The =body= (Corpus mandibulæ) is the thick anterior part which bears the incisor teeth. It presents two surfaces and a border. The =lingual= or =superior surface= (Facies lingualis) is smooth and slightly concave; during life it is covered by mucous membrane, and the tip of the tongue overlies it. The =labial= or =mental surface= (Facies mentalis) is convex and is related to the lower lip. It is marked by a median furrow which indicates the position of the primitive symphysis mandibulæ. The curved =alveolar border= (Limbus alveolaris) presents six alveoli for the incisor teeth, and a little further back two alveoli for the canine teeth in the male; in the mare the latter are usually absent or small. The =rami= (Rami mandibulæ) extend backward from the body and diverge to inclose the =submaxillary space= (Spatium mandibulare). Each ramus is bent so as to consist of a horizontal part (Pars molaris) which bears the lower cheek teeth, and a vertical part (Ramus mandibulæ) which is expanded and furnishes attachment to powerful muscles; the term =angle= is applied to the most prominent part of the curve. The ramus presents two surfaces, two borders, and two extremities. The =external surface= is smooth and slightly convex from edge to edge on the horizontal part; at the junction with the body it presents the =mental foramen= (Foramen mentale), which is the external opening of the mandibular or inferior dental canal. On the vertical part it is somewhat concave and presents a number of rough lines for the attachment of the masseter muscle. The =internal surface= of the horizontal part is smooth, and presents a shallow longitudinal depression in its middle; above this there is often a faint mylo-hyoid line for the attachment of the muscle of like name. At the lower part of the junction with the body there is a small fossa for the attachment of the genio-hyoid and genio-glossus muscles. On the vertical part the surface is concave, and is marked in its lower and posterior part by rough lines for the attachment of the internal pterygoid muscle. In front of its middle is the =mandibular= or =inferior maxillary foramen= (Foramen mandibulare), which is the posterior orifice of the =mandibular= or =inferior dental canal= (Canalis mandibulæ). The canal curves downward and passes forward below the cheek teeth, opening externally at the mental foramen; it is continued into the body of the bone as a small canal (Canalis alveolaris incisivus), which carries the vessels and nerves to the incisor teeth. The =superior= or =alveolar border= forms anteriorly part of the interalveolar space; here it is thin. Behind this it is thick and is excavated by six alveoli for the lower cheek teeth. Behind the last alveolus it curves sharply upward and is narrow and rough. In the young foal there is commonly a small alveolus for the vestige of the first premolar (“wolf tooth”) close to the first large one. The =inferior