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Show 350 MR. R. S. WRAY ON THE MORPHOLOGY [Apr. 5, which appear, as a consequence of folding superficially, to form a with them ; it is simply accommodation, and is only very striking when the wing is examined in the folded condition, as most of his were. Grouping the feathers according to their insertion, and remembering the conditions of folding which must occur at the wrist, the observations of Goodcbild give the most complete view of this subject we have. The Passerine birds possess only the single row, t. media, the minores being completely absent (S. p. 415, cf.); this is characteristic of them, and goes along with a very scantily feathered ventral surface. The median and minor coverts of the lower surface1 show a great variety of modification, which if systematically worked out would I believe furnish valuable characters. But practically ornithologists take no account of the lower surface of the wing, and but little can be made out from ordinary skins. For skins to be of much value for studying wing-characters, some of them ought to be prepared with one wing in the extended position. Fresh wings are much the most valuable, but they are not always available. According to Sundevall the median coverts often show a tendency to disappear, which I have noticed, often they are very small. In the Passeres the row of t. majores disappears; this is recognizable by difference of overlap. The Duckling's Wing. * If the wing of a Duckling be examined when it is a mere downy appendage, of no use for flight, it will be found to be an exact foreshadowing of the flying wing. The fifth cubital remex is absent, not even a vestige of it can be found ; so we may conclude that this modification is a very ancient and deep-seated one. The plumules (down) clothing the wing are more feather-like than the adult down. In fact a Duckling's wing forms an interesting comparison with an Ostrich's or Rhea's, these wings probably never having got beyond a stage parallel to this. The way the plumules of the Duckling are shed is very interesting; at the base of the plumule the new pennaceous feather forms, grows, and begins to force its way out from the skin. The plumule remaining attached by its base to the tip of the new feather is carried out away from the skin about | to | inch, then the connection becomes very slight, and soon the plumule is lost. This forms an analogous parallel to the shedding of milk-teeth, the plumule being retained till the new feather can functionally take its place. The Wings of the Ratitse. The wings of the Ratitse conform to the same general plan as those of the Carinatse, presenting a modification of a more generalized type, which correlates with their bony structure. In the unplucked Ostrich wing, little beyond a confused mass of feathers can be made out. The ventral surface is totally devoid of 1 There are some very good figures of the lower surface of the wing of certain Hawks in the' Zoologist,' 1880, p. 273, pis. 2 and 3. |