398 MR. H. SArNDERS ON THE GEOGRAPHICAL 



chain, for no similar gull occurs on Kerguelen or any of the in- 

 termediate islands, a closely allied, but perfectly separable spe- 

 cies, L. Jiartlauli, turns up at the Cape of Grood Hope. New 

 Zealand also produces another species, L. hulleri, Potts, belong- 

 ing to the same group, but varying rather more in its wing-pattern 

 from L. scopulinus than that species does from the other two. 

 L. lulleri seems to be rather a frequenter of inland waters, but 

 all the others are sea-g\xW^, and, as has been observed, they form 

 an isolated group. Bonaparte united them in the same subgenus 

 with L. gelastes of the northern hemisphere ; but the resemblance 

 between them seems to me to be extremely superficial. 



It is generally admitted that at one time Europe was united 

 to Northern Africa at the Straits of Gribraltar, and again at Cape 

 Bon in Sicily, the present Mediterranean sea being then divided 

 into two great lakes. These barriers have long been broken 

 down, yet there exists a gull which even now scarcely strays 

 beyond the ancient limits of one of these inland lakes. This spe- 

 cies is L. audouini, Payr., a long-winged bird similar to and nearly 

 as large as a Herring-gull, but with black legs and a cherry-red 

 bill crossed by a double transverse zone, its headquarters being in 

 the vicinity of Corsica and Sardinia, and its occurrence has never 

 been authenticated beyond Spain on the one hand, and Sicily on the 

 other. There are scarcely two other species which have so circum- 

 scribed an area, and in a sea-gvUl this isolation is very remarkable. 

 On the same waters, but with an extension of range as far as the 

 Black, Caspian, and E-ed seas, and thence to Scind, is found L. ge- 

 lastes, a slender gull, which, although devoid of a hood at all seasons, 

 has close affinities with those species which bear a coloured hood in 

 the breeding-season only, and which have next to be considered. 



The typical Hooded Gulls are, with one exception, small or 

 medium-sized birds ; and as regards number of species, the group 

 is better represented in the northern hemisphere than in the 

 southern. Indeed the whole of the south-eastern portion of the 

 globe can show but one solitary species, i. pliceocephalus, Sw., a 

 South -African form with a pale grey hood, closely allied to, and, 

 in fact, only just separable from, L. cirrJiocephalus, Vieill., which 

 inhabits the opposite coast of Brazil and the Eio de la Plata 

 States, and has also, strange to say, been twice obtained on the 

 Pacific near Lima. How it gets there is not known, the interval 

 being absolutely unbridged, but the fact is undoubted. The 

 African species is probably an offshoot of the American form,inas- 



