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REPTILES AND BATRACHIANS. 



shields are chiefly considered in the classification of snakes, and 

 are of great importance for the distinction of species and genera. 

 Each shield is named according to its position on the head ; as, 

 for example, the upper or lower labials or lip-shields ; rostral, or 

 beak-shields ; nasal, ocular, etc. ; and it is desirable to be 

 acquainted with these distinctions, as they characterise lizards 

 as well. 



