IfYDRADKPHAGA. 
83 
occur when it is found iu great numbers. Unlike 
the light-loving whirlwigs, it hides itself in banks by- 
day, and mostly performs its evolutions on the water 
by dark. Its larva forms a white silky cocoon, which 
has been found under willow-bark, and in a fresh-water 
shell. 
By far the best work on the Dytiscidx is Dr. 
Sharp’s monograph above alluded to (on Aquatic 
Carnivorous Coleoptera, Trans. Royal Dublin Society, 
1880- 2). M. Regimbart’s monograph of the Gyrinidas 
(published in the French Annales for 1883) will also 
be found of the greatest service to the student of the 
group. 
