PREFACE. 



•of the descriptions are oft the authority of the writings of 

 «Gegenbauer, Parker, and Owen, notably the latter. 



I must apologise to the reader for an accidental error in Plate I., 

 •containing skull of Dog-Fish : there are no teeth in the dry skull, 

 ;as is represented. 



At the end of the book is inserted notes on the Development 

 of the Dog-Fish, derived from the late Professor Balfour's work 

 ■on the" " Embryology of the Elasmobranchs." 



D. KNIGHT. 



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