Mr. W. B. Spencer. 



[June 10, 



and the presence of the branched pigment cells renders the examina- 

 tion of its structure very difficult. 



A well developed cellular lens is present, formed from the anterior 

 part of the vesicle apparently. The retinal elements are imbedded 

 in pigment, and, save the rods, are difficult to detect, though by care- 

 ful examination two rows of round nucleated cells may be detected. 

 The pigment obscures the nerve, which is nothing like so clearly 

 marked as in Hatteria, due largely to the dura mater encasing the 

 eye so closely that no capsule is formed. 



The nerve enters posteriorly, and a slight differentiation of the rods 

 at two points may be noticed, the nerve appearing to divide into two 

 just before entering the eye ; it passes down, lying in the dura mater 

 to join the proximal part of the epiphysis, which is itself deeply pig- 

 mented. 



The blood-vessel accompanying the nerve is well developed. 



(c.) Iguana. — The structure agrees in the main with that of Hatteria, 

 though, owing to the eye being not so well preserved as in the latter, 

 the elements cannot be so clearly differentiated. The lens is cellular, 

 and somewhat similarly shaped to that of Hatteria ; the rods are as 

 usual deeply pigmented, and external to them may be detected (1) a 

 row of round nucleated cells ; (2) a well-marked molecular layer, in 

 which the nucleated cells are often embedded ; and (3) an outermost 

 layer of cone-shaped bodies, similar to those of Hatteria. 



The rods in the optic axis are again lengthened out and prominent, 

 running down into the nerve. 



The eye lies in a capsule of connective tissue within the foramen, 

 and into the same space passes also a hollow process from the 

 epiphysis, into which the nerve enters. 



In another Iguana examined the process appears not to be hollow, 

 and the eye, instead of lying in a capsule, is closely invested by con- 

 nective tissue. 



In both cases the vesicle is filled with a coagulation, indicating the 

 presence of a fluid material in life. 



(d.) Anolius (sp. ?). — The eye lies close beneath the skin, and almost 

 entirely fills up the parietal foramen, the remainder being occupied 

 by vacuolated tissue, in which large nucleated cells are present at 

 intervals, together with branching pigment cells. 



The eye is elongated in the direction of the optic axis, and provided 

 with a nerve running back through the vacuolate tissue and entering 

 the proximal part of the epiphysis. 



Pigment is largely developed, ensheathing all the elements of the 

 retina ; the rods may be traced into rounded elements ; these again 

 externally into cone-shaped elements. The rods in the optic axis are 

 again modified :<,nd prominent, and their ends facing into the vesicle 

 appear striated. 



