366 



SNODGRASS AND HELLER 



This form is scarcely distinguishable in color from N. fersonatus 

 bauri of Tower. The specimens average slightly darker in color of 

 the back than do the Tower specimens and the maxillary stripe is 

 somewhat more strongly developed. The bill, however, is consider- 

 ably shorter, averaging in our Culpepper specimens, 26 and in the 

 Tower specimens 27.5 millimeters in length. The measurements, 

 however, in the two cases overlap, so that we can separate the Cul- 

 pepper form only subspecifically from the Tower race. 



Rothschild and Hartert make the Culpepper form a variety of N. 

 melanotis. It differs, however, specifically from true varieties of N. 

 melanotis in the blackish color of the back and the presence of the 

 dark maxillary stripes. 



The collection contains three adult males and two adult females 

 taken on Culpepper in December. 



MEASUREMENTS OF ADULT SPECIMENS OF NesomimUS 



personatus hulli. 



From the preceding descriptions it will be seen that the mocking- 

 birds inhabiting the most northern islands of the archipelago, with the 

 exception of Wenman, viz. Tower, Culpepper, Abingdon and Bindloe, 

 are interrelated to one another in such a manner that they form four 

 varieties of one species. They are all characterized by a melanistic 

 tone to the feathers of the head and generally of the back, being thus 

 distinguishable from those forms inhabiting the central and southern 

 islands of the archipelago, which have a brownish tone pervading the 

 upper parts. These northern forms must be named as varieties of the 

 Abingdon race N. personatus, because this was the first one described ; 

 but their relationship is probably severally with the Tower race, N. 

 personatus hulli, since this one most resembles the Chatham race to 

 which the melanistic forms are probably related on account of the 

 retention by most of them of the dark maxillary stripes, but from 



