430 PHYSIOLOGICAL SERIES. 



occipito-temporal sulcus is very long and deep, its extension 

 having taken place at the expense of the collateral suleus. 

 On the left hemisphere the little inferior occipital sulcus 

 is linked to the occipi to-temporal sulcus, just as occurs 

 in the corresponding hemisphere of the Guinea Baboon 

 (D. 631). 



The calcarine sulcus has two long diverging caudal 

 limbs, as well as several accessory sulci surrounding it. 



The superior frontal sulcus is exceptionally well- 

 developed. 



But by far the most interesting and important feature of 

 this brain is the condition of the anterior insular region. 

 On the right side, this region does not markedly differ 

 from that already described in the case of the Hoolock 

 Gibbon (D. 644). But in the left hemisphere the fronto- 

 orbital sulcus is very deep (as it also is on the right side), 

 and the superior limiting sulcus is prolonged forward so as 



DORSRFLOC. FLOC. 



almost to reach the fronto-orbiud (in fact, on casual exam- 

 ination it appears to do so) : moreover, the dorsal lip of the 

 superior limiting sulcns has become opercular, so that the 

 anterior insular region is not onlv almost completely 

 surroundeil by sulci, but is also depressed below the level 

 of the surrounding areas. Thus a condition is produced 

 \vhieh finds a elo-e parallel in the developing human brain. 



(Compare Cunningham's observations on the analogoua 



phenomena in the Chimpanzee's brain, Journ. Anat. & 

 I'lix-. vol. xxxii. 18 ( J8, pp. 11 et M/.) 



The trape/.ium, although covered by the pons to a much 

 greater extent than in Papio, is still distinct laterally. 



The floccular lobe i sembles that of the Cercopithecidfle, 

 and is relatively much larger than it is in the Anthropoid 



