Chapman — Variation in Ostinops Decumanus. 



31 



Conclusions. 



First. — Practically all male, and most female specimens of Ostinops 

 decumanus from south of the Amazon exhibit a varying number of feathers 

 which in whole or part are yellow, yellowish and rarely white. The pres- 

 ence of these feathers produces a pied appearance which in an individual 

 specimen would be considered abnormal, but which in the present in- 

 stance seems to be of racial significance. 



Second. — This pied character is practically absent north of the Amazon. 



Third. — Ostinops decumanus reaches its maximum size in northern 

 South America from northeastern Venezuela to Colombia; its minimum 

 size at the southern limit of its range. Specimens from the northern 

 limit of the bird's range are intermediate in size but nearer those from 

 Colombia. 



Fourth. — Males are more variable in size, both individually and geo- 

 graphically, than females. 



Fifth. — The wings and tail in adult males vary markedly both in size 

 and shape from those of less mature birds, the difference being in part 

 due to age, in part to sexual causes. 



Sixth. — The species may be further divided into geographic forms based 

 upon degrees of difference in general coloration, but the material at hand 

 does not warrant definite expression of opinion in this connection. 



Measurements of Adult Males. 



Locality. 



Chiriqui, Pan. ... (5) 



Colombia (5) 



Paria Pen., Ven. .(3) 



Tobago (1) 



British Guiana. . . (1) 

 Dutch Guiana.. . . (1) 

 Marajo, Brazil. . .(1) 

 Santarem, Brazil. (1) 

 Solimoes, Brazil. .(1) 

 Napo, Ecuador.... (1) 



Bolivia (9) 



Chapada, Brazil.. (7) 



Wing. 



218-231; av. 



228-249; av. 



231-241; av. 



201 



201 



233 



218 



224 



228 



247 



222-245; av. 



205-239; av. 



229 

 237 

 234 



230 

 220 



Tail. 



184-200; av. 192 



188-210; av. 195 



195-198; av. 196 



186 



177 



183 



167 



173 



182 



212 



156-193; av. 180 



165-181; av. 173 



Cultnen. 



60-64; av. 62.2 

 63-66; av. 64 J 

 70.5-71 ;av. 71.0 



65 



61.5 



64 



60 



58 



58 



65 

 56.5-62; av. 59.4 

 54-59.5; av. 56.1 



