Clark, Comparative Anatomy of the Instda. 75 



ing the presence of a claustrum indicating the presence of an 

 insula at first seemed plausible but later reflection has caused 

 the idea to be abandoned (see discussion under Carnivora). 



THE INSULA IN THE PRIMATES OTHER THAN MAN. 



The anthropoid apes, which in structure are so closely 

 allied to man, possess a well developed insula. 



Leuret and Gratiolet seem to have been the first to recog- 

 nize this area. They say (31, II, 112): " Le lobe central parait 

 particulier a I'homme et aux singes, peut-etre voit-on quelque 

 chose d'analogue dans les makis, mais on ne voit rien de sem- 

 blable chez les autres mammiferes. " 



In 1891 Cunningham (13, 287) said: "One of the most re- 

 markable characters in the cerebrum of the orang and the chim- 

 panzee is the total absence of the frontal and orbital opercula. 

 The temporal and fronto-parietal opercula are alone present." 

 There is some diversity of opinion as to the entire " absence " 

 of the suboperculum in these brains and Cunningham also admits 

 the presence of a fissure which forms the cephalic boundary of 

 the operculum but he does not believe it homologous with the 

 presylvian fissure and hence does not recognize a suboperculum. 

 Cunningham (13, 287) also says: •' It is curious that while the 

 anthropoid should be so absolutely destitute of a frontal and 

 an orbital operculum, there are many of the lower apes (e. g. 

 baboons, macaques, etc.) which show a faint trace of the orbital 

 operculum." 



In 1880 Parker, (4(j) stated that the insula of the 

 chimpanzee " is well developed and is marked by several con- 

 spicuous radiating convolutions (gyri breves. Gall) and lies en- 

 tirely concealed beneath a well-developed operculum." 



In 1877 Major (34,46) said the insula was relatively as 

 well as absolutely smaller in the chimpanzee, etc., than in 

 man. 



Hartmann (26, 195) in 1886 wrote that "In the gorilla, 

 chimpanzee, and orang, the island of Reil is generally — at least, 

 according to my experience — overlapped by the operculum, 

 although there are instances in which this is not the case." 



