52 



ARKIV FÖR ZOOLOGI. BAND 13. N:0 4. 



Thayer and Bångs described the Blue Tanager of the 

 Pearl Islands as a separate subspecies, T. c. dilucida. About 

 the characters of this insular form they state, that the bird is 

 similar to T. cana cana Sw., but larger, with a larger bill 

 [male: wing 92 (90—94); tail 65,1 (62—67,5); culmen 14,2 

 (13,8—15); female: wing 86,8 (85,5—88,5); tail 61,3 (60,5—62); 

 culmen 13,7 (13,2 — 14)]; brighter blue, less greenish, on mar- 

 gins of wing- and tailfeathers; lesser and middle wingcoverts 

 darker and brighter blue; rump and upper tailcoverts, usually, 

 decidedly bluer and less greenish. The quoted authors say 

 about the subspecies, that it is closely related to T. c. cana, 

 and that «some single individuals might pro ve troublesome, 

 but in series the differences stånd out fairly well». 



I have compared the present Pearl Islands specimens 

 with the following ones from the mainland of Central America 

 (coU. BovALLius): 1 c^, Panama, Pacora, March 3; 2 (^<^, 2 $$, 

 Nicaragua, San Juan del Norte (Greytown), March 30, October 

 27, November 3 and 8. 



As to the colour, I cannot separate the mainland and in- 

 sular birds. The brightest coloured specimen from Nicaragua 

 ((^, Nov. 3) is slightly bluer on wings and tail than the male 

 specimen from Saboga, and on back and upper tailcoverts 

 decidedly bluer than the latter. The Sabogan male has the 

 smaller wingcoverts more violet blue than the specimens from 

 Nicaragua, but in the male from the isthmus of Panama this 

 colour is still more pronounced and consequently it is not 

 peculiar to the island birds. The female from Saboga (that 

 from Trapiche is a young bird, useless for comparing) has wing, 

 tail and back tinged with green but not so strongly as the 

 present females from Nicaragua. 



As to the measurements the sj^ecimens from the Pearl 

 Islands are somewhat greater, as shown in the following table 

 of measurements. 



cT, Saboga I. {T. c. dilucida) . 

 cT, Panama (T. c. cana) 



(f, Nicaragua 7^' >' » 

 ef, Nicaragua ^"jio » » 

 9 , Saboga I. {T. c. dilucida) . 

 9 , Nicaragua ^/u {T. c. cana) 

 9 , Nicaragua ^^Ji » » 



