336 THE CANADIAN ENTOMOLOGIST. 



These genera may be separated by the following table : 



1. (2) Anterior femora not sulcate I, Benacus, Stal. 



2. (i) Anterior femora sulcate.  



3. (10) Anterior tarsi with two claws. 



4. (9) Claws of anterior tarsi of equal length, minute. 



5. . (8) Anterior femora more or less incrassate, much larger than tibise. 



6. (7) Species with two sulci between the eyes . VII, Nectocoris, Mayr. 



7. (6) Without such sulci VIII, Sphcerodema, Lap. 



8. (5) Anterior tarsi scarcely incrassate, but little larger 



than tibicC VI, Limnogeton, Mayr. 



9. (4) Claws of anterior tarsi of equal or unequal length, 



elongate Ill, Diplonychiis, Lap. (Bueno). 



10 {3) Anterior tarsi with one claw. 



IT. (14) Head conically produced, rostrum long, thin. 



12. (13) Membrane of hemelytra large IV, Belostoma, Latr. 



13. (12) Membrane of hemelytra much reduced V, Abedus, Stal. 



14. (11) Head not conically produced, rostrum short, 



stout ; . II, Amorgius, Stal. 



A brief 'study of the three genera, Ainoj-gins, Siai ; Diplonychus, 

 Laporte (Bueno), and Belostoma, Latreille, is necessary in order to 

 elucidate my position. The difference between the adults of the three 

 genera will appear from the following comparisons : 



The Head. — In Amorgius we have the front truncate, projecting but 

 little beyond the eyes, which are in general longer than broad. Tlie vertex 

 also is not wider than one eye, and is more or less conical in shape, as is 

 Belostoma. But in Dip/onychiis the vertex is not wider than the eye, 

 while in Belostoma it is. In both the eyes are wider than long. The 

 rostrum in Amorgius is cjuite short and stout, and in Belostoma very long 

 and slender, whilst in Diplonychus it is moderately long, and as stout as 

 in the first-named genus. The prothorax is trapezoidal in all three genera, 

 but is much less narrowed anteriorly in Diplonychus than in the other two, 

 which gives it a massive aspect. The scutellum also is apparently large, 

 due to the more stout general build of this bug. The hemelytra are much 

 the same in the three except for slight variations, which are no greater 

 than those occurring in the different species of any one genus. Diplony- 

 chus agrees with Amorgius in the general outline, the sides being more or 

 less parallel, whilst in Belostoma the body is more or less pointed oval 

 posteriorly. We now come to the under side of the body and the legs. The 



