CHESTER. — STRUCTURE OF PSEUDOPLEX.\URA CRASSA. 



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EXPLANATION OF PLATES. 



Abbreviations. 



All drawings, except Figures 1 and 61, were carefully outlined with a camera 

 lucida, and the details filled in afterwards. The magnification (except in 

 Figures 1 and 61) is 675 diameters, unless otherwise indicated in the descrip- 

 tion of the Figure. 



