THE BIRDS OF CLIPPERTON AND COCOS ISLANDS 507 



but only a few were seen elsewhere on the atoll. About the rookery they 

 were exceedingly noisy. All seemed to utter the same sounds, but so 

 great and continuous was the general din that individual voices could 

 hardly be distinguished. The sounds, however, differed from those of 

 Anous, mentioned below, in being much less distinctly composed of a 

 series of notes. They were more continuous, yet had a fairly evident 

 separation into three similar syllables. When driven from their eggs the 

 birds flew up in great numbers utteringthe same notes loudly and harshly. 

 The eggs are laid singly on the bare rock. In color they are creamy 

 whitish, marked with dark brown blotches and specks of varying in- 

 tensity. Sometimes spots of all sizes are evenly distributed over the 

 entire egg, in other cases the larger blotches are accumulated in a circle 

 about its larger end. Some have no large blotches, the markings con- 

 sisting entirely of small dark spots, or occasionally with very pale, 

 almost obsolete blotches. One egg appears very different from the 

 rest, being thickly covered uniformly with large elongate daubs of 

 reddish-brown, all placed obliquely in the sair^^ direction. Size, 

 46 X 33 to 54 X 38 mm. 



ANOUS STOLIDUS RIDGWAYI Anthony. 



Anous stolidus rousseaui Ridgway, Proc. U. S. Nat. Mus., xix, p. 645, 



1896 (Cocos Island). 

 Anous stolidus ridgiuayi Anthony, Auk, xv, p. 36, Jan., 1898 (Cocos and 



Socorro Islands). 



Range. — Eastern Pacific, north of the Galapagos : known from the 

 Rivillagigido Islands, Clipperton Island, Cocos Island and the coast 

 of Mexico. Boundary between this form and A. stolidus rousseaui 

 (Hartlaub) not known. 



Adult Fe7nale. — Cat. No. 5218, StanfordUniversity Museum, from 

 Cocos Island, July i , 1899. Top of head pearl gray, almost white ante- 

 riorlv, entirely white along a narrow line from bill to eye, bordering the 

 lores. Back of head becoming gradually darker, merging into the brown 

 of the mantle. Back, scapulars, upper tail coverts, wing coverts and 

 tertiaries pure dark sooty-brown. Alula darker dusky-brown. Pri- 

 maries and secondaries still darker blackish-brown, slightly paler on the 

 inner webs. Rectrices same color as the wing feathers. Under wing 

 coverts dark grayish-brown. Rest of under parts uniform in color 

 with the back. Throat with a very dark plumbeous tinge, giving it 

 a blackish tone in some lights. Lores and line from lores above the 

 eyes black. A white spot in the supraocular part of this line above 

 the posterior part of the eye. Sides of head dark plumbeous. Lower 

 eyelid edged with white. Bill black. Feet dark brown. 



