458 



NATURAL HISTORY OF BIRDS. 



OuDEU XVTTI. — PASSERES. 



This order comprises in round numbers say six thousand species, or more than )ial£ 

 the number of all the known birds. In the foregoing pages of this volume, conse- 

 quently, we have dealt with a less number of species than this oi'der alone contains. 

 The great majority of the Passerine species, however, are so closely allied that it is 

 only in catalogues and nominal lists that they take up the greatest space ; while here, 

 where we have to consider the forms according to their biological and morphological 

 features, the jiresent order will receive a treatment commensurate with the imjjortance 

 of the group in these respects, but not with the number of the species. 



There seems to be no single character by which the Passeres, as here and most 

 commonly defined, can be sej)arated from all the rest of the birds. Hence the only 

 characteristic which can be formulated in a few words is that they possess a number 

 of characters which are not combined in the same way in any bird included in the 

 foregoing orders. It is especially among the Picarians tliat we find forms wliich 

 apj)roach the Passeres very closely in some of their characters, while, on the other 

 hand, a few generalized Passerine birds have retained some ancestral peculiai'ities 

 which link them to the grouj)S below. 



We have seen that legithognathism is no exclusive character; in most Passeres the 

 manubrial process of the sternum is bifurcate, but it is so in some liigher or passeri- 



form Picarians ; the hind 

 margin of the breastbone 

 has mostly only two notch- 

 es, but in a few has four, 

 and in some Picaria; has 

 also only two ; the Passeres 

 have ca?ca and no tuft to 

 the oil-gland, but many Pi- 

 carians are similarly charac- 

 terized ; tlie Passeres have 

 a peculiarly specialized ar- 

 rangement of the wing-cov- 

 erts, a feature already noted 

 „ on a previous pacre when we 



Fio. 228. — Diagram of the elboir-mnscles In [A) Ictrrua and (B) Menura; . , , \ ^ 



milBcles with longitmliii:il. tciiUoiis with tr.insversp, lines; fc, biceps ; nnW, Said tliat WOOdpeckcrS and 



extensor nietacurpi railialis lonRusi ; /j, liuinems ; jt, shouUler ; at, second- ... , - 



nry romiges ; (, triceps; tph, tensor putagii brevis ; Ipl, tensor patagii Some allied loi'lllS present 



the same kind of specializa- 

 tion. The schizo])elmous arrangement of the deep plantar tendons would have been 

 an excellent distinction but for the fact tliat the hoopoes are also schizo])elmous, while 

 the Eiiryl:iiniida>, which are otherwise true Passeres, have the flexor hallucis attached 

 to the perforans digitoruni by means of a strong vinculum, making them desmopelmous. 

 Another myological feature which is ])ecidiar to the Passeres inasmuch as it does not 

 occur in other birds, though not in all Passeres, is the distal insertion of the tensor 

 patagii brevis, a muscle which h:is already been mentioned under the head of the 

 Micropodoide*. Being obliged to treat of this character more in full, we shall try 

 to use Professor Garrod's own words whenever possible. 



ISS^WW 





