THE PREDACEOITS DIVING IJKKTKKS. 221 



Lake, Laporte and Starke counties; scarce. May 28-August 20. 



H. tencbntsus Lee., is known from New Jersey and Lake Su- 

 perior. 



Tribe II. COLYMBETINI. 



This tribe includes diving beetles of medium size or above, hav- 

 ing the tai'si distinctly 5-jointed, those of the males with the dilated 

 joints oblong. Nine genera are known to be represented in the 

 State, while a single species of another may occur. 



KEY TO INDIANA GENERA OF COLYMBETINI. 



(i. Semimembranous side pieces of first dorsal segment smooth; smaller, 



rarely 11 mm. 

 1>. Hind tarsi with unequal claws. 



c. Spine of prosteruum not snlcate; elytra with a pale pubescent spot 

 on the inner face at apex. X. II.YBIUS. 



cc. Spine of prosternum deeply sulcate ; elytra without pale spot. 



XI. MATUS. 

 bh. Hind tarsi with claws equal or nearly so. 



(1. Last joint of palpi emarginate; prosternal process much swollen 

 along the middle. XII. COPTOTOMUS. 



(Id. Last joint of palpi normal, not dilated or emarginate. 



c. Elytra deeply striate; prosternal spine but little swollen at mid- 

 dle. XIII. COPEI.ATUS. 

 ee. Elytra not distinctly striate. 



/. Thorax not margined ; elytra beneath the lens showing numer- 

 ous very fine elongate stria?; prosternum not sulcate. 



XIV. AGABETKS. 

 if. Thorax margined at sides. 



<l. Elytra with very fine longitudinal impressions; hind legs 



short and stout; wing of metasternum linear, strongly 



curved. XV. ILYBIOSOMA. 



ffff. Elytra without fine stripe; hind legs of medium length and 



size ; wing of metasternum wedge-shaped. XVI. AGABUS. 



(Hi. Semimembrauous side pieces of first dorsal segment rugose; larger. 



usually 12 or more mm. 

 //. Upper surface conspicuously reticulate; thorax not margined on sides. 



SCUTOPTERI'S. 



lilt. Upper surface not reticulate. 



/. Elytra smooth, or in the female with short coarse lines; metas- 

 ternum with a broad, deep groove; thorax margined. 



XVII. RHANTI s. 



/'/. Elytra with fine transverse wrinkles: metasternum with a narrow 

 indistinct groove : thorax not margined. XVIIT. < 'or.viui:i-:TKs. 



The ru.u'osil ics referred to under <ui in Hie above lable are near 

 111;- Mrs! spiracle,' and the '-Ivtron must be raised to see Ilieni prop 

 erly. 



