ORNITHOLOGY OF GUADALUPE ISLAND. 311 



lowing measurements in millimeters: 19 x 14; 19 x 14; 

 19.5 x!4.5; 19.5 x 14.5; 19.5 x 15. 



The average size ascertained from a series of fifty-five 

 eggs, is 19 x 14 mm. 



The two largest eggs measured 21 x 15 mm. and 20 x 16 

 mm. respectively; the two smallest, 17 x 14 mm. 



Two different stages of the young plumage were taken, 

 descriptions of which are here given : 



Ch. Young. Above similar to adult but much darker, 

 especially the head and neck, which lack the speckled mark- 

 ings. Wings and tail as in adult but darker, the bars 

 across middle tail-feathers dull black. The outer half of the 

 pale cinnamon on end of tail-feather finely mottled with 

 dusky. Under parts pale pinkish cinnamon; the entire 

 throat obscured with a faint dusky suffusion. Crissum 

 darker than abdomen and unmarked. 



Wing, 67 mm. ; tail feathers, 53 mm. ; bill from nostril, 12 

 mm.; tarsus, 19 mm.; middle toe, 13 mm. 



(No. 2530 Immature, author's collection. Guadalupe 

 Island, February 19, 1886.) 



First Plumage. Above lighter than the immature speci- 

 men and grayer than the adult plumage. Below, including 

 throat, pale sulphurous white, becoming pinkish on sides, 

 and crissum, which is unmarked. 



Wing, 57 mm.; tail feather, 34 mm.; bill from nostril, 8.5 

 mm.; tarsus, 20.5 mm.; middle toe, 14 mm. 



(No. 2425 Nestling, author's collection. Guadalupe 

 Island, January 23, 1886.) 



By the table of measurements it will be seen that the bills 

 of specimens (collected eleven years after the species was 

 discovered) average about 15.5 mm.; while those taken in 

 1875 I find to averago fully a millimeter less. A decade 

 hence it will be interesting to know whether this increasing 

 development has still continued. 



