A Study of Cerebral Anthropology 33 



attempt to harmonize the various opinions as to which of its ele- 

 ments are represented in apes, although the question is of great 

 interest. Cunningham (1890&) says, "I think the lower in the 

 scale we descend the less the relative morphological importance of 

 the fissure of Rolando as compared with the interparietal sulcus." 

 We must consider under this name a number of elements which 

 vary in the completeness of their development and their relation 

 to each other. They are the sulcus retrocentralis inferior, the 

 sulcus retrocentralis superior (between these the sulcus retro- 

 centralis intcrmcdius) , the sulcus inter parietalis proprius, and the 

 sulcus occipitalis transversus. Cunningham considers that the 

 elements sulcus retrocentralis, ramus horizontalis (s. inter- 

 parietalis proprius) and ramus occipitalis (s. occipitahs trans- 

 versus) represent the fissure as it is seen in apes. Eberstaller 

 introduces another element, the sulcus subcentralis posterior 

 (Marchand), which is present in most apes. Retzius does not 

 agree with this idea, but considers this sulcus as belonging to the 

 group of the operculum. Retzius (1896) introduces the element 

 sulcus retrocentralis intermedins, and reports it present in 4 per 

 cent, of his series of brains. 



The greatest amount of study of variations of elements has 

 been placed on the several combinations which they present. 

 Their arrangement can be most graphically represented by the 

 diagrams used by Retzius. 



Type I. Type II. Type III. Type IV. Type V. Type VI. 



Observer. I. 



Retzius 55 



Cunningham 69 



Cunningham (Negro) 2)7 



Duckworth (Australian) ... — 



Duckworth (Embryo) 5.9 



Sernoff 44 



For additional figures see table, page 28 



2,77 



