54 IDENTIFICATION. 



finally there is no doubt he is a Pochard. Let us compare his 

 measurements. His reference letters are Od ; the average length of 

 the species is given as i8in. ; the proportion that his wing should 

 bear to his length is '47 ; the proportion his tail should bear is '15 ; 

 the proportion his beak should bear is '12 ; the proportion his tarsus 

 should bear is '08. And now for the actual measurements : — length, 

 i75inches — we cannot quite stretch to the extraeighth — wing 8| inches; 

 tail, 2| inches ; beak, 2j inches ; tarsus, I5 inches ; which are surely 

 near enough for all practical purposes. 



A word of caution in conclusion. Do not let it be supposed that 

 the accepted classification is dependent on the mere external 

 characters we have chosen as our guides to identify. For the 

 technical descriptions of the different families, genera and species, 

 the student must go elsewhere, and he will then have his work cut 

 out for him in exploring the intricacies of synonymy, and deciding on 

 the authority he will follow in each particular case. And he will 

 probably end by being quite ready for the new classification and tlie 

 revision of the British list. 



