb., Av. Syst. Nat. p. Ixxxvii. 



(1849) O. furcata. 



Eesembling Procellaria, but with a slightly shorter tarsus, which 

 is equal to, or even shorter than the middle toe and claw, and with 

 a markedly forked tail. 



The members of this genus are chiefly confined to the sea of the 

 northern hemisphere ; a single example of one species only has been 

 met with in South African Seas. 



783. Oceanodroma leucorrhoa. Leach's Forked-tail Petrel. 



^-' 



Procellaria leucorrhoa, VieilL, N. Diet, d'Hist. Nat. xxv, p. 422 (1817) 



Sliclley, B. Afr. i, p. 166 (1896). 

 Thalassodroma leucorrhoa, Dresser, B. Eitr. viii, p. 497, pi. 613, fig. 2 



(1874). 

 Oceanodroma leucorrhoa, Salviit, Cat. B. M. xxv, p. 348 (1896) ; Eeiclie- 



now, Vdff. Afr. i, p. 33 (1900). 



Description. Adult. General colour sooty-black, with a leaden 

 tinge on the head and throat ; the wings and tail darker, the 

 extreme bases of the rectrices white ; lower upper tail-coverts 

 white with brown shafts and narrow margins ; below sooty- brown 

 throughout. Bill and feet black. 



Length about 8-8 ; wing 6*10 ; tail 3-20 ; culmen 0'70 ; tarsus 

 1-0 ; middle toe 0-98. 



Sexes alike ; young covered with sooty down. This bird can be 

 at once distinguished from the Stormy Petrel by its forked tail and 

 longer middle toe. 



Distribution. Though apparently rather rarer than the Storm 

 Petrel, Leach's Petrel has a wider distribution, being found through- 

 out the North Atlantic from Virginia and Greenland to Western 

 Europe, and the North Pacific from California to Japan. There 

 is an example in the British Museum from South Africa, obtained 

 by Sir A. Smith many years ago. This is the only South African 

 record, so far as I am aware. 



Subfamily II. PUFFININ^. 



Nostrils united externally, or nearly so, above the culmen ; 

 margin of the sternum uneven ; basipterygoid processes present ; 

 ambiens muscle and caeca present ; first primary the longest, or not 

 shorter than the second. 



