" AQUINTOCTTBITALISM " liST THE BIRd's WING. 251 



broad, and the fliglit, though strong and capable of being sus- 

 tained for long periods, is not so rapid. 



It will be found that, the less the wing is used, the greater is 

 the departure from this type. The manus shortens conspicuously,. 

 and the wing takes on a rounded form, making it difficult to 

 distinguish primaries from secondaries in the outstretched wing. 

 This is well seen in the wing of Oj)istliocomus (PI. 16. fig. 2),. 

 Again, compare the wings of the Kagu, Psophia, Ocydromus, or the 

 Common Water-E-ai], with that of the more perfect Cranes ; or 

 the wings of Coua, Phce.nicophaes, and Crotophaga, Turacus. and 

 Musophaga, with that of the Common Cuckoo ; of Stringops with 

 that of other Parrots, and so on. In all, the wing-area of the 

 hand is lessened, markedly so, and the relative length of the 

 secondaries is increased, whilst the primaries and their coverts 

 grow shorter from within outwards. On discussing this matter 

 with my friend and colleague, Mr. Eugene Gates, he drew my 

 attention to the fact that this shortening and widening of the 

 wing obtains in two non-migratory Indian Duclis. 



The wings of the Rhea, Ostrich, Cassowary, and Apteryx 

 aflFord evidence of still greater retrogression, passing from a 

 relatively large wing, such as that of Rhea, in which may be 

 distinguished primaries, secondaries, and coverts*, to the vestiges, 

 more and more complete, in the Aptei*}X, Cassowary, Mpijornis, 

 Moa, and Hesperornis. 



The wings, then, both of the Batitse and the Cariuatee, show 

 that the reduction of the skeleton is soon followed by a reduction 

 in the size, and then in the number ot the remiges, and that this 

 latter takes place at the extreme distal end of the primary and 

 proximal end of the secondary series, where they become shorter 

 and shorter and finally disappear. 



* The pterylosis of the wing of lihea I hope to describe shortly. It differs 

 markedly from that of all other wings in that the dorsal coverts and remiges^of 

 the forearm are clustered together in strongly-marked obliquely-transverse rows- 

 separated by deep furrows one fi-om the other. Furthermore, there remains to be 

 settled one or two points touching the nature and homology of the x-emiges, and 

 the disposition of the feathers in the carpal region. The ventral surface of the 

 wing is bare. 



In connection with the cubital remiges, it is interesting to note that these,' iu 

 the Common Fowl, are, in the nestling, functionally preceded by their major 

 coverts. This appears to be the case also in the young Pigeon, as is well seen- 

 in PL 16. fig. 1. 



