NATURAL SCIENCES OF PHILADELPHIA. 311 



Does the female of this specie3 have a browo head ? I am inclined to the 

 contrary opinion. If Audubon's assertion to the fact of having seen Gulls 

 with brown heads be true, they were probably of a different species. 



[All the preceding species of Chrokocephalus acquire during the breeding 

 season, a beautiful delicate rosy blush on the white of the under parts.] 



0. Very small; bill exceedingly slender and compressed; tarsus shorter 



than the middle toe and claw. 



12 Cfiroicocephalus minutus Bruch ex Gmel. 



Larus, minutus, Gmel. 1788. Hydrocohvus minutus, Kaup, 1829. Xemaminu- 



tum, Bp. 1838. Gavia minuta, Macgill. 1842. Chrokocephalus minutus, 



Bruch, 1855. Larus melanotis, Lesson, fide Bruch. 



Sp. Char. Smallest of the genus. Length 11-50. Bill above -90, along gape 



1-40; tarsus, -90, middle toe and claw 1-10. Under surface of wings deep blackish 



slate. 



Habitat. Europe. ? Northern North America (accidental.) 

 Professor Baird thinks that there is no good reason to consider this bird an 

 inhabitant of or even a visitor to North America. It has been included in our 

 fauna on the strength of a statement of Sabine, who saw a small Gull, with 

 black head and bill, greatly resembling the Larus minutus. This, however, was 

 before Larus Bonapartei {Chrokocephalus Philadelphia) was described and made 

 known by Richardson in the F. B. A., and a poorly preserved or immature speci- 

 men might easily be referred to Larus minutus by one ignorant of the existence 

 of two species. 



Genus VI. Rhodostethia Macgill. 



Rossia, Bp. 1838; (nee Owen.) 



Rhodostethia, Macgill. 1842 ; (t. Larus roseus Macgill.) 



23. Rhodostethia rosea Bp. ex Macgill. 



Larus roseus, Macgill. 1824; descriptio nulla. A 'hodostethia rosea, Bp. Ros- 

 sia rosea, Bp. 1831. LarusRossii, Richardson, 1825 ; descriptio hujus avis 

 prima. Rhodostethia Rossii, Macgill. 1824. 



Sp. Char. " Scapulars, inter-scapulars, and both surfaces of the wings clear 

 pearl gray ; outer web of the first quill blackish brown to its tip, which is gray : 

 tips of the scapular and lesser quills whitish. Some small feathers near the eye. 

 and a collar round the middle of the neck, pitch-black. Rest of plumage white, 

 the neck above and whole under plumage deeply tinged with peach blossom red 

 in recent specimens. Bill black, its rictus and the edges of the eyelids reddish 

 orange. Legs and feet vermillion red ; nails blackish. Length 14 inches, wing 

 10*5, tail 5-5. Bill above, -75, along gape 1.25, tarsus 1. 1-12." (Richardson). 



Habitat. Arctic Regions. 



We have never had the pleasure of examining a specimen of this exquisite Gull, 

 and are therefore obliged to copy the description from Richardson. This au- 

 thor admits that the bird was named Larus roseus the year before he called it 

 L. Rossii; but claims precedence for his name, on the ground that his was the 

 first published description. 



Genus VII. Xema Leach. 



Xema, Leach, 1818 ; (fide Gen. Rep. t. Larus Sabini, J. Sab.) 

 Gavia Macgill. 1842. p. 



24. Xema Sabini Leach ex Sab. 



Larus Sabini, J. Sab. 1818. Xema Sabini, Leach, 1825. Gavia Sabini, Mac- 

 gill. 1842. 



Sp. Char. Adult, breeding plumage. Bill black to the angle, abruptly bright 

 chrome from angle to tip. Mouth bright orange; eyelids orange ; legs and feet 

 black. Hood uniform clear deep slate, bounded interiorly by a band, narrowest 



1862.] 



