526 MK. H. SAUNDERS ON LARID^K [June 6, 



under the name of L. cirrhoeephalus, has induded two other and 

 perfectly distinct species. His no. 87 is really L. glaucodes, 

 Meyen (as is also his no. 51, which is rightly named), a species 

 with a black or dark brown hood (similar in that respect to our 

 L. ridibundus), which ranges from the Falklands to the coast of 

 Chili. On the other hand his nos. 68 and 69 are respectively young 

 and adult of i. maculipennis, Licht., another rfarA-hooded Gull, very 

 close to L. glaucodes, but from which it is distinguishable by the 

 wing-pattern. Hitherto L. maculipennis, which is the common 

 Argentine species, has not been known to occur beyond the Chuput 

 valley. Eastern Patagonia, 43° S. ; and this is the first time it has been 

 obtained on the Pacific coast. It was already sufficiently remarkable 

 that two such very closely allied and yet perfectly distinguishable 

 species of Gull as L. maculipennis and L. glaucodes should be coex- 

 istent within so limited an area ; but now that their range is shown 

 to intersect, it is stranger than ever. Reverting to L. cirrhoeepha- 

 lus, which has been so repeatedly confused with totally distinct 

 species, it may be excusable to repeat that it has a pale grey or 

 lavender hood, slightly darker on the neck, and that the only species 

 with which it can be confounded is its South- African representative 

 L. phceocephalus, Sw. 



Lartjs belcheri. Vigors. 



Larus belcheri, Vigors, Zool. Journ. iv. p. 358 ; Scl. & Salv. 

 P. Z. S. 1871, p. 575 ; Saund. op. cit. 1878, p. 182. 



[No. 4, San Lorenzo Island, Callao Bay, August 1881. Eyes 

 brown, legs yellow. 



No. 7, Callao Bay, August 1881. 



No. 8, Coquimbo Bay, November 1881.] 



The first is an adult with pure white head and underparts ; the 

 second is in the brown plumage of the first year ; the third is a bird 

 of the second year which has already assumed the dark mantle of 

 the adult, but still retains the brown hood and slightly mottled 

 underparts indicative of immaturity. 



This stoutly built species is a very remarkable Pacific form, uniting, 

 as it does, all the main features in which the Gulls of the Pacific 

 differ from those of the Atlantic. In the immature stage it has an . 

 exceedingly well-marked hood, which it afterwards loses ; in the 

 adult stage it still retains a very defined black bar on the rectrices. 

 Altogether it resembles L. crassirostris of Japan far more closely 

 than any other ; but it is a coarser species, and has a more defined 

 hood in the immature plumage than the Japanese bird. 



Larus modestus, a more slender but very characteristic species 

 frequenting the coasts of Peru and Chili, but of the breeding-place 

 of which no authentic accounts have yet appeared, is not represented 

 in this collection. Another and very rare Gull, hardlv a dozen 

 examples of which are known to exist, is Larus fuliginosus, a dark 

 sooty bird with a hood at all seasons, restricted to the Galapagos 

 group. 



