120 PTERYLOGRAPHY. 



CHAPTER VII. 

 WADING BIRDS (Grallce). 



IN this group of birds, which includes many species, there prevails a considerable difference 

 of pterylosis, as, indeed, would appear probable from the differences in the external forms of its 

 members. Hence we can hardly indicate any exclusive pterylographic characters. With the 

 following equivalent group, that of the Swimming Birds, it agrees in the presence of down- 

 feathers not only on the spaces, but also among the contour-feathers. This general law for all 

 aquatic birds appears to be subject only to a single exception (in Otis), although many differences 

 are met with as regards the size and closeness of the down-feathers, especially on the spaces. I 

 found the down most scanty on the spaces of Dicholophus, and densest in Fulica. With this the 

 constant presence of the after-shaft on the contour-feathers appears to be in harmony, and 

 its universal occurrence (except in Palamedea cornuta and Podoa) seems especially to furnish a 

 pretty certain distinction of the Wading Birds from the Natatores, in which it is wanting in whole 

 families (e.g. the Unguirostres) . Although in some members of the present family it may be 

 sometimes very small and delicate, as, for example, in Palamedea, Grus, and Fulica, it is pro- 

 bably deficient only in the two birds above mentioned, in which I could not detect it at all ; in 

 many cases, as in Otis, it is very large, and but little inferior to that of the Gallinacese. I always 

 find it to be largest on the feathers of the inferior tract, especially in the region of the breast ; it 

 is smaller on the feathers of the anterior part of the dorsal tract, and smallest on the hinder part of 

 the latter. Moreover, the down-feathers also possess an after-shaft, when there is an after-shaft on 

 the contour-feathers. With regard to the form of the tracts, no general statement can well be 

 made; I remark only that the lumbar tract is never deficient, and that the dorsal always encloses a 

 space, at least on certain parts of its extent, but is not always interrupted or furnished with a gap- 

 The inferior tract is very variable. Usually its bands are narrow, and in one genus (Ardea) pro- 

 bably the narrowest in the class of Birds ; nevertheless, a great breadth, especially of the pectoral 

 portion, also occurs, and in one instance (in Palamedea) even an almost uninterrupted plumage. 

 The oil-gland is in general large, with a short mamilla, and furnished with a circlet of feathers. 

 This is wanting only in the genus Dicholophus ; but the entire gland is regularly missing in Otis. 

 Sometimes several orifices are visible in each -half of the mamilla, for example, in Grus, Ciconia, 

 and Anastomus. The number of remiges varies between twenty and thirty-six ; on the pinion 

 there are usually ten, sometimes (as in the Storks and Flamingoes) eleven. The tail contains very 

 various numbers of rectrices ; at least ten (in Parra, Cancroma, and some of the Bitterns, but in 

 the latter also eleven or twelve), usually twelve, rarely fourteen (Phcsnicopterus, Fulica), or eighteen 

 (Podoa), in Otis always twenty, and in a species of Snipe (Scolopax stenoptera) as many as 

 twenty-six the greatest number that occurs in any bird. 



