188(3.] CUBITAL COVERTS OF BIRDS. 193 



with any conspicuously-marked Pigeon of the normal type {Columba 

 guinea, for example, fig. 14 a) on the other. The difference, to me, 

 appears both striking and significant. Perhaps I may be allowed 

 to remark that the characteristic differences between Goura and the 

 normal Pigeons are represented in the very useful series of coloured 

 illustrations now posted up outside the Western Aviary in the 

 Society's Gardens. 



In addition to the difference already noted between the true 

 Pigeons and Goura, the following points of agreement and of 

 difference between the two groups may be considered : — 



In the normal Pigeons an oil-gland is present ; but is absent in 



Goura. 

 In the normal Pigeons the tail-feathers are 12 in number ; while 



there are 16 in Gvura. 

 In the normal Pigeons the pterylosis is columbine ; and is galline 



in Goura. 

 In the normal Pigeons caeca are present ; but are absent in 



Goura. 

 In the normal Pigeons a gall-bladder is present : no gall-bladder 



in Goura. 

 In the normal Pigeons incubation lasts 16 days; but extends to 



28 days in Goura. 



In addition to these peculiarities reference may be made to the 

 bird's pheasant-like habits, to certain peculiarities of the urosacral 

 and of the caudal vertebrae, to the number of the cervical vertebrae, 

 to the absence of pterygoid processes, and to other features referred 

 to hy Prof. Huxley (P.Z.S. 1S68, p. 302) and by Prof. Parker 

 (T. Z. S. v. p. 151, 1863). Dr. Sclater (Ibis, 1880, p. 407) refers 

 to certain peculiarities of the tarsus, in addition to the differences 

 just noted, as evidence in favour of separating Goura from the 

 Pigeons. 



The main differences that distinguish the wing of the Peristeropod 

 Gallinaefrom that of the Birds of Prey have already been pointed out. 

 It remains to add that the prominence of distal overlap introduced 

 by Talegalla, Crax and its allies, becomes more accentuated in 

 Numida, and thence, through the Tetraonidee (fig. 1 5, p. 194), reaches 

 its greatest development amongst the Gallinsein the typical Pheasants. 

 A progressive increase of distal imbrication can be traced, in the first 

 stages, only in the first, or posterior, row of median coverts, then in the 

 second, and the third, and so on, until in Polyplectron all the more 

 conspicuous feathers in the closed wing of the hving bird seem to lap 

 from the proximal towards the distal side of the wing. Excellent 

 examples of the features referred to may be easil}' observed in the 

 Society's Pheasant Aviary, where Lophophorus impeyanus,Euplocamus 

 sioinhoii, Phasiunus reevesi, and Polyplectron chinquis well display 

 the feature referred to. A reference to the annexed figure of 

 Euplocanms swinhoii (fig. 16, p. 194) will serve to make the general 

 disposition clear. 



Puvo follows a slightly different pattern ; and it is a point worth 



