210 CALIFORNIA ACADEMY OF SCIENCES. 



well represented among mammals the white face mark- 

 ings and ringed tail of the raccoon (Procyon lotor) being 

 an admirable example, but instances are not lacking 

 among birds. Here, however, it is more difficult to 

 distinguish them from other forms of recognition marks, 

 but future study with this end in view will undoubtedly 

 disclose many examples. In the corner of my sleep- 

 ing room, just opposite the foot of the bed, stands a 

 mounted western great horned owl (Bubo virginianus 

 subarcticus). On awakening one morning before dawn 

 a white spot caught my eye which at first I was unable 

 to account for. It soon occurred to me that it was the 

 white throat patch of the owl, and such it proved to be, 

 standing out with wonderful clearness as relieved by 

 the dark plumage surrounding it. It is easy to see how 

 valuable this mark would be to a family of owls in the 

 prosecution of their domestic duties. The white throat 

 patch of the night-hawks (Chordeiles) would be similarly 

 useful. The conspicuous white markings on the eye- 

 brows, chin and chest of the burrowing owl (Speotyto 

 cunicularia hypogcea) is an admirable instance of a 

 socialistic mark which is useful in the darkness of the 

 burrow. Many of the white markings about the heads of 

 woodpeckers doubtless serve the same purpose, and also 

 the white throat of the belted kingfisher (Ceryle alcyon) 

 and the white breasts of the white-breasted swallow 

 ( Tacky cinetabicolor) and the violet green swallow (T. thal- 

 lassina). In these instances the white color is of that 

 peculiar purity that would be especially conspicuous in 

 the darkness of a burrow. The white feathers of downy 

 young birds are doubtless of no utilitarian significance 

 so far as their origin is concerned, but would neverthe- 

 less serve to mark the position of the bird in the nest 

 if in a dark burrow or hole. 



