102 Transactions. — Zoology. 



hemisphere ; bnt it is eAddent, from an examination of the drawings 

 representing the three views of a foetal Cachalot (Catodon), in the Museum of 

 the Royal College of Surgeons, that the remarkable asymmetry exists already 

 in that early state of existence. 



On tlie other hand, I may ask why should the Balcenidcn have a 

 symmetrical skull, breathing, as they do, exactly in the same manner as the 

 toothed whales 1 Eschricht, who has described the important changes which 

 the skulls of the Bcdcunidce undergo, has shown that they are in the fatal 

 state quite symmetrical, although later on slight inequalities in the maxillse 

 are sometimes discernible. 



As far as I am aware no cognizable reason can be given to account for this 

 asymmetry in the skull of the toothed whales, and we are, therefore, almost 

 led to assume that some of their remote ancestors were deformed by some 

 accident, and that thus this asymmetry of the skull was inherited by their 

 progeny to a more or less extent ; because it is difficult to believe that in the 

 struggle for existence, in the adaptation to altei-ed circumstances and a 

 different mode of life, this strange asymmetry could be of any vital 

 importance. 



The study of the ontogeny of this species, and of the phylogeny of the 

 family to which it belongs, and of its extinct ancestors is, therefore, of the 

 highest importance in considering the question of the origin of species, because 

 eveiy step in that dii-ection is a clear gain to science. 



It may be possible that this point has already been treated at length by 

 some naturalists, but I am not aware that this is the case, and my wish to 

 draw the attention of my bi-other natixralists in New Zealand and other 

 countides — where an opportunity is offi3red by acquiring specimens of toothed 

 whales in all stages of growth, to study this striking fact in osteology — has 

 been my only motive for alluding here more fully to it than I should otherwise 

 have done. 



