EXPLANATION OF PLATE I. 



FIGURE 1. Pinnixa cyliudrica Say, (p. 546 ;) male, enlarged four diameters. 

 2. Pinnotheres ostreum Say, (p. 546 ;) male, enlarged four diameters. 

 3. Panopeus depressus Smith, (p. 547 ;) male, natural size. 

 4. Platyonichus ocellatus Latreille, (p. 547 ;) male, slightly reduced in size. 



(All the figures were drawn by J. H. Eraerton.) 



