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Show 1887.] OF THE WINGS OF BIRDS. 347 form the humerals (penna humerales), the "parapteron" of Nitzsch (Plate X X X . fig. a, h). On the ventral surface next the median coverts are three row of feathers (Plate X X X . fig. b, y), the tectrices minores of the lower surface, which are but scantily represented on the manus. A fairly well-marked space' running the whole length of the cubitus separates these from two to three rows of feathers which run from the wrist to the elbow; and then are continued on the arm, where they become largely developed, 6 to 8 feathers (Plate X X X I. fig. b, ax) forming the axillaries (hypopteron of Nitzsch). This row may be termed, when distinct as here, an axillary row, though really forming part of the minores; in some birds there is no space separating them, and then they are confluent. The t. minores of the upper and lower surface generally correspond, both producing special developments, the " humerals " and " axillars." The next group of feathers (Plates X X X . & XXXI., p) grow along the posterior border of the wing, extending from the proximal end of the patagium to the end of the manus. On the dorsal surface they soon approach the minores and become confluent with them, though distinguishable in fresh undisturbed plumages by difference of overlap. On the ventral surface the patagial space is large, and separates them well from the minores. The feathers growing from the edge of the patagium are sufficiently elongated to cover this deficiency. At the wrist they become confluent with the other series and are continued on the hand. This group of feathers is common to both surfaces of the wing, insomuch as they form on the anterior border a shelving series, giving a clean finishing edge to the anterior margin of the wing. They are best termed marginals (tectrices marginales). The feathers of the pollex, pluma pollicis (" alula," "ala spuria"), are partly of this series and of the minores ; and by specialization produce four small quill-feathers with coverts, which lie closely embracing the dorsal part of the anterior border of the manus, and hiding many of its lesser coverts. The table at the end of this paper (p. 355) shows the relation of the nomenclature adopted above with that of Sundevall, and the ordinary nomenclature such as that found in Coues's Key to N . A. Birds. All birds' wings (except the Penguins) are directly referable to the type just described. It contains all the elements which occur in the wing, and it is by the specialization and suppression of these parts that the different'wing-forms have been derived, at any rate among Carinates, the Ratite wing being more primitive in structure. Some Modifications of the Wing. The remiges of the manus show a remarkable constancy both in number and°position, for (with the sole exception of the Penguins) the first digital always lies upon the phalanx of digit in., its end restin°- upon the metacarpophalangeal articulation; the middigitals are always constant in position, so are the predigitals. On the metacarpus are six feathers always except in Flamingoes, Grebes, and 1 This is especially well seen in the Grebes. |
