Class 2. 



Div. 1. \t:iitebeate AXDIALS.— aves. 



143 



Fiff. 68.— SternHl apparatus of a 

 newly-hatchtd Cbick, 



composed originally of five pieces : one medial (fig. 68, a), of which this salient lamina 

 Pinown as the sternal crest, ridge, or keel] constitutes a part ; two triangular anterior la 

 , teral [termed costal processes] (b), for the attachment of the ribs ; 



and two forked posterior lateral (c), for the extension of its sur- 

 face ; and the greater or less degree of the ossification [that is to 

 say, obliteration] of the notches of these last, and the extent of 

 the interval which is left between them and their principal bone, 

 denote the relative amount of vigour of flight in Birds. The 

 [Eagles, Harriers, (the Falcons much more slowly, if indeed at 

 all), and some other] diurnal Birds of prey, the Swifts and the 

 Humming-birds, [the Parrots, and also the Storm-petrels,] lose, 

 as they grow old, all traces of these unossified spaces. [In the 

 Ostrich and its allies, the sternum is composed originally of only two pieces ; and the 

 number likewise varies in those Birds which possess a sternal crest.] 



The fourchette \_furcula, or " merry-thought" bone], (fig. 68, d), produced by the 

 junction of the two clavicles, and the two stout abutments formed by the [huge] 

 coracoid aphophyses (e), keep the shoulders apart, notwithstanding the opposing force 

 exerted by the action of flying ; the fourchette, in particular, is commonly more stout 

 and open, according as the flight of a Bird is vigorous.* (See fig. 67.) The 

 wing, supported by the humerus (fig, 69 a,) fore-arm 

 (J)), and hand, which is elongated, and exhibits one 

 digit and the rudiments of two [or (including the 

 winglet 0,) three] others (1,2,4) is furnished through- 

 out its length with a range of elastic quills,which greatly 

 extend the surface that resists the air. The quills ad- 

 hering to the hand are named primaries, and these are 

 [almost] always ten in numberf ; those attached to 

 the fore-arm are called secondaries, but their number 

 varies ; weaker feathers attached to the humerus are 

 styled scapularies [tertiaries ; the true scapularies 

 constituting that separate range which grows over 

 the scapulars, or " shoulder-blades"] ; and the bone 

 which represents the thumb + (o), is also furnished 

 with what are designated bastard quills, [this member 

 being generally termed alula spuria, or winglet] . Along 

 the base of the quills is a range [and sviccessive 

 ranges] of feathers named coverts [both on the outer 

 and inner surfaces of the wing, which receive corre- 

 sponding appellations to those of the quill-feathers they rig. eg.-jcr F«icon'. wing. 

 impend, as primary coverts, &c., and are further distinguished as greater, lesser, and Icastl . 



* In the in&tance of the ParrotB, some of which are birds of very 

 Btrong flight, aitbou^h the coracoids are ahrays very btout (much 

 reiietnblin^ those of the Hawks), the furcula is never strong, and is 

 peculiarly flattened, so tliat its resisting force is thus considerably 

 diminisbea. Some Parroqnels, indeed, as those small ones popularly 

 tcfiiied Lovp birds {Agrupurnis), have no .Tircula whatever; and it 

 is worthy oi ocili;^ noticed that the restricted Toucans {Rhfnnphiistna) 

 nave the clavicles separate and very short, forming small dagger- 

 khaped appeodaees, the use of which is not obvious. — £d. 



f lu the Grebe genus, eleven many of the kinging birils have thi 



first extremely minute ; and, in the Starling and some others, it is, 

 analogically speaking, wanting ; so that the number is in these 

 reduced to nine.^ — Ed. 



i As on the removal of digits, that of the thumb is found to be 

 invariably the first, the rudimentary finger above referred to is now 

 considered as analogous to the index finger of the human band : tlie 

 thumb, however, being sometimes represented by a bt.'ny spine ; 

 as the spur of a common fowl represents the first digit of the 

 foot. — Ec, 



