158 



SKELETON OF THE SHEEP 



to the orbital margin than to the median line. The groove which leads forward 

 from it is often rather faint. The orbital part is deeply concave. The infraorbital 

 canal opens on the medial wall of the orbit as in the ox. The frontal sinus extends 

 backward to a transverse plane through the posterior part of the temporal con- 

 dyle, and forward to one through the anterior margin of the orbit. 



The temporal bone consists of distinct squamous, tympanic, and petro-mastoid 

 parts. The squamous part in general resembles that of the ox, but has, like that of 

 the horse, a notch through which the external acoustic process protrudes. The root 

 of the zygomatic process is perforated by a foramen which opens ventrally behind 

 the postglenoid process, in front of the chief external opening of the temporal canal. 

 The latter extends upward and backward between the petro-mastoid and squamous 

 parts and the parietal bone, and opens into the cranial cavity in front of the apex 

 of the petrous. The tympanic part includes the external acoustic process, the bulla 



Fig. 161. — Skull of Sheep; Lateral View. 

 A, Occipital bone; B, parietal bone; C, squamous temporal bone ; D, frontal bone; i?, nasal bone; F, lacrimal bone; 

 G, malar bone; Zf, maxilla; I, premaxilla; J, mandible; K, perpendicular part of palatine bone; L, hyoid bone; 1, 

 occipital condyle; 2, paramastoid process; 3, mastoid process; 4, meatus acusticus externus; 5, bulla ossea; 6, zygo- 

 matic process of temporal bone; 7, condyle of mandible; 8, coronoid process; 9, supraorbital process; 10, processus 

 cornus; 11, 11', openings of supraorbital canal; 12, ethmoidal foramen; 13, optic foramen; 14, fossa sacci lacrimalis; 

 15, bulla lacrimalis;] 16, external lacrimal fossa; 17, facial tuberosity; 18, infraorbital foramen; 19, mental foramen. 



ossea, and the muscular process; the first resembles that feature in the horse, the 

 others those of the ox, but the cavity of the bulla is undivided. The cerebral sur- 

 face of the petrous part presents the floccular fossa on its upper part, and a round 

 eminence behind the internal acoustic meatus. 



The bones of the face present, aside from the difference in size, few important 

 special features. 



In regard to the maxilla it may be noted that the junction with the lacrimal and 

 malar is less oblique than in the ox, since the facial parts of these bones are quadri- 

 lateral and not produced to a point anteriorly. The facial tuberosity and the infra- 

 orbital foramen are a little further back, and lie about over the second and fourth 

 cheek tooth respectively. The palatine sinus extends from a point opposite to the 

 first cheek tooth backward to the transverse palatine suture. The defect (in the 

 dry skull) in its nasal wall is quite small — in marked contrast to that of the ox — 



