8 



SKELETON 



CHAP. 



posterior portion, where they often take the form of prolonga- 

 tions, the extremities of which occasionally meet and enclose 

 what are called fcnestrae ; but these are un- 

 important when compared with the features pre- 

 sented by the anterior part. 



4. The Pectoral Arch, or 

 Shoulder- Girdle, consists of 

 >. three pairs of bones, the 

 J^l; >., Coracoids, the Scapulae 

 \Vv\ "'"'.;.. or Shoulder-blades, 

 '"--,^ and the Clavicles 

 or Collar- 



bones, the last two usu- 

 ally coalescing in the 

 median line into a 

 V-shaped or U-shaped 

 Furcula (the well-known 

 "Merry-thought"); but 

 in some groups, as 

 certain Parrots, the 

 clavicles are practically 

 absent, while in others. 



Fig. 3. Skeleton of the Lirahs and Tail of a Carinate ^^ Several Owls, they do 



Bird. (The skeleton of the body is indicated by not Unite. The furcula 

 dotted lines.) F, digits; Fi, fibula; HW, carpus; . n i 



MF, tarsometatarsns ; MH, carpometacarpus ; OA, otten OSSlheS hrmly 



humerus ; OS, femur ; Py, pygostyle ; K coracoid ; ^yith the anterior por- 

 Rd, ulna ; Sch, scapula ; St, sternum, with its keel . i n 



(CV) ; T, tibiotarsus ; Ul, radius; Z, Z^, digits of tion of the keel, and in 



foot. (From Wiedersheim.) Frerjata, Diclus and the 



Puititae, the coracoids and scapulae are fused together. 



5. The Anterior Limbs, or Wings, are composed of the 

 Humerus, or upper arm - bone, the Ulna and Eadius (mak- 

 ing the fore-arm), the Carpus or wrist, the Metacarpus and 

 Digits, corresponding with the hand and fingers. The first of the 

 three metacarpals bears the Pollex, or thumb, with one or two 



