BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 133 



board from ships at anchor in the harbor. The species was re- 

 corded near Montevideo and Carrasco, Uruguay, on January 9 and 

 16, 1921. At nightfall I observed them passing along the coast 

 to some resting place to the eastward. A few were observed at La 

 Paloma, Rocha, on January 23. Near Guamini, Buenos Aires, on 

 March 5 I was rather surprised to observe three in company with 

 flocks of Larus maculipennis about the large lake near town. Larus 

 doviinicamis was more usual in occurrence near the coast, j^t came 

 here about 120 miles inland. 



The species is similar in habits and notes to large gulls of the 

 North' rn Hemisphere. 



LARUS MACULIPENNIS Lichtenstein 



Larus maculipennis Lichtenstein, Verz. Doubl. Zool. Mus. Berlin, 1823, 

 p. 83. (Montevideo.) 



The brown-hooded gull is the most common of the lariform birds 

 found on the open pampas. An adult male taken at Lavalle, Bue- 

 nos Aires, on October 29, 1920, was in full plumage and about to 

 breed. In this bird when freshly killed the bill was Vandyke red; 

 margin of eye-lids dull Brazil red; iris Vandyke brown; tarsus 

 and toes Vandyke red; and nails dull black. The colors of bill and 

 legs have become somewhat duller in the dried skin. One of two 

 females secured on the coast 15 miles below Cape San Antonio 

 on November 3 is in winter plumage with brown feathers of the 

 Juvenal plumage present on the lesser wing-coverts. In the other 

 the dark hood is indistinctly outlined on the crown and sides of the 

 head, with scattering dark feathers on the throat. In both speci- 

 mens the ends of the inner secondaries are grayish brown and the 

 tail is tipped with dull black. Both have the feathers of wings 

 and tail considerably worn. An adult female secured at the Laguna 

 Castillos, near San Vicente, Department of Rocha, Uruguay, on 

 January 31, 1921, is in full winter plumage except that the outer 

 primaries are being renewed. The plumage of the breast has a faint 

 rosy tint. Two adult males in full winter plumage (one prepared 

 as a skeleton) were secured at Guamini, Buenos Aires, on March 5, 

 and a skull was taken from a dead individual on the same date. 

 The skin preserved shows a few pin feathers on the ventral surface. 

 From other specimens at hand it appears that the post-breeding 

 molt is completed about the end of March. 



The genus C hroicocephalus that has been used for the hooded 

 gulls (including L. cirrocephalus and L. maculi'pennis) is seemingly 

 based entirely on differences in color and color pattern. Several 

 years ago I examined the skeleton of Larus franklini, 'Philadelphia, 

 and atricilla, and several species considered to represent typical 

 Larus, but after careful study was unable to make out structural 

 54207—26 10 



