384 REPTILES xiv. 9 



functions from lower levels of the nervous system to the cerebral 

 hemispheres, a process that has been carried much farther in mam- 

 mals. In most respects, however, the brains of modern reptiles are 

 more like those of birds than of mammals. 



The behaviour of reptiles, despite the elaborate courtship of some 

 forms, remains of a relatively stereotyped character. The eyes are 

 usually the main exteroceptive sense-organs and are usually provided 



co it dors. 



cort. hipp. 

 sutc Llm 



cert Cat 



.ircfnstr 



■palaeostr 



Fig. 217. Transverse section through forebrain of Lacerta. 



archistr. archistriatum (upper part of corpus striatum); cort. dors, dorsal cortex; cort. hipp. 

 medial (hippocampal) cortex; cort.lat. lateral (pyriform) cortex; palaeostr. paleostriatum 

 (basal part of corpus striatum); sept, septum; sidclim. sulcus limitans. (After de Lange 



and Kappers.) 



with movable eyelids, including a third eyelid or nictitating membrane. 

 The lacrymal and Harderian glands provide secretions that keep the 

 surface of the cornea moist. The eye is supported in most reptiles by 

 a scleral cartilage and a ring of bony scleral plates. Accommodation is 

 produced by the striated ciliary muscles, so arranged that they cause 

 the ciliary process to squeeze the lens, making its anterior surface more 

 rounded (Fig. 218). In many reptiles the retina possesses both rods 

 and cones, the latter predominating in diurnal types. 



The pineal complex is often well developed, and in Sphenodon and 

 many lizards a 'pineal' or parietal eye is present with lens-like and 

 retina-like components. In such forms there is a pineal foramen in 

 the parietal bone near the fronto-parietal suture. Similar foramina 

 are found in many fossil reptiles, especially the more primitive types. 

 The function of the reptilian pineal is still rather obscure, but there 

 is evidence that in lizards it registers solar radiations, and, perhaps 

 by the secretion of hormones, influences the animal's thermoregula- 





