350 MR. R. S. WRAY ON THE MORPHOLOGY [Apr. 5, 



which appear, as a consequence of folding superficially, to form a series 

 with them ; it is sim])ly 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 tlieir insertion, and 

 remembering the conditions of folding which mnst occur at the wrist, 

 the observations of Groodchild 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 surface * show a great 

 variety of modification, which if systematically worked out would I 

 believe furnish valuable characters. But jiractically 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 Dueldinff'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 fore- 

 shadowing 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 ])arallel to this. The way the plumules of the Duckling are 

 shed is very interesting; at the base of theplumule 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 i 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 Ratitae. 



The wings of the Ratitae 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 



^ There are some yery good figures of the lower surface of the wing of 

 certain Hawks in the' Zoologist,' 1880, p. 273, pis. 2 and 3. 



