Jeffries on the Primaries of Birds. 1 63 



If we summarize the above facts we find that the number of 

 primaries of which signs can be found varies from ten to eleven 

 in Carinate birds, while many more exist in the Ratitate birds, 

 while the functional primaries vary from nine to eleven in number. 

 In regard to the primary coverts, there are for the most part one 

 less than the number of primaries, varying from nine to ten in 

 number. All the above conditions can be classed in four groups, 

 the first group containing the nine primaried birds, all of which 

 belong to the Oscines. In this group the first primary and the 

 first covert are rudimentary. The second group, containing all 

 birds with ten developed primaries and nine coverts, includes the 

 rest of the Oscines, and Piri. and I presume most of the other 

 Passerine groups. 



The third group, all those with ten primaries and ten coverts, 

 includes the Cypscti, Troc/iiti. Ardeidce, Turbinares, and prob- 

 ablv others, the young of which I have not been able to examine. 



The last group, containing those birds with eleven primaries, 

 includes the Alccdi/iidiv. Falconidce, Plot id ce^ Ciconiidiv, Phos- 

 iticopteridcr* Anatidcv, Charadriidoe, Scolopacidce* Paridce, 

 Colymbidce, Aicidce, and probably most of the other lower birds. 



Thus we see that the number of primaries does not hold con- 

 stant for the larger groups of birds, but that the higher birds of 

 the various groups show a tendency towards a reduction in the 

 number of primaries. So the reduced number of primaries and 

 coverts would seem to point to high development, but not to be 

 of use in dividing the major groups. 



The rule according to which the primaries and coverts abort 

 is interesting and of importance, since it makes it possible to 

 decide whether a •• little feather" be a primary or a covert. The 

 law is simply that the most distal one aborts first, hence a covert 

 before its primary. Hence when one "little feather" is found 

 we can tell if it be a covert, as in the Tyrannidce\ or a primary, as 

 in the Kingfishers, by seeing what the next developed feather 

 is, — in the first case a primary, in the last a covert. When there 

 are two little feathers one is a primary and the other a covert, the 

 covert being uppermost. 



The definiteness in the wing formula of birds closel} related is 

 very great, the formula for one answering perfectlv for the rest. 

 So the plan ought to be a help in determining the position of 

 doubtful birds. 



