Da KNOX on the Comparative Anatomy of the Eye. 77 



i 



There are no ciliary nerves, and consequently no true iris nor 

 ciliary muscle, in the specimens I have dissected ; but, as the 

 species I have had an opportunity of examining have been but 

 few, it is not intended that these observations should apply to 

 the whole class of fishes. 



EXPLANATION OF PLATE III. 



FIG. 1. 



DISTRIBUTION of the ciliary nerves to the ciliary muscle and iris, in the eye of 

 the Cassowary. 



The choroid tunic has been cut through, where it lies over the plexus of nerves, 

 and the cavity described at page 28 of the Memoir. 



a The posterior surface of the Iris, generally called Uvea. On it may be seen the 



remains of the membrane of the Pigmentum nigrum. 

 b The Ciliary Muscle. 

 c The posterior surface of the Cornea. 

 d The cut edges of the Sclerotic and Choroid. 

 e The Ciliary Processes and Striae. 



f The external surface of the Ciliary Body removed from its situation to shew 

 the cavity containing the Ciliary Nerves. 



FIG. 2. 



The Anatomy of the internal Ciliary Processes, as seen in the Eye of the com- 

 mon Ox. 



a The Iris cut up and reflected ; the cornea has been removed. 



b The Lens in situ, inclosed in its capsule. 



c The internal Ciliary Processes seen anteriorly. 



d The same seen posteriorly ; the choroid has been removed. These different 

 portions of the internal ciliary processes are quite continuous, but are firmly 

 attached to the external ciliary processes immediately beneath the point f. 

 At c the external ciliary processes have been entirely removed, and an open- 

 ing made into the Canal of Petit. 



