THE ou<; I 





the dermal scutrs acquire- a special condition and form, and, above all, 

 aretran-paivnt. 



In regard to the particular form of t h.- ..r^.-m. t here are essentially 

 three types to be disiiiiL'uMi. d. 



In many llrptil,^. ,.,/., in I'latyd.ict vliK. tin- pineal -land ha- tin* 



same structure a.s in Sharks: a small peripheral vesicle, win'.- 



c/,6 p U 



A -4 



Fig. 244. Diagrammatic longitudinal section through the brain of Chameleo vulgaris with the- 

 pineal organ, which is separated into three portions, a vesicular, a cord-like, and a tube-lik 

 portion, afUT BAI mvix SI-KN. 



! bone with the foramen parietale ; ;. :" tli- integument; *, oon.l-lik 



niidi'.le portion of the epiph ysis ; bl, its vesicular terminal portior ; r, transparent region 

 of the integument; grh, cerebrum; ih, optic thalamus; v', thml Nentiulo, which is 

 continued upwards into the tube-like initial portion (A) of the t>i>ii>hyua. 



enclosed in the parietal foramen, is lined with ciliated cylindrical 

 cells, and is connected with the roof of the between-brain by means 

 of a long, hollow stalk. 



In other Reptiles, as in the Chameleon, the organ is ditl' : 

 into three portions (fig. 244) : first into a small closed vesicle (bl), 

 which lies under a transparent scale (x) in the foramen pari 

 and is lined with ciliated epithelium ; secondly into a solid cord 



28 



