| OCR Text |
Show 1888.] DR. H. GADOW ON THE REMIGES OF BIRDS. 657 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 11th quill is very tiny indeed, or it is altogether absent. In this case, however, the upper covert is present as an apparently supernumerary feathe.r, 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 Cypselus, and a very degenerate condition, as in many of the so-called Oscines novempennatse. In the latter birds it was first properly recognized as a true primary by Baird, in his ' Review of American Birds.' In all cases the reduction from 11 to 10 primaries 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 percnopterus, for instance, the 11th quill is more than 4 centim. long and quite white like the lower wing-coverts, not black like the upper coverts and the other primaries. The same is the case with Grus leucogeranus. The terminal or 11th 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 stiff 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 substitute for the latter. Passeres. It is hardly necessary to mention that there are numerous transitional 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 Alaudidse belong to Group D according to the state of their primaries ; Lanius minor differs strikingly from all the other Laniina3. 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 Sturnidee. 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 Alaudidse 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 |
