2 Mr. T. Wharton Jones on the Retina and Pigment 
arise, and immediately after their origin intercross with each 
other, those from the one side going to the opposite side of 
the eye, and contrariwise. The nervous fibrils from the fore 
end of the ganglion do not intercross, but proceed directly to 
the eye. The fibrils which thus arise from the optic ganglion 
are in very great number. They cover to a considerable ex- 
tent the posterior surface of the eyeball, and each penetrates 
singly the thin cartilaginous lamina which corresponds to a 
sclerotica. The optic fibrils having thus entered the eyeball 
expand into a layer of a light reddish-brown tinge, which I 
shall distinguish by the name of the first layer of the retina. 
What I call the second layer of the retina, is the reddish 
brown membrane, which, I have already mentioned, is the 
part usually considered as pigment. It is situated within the 
first layer; and betwixt the two there intervenes a pretty thick 
and dark layer of pigment, through apertures in which the 
nervous substance passes from the first layer of the retina to 
form the second. Examined with the microscope, the second 
layer of the retina, which, as I have said, is of a reddish 
brown colour, is observed to be composed of short fibres per- 
pendicular to its surfaces. These fibres, towards the inner 
surface, end in a delicate pulpy nervous substance, also tinged 
of a reddish brown colour, particularly on its inner surface, 
which has a corrugated or papillary appearance. 
I think it unnecessary to notice further the structure of the 
eye of the Calamary, but shall content myself with referring 
to the annexed figures (Plate I.) and their explanation. 
Since writing the above I have examined the eye of an 
Octopus, and have found the retina and pigment to possess the 
sume structure as in this Calamary. 
Explanation of the Plate. 
Figure 1. Represents the brain and two eyes of the Sepia 
Loligo. On the right side are seen the optic ganglion, and 
the fibrils which arise from it expanding themselves- on the 
back of the eye previously to their penetrating the sclerotica. 
On the left side is a horizontal section of the eye and optic 
ganglion. 
a. Cerebral ganglion. 6. Subcesophageal ganglion. c. A 
black probe introduced into the nervous collar, through which 
the cesophagus passes. d. Optic ganglion of the right side: 
e, e,e. The nervous fibrils which arise from it and enter the 
eye to form the retina. ,f Optic ganglion of the left side cut 
horizontally. g, g. Optic fibrils arising from the ganglion and 
penetrating the sclerotica at different points. A, 4, 4, h. The 
