Dury: Coleoptera of Cincinnati. 117 
COPELATUS. 
C. glyphicus Say. 
MATUS. 
M. bicarinatus Say. 
AGABUS. 
A. stagninus Say. A. teniolatus Harr. 
A. semivittatus Lec. 
I have found this last species feeding on a bit of earth worm, 
floating in water. Placing my net under the worm, and raising 1% 
up, I counted 43 of the beetles. 
DYTISCUS. 
D. fasciventris Say. D. harrisii Kby. 
D. hybridus Aube. 
ACILIUS. 
A. semisulcatus Aube. A. fraternus Harr. 
THERMONECTES. 
T. basilaris Harr. T. fasciaticollis Harr. 
CYBISTER. 
C. fimbriolatus Say. 
GYRINID-A. 
“Surface Whirligigs.” 
GYRINUS. 
G. confinis Lec. G. lugens Lec. 
G. analis Say. 
DINEUTUS. 
D. discolor Aube. D. assimilis Aube. 
HYDROPHIEIDA: 
HELOPHORUS. 
H. lineatus Say. 
HYDROPHILUS. 
H. ovatus H. & G. H. glaber Hbst. 
H. triangularis Say. H. striolatus Lec. 
H. nimbatus Say. 
Excepting Dytiseus harrisi, the first two are the largest water 
beetles found here. H. ovatus is shorter and broader and has the 
triangular piece, into which the anterior end of the sternal spine 
rests, open. H. triangularis is very common, and has the triangle 
mentioned above closed and complete. 
alr 
