344 



CLASS REPTILIA. 



bronchi are short and open into the lungs, which are sacs with 

 honeycombed walls. In the chameleons and some geckos 

 the posterior part of the lungs is produced into narrow 

 diverticula which lie among che viscera and foreshadow the 

 air-sacs of birds. In the snake-like forms the lungs are often of 

 unequal size. 



The brain has a small cerebellum. Almost all lizards appear 



A ' '% 



Fio. 189. — Longitudinal section through the connective tissue capsule and the parietal organ 

 of Hatteria punctata {after Spencer from Wiedersheim). g bloodvessels'; h cavity of parieital 

 organ ; k connective tissue capsule ; I lens-like thickening of the dorsal wall ; r retina-like 

 part of tlie parietal organ ; m molecular layer ; st cord connecting the organ to the pineal 

 body ; x cells in st. 



to possess a parietal organ * (Fig- 178) lying in the parietal 

 (pineal) foramen or just below it, and often in close relation 

 with the skin. This organ is a vesicle the walls of wliirh may 



* H. W. de Graaf, Bijdrage tot de hen. van d. Bouw en de Ontwickkeling 

 der Epiphyse hij Amphibien en Reptilien, Leyden 1886. Spencer, Q.J. M.S. 

 27, 1886. Beraneck, Jen. Zeitschr.,!^^", 21. L,eydig, Biol. Centralhl., 8, 

 1889, p. 707 and 10, 1890 p. 278 ; and Abh. Senckenb. Nat. Ges., 16, 1890, 

 p. 441-551. 



