THE EYE 



773 



some resemblance to an anchor. The gland of the third eyelid is very large— an 

 inch or more in length— and may be divided into two parts. The deep part is 

 pink and consists of loose lobules, but the much larger superficial part is more com- 

 pact. There are two large and several smaller excretory ducts. The subconjunc- 

 tival tissue of the third eyelid contains lymph nodules, which are specially numer- 

 ous on the bulbar side. 



Upper eyelid 



Third eyelid 

 Carunculn lacrimalis 

 Internal canthus 



Lower eyelid 

 Fig. 583. — Eye of Ox. (After Ellenbergei-Baum, Anat. fiir Kiinstler.) 



The lacrimal gland is thick and distinctly lobulated. It is more or less clearly 

 divided into a thick upper and a thinner lower part (Glandula lacrimalis superior, 

 inferior). Tlier(^ are six to eight larger excretory ducts and several smaller ones. 

 The naso-Iacrimal duct is shorter than in the horse, and is almost straight. Its 

 terminal i)art is inclosed between two plates of cartilage, and it opens near the nostril 

 on the outer wall ; the orifice is placed on the inner side of the alar fold of the inferior 

 turbinal, and is therefore not easily found. 



Conjunctiva hidbi 



Sclera 



Third eyelid 

 Caruncula lacrimalis 



Cornea 



Pupil 



Fig. 584. — Left Eyeball of Ox in situ, External View. 

 19, Orbital fat. (.\fter Ellenberger-Baum, Anat. fiir Kiinstler.) 



The eyeball resembles that of the horse in shape, but is considerably smaller. 



The average transverse diameter is about 42 mm., the vertical diameter 41 mm., and the 

 axis 36 mm. The angle between the axes is about 119°. 



The sclera is often more or less pigmented ; where non-pigmented it may have 

 a bluish tinge. The point of entrance of the optic nerve is about 2 mm. external 

 to the vertical meridian, and about 7 mm. below the horizontal meridian. 



The thickness of the sclera is about 2 mm. at the posterior pole, 1 mm. at the equator, and 

 1.2 to 1.5 mm. near the cornea. 



