528 GENERAL BIOLOGY 



8. Scutellum invisible 9 



Scutellum visible 13 



9. Prosternal process broadly dilated and truncated 



behind; joints of the hind tarsi simple, without 



broadly over-lapping lobes 10 



Prosternal process compressed and pointed behind; 

 joints of the hind tarsi with broad over-lapping 

 external lobes (fig. 285.-!) (13) Laccophilus 



10. A more or less conspicuous curved spur or hook on 



the apex of the front tibia? 1 1 



No such hook present on front tibiae (S. U. S.) (i) 



N atomic r us 



1 1 . Prosternum strongly angulate in the middle ; body 



nearly globose; last joint of palpi emarginate at 

 tip ; hind coxal cavities separate ; length 3.5 mm. 



(S. U. S.) (i) Colpius 



Prosternum flat; hind coxal cavities contiguous. . 12 



12. Prosternal process very broad behind; hind tibia; 



very broad; length 4 to 7 mm.(E. U. S.) (i) 



Hydr acanthus 



Prosternal process moderately broad behind; hind 

 tibiae rather slender; length less than 4 mm. (5) 



Canthydrus 



13. Inferior spur of hind tibiae dilated, much broader than 



the other spur (5) Cybister 



The two spurs of hind tibiae of equal or nearly equal 

 breadth 14 



14. Distal margin of the segments of the hind tarsi beset 



on the outer side with a transverse row of minute 



appressed bristles (Fig. 285 fo) 27 



No such row of appressed bristles across the ends of 



the tarsal segments 15 



1 5 . Front margin of the eye circular ; the last two pairs 

 of abdominal stigmata greatly enlarged, each 



