364 



SNODGRASS AND HELLER 



the order of derivation has been the other way, /. ^., that the Abing- 

 don form has been derived from the Tow^er race, for the latter is in- 

 termediate between it and the Chatham species. Hence, if the Ab- 

 ingdon form were named according to its zoological relationship it 

 would be called '-'■Nesojnim.us bauri -personatus " ; but, since the Abing- 

 don race was described first, the names, according to the present canons 

 of nomenclature, must stand as given above. 



Color of upper parts still darker than in the Tower race, the black- 

 ish color of the head pervading also on the back, the whole dor- 

 sum being very dark and the lighter margins of the feathers inconspic- 

 uous. The nuchal collar is well marked only on the sides of the 

 neck ; across the nape it is almost obsolete. The sides of the breast 

 are strongly shaded with buff as in the Tower form. A faint trace of 

 a dark maxillary stripe is present in several specimens. 



MEASUREMENTS OF ADULT SPECIMENS OF NeSOmimUS 



personatus personatus. 



The color of the back of the Abingdon specimens does not directly 

 grade into that of the Tower specimens, but it does do so through 

 those from Bindloe. The latter, however, lack all traces of the maxil- 

 lary stripe. The bills of the Tower specimens average slightly 

 larger than those from Abingdon, while the latter have bills a little 

 larger than those of the Bindloe specimens. The bills of the Bindloe 

 and Tower specimens intergrade in length only through the Abingdon 

 specimens. Since these different sets of characters do not grade in 

 the same direction, it is perhaps most probable that the Abingdon 

 and the Bindloe races have been derived separately from the Tower 

 form, yet they all intergrade in such a manner that we cannot name 

 them as distinct species, although both the Abingdon and the Bindloe 

 forms have characters that do not directly grade into those of the 



