18/6.] MR. H. SAUNDERS ON THE STERCORARIIN^. 321 



the Azores, Madeira, or the Canaries ; but future observations may 

 probably show a somewhat more extended range than I have been 

 able to trace. 



As a species it is nowhere abundant, and of late years its numbers 

 in the Faroes and Shetland Islands have so seriously diminished 

 as to render its speedy extermination there extremely probable. 

 Although, like the rest of the family, it is essentially a " robber 

 guil," yet it is by no means entirely parasitic ; for it feeds to a great 

 extent upon flesh, and especially upon the Kittiwake gull, of whose 

 feathers and bones all the castings were composed which Capt. 

 Feilden examined at the Fiiroe Islands, whilst the stomachs of 

 those he shot were full of flesh. This purely maritime Gull is the 

 only one which can be plundered with impunity that is found in any 

 great numbers in the haunts of the Great Skua ; for the Herring- and 

 Great Black-backed Gulls would not tamely yield their prey; and it 

 is worthy of note that the winter range of S. catarrhactes extends 

 no further south than that of the Kittiwake. We shall see that the 

 heat of the tropics proves no barrier to other northern species 

 which, from their superior swiftness of flight, require less specialized 

 conditions for their existence. 



Stercorarius antarcticus, 



■Lestris cutarractes, Quoj' and Gaimard, Voy. * Uranie,' p. 137, 

 Atlas, pi. 38 (1824) (Falkland Islands); Gould, B. of Aust. vii. pi. 

 21 (1848); Hutton, Ibis, 1872, p. 248 {Chatham Islands). 



Lestris antarcticus. Lesson, Traite d'Orn. p. 616 (1831); Scl. 

 and Salvin, P. Z. S. 1871, p. 579 (part). 



Megalestris antarctica, Gould, P. Z. S. 1859, p. 98. 



Lestris antarctica, Sclater, P. Z. S. 1860, p. 390 ; Abbott, Ibis, 

 1861, p. 165 (Falkland Islands). 



Lestris fuscus, Ellman, Zoologist, 1861, p. 7472. 



Bupha ff us antarcticus, Coues, Proc. Phil. Ac. 1863, p. 127; B. 

 N.W. Am. p. 604 (18/4). 



Lestris catarrhactes, Hutton, Ibis, 1867, p. 185. 



Stercorarius antarcticus (et madagascarensisi), Bp. Consp. Av. 

 ii. p. 207 (1857) ; Von Pelzeln, Novara-Reise, Vogel, p. 150 (1865) 

 {St. Paul's I.) ; Buller, B. New Zealand, p. 267 (1873). 



Stercorarius catarractes (6), Schlegel, Mus. P.-B. p. 47 (1865); 

 Layard, B. S. Africa, p. 366 (1867) ; Sharpe, Zool. 'Erebus and 

 Terror,' i. App. p. 32 (1875). 



Buphagus skua antarcticus, Coues, in Bull. U.S. N. M. no. 2 

 p. 9 (1875) (Kerguelen Island)*. 



Quite irrespective of the enormous gap which, so far as we know, 

 at present separates the geographical range of S. catarrhactes from 



* Since writing the present article I have read the very interesting ac- 

 count of the habits of this species as observed at Kerguelen's Island bv Dr. 

 Kidder, Naturalist to the American Expedition to observe the Transit of Venus. 

 It would appear that it avoids the water, and preys princiiDally upon other 

 birds; there are also other modifications of the usual habits of birds of this 

 genus, to which space will not allow me to allude. 



Proc. Zool. Soc— 1876. No. XXI. 21 



