1905.] NATURAL SCIENCES OF PHILADELPHIA. 687 



Polioptila oaerulea obscura Ridgw. Western Gnatcatcher. 



One from the Mexican boundary and one from Bruce's ranch. 

 "Abundant and always making a fuss out of proportion to its size." 



Polioptila plumbea Baird. Plumbeous Gnatcatcher. 



Specimens from Bruce's ranch, Pescadoro Slough and the Cocopah 

 Mountains. 



Mimus polyglottos leuoopterus (Vigors). Western Mockingbird. 



Three examples from the Cocopahs. 



" I do not remember seeing any other specimens than those noted at 

 our Mount ]\Iajor camp. They were beginning to sing." 



Additional Species Observed by Mr. Rhoads. 



Larus occidentalis Aud. Western Gull. 



Very abundant on the Colorado and its tributaries. 

 Larus argentatus Linn. Herring Gull. 



A few seen on both the Colorado and the Hardy. 



Larus californious Lawr. California Gull. 



A few seen. 



Larus heermanni Cass. Heermann's Gull. 



A few seen as far up as Yuma, Arizona, 



Sterna elegans GambelT 



A few terns were seen in pairs on all the waters visited, either S. 

 elegans or S. dougalli or both. 



Sterna antillarum (Less.)? Least Tern. 



Three or four very small terns were probably this speqies. 



Phalaorocorax mexicanus (Brandt). Mexican Cormorant. 



Exceedingly abundant, fishing in great shoals with the pelicans. 



Peleoanus erythrorhynchos Gmel. American White Pelican. 



"Increasingly abundant as Yuma disappeared in om" wake, these 

 splendid lordly birds were an ever-present source of delight and admi- 

 ration during the remainder of our journey. At our camp on the upper 

 Hardy at Mount Major, they came regularly every morning to fish in a 

 lagoon formed by the recent floods directly in front of the cami^. 

 Sometimes there would be half a thousand of them, with hundreds of 

 Cormorants plunging about at once. On the outskirts of the fray Great 

 White Egrets gathered the fragments of this royal feast. 



Merganser americanus (Cass.). American Merganser. 



A few. 



