POSTERIOR LYMPHATIC SYSTEM OF THE EYE. 335 



tion with each other (fig. 369). One of these spaces (p) is 

 situated between the sclerotic and cornea throughout the whole 

 extent of these membranes, from the ciliary body to near the 

 point of entrance of the optic nerve into the bulb. On account 

 of its investing the choroid it has been termed the pericho- 

 roidal space. In Birds it forms a kind of lacuna, resembling 

 the serous cavities in being bounded by two smooth walls. In 

 Mammals the space is usually traversed by numerous trabeculse, 



Fig. 369. 



Fig. 369. Diagrammatic representation of the posterior lymphatic 

 tracts of the eye of the Pig, with the exception of the lymphatics of 

 the retina. On the left the relation of the tendons inserted into the 

 bulb, to the ' cavity of Tenon,' t, is exhibited; on the right, the latter 

 is also shown near the insertion of the muscles. The lettering is 

 for the most part referred to and explained in the text, but in addition 

 a indicates a layer of fat between the retractor muscle and the supra- 

 vaginal space ; c, conjunctiva ; ra r, musculi recti ; m retr, musculus 

 retractor bulbi ; v, external or fibrous sheaths of the optic nerve. 



which in some instances, as in the eye of Man and of the Dog, 

 may form quite a plexiform tissue, that has been named the 

 membrana suprachoroidea. The portion of this tissue which 

 remains attached to the sclerotic after detachment of the choroid 

 has also been termed the lamina fusca. The peculiarity of struc- 

 ture of the plexiform tissue of the suprachoroidea is that it is 



