WATBE-BEBTLES. 209 



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SO many of its tribe do, a not very pleasant scent. The 

 odour of some beetles, boweTer, under these circumstances is 

 by no means unpleasing. Acilius sulcaius is very adroit i;a 

 escaping from tbe aquarium if it has the slightest opportunity. 

 The larva of this beetle is not unlike that of a D. marginalis, 

 though it may be distinguished from that species by its 

 smaller size, and by its having the first segment of the body 

 so much elongated as to look like a neck. It catches its prey 

 by stealth, and, after it has seized it, sometimes shakes it as 

 a dog does a rat. This larva may be treated in the same 

 way as its larger relatives. A. fasciatus is the other species 

 which belongs to this genus. 

 It differs from A. sulcatus 

 chiefly in having yellow 

 abdomen and legs, and it 

 is not quite so large or 

 so common an insect. 



Colymbetes striatus (Fig. 

 134) is a beetle of about 

 the size of A. sulcaius, but 

 rather more oblong in 



Blianp Tt, is vprv pommon ^i°- 1**- Colymbetes stkiatus 



snape. u, is very common, (M.ii.E and Female). 



and may be fovtnd at any 



time during the year. This 



and other species of Colymhetes are strong and ready flyers, 



and are perhaps a little more likely to attack their piscine 



companions than are the members of the last genus. The 



shape of C. striatus is oblong; the elytra are brownish 



and the thorax is a yellowish brown, having a dark stripe 



in the middle; the body underneath is black and the legs 



are a duU red. This beetle while in the general aquarium 



should be watched from time to time, and if it seems likely 



to hui-t the fish, should be removed. But as a rule it may 



be taken for granted that as long as it is properly fed it 



will do no harm to its companions, at any rate dtiriag the 



greater portion of the year. C. fuscus is rather smaller in 



size and more ovate in shape than the preceding. Its elytra 



are brown, with yellowish-brown lateral margins. Its thorax 



p 



