774 SENSE ORGANS AND SKIN OF THE OX 



The cornea is thicker than that of the horse. 

 ; The tapetum of the chorioidea is extensive at the outer side, but is a narrow 

 •strip internally. It has a metallic luster, shading from a brilliant green to a deep 

 blue; centrally it has a reddish sheen. 



The iris is usually very dark colored. The granula form a continuous series 

 of small nodules along the upper margin of the pupil and are most prominent 

 centrall}"; they are very small on the lower margin. 



The optic papilla is much smaller and is not so sharply defined on ophthal- 

 moscopic examination as that of the horse. Several relatively large retinal arteries 

 radiate from the center of the papilla to the periphery of the retina. They may be 

 seen to wind spirally around the veins, which are very large. 



The artoria centralis retina; arises from a posterior ciliary artery and divides close to the 

 optic papilla into three branches usually; of these the upper is larger than the two lateral branches. 

 The retina is more vascular than that of the horse; it has a round area centralis at the inner side, 

 which is continued outward by a narrow strip of a similar histological structure. 



The vitreous body is less fluid than that of the horse. 



THE EAR 



The external ear is inclined outward. The middle part is much wider and less 

 curved than in the horse. The apex is also wide and does not curve forward. 

 The lovver part of the anterior border is l)ent backward and bears long hairs. The 

 posterior border is thin and is regularly convex, except below, where it is indented. 

 The opening is wide and the concave surface presents four ridges; the convex 

 surface presents corresi^onding depressions. The styloid process of the conchal 

 cartilage is short and blunt. The edges of the annular cartilage are in contact at 

 the inner side and the upper border is notched externally. The scutiform cartilage 

 is a very irregular quadrilateral plate; it is situated on the lateral aspect of the 

 cranium with its concave surface in contact with the fat and temporalis muscle. 

 The osseous external auditory meatus is directed practically straight inward; it is 

 about twice as long as that of the horse, and tapers very gradually from without 

 inward. The chief special characters of the auricular muscles are as follows: 

 (1) The scutularis blends with the frontalis muscle. The interscutularis arises 

 from the base of the processus cornu (or the corresponding area in polled cattle) 

 and from the frontal crest. (2) The cervico-scutularis arises from the posterior 

 surface of th(^ cranium below the frontal eminence, and receives slips from the 

 parieto-auricularis and cervico-auricularis superficialis. (3) The zj^gomatico- 

 auricularis and scutulo-auricularis superficialis inferior are fused. (4) The scutulo- 

 auricularis superficialis superior is distinct from the interscutularis; it arises from 

 the superficial face of the scutiform cartilage. (5) The cervico-auricularis super- 

 ficialis arises from the ligamentum nuchse and ends on the convex surface of the 

 conchal cartilage. (6) The parieto-auricularis arises from the nuchal surface of 

 the frontal bone, the adjacent part of the parietal bone, and the ligamentum nuchse; 

 it is inserted below the preceding muscle. (7) The scutulo-auricularis superficialis 

 accessorius arises from the superficial face of the scutiform cartilage and is inserted 

 by a round tendon into the anterior part of the convex surface of the conchal car- 

 tilage. (8) The cervico-auricularis profundus minor consists of two fasciculi; the 

 inner, narrow part is deep red in color, and arises from the fascia of the cervical 

 muscles external to the occipital attachment of the ligamentum nucha?; the outer, 

 wider part is pale, and arises beneath the cervico-auricularis superficialis, indirectly 

 from the scutiform cartilage. The two unite and are inserted into the lower aspect 

 of the base of the conchal cartilage. (9) The scutulo-auricularis profundus minor 

 arises from the tem])oral crest above the external auditory meatus and is inserted 

 into the anterior part of the deep face of the scutiform cartilage. 



