PEOSENCEPHALON OF MAMMALS. 



115 



primary convolutions may be traced. The Proboscidia^g. 108, and 

 Cetacea, fig. 85, show excess of convolution of the cerebral surface. 

 Erasistratus l affirmed the convolutions to be most numerous in 

 the brain of Man, and associated them with his superior intelli- 

 gence. Willis 2 pointed out that the convolutions, though present, 

 were fewer in brutes than in Man ; that the Ape had more of 

 them than the Fox or Dog, c. ; that paucity was associated 

 with regularity and symmetry of folding and with more definite 

 and limited instincts, while the want of symmetry of the more 

 richly convoluted brains was associated with greater diversity and 



85 



Brain of the Dolphin, Delphinus DetyJiis. xxr.v 



freedom of mental operations. By these remarks Willis initiated 

 the comparative anatomy and physiology of this part of the brain. 

 Vicq d'Azyr 3 noted the symmetry of the convolutions in the 



brain of the Monkev, and contrasted it with the want of such 



/ - 



symmetry in Man. Malacarne 4 first defined a particular convo- 

 lution, that, viz., which overlies and follows the contour of the 

 corpus callosum. Tiedemann does not enter upon the comparison 

 of the convolutions ; but he first showed the order and periods of 

 their successive appearance in the human brain. 5 Serres 6 stated 

 them to be too inconstant to characterise species or families of 

 Mammalia. I early made observations to test this question, and 



in 1833 I communicated the results in regard to the convolutions 



~ 



of the cerebrum in the Fellclce, 7 distinguishing the ' folds ' by 

 letters, and the ( fissures ' bv figures ; 8 and finding that their 



v O O 



1 XLIV. ~ XXI". 3 XLV. 4 XLVI". 5 XXX". 6 XXXII". 7 XT.VII". 



8 This mode of notation has been reversed by a subsequent author, but no advan- 

 tage from the innovation is pointed out, or seems to be gained thereby. 



I 2 



