380 PHYSIOLOGICAL SERIES. 



There is a clearly defined rhinal fissure from the bend of 

 which tiie Sylvian fissure ascends obliquely. The Sylviau 

 fissure is concurrent with the intraparietal, as in the lirain 

 of Chrytotkrix. This " suprasylvio-lateral w fusion is of 

 interest as a further extension of that process which results 

 in the formation of the Sylvian fissure of the Primates by 

 a blending of the suprasylvian and the inconstant supra- 

 rhinal kinks (pseudosylvian fissure). 



There is an extensive parallel sulcus behind the Sylvio- 

 intraparieta] complex, and fragments representing an inferior 

 temporal sulcus behind and below the parallel. 



In front of the Sylvian fissure we find the following 

 sulci in order from below upward : the almost sagittally 

 directed orbital close to the olfactory peduncle, a triradiate 

 sulcus rectus, and then another sagittal sulcus (of very 

 doubtful homology) nearer the mesial plane (fig. 221, a] . It 

 often happens, however, in the Apes that when the Sylvian 

 and intraparietal elements fuse, an accessory infra-parietal 

 sulcus makes its appearance in a position analogous to that 

 occupied by this sulcus. 



On the left hemisphere the posterior part of the intra- 

 parietal sulcus is separated from the rest. The parallel 

 sulcus is not bifurcated as it is on the right side. 



On the mesial surface the two limbs of the calcarine 

 are so large as to simulate the parieto-occipital and post- 

 calcarine (posterior calcarine) sulci of the Anthropoidca. 

 There is a short intercalary sulcus and also a small and 

 faintly marked rostral sulcus. 



There is a deep notch on the ventro- caudal margin of the 

 hemisphere (not only in this brain but in most Lenmrid 

 brains), for the true interpretation of which we must 

 examine a series of Ape-brains. It will then be found to 

 represent a compensatory sulcus, the place of which is 

 taken in a higher phase of development by the collateral 

 and inferior occipital sulci, to which in the highest Apes 

 we may add the occipito-temporal. It cannot, however, 

 be strictly said to represent any one of these three sulci 

 exclusively. 0. C. 1337 B c. 



Th. Ziehen, Arch. f. Psych., Bd. xxviii. 18%, p. 905. 



