The Zoologist— October, 1870. 2333 



The specimen above described, collected at San Diego, California, 

 by Dr. J. G. Cooper, is a little larger than the type, as will be seen by 

 comparing the measurements with those in the accompanying foot-note. 

 It is also described as representing the perfect plumage, — the type being 

 imperfect in this respect. The upper parts are of a unifoi'm very dark 

 cinereous, witl)out a shade of brown ; the latter hue only occurring in 

 specimens with worn and faded plumage. In the original description, 

 here appended, the indications of the size of relative lengths of the 

 tarsus and middle toe are made without reference to the claw ; which 

 fact explains an apparent discrepancy between the present description 

 and the original one. The tarsus is exactly as long as the middle toe 

 without its claw. 



This is a very strongly marked species. The most striking 

 diagnostic feature is the pure white of the under surface of the wings. 

 In the uniformity of the cinereous colour of the upper parts it is also 

 unique. Nearly the same length of tarsus is found in B. brachypterus, 

 Brandt, and Craveri, Salvadori ; the tarsus is much shorter than the 

 middle toe in Wrangeli, Brandt, marmoratus, Gm., " Kittlitzii," 

 Brandt, and " breviroslris," Vigors. 



This species is certainly not the Uria brevirostris, Vigors, from San 

 Bias. This is described as having " alae supra et infra, tectricesque 

 inferiores fuscse, * * tarsi j," which settles all questions on this 

 score. It has the same dimensions, and the same relative length of 

 tarsus and toes as Craveri, Salvadori, also from the coast of Lower 

 California ; but the latter appears to be a different species, as will be 

 discussed further on. It seems nearest to brachypterus, from 

 Unalaschka; in fact there is nothing in Brandt's brief diagnosis 

 preventing the reference of the present species to brachypterus, 

 except the expression " tarsi digito medio longiores." But in view of 

 this discrepancy, and of the widely separated localities whence the 

 two species are described, it would be unsafe to take their identity for 

 granted. It is much the best course to retain the present species as 

 it stands, under the name hopoleucus, which has the merit of being 

 positively identified, as is not the case as yet with brachypterus. 



Several excellent examples of this species from various points along 

 the coast of California are in the collections of the Smithsonian 

 Institution and Philadelphia Academy. They present no individual 



tarsus '85, middle toe [with claw] TOO. This specimen is consideral)]y weaihei- 

 beaten, and the old feathers of the^ upper parts are much worn, and bleached at the 

 edges. The new ones are, however, as described." 



SECOND SERIES — VOL, V. 8 D 



