436 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



abdomen and under tail coverts lined, barred and spotted with sooty 

 gray. 



Measurements (from Ridgway, I.e., p. 682). — Males, wing 349- 

 374 (361.9), tail 172-243 (207.9), culmen 38-43.5 (40.4), tarsus 

 48-54 (52) mm. 



Females, wing 351-370 (359.7), tail 128-205.5 (182.2), culmen 

 38-44 (40.2), tarsus 50-55 (52.1) mm. 



Tarsus pale bluish gray on upper part in life ; lower part and feet 

 blackish brown. 



Migrant from the north. Known from sight records in Colon 

 harbor, and in the Gulf of Panama. 



Griscom (Amer. Mus. Nov. no. 282, 1927, p. 3) on March 13, 

 1927, in company with Maunsell Crosby, recorded several at Colon. 

 In later comment (Bull. Mus. Comp. Zool, vol. 78, 1935, p. 308) 

 he wrote that these jaegers sometimes enter Colon harbor where they 

 live on garbage and rob the many laughing gulls. Eisenmann has given 

 me a record of several seen at Coco Solo on April 28, 1961. Murphy 

 has seen them in late November (1956) parasitizing the laughing 

 gulls in the Gulf of Panama. On February 8, 1963, I saw one with 

 fully developed tail from the MV Pelican when off Isla Iguana. Cer- 

 tain other reports appear uncertain. 



No specimens have been collected. 



This species is of heavier form than the others of the genus, and 

 in the adult is distinguished by the form of the elongated central 

 rectrices which are broad at the tip, in addition to having the plane of 

 the web rotated or twisted toward the free end. 



STERCORARIUS PARASITICUS (Linnaeus) : Parasitic Jaeger; 

 Salteador Parasite 



Larus parasiticus Linnaeus, Syst. Nat., ed. 10, vol. 1, 1758, p. 136. (Coast of 

 Sweden.) 



Adult with slender, pointed central tail feathers projecting from 

 12 to 100 mm. 



Description. — Bill heavier ; length of horny cere (supranasal 

 saddle) from base decidedly more than the length of the distal, 

 hooked section (dertrum). Length, adult 450 to 470 mm.; immature 

 420 to 440 mm. Adult, light phase, upper surface and under tail 

 coverts sooty gray, slightly darker on the crown, somewhat paler on 

 the lower hindneck ; a brownish gray band across lower foreneck and 

 upper breast; a buffy white band across hindneck; under surface, 

 except as described, white. 



