BY G, ELLIOT SMITH. 641 



the view of Meckel that a corpus callosum is present. Haeckel 

 as recently as 1893 has made use of the following terms in 

 describing the essential features of the Marsupial and Monotreme 

 brains. Among the " Hereditiv-charactere der Monotremen" he 

 places "die primitive reptilienahnliche Bildung des Gehirns, 

 insbesondere der Mangel eines ausgebildeten Corpus Callosum," 

 and referring to the Marsupialia, "die geringe quantitative und 

 qualitative Entwickelung des Gehirns, namentlich des Corpus 

 Callosum."* Beevor, who, after an examination of the cerebrum 

 of Macropus, expressed the opinion that the superior commissure 

 was corpus callosum (Brain, 1887), elsewhere denies the presence 

 of any hippocampal commissure in certain Primates, f Apart 

 from the evidence of the presence of such a commissure which the 

 non-placental mammal affords, there is the valuable cori'oborative 

 evidence of its presence in the placental mammal by Honegger.* 

 The opinion of Owen that the corpus callosum is absent in the 

 Non-placentalia is supported by Eydoux and Laurent, f by Robert 

 Garner in Platjqjus and several Marsupials, | by Symington in the 

 clearest and best account of the subject which has yet appeared,§ 

 and Hill;|| and Edinger in the fourth revised editions of his 

 lecturesH says that all Marsupials so far examined lack a corpus 

 callosum. 



In spite of this the generally accepted opinion among recent 

 writers [of which, for instance, the works of Foster and Balfour, 

 as well as the more recent work of Minot on Embryology and the 



* " Zur Phylogenie der Australischeu Fauna," Jena. 



t " On the Course of the Fibres of the Cingulum, &c., in the Marmoset 

 Monkey," Phil. Trans. 1891. 



* " Vergleichend-anatomische UntersuchiTngen iiber den Fornix, &o.," 

 Recueil de Zoologie Suisse, Tom. v. Nos. 2 and 3. 



f " Sur r Encephale de I'Echidna compart^ a cekii de TOrnithorhynque," 

 Voyage de la " Favorite." 



+ "Anatomy of the Braiu of some small Quadrupeds," British Assocn. 

 Reports, 1858, p. 123. 



§ Loc. cil. 



il Loc. cit. 

 IT " Vorlesungen iiber den Ban der Nervosen Centralorgane," Leipsig, 1893. 



