30 THE CANADIAN NATURALIST. [March 



Montreal; to this genus belongs those beetles called "Bombar- 

 diers." They have the faculty of emitting volatile discharges, 

 having a very pungent odour, accompanied with a slight noise and 

 with a bluish smoke. They are to be found plentifully at the 

 Back River under stones and decaying trees ; as many as six or 

 seven specimens may be taken under one stone. Four or five 

 discharges are the greatest number I have seen them emit ; after 

 this process the insect appears quite exhausted. 



Examples of the genus Chlaenius are also very plentiful along 

 the banks of the St. Lawrence ; at the Victoria Bridge, I have 

 secured twenty specimens under one stone, comprising three 

 species. They have a very pungent odour which remains on the 

 hands for some time after washing. 



The next three families are aquatic, viz., the Dytiscidae (or 

 diving beetles), the Gyrinidae (or whirlgigs), and the Hydrophili- 

 dae. Their food is aquatic larvae and plants ; some of the larger 

 species attack even frogs, and small fish. The foot of the male 

 Dytiscus has long been admired as a microscopic object. The 

 Gyrinidae have two pairs of eyes, which is one pair more than 

 their congeners possess ; they are largely represented in the ponds 

 and streams near the city. 



The Silphidae (or carrion beetles) may be found feeding in 

 the bodies of dead animals ; they are flat bodied insects and are 

 very useful in removing putrid carcases. 



The next family Staphylinidae (or rove beetles) contains a 

 great variety of species ; some are microscopic in their dimensions, 

 and none exceed an inch or so in length. These beetles are 

 omnivorous; some feed on decomposing animal and vegetable 

 matter, some on fungi, and others on flowers. 'I he small insects 

 which annoy us by getting into our eyes belong to this family. 



The U'lsteridae, or "mimic beetles," are the next in order, they 

 are found in excrements, in carcases, and under bark. They 

 have the power of folding their legs close to the body on being- 

 disturbed, so as to counterfeit death. 



Examples of the family Cucujidce are apparently rare on the 

 Island of Montreal. They are usually found under bark, and 

 some are of a bright scarlet colour. The two specimens I have 

 of Cucvjus davipes were captured on the board walk in St, 

 Urbain St. 



The Dermistidae, or skin beetles, are a group of insects of small 

 size, generally about three quarters of an inch long. They are very 



