600 



A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 







b 



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d 



Figure 2. Specimen plates from Boulenger's Catalogues: a. From the Batrachia 

 gradientia, 1882, 6. From the Batracha salientia, 1882. c. From the Lizards, 1885. d. From 

 the Chelonians, 1889. These show (in modern halftone reproduction) the kind of litho- 

 graphic engraving that characterized all zoological illustration up to 1900. 



