983 



EXPLANATION OF PLATES. 



PLATE VII. 



Fig. 1. Uppersui'face of head of Cy bister (Dytiscus rceselii, Fab.) 



Fig. 2. Undersurface of head of Cybister (Dytiscus roeselii, Fab.); a, intiexed angle of epicranium, 

 bearing the antennal cavity ; h, eye ; c, maxillary cleft ; d, gula ; e, sutui'e between proto- 

 cranium and epicranium. (The artist iu 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). 



Fig. 3. Anterior portion of body of Pelobius : (after Regimbart). 



Fig. 4. Anterior jiortion of bod}' of the DytisfidiV : (after Regimbart). 



Fig. 5. Inner face of labruni of Dytiscus (D. marginalis, L.), after Schiodte, Dan, EL, Table XXI, c. ; 

 (.showing conical prominences and commencement of oesophageal membrane). 



Fig. 6. Right mandible of Dytiscus (D. marginalis, L.), after Scliiijdte, Dan, EL, Table XXI, a, b. ; 

 «, upper face ; b, under face. 



Fig. 7. Left maxilla of Dytiscus (D. marginalis, L.), ,, ,, ,, Cj d ; 



the ritjht liand 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 ; /3, squama ; y, stipes ' 

 d, hollow for paljius : (in these figs, the e.xtremity of the inner lobe should be more abniptly 

 curved). 



Fig. 8. Labium (outer face) of Dytiscus (D. marginalis, L.), after Schiodte Dan., El., Tab. XXI, f. ; 

 (in this fig. the .supports of the labial palpi should be emarginate). 



Fig. 9. Labium (outer face) of Cybister (D. rceselii, Fab.) 



Fig. 10. Labium of Dytiscus (D. marginalis, L.), after Schiodte Dan., El. XXI, g. h. Right-hand fig., 

 inner face, a, resopliageal piece uniting by a curve with its fellow of opposite side ; j3, fulcrum 

 or siijiport ; y, stijjps or .stem ; J, paraglossa. Left-hand fig., right side of ligula, removed 

 with labial pal] ms, and seen externally; a, (Esophageal piece; /3, fulcrum; y, stipes, (this 

 and the precoiling seen without cilia') ; B, support of palpus ; c, membranous piece connecting 

 y and c ; J, paraglossa. 



Fig. 11. Antenna of Cybister (D. rceselii). 



Fig. 12. Antenna of Hydrovatus aristidis $. 



Fig. 1 3. Antenna of Noterus Isevis $ (after ISIigneaux, the joints are rather too elijngate). 



Fig. 14. Lateral aspect of undersurface of pi-othor.ox of Cybister (D. roeselii) ; a, medisternum ; b, 

 prosternal process ; c, epistemum ; d, epimeron ; e. inflexed portion of pronotum ; ,/, depres- 

 sion for reception of front coxa. 



Fig. 15. Lateral aspect of undersurface of prothorax of Hyphydrus (Dytiscus ovatus, L.), lettering as in 

 Fig. 14. 



Fig. IG. ^riddle of prosteruum of Hyphydrus (Dytiscus ovatus, L.); a, medisternum ; b, prosternal process; 

 c, coxal depression. 



Fig. 17. Prosternal process of Hydrocanthus, (H. atripennis). 



