204 THE EYES OF THE BLIND VERTEBRATES OF NORTH AMERICA. 



Fig. 36. Anterior face of a transverse section of the left eye of a larva 5 mm. long. The sections run obliquely in 

 such a way that the right eye is cut first, the series beginning in front. The divergence from the spheri- 

 cal outline is due to the pressure of the brain on the proximal face and the epidermis on the distal face. 



Fig. 37. Anterior face of a transverse section of the left eye of a larva 6 mm. long. There is no lens in connection 

 with this retina. 



Fig. 38. Parasagittal section of an eye of a larva 6 mm. long, showing ventrally the choroid fissure represented by 

 the space between the pigmented layers and the vitreous cavity represented by the shallow depression 

 on the ventral face. The retina is differentiated into ganglionic, inner reticular, and nuclear layers. 



Fig. 39. Anterior face of a transverse section through the right eye of a larva 7.5 mm. long. 



Fig. 40. Horizontal section through the middle of the eye of a larva 7 mm. long, showing the choroid groove. 



Fig. 41. A horizontal section 10 micra dorsad to that given in Fig. 40, and showing the iris and vitreous cavity. 



Fig. 42. Outline of the lens of the same eye as that shown in Figs. 40 and 41, but at a level 30 micra dorsad 

 of Fig. 41. 



Fig. 43. Region between the eye and the epidermis of a larva 7.5 mm. long, showing the degenerating lens. 



Fig. 44. Lens of a larva about 7 mm. long. 



Fig. 45. Vertical section near the centre of the right eye of a fish 9.5 mm. long. 



Fig. 46. Anterior face of a transverse section through the eye of a fish 9.5 mm. long. 



Fig. 47. Horizontal section through the left eye of a fish 9.5 mm. long. 



Fig. 48. Scleral cartilage of the right eye of the same fish as that from which Fig. 47 was taken. 



Fig. 49. Scleral cartilage of the left eye of another fish of the same size. 



Fig. 50. Exit of the optic nerve from the eye of Chologaster papilliferus showing the ganglionoid cells (z.) at the 

 entrance of the optic nerve. 



