=Articulations of the Mandible.=--In man the two halves of the mandible are united craniad, so as to form a single bone. In the cat the two halves are separate, but articulate closely at the =symphysis menti= by a thin interarticular cartilage. The articulation of the mandible at the mandibular fossa of the temporal is covered with a close =articular capsule=. The mandibular fossa is lined with cartilage. A slender ligament passes from the angular process of the mandible caudad to the external auditory meatus, being attached to the latter about 8 millimeters from its medial end. This is the =stylomandibular ligament=. V. BONES OF THE THORACIC EXTREMITIES. =Scapula= (Figs. 44 and 45).--The scapula may be described as a flat triangular bone with one angle rounded. It lies beneath the muscles on the lateral face of the thorax near its cranial end. From its lateral surface there projects a flat ridge (Fig. 44, _g_), the =spine= of the scapula. The ventral end of the ridge is free as a curved process, the =acromion= process (Fig. 44, _j_). [Illustration: FIG. 44.--SCAPULA, LATERAL SURFACE. FIG. 45.--SCAPULA, MEDIAL SURFACE. _I_, fossa supraspinata; _II_, fossa infraspinata; _III_, fossa subscapularis; _IV_, fossa for teres major. _a_, vertebral border; _b_, coracoid border; _c_, glenoid border; _d_, glenoid angle and fossa; _e_, coracovertebral angle; _f_, glenovertebral angle; _g_, spine; _h_, tuberosity of the spine; _i_, metacromion; _j_, acromion; _k_, supraglenoidal tubercle; _l_, incisura scapulæ; _m_, coracoid process; _n_, groove indicating portion of spine; _o_, _o′_, ridges for attachment of muscle-fibres.] The ventral angle of the scapula (_d_), the =glenoid= angle (lateral angle of human anatomy), is much heavier than the others and bears a concave, pear-shaped articular facet, the =glenoid fossa=, for articulation with the humerus. The border with which this angle is more nearly continuous may be called the =glenoid= border (_c_) (axillary border of human anatomy). Near the narrower cranial end of the glenoid fossa is a small curved projection of the bone, the =coracoid= process (Fig. 45, _m_). The border upon which it lies is the =coracoid border= (_b_) (superior border of human anatomy). The third border is turned toward the vertebral column and is the =vertebral border= (_a_). The angle between the glenoid and vertebral borders is the =glenovertebral= angle (_f_) (inferior angle of human anatomy), and that between the coracoid and vertebral borders the =coracovertebral= angle (_e_) (medial angle of human anatomy).