PINEAL EYE IN LACERTILIA. 185 



spherical masses of deep brown pigment {pig^), connected in 

 some cAses with the pigment enclosing the rods ; beyond this, 

 again, a certain amount of pigment in minute granules is 

 scattered irregularly amongst the external spherical elements, 

 and completely external to the optic vesicle posteriorly is 

 massed around the entrance of the nerve a great amount of 

 eoL pigment deposited in branchial cells [pig.^). 



Nerve. — The pineal stalk is well marked in Varanus 

 giganteus and differs moreover from anything met with 

 amongst other forms (even other genera of Varanus).^ 

 Instead of being single there are three distinct nervous strands 

 entering the vesicle posteriorly ; two of these are more promi- 

 nent than the third, which appears to be in connection with 

 the anterior of the former ; the single posteriorly placed nerve 

 entering very nearly but not quite in the line of the optic 

 axis. The larger and smaller anterior strands join together, 

 and then, after a marked curve, shared in by the posterior 

 one, they join the latter and run back as the solid pineal stalk 

 to the proximal part of the epiphysis. 



At first it seemed possible that the appearance described 

 might be due to the cutting in longitudinal section of the walls 

 of a hollow stalk distorted somewhat by reagents, but an 

 examination of a continuous series soon showed that this was 

 not the case, and that the pineal stalk, single proxi- 

 mally, broke up distally into two, and finally into 

 three separate nerves entering the optic vesicle. 



The most noticeable features in the eye of Varanus are : 



(1) The great development of pigment in all parts, and 

 more especially in the lens. 



(2) The curious nature of the retina, which has really the 

 form of a cellular network ; the cells being in connection with 

 one another by branched processes, the nuclei being scattered 

 somewhat irregularly and giving rise, together with the proto- 

 plasm around them, to the spherical elements of the retina. 



1 The only other lizard as yet examined, in which anything comparable to 

 this is found, is Lacerta ocellata, tobe described later on. 



