516 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Exposed culmen about as long as middle toe, without claw; depth 

 of bill at base more than half the length of exposed culmen, but 

 decidedly less than length of gonys; culmen gradually curved from 

 the base, more decidedly so for terminal third; gonj^s straight, 

 decidedly shorter than length of maxilla from nostril; maxillary 

 tomium gently but decidedly concave for most of its length, the 

 rictal portion abruptly deflected; mandibular tomium strongly arched, 

 but not angulated, basally; tip of maxilla acute, without trace of 

 notch. Nostril wholly exposed, rather large, broadlj^ oval or nearly 

 circular, the surrounding membrane broadest above and behind. 

 Rictal bristles inconspicuous. Wing moderate, rounded (seventh and 

 sixth primaries longest, ninth intermediate between fourth and third), 

 the primaries exceeding secondaries by less than length of exposed 

 culmen. Tail about equal to length of primaries from tips of longest 

 primary coverts, slightly rounded, the rectrices rather broad. Tarsus 

 about one and a half times as long as exposed culmen, its scutella dis- 

 tinct; middle toe, with claw, decidedly shorter than tarsus; lateral 

 toes about equal, their claws reaching to base of middle claw; hallux 

 about equal in length to lateral toes, but very niuch stouter, its claw 

 much larger than that of middle toe. 



CoJorathon. — Adult male uniform deep (but not glossy) black, with 

 whitish margins to under tail-coverts; adult female and young olive- 

 brownish varied with dusky above, pale buily conspicuouslj- striped 

 with dusky beneath; two conspicuous deep bully or light cinnamon 

 wing-bars. 



Range. — Peculiar to Cocos Island, off Bay of Panama. (Monotypic.) 



Although this genus approaches in form of the bill the Ccerebine 

 genus Ccereba, while the adult male of the type species closed resem- 

 bles in coloration one species of the last-named genus {0. atrata), I 

 have not the slightest doubt as to its Fringilline relationships, or at 

 least its near relationship to the Galapagoan group of supposed 

 finches, among which the slender-billed Geospizce (" Cwtm^nis''^) are 

 evidently its nearest relatives. The bill is not very unlike that of the 

 Hawaiian genus Oreomyza in general form and relative size, but is 

 more decidedly decnrved, stouter at the base, and with the commissure 

 abruptly deflected basally. 



COCORNIS AGASSIZI Townsend. 

 COCOS ISLAND FINCH. 



Adult Tnale. — Uniform deep black, with the lowermost tibial feathers 

 (narrowly) and under tail-coverts (broadly) tipped or terminally mar- 

 gined with bufly white; maxilla dusky, paler on tomium, mandible 

 mostly pale brownish; legs and feet brownish black; length (skin), 

 124.46; wing, 68.07; tail, 43.43; exposed culmen, 13.9Y; depth of bill 



