Till': Fli(K:s SKKI.h'TOX 11 



ciital siirliuT (»l the tynipaimin and miicr car. 'I'liis is tin; hone 

 already seen wlicii studying tlir tyinpamiiii. It transmits 

 vibrations from the tympanum to the auditory sense organ 

 encased within the auditory capsule. 



The margin of the upper jaw is formed in front hy the prc- 

 maxilldrics, one on either side, each of which sends a process in a 

 dorsal direction, and on the side by the majUhinj. Both pre- 

 nuixillary and maxillary bones bear teeth. 



The lower jaw is formed chiefly by the long dentariea, one on 

 each side. 



Vertebral Column. — The vertebral column is composed of a 

 series of irregular V)ones including nine elements called vertebriT 

 and a caudal elongate bone, the urostijle. The first vertebra, 

 or atlas, is slightly modified because of its articulation with the 

 skull. Determine its peculiarities in this respect. The last 

 vertebra possesses a lateral projection (transverse process) 

 which is somewhat enlarged and serves as the attachment for 

 the skeleton of the hind limb. This vertebra is termed the 

 sacral vertebra. 



Select the fourth vertebra as a typical one for study and 

 identify the following parts: 



a. Centrum, the solid cylindrical portion of the vertebra. This 

 part is always ventral to the other parts. 



b. A'eural canal, the enclosed space or cavity dorsad of the 

 centrum and lodging the spinal cord. 



c. Neural arch, the bony portion forming the sides and roof 

 of the neural canal. 



d. Neural spine, the dorsal projection from the middle of the 

 neural arch. 



e. Transverse processes, lateral projections from the junction 

 of neural arch and centrum. 



/. Zygapophyses, cephalic and caudal projections from the base 

 of the neural arch. They serve to yoke the vertebne together. 



The Appendicular Skeleton. — This division of the skeleton 

 comprises (a) the bones of the free limbs, or those portions which 

 may be seen projecting beyond the general surface of the body, 

 and {b) the girdles which are embeddeil within the body walls 

 and with which the skeleton of the free limb is articulated. 



The pectoral girdle (shoulder girdle) completely encircles the 

 l)ody at the level of the arms. Mach half consists of two portions, 

 dorsal and ventral, which meet at the socket of articulation of 



