PINEAL EYE IN LACBRTILIA. 187 



brain membraues wheu the surface of the skull was removed 

 from above the braiu. 



The connective tissue lying external to the eye is quite 

 transparent, and being placed as it is immediately beneath the 

 skin, the entrance of light is thus made possible ; in fact, it is 

 impossible to prevent the light from entering, not only in this 

 but in the case of the pineal eyes of all other Lacertilia, when 

 they are placed so near to the skin. 



In section, the eye of a somewhat larger V. bengalensis 

 shows the following structure differing much from that of 

 V. giganteus, a difference the more noticeable since it exists 

 between members of the same genus. 



Fig. 41 represents a longitudinal section along the median 

 line of the head passing through the parietal foramen ; the 

 results are represented somewhat diagrammatically. The eye 

 lies within the foramen tightly enclosed again within connec- 

 tive tissue, no special capsule being present. A very notice- 

 able feature is the entire absence of pigment above the eye, 

 though this is present in abundance in the skin elsewhere 

 {Ct, pig.) in the connective tissue of the cutis vera. The eye 

 itself is depressed dorso-ventrally, so that but comparatively 

 little space remains within the vesicle ; the latter lies directly 

 above the anterior extremity of the proximal part of the 

 epiphysis, which runs right up into the foramen from the dorsal 

 wall of the thalamencephalon lying some distance posteriorly. 



Fig. 17 gives a more detailed representation of the foramen 

 with its contents. Beneath the cuticle (cu.) the epidermis is 

 seen {ep.), then the rete mucosum, the nucleated cells of which 

 are in this part somewhat longer than those elsewhere ; beneath 

 this lies the connective tissue of the cutis vera (Ci). On either 

 side of the foramen are numerous pigment cells (Ct, pig.), and the 

 fibres as before may be divided into two series — (1) a set running 

 at right angles to the long axis of the head, and (2) others form- 

 ing a roof for the foramen, and connected with those lying within 

 the latter, which form a close investment for the eye (Ct^). 



Within the foramen also is a much branched blood-vessel which 

 enters along with the epiphysial stalk; a small branch passes for- 



VOL. XXVII, PART 2. NEW SEK. O 



