INTRODUCTION. XV 



A. PASSERES.' Hallux invariably piesont, completely iucamlifiit, sepa- 

 rately movable by specialization of the flexor haUucis longas, witli enlarged 

 base and its claw larger than that of the middle digit. Neither second nor 

 fourth toe versatile: joints of toes always 2, 3, 4, 5, from first to fourth. 

 Wing-coverts comparatively short and few ; with the exception of the least 

 coverts upon the plica alaris, arranged in only two series, the greater of 

 which does not reach beyond the middle of the secondary remiges.' Rec- 

 trices twelve (with rare anomalous exceptions). Musical apparatus [jresent 

 in greater or less development and complexity. Palate wgithognathous. 

 Sternum of one particular mould, single-notched. Carotid single (sinistra). 

 Nature highly altricial and psilopiedic. 



a. Oscines.^ Sides of the tarsus covered in most or all of their extent 

 ^vitli two undivided liorny plates meeting behind in a sharp ridge (ex- 

 cept in Alaudidm ; one of the plates imperfectly divided in a few other 

 forms). Musical apparatus highly developed, consisting of several dis- 

 tinct pairs of syringeal muscles. Primaries nine only, or ten with the 

 first frequently spurious, rarely over two thirds the length of the 

 longest, never equalling the longest. 



b. Clamatores.'' Sides of the tarsus covered with divided plates or 

 scales variously arranged, its hinder edge blunt. Musical apparatus 

 weak and imperfect, of few or incompletely distinguished syringeal 

 muscles (as far as known). Primaries ten with rare exceptions, the 

 first usually equalling or exceeding the rest. 



B. PICARI.a3.^ Hallux inconsiderable, weak or wanting, not always in- 

 cumbent, not separately movable by distinction of a special muscle, its claw 

 not longer than that of the middle toe unless of exceptional shape (e. g. Cen- 

 t7-opiis). Second or fourth toe frequently versatile ; third and fourth fre- 

 quently with decreased number of joints. Wing-covei'ts for the most part 

 larger and in more numerous series than in Pusseres, the greater series 

 reaching beyond the middle of the secondary quills (except in many Pici 

 and some others). Rectrices commonly ten (eight to twelve). Primaries 

 always ten, the first only exceptionally short (as in Pici). Musical appara- 

 tus wanting, or consisting of a muscular mass, or of not more than three 

 pairs of syringeal muscles. Palate desmognathous or Eegithognathous. 

 Sternum of non -passerine charactei', its posterior border entire or doubly 

 notched or fenestrate. Carotid single or double. Nature completely al- 

 tricial, but young sometimes hatched with down" (e. g. Caprimuhjidm). 



possess in common one single character not also to be found in other groups, nor is the colloca- 

 tion of their characters jieculiar. 



^ Corresponding closely with the Linn;ean and earlier Sundevalliaii acceptation of the term. 

 E([uivalent to the later Oscincs of Sundevall. 



^ As remarked by Sundevall, exceptions to the diagnostic pertinence of these two characters 

 of hind claw and wing-coverts taken together are scarcely found. For, in those non-passerine 

 birds, as Maplores and some fferodiones, in which the claw is enlarged, the wing-coverts are 

 otherwise disposed ; and similarly when, as in many Pici and elsewhere, the coverts are of a pas- 

 serine character, the feet are highly diverse. 



' Laminiplaiitares of Sundevall plus Alaudidm. 



* SciUcllij)! ante res of Sundevall minus Almi.dida;. 



^ Nearly equivalent to the Linnajan Piac. Equal to the late (1873) Volucres of Sundevall. 



° A polymorphic group, perfectly distinguished from Pasxcres by the above characters in which, 

 for the most part, it appro.vimates to one or another of the following lower groups, from whifh, 

 severally, it is distinguished by the inapplicability of the characters noted beyond. My divisions 



