( 190 ) 



Gbnus XEMA Leach. 



Xema, Leach in Jtnss's Voyage Baffin's Bay, App. II. p. LVU. tab. (1819). 

 Creagrus, Bonaparte in Naumannia, 1854, p. 213. 

 Chema, Eeichenow in Juurn.f. Orn. 1889, p. 188. 



In placing the large Galapagos gnll in the genus Xemn, we are following the 

 Catdlofiue of Birds (Vol. XXY.), not being at present in a jiosition to discuss the 

 genera of the Laridae, but it is with some relnctance that we unite Xema and 

 Crenffriis into one genus. The ditterences between the two forms, on the other 

 hand, are not so important as Ridgwa.y makes thom out to be. The beak is more 

 curved in Creagrus, somewhat higher near the base, and the tarsus is of the same 

 length as the middle claw, while in Xema saljinei the tarsus is much longer than 

 the foot. This latter character is the only one that might be considered to be of 

 generic importance, but if this principle is adopted, then several more divisions will 

 have to be accepted than Mr. Saunders admitted in the Catalogue of Birds, 

 Vol. XXV. (cf. p. 1(51, where the following genera are adopted: Xema,Rliodostetliia, 

 Larus, Gubianns, Leucopha^eus, Pagophila^ and Rissa). 



1. Xema furcata (Xeboux). 



.l/V);/e//f a (lueuc fourchue , Neboux in 7?er. Zou]. 1840, p. 290. 

 Lnriix fiircalun, I.e. ; Vny. Vtims, Atlas PI. X. (1846). 

 Creagrus fureuiiis!, Salvin in Trans. Zntil. Soc. IX. p. 5015. 

 Xema fiircaliim, Saunders in Proc. Znol. Soc. 1882, p. 523. pi. ;>4. 

 Xema fiircain, Saunders, Cat. B. Bril. ^fus. XXV. p. 165. 

 Creagnin furraliif!, Ridgway in Proc U.S. Xat. JAj/.s. XIX. p. fi.SS. 



This beautiful gull is evidently very common at the Galapagos Islands, where 

 it may be seen near most of the islands, from Culpepper to Hood, but it finds 

 suitable nesting-j)laces on a few of the islands only. It is also known to occur nff 

 the coast of Peru and at Malpelo Island, but the original locality " Monterey, 

 California," cannot be accepted, as Monsieur Neboux, who brought the specimen 

 home, came from the Galapagos Archipelago ! Ridgway and Saunders gave the 

 most accurate and most detailed descriptions of this gull. 



Numbers were found breeding in July on Wenman and ('idi)e])per, in October ou 

 Tower, and in December on Hood Island. The number of eggs was only one in every 

 case. The nest consisted of pebbles, or peltbles and pieces of bones, placed among 

 the rocks on the cliffs, but some were also found without any indication of a nest 

 (in the bare ground among the rocks. The eggs resemble tiiose of other gulls, and 

 vary in the same way. They are more or less regularly ovate (Ridgw. pi. XVI. 

 fig. 1). Most specimens are very light greenish or bluish white with large and bold 

 spots and patches of a very dark brown, and with underlying greyish-manve spots. 

 The spots are either spread all over the egg, or accumulated near the thick end, 

 and sometimes form a loose ring near the thick end. Hair-like lines are not often 

 seen. Some of the eggs are of a light reddish or brownish tieshy ground-colour, 

 but all are light sea-green if held against the light. They measure (54 by 47-5, 

 0(5 by 4(j-5, (5(5 by 40, 04 by 40, 00 by 44-.5 mm., and so on. 



Genus STERNA L. 



."ilenia, Linnaeus, Si/Kt. Xai. I. p. 137 (1758). 

 Cosmopolitan. 



