Letters, Extracts, Notices, t$c. 129 



an excellent observer of the habits of birds in their native 

 haunts, had that same morning (Dec. 28, 1881) narrated to 

 Mr. Ridgway how, when he was in Florida, he had noticed 

 that the young of Ionornis martinica actually put these claws 

 to practical use by holding on to twigs in climbing out of 

 their nests, and sometimes even suspended themselves as 

 Bats do/' These claws are large in the Californian Condor, 

 and it would be interesting to know whether the young of 

 the Cathartidae put them to similar uses. 



Yours &c, 



R. W. Shufeldt. 



United States National Museum, 



Washington, November 22, 1889. 



Sir, — In the last number of ' The Ibis ' Mr. J. H. G-urney, 

 Jun., remarks (p. 572), that Colymbus aclamsi " is only dis- 

 tinguished from ... C. glacialis by the white colour of the 

 bill and a slight difference in its shape." Having on various 

 occasions compared specimens of the two birds and noted 

 other differences, I desire to say that in true C. aclamsi the 

 whitish colour of the bill is the least important distinctive 

 character, since C. glacialis occasionally has a more or less 

 light-coloured bill. In C. adamsi the exposed culmen is 

 longer than the tarsus, while in C. glacialis it is shorter : in 

 C. adamsi the head and neck are glossed with violet-blue, and 

 the white spots on the scapulars are decidedly longer than 

 broad ; while in C. glacialis the head and neck are glossed 

 with green, and the white spots on the scapulars about as wide 

 as they are long. These differences are quite constant, and 

 therefore young birds may readily be distinguished by the 

 comparative length of exposed culmen and tarsus. (Cf. 

 1 Manual of North-American Birds/ p. 7, where, however, by 

 an accidental transposition of the words " shorter " and 

 " longer," in paragraphs c 1 and c 2 respectively, the relative 

 length of culmen and tarsus in the two species is made to 

 appear exactly the opposite of what is actually the case.) 



Yours &c, 



Robert Ridgway. 



ser. VI. — VOL. II. 



