IS.'fi • MICROSCOPICAL JOURNAL. 413 



Does tlie eye appHHr to be tnohile? Locate the parts that 

 show, viz: the pupil, tlie circiilnr central opening; the tra* 

 encircling the puitii, silvery in color; the transparent 

 cornea, covciin^ ihe })U]»il and iris; I'eyoud the cornea 

 enclosing the sides and back the white tough outer 

 sclerotic coat of the eye. Seize the eye firmly in the for- 

 ceps l>y the sclerotic coat and pnll it out of the orbit, a» 

 you do this notice and cutaway the hnrn\.» oi muscle which. 

 attach it to the orbit, and at the back of the orbit notice 

 and cut the white cord optic 7ierve. which runs through; 

 the sclerotic c^at into the eye. Place the eye in clear 

 water and with a sharp knife or scissors split it in two 

 halves in a plane passing through the optic nerve, this 

 will disclose: the anterior chairiber of the eye, betweea 

 the cornea and the iris; the larger posterior chamber, be- 

 hind the iris; and inside the posterior chamber the spher- 

 ical lens. On the back of the eye inside the sclerotic- 

 coat, the black choroid coat, ihe vascular layer can be seea 

 and inside this (in well preserved specimens) the white 

 retina. Repeat this dissection on the other eye; in re- 

 moving it from the orbit study the muscles that fasten 

 the eye- ball to the orbit and note that they are made of 

 fibers which by pulling roll the eye in its orbit, they are 

 not here sub-divided (as in the skate) into the six muscle* 

 of the eye of the higher vertebrates. Draw a diagram- 

 matic longitudinal section of the eye in place in the orbit 

 and show all these points. 



[5. The Ear, — is present in teleosts, but there is no 

 external indication of its presence; it is located in a car- 

 tilage and bone capsule, on the side of the brain case 

 and at the hinder level of the head; it has three senn-cir- 

 cular canals like the higher vertebrates, and there are 

 large calcareous structures otolith, in an additional cham- 

 ber, the vestibule; branches from the 8th cranial nerve 

 (auditory) go to the ear on each side from the medulla 

 oblongata.] 



