NO. 4 



AVIAN GENUS CLAMATOR — FRIEDMANN 



67 



in the more southern population of jacobinns {scrratus) we find a 

 markedly different egg type, but the difference here is just as great 

 between sections of this species as between it and levaillantii. There 

 can be no reasonable doubt as to the close relationship of the two 

 species. 



Inasmuch as it is thought that the southern serratus is nearer to 

 ancestral C. jacohinus than are the other races of the species, it would 

 follow that the evolutionary trends in plumage pattern involved a 



4 



Fig. 14. — Variation in pectoral markings. 

 Clamator levaillantii: 1, Darkest; 3, palest. 

 Clamator jacobinus: 2, Darkest; 4, palest. 



loss of the pectoral shaft stripes giving rise to C. j. pica and C. j. 

 jacobinus on the one hand, and a great intensification of the same 

 character giving rise to C levaillantii. From the sermtus-like pri- 

 mordial stock both developments arose and diverged. 



It may be remarked that it seems (to human eyes) that some 

 plumage characters of no great biological significance are tenaciously 

 retained during evolutionary changes while others of no more obvious 

 utility are altered. An example of the former is the white wing patch 

 found in both the pale and the melanistic morphs of both jacobinus 

 and levaillantii, although this may have a recognition and a releasing 

 function in both species. 



Clamator glandarius 



The one feature of greatest evolutionary significance, or, to put it 

 in a different way, the one phylogenetic clue of greatest interest in 

 the plumages of this, the climax species of the genus, is the fact that 



