PASSERINE. 73 



portion that the outer angle is somewhat separated from the main stem. In a few genera, 

 e.g., Menura (Plate III, fig. 11), and Grallina, this separation reaches to the middle of the 

 wider portion, and in these cases we may regard it as a half-free lateral branch ; usually the 

 apex alone is separated (Plate III, fig. 9), but in many cases even this does not occur (Plate III, 

 figs. 7 and 13). Lastly, the ventral portion never reaches the amis, or the caudal tract behind 

 it. These characters of the two tracts occur, besides the Passerines, only in Trogon and Por/onias, 

 in which, however, other peculiarities of the pterylosis make their appearance and justify their 

 separation from the Passerines. The humeral tracts of the Passerines are small, or at least 

 narrow ; they lie far downwards, transversely across the humerus, are separated from the plumage 

 of the wing by a very large upper wing-space, and are almost always immediately, although 

 slightly, connected in front with the gular portion of the inferior tract. The lumbar tracts are 

 also small, and neither unite with the caudal tract, nor reach the knee ; but apparently are never 

 entirely wanting. The hypopterttm (or pectoral arm-winy, as it might be called) is entirely defi- 

 cient, and its region, like the inferior wing-space, is concealed by the feathers which are inserted 

 upon the margin of the great wing-membrane. At the utmost, some semiplumes are found in 

 its place. The parapterum, or the plumage on the hinder margin of the upper arm (upper arm- 

 winy], consists only of a few short feathers (Plate III, figs. 2, 8, 9, and 10). The number of 

 remiges is most commonly eighteen or nineteen among the Passerinse. When the former number 

 is present, there are only nine on the hand ; and the first primary, which is always somewhat 

 reduced in size, is in this case entirely deficient. This arrangement occurs in Procnias, Tanagra, 

 Pardalotus, Euphone, FriitgiUa, Loxia, Emberiza, Anthus, Motacilla, and some other genera. If, 

 on the contrary, there are nineteen or more remiges, ten of them are always inserted on 

 the hand, as in the other genera. Both cases, however, sometimes occur in the same genus, 

 as in Alauda. I have rarely found more than nineteen remiges ; for example, twenty in 

 Coracina and Chasmarhynchus. I have only once met with a still larger number, namely, twenty- 

 three, or even twenty-four, in Ptilorhynchus holosericeus (TEMM., PL Col. 395 and 396). 

 This variation must, however, be regarded as very small in so large a group, especially when 

 we consider how much greater it is in other families, as, for example, the Rapacious Birds. The 

 rectrices are almost invariably twelve ; the male of Menura superba has sixteen ; and Phrenotrix 

 and Edolius sometimes, and perhaps always, have only ten. Finally, the oil-gland is widened, and 

 . furnished with a very short, narrow, distinct, nearly cylindrical tip, which is rounded off at the 

 extremity, and is destitute of the circlet of feathers round the orifices ; indeed, this gland is quite 

 naked throughout the Passerines, except in the genus Cinclus, in which it bears small down- 

 feathers upon its surface. No other birds have this organ of precisely the same structure : in most 

 of them it is furnished with a circlet of feathers at the apex, or, where this is wanting, the tip 

 is gradually united to the body of the gland, so that the latter exhibits a conical form. 



The covering of the feet, which are almost invariably 1 naked from the heel downwards, also 

 presents much that is characteristic, although it by no means furnishes so constant and charac- 

 teristic a peculiarity for this group as has recently been asserted.* On the front of the tarsus 

 and the upper surface of the toes it always consists of horny half-rings. The number of these on 

 the tarsus varies from two to nine, but is more constant on the toes, inasmuch as here a small half- 



1 Only a few of the Swallows have feathered feet. 



2 In Wiegmann's 'Archiv,' 1839, i, p. 332. 



10 



