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Nachdruck verboten. 



A Note on the Forebrain of Chimaera^). 



By J. B. Johnston. 

 With 27 Figures. 

 To make clear the references in the following paragraphs to the 

 forebrain of selachians it is necessary to explain the subdivisions re- 

 cognized by the writer. These have been defined in a preliminary 

 paper recently published in the Anatomical Record and will be more 

 fully treated later. Fig. 1 will serve to show sufficiently well for the 



Fig. 1. Sketch of the right half of the forebrain of Scyllium viewed from the 

 medial surface, som. area., the somatic correlation center from which the general cor- 

 tex is developed ; v. tr., velum transversum, which marks the boundary between di- 

 encephalon and telencephalon; n. term., nervus terminalis of LOCY. Other abbreviations 

 will be readily understood. 



present purpose the relative positions of the primordium hippocampi 

 and the primordial somatic cortex with reference to the medial ol- 

 factory nucleus. The lateral olfactory nucleus lies about the base of 

 the olfactory peduncle on the lateral aspect. The primordium hippo- 

 campi includes the massive roof above and behind the external neur- 

 oporic recess. The somatic cortical area occupies the greater part 

 of the lateral wall of the unpaired ventricle and extends forward to 

 meet the lateral olfactory nucleus. 



Several recent authors have made references to the brain of 

 Chimaera in connection with the forebrain problem. Edinger in the 



1) Neurological Studies from the Institute of Anatomy, University 

 of Minnesota, No. 11. 



