Ti'UNEH, Morpholoo'v of (Jic Avian Bra'ni. ^cy 



approximately the ratio of the cube root of the vokimn 

 of the prosencephalon to the length of the brain. This 

 ratio is tabulated in Table II, Column \ (L X B X D). 

 In practice this ratio has proved very convenient. With one 

 exception [Ardcidic) the members of the same family differ 

 from each other by less than three per cent. 



Upon consulting Table VI, it will be seen that the group- 

 ing of the families examined agrees very well with the classi- 

 fication proposed by Prof. Huxley in 1867. Prof. Huxley's 

 classification was based upon osteological characteristics. 

 The fact that this agreement exists is to my mind an excel- 

 lent testimonial of the taxonomic value of the avian brain. 



EXPLANATION OF TABLE VII (SEE PAGE 90). 



This table has been constructed to iUustrate the vahie of the 

 •' \ (L X B X D) as a critei'ion for determining tlie rank of a family within 

 a group. The passerine group has been chosen because it has been more 

 thoroughly studied than any other group. 



In the column headed " Coues " is tabulated the order found in 

 Coues' Key to North American Birds. 



In the column headed " A. O. U." is tabulated the order found in 

 the A. O. U. Check List of North American Birds. 



In the column headed " Shufeldt '' is tabulated the order found in 

 North American Passeres, by R. W. Shufeldt, M.P., C.M.Z.S. 



In the column headed * v^(L X B X D) is tabulated the order sug- 

 gested by the ^^/(L X B X D). 



It may not be out of place to say a word or two in defense 

 of the arrangement suggested by the ■\/(L X B X D)- 



The CorvidiP are placed at the top of the list. This 

 agrees with the arrangement proposed by R. W. Shufeldt. 

 In defending his position, Mr. Shufeldt remarks: " Corvus 

 corax has a skeleton of the highest type of oscine organiza- 

 tion, a statement that applies with equal force to much else 

 in the economy; its brain is relatively larger in proportion to 

 the size of the bird than others of the same order; its young 

 substantially have the plumage of the parents at a time when, 

 as nestlings, they first take on their plumage; finally the 

 raven is a far more intelligent bird than any species of Sialia 



