The =sphenoid bone= is short. The cranial surface of the body presents a deep sella turcica, in front of which it rises abruptly. The high anterior part bears a central ridge (Rostrum sphenoidale), which joins the crista galli of the ethmoid. Two foramina occur on either side. Of these, the large anterior one is equivalent to the foramen rotundum, lacerum orbitale, and patheticum of the horse. The posterior one is the =foramen ovale=, which transmits the inferior maxillary nerve. The orbital wing is thick and is overlapped by the frontal in such manner as to appear externally to divide into two branches; the anterior part joins the ethmoid close to the sphenopalatine foramen, and contains a small sinus which communicates with an ethmoidal meatus. The temporal wing is small, but forms a prominent thick pterygoid crest. The pterygoid process is wide, and the pterygoid or alar foramen is absent. The sphenoidal sinus is absent in the calf and small in the adult; it communicates by one or two small openings with an ethmoidal meatus, and so with the nasal cavity. [Illustration: FIG. 89.—SKULL AND ATLAS OF OX, LATERAL VIEW. _9_, Zygomatic arch; _11_, coronoid process; _12_, supraorbital process; _13″_, paramastoid or styloid process; _13‴_, occipital condyle; _14_, parietal bone; _15_, frontal bone; _16_, squamous temporal bone; _17_, external auditory meatus; _18_, temporal condyle; _19_, orbital surface of lacrimal bone; _20_, malar bone; _21_, facial surface of lacrimal bone; _22_, nasal bone; _23_, nasal process of premaxilla; _24′_, incisor teeth; _26_, maxilla; _27_, facial tuberosity; infraorbital foramen in front of _27_; _28′_, molar part of ramus of mandible; _30_, broad vertical part of ramus; _30′_, angle of jaw; _31_, condyle of mandible; _32_, atlas; _x_, wing of atlas. (After Ellenberger-Baum, Anat. für Künstler.) ] The =ethmoid bone= has an extensive perpendicular plate. The lateral mass consists of five endoturbinals and eighteen ectoturbinals (Paulli). The largest ethmoturbinal is so extensive as to be termed a third or middle turbinal bone; it projects forward between the upper and lower turbinals. The lamina papyracea appears to a small extent externally in the pterygo-palatine fossa, forming part of the upper margin of the sphenopalatine foramen. The =interparietals= are primitively paired, but unite before birth. As already mentioned, fusion occurs before or shortly after birth with the parietals and supraoccipital. No distinct tentorium osseum is present. [Illustration: FIG. 90.—SKULL OF OX, BASAL VIEW, WITHOUT MANDIBLE.