THE HEAD. 45 



of the nose, and divided into two surfaces by a slightly vertical and sinuous 

 crest that affords attachment to the maxillary turbinated bone : the anterior 

 surface, which responds to the middle meatus of the nasal fossa, shows the 

 lower orifice of the osseous lachrymal canal continued by a fissure to the lower 

 extremity of the bone ; the posterior surface belongs to the inferior meatus. 

 This face presents, near its inferior border, a large vertical apophysis, the 

 palatine process, which offers an anterior slightly concave face, forming the 

 floor of the nasal fossae; a posterior face, furrowed by small fissures, 

 perforated by fine openings, and traversed along its length by a somewhat 

 wide groove, the palatine fissure, which commences above at the -lower orifice 

 of the palatine canal. The internal border of this process articulates with 

 the analogue of the palatine process of the opposite side. 



Borders. The anterior, thin and convex, is divided into two parts : an 

 inferior, which is mortised to receive the external border of the nasal bone 

 and the external process of the premaxillary ; and a superior, cut in a wide 

 bevel at the expense of the external plate, to respond to the lachrymal and 

 zygomatic bones. The external border is very thick and hollowed into six 

 large quadrilateral cavities, named alveoli, in which are implanted the molar 

 teeth. Above the last alveolus it forms a rugged eminence designated the 

 alveolar tuberosity ; below the first it becomes thin and sharp, and constitutes 

 part of the interdental space which separates the molar from the incisor teeth. 



Extremities. The superior is the thickest, and represents a smooth 

 rounded protuberance, into the interior of which the maxillary sinus is 

 prolonged. Above and within this eminence, is a wide and deep excavation, 

 in the formation of which the palate bones participate. This is the 

 maxillary hiatus, situated directly opposite the orbital hiatus. At the 

 bottom of this cavity is seen the nasal foramen, as well as the upper orifice 

 of the supermaxillo-dental and the palatine canals. The nasal foramen 

 belongs to the palate bone and enters the nasal cavity. The super- 

 maxillo-dental or infra-orbital canal traverses the maxillary sinus in passing 

 above the roots of the molar teeth, and terminates by two branches : one, 

 short and wide, which opens on the external surface of the bone, on a 

 level with the third molar ; the other, very narrow, continues the course of 

 the canal in the thickness of the bone, and is prolonged by several small 

 very fine branches into the premaxillary bone. The palatine canal, channeled 

 between the supermaxillary and the palate bone, extends from the maxillary 

 hiatus to the palatine fissure. 



The inferior extremity presents a cavity which forms the alveolus of the 

 tusk by uniting with a similar space in the premaxillary bone. 



Structure and development. This bone is developed from a single nucleus, 

 and is the more spongy, particularly towards the alveolar border and the 

 superior extremity, as the animal is young. 



2. Premaxillary, Intermaxillary, Anterior Maxillary or Incisive Bone. 



This bone occupies the inferior extremity of the head, and is composed of 

 a thick prismatic portion, lengthened superiorly by two long processes. 



Thick portion or base. This presents a solid mass with three faces : an 

 external or labial, smooth and convex ; an internal, denticulated for union 

 with the opposite bone, and traversed from before to behind by an inflexed 

 fissure, which forms, with an analogous one in the other premaxillary, 

 the incisive canal or foramen ; the third or posterior, also called the buccal, is 

 slighty concave, and shows the continuation of the palatine fissure, which 



