310 CALIFORNIA ACADEMY OF SCIENCES. 



some with and some without eggs, deserted, probably, on 

 account of long continued wet weather. The location of 

 the nest, however, plays an all-important part in the success 

 or failure of the first builders. A few birds began the con- 

 struction of their nests in December, and one had her work 

 nearly completed on the 25th of December, 1885. Four 

 fresh eggs were found in it on January 17th. The breeding 

 season, strictly speaking, extends from the middle of Jan- 

 uary through the month of March. 



Nests were found in cavities of immense boulders, under 

 rocks, in fallen and decayed trunks of cypress trees, the 

 latter location being apparently a favorite one. But wher- 

 ever the nests were located the passages leading to them 

 were, with one or two exceptions, paved with flat pebbles 

 ranging in size from a Lima bean to a half dollar. Fully a 

 quart of these pebbles were removed from the entrance to 

 a nest built in a boulder at a height of four feet, where, at 

 some previous time, other birds had evidently built and 

 accumulated their share of the pavement. As a rule scarcely 

 an ordinary handful of stones are used. The nest is built 

 in close conformity to the size and shape of the cavity 

 which it occupies, being usually circular and varying from 

 a shallow bed of fine dry grasses to a nest of the same ma- 

 terial measuring 150 mm. in diameter and 60 mm. high. 

 The egg receptacle is from 55 mm. to 70 mm. in diameter, 

 and not more than 30 mm. in depth. A lining of goat 

 hair when obtainable is invariably used. I followed one 

 bird fully an hundred yards from the spot where she had 

 collected some goat hair before the nest was reached. 



The eggs are usually four, though sometimes five in 

 number, and resemble both in color and shape those of 

 the common rock-wren {S. ohsoletus). 



Set No. 781 (author's oological collection) measures: 

 17 X 14; 17 X 14.5: 18 x 14.5; 18.5 x 14.5 mm. 



Set No. 782 (author's oological collection) offers the fol- 



