OCR Text |
Show 1887.] OF THE WINGS OF BIRDS. 349 feathers, in their undisturbed primitive conditions. Sundevall mentions that there are generally one or two extra major coverts connected with the cubital series, of which the feather I in his figures (the median covert here under consideration) is one. The other he does not mention (S. p. 414, par. 2). Really there are no extra coverts at all, unless the fifth cubital coverts in the aquincubital condition of the wing are so considered. In the Duck (Plate XXXII. fig. 8) it is seen that the larger feather (1"), which at first sight appears to represent the major covert, is really the median covert in front of the remex in the undisturbed quincunx series; the little feather (1') underneath being the real major covert. In this wing the two feathers have not become so closely attached to the first metacarpal as is the case in some other birds, example the Golden Eagle, Barn-Owl, & c (Plate XXXII. fig. 6). Here the relations are more apparent; the major covert is small and rudimentary, but bears the same relation the other major coverts do. The median covert is a fairly large feather, which crosses the metacarpals at a considerable angle. In the Duck the median covert of metacarpal 2 is suppressed, in the Eagle it is present (2", fig. 6). The Grebe, with seven metacarpals, shows similar modifications at the wrist-joint (Plate XXXII. fig. 7). In many birds (e.g. Passerines) the major covert altogether disappears, the median covert is large, and takes its place, lying across the metacarpals at a considerable angle, and causing the suppression of the next one or two medise (Plate XXXII. fig. 9). The remaining feather-tracts undergo modifications in different groups, which are generally of more or less minor importance. The axillars and humerals vary in their development in different groups, in the Passerines disappearing almost absolutely, in all probability in connection with the relative shortness of the humerus. The marginals in many birds of this group are much elongated on the ventral side and cover the patagium. When the wing is folded these feathers (often with the last two or three major cubital coverts) present much the appearance of the axillars in some birds. They have often been erroneously so described, whereas they have nothing whatever to do with them, the true axillars being represented by but a few semiplumes at most. The modifications of the overlap of the dorsal cubital median and minor coverts have recently been very fully worked out by Goodcbild (P. Z. S. 1886, pp. 184-203). These feathers are termed by Goodchild the "median cubital coverts;" but it is much better to confine the term " median coverts " to the row following the majores, and call the others " minor coverts." Goodchild's terms " supplementary row of median coverts" or "upper wing-coverts" and " posterior row of median coverts" are unnatural, because part of his supplementary row in the majority of cases belongs to the t. media?, and the greater and proximal part of his posterior row to the same', whereas the distal part belongs to the first row of minores (cf. his fi°-. 1, p- 186, P. Z. S. loc. cit.). His supplementary row generally means the distal t. mediae proper, and sometimes includes some of the feathers of the next two or three rows on the wrist, PROC. ZOOL. Soc-1887, No. XXIV. 24 |