THE EYE 



773 



some resemblance to an anchor. The gland of th(> 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 smalhn- excretory ducts. The subconjunc- 

 tival tissue of the third eyelid contains lymi)h nodules, which are specially numer- 

 ous on the bull)ar side. 



Upper eyelid 



Third 

 Caruncidn Incrini 

 Internal canthus 



Lower eyelid 



Fig. 583. — Eye of Ox. (.\fter EUenberger-Bauni, Anat. fur 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). There are six to eight larger excretory ducts and several smaller ones. 

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

 terminal jxirt 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. 



Corijunctivii hulbi 



Sclera 



Third eyelid 

 Carimcula Incrimalis 



Cornea 



Pupil 



Fig. 584. — Left Eyeball of Ox in situ, Exterx.^i- \'if.w. 

 19, Orbital fat. (After EUenberger-Baum, Anat. fur Kiuistler.'> 



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



The a\-erage transverse diaineter 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. Tlie point of entrance of the optic nerve is about 2 mm. external 

 to the vertical meridian, and about 7 imn. Ix'low 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 1.0 mm. near the cornea. 



