386 



ZOOLOGY 



SECT. 



The centra articulate with one another by synovial capsules each 

 traversed by a vertical plate of cartilage, the meniscus, with a 



3t 



FIG. 1027. Columbalivia. The bones of the trunk, acr.cor. acrocoracoid ; a. <r. anti-trochanter ; 

 actb. acetabulum ; car. carina sterni ; cd. v. caudal vertebrae ; cor. coracoid ; cc. r. cervical 

 ribs ; f. trs. probe passed into foramen triosseum ; fur. furcula ; gl. cv. glenoid cavity ; il. 

 ilium; is. ischium ; is. for. ischiadic foramen; obt.n. obturator notch ; pu. pubis ; pi/;/, st. 

 pygostyle ; sop. scapula ; s. so: syn-sacrum ; st. sternum ; at. r. sternal ribs ; th. v. 1, first, 

 and th. v. 5, last thoracic vertebra ; unc. uncinates ; vr. r. vertebral ribs. 



n.ct 



central perforation through which a suspensory ligament passes 



from one centrum to the other. 



The first two vetebraB, the atlas and axis, resemble those of the 



Lizard, but have the various elements of which they are composed 



completely fused. The small size of the 

 ring-like atlas is noticeable. 



Between the last cervical vertebrae and 

 the pelvic region come either four or five 

 thoracic vertebrae (Fig. 1027) the first 

 three, when four only are present, the 

 second, third, and fourth, when there are 

 five, united into a single mass, the last 

 free. The anterior thoracic as well as 

 the posterior cervical vertebrae have the 

 centrum produced below into a compressed 

 plate, the hypapophysis, for the origin of 

 the flexor muscles of the neck. They all 

 bear ribs, each consisting of a vertebral 

 (w.r.) and a sternal (st.r.} portion, and 

 articulating with the vertebra by a double 

 head. The sternal, like the vertebral rib, 

 is formed of true bone, not of calcified 



rb 



crv 



FIG. 1028. Columba liyia. 



Cervical vertebra. A, anterior ; 

 B, posterior face. a. zyg. an- 

 terior zygapophysis ; en. cen- 

 trum ; n. a. neural arch ; p. zyg. 

 posterior xygapophysis ; rb. rib; 

 vrb.f. vertebrarterial foramen. 



