ANATOMICAL STRUCTURE OF ANTHROPOID APES. 197 



tiolet to be absent in anthropoids ; but Eolleston, 

 Bastian, and myself have all found it well deve- 

 loped * (Fig. 56, orang, and Fig. 58, gorilla). 



Bischoff asserts that the third frontal convolution 

 (Broca's convolution) is very slightly developed in 

 the chimpanzee, orang, and gibbon. "Its great 

 development in men," Gewahrsmann writes, "con- 

 stitutes one of the most marked distinctions between 

 the brains of apes and of men." f In most of the 

 other species of apes this convolution is altogether 

 absent, but Pausch is justified in the assertion that 

 it is fully developed in anthropoids. I cannot wholly 

 agree with Pansch in his analysis ; but I must 

 accept his statement oq this point (see the orang. 

 Fig. 59). Gratiolet remai-ks that the so-called 

 annectant gyri {plis de passage) which serve 

 as a covering or operculum for the posterior lobes 

 in apes, are only superficially apparent in man. In 

 the chimpanzee the upper of those convolutions 

 is absent, while it is large in the orang, and likewise 

 large and undulated in man. In the orang the 

 second annectant gyrus is covered, but this covering 

 is absent in man.J 



In considering the inner structure of the brain 

 of these animals, we are first struck by the shortness 

 of the corpus callosum. The soft and thick anterior 

 commissure of the third cerebral ventricle and the 

 thin posterior commissure have also been justly 



* Natural History Review, p. 201 : 1861. 



+ Sitzung der Mathematisch-physikalischen Klasse der konigl. 

 hairischen Akademie der Wissenscliajten, p. 100 : Feb. 4, 1871. 



X Gratiolet, Mem. sit-r les plis cdr^braux de Vhomme et des 

 primates. 



