136 Mr. Flower Reply to Professor Owen's [Mar. 30, 



" Meanwhile their agreement in so important a modification of the cerebral 

 organ as the absence of a corpus callosum and septum lucidum, affords ad- 

 ditional and strong grounds for regarding the Marsupialia as a distinct and 

 peculiar group of mammals." Notwithstanding this clear and definite 

 statement, which occurs again and again in some form or other throughout 

 the memoir, we are told that it is misrepresentation to quote Prof. Owen as 

 alleging "the absence in the marsupials of the corpus callosum." But Prof. 

 Owen has failed to notice that the discussion of the homological relations 

 advanced in the above cited short passage, and in similar terms in his ar- 

 ticles in the 'Cyclopaedia of Anatomy,' is by no means passed over even in 

 my abstract, as the paragraph commencing with the following words will 

 show. 



" Can this transverse commissure, of which the relation is so disturbed 

 by the disposition of the inner wall of the hemisphere, be regarded as ho- 

 mologous to the entire corpus callosum of the placental mammals ? or is it, 

 as has been suggested, to be looked upon as only representing the psalterial 

 fibres or transverse commissure of the hippocampi?" (Proc. Roy. Soc. 

 vol. xiv. p. 72.) If, after the words " as has been suggested," I had added 

 "by Prof. Owen," there would, I believe, have been nothing wanting to 

 complete as fair and full an exposition of that author's views as was com- 

 patible with the limits of an abstract. 



I now regret the omission. I thought that as Prof. Owen's name oc- 

 curred, both before and after, in connexion with the subject, and as no other 

 author was mentioned, it would easily be surmised that the suggestion was 

 his. I was moreover, as I stated before, especially anxious to avoid giving 

 a polemical appearance to my paper by too frequent citations by name, 

 where it was necessary to show a divergence of opinion. 



I now come to the alleged misrepresentation of Prof. Owen's opinions 

 contained in a foot-note to my abstract, which runs as follows : 



" In the paper by the same author [Prof. Owen] ' on the Characters, 

 Principles of Division, and Primary Groups of the Class Mammalia' (Proc. 

 Linn. Soc. 1858), the Subclass Lyencephala ('loose' or 'disconnected' 

 brain), equivalent to the Marsupialia and Monotremata, are characterized as 

 having the cerebral hemispheres but feebly and partially connected together 

 by the ' fornix ' and ' anterior commissure,' while in the rest of the class a 

 part called ' corpus callosum ' is added, which completes the connecting or 

 commissural apparatus." It is now objected that this was only intended 

 as a "zoological definition" or "character." 



Not being aware that a zoological character, valid as such, can misrepre- 

 sent an anatomical truth, when I wished to find a brief epitome of Prof. 

 Owen's latest views upon the nature of the commissures of the marsupial 

 brain, in corroboration of the one I had given in the text from his earliest 

 memoir, I adopted the above statement. I adopted it, moreover, because 

 he had himself referred to it in the following emphatic terms. I quote from 

 the well-known " Reade Lecture," delivered before the University of Cam- 



