813 



aoconiit of the order of mjeliiiisation of the fibre trncts in the cliick, 

 (ieiiioiistiates the presence of a band of fibres on the ventricular 

 aspect of liie dorso-occipital part of tiie corpus .striatum. Some of 

 these fibres in the kiwi enter into the formation of tiie inter-epistriatic 

 commissure. It is probable that these commissural fibres are com- 

 parable to the jibrae mnrginale.s found on the ventricular aspect of 

 the striatum of Varanus and crossing to the opposite side in the 

 comniissurn anterior (cf. de Langk, op. cit. Fg. 19, 20). The further 

 description of the inter-epistriatic commissure will be deferred until 

 the discussion of the subdivisions of the corpus striatum is undertaken. 



/;. The Corpus Striatum. 



Notwitiistanding tlie unusual external features of the brain of 

 Aptenjx to which reference has already been made the outstanding 

 features of the sections are defiiiitel3- avian. In 1891 Professor T. J. 

 Pakker observed that his investigations of the development of the 

 brain of the kiwi though very imperfect owing to lack of material 

 "prove conclusively what might have been inferred fiom adult ana- 

 tomy, that the brain of Aptenjx is simply a typical avian encephalon 

 with reduced optic lobes." (p. 107). 



As is usual in Aves, the forebrain of the kiwi consists, for its 

 greater part, of the corpus striatum. This body appears on each 

 side as a great ventricular bulging. Frontally it forms the frontal 

 pole of the hemisphere. Caudally its posterior extremity projects 

 freely into the ventricle in close proximity to the hinder pole of the 

 hemisphere. In the more frontal sections (Fig. V — VIII) the lateral 

 ventricles form two vertical slits separated from one another by 

 the two thin laminae constituting the septum and the corpora striata 

 form the vertical lateral boundaries of the ventricles in this region. 



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