142 GEORGE H. HORN, M. D. 



tibise gradually dilated aud distinctly denticulate. Hind tibiae slender. Length 

 .05 inch ; IJ mm. 



Two specimens from Nevada, from Mr. Wm. M. Gabb. 



Our North American species of Plegaderus have certain characters 

 in common : — Thorax with more or less distinct transverse impression, 

 base not margined, lateral thickened margin not interrupted. Oblique 

 dorsal stria wanting or very indistinct. They may be distinguished 

 as follows ; 



Transverse thoracic impression visible only at the sides; 



lateral groove not attaining the basal margin Erichsonii, Lee. 



Transverse impression moderately deep, anterior and poster- 

 ior portions of disc convex. 



Elytra coarsely longitudinally strigose transversus, Say. 



Elytra punctured uniformly. 



Presternum with a single sulcus on each side; transverse 

 sulcus behind themiddle; anterior division of middle 

 convex portion elongate oval coarsely punctured. 

 Lateral sulcus of pronotum attaining basal margin, 



disc coarseiy punctured Sayi, Mars, 



Presternum with two distinct sulci on each side. 



Lateral sulcus of pronotum not attaining the basal mar- 

 gin, disc finely punctured. Base of thorax without a 

 line of coarse punctures. Anterior division of mid- 

 dle convex portion of presternum broader than long; 



transverse sulcus in front of middle nitidus, Horn. 



Lateral sulcus attaining basal margin ; the latter with 

 a row of coarser punctures. Transverse sulcus of pre- 

 sternum behind the middle and deep; anterior divi- 

 sion elongate triangular, coarsely punctured, poster- 

 ior portion very small fratemus, Horn. 



Description of Plate I. 



1. Hister Gleveri, Horn. \ 7. Hetserius californicus, Horn. 



2. Hister Arizense, Horn. 8. Hetserius brunnipennis, Rand. 



3. Hister Ulkei, Horn. 9. Hetserius setiger, Lee. 



4. Hister militaris, Horn. 10. Onthophilus, Lecontei, Horn. 



5. Margarinotus guttifer, Horn. 11. Tribalus californicus, Horn. 



6. Hetserius mersus, Lee. 12. Saprinus estriatus, Lee. 



