18b8.] DR. H. GADOW ON THE REMIGES OF BIRDS. (>o7 



unfrequently it is shorter and weaker than its upper, often very 

 stiff covert. In some birds, e. g. in certain Fulicariae and in the 

 Passeres, the 1 Itli quill is very tiny indeed, or it is altogether absent. 

 In this case, however, the upper covert is present as an apparently 

 supernumerary feather, provided that the 10th quill is not likewise 

 much reduced. The 10th primary shows every intermediate stage 

 between the largest possible development, as in Larus and Ci/pselus, 

 and a very degenerate condition, as in many of the so-called Oscines 

 novempennatse. In the latter birds it was first properly recog- 

 nized as a true primary by Baird, in his ' Review of American 

 Birds.' In all cases the reduction from 11 to 10 [)rimaries is 

 brought about by the reduction at the terminal end of the wing. 



The reduced terminal quill occasionally assumes the shape and 

 coloration of its lower covert, and does not agree with the other 

 primaries nor with its upper covert, as one might be predisposed to 

 think would be the case. In Neophron j^ercnopterus, for instance, the 

 1 1th quill is more than 4 centim. long and quite white like the lower 

 wing-coverts, not black like the upper coverts and the other prima- 

 ries. The same is the case with Grus leucogeranus. The terminal 

 or 1 1th quill of Oriolus is very small, and yellow like the lower wing- 

 coverts. In Rupicola it is very tiny, reddish like the lower coverts, 

 and hidden by a very stiiF upper covert of 4 centim. in length. This 

 is one of many cases in which the 11th upper covert is longer and 

 much stronger than its primary quill, so that it even acts as a sub- 

 stitute for the latter. 



Passeres. 



It is hardly necessary to mention that there are numerous transi- 

 tional stages which connect the four groups A, B, C, D into which 

 Wallace has divided the Passeres. There can be no doubt about 

 the fact that the reduction of the 9th and 10th primaries has taken 

 place in the various families independently ; identical conditions of 

 the terminal quills do not therefore necessarily indicate relationship. 

 Some Alaudidee belong to Group D according to the state of their 

 primaries ; Lanius minor differs strikingly from all the other Laniinae. 

 The Vireoninae are probably now in an unsettled state, to judge from 

 the variable relative size of their terminal quills. Heteralocha does 

 not agree with the Sturnidse. 



The gradual diminution of the 10th primary can well be studied 

 in Group D. 



In some cases there might be some doubt whether the little terminal 

 feather in question is in reality a primary, but this can easily be 

 settled by the presence of the corresponding upper covert. Moreover 

 there are many cases in which this prima/y is still longer than its 

 covert. When the 10th or 11th quill is much shortened, the 

 corresponding lower covert is absent in the Passeres. The Alaudidae 

 prove that the 10th quill is capable of being shifted dorsalwards, so 

 that it becomes enclosed between the outer vane of the 9th primary 

 and the 10th upper covert, instead of being situated freely visible 

 below and in front of the 9th primary ; when seen from below, it is 



