NERVOUS f SYSTEM. VERTEBRATA. 245 



the size of the body upon the proportions and form of the 

 bruin. In animals of the same Order (and more especially 

 of the same genus) the brain is much larger in the bigger 

 species ; but the increase in size is not proportionate to that 

 of the bodily dimensions, the smaller animal having a brain 

 relatively much larger than that of the bigger animal. 

 This is due to the fact that in mammals of the same genus 

 (i. e. in animals in which the other determining factors of 

 the size of the brain may be neglected as being common to 

 tbe two forms) the size of the pallium varies directly with 

 that of the areas of the sensory surfaces, and these are 

 relatively greater in a small than in a large animal. (See 

 Dubois, Bull. d'Anthropol. de Paris, 1897, p. 337.) 



As a result of the larger size of the neopallium, the sulci 

 become deeper and longer and secondary sulci make their 

 appearance. 



FIR. 117. 



PYR.L. 



* The " Sylvian fissure " (so-called) is much deeper and 

 cuts into the neopallium much more obliquely than is the 

 case in the Cat's brain. Thus a large anterior lip is de- 

 veloped so as to overlap the depressed posterior lip, which is 

 exposed by raising, or better by cutting away (fig. 117), 

 the anterior lip. The submerged posterior lip is then seen 

 to be indented by two sulci (fig. 117, A and B). In this 

 specimen (D. 294) the condition thus described as typical 

 of the Lion's brain does not obtain, and a condition essen- 

 tially identical with that of the Jaguar's brain (vide infra 

 D. 297) is present. 



* [The following remarks are based upon the careful examination of the 

 brains of three Lions, which were removed from the skulls by the writer 

 shortly after the death of the animals : thus a more accurate account is 

 given than would be possible from the study of old Museum specimens.] 



