Fig. 1 
Fig. 2 
Fig. 3 
Fig. 4 
Fig. 5 
Fig. 6 
Fig. 7 
Fig. 8 
Fig. 9 
Fig. 10. 
Fig. 11. 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Fig. 16. 
Fig. 17. 
983 
EXPLANATION OF PLATES. 
PLATE VII. 
. Uppersurface of head of Cybister (Dytiscus reeselii, Fab.) 
. Undersurface of head of Cybister (Dytiscus reeselii, Fab.); a, inflexed angle of epicranium, 
bearing the antennal cavity ; 6, eye; c, maxillary cleft; d, gula; e, suture between proto- 
cranium and epicranium. (The artist in endeavouring to make the drawing of this figure 
look less diagramatic has diminished its anatomical value ; the curved line extending across 
the front of gula, and also the second transverse line behind the eye, indicate not sutures 
but merely depressions of the surface). 
. Anterior portion of body of Pelobius: (after Regimbart). 
. Anterior portion of body of the Dytiscide : (after Regimbart). 
. Inner face of labrum of Dytiscus (D. marginalis, L.), after Schiddte, Dan, El., Table ODI, GS 
(showing conical prominences and commencement of esophageal membrane). 
. Right mandible of Dytiscus (D. marginalis, L.), after Schisdte, Dan, El., Table OI, By I 2 
a, upper face ; 6, under face. 
. Left maxilla of Dytiscus (D. marginalis, L.), - 3 ~) e, d; 
the right hand fig. is as seen from beneath; the left hand fig. as seen from above, with 
maxillary fringe omitted ; a, leathery basal portion of inner lobe ; 6, squama ; y, stipes > 
3, hollow for palpus : (in these figs. the extremity of the inner lobe should be more abruptly 
curved). 
. Labium (outer face) of Dytiscus (D. marginalis, L.), after Schiddte Dan., IL, Waly, Oh 5% 8 
(in this fig. the supports of the labial palpi should be emarginate). 
. Labium (outer face) of Cybister (D. reeselii, Fab.) 
Labium of Dytiscus (D. marginalis, L.), after Schiddte Dan., El. XXJ, g. h. Right-hand fig., 
inner face, a, esophageal piece uniting by a curve with its fellow of opposite side ; 8, fulcrum 
or support ; y, stipes or stem ; £, paraglossa. Left-hand fig., right side of ligula, removed 
with labial palpus, and seen externally ; a, esophageal piece; P, fulcrum ; y, stipes, (this 
and the preceding seen without ciliz) ; 0, support of palpus ; «, membranous piece connecting 
y and 6; &, paraglossa. 
Antenna of Cybister (D. roeselii). 
Antenna of Hydrovatus aristidis ¢. 
Antenna of Noterus levis ¢ (after Migneaux, the joints are rather too elongate). 
Lateral aspect of undersurface of prothorax of Cybister (D. reselii); @, medisternum; 8, 
prosternal process ; c, episternum ; d, epimeron ; ¢, inflexed portion of propotum ; /, depres- 
sion for reception of front coxa. 
Lateral aspect of undersurface of prothorax of Hyphydrus (Dytiscus ovatus, L.), lettering as in 
Fig. 14. 
Middle of prosternum of Hyphydrus (Dytiscus ovatus, L.); a, medisternum ; b, prosternal process; 
c, coxal depression. 
Prosternal process of Hydrocanthus, (H. atripennis). 
