The horizontal portions (_a_) of the two bones are received between the maxillary bones and form the caudal and medial part of the roof of the mouth. Each is irregularly quadrilateral in form, with the caudolateral angle produced caudad into a long process which is continuous with the perpendicular portion of the bone. The lateral margin of the horizontal portion articulates over its cranial half with the maxillary bone. At about its middle a short thick =maxillary spine= (_c_) projects caudolaterad. The remainder of the lateral margin is directly continuous with the perpendicular plate of the bone. The medial margin is rough for articulation with the corresponding margin of the opposite palatine; the caudal angle of this margin projects caudad as the short =posterior nasal spine= (_d_). The caudal margin forms a free edge which bounds the choanæ; it passes laterally into the perpendicular portion. The ventral surface (Fig. 41, 8) looks into the mouth. Near the middle of its craniolateral margin are two or more small foramina (Fig. 41, _q_) which form the cranial termination of the posterior palatine canal. The dorsal surface is smooth and looks into the nasal cavity. The perpendicular or nasal portion (Fig. 33, _b_) of the palatine is thin and irregularly quadrilateral in form. It is attached by its cranial two-thirds to the dorsal surface of the horizontal portion. The outer surface is concave and looks into the orbital fossa. The inner surface is convex and looks into the nasal cavity. The perpendicular portion is marked by two foramina just craniad of the middle. The larger dorsal oval foramen is the =sphenopalatine= foramen (_e_). The smaller ventral foramen is the caudal opening of the posterior palatine canal (_f_). From this opening the canal passes craniomediad, lying in the substance of the palatine bone; it opens on the ventral surface of the horizontal portion at the small openings previously described (Fig. 41, _q_). By its cranial margin it articulates with the lachrymal bone. By its dorsal margin it articulates craniad with the orbital plate of the frontal: with the lamina papyracea at its middle, and with the body of the presphenoid caudad. The caudal half of the dorsal margin is partially divided into two lamellæ with a rough surface between them: this rough surface lies against the ventral surface of the presphenoid. The caudal margin articulates with the pterygoid portion of the sphenoid. =Lachrymal Bone.= =Os lachrymale= (Fig. 34; Fig. 39, 10).--The lachrymal bone is a thin pentagonal scale of bone filling the interval between the horizontal plate of the palatine, the maxillary, and the orbital plate of the frontal. Its outer surface looks into the orbit, its inner surface into the nasal cavity. [Illustration: FIG. 34.--LACHRYMAL BONE OF LEFT SIDE, EXTERNAL SURFACE. FIG. 35.--MALAR BONE OF RIGHT SIDE, LATERAL SURFACE. Fig. 34.--_a_, notch forming the beginning of the lachrymal canal.