THE PINEAL SYSTEM OF LACERTIDA 28l 



In some cases the walls of the epiphysis may be folded ; thus Studnicka 

 describes in a specimen of L. agilis a series of lateral buds, right and left, 

 on each side of an elongated sac-like epiphysis ; and Leydig found a 

 similar condition in L. ocellata. In this specimen the epithelial cells at the 

 distal end of the epiphysis were pigmented, as in a case of Anguis fragilis 

 also described by Leydig. 



Scincidae. 



The skink family comprises a number of different species, mostly 

 found in sandy deserts and often showing retrogressive features, such 

 as the union of the premaxillas and diminution in the size and number 

 of the limbs, the fore-limbs or both fore and hind-limbs being absent 

 in some species. In Chalets flavescens, a long, worm-like animal, both 

 pairs of limbs are present, but are less than 2 mm. in length. One interest- 

 ing adaptation to a dust-blown sandy environment is the existence in 

 certain skinks of a transparent window in the lower eyelid of each lateral 

 eye, which allows the eye to be used when closed, while at the same time it 

 serves as a protective covering for the eye. 



Cyclodus gigas. 



A description of the pineal system of this animal was given by Spencer 

 in 1886. A corneal scale, parietal fleck, and parietal foramen were all 

 present. The pineal organ took origin from the roof of the diencephalon 

 in the usual situation, and coursing forward with an arch-like bend, ended 

 in a vesicular expansion above the anterior part of the hemispheres and 

 in the region of the parietal foramen, which it partly filled. Spencer 

 regarded this expansion as a parietal eye which had remained in an 

 undeveloped and rudimentary condition. Studnicka, however, states 

 that there can be no doubt that the structure described by Spencer as a 

 parietal eye was in reality the well-developed end vesicle of a completely 

 formed pineal organ, and that the parietal organ had not been developed. 

 Both the upper and the lower wall of the end vesicle was composed of long, 

 cylindrical cells from which cilium-like processes projected into the lumen 

 of the vesicle. 



Gongylus ocellatus. 



Legge (1897) described the pineal diverticulum of an embryo 10 mm. 

 long, which was divided into a distal part, which he considered to be 

 the rudiment of the parietal eye, and a proximal part, the epiphysis. 

 The distal segment, namely, the parietal eye (or possibly the end vesicle 

 of the epiphysis), had disappeared in those specimens which had passed 

 the embryonal period, and there remained only the true epiphysis which 



