IN THE EYE OF THE CHAMELEON. 
105 
is caused hy a remarkable thinness of the retina at this 
point. The retina around the foramen has adhering to it 
a quantity of black granulated matter, which it probably 
receives from the choroid. 
Exactly at the point corresponding to the foramen^ the 
choroid is somewhat elevated internally, whilst it transmits 
externally a dark-coloured membranous canal or tube to 
the sclerotic. This is the only point at which I have found 
the choroid adhering to the^ sclerotic in these animals. 
Nothing novel is shewn by examining the foramen cen- 
trale under the microscope, but the structure is naturally 
rendered more distinct. We perceive that the foramen is 
not quite circular, but somewhat irregular in its margin, 
and that the actual aperture is smaller than might be other- 
wise supposed. This diminution in the real size of the 
aperture is owing to a thin semitransparent layer, proceed- 
ing from the more solid and opaque retina towards the 
centre of the aperture. I hope soon to be able to submit 
to the Society some further researches on this subject. 
I ought perhaps to have added, that most of the dissec- 
tions detailed in this and in my former paper announcing 
the discovery, were performed in the presence of numerous 
friends ; most of the preparations are in my possession, and 
will be deposited in the Museum ; but I have reserved a 
few specimens, lest any of the members of the Society, ac- 
customed to minute research, should desire to examine the 
structure for themselves. 
Explanation of Plate IV. 
Fig. 1. Represents the head of a variety of the Lacerta 
supe7Xiliosa. The eye was dissected in situ ; the 
whole dissection consists in snipping off with a pair of 
