414 TROF. G. ELLIOT SMITH OX THE 



uould seem to indicate that tlie "coronal" sulcus of the Viverridie, of the Ungulata, 

 and of the Lemurs oucfht properly to be regarded as prorean-coronal. For the constant 

 development of the prorean sulcus in those hrains (of such widely separated mammals 

 as the Marsupials, Edentates, and Carnivores) in whicli its union with the coronal sulcus 

 is prevented by a " mechanical " extension of the orl)ital seems to indicate that the 

 prorean siilcus possesses some definite individuality and mori)holog-ical stability. 



In the brain of Chiroinys there is a peculiar modification of this region (which shows 

 unmistakable signs of retrogressive change). In some cases there is a definite typical 

 orl)ital sulcus and, in a more dorsal position, another sulcus which is obviously the 

 anterior part of a coronal (or prorean-coronal) sulcus which has become broken into two 

 fragments, like that of Isycticehus. In other cases the two sidci (/. e. the orbital and 

 the anterior fragment of the j)rorean-coronal complex) become united. Oudemans calls 

 this sulcus simply " prorean." 1 think that Oudemans's and Ziehen's use of the term 

 " prorean," without being absolutely erroneous, fails to express the whole truth. 



There can be no difficulty in interpreting the sulci lateralis and coronalis in terms 

 -which are applicable to the Apes, because these two sulci (in the form seen in the genus 

 Lemur) are exactly reproduced in some of the smaller Cebidae, such as C'allithn\r. 

 The lateral sulcus becomes the intraparietal (or " interparietal," as the Germans call it) 

 sulcus ; and the coronal sulcus is identical with that variously termed "fruiitalis 

 j))'iitcq)al/s," '• rectus^' " rostmlis,'" among many other designations. It includes the 

 representatives of the two sulci called respectively "rectus" and " arciiahis" in the 

 Apes. The latter certainly x-epresents the inferior precentral sulcus of the human brain ; 

 whereas the homology of the former is the subject of great divergence of opinion. 

 Herve, El)erstaller, Waldeyer, Giacomiui, and Dubois * consider that the sulcus rectus 

 becomes the sulcus frontalis medius of Eberstaller in the human brain ; whereas 

 Cunningham and Marchand incline to the old view of Gratiolet, that it represents the 

 sulcus frontalis inferior. As I have shown in the above notes that the fronto-orbital 

 sulcus (whicli Waldeyer, Giacomiui, and their school regard as the homologue of the 

 inferior frontal sulcus) is certainly the anterior limiting sulcus of Reil, the evidence 

 seems to point to the view of Cunningham and Marchand as the true interpretation. 



Tiie jjostlateral sulcus is as variable in the Lemurs as its rejiresentative in the 

 Carnivora and other mammals is unstable. Beddard, Ziehen, and Flatau and Jacobsohn 

 tall it parieto-occipital ; Chudzinski labels it " occipital," a term which is ap^iarently 

 applied in the same way as " parieto-occipital " used by the other writers. Beddard 

 further complicates matters by applying the term " Simian" [/. e. Altenspalte] to it in 

 JS'ijcticebns (Proc. Zool. Soc. 1895, ]). lit). 



In the discussion of the mesial surface of the hemisjiherc it is shown how misleading 

 and erroneous it is to call this furrow "parieto-occipital." 



The postlateral sulcus undoubtedly becomes the sulcus occipitalis transversus of 

 Ecker in the Apes and Man. 



* '• PitheraiifhropHs erecti's" riocecdwgs of the Fourth Litcniational Congress of Zooh)g_v at Cambridge, Ic'JS 

 <^,ubli8hed ISOO), p. s3. 



