1887.] OF THE WINGS OF BIRDS. 347 



form the humevals (pennce humerales), the "parapteron" of Nitzsch 

 (Plate XXX. fig. a, h). On the ventral surface next the median 

 coverts are three row of feathers (Plate XXX. fig. b, y), the tec- 

 trices minores of the lower surface, which are but scantily repre- 

 sented 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 elljow ; and then are continued on the arm, 

 where they become largely developed, 6 to 8 feathers (Plate XXXI. 

 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 sepa- 

 rating 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 XXX. & XXXI., /i) 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 over- 

 lap. 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. Tbey are best termed marginals (fecirices 

 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 tlie 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 directiv 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 fiosition, for (with the sole exception of the Penguins) 

 tiie first digital always lies upon the phalanx of digit iii., its end 

 resting upon the metacarpo-phalangeal articulation ; the middigitals 

 are always constant in position, so nve the predif/itals. On the meta- 

 carpus are six feathers always except in Flamingoes, Grebes, and 

 ^ This is especially well seen in the Grebes. 



