98 THE LOWER PRIMATES 



portion of the cerebellum. A well-defined llocculus and parallocculus are 

 attached along the region of confluence with the axis. 



The occipital surface also occupies a vertical position and as yet has not 



FIG. 47. RIGHT LATERAL SURFACE OF BRAIN, TARSIUS SPECTRUM. 



[Actual Length, 21 nim.l 



been tipped backward, as is the case in higher primates. This fact accounts 

 for the exposed position of the uvula and nodule which have not yet under- 

 gone that introversion which produces their ultimate intraventricular relation 

 characteristic of most of the anthropoids. 



The fissures of the cerebellum have an almost diagrammatic clearness in 

 producing the three major subdivisions of the cerebellum. The lissura prima 

 appears upon the tentorial surface and extends outward from the vermis upon 

 the lateral lobe without sulcal interruption. This is likewise true of several 

 other fissures of this surface. The fissura secunda appears in relation with 

 the occipital surface but, as in other mammals, it does not extend out upon 

 the lateral expansion of the cerebellum, being interrupted by the presence 

 of a definite paramedian sulcus. All things considered, the cerebellum of 

 tarsius is the most primitive of all primates, and yet it foreshadows in so 

 many notable details the future development of this organ in apes and man 

 that it must be regarded as inherently anthropoid. 



