CALIFORNIA WATER BIRDS. 361 



recently irom the shell, each of the specimens I obtained 

 was brooding upon an egg. But one of the eggs was 

 sufficiently fresh to be easily blown. Judging from the 

 specimens examined, they are of greater size than those 

 of the Ashy Petrel. As is likewise the case in this latter 

 species, the markings are not always present on the larger 

 end, the egg sometimes being immaculate white. Two 

 of the birds dissected were males, showing that the du- 

 ties of incubation are shared by both sexes. 



The Petrel with a ' white rump ' seen by Dr. Cooper 

 near San Nicholas Island in July, 1863, and recorded in 

 the first series of the 'Proceedings' (vol. iv, p. n) as 

 perhaps being Oceanites oceanicus may have belonged to 

 the present species. 



Oceanodroma homochroa. Ashy Petrel. — i\lthough 

 these Petrels were breeding abundantly in all parts of the 

 island, every portion of it might have been passed over in 

 daylight without a single individual being discovered, for 

 apparently only brooding birds occurred, concealed in 

 loose piles of stone, in stone walls, and under drift-wood. 

 After nightfall the Petrels became active. They were 

 especially conspicuous during the early morning hours of 

 the 14th when the Auklets held their concert. As I stood 

 in the dooryard of a keeper's house, every few moments 

 one or more would pass silently by, disappearing in the 

 darkness. Their flight recalled that of a Goatsucker. 



The strong musky odor of the Petrels renders their 

 discovery in the rock piles easy. It is only necessary to 

 insert the nose into likely crevices to find them. With 

 little practice one may become very expert in this kind of 

 hunting, readily determining whether it is an Auklet or a 

 Petrel that has its residence in any particular cranny. 

 Sometimes the Petrels are within reach, but usually the 

 rocks have to be removed to get at them. When uncov- 



Paoc. Cal. Acad. Sci., 2d Ser., Vol. VI. ( 26 ) August 29, 1896. 



