202 PRESH-WATEE AQTJAEIA. 



may be fed upon small garden-worms, a tiny dead fish, or 

 pieces of raw meat suspended in the water by a little hook. 

 The meat should always be removed before there is a chance 

 of its corrupting the water. 



The larvfe of these beetles, which are hatched from cylin- 

 drical eggs during the autumn and early spring, are carnivorous 

 in habit, and elongated in shape, gradually tapering towards 

 the tail. Their heads are usually provided with sickle-like 

 jaws, through which they are able to suck the juices of their 

 prey. They are very great eaters, and as they grow quickly 

 they frequently change their skuis, which are interestiag under 

 the microscope. The food of the larvae, according to their 

 size, consists of small fish, tadpoles, aquatic molluscs, insects, 

 and larvEe of insects, even occasionally of their own species. 

 When it is time for them to enter the pupal state, they leave 

 the water and make small oaves or hollows in the damp soil 

 at its edge, from which hiding-places they emerge in about a 

 fortnight, or more or less according to circumstances and 

 species, perfect beetles. Though these larvae are so rapacious 

 and fierce, they are not very tenacious of life, for a small hurt 

 will be quite sufficient to cause their death. It will be 

 frequently found, while examining the spoils of a hunt, that 

 they have been among the first to succumb. 



The Dytiscidce are divided into four sub-families, viz., 

 Dytiscides, Pelobiides, Haliplides, and Hydroporides. 



The sub-family of the Dytiscides comprises at least eight 

 genera, which are indigenous to Britain, and are : (1) Dytiscus, 

 (2) Acilius, (3) Colymbetes, (4) Ilyhius, (5) Hydaticus, (6) 

 Agabus, (7) Laccophilus, (8) Noterus. 



As there are about 220 or 230 different species of British 

 aquatic beetles, it will be quite impossible to refer in this 

 handbook to anythiag like the greater portion of them. I 

 wUl only attempt, therefore, to describe a few of the most 

 suitable for, and interesting in, the aquarium. 



In writing of the carnivorous aquatic beetles, one naturally 

 thinks first (though, perhaps, scientifically it is not quite right 

 so to do) of the handsome, bold, poptdar, and greedy Dytiscus 

 marginalis as worthy of heading the list of those which may 



