160 



THE BONES. 



Fig. 110. 



support in the violent efforts that flight demands. The two or three last are 

 often even covered by the wing-bones, and joined to them. The inferior crest 

 of the body forms a very long spine, especially in the first vertebras. The 

 spinous processes — flat, wide, short, and consolidated with each other by their 

 opposite borders — constitute a long crest extending from the last cer\ical vertebra 

 to the bones of the wings (Fig. lOD, 7). The trans- 

 verse processes widen to their summit ; in the FovjI 

 they are nearly constantly fused with each other. 



Lumbar and sacral vertebne. — All these vertebrae 

 are formed exactly on the same type ; so that it be- 

 comes difficult, if not impossible, to fix the point where 

 the lumbar region ends or the sacral begins. At first 

 independent of each other, these vertebra?, numbering 

 fourteen, soon become consolidated with one another 

 and with the ribs ; but their primitive separation is 

 always indicated by the lateral septa, which form, on 

 their inferior face, the vestiges of the transverse pro- 

 cesses. The former are closely united to the latter in 

 the dorsal region. 



Coccygeal vertebrce. — In the coccygeal region, the 

 spine recovers its mobility. The tail of the Bird, 

 indeed, fulfils the office of a rudder in directing it during 

 flight ; and it is absolutely necessary that the vertebr* 

 which serve as a base for the steering feathers should 

 preserve their independence, so as to allow these to be 

 carried to the right, left, downwards, or upwards. 

 These vertebrje — seven in number — present spinous 

 processes which are often bifurcated, transverse pro- 

 cesses very developed, and sometimes even spines more 

 or less long on the inferior surface of their bodies. The 

 last vertebra is always the most voluminous ; it is 

 flattened on both sides, and terminates in a curved-up 

 point. 



Head (Fig. 110, f, g).— The head of the Bird is 

 small, and of a conical form. The anterior extremity 

 is elongated, and terminated by a pointed or flattened 

 beak, which allows the animal to cut the air with more 

 facility. 



Bones of the cranium. — The bones which compose 



the cranium are, as in Mammalia, an occipital, parietal, 



frontal, ethmoid, sphenoid, and two temporcds. These bones are not isolated from 



each other, excepting during early life in the shell ; and the ossifying process 



12. OS quadratum ; 13, malar bone. H, Sternum : 14, brisket or keel ; 15, episternal process ; 16, 

 internal lateral process; 17, lateral external process; 18, membrnne which closes the internal 

 notch ; 19, membrane of the exte^-nal notch, i. etc., Superior Ribs : 20, posterior process of the 

 fifth. J, Inferior ribs. K, Scapula. L, Coracoid hone. M, Furculum : m, m, its two branches. 

 N, Humerus. 0, Ulna : o. radius, p. p', Bones of carpus. Q, q'. Bones of metacarpus. R. First 

 phalanx of th° large digit of the loinq : r. second phalanx of the same, r'. Phalanx of thumb. 

 S, Hium. s'. Ischium, s". Pubis : 21. sciatic foramen : 22, foramen ovale. T, Femur, v. Patella. 

 V, Tibia. X, Fibula : y, single bone of tarsus, y. Metatarsus : 23, superior process representing 

 a united metatarsal bone ; 24, process supporting the claw. Z, etc.. Digits. 



HEAD OF AN OWL (NATURAL 

 SIZE ; POSTERIOR VIEW). 



1, Occipital foramen ; 2, single 

 occipital condyle ; 3, ptery- 

 goid ; 4, inferior articular 

 surface of the os quadratum ; 



5, anterior process of ditto ; 



6, 6, anterior face of the 

 palatine bones, forming: the 

 guttural orifice of the nasal 

 cavities; 7, posterior ex- 

 tremity of ditto; 8, zygo- 

 matic ; 9. lachrymal ; 10. 

 premaxilla ; 11, orbital pro- 

 cess ; 12, right zygomatic 

 process ; 12', zygomatic pro- 

 cess on the opposite side, 

 united to the orbital pro- 

 cess. 



