4 ACCOUNT OF THE FORAMEN CENTRAi^E 
having most kindly and liberally furnished me with the 
necessary specimens from the Museum, and, at the same 
time, pointed out the works of the comparative anatomists 
of Germany, with whose labours he is intimately acquainted, 
I deemed it a favourable opportunity for completing my 
inquiry into the organ of vision, and of adding to those 
observations which I had the honour lately to submit to 
the Royal Society of Edinburgh. It is not my intention 
here to enter into any details relative to the eye of Reptiles 
generally, but simply to describe the transparent point, or 
foramen centrale^ and fold of the retina, which I have 
found to be comparatively much more developed in these 
animals than in man himself. 
The animals in which these appearances were discovered 
by me were all of the Lizard tribe *, and the first in which 
L remarked the presence of the transparent point, was the 
Laceria superciliosa of naturalists. The notes taken during 
the dissection are as follow. 
Imo, The eye-ball comparatively large, resembling in 
external form that of the bird; the sclerotic horny and 
strong anteriorly, of a bluish colour, soft and elastic pos- 
teriorly. The retina very thick, somewhat firm and opaque. 
Where the optic nerve enters the interior of the eye-ball, 
there is a distinct marsupium, or black circular body, pro- 
ceeding forwards apparently through the centre of the vi- 
treous humour : this membrane, no doubt, incloses the 
bloodvessels distributed to the lens, hyaloid membrane, 
&c. Anteriorly, somewhat superiorly and towards the 
mesial line or plane, we perceive, on looking on the surface 
of the retina which regards the vitreous humour^ a com- 
paratively large transparent, nearly circular spot, through 
* I ought to remark, that the most of these specimens had been pre- 
served for a great length cf tmie hi sphitp. 
