Todd-Carriker : Birds of Santa Marta Region, Colombia. 461 



Sixteen specimens : Fundacion, Tucurinca, Mamatoco, La Tigrera, 

 Trojas de Cataca, and Don Diego. 



The six forms of Dacnis cayana listed by Mr. Hellmayr (together 

 with D. c. Paraguay cnsis — not seen by the writer) fall naturally into 

 two groups, characterized by a difference in color. The first group, 

 composed of cayana, glaucogularis, and callaina, are decidedly more 

 greenish (nearest beryl green) in general coloration, so far as the 

 males are concerned, while in the second group, comprising ultrama- 

 riua, napcca, and cocrcbicolor, the color varies from light cerulean blue 

 to phenyl blue. Of these ultramarina is the most variable, but is 

 nevertheless easily referable to this group. Females differ in a cor- 

 responding manner, those of the first group having the pileum and 

 sides of the head much duller, paler, and more greenish blue than 

 those of the second group. It is fair to presume that these two groups 

 represent two specific types; at least, this would seem to be a more 

 logical arrangement than to consider such dissimilar forms as cayana 

 and cocrcbicolor to be conspecific. The only objection to such a 

 course arises from the circumstance that the range of the first group 

 would thus be rendered discontinuous, since callaina, from Chiriqui 

 and southwestern Costa Rica, is isolated from its nearest allies by the 

 interposition of a form belonging to the other group. Such a dis- 

 tribution need not militate against the proposition here advanced, how- 

 ever, in view of other similar cases which have long been rec- 

 ognized, as for instance that of Thamnophilus doliatus and T. radiatus, 

 which has certain points in common with the present case. 



Dacnis cocrcbicolor napaca, as the present bird must be called if the 

 above considerations are granted, is clearly an intermediate form be- 

 tween D. c. ultramarina of Panama, eastern Costa Rica, etc., and D. 

 c. cocrcbicolor of the Bogota region of Colombia, as already indicated 

 by Mr. Hellmayr, examples from western Colombia being intergrades 

 between cocrcbicolor and napcca. Indeed, considerable variation in the 

 shade of blue is shown by the present series, although none compare 

 favorably with cocrcbicolor. Two females from Don Diego, on the 

 north coast, differ from all the other birds of that sex from various 

 localities in the Magdalena basin in having the pileum paler, more 

 greenish blue — a fact which may or may not be significant. 



This species is mainly a bird of the Lower Tropical Zone, ranging 

 over the whole of the lowland belt from Fundacion to Dibulla, as well 



